fix(android): restore image picker after Activity recreation (#7546)

Backport expo/expo#49634 to SDK 54 so retained launchers register
against the current Activity after their previous owner is destroyed.
Cover repeated recreation and replacement-before-destroy ordering with
native regression tests, and document the native rebuild requirement.

Co-authored-by: luke <luopeihuan@gmail.com>
Co-authored-by: Ido Yana <idoyana@gmail.com>
Co-authored-by: RoundRedDot <roundreddot@gmail.com>
Co-authored-by: paseo-bot[bot] <266920839+paseo-bot[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -3,8 +3,8 @@ name: CI
 on:
   push:
     branches: [main]
+  # Every base branch, so stacked PRs and PRs into `next` get the same checks.
   pull_request:
-    branches: [main]
   merge_group:
   workflow_dispatch:
 
@@ -417,6 +417,14 @@ jobs:
       - name: Run app unit tests
         run: npm run test --workspace=@getpaseo/app
 
+      - uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: "21"
+
+      - name: Run Android module tests
+        run: npm run test:android --workspace=@getpaseo/app
+
   playwright-1:
     name: playwright (shard 1/8)
     needs: changes

.github/workflows/desktop-packages.yml

@@ -6,7 +6,6 @@ on:
   # Packaging leaves ordinary PR CI, but a PR that changes what gets packaged
   # or how it is smoked still proves the real artifacts before merge.
   pull_request:
-    branches: [main]
     paths:
       - "packages/desktop/**"
       - "plugins/**"

CLAUDE.md

@@ -41,6 +41,7 @@ At the start of non-trivial work, list `docs/` and skim anything relevant to the
 | [docs/forge-providers.md](docs/forge-providers.md)                   | Adding a git forge: registry/manifest, drop-in checklist, self-host/GHES, the two facts tiers                                  |
 | [docs/custom-providers.md](docs/custom-providers.md)                 | Custom provider config: Z.AI, Alibaba/Qwen, ACP agents, profiles, custom binaries                                              |
 | [docs/plugins.md](docs/plugins.md)                                   | Local plugin manifest, directory source config, RPCs, native surfaces, and attachment sources                                  |
+| [docs/website-i18n.md](docs/website-i18n.md)                         | Website languages: locale URLs, translated Markdown pairs, `{#id}` anchors, Chinese style                                      |
 | [docs/service-proxy.md](docs/service-proxy.md)                       | Service proxy: exposing workspace scripts at public URLs, DNS setup, reverse proxy config                                      |
 | [docs/development.md](docs/development.md)                           | Dev server, build sync gotchas, CLI reference, agent state, Playwright MCP                                                     |
 | [docs/rpc-namespacing.md](docs/rpc-namespacing.md)                   | WebSocket RPC naming convention — dotted namespaces and `.request`/`.response` pairs                                           |
@@ -106,6 +107,8 @@ npm run format:check                 # Check formatting without writing
 
 Repo dev commands use checkout-local state by default. In this checkout, `PASEO_HOME` resolves to `.dev/paseo-home`, and `npm run cli -- ...` targets that same dev home automatically. The packaged desktop app and production-style daemon keep using `~/.paseo` on port `6767`.
 
+When Mo requests an APK, use `npm run build:apk:arm64` for an ARM64 build: writes `artifacts/paseo-dogfood-arm64.apk` with diagnostics without starting a device; `npm run build:apk` builds all four Android architectures.
+
 See [docs/development.md](docs/development.md) for full setup, build sync requirements, and debugging.
 
 ## Release branches

README.zh-CN.md

@@ -59,8 +59,8 @@
 <table>
   <tr>
     <td align="center" width="33%"><a href="https://hoplite.sh/?utm_source=paseo&utm_medium=readme&utm_campaign=sponsor"><picture><source media="(prefers-color-scheme: dark)" srcset="packages/website/public/sponsors/hoplite-on-dark.svg"><img src="packages/website/public/sponsors/hoplite-on-light.svg" alt="Hoplite" height="40"></picture></a><br><sub>Cloud coding agents</sub></td>
-    <td align="center" width="33%"><a href="https://paseo.sh/sponsor">成为 Paseo 赞助商</a></td>
-    <td align="center" width="33%"><a href="https://paseo.sh/sponsor">成为 Paseo 赞助商</a></td>
+    <td align="center" width="33%"><a href="https://paseo.sh/zh-CN/sponsor">成为 Paseo 赞助商</a></td>
+    <td align="center" width="33%"><a href="https://paseo.sh/zh-CN/sponsor">成为 Paseo 赞助商</a></td>
   </tr>
 </table>
 
@@ -80,7 +80,7 @@ Paseo 会运行一个名为 daemon 的本地服务，用来管理你的 coding a
 
 ### 桌面 app（推荐）
 
-从 [paseo.sh/download](https://paseo.sh/download) 或 [GitHub releases 页面](https://github.com/getpaseo/paseo/releases)下载。打开 app 后 daemon 会自动启动，不需要再安装其他东西。
+从 [paseo.sh/download](https://paseo.sh/zh-CN/download) 或 [GitHub releases 页面](https://github.com/getpaseo/paseo/releases)下载。打开 app 后 daemon 会自动启动，不需要再安装其他东西。
 
 如果要从手机连接，在 Settings 中扫描显示的二维码。
 
@@ -97,8 +97,8 @@ paseo
 
 完整安装和配置见：
 
-- [文档](https://paseo.sh/docs)
-- [配置参考](https://paseo.sh/docs/configuration)
+- [文档](https://paseo.sh/zh-CN/docs)
+- [配置参考](https://paseo.sh/zh-CN/docs/configuration)
 
 ## CLI
 
@@ -116,7 +116,7 @@ paseo send abc123 "also add tests" # 发送后续任务
 paseo --host workstation.local:6767 run "run the full test suite"
 ```
 
-更多内容见[完整 CLI 参考](https://paseo.sh/docs/cli)。
+更多内容见[完整 CLI 参考](https://paseo.sh/zh-CN/docs/cli)。
 
 ## Skills
 
@@ -164,7 +164,7 @@ npm run typecheck
 
 ## 支持 Paseo
 
-Paseo 由一个人开发，靠使用它的人来资助。你可以通过 [GitHub Sponsors](https://github.com/sponsors/boudra) 支持这项工作。公司也可以按月[赞助 Paseo](https://paseo.sh/sponsor#spot)，logo 会展示在本 README 顶部，以及 paseo.sh 的首页和文档中。
+Paseo 由一个人开发，靠使用它的人来资助。你可以通过 [GitHub Sponsors](https://github.com/sponsors/boudra) 支持这项工作。公司也可以按月[赞助 Paseo](https://paseo.sh/zh-CN/sponsor#spot)，logo 会展示在本 README 顶部，以及 paseo.sh 的首页和文档中。
 
 ## 相关项目
 

docs/agent-lifecycle.md

@@ -71,6 +71,8 @@ normal root agent immediately, and closing its still-open tab archives it.
 
 Runtime ownership is resolved from explicit workspace ID and caller context, never from `cwd`. Workspace creation is a separate operation with `local | worktree` isolation; agent creation reuses that workspace unless a new workspace is explicitly requested.
 
+Setup belongs to the workspace, including combined workspace-plus-agent creation and the supported agent `worktree` request. Run setup through the workspace workflow before launching configured terminals or scripts. Setup output is read in the Setup panel from per-command snapshots; never produce setup chat timeline rows or concatenate command logs. Legacy agent `git`/`worktreeName` inputs and hidden MCP worktree placement are rejected with workspace-creation guidance. Existing wire schemas retain an empty combined-log string for parsing compatibility.
+
 Users can also detach an existing subagent from the subagents track. Detach is deliberately a manual lifecycle gesture, not an agent-facing MCP tool. It removes the parent and open-tab lifecycle labels: it does not stop, archive, move, or restart the agent. The agent keeps its current `cwd` and `workspaceId`, leaves the former parent's track, and behaves like a root agent for tab close, workspace activity, and future parent archive.
 
 `notifyOnFinish` defaults to `true` for agent-scoped creation and prompt follow-ups because most delegated work needs to report back to the creating agent. Set it to `false` only for truly fire-and-forget agents or prompts.

docs/android.md

@@ -61,39 +61,81 @@ Gradle auto-fetches the platform/build-tools it needs once licenses are accepted
 
 ## Local build + install
 
+The locked `expo-modules-core@57.0.23` needs the patch installed by `npm install`.
+It backports
+[Expo's Activity-result launcher fix](https://github.com/expo/expo/pull/49634): changing
+font size or another unhandled configuration can otherwise disable image selection
+until the app process restarts. Rebuild the native app after changing this patch;
+a Metro reload cannot update it. Remove the patch when the installed
+`expo-modules-core` includes the fix.
+
+Run its native regression tests from `packages/app/android` after prebuild:
+
+```bash
+./gradlew :expo-modules-core:testDebugUnitTest \
+  --tests expo.modules.kotlin.activityresult.AppContextActivityResultRegistryRecreationTest \
+  --no-daemon --max-workers=1 -Dorg.gradle.parallel=false
+```
+
 From repo root:
 
 ```bash
-npm run android:development    # Debug build
-npm run android:production     # Release build
-npm run android:clear          # Remove generated Android project
+npm run build:apk       # Universal dogfood APK: 32/64-bit ARM and x86
+npm run build:apk:arm64 # Smaller dogfood APK for ARM64 phones
+npm run dev:android     # Build/install the debug app and start development
+npm run dev:ios         # Build/install the iOS development app
 ```
 
-For a production-ID release APK that local Android profiling tools can attach to:
+`build:apk` writes `artifacts/paseo-dogfood-universal.apk`; `build:apk:arm64` writes
+`artifacts/paseo-dogfood-arm64.apk`. Neither command launches or installs on a device. Both enable
+`PASEO_WATCHDOG_BUILD=1`, the production React profiling renderer, and Android's shell-profileable
+flag. These builds keep the production package ID (`sh.paseo`) and release optimizations. Use this APK for
+personal dogfooding. Android system-trace spans require the separate `PASEO_PROFILE_BUILD=1` flag;
+watchdog recording does not send duplicate spans to that sink by default. Normal store/release
+workflows leave diagnostics disabled.
+
+The older `android`, `android:development`, and `ios` commands remain aliases for development.
+`android:production` still builds and installs a release through Expo; use `build:apk` when you
+need an artifact. `android:clear` removes the generated Android project.
+
+Run `npm run test:android --workspace=@getpaseo/app` to prebuild Android and run native module unit tests. The app CI job runs this command with the Android toolchain.
+
+### Diagnostic logs without ADB
+
+In a dogfood build, open Android's Files app → Downloads → **Paseo diagnostics** and share all
+retained `.jsonl` files. No app screen, storage permission, or attached debugger is required.
+The recorder retains eight files of about 5 MiB each across reconnects and app restarts. Rotation
+replaces the oldest files, so collect them soon after reproducing a freeze. Uninstall/reinstall
+can leave older Downloads files that the new installation cannot manage.
+
+Each file identifies its build and session. Events include application-transport frame sizes and
+message/request IDs, connection transitions, parse/validation/dispatch spans, named React subtree
+render timings, and foreground JS heartbeat gaps. Payloads, passwords, and message contents
+are excluded; connection identifiers include host addresses. Each size has a unit: **bytes** when
+already available, otherwise **UTF-16 code units** for text. These are
+client transport observations, after relay decryption where applicable, not packet arrival times.
+
+The native recorder flags a heartbeat overdue by more than 500 ms (250 ms expected interval).
+A heartbeat gap bounds the unresponsive interval; it is not an exact blocked-stack duration.
+Backgrounding suspends detection. `js.stall.started` can be written while JS remains blocked;
+`js.stall.recovered` records the gap when JS resumes. Recovery can appear without a start event
+when JS resumes before the next native sampling tick. Process death leaves earlier files intact,
+but queued/unflushed records can be lost. A missing recovery event alone does not prove a crash.
+
+`react.render.slow` records subtree rendering taking at least 16 ms; one-second summaries include
+faster renders. Nested profiler timings overlap: don't add parent and child times. React's render
+measurements do not measure native layout/paint or the complete commit phase. `recorder.dropped`
+means the bounded queue overflowed; missing events in that interval must not be treated as absence
+of activity. Storage failure stops recording rather than blocking the app.
+
+For an ordinary release APK with system trace markers only:
 
 ```bash
 PASEO_PROFILE_BUILD=1 npm run android:production
 ```
 
-This keeps the `sh.paseo` package id, release Hermes bundle, and release optimizations. It adds
-`<profileable android:shell="true" />` and enables local Android trace markers for workspace mounts
-and daemon WebSocket traffic. The markers contain message types and sizes, never payload contents,
-and emit only while a system trace records the `sh.paseo` app (`perfetto -a sh.paseo ...`).
-
-Or from `packages/app`:
-
-```bash
-# Debug
-npx cross-env APP_VARIANT=development expo prebuild --platform android --clean --non-interactive
-npx cross-env APP_VARIANT=development expo run:android --variant=debug
-
-# Release
-npx cross-env APP_VARIANT=production expo prebuild --platform android --clean --non-interactive
-npx cross-env APP_VARIANT=production expo run:android --variant=release
-
-# Clear generated Android project
-rm -rf android
-```
+Those markers emit only while a system trace records `sh.paseo` (`perfetto -a sh.paseo ...`);
+they do not produce Downloads files.
 
 ## Running on an emulator against a worktree daemon
 

docs/i18n.md

@@ -1,6 +1,6 @@
 # I18n
 
-Paseo client UI translations live in `packages/app/src/i18n`.
+Paseo client UI translations live in `packages/app/src/i18n`. Website translations are in [website-i18n.md](website-i18n.md).
 
 ## Supported Locales
 

docs/plugins.md

@@ -86,6 +86,12 @@ plugin before compiling and starting from disk. A failed reload stays failed; Pa
 the old code. Use `enable`, `disable`, and `remove` to manage one plugin. Removing a directory source
 never deletes it. The global `pluginsEnabled` switch remains available.
 
+## Client translations
+
+Plugin runtime translations follow the connected app, so never send a daemon locale through RPCs or add plugin resources to the app catalog. The installation owns the translation engine; native portal bridges must carry it alongside RPC and client-state contexts. Keep host label resolution at presentation time so language changes preserve the installation lifetime.
+
+The author contract is in [runtime translations](../public-docs/plugins/reference.md#runtime-translations).
+
 ## Built-in plugins
 
 Built-in plugins ship from `plugins/<id>/`, with `paseo-plugin.json`, `index.server.ts`,
@@ -240,7 +246,7 @@ Do not put any other code modules in the plugin root.
 
 Shared files import contract helpers and types from `@getpaseo/plugin`. Server handler files import
 `PluginHandlerContext` from `@getpaseo/plugin/server`. Client files import Paseo UI from
-`@getpaseo/plugin/client/react-native`. Its `Icon` draws a Lucide name from the client's installed
+`@getpaseo/plugin/client/ui`. Its `Icon` draws a Lucide name from the client's installed
 icon set, or any `PluginIcon` through its `icon` prop; an unknown name or unsafe SVG renders nothing
 so it cannot break the plugin surface.
 Its controlled modal keeps presentation metadata on `<Modal title="…" icon={…}>` and body UI in
@@ -257,14 +263,14 @@ Classify every SDK export before adding it. All client entry points and implemen
 Zod schemas, and functions that run in both runtimes. A type-only import is still an architectural
 dependency; shared types must not refer to React components, hooks, Node APIs, or server contexts.
 
-| Entry                                                | Owns                                                                       | May depend on          |
-| ---------------------------------------------------- | -------------------------------------------------------------------------- | ---------------------- |
-| `@getpaseo/plugin`                                   | Shared data, schemas, RPC/settings definitions, runtime-neutral helpers    | Shared code only       |
-| `@getpaseo/plugin/server`                            | Server contexts, lifecycle contracts, and CLI process launch               | Shared and server code |
-| `@getpaseo/plugin/server/provider`, `/server/acp`    | Server provider contracts and adapters                                     | Shared and server code |
-| `@getpaseo/plugin/client`                            | Client contribution contexts, hooks, navigation, and UI contribution types | Shared and client code |
-| `@getpaseo/plugin/client/react-native`, `/client/ui` | Host-provided UI components                                                | Shared and client code |
-| `@getpaseo/plugin/client/host`                       | App-owned rendering integration; not a plugin-author entry                 | Shared and client code |
+| Entry                                             | Owns                                                                       | May depend on          |
+| ------------------------------------------------- | -------------------------------------------------------------------------- | ---------------------- |
+| `@getpaseo/plugin`                                | Shared data, schemas, RPC/settings definitions, runtime-neutral helpers    | Shared code only       |
+| `@getpaseo/plugin/server`                         | Server contexts, lifecycle contracts, and CLI process launch               | Shared and server code |
+| `@getpaseo/plugin/server/provider`, `/server/acp` | Server provider contracts and adapters                                     | Shared and server code |
+| `@getpaseo/plugin/client`                         | Client contribution contexts, hooks, navigation, and UI contribution types | Shared and client code |
+| `@getpaseo/plugin/client/ui`                      | Host-provided UI components                                                | Shared and client code |
+| `@getpaseo/plugin/client/host`                    | App-owned rendering integration; not a plugin-author entry                 | Shared and client code |
 
 Server code imports shared helpers from the root and server capabilities from `/server`. Client
 code imports shared helpers from the root and client capabilities from `/client`. Neither runtime
@@ -556,6 +562,24 @@ one section's order from built-ins, plugin groups, and the section's preference
   remembers under its own key. It shares header ids and the `plugin:<pluginId>:<id>` settings key
   with new-API items.
 
+## Contribute file panels
+
+Client `addFilePanel` registrations become the body of a file tab. The tab stats the file, picks a
+panel, and mounts it with a `PluginFile` handle; the panel reads, shows its own `Loading`, writes,
+and resolves conflicts. The bar only switches panels and shows the dot the panel sets through
+`tab.setModified`. Built-in panels (Markdown, HTML, Image, and Source, Paseo's editor) take the
+same handle as plugin panels, so a fix to reading, watching, or writing lands in one place:
+`packages/app/src/file-panels/file/`. Do not add a host-side read or loading gate for one panel;
+make that panel faster instead. Source highlights a large file on native in idle-time slices,
+the lines around the opening line first.
+
+The handle checks every write against the version it last read or wrote, so two panels or a panel
+and an agent cannot silently overwrite each other. The daemon reports the file's kind (text,
+image, binary) with its stat from a bounded sniff, which is how Source claims text files without a
+read. See the [public file panel reference](../public-docs/plugins/reference.md#file-panels) for
+the author API, selection, `DocumentFrame`, and the version requirement. The examples live in
+`plugin-examples/pdf-panel` and `plugin-examples/markdown-panel`.
+
 ## Contribute buttons
 
 Header buttons and composer pills share the client-only descriptor and registration lifecycle in

docs/release.md

@@ -62,9 +62,10 @@ release. This applies to both beta and stable releases.
   the changelog. Retarget remaining PRs based on `next` to `main` and delete the integrated
   `next`. Create it fresh when needed again.
 
-**Setup still needed:** CI, Docker, and Nix PR checks currently target only `main`,
-and GitHub permits only squash merges. Enable checks and required-check protection
-for `next`, CI on its pushes, and merge commits for the integration PR. Handle PR
+**Setup still needed:** PR checks run for every base branch, but CI, Docker, and Nix
+push runs target only `main`, and GitHub permits only squash merges. Enable
+required-check protection for `next`, CI on its pushes, and merge commits for the
+integration PR. Handle PR
 base changes (`edited` events) so retargeting runs checks against the new base;
 GitHub's default PR events do not cover this. Deployment triggers stay unchanged.
 
@@ -533,6 +534,14 @@ No prefix (`v`), no extra text. `Release Notes Sync` matches the `## X.Y.Z` (or
 
 Older prerelease bodies on GitHub keep the notes they were synced with; `Release Notes Sync` only writes the release whose tag matches the top entry.
 
+## Changelog translations
+
+`CHANGELOG.zh-CN.md` holds the Chinese notes for `paseo.sh/zh-CN/changelog`. Only the website reads it; the app's **What's new** sheet, GitHub release bodies and F-Droid read `CHANGELOG.md`.
+
+- Translations never gate a release. Translate a new entry in a follow-up PR, or in the changelog commit when you can.
+- A translated entry uses the English heading unchanged: `## X.Y.Z - YYYY-MM-DD`. The website uses it only while the version and date both match the English entry. Otherwise it shows that release whole in English under a notice, so a beta rewritten in place drops its old translation until the new notes are translated. Delete Chinese entries whose English entry was renamed.
+- Keep the English sections, bullets and links one to one. Section titles: Added 新增, Improved 改进, Changed 变更, Fixed 修复, Security 安全, Breaking 破坏性变更, Plugins 插件, Notes 说明. Wording follows [website-i18n.md](website-i18n.md#chinese-style).
+
 ## Changelog ownership
 
 - **The agent running the release writes the changelog entry — beta or stable.** The release context and final wording stay with that agent.

docs/website-i18n.md

@@ -0,0 +1,51 @@
+# Website translations
+
+paseo.sh is served in English and Simplified Chinese (`zh-CN`). This doc covers the website in `packages/website`. App UI translations are in [i18n.md](i18n.md).
+
+## URLs own the language
+
+- English pages keep their unprefixed paths. Every other language lives under its tag: `/docs/cli` and `/zh-CN/docs/cli` are the same page. `/en/...` is not a page.
+- The server renders the language in the URL. There is no browser-language detection or redirect, so a shared link always opens in the language it was shared in.
+- The language selector moves to the same page in the other language and keeps the query and hash. Every internal link on a page carries the page's language, so the choice sticks while the reader navigates. An explicit English URL always renders English.
+- The choice is not stored. A stored choice could only take effect by redirecting unprefixed URLs, which are the English pages. First-party links into the site carry the reader's language instead: `README.zh-CN.md` links to `/zh-CN/...`.
+- Routes live under `src/routes/{-$locale}/`. Build internal links with `localizePath` or `useLocalizePath` from `~/i18n`. Links inside Markdown are localized by `DocsMarkdown`. Files, `.md` sources, `llms.txt` and API endpoints keep one path for every language (`isPagePath`).
+- Give each page's `head` the language-neutral path through `pageMeta` (`src/meta.ts`). It writes the self canonical, the `hreflang` alternates with English as `x-default`, and `og:locale`. The sitemap in `vite.config.ts` lists the same alternates.
+
+## Where copy lives
+
+| Content          | English                                            | Chinese                                                                         |
+| ---------------- | -------------------------------------------------- | ------------------------------------------------------------------------------- |
+| Interface copy   | `src/i18n/resources/en.json`                       | `src/i18n/resources/zh-CN.json`                                                 |
+| Docs             | `public-docs/<page>.md`                            | `public-docs/<page>.zh-CN.md`                                                   |
+| Blog posts       | `posts/<slug>.md`                                  | `posts/<slug>.zh-CN.md`                                                         |
+| Comparison pages | `src/content/alternatives/<slug>.md`               | `src/content/alternatives/<slug>.zh-CN.md`                                      |
+| Legal pages      | `legal/<page>.md`                                  | `legal/<page>.zh-CN.md`                                                         |
+| Changelog        | `CHANGELOG.md`                                     | `CHANGELOG.zh-CN.md`, see [release.md](release.md#changelog-translations)       |
+| Plugin listings  | the plugin's `paseo-plugin.json` and `OVERVIEW.md` | `translations` and `OVERVIEW.zh-CN.md`, see `public-docs/plugins/publishing.md` |
+
+`en.json` types the keys, so typecheck fails when `zh-CN.json` misses one. A translation file is grouped with its English original by name (`src/markdown-content.ts`). A translation without an English original fails the build.
+
+Every first-party page has a translation. The changelog and plugin listings are the exceptions: a release or listing without one renders whole in English under a notice. Pages never mix languages paragraph by paragraph. Navigation order, categories and slugs always come from the English file's frontmatter.
+
+## Editing a translated doc
+
+Edit the English file and its `.zh-CN.md` in the same PR, and add the `.zh-CN.md` with any new page. Code blocks, commands, flags, config keys and links are copied verbatim, so code-only changes are a copy. Never delete a translation to get around an edit, and never leave one that describes behavior the English no longer has.
+
+Translated headings pin the English anchor with a trailing `{#id}`, so `/zh-CN/docs/cli#running-agents` lands on the same section as the English link:
+
+```md
+## 运行 Agent {#running-agents}
+
+:::example[回复 Slack 提及 {#answer-a-slack-mention}]
+```
+
+When you rename an English heading, change the `{#id}` in the translation to the new slug. `src/content-translations.test.ts` fails when a docs, blog, comparison or legal page has no translation, and when a translation's headings differ from the English in count, level, order or anchor. It cannot tell whether the prose under a heading is current. The `.md` source endpoints serve files verbatim, so `{#id}` shows there as written.
+
+## Chinese style
+
+- Keep code, commands, file paths, IDs, brand and product names, and command output in English.
+- Keep these terms in English: Agent, worktree, daemon, Provider, PR, diff, Composer, Hub, workflow, heartbeat, slug.
+- Translate these: workspace 工作区, host 主机, relay 中继, plugin 插件, skill 技能, review 审查, schedule 定时任务, orchestration 编排, configuration 配置, prompt 提示词, subagent 子 Agent.
+- Quote app UI labels with the app's Chinese wording from `packages/app/src/i18n/resources/zh-CN.ts`, such as **设置 → 插件**. Labels the app has not translated stay in English, as do labels in Hub, GitHub, Slack and Discord. Add the English label in parentheses only where readers search for it, such as an error message.
+- Put a space between Chinese and Latin text or numbers: `启动 Agent`, `共 3 个`.
+- Bold that ends in full-width punctuation does not render when Chinese text follows it directly: `**注意：**这里` shows the asterisks. Move the punctuation outside the bold (`**注意**：这里`).

nix/npm-deps.hash

@@ -1 +1 @@
-sha256-7B/Zyo/DaHdd3PVq8Hn1HG+x+wLdZBVxgx/cbtaM/S8=
+sha256-Et1ofRqkqFoGETnbeqXuy2RerFT0kkk5F+VwDXak+fk=

package-lock.json

@@ -42116,6 +42116,7 @@
       "version": "0.12.0",
       "dependencies": {
         "@agentclientprotocol/sdk": "^1.4.0",
+        "i18next": "^26.3.0",
         "use-sync-external-store": "^1.6.0"
       },
       "devDependencies": {
@@ -43338,9 +43339,11 @@
         "@tanstack/react-start": "^1.168.26",
         "framer-motion": "^12.35.2",
         "github-slugger": "^2.0.0",
+        "i18next": "^26.3.0",
         "lucide-react": "^1.7.0",
         "react": "^19.1.4",
         "react-dom": "^19.1.4",
+        "react-i18next": "^17.0.8",
         "react-markdown": "^10.1.0",
         "rehype-autolink-headings": "^7.1.0",
         "rehype-pretty-code": "^0.14.3",

package.json

@@ -41,12 +41,16 @@
     "dev:server:watch": "concurrently --kill-others --names protocol,client,server --prefix-colors yellow,blue,cyan \"npm run watch:protocol\" \"npm run watch:client\" \"npm run dev:server:raw\"",
     "dev:server:raw": "npm run dev --workspace=@getpaseo/server",
     "dev:app": "cross-env PASEO_LISTEN=127.0.0.1:6768 EXPO_PORT=8081 ./scripts/dev-app.sh",
+    "dev:android": "npm run dev:android --workspace=@getpaseo/app",
+    "dev:ios": "npm run dev:ios --workspace=@getpaseo/app",
     "test:e2e:mobile": "./scripts/test-mobile-agent-device.sh",
     "test:e2e:composer-keyboard:android": "./packages/app/e2e/mobile/composer-keyboard/android.sh",
     "dev:website": "npm run dev --workspace=@getpaseo/website",
     "postinstall": "node scripts/postinstall-patches.mjs",
     "prepare": "lefthook install --force",
     "build": "npm run build --workspaces --if-present",
+    "build:apk": "node scripts/build-apk.mjs",
+    "build:apk:arm64": "node scripts/build-apk.mjs arm64",
     "build:highlight": "npm run build --workspace=@getpaseo/highlight",
     "build:highlight:clean": "npm run build:clean --workspace=@getpaseo/highlight",
     "build:plugin": "npm run build --workspace=@getpaseo/plugin",
@@ -80,15 +84,14 @@
     "acp:version-drift:check": "node scripts/check-acp-catalog-version-drift.mjs --fail-on-drift",
     "acp:version-drift:update": "node scripts/check-acp-catalog-version-drift.mjs --update",
     "start": "npm run start --workspace=@getpaseo/server",
-    "android": "npm run android --workspace=@getpaseo/app",
+    "android": "npm run dev:android",
     "android:development": "npm run android:development --workspace=@getpaseo/app",
     "android:production": "npm run android:production --workspace=@getpaseo/app",
     "android:release": "npm run android:production --workspace=@getpaseo/app",
     "android:clear": "npm run android:clear --workspace=@getpaseo/app",
-    "android:clean": "npm run android:clean --workspace=@getpaseo/app",
     "fdroid:changelogs": "node scripts/sync-fdroid-changelogs.mjs",
     "fdroid:changelogs:check": "node scripts/sync-fdroid-changelogs.mjs --check",
-    "ios": "npm run ios --workspace=@getpaseo/app",
+    "ios": "npm run dev:ios",
     "web": "npm run web --workspace=@getpaseo/app",
     "dev:desktop": "cross-env PASEO_LISTEN=127.0.0.1:6768 npm run dev --workspace=@getpaseo/desktop",
     "dev:win:desktop": "npm run dev:win --workspace=@getpaseo/desktop",

packages/app/app.config.js

@@ -10,6 +10,7 @@ const withAndroidScroll = require("./modules/paseo-scroll/app.plugin");
 const { getNativeReleaseVersion } = require("./native-release-version");
 const appVariant = process.env.APP_VARIANT ?? "production";
 const isFdroidBuild = process.env.PASEO_FDROID_BUILD === "1";
+const isWatchdogBuild = process.env.PASEO_WATCHDOG_BUILD === "1";
 const isProfileBuild = process.env.PASEO_PROFILE_BUILD === "1";
 
 const buildProfile = isFdroidBuild
@@ -181,7 +182,7 @@ export default {
         },
       ],
       ...buildProfile.fdroidPlugins,
-      ...(isProfileBuild ? [withAndroidProfileable] : []),
+      ...(isProfileBuild || isWatchdogBuild ? [withAndroidProfileable] : []),
     ],
     experiments: {
       typedRoutes: true,
@@ -191,6 +192,9 @@ export default {
     extra: {
       fdroidBuild: isFdroidBuild,
       profileBuild: isProfileBuild,
+      watchdogBuild: isWatchdogBuild,
+      diagnosticRevision: process.env.PASEO_DIAGNOSTIC_REVISION,
+      diagnosticBuildTime: process.env.PASEO_DIAGNOSTIC_BUILD_TIME,
       router: {},
       eas: {
         projectId: "0e7f65ce-0367-46c8-a238-2b65963d235a",

packages/app/e2e/browser/changes-pane.spec.ts

@@ -832,6 +832,9 @@ test("compact Changes keeps its actions compact and menu-only", async ({ page })
   await useUnwrappedDiffLines(page);
   await openWorkspaceChanges(page, workspace);
   await page.setViewportSize({ width: 480, height: 900 });
+  // The shell survives the breakpoint, so the wide Explorer can still be on screen right after the
+  // resize. Check for the compact tab only once the shell reports the compact layout.
+  await expect(page.getByTestId("compact-shell")).toBeVisible();
 
   const compactChangesTab = page
     .getByTestId("workspace-tab-changes_tree")
@@ -1844,9 +1847,14 @@ async function changeCodeTypographyFromSettings(
   await page.getByTestId("sidebar-settings").click();
   await expect(page).toHaveURL(new RegExp(`${buildSettingsSectionRoute("general")}|/settings$`));
   await page.getByRole("button", { name: "Appearance" }).click();
+  // A committed font change remounts the screen (AppearanceStyleBoundary), and the new form starts
+  // from the stored size. Edit the size only in the remounted form, or the remount drops it.
+  const sizeField = page.getByLabel("Code font size");
+  await sizeField.evaluate((field) => field.setAttribute("data-e2e-before-font-family", ""));
   await page.getByLabel("Code font family").fill(typography.fontFamily);
   await page.getByLabel("Code font family").press("Enter");
-  await page.getByLabel("Code font size").fill(String(typography.fontSize));
+  await expect(page.locator("[data-e2e-before-font-family]")).toHaveCount(0);
+  await sizeField.fill(String(typography.fontSize));
   await page.getByLabel("Code font size").press("Enter");
   await expect(page.getByLabel("Code font family")).toHaveValue(typography.fontFamily);
   await expect(page.getByLabel("Code font size")).toHaveValue(String(typography.fontSize));

packages/app/e2e/browser/file-change-conflicts.spec.ts

@@ -56,45 +56,12 @@ async function replaceEditorText(page: Page, content: string): Promise<void> {
   await editor.type(content);
 }
 
-async function replaceFileAfterDeletionWasObserved(input: {
-  page: Page;
-  gate: Awaited<ReturnType<typeof installDaemonWebSocketGate>>;
-  filePath: string;
-  relativePath: string;
-  content: string;
-}): Promise<void> {
-  const { page, gate, filePath, relativePath, content } = input;
-  // Recreate the observed race without faking file state: the daemon publishes the
-  // deletion, then a real read succeeds after the replacement while its ready event waits.
-  await gate.waitForFileSubscription(relativePath);
-  gate.holdFileReads(relativePath);
-  await unlink(filePath);
-  await gate.waitForHeldFileRead();
-  await expect(fileCallout(page)).toHaveCount(0);
-  gate.releaseHeldFileRead();
-  await expectOnlyFileCallout(page, "File deleted on disk");
-  gate.holdNextReadyFileUpdate(relativePath);
-  await writeFile(filePath, content, "utf8");
-  await gate.waitForHeldReadyFileUpdate();
-  await expect.poll(() => readFile(filePath, "utf8")).toBe(content);
-}
-
 async function expectOnlyFileCallout(page: Page, title: string): Promise<void> {
   await expect(fileCallout(page)).toHaveCount(1);
   await expect(fileCallout(page)).toContainText(title);
   await expect(filePane(page).getByText(title, { exact: true })).toHaveCount(1);
 }
 
-async function expectCleanReplacementCanReload(page: Page): Promise<void> {
-  await expectOnlyFileCallout(page, "Changed on disk");
-  await expect(filePane(page).getByText("File deleted on disk", { exact: true })).toHaveCount(0);
-  await expect(fileCallout(page).getByRole("button", { name: "Overwrite" })).toHaveCount(0);
-  await expect(fileCallout(page).getByRole("button", { name: "Reload" })).toBeEnabled();
-  await fileCallout(page).getByRole("button", { name: "Reload" }).click();
-  await expect(filePane(page).getByText("After", { exact: true })).toBeVisible();
-  await expect(fileCallout(page)).toHaveCount(0);
-}
-
 async function expectDeletedFileNotice(page: Page): Promise<void> {
   await expectOnlyFileCallout(page, "File deleted on disk");
   await expect(fileCallout(page)).toContainText("The open copy is preserved.");
@@ -140,7 +107,7 @@ test.describe("Workspace file change conflicts", () => {
       relativePath,
       content: "const preserved = true;\n",
     });
-    await gate.waitForFileSubscription(relativePath);
+    await expect(visibleEditor(page)).toContainText("const preserved = true;");
     await recordFileCallouts(page);
 
     await restoreFileAfterWatcherObservedTemporaryAbsence({ gate, filePath, relativePath });
@@ -189,162 +156,79 @@ test.describe("Workspace file change conflicts", () => {
       relativePath,
       content: "const before = true;\n",
     });
-    await gate.waitForFileSubscription(relativePath);
+    await expect(visibleEditor(page)).toContainText("const before = true;");
     await recordFileCallouts(page);
-    gate.holdFileReads(relativePath);
+    gate.holdNextReadyFileUpdate(relativePath);
 
     await replaceEditorText(page, "const saved = true;\n");
     await expect.poll(() => readFile(filePath, "utf8")).toContain("const saved = true;");
-    await gate.waitForHeldFileRead();
+    await gate.waitForHeldReadyFileUpdate();
+    gate.releaseHeldReadyFileUpdate();
 
     await expect(visibleEditor(page)).toContainText("const saved = true;");
     await expect(fileCallout(page)).toHaveCount(0);
     await expectNoFileCalloutWasRendered(page);
-    gate.releaseHeldFileRead();
   });
 
-  test("a clean file replaced on disk offers one working reload action", async ({
+  test("a viewed file deleted and written back shows the new file", async ({
     page,
     withWorkspace,
   }) => {
-    const gate = await installDaemonWebSocketGate(page);
     const filePath = await openTrackedFile(page, withWorkspace, {
       prefix: "file-clean-replacement-",
       relativePath: "inventory.md",
       content: "# Before\n",
     });
     await expect(filePane(page).getByText("Before", { exact: true })).toBeVisible();
-    await replaceFileAfterDeletionWasObserved({
-      page,
-      gate,
-      filePath,
-      relativePath: "inventory.md",
-      content: "# After\n",
-    });
-    gate.releaseHeldReadyFileUpdate();
-    await expectCleanReplacementCanReload(page);
+
+    await unlink(filePath);
+    await expect(filePane(page).getByText("The file was deleted.", { exact: true })).toBeVisible();
+    await writeFile(filePath, "# After\n", "utf8");
+
+    await expect(filePane(page).getByText("After", { exact: true })).toBeVisible();
+    await expect(fileCallout(page)).toHaveCount(0);
   });
 
-  test("a deleted file shows one explanatory notice and no resolution actions", async ({
+  test("a deleted file keeps the open copy with one notice and no resolution actions", async ({
     page,
     withWorkspace,
   }) => {
     const filePath = await openTrackedFile(page, withWorkspace, {
       prefix: "file-deleted-",
-      relativePath: "deleted.md",
-      content: "# Present\n",
+      relativePath: "deleted.ts",
+      content: "const present = true;\n",
     });
-    await expect(filePane(page).getByText("Present", { exact: true })).toBeVisible();
+    await expect(visibleEditor(page)).toContainText("const present = true;");
     await recordFileCallouts(page);
     await unlink(filePath);
     await expectDeletedFileNotice(page);
     await expectFileCalloutWasRendered(page, "File deleted on disk");
+    await expect(visibleEditor(page)).toContainText("const present = true;");
   });
 
-  test("a file check error offers a working retry", async ({ page, withWorkspace }) => {
-    const gate = await installDaemonWebSocketGate(page);
-    const relativePath = "retry.md";
-    const filePath = await openTrackedFile(page, withWorkspace, {
-      prefix: "file-check-retry-",
-      relativePath,
-      content: "# Before\n",
-    });
-    await gate.waitForFileSubscription(relativePath);
-    await expect(filePane(page).getByText("Before", { exact: true })).toBeVisible();
-
-    await unlink(filePath);
-    await mkdir(filePath);
-    await expectOnlyFileCallout(page, "Couldn't check file on disk");
-    await expect(fileCallout(page).getByRole("button", { name: "Retry" })).toBeEnabled();
-    await expect(fileCallout(page).getByRole("button", { name: "Reload" })).toHaveCount(0);
-    await expect(fileCallout(page).getByRole("button", { name: "Overwrite" })).toHaveCount(0);
-
-    gate.holdNextReadyFileUpdate(relativePath);
-    await rm(filePath, { recursive: true });
-    await writeFile(filePath, "# After\n", "utf8");
-    await gate.waitForHeldReadyFileUpdate();
-    gate.holdFileReads(relativePath);
-    await fileCallout(page).getByRole("button", { name: "Retry" }).click();
-    await gate.waitForHeldFileRead();
-    await expect(fileCallout(page).getByRole("button", { name: "Retry" })).toBeDisabled();
-    gate.releaseHeldFileRead();
-    await expectCleanReplacementCanReload(page);
-    gate.releaseHeldReadyFileUpdate();
-  });
-
-  test("retry clears a transient error when the file is unchanged", async ({
+  test("a path that stops being a file keeps the open copy and follows the file back", async ({
     page,
     withWorkspace,
   }) => {
     const gate = await installDaemonWebSocketGate(page);
-    const relativePath = "unchanged.md";
+    const relativePath = "retry.ts";
     const filePath = await openTrackedFile(page, withWorkspace, {
-      prefix: "file-check-unchanged-",
+      prefix: "file-check-error-",
       relativePath,
-      content: "# Unchanged\n",
+      content: "const before = true;\n",
     });
-    const parkedPath = `${filePath}.parked`;
-    await gate.waitForFileSubscription(relativePath);
-    await expect(filePane(page).getByText("Unchanged", { exact: true })).toBeVisible();
+    await expect(visibleEditor(page)).toContainText("const before = true;");
 
-    await rename(filePath, parkedPath);
+    await unlink(filePath);
     await mkdir(filePath);
-    await expectOnlyFileCallout(page, "Couldn't check file on disk");
+    await gate.waitForFileUpdate(relativePath, "error");
+    await expect(visibleEditor(page)).toContainText("const before = true;");
 
-    gate.holdNextReadyFileUpdate(relativePath);
     await rm(filePath, { recursive: true });
-    await rename(parkedPath, filePath);
-    await gate.waitForHeldReadyFileUpdate();
-    await fileCallout(page).getByRole("button", { name: "Retry" }).click();
+    await writeFile(filePath, "const after = true;\n", "utf8");
 
+    await expect(visibleEditor(page)).toContainText("const after = true;");
     await expect(fileCallout(page)).toHaveCount(0);
-    await expect(filePane(page).getByText("Changed on disk", { exact: true })).toHaveCount(0);
-    gate.releaseHeldReadyFileUpdate();
-  });
-
-  test("a read-only file error preserves its message and offers retry", async ({
-    page,
-    withWorkspace,
-  }) => {
-    const gate = await installDaemonWebSocketGate(page);
-    const relativePath = "artifact.bin";
-    const binaryContent = new Uint8Array([0, 1, 2, 3, 255]);
-    const filePath = await openTrackedFile(page, withWorkspace, {
-      prefix: "file-read-only-retry-",
-      relativePath,
-      content: binaryContent,
-    });
-    await gate.waitForFileSubscription(relativePath);
-    await expect(
-      filePane(page).getByText("Binary preview unavailable", { exact: true }),
-    ).toBeVisible();
-
-    await unlink(filePath);
-    await mkdir(filePath);
-    await expect(
-      filePane(page).getByText("Requested path is not a file", { exact: true }),
-    ).toBeVisible();
-    await expect(filePane(page).getByRole("button", { name: "Retry" })).toBeEnabled();
-
-    gate.holdNextReadyFileUpdate(relativePath);
-    await rm(filePath, { recursive: true });
-    await writeFile(filePath, binaryContent);
-    await gate.waitForHeldReadyFileUpdate();
-    gate.holdFileReads(relativePath);
-    await filePane(page).getByRole("button", { name: "Retry" }).click();
-    await gate.waitForHeldFileRead();
-    await expect(
-      filePane(page).getByText("Requested path is not a file", { exact: true }),
-    ).toHaveCount(0);
-    gate.releaseHeldFileRead();
-
-    await expect(
-      filePane(page).getByText("Binary preview unavailable", { exact: true }),
-    ).toBeVisible();
-    await expect(
-      filePane(page).getByText("Requested path is not a file", { exact: true }),
-    ).toHaveCount(0);
-    gate.releaseHeldReadyFileUpdate();
   });
 
   test("a changed file with local edits offers overwrite and a working reload", async ({

packages/app/e2e/browser/file-editing.spec.ts

@@ -55,6 +55,10 @@ async function openWorkspaceFile(page: Page, filename: string): Promise<void> {
   await expectFileTabOpen(page, filename);
 }
 
+function filePanelSwitcher(page: Page) {
+  return page.getByTestId("file-panel-switcher").filter({ visible: true });
+}
+
 function htmlPreview(page: Page) {
   return {
     host: page.getByTestId("file-html-preview"),
@@ -62,11 +66,9 @@ function htmlPreview(page: Page) {
   };
 }
 
-async function selectFileView(page: Page, view: "Preview" | "Source"): Promise<void> {
-  const option = page.getByTestId("file-panel-bar").getByRole("button", {
-    name: view,
-    exact: true,
-  });
+/** Switches the file tab to one of its panels from the bar's switcher. */
+async function selectFilePanel(page: Page, title: string): Promise<void> {
+  const option = filePanelSwitcher(page).getByRole("button", { name: title, exact: true });
   await option.click();
   await expect(option).toHaveAttribute("aria-selected", "true");
 }
@@ -128,7 +130,7 @@ test.describe("CodeMirror workspace file editing", () => {
         await returnToAssistant(page, session.agentId);
         await openAssistantMarkdownLink(page, "Missing capture");
         await expectFileTabOpen(page, ".dev/tablet-review/missing.png");
-        await expect(page.getByText(/ENOENT/)).toBeVisible();
+        await expect(page.getByText("File not found", { exact: true })).toBeVisible();
         await expect(page.getByRole("button", { name: "Retry", exact: true })).toBeVisible();
       });
     } finally {
@@ -317,11 +319,7 @@ test.describe("CodeMirror workspace file editing", () => {
       title: "Unsupported large source",
       initialPrompt: "Generate a title and a git branch name. Return JSON only.",
     });
-    await writeFile(
-      path.join(session.cwd, "too-large.txt"),
-      Buffer.alloc(51 * 1024 * 1024),
-      "utf8",
-    );
+    await writeFile(path.join(session.cwd, "too-large.txt"), "x".repeat(51 * 1024 * 1024), "utf8");
 
     try {
       await openAgentRoute(page, session);
@@ -484,9 +482,9 @@ test.describe("CodeMirror workspace file editing", () => {
       relativePath,
     );
     await expect(page.getByTestId("file-panel-bar")).not.toContainText("visuals.md");
-    const modeControl = page.getByTestId("file-preview-mode");
+    const modeControl = filePanelSwitcher(page);
     await expect(modeControl).toBeVisible();
-    await selectFileView(page, "Source");
+    await selectFilePanel(page, "Source");
 
     const editorHost = page.getByTestId("file-source-editor");
     const content = editor(page);
@@ -548,7 +546,7 @@ test.describe("CodeMirror workspace file editing", () => {
     );
     await workspace.navigateTo();
     await openWorkspaceFile(page, "notes.md");
-    await selectFileView(page, "Source");
+    await selectFilePanel(page, "Source");
 
     const markdownScroller = page
       .getByTestId("file-source-editor")
@@ -680,7 +678,7 @@ test.describe("CodeMirror workspace file editing", () => {
     await expect(page.getByTestId("workspace-tab-modified-file_draft.ts")).toBeVisible();
   });
 
-  test("refreshes Markdown and images while preserving Preview and Source behavior", async ({
+  test("refreshes Markdown and images while switching between Markdown and Source", async ({
     page,
     withWorkspace,
   }) => {
@@ -695,15 +693,15 @@ test.describe("CodeMirror workspace file editing", () => {
 
     const visibleFilePane = page.getByTestId("workspace-file-pane").filter({ visible: true });
     await expect(visibleFilePane.getByText("First heading", { exact: true })).toBeVisible();
-    await expect(page.getByRole("button", { name: "Preview", exact: true })).toBeVisible();
+    await expect(filePanelSwitcher(page).getByRole("button", { name: "Markdown" })).toBeVisible();
     await writeFile(markdownPath, "# Updated heading\n", "utf8");
     await expect(visibleFilePane.getByText("Updated heading", { exact: true })).toBeVisible();
 
-    await selectFileView(page, "Source");
+    await selectFilePanel(page, "Source");
     await expect(page.getByTestId("file-source-editor")).toBeVisible();
     await replaceEditorText(page, "# Saved from source\n");
     await expect.poll(() => readFile(markdownPath, "utf8")).toBe("# Saved from source\n");
-    await selectFileView(page, "Preview");
+    await selectFilePanel(page, "Markdown");
     await expect(visibleFilePane.getByText("Saved from source", { exact: true })).toBeVisible();
 
     await openWorkspaceFile(page, "pixel.png");
@@ -786,10 +784,10 @@ test.describe("CodeMirror workspace file editing", () => {
     );
     await expect(preview.document.getByRole("heading", { name: "Updated plan" })).toBeVisible();
 
-    await selectFileView(page, "Source");
+    await selectFilePanel(page, "Source");
     await expect(page.getByTestId("file-source-editor")).toBeVisible();
     await expect(preview.host).toHaveCount(0);
-    await selectFileView(page, "Preview");
+    await selectFilePanel(page, "HTML");
     await expect(preview.host).toBeVisible();
   });
 

packages/app/e2e/browser/folder-links.spec.ts

@@ -14,8 +14,9 @@ async function openMarkdownPreview(page: Page) {
   await openFileFromExplorer(page, "README.md");
   await expectFileTabOpen(page, "README.md");
   await page
-    .getByTestId("file-panel-bar")
-    .getByRole("button", { name: "Preview", exact: true })
+    .getByTestId("file-panel-switcher")
+    .filter({ visible: true })
+    .getByRole("button", { name: "Markdown", exact: true })
     .click();
   await ensureWorkspaceAgentPaneVisible(page);
 }

packages/app/e2e/browser/markdown-relative-links.spec.ts

@@ -0,0 +1,47 @@
+import { mkdir, writeFile } from "node:fs/promises";
+import path from "node:path";
+import { expect, test, type Page } from "../support/fixtures";
+import {
+  expandFolder,
+  openFileExplorer,
+  openFileFromExplorer,
+} from "../support/helpers/file-explorer";
+
+async function openNestedGuide(page: Page): Promise<void> {
+  await openFileExplorer(page);
+  await expandFolder(page, "docs");
+  await openFileFromExplorer(page, "guide.md");
+}
+
+async function followDetailsLink(page: Page): Promise<void> {
+  await page
+    .getByTestId("markdown-preview-frame")
+    .getByRole("link", { name: "Details", exact: true })
+    .click();
+}
+
+test("Markdown preview resolves a relative link from the document directory", async ({
+  page,
+  withWorkspace,
+}) => {
+  const workspace = await withWorkspace({ prefix: "markdown-relative-links-" });
+  await mkdir(path.join(workspace.repoPath, "docs/guide"), { recursive: true });
+  await writeFile(
+    path.join(workspace.repoPath, "docs/guide.md"),
+    "# Guide\n\n[Details](guide/details.md)\n",
+  );
+  await writeFile(
+    path.join(workspace.repoPath, "docs/guide/details.md"),
+    "# Nested details destination\n",
+  );
+  await workspace.navigateTo();
+
+  await openNestedGuide(page);
+  await followDetailsLink(page);
+
+  await expect(
+    page
+      .getByTestId("markdown-preview-frame")
+      .getByText("Nested details destination", { exact: true }),
+  ).toBeVisible();
+});

packages/app/e2e/browser/plugin-buttons.spec.ts

@@ -1,3 +1,4 @@
+import { verifyPluginToolTranslations } from "../support/helpers/plugin-translations";
 import { test } from "../support/fixtures";
 import { withButtonShowcase } from "../support/helpers/plugin-buttons";
 
@@ -13,3 +14,10 @@ test("plugin header and composer buttons share actions, menus, content, and upda
     await buttons.hideAndUnloadOpenButtons();
   });
 });
+
+test("plugin tooltips and menu labels follow app language with a panel draft open", async ({
+  page,
+}, info) => {
+  test.setTimeout(180_000);
+  await verifyPluginToolTranslations(page, info);
+});

packages/app/e2e/browser/plugin-file-panel-examples.spec.ts

@@ -0,0 +1,279 @@
+import { execFileSync } from "node:child_process";
+import { readFile, writeFile } from "node:fs/promises";
+import path from "node:path";
+import type { Frame, TestInfo } from "@playwright/test";
+import { expect, test, type Page } from "../support/fixtures";
+import { copyPluginExample } from "../support/helpers/plugin-fixture";
+import { connectNewWorkspaceDaemonClient } from "../support/helpers/new-workspace";
+import { seedWorkspace } from "../support/helpers/seed-client";
+import { gotoWorkspace } from "../support/helpers/launcher";
+import { installDaemonWebSocketGate } from "../support/helpers/daemon-websocket-gate";
+import {
+  openFileExplorer,
+  openFileFromExplorer,
+  expectFileTabOpen,
+} from "../support/helpers/file-explorer";
+
+// Full Chromium includes the PDF viewer; the default headless shell does not.
+test.use({ channel: "chromium" });
+
+function samplePdf() {
+  const stream = "BT /F1 24 Tf 72 720 Td (Paseo PDF panel example) Tj ET";
+  const objects = [
+    "<< /Type /Catalog /Pages 2 0 R >>",
+    "<< /Type /Pages /Kids [3 0 R] /Count 1 >>",
+    "<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] /Resources << /Font << /F1 4 0 R >> >> /Contents 5 0 R >>",
+    "<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>",
+    `<< /Length ${stream.length} >>\nstream\n${stream}\nendstream`,
+  ];
+  let pdf = "%PDF-1.4\n%\u0000\u00ff\n";
+  const offsets = objects.map((object, index) => {
+    const offset = Buffer.byteLength(pdf);
+    pdf += `${index + 1} 0 obj\n${object}\nendobj\n`;
+    return offset;
+  });
+  const xref = Buffer.byteLength(pdf);
+  pdf += `xref\n0 6\n0000000000 65535 f \n${offsets.map((offset) => `${String(offset).padStart(10, "0")} 00000 n \n`).join("")}`;
+  pdf += `trailer\n<< /Size 6 /Root 1 0 R >>\nstartxref\n${xref}\n%%EOF\n`;
+  return pdf;
+}
+
+async function openFile(page: Page, name: string) {
+  await openFileFromExplorer(page, name);
+  await expectFileTabOpen(page, name);
+}
+
+const WIDE = { width: 1280, height: 900 };
+const COMPACT = { width: 390, height: 844 };
+
+async function capture(page: Page, testInfo: TestInfo, name: string) {
+  const file = testInfo.outputPath(`${name}.png`);
+  await page.screenshot({ path: file });
+  await testInfo.attach(name, { path: file, contentType: "image/png" });
+}
+
+/** Captures the current state wide, then compact once `ready` holds there, and returns to wide. */
+async function captureWideAndCompact(
+  page: Page,
+  testInfo: TestInfo,
+  name: string,
+  ready: () => Promise<void>,
+) {
+  await capture(page, testInfo, `${name}-wide`);
+  // The shell survives the breakpoint, so the previous layout's copy can still be on screen right
+  // after a resize. Check `ready` only once the shell reports the new layout.
+  await page.setViewportSize(COMPACT);
+  await expect(page.getByTestId("compact-shell")).toBeVisible();
+  await ready();
+  await capture(page, testInfo, `${name}-compact`);
+  await page.setViewportSize(WIDE);
+  await expect(page.getByTestId("wide-shell")).toBeVisible();
+  await ready();
+}
+
+function filePanelSwitcher(page: Page) {
+  return page.getByTestId("file-panel-switcher").filter({ visible: true });
+}
+
+/** Turns on vim keybindings without discarding settings the test writes later. */
+async function enableVimKeybindings(page: Page) {
+  await page.addInitScript(() => {
+    const key = "@paseo:app-settings";
+    const settings = JSON.parse(localStorage.getItem(key) ?? "{}");
+    localStorage.setItem(key, JSON.stringify({ ...settings, vimKeybindings: true }));
+  });
+}
+
+async function chooseRichMarkdown(page: Page) {
+  await page.getByRole("radio", { name: "Rich Markdown — markdown-panel", exact: true }).click();
+  await page.getByRole("checkbox", { name: "Don't ask me again", exact: true }).click();
+  await page.getByRole("button", { name: "Use", exact: true }).click();
+}
+
+async function replaceMarkdown(page: Page, text: string) {
+  await page.getByRole("textbox", { name: "Rich Markdown editor", exact: true }).fill(text);
+}
+
+async function selectPanel(page: Page, title: string) {
+  await filePanelSwitcher(page).getByRole("button", { name: title, exact: true }).click();
+}
+
+async function expectPanels(page: Page, titles: string[]) {
+  for (const title of titles) {
+    await expect(
+      filePanelSwitcher(page).getByRole("button", { name: title, exact: true }),
+    ).toBeInViewport({ ratio: 1 });
+  }
+}
+
+/** The browser's PDF viewer in the mounted frame; a remounted pane leaves old frames detached. */
+async function pdfViewer(page: Page): Promise<Frame> {
+  const viewerUrl = /^chrome-extension:\/\/[^/]+\/index\.html$/;
+  const find = () =>
+    page.frames().find((frame) => !frame.isDetached() && viewerUrl.test(frame.url())) ?? null;
+  await expect.poll(() => find() !== null).toBe(true);
+  return find()!;
+}
+
+async function expectPdfViewerReady(page: Page) {
+  // A narrow viewer collapses its toolbar to Print and More actions.
+  const viewer = await pdfViewer(page);
+  await expect(viewer.getByRole("button", { name: "Print", exact: true })).toBeEnabled();
+}
+
+async function expectMarkdownEditor(page: Page, text: string) {
+  const editor = page.getByRole("textbox", { name: "Rich Markdown editor", exact: true });
+  await expect(editor).toBeVisible();
+  await expect(editor).toContainText(text);
+  await expect(editor).toBeInViewport({ ratio: 1 });
+  // Side by side on a wide screen; on a phone three panels do not fit, so the switcher is a menu.
+  await expect(filePanelSwitcher(page)).toContainText("Rich Markdown");
+  await expect(filePanelSwitcher(page)).toBeInViewport({ ratio: 1 });
+}
+
+test("directory examples mount the PDF frame and write Markdown through the file handle", async ({
+  page,
+}, testInfo) => {
+  test.setTimeout(180_000);
+  const pdf = await copyPluginExample("pdf-panel");
+  const markdown = await copyPluginExample("markdown-panel");
+  execFileSync(
+    process.platform === "win32" ? "npm.cmd" : "npm",
+    ["install", "--ignore-scripts", "--no-audit", "--no-fund"],
+    { cwd: markdown.directory, stdio: "pipe" },
+  );
+  const workspace = await seedWorkspace({
+    repoPrefix: "file-panel-examples-",
+    repo: {
+      files: [
+        {
+          path: "notes.md",
+          content: "# Markdown panel example\n\nEdit **Markdown** through Paseo.\n",
+        },
+        { path: "second.md", content: "# Remembered panel\n" },
+        { path: "report.pdf", content: samplePdf() },
+      ],
+    },
+  });
+  const client = await connectNewWorkspaceDaemonClient({ ownProjects: false });
+  const previous = await client.getDaemonConfig();
+  try {
+    await client.patchDaemonConfig({ pluginsEnabled: true });
+    await client.installDirectoryPlugin(pdf.directory);
+    await client.installDirectoryPlugin(markdown.directory);
+    await enableVimKeybindings(page);
+    await page.setViewportSize(WIDE);
+    const gate = await installDaemonWebSocketGate(page);
+    await gotoWorkspace(page, workspace.workspaceId);
+    await openFileExplorer(page);
+    await openFile(page, "report.pdf");
+    await expect(page.getByTitle("Document preview", { exact: true })).toHaveAttribute(
+      "src",
+      /^blob:/,
+    );
+    await expect(page.getByTitle("Document preview", { exact: true })).not.toHaveAttribute(
+      "sandbox",
+    );
+    const documentUrl = await page
+      .getByTitle("Document preview", { exact: true })
+      .getAttribute("src");
+    expect(
+      await page.evaluate(
+        async (url) => (await fetch(url!)).blob().then((blob) => blob.type),
+        documentUrl,
+      ),
+    ).toBe("application/pdf");
+    await expectPdfViewerReady(page);
+    await expect(
+      (await pdfViewer(page)).getByRole("textbox", { name: "Page number", exact: true }),
+    ).toHaveValue("1");
+    await captureWideAndCompact(page, testInfo, "pdf-example", async () => {
+      await expect(page.getByTitle("Document preview", { exact: true })).toBeInViewport();
+      await expectPdfViewerReady(page);
+    });
+
+    await openFile(page, "notes.md");
+    await expect(page.getByRole("radio", { name: "Markdown — Paseo", exact: true })).toBeChecked();
+    await expect(
+      page.getByRole("radio", { name: "Rich Markdown — markdown-panel", exact: true }),
+    ).toBeVisible();
+    await expect(page.getByRole("radio", { name: "Source — Paseo", exact: true })).toBeVisible();
+    await captureWideAndCompact(page, testInfo, "markdown-example-picker", async () => {
+      // The previous layout's picker animates out (the sheet slides down, the dialog fades), so
+      // both pickers are mounted for a moment after a resize.
+      await expect(page.getByRole("button", { name: "Use", exact: true })).toHaveCount(1);
+      await expect(page.getByRole("button", { name: "Use", exact: true })).toBeInViewport({
+        ratio: 1,
+      });
+    });
+    await chooseRichMarkdown(page);
+    await expect(page.getByRole("textbox", { name: "Rich Markdown editor" })).toContainText(
+      "Markdown panel example",
+    );
+    gate.holdNextClientRequest("fs.file.write.request");
+    await replaceMarkdown(page, "# Edited by Rich Markdown\n\nSaved by the panel.\n");
+    await gate.waitForHeldClientRequest();
+    await expect(page.getByTestId("workspace-tab-modified-file_notes.md")).toBeVisible();
+    await capture(page, testInfo, "markdown-example-dirty-wide");
+    gate.releaseHeldClientRequest();
+    await expect
+      .poll(() => readFile(path.join(workspace.repoPath, "notes.md"), "utf8"))
+      .toBe("# Edited by Rich Markdown\n\nSaved by the panel.\n");
+    await expect(page.getByTestId("workspace-tab-modified-file_notes.md")).toBeHidden();
+    await expectPanels(page, ["Rich Markdown", "Markdown", "Source"]);
+    await captureWideAndCompact(page, testInfo, "markdown-example-rich-markdown", async () => {
+      await expectMarkdownEditor(page, "Edited by Rich Markdown");
+    });
+
+    // Source is Paseo's editor; its cursor and vim mode are in its own status row.
+    await selectPanel(page, "Source");
+    const source = page.getByTestId("file-source-editor").filter({ visible: true });
+    await expect(source.locator(".cm-content")).toContainText("Edited by Rich Markdown");
+    await source.locator(".cm-line").nth(2).click();
+    const bar = page.getByTestId("file-source-status").filter({ visible: true });
+    await expect(bar.getByText("NORMAL", { exact: true })).toBeVisible();
+    await expect(bar.getByText(/^Ln 3, Col \d+$/)).toBeVisible();
+    await capture(page, testInfo, "markdown-example-source-wide");
+    // The phone layout mounts the tab anew, so it opens the remembered panel; its menu offers Source.
+    await page.setViewportSize(COMPACT);
+    await expect(filePanelSwitcher(page)).toHaveText("Rich Markdown");
+    await filePanelSwitcher(page).click();
+    await page.getByRole("menuitem", { name: "Source", exact: true }).click();
+    await expect(filePanelSwitcher(page)).toHaveText("Source");
+    await source.locator(".cm-line").nth(2).click();
+    await expect(bar.getByText("NORMAL", { exact: true })).toBeInViewport();
+    await expect(bar.getByText(/^Ln 3, Col \d+$/)).toBeInViewport();
+    await capture(page, testInfo, "markdown-example-source-compact");
+    await page.setViewportSize(WIDE);
+    await selectPanel(page, "Rich Markdown");
+    await writeFile(path.join(workspace.repoPath, "notes.md"), "# External update\n");
+    await expect(page.getByRole("textbox", { name: "Rich Markdown editor" })).toHaveText(
+      "# External update",
+    );
+    await replaceMarkdown(page, "# Local edit\n");
+    await writeFile(path.join(workspace.repoPath, "notes.md"), "# Conflicting external edit\n");
+    await expect(page.getByTestId("rich-markdown-conflict")).toBeVisible();
+    await capture(page, testInfo, "markdown-example-conflict-wide");
+    await page.getByRole("button", { name: "Overwrite", exact: true }).click();
+    await expect
+      .poll(() => readFile(path.join(workspace.repoPath, "notes.md"), "utf8"))
+      .toBe("# Local edit\n");
+
+    await openFile(page, "second.md");
+    await expect(page.getByRole("textbox", { name: "Rich Markdown editor" })).toContainText(
+      "Remembered panel",
+    );
+    await expect(page.getByText("Open .md files with", { exact: true })).toBeHidden();
+    await page.setViewportSize(COMPACT);
+    await expectMarkdownEditor(page, "Remembered panel");
+    await expect(filePanelSwitcher(page)).toHaveText("Rich Markdown");
+  } finally {
+    await client.removePlugin("pdf-panel");
+    await client.removePlugin("markdown-panel");
+    await client.patchDaemonConfig({ pluginsEnabled: previous.config.pluginsEnabled ?? false });
+    await client.close();
+    await workspace.cleanup();
+    await pdf.cleanup();
+    await markdown.cleanup();
+  }
+});

packages/app/e2e/browser/plugin-file-panel-picker.spec.ts

@@ -0,0 +1,156 @@
+import type { TestInfo } from "@playwright/test";
+import { expect, test, type Page } from "../support/fixtures";
+import { seedWorkspace } from "../support/helpers/seed-client";
+import { gotoWorkspace } from "../support/helpers/launcher";
+import { expectFileTabOpen, openFileExplorer } from "../support/helpers/file-explorer";
+import {
+  BUILTIN_MARKDOWN_OPTION,
+  MARKDOWN_PANEL_ID,
+  PLUGIN_MARKDOWN_OPTION,
+  expectBuiltinMarkdown,
+  expectPluginMarkdown,
+  filePanelPicker,
+  installMarkdownPanelPlugin,
+  openMarkdown,
+  storedFilePanelAssociations,
+} from "../support/helpers/markdown-file-panel-plugin";
+
+async function choosePanel(page: Page, option: string, options: { remember: boolean }) {
+  await page.getByRole("radio", { name: option, exact: true }).click();
+  if (options.remember) {
+    await page.getByRole("checkbox", { name: "Don't ask me again", exact: true }).click();
+  }
+  await page.getByRole("button", { name: "Use", exact: true }).click();
+  await expect(filePanelPicker(page)).toBeHidden();
+}
+
+async function openWithFromTabMenu(page: Page, name: string, option: string) {
+  await page.getByTestId(`workspace-tab-file_${name}`).first().click({ button: "right" });
+  await page.getByRole("menuitem", { name: "Open with…" }).hover();
+  await page.getByRole("menuitem", { name: option }).click();
+}
+
+async function toggleAlwaysUseFromFileBar(page: Page) {
+  await page.getByTestId("file-panel-bar-menu").filter({ visible: true }).click();
+  await page.getByRole("menuitem", { name: "Always use for .md" }).click();
+}
+
+function filePanelSwitcher(page: Page) {
+  return page.getByTestId("file-panel-switcher").filter({ visible: true });
+}
+
+async function expectSwitcherPanels(page: Page, titles: string[]) {
+  await expect(filePanelSwitcher(page).getByRole("button")).toHaveText(titles);
+}
+
+async function capture(page: Page, testInfo: TestInfo, name: string) {
+  const file = testInfo.outputPath(`${name}.png`);
+  await page.screenshot({ path: file });
+  await testInfo.attach(name, { path: file, contentType: "image/png" });
+}
+
+test("opens Markdown with the built-in panel and Source beside it without asking", async ({
+  page,
+}, testInfo) => {
+  const workspace = await seedWorkspace({
+    repoPrefix: "file-panel-builtins-",
+    repo: { files: [{ path: "notes.md", content: "# notes heading\n" }] },
+  });
+  try {
+    await page.setViewportSize({ width: 1280, height: 900 });
+    await gotoWorkspace(page, workspace.workspaceId);
+    await openFileExplorer(page);
+    await openMarkdown(page, "notes.md");
+    await expectBuiltinMarkdown(page, "notes heading");
+    await expectSwitcherPanels(page, ["Markdown", "Source"]);
+    await expect(filePanelPicker(page)).toBeHidden();
+    await capture(page, testInfo, "file-panel-builtins-wide");
+
+    await filePanelSwitcher(page).getByRole("button", { name: "Source", exact: true }).click();
+    await expect(page.getByTestId("file-source-editor").filter({ visible: true })).toBeVisible();
+    await filePanelSwitcher(page).getByRole("button", { name: "Markdown", exact: true }).click();
+    await expectBuiltinMarkdown(page, "notes heading");
+
+    await page.setViewportSize({ width: 390, height: 844 });
+    await expectBuiltinMarkdown(page, "notes heading");
+    await expect(
+      filePanelSwitcher(page).getByRole("button", { name: "Source", exact: true }),
+    ).toBeInViewport({ ratio: 1 });
+    await expect(filePanelPicker(page)).toBeHidden();
+    await capture(page, testInfo, "file-panel-builtins-compact");
+  } finally {
+    await workspace.cleanup();
+  }
+});
+
+test("asks once which panel opens Markdown and remembers it when told to", async ({
+  page,
+}, testInfo) => {
+  test.setTimeout(120_000);
+  const workspace = await seedWorkspace({
+    repoPrefix: "file-panel-picker-",
+    repo: {
+      files: ["first", "second", "third", "fourth"].map((name) => ({
+        path: `${name}.md`,
+        content: `# ${name} heading\n`,
+      })),
+    },
+  });
+  const plugin = await installMarkdownPanelPlugin();
+  try {
+    await page.setViewportSize({ width: 1280, height: 900 });
+    await gotoWorkspace(page, workspace.workspaceId);
+    await openFileExplorer(page);
+
+    // First open: the built-in renders under the picker.
+    await openMarkdown(page, "first.md");
+    await expect(filePanelPicker(page)).toBeVisible();
+    await expect(page.getByRole("radio", { name: BUILTIN_MARKDOWN_OPTION })).toBeChecked();
+    await expect(page.getByRole("radio", { name: PLUGIN_MARKDOWN_OPTION })).not.toBeChecked();
+    await expectBuiltinMarkdown(page, "first heading");
+    await capture(page, testInfo, "file-panel-picker-wide");
+
+    // Don't ask me again: the plugin renders and later opens use it silently.
+    await choosePanel(page, PLUGIN_MARKDOWN_OPTION, { remember: true });
+    await expectPluginMarkdown(page, "first.md");
+    expect(await storedFilePanelAssociations(page)).toEqual({ "ext:md": MARKDOWN_PANEL_ID });
+    await openMarkdown(page, "second.md");
+    await expectPluginMarkdown(page, "second.md");
+    await expect(filePanelPicker(page)).toBeHidden();
+
+    // Forgetting from the file bar keeps the tab on the plugin.
+    await toggleAlwaysUseFromFileBar(page);
+    await expect.poll(() => storedFilePanelAssociations(page)).toEqual({});
+    await expectPluginMarkdown(page, "second.md");
+
+    // An unremembered choice applies to this tab only; the next open asks again.
+    await openMarkdown(page, "third.md");
+    await expect(filePanelPicker(page)).toBeVisible();
+    await choosePanel(page, PLUGIN_MARKDOWN_OPTION, { remember: false });
+    await expectPluginMarkdown(page, "third.md");
+    expect(await storedFilePanelAssociations(page)).toEqual({});
+
+    // "Open with…" switches the open tab back to the built-in in place.
+    await openWithFromTabMenu(page, "third.md", BUILTIN_MARKDOWN_OPTION);
+    await expectBuiltinMarkdown(page, "third heading");
+    await expectFileTabOpen(page, "third.md");
+
+    // Dismissing keeps the built-in; reopening the tab after a reload asks again.
+    await openMarkdown(page, "fourth.md");
+    await expect(filePanelPicker(page)).toBeVisible();
+    await page.keyboard.press("Escape");
+    await expect(filePanelPicker(page)).toBeHidden();
+    await expectBuiltinMarkdown(page, "fourth heading");
+
+    await page.setViewportSize({ width: 390, height: 844 });
+    await page.reload();
+    await expect(filePanelPicker(page)).toBeVisible({ timeout: 30_000 });
+    await expect(page.getByRole("button", { name: "Use", exact: true })).toBeInViewport({
+      ratio: 1,
+    });
+    await capture(page, testInfo, "file-panel-picker-compact");
+  } finally {
+    await plugin.uninstall();
+    await workspace.cleanup();
+  }
+});

packages/app/e2e/browser/plugin-file-panel-settings.spec.ts

@@ -0,0 +1,150 @@
+import type { TestInfo } from "@playwright/test";
+import { expect, test, type Page } from "../support/fixtures";
+import { openSettings } from "../support/helpers/app";
+import { openFileExplorer } from "../support/helpers/file-explorer";
+import { gotoWorkspace } from "../support/helpers/launcher";
+import {
+  BUILTIN_MARKDOWN_OPTION,
+  MARKDOWN_PANEL_ID,
+  PLUGIN_MARKDOWN_OPTION,
+  SOURCE_OPTION,
+  expectPluginMarkdown,
+  filePanelPicker,
+  installMarkdownPanelPlugin,
+  openMarkdown,
+  storedFilePanelAssociations,
+} from "../support/helpers/markdown-file-panel-plugin";
+import { seedWorkspace } from "../support/helpers/seed-client";
+import { openSettingsSection } from "../support/helpers/settings";
+
+const ASK_EVERY_TIME = "Ask every time";
+
+function markdownRow(page: Page) {
+  return page.getByTestId("file-panel-settings-row-ext:md");
+}
+
+function markdownDropdown(page: Page, value: string) {
+  return markdownRow(page).getByRole("button", { name: `.md: ${value}`, exact: true });
+}
+
+function askAgain(page: Page) {
+  return markdownRow(page).getByRole("button", { name: "Ask again for .md", exact: true });
+}
+
+async function openFilesSettings(page: Page) {
+  await openSettings(page);
+  await openSettingsSection(page, "files");
+  await expect(page.getByTestId("file-panel-settings")).toBeVisible();
+}
+
+async function capture(page: Page, testInfo: TestInfo, name: string) {
+  const file = testInfo.outputPath(`${name}.png`);
+  await page.screenshot({ path: file });
+  await testInfo.attach(name, { path: file, contentType: "image/png" });
+}
+
+async function expectMenuOpen(page: Page) {
+  await expect(page.getByTestId("file-panel-settings-menu")).toHaveCSS("opacity", "1");
+}
+
+test("Settings > Files chooses which panel opens .md and asks again on request", async ({
+  page,
+}, testInfo) => {
+  test.setTimeout(120_000);
+  const workspace = await seedWorkspace({
+    repoPrefix: "file-panel-settings-",
+    repo: { files: [{ path: "notes.md", content: "# notes heading\n" }] },
+  });
+  const plugin = await installMarkdownPanelPlugin();
+  try {
+    await page.setViewportSize({ width: 1280, height: 900 });
+    await gotoWorkspace(page, workspace.workspaceId);
+    await openFilesSettings(page);
+
+    // Nothing remembered: the row asks every time and has nothing to forget.
+    await expect(markdownDropdown(page, ASK_EVERY_TIME)).toBeVisible({ timeout: 30_000 });
+    await expect(askAgain(page)).toBeDisabled();
+    await capture(page, testInfo, "file-panel-settings-wide");
+
+    await markdownDropdown(page, ASK_EVERY_TIME).click();
+    await expect(page.getByRole("menuitem", { name: BUILTIN_MARKDOWN_OPTION })).toBeVisible();
+    await expect(page.getByRole("menuitem", { name: PLUGIN_MARKDOWN_OPTION })).toBeVisible();
+    await expect(page.getByRole("menuitem", { name: SOURCE_OPTION })).toBeVisible();
+    await expectMenuOpen(page);
+    await capture(page, testInfo, "file-panel-settings-wide-menu");
+    await page.getByRole("menuitem", { name: PLUGIN_MARKDOWN_OPTION }).click();
+    await expect(markdownDropdown(page, PLUGIN_MARKDOWN_OPTION)).toBeVisible();
+    await expect
+      .poll(() => storedFilePanelAssociations(page))
+      .toEqual({
+        "ext:md": MARKDOWN_PANEL_ID,
+      });
+    await capture(page, testInfo, "file-panel-settings-wide-chosen");
+
+    // The next open uses the plugin without asking.
+    await gotoWorkspace(page, workspace.workspaceId);
+    await openFileExplorer(page);
+    await openMarkdown(page, "notes.md");
+    await expectPluginMarkdown(page, "notes.md");
+    await expect(filePanelPicker(page)).toBeHidden();
+
+    await page.setViewportSize({ width: 390, height: 844 });
+    await page.goto("/settings/files");
+    await expect(markdownDropdown(page, PLUGIN_MARKDOWN_OPTION)).toBeVisible({ timeout: 30_000 });
+    await expect(askAgain(page)).toBeInViewport({ ratio: 1 });
+    await capture(page, testInfo, "file-panel-settings-compact");
+    await markdownDropdown(page, PLUGIN_MARKDOWN_OPTION).click();
+    await expect(page.getByRole("menuitem", { name: SOURCE_OPTION })).toBeVisible();
+    await expectMenuOpen(page);
+    await capture(page, testInfo, "file-panel-settings-compact-menu");
+    await page.keyboard.press("Escape");
+    await expect(page.getByRole("menuitem", { name: SOURCE_OPTION })).toBeHidden();
+
+    // Ask again forgets the choice; the next open asks.
+    await askAgain(page).click();
+    await expect(markdownDropdown(page, ASK_EVERY_TIME)).toBeVisible();
+    await expect.poll(() => storedFilePanelAssociations(page)).toEqual({});
+    await page.setViewportSize({ width: 1280, height: 900 });
+    await gotoWorkspace(page, workspace.workspaceId);
+    await expect(filePanelPicker(page)).toBeVisible({ timeout: 30_000 });
+  } finally {
+    await plugin.uninstall();
+    await workspace.cleanup();
+  }
+});
+
+test("Settings > Files explains where file panels come from when no plugin adds one", async ({
+  page,
+}, testInfo) => {
+  await page.setViewportSize({ width: 1280, height: 900 });
+  await page.goto("/settings/files");
+  const empty = page.getByTestId("file-panel-settings-empty");
+  await expect(empty).toHaveText("File panels appear here when a plugin adds one", {
+    timeout: 30_000,
+  });
+  await capture(page, testInfo, "file-panel-settings-empty-wide");
+  await page.setViewportSize({ width: 390, height: 844 });
+  await expect(empty).toBeVisible();
+  await capture(page, testInfo, "file-panel-settings-empty-compact");
+});
+
+test("Settings > Files offers Source in place of a panel no host has, and forgets it", async ({
+  page,
+}) => {
+  await page.addInitScript(() => {
+    localStorage.setItem(
+      "@paseo:app-settings",
+      JSON.stringify({ filePanelAssociations: { "ext:pdf": "plugin:none/none" } }),
+    );
+  });
+  await page.goto("/settings/files");
+  const row = page.getByTestId("file-panel-settings-row-ext:pdf");
+  const dropdown = row.getByRole("button", { name: ".pdf: Not on a connected host" });
+  await expect(dropdown).toBeEnabled({ timeout: 30_000 });
+  await dropdown.click();
+  await expect(page.getByRole("menuitem", { name: SOURCE_OPTION })).toBeVisible();
+  await page.keyboard.press("Escape");
+  await expect(page.getByRole("menuitem", { name: SOURCE_OPTION })).toBeHidden();
+  await row.getByRole("button", { name: "Ask again for .pdf", exact: true }).click();
+  await expect(page.getByTestId("file-panel-settings-empty")).toBeVisible();
+});

packages/app/e2e/browser/plugin-file-panels.spec.ts

@@ -0,0 +1,232 @@
+import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import path from "node:path";
+import { expect, test, type Page } from "../support/fixtures";
+import { installDaemonWebSocketGate } from "../support/helpers/daemon-websocket-gate";
+import { pluginRequirements } from "../support/helpers/plugin-fixture";
+import { connectNewWorkspaceDaemonClient } from "../support/helpers/new-workspace";
+import { seedWorkspace } from "../support/helpers/seed-client";
+import { gotoWorkspace } from "../support/helpers/launcher";
+import {
+  openFileExplorer,
+  openFileFromExplorer,
+  expectFileTabOpen,
+} from "../support/helpers/file-explorer";
+
+const PLUGIN_ID = "file-panel-e2e";
+const PDF = Buffer.from("%PDF-1.4\n%\x00\xff\n1 0 obj<</Type/Catalog>>endobj\n%%EOF", "binary");
+const SOURCE = `import React, { useEffect, useState } from "react";
+import { Text, View, Pressable } from "react-native";
+import {
+  PluginFileConflictError,
+  useFileBytes,
+  useFileUrl,
+  usePaseo,
+  useWorkspace,
+} from "@getpaseo/plugin/client";
+import { useQueryClient } from "@tanstack/react-query";
+import { DocumentFrame, Loading } from "@getpaseo/plugin/client/ui";
+function Pdf({ file, workspaceId }) {
+  usePaseo();
+  useQueryClient();
+  const workspace = useWorkspace(workspaceId, value => ({ id: value.id }));
+  const bytes = useFileBytes(file);
+  const url = useFileUrl(file);
+  const [urlBytes, setUrlBytes] = useState(-1);
+  const href = url.status === "ready" ? url.url : null;
+  useEffect(() => {
+    if (href) fetch(href).then(response => response.arrayBuffer()).then(body => setUrlBytes(body.byteLength));
+  }, [href]);
+  if (bytes.status !== "ready" || !href) return <Loading />;
+  return <View style={{ flex: 1 }}>
+    <Text>PDF plugin: {file.name}</Text>
+    <Text>Path {file.path}</Text>
+    <Text>Bytes {bytes.bytes.length}; URL bytes {urlBytes}</Text>
+    <Text>Workspace {workspace?.id}</Text>
+    <DocumentFrame url={href} testID="plugin-pdf-frame" />
+  </View>;
+}
+// Reads once and writes on demand, so a change on disk since that read rejects the write.
+function Markdown({ file, tab }) {
+  const [text, setText] = useState(null);
+  const [status, setStatus] = useState("");
+  useEffect(() => { file.readText().then(setText); }, [file]);
+  const save = (next) => {
+    tab.setModified(true);
+    file.writeText(next).then(
+      () => { tab.setModified(false); setText(next); },
+      (error) => setStatus(error instanceof PluginFileConflictError ? "Write rejected: changed on disk" : String(error)),
+    );
+  };
+  if (text === null) return <Loading />;
+  return <View>
+    <Text>Plugin Markdown: {text}</Text>
+    <Pressable accessibilityRole="button" onPress={() => save("# Saved by plugin\\n")}>
+      <Text>Edit Markdown through plugin</Text>
+    </Pressable>
+    <Text>{status}</Text>
+  </View>;
+}
+export default function contribute(client) {
+  client.addFilePanel({ id: "pdf", title: "PDF", icon: "FileText",
+    files: { extensions: ["pdf", "txt"] }, Component: Pdf });
+  client.addFilePanel({ id: "markdown", title: "Plugin Markdown", icon: "FileText",
+    files: { extensions: ["md"] }, Component: Markdown });
+  return () => {};
+}`;
+
+async function openWorkspaceFile(page: Page, name: string) {
+  await openFileFromExplorer(page, name);
+  await expectFileTabOpen(page, name);
+}
+async function associateMarkdownWithPlugin(page: Page) {
+  await page.evaluate(() => {
+    const key = "@paseo:app-settings";
+    const settings = JSON.parse(localStorage.getItem(key) ?? "{}");
+    settings.filePanelAssociations = { "ext:md": "plugin:file-panel-e2e/markdown" };
+    localStorage.setItem(key, JSON.stringify(settings));
+  });
+  await page.reload();
+}
+async function editMarkdownThroughPlugin(page: Page) {
+  await page.getByRole("button", { name: "Edit Markdown through plugin", exact: true }).click();
+}
+async function selectSource(page: Page) {
+  await page
+    .getByTestId("file-panel-switcher")
+    .filter({ visible: true })
+    .getByRole("button", { name: "Source", exact: true })
+    .click();
+}
+
+test("directory plugins render PDF bytes and write Markdown through the file handle", async ({
+  page,
+}, testInfo) => {
+  test.setTimeout(120_000);
+  const directory = await mkdtemp(path.join(tmpdir(), "paseo-file-panels-plugin-"));
+  const workspace = await seedWorkspace({
+    repoPrefix: "file-panels-",
+    repo: {
+      files: [
+        { path: "notes.md", content: "# Built-in Markdown\n" },
+        { path: "bytes.txt", content: "Bytes panel text document" },
+      ],
+    },
+  });
+  const client = await connectNewWorkspaceDaemonClient({ ownProjects: false });
+  const previousConfig = await client.getDaemonConfig();
+  await writeFile(path.join(workspace.repoPath, "report.pdf"), PDF);
+  await writeFile(
+    path.join(directory, "paseo-plugin.json"),
+    JSON.stringify({ id: PLUGIN_ID, requirements: pluginRequirements }),
+  );
+  await writeFile(path.join(directory, "index.client.tsx"), SOURCE);
+  try {
+    await client.patchDaemonConfig({ pluginsEnabled: true });
+    await client.installDirectoryPlugin(directory);
+    await page.setViewportSize({ width: 1280, height: 900 });
+    const gate = await installDaemonWebSocketGate(page);
+    await gotoWorkspace(page, workspace.workspaceId);
+    await openFileExplorer(page);
+    await openWorkspaceFile(page, "report.pdf");
+    await expect(page.getByText("PDF plugin: report.pdf", { exact: true })).toBeVisible();
+    await expect(
+      page.getByText(`Bytes ${PDF.length}; URL bytes ${PDF.length}`, { exact: true }),
+    ).toBeVisible();
+    await expect(
+      page.getByText(`Workspace ${workspace.workspaceId}`, { exact: true }),
+    ).toBeVisible();
+    await expect(page.getByTitle("Document preview", { exact: true })).toHaveAttribute(
+      "src",
+      /^blob:/,
+    );
+    await expect(
+      page.getByText(`Path ${path.join(workspace.repoPath, "report.pdf")}`, { exact: true }),
+    ).toBeVisible();
+    const pdfScreenshot = testInfo.outputPath("plugin-pdf-web.png");
+    await page.screenshot({ path: pdfScreenshot });
+    await testInfo.attach("plugin-pdf-web", { path: pdfScreenshot, contentType: "image/png" });
+
+    // A plugin panel claiming a text file competes with Source, so Paseo asks over the plugin.
+    await openWorkspaceFile(page, "bytes.txt");
+    await expect(page.getByText("Open .txt files with", { exact: true })).toBeVisible();
+    await page.keyboard.press("Escape");
+    await expect(page.getByText("Open .txt files with", { exact: true })).toBeHidden();
+    await expect(page.getByText("PDF plugin: bytes.txt", { exact: true })).toBeVisible();
+    await expect(page.getByTitle("Document preview", { exact: true })).toBeVisible();
+    await expect(page.getByTitle("Document preview", { exact: true })).toHaveAttribute(
+      "sandbox",
+      "",
+    );
+    await expect(
+      page
+        .frameLocator('[title="Document preview"]')
+        .getByText("Bytes panel text document", { exact: true }),
+    ).toBeVisible();
+
+    await openWorkspaceFile(page, "notes.md");
+    await expect(page.getByText("Open .md files with", { exact: true })).toBeVisible();
+    await page.keyboard.press("Escape");
+    await expect(page.getByText("Open .md files with", { exact: true })).toBeHidden();
+    await expect(
+      page.getByRole("heading", { name: "Built-in Markdown", exact: true }),
+    ).toBeVisible();
+    await expect(page.getByRole("button", { name: "Edit Markdown through plugin" })).toHaveCount(0);
+    await associateMarkdownWithPlugin(page);
+    await expect(
+      page.getByText("Plugin Markdown: # Built-in Markdown", { exact: true }),
+    ).toBeVisible();
+    gate.holdNextClientRequest("fs.file.write.request");
+    await editMarkdownThroughPlugin(page);
+    await gate.waitForHeldClientRequest();
+    await expect(page.getByTestId("workspace-tab-modified-file_notes.md")).toBeVisible();
+    gate.releaseHeldClientRequest();
+    await expect(
+      page.getByText("Plugin Markdown: # Saved by plugin", { exact: true }),
+    ).toBeVisible();
+    await expect
+      .poll(() => readFile(path.join(workspace.repoPath, "notes.md"), "utf8"))
+      .toBe("# Saved by plugin\n");
+    await expect(page.getByTestId("workspace-tab-modified-file_notes.md")).toBeHidden();
+
+    // The disk changed since the plugin's last read or write: the write is rejected, not applied.
+    await writeFile(path.join(workspace.repoPath, "notes.md"), "# Changed outside\n");
+    await editMarkdownThroughPlugin(page);
+    await expect(page.getByText("Write rejected: changed on disk", { exact: true })).toBeVisible();
+    expect(await readFile(path.join(workspace.repoPath, "notes.md"), "utf8")).toBe(
+      "# Changed outside\n",
+    );
+    await expect(page.getByTestId("workspace-tab-modified-file_notes.md")).toBeVisible();
+    let closePrompt = "";
+    page.once("dialog", async (dialog) => {
+      closePrompt = dialog.message();
+      await dialog.dismiss();
+    });
+    await page
+      .getByTestId("workspace-tab-file_notes.md")
+      .filter({ visible: true })
+      .first()
+      .click({ button: "right" });
+    await page.getByRole("menuitem", { name: "Close", exact: true }).click();
+    await expect.poll(() => closePrompt).toContain("discard");
+
+    await selectSource(page);
+    await expect(
+      page.getByTestId("file-source-editor").filter({ visible: true }).locator(".cm-content"),
+    ).toHaveText("# Changed outside");
+    const markdownScreenshot = testInfo.outputPath("plugin-markdown-source-web.png");
+    await page.screenshot({ path: markdownScreenshot });
+    await testInfo.attach("plugin-markdown-source-web", {
+      path: markdownScreenshot,
+      contentType: "image/png",
+    });
+  } finally {
+    await client.removePlugin(PLUGIN_ID);
+    await client.patchDaemonConfig({
+      pluginsEnabled: previousConfig.config.pluginsEnabled ?? false,
+    });
+    await client.close();
+    await workspace.cleanup();
+    await rm(directory, { recursive: true, force: true });
+  }
+});

packages/app/e2e/browser/plugin-host-ui.spec.ts

@@ -1,3 +1,4 @@
+import { verifyPluginTranslations } from "../support/helpers/plugin-translations";
 import { pluginRequirements } from "../support/helpers/plugin-fixture";
 import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
@@ -9,7 +10,7 @@ import { connectNewWorkspaceDaemonClient } from "../support/helpers/new-workspac
 const PLUGIN_ID = "plugin-host-ui-e2e";
 
 const PLUGIN_SOURCE = `import { usePaseo } from "@getpaseo/plugin/client";
-import { Icon, Modal, useToast } from "@getpaseo/plugin/client/react-native";
+import { Icon, Modal, useToast } from "@getpaseo/plugin/client/ui";
 import { useQueryClient } from "@tanstack/react-query";
 import React, { useState } from "react";
 import { Pressable, Text, View } from "react-native";
@@ -166,3 +167,10 @@ async function playPluginAudio(page: Page, button: string, result: string) {
   await page.getByRole("button", { name: button, exact: true }).click();
   await expect(page.getByText(result, { exact: true })).toBeVisible();
 }
+
+test("plugin content and host labels follow app language without losing an open draft", async ({
+  page,
+}, info) => {
+  test.setTimeout(180_000);
+  await verifyPluginTranslations(page, info);
+});

packages/app/e2e/browser/plugin-timeline.spec.ts

@@ -1,6 +1,7 @@
 import { test } from "../support/fixtures";
 import {
   withTimelinePlugin,
+  viewInlineThinkingExample,
   requestPluginTimeline,
   interactWithStreamingCard,
   expectWholeCompletedCard,
@@ -33,3 +34,9 @@ test("Overview preserves both consecutive tool plugin cards", async ({ page }, i
     await expectBothConsecutiveTools(page);
   });
 });
+
+test("inline-thinking example renders a streamed thought through host UI", async ({
+  page,
+}, info) => {
+  await viewInlineThinkingExample(page, info);
+});

packages/app/e2e/browser/plugin-workspace-panels.spec.ts

@@ -36,7 +36,7 @@ function pluginClientSource(input: {
 }): string {
   return `import React, { useRef } from "react";
 import { Pressable, Text, View } from "react-native";
-import { Icon } from "@getpaseo/plugin/client/react-native";
+import { Icon } from "@getpaseo/plugin/client/ui";
 import { useAgent, useWorkspace, openExternalUrl } from "@getpaseo/plugin/client";
 import { ExternalLink } from "@getpaseo/plugin/client/ui";
 import { recordComposerOpen } from "./shared/rpc";

packages/app/e2e/browser/sidebar-nav-settings.spec.ts

@@ -1,4 +1,5 @@
 import { expect, test } from "../support/fixtures";
+import type { Page } from "@playwright/test";
 import { openAddProjectFlow, addProjectFlow } from "../support/helpers/add-project-flow";
 import { installUsageReportsFixture } from "../support/helpers/usage-reports";
 import {
@@ -31,6 +32,28 @@ import {
   setSidebarNavItemVisible,
 } from "../support/helpers/sidebar-nav-settings";
 
+async function showDeveloperToast(page: Page): Promise<void> {
+  await page.evaluate(() => {
+    document.getElementById("error-toast")?.remove();
+    const toast = document.createElement("div");
+    toast.id = "error-toast";
+    toast.style.cssText = "position:fixed;inset:0;z-index:2147483647;background:white";
+    // Expo renders its unnamed dismiss button in an open shadow root.
+    const button = document.createElement("button");
+    button.style.cssText = "width:24px;height:24px";
+    button.addEventListener("click", () => toast.remove());
+    toast.attachShadow({ mode: "open" }).appendChild(button);
+    document.body.appendChild(toast);
+  });
+}
+
+test("developer toasts leave concurrent sidebar layout checks uninterrupted", async ({ page }) => {
+  await gotoAppShell(page);
+  await showDeveloperToast(page);
+  await expectSidebarOrder(page, ["new-workspace", "history", "search", "schedules"]);
+  await expect(page.locator("#error-toast")).toBeHidden();
+});
+
 test("fixed footer line keeps its five icons, Help and Settings at the end", async ({ page }) => {
   test.setTimeout(120_000);
   await installUsageReportsFixture(page, { lists: [() => claudeAndCodexReports()] });

packages/app/e2e/browser/workspace-scripts-menu-resize.spec.ts

@@ -2,6 +2,7 @@ import { test, expect } from "../support/fixtures";
 import { createTempGitRepo } from "../support/helpers/workspace";
 import {
   connectWorkspaceSetupClient,
+  setupCommandOutput,
   createWorkspaceThroughDaemon,
   openWorkspaceScriptsMenu,
   seedProjectForWorkspaceSetup,
@@ -33,7 +34,9 @@ test("scripts menu resizes when a service row grows after launch", async ({ page
     await seedProjectForWorkspaceSetup(client, repo.path);
     const completed = waitForWorkspaceSetupProgress(
       client,
-      (payload) => payload.status === "completed" && payload.detail.log.includes("setup complete"),
+      (payload) =>
+        payload.status === "completed" &&
+        setupCommandOutput(payload.detail).includes("setup complete"),
     );
     const workspace = await createWorkspaceThroughDaemon(client, {
       cwd: repo.path,

packages/app/e2e/browser/workspace-setup-streaming.spec.ts

@@ -18,6 +18,7 @@ import {
 } from "../support/helpers/terminal-perf";
 import {
   connectWorkspaceSetupClient,
+  setupCommandOutput,
   createWorkspaceThroughDaemon,
   expectSetupPanel,
   openHomeWithProject,
@@ -92,7 +93,8 @@ test.describe("Workspace setup streaming", () => {
       const completed = waitForWorkspaceSetupProgress(
         client,
         (payload) =>
-          payload.status === "completed" && payload.detail.log.includes("setup complete"),
+          payload.status === "completed" &&
+          setupCommandOutput(payload.detail).includes("setup complete"),
       );
       const workspace = await createWorkspaceThroughDaemon(client, {
         cwd: repo.path,
@@ -170,16 +172,19 @@ test.describe("Workspace setup streaming", () => {
       await seedProjectForWorkspaceSetup(client, repo.path);
       const initialRunning = waitForWorkspaceSetupProgress(
         client,
-        (payload) => payload.status === "running" && payload.detail.log === "",
+        (payload) => payload.status === "running" && payload.detail.commands.length === 0,
       );
       const runningWithOutput = waitForWorkspaceSetupProgress(
         client,
-        (payload) => payload.status === "running" && payload.detail.log.includes("starting setup"),
+        (payload) =>
+          payload.status === "running" &&
+          setupCommandOutput(payload.detail).includes("starting setup"),
       );
       const completed = waitForWorkspaceSetupProgress(
         client,
         (payload) =>
-          payload.status === "completed" && payload.detail.log.includes("setup complete"),
+          payload.status === "completed" &&
+          setupCommandOutput(payload.detail).includes("setup complete"),
       );
 
       await createWorkspaceThroughDaemon(client, {
@@ -192,8 +197,8 @@ test.describe("Workspace setup streaming", () => {
       const completedPayload = await completed;
 
       expect(initialPayload.detail.log).toBe("");
-      expect(runningPayload.detail.log).toContain("starting setup");
-      expect(completedPayload.detail.log).toContain("setup complete");
+      expect(setupCommandOutput(runningPayload.detail)).toContain("starting setup");
+      expect(setupCommandOutput(completedPayload.detail)).toContain("setup complete");
       expect(completedPayload.error).toBeNull();
     } finally {
       await client.close();
@@ -215,7 +220,9 @@ test.describe("Workspace setup streaming", () => {
       await seedProjectForWorkspaceSetup(client, repo.path);
       const failed = waitForWorkspaceSetupProgress(
         client,
-        (payload) => payload.status === "failed" && payload.detail.log.includes("setup failed"),
+        (payload) =>
+          payload.status === "failed" &&
+          setupCommandOutput(payload.detail).includes("setup failed"),
       );
 
       const workspace = await createWorkspaceThroughDaemon(client, {
@@ -224,8 +231,8 @@ test.describe("Workspace setup streaming", () => {
       });
 
       const failedPayload = await failed;
-      expect(failedPayload.detail.log).toContain("starting setup");
-      expect(failedPayload.detail.log).toContain("setup failed");
+      expect(setupCommandOutput(failedPayload.detail)).toContain("starting setup");
+      expect(setupCommandOutput(failedPayload.detail)).toContain("setup failed");
       expect(failedPayload.error).toMatch(/failed/i);
 
       await openHomeWithProject(page, repo.path);
@@ -331,7 +338,8 @@ test.describe("Workspace setup streaming", () => {
       const completed = waitForWorkspaceSetupProgress(
         client,
         (payload) =>
-          payload.status === "completed" && payload.detail.log.includes("setup complete"),
+          payload.status === "completed" &&
+          setupCommandOutput(payload.detail).includes("setup complete"),
       );
       const workspace = await createWorkspaceThroughDaemon(client, {
         cwd: repo.path,
@@ -377,7 +385,8 @@ test.describe("Workspace setup streaming", () => {
       const completed = waitForWorkspaceSetupProgress(
         client,
         (payload) =>
-          payload.status === "completed" && payload.detail.log.includes("setup complete"),
+          payload.status === "completed" &&
+          setupCommandOutput(payload.detail).includes("setup complete"),
       );
 
       const result = await client.createPaseoWorktree({

packages/app/e2e/support/developer-ui.mjs

@@ -1,10 +1,15 @@
+const HIDE_DEVELOPER_TOASTS = "#error-toast { display: none !important; }";
+
 /** @param {import('@playwright/test').Page} page */
-export async function installDeveloperToastDismissal(page) {
+export async function hideDeveloperToasts(page) {
   // Developer chrome must not cover app actions or move the test's pointer/focus.
-  // Console errors remain in the runner's logs.
-  const dismiss = page.locator("#error-toast").getByRole("button", { name: "", exact: true });
-  await page.addLocatorHandler(dismiss, () => dismiss.dispatchEvent("click"), {
-    // A new logged error can replace the toast before the old one disappears.
-    noWaitAfter: true,
-  });
+  // Console errors remain in the runner's logs. Hiding the toast, instead of clicking it away,
+  // leaves no race with a toast that closes or is replaced between matching and clicking.
+  await page.addInitScript((css) => {
+    const style = document.createElement("style");
+    style.textContent = css;
+    document.addEventListener("DOMContentLoaded", () => document.head.append(style));
+  }, HIDE_DEVELOPER_TOASTS);
+  // A page attached after it loaded (Electron over CDP) runs no init script until it navigates.
+  await page.addStyleTag({ content: HIDE_DEVELOPER_TOASTS });
 }

packages/app/e2e/support/fixtures.ts

@@ -1,5 +1,5 @@
 import { test as base, expect, type Page } from "@playwright/test";
-import { installDeveloperToastDismissal } from "./developer-ui.mjs";
+import { hideDeveloperToasts } from "./developer-ui.mjs";
 import { startOutdatedDaemon, type OutdatedDaemon } from "./helpers/daemon-update";
 import { startE2EWorker } from "./helpers/e2e-worker";
 import { getE2EDaemonPort } from "./helpers/daemon-port";
@@ -131,7 +131,7 @@ const test = daemonTest.extend<{
         await ws.close({ code: 1008, reason: "Blocked connection to localhost:6767 during e2e." });
       });
 
-      await installDeveloperToastDismissal(page);
+      await hideDeveloperToasts(page);
 
       const entries: string[] = [];
 

packages/app/e2e/support/helpers/markdown-file-panel-plugin.ts

@@ -0,0 +1,77 @@
+import { mkdtemp, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import path from "node:path";
+import { expect, type Page } from "@playwright/test";
+import { pluginRequirements } from "./plugin-fixture";
+import { connectNewWorkspaceDaemonClient } from "./new-workspace";
+import { expectFileTabOpen, openFileFromExplorer } from "./file-explorer";
+
+/** A directory plugin whose "Rich Markdown" file panel claims `.md`, next to the built-in. */
+export const MARKDOWN_PANEL_PLUGIN_ID = "file-panel-picker-e2e";
+export const MARKDOWN_PANEL_ID = `plugin:${MARKDOWN_PANEL_PLUGIN_ID}/rich-markdown`;
+export const BUILTIN_MARKDOWN_OPTION = "Markdown — Paseo";
+export const PLUGIN_MARKDOWN_OPTION = `Rich Markdown — ${MARKDOWN_PANEL_PLUGIN_ID}`;
+export const SOURCE_OPTION = "Source — Paseo";
+
+const SOURCE = `import React from "react";
+import { Text, View } from "react-native";
+function RichMarkdown({ file }) {
+  return <View><Text>Rich Markdown plugin: {file.name}</Text></View>;
+}
+export default function contribute(client) {
+  client.addFilePanel({ id: "rich-markdown", title: "Rich Markdown", icon: "FileType",
+    files: { extensions: ["md"] }, Component: RichMarkdown });
+  return () => {};
+}`;
+
+/** Enables plugins on the test daemon and installs the plugin; `uninstall` restores both. */
+export async function installMarkdownPanelPlugin(): Promise<{ uninstall(): Promise<void> }> {
+  const directory = await mkdtemp(path.join(tmpdir(), "paseo-markdown-file-panel-"));
+  const client = await connectNewWorkspaceDaemonClient({ ownProjects: false });
+  const previousConfig = await client.getDaemonConfig();
+  const uninstall = async () => {
+    await client.removePlugin(MARKDOWN_PANEL_PLUGIN_ID);
+    await client.patchDaemonConfig({
+      pluginsEnabled: previousConfig.config.pluginsEnabled ?? false,
+    });
+    await client.close();
+    await rm(directory, { recursive: true, force: true });
+  };
+  try {
+    await writeFile(
+      path.join(directory, "paseo-plugin.json"),
+      JSON.stringify({ id: MARKDOWN_PANEL_PLUGIN_ID, requirements: pluginRequirements }),
+    );
+    await writeFile(path.join(directory, "index.client.tsx"), SOURCE);
+    await client.patchDaemonConfig({ pluginsEnabled: true });
+    await client.installDirectoryPlugin(directory);
+  } catch (error) {
+    await uninstall();
+    throw error;
+  }
+  return { uninstall };
+}
+
+export function filePanelPicker(page: Page) {
+  return page.getByText("Open .md files with", { exact: true });
+}
+
+export async function openMarkdown(page: Page, name: string): Promise<void> {
+  await openFileFromExplorer(page, name);
+  await expectFileTabOpen(page, name);
+}
+
+export async function expectBuiltinMarkdown(page: Page, heading: string): Promise<void> {
+  await expect(page.getByRole("heading", { name: heading, exact: true })).toBeVisible();
+}
+
+export async function expectPluginMarkdown(page: Page, name: string): Promise<void> {
+  await expect(page.getByText(`Rich Markdown plugin: ${name}`, { exact: true })).toBeVisible();
+}
+
+export async function storedFilePanelAssociations(page: Page): Promise<unknown> {
+  return page.evaluate(() => {
+    const settings = JSON.parse(localStorage.getItem("@paseo:app-settings") ?? "{}");
+    return settings.filePanelAssociations ?? {};
+  });
+}

packages/app/e2e/support/helpers/plugin-timeline.ts

@@ -2,7 +2,7 @@ import { mkdtemp, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import path from "node:path";
 import { expect, type Page, type TestInfo } from "@playwright/test";
-import { pluginRequirements } from "./plugin-fixture";
+import { copyPluginExample, pluginRequirements } from "./plugin-fixture";
 import { connectNewWorkspaceDaemonClient } from "./new-workspace";
 import { openAgentRoute, seedMockAgentWorkspace, type MockAgentWorkspace } from "./mock-agent";
 
@@ -274,3 +274,40 @@ export async function withPopoverTimelinePlugin(run: () => Promise<void>): Promi
     run,
   });
 }
+
+const THOUGHT =
+  "Need to find the scroll container, the layout effect that watches for new messages, and any gesture handler that might fight with programmatic scrolling. Probably a ref on the FlatList plus a near-bottom threshold.";
+
+/** Exercises the maintained inline-thinking renderer against real streamed reasoning. */
+export async function viewInlineThinkingExample(page: Page, info: TestInfo): Promise<void> {
+  info.setTimeout(120_000);
+  const example = await copyPluginExample("inline-thinking");
+  const client = await connectNewWorkspaceDaemonClient({ ownProjects: false });
+  const previous = await client.getDaemonConfig();
+  const agent = await seedMockAgentWorkspace({
+    repoPrefix: "inline-thinking-",
+    title: "Inline thinking example",
+    model: "one-minute-stream",
+  });
+  try {
+    await client.patchDaemonConfig({ pluginsEnabled: true });
+    await client.installDirectoryPlugin(example.directory);
+    await openAgentRoute(page, agent);
+    await expect(page.getByRole("textbox", { name: "Message agent..." }).first()).toBeVisible();
+    await requestPluginTimeline(agent);
+    const thought = page.getByText(/^Need to find the scroll container/);
+    await expect(thought).toBeVisible({ timeout: 60_000 });
+    await expect(thought).not.toHaveText(THOUGHT);
+    await info.attach("inline-thinking-streaming", {
+      body: await page.screenshot({ path: info.outputPath("inline-thinking-streaming.png") }),
+      contentType: "image/png",
+    });
+    await expect(thought).toHaveText(THOUGHT, { timeout: 30_000 });
+  } finally {
+    await client.removePlugin("inline-thinking");
+    await client.patchDaemonConfig({ pluginsEnabled: previous.config.pluginsEnabled ?? false });
+    await client.close();
+    await agent.cleanup();
+    await example.cleanup();
+  }
+}

packages/app/e2e/support/helpers/plugin-translations.ts

@@ -0,0 +1,164 @@
+import { hideDeveloperToasts } from "../developer-ui.mjs";
+import { seedWorkspace } from "./seed-client";
+import { buildAgentRoute } from "./mock-agent";
+import { openCommandCenter } from "./command-center";
+import type { TestInfo, BrowserContext } from "@playwright/test";
+import { expect, type Page } from "../fixtures";
+import { gotoAppShell, openSettings } from "./app";
+import { connectNewWorkspaceDaemonClient } from "./new-workspace";
+import { copyPluginExample } from "./plugin-fixture";
+
+async function chooseChinese(page: Page) {
+  await openSettings(page);
+  await page.getByRole("button", { name: "System", exact: true }).click();
+  await page.getByRole("menuitem", { name: "简体中文 - Simplified Chinese", exact: true }).click();
+  await page.goBack();
+}
+
+async function chooseEnglish(page: Page) {
+  await page.getByTestId("sidebar-settings").click();
+  await page.getByRole("button", { name: "简体中文", exact: true }).click();
+  await page.getByRole("menuitem", { name: "English - 英语", exact: true }).click();
+  await page.goBack();
+}
+
+async function capture(page: Page, info: TestInfo, name: string) {
+  const file = info.outputPath(`${name}.png`);
+  await page.screenshot({ path: file, animations: "disabled" });
+  await info.attach(name, { path: file, contentType: "image/png" });
+}
+
+export async function verifyPluginTranslations(page: Page, info: TestInfo) {
+  const example = await copyPluginExample("translations");
+  const client = await connectNewWorkspaceDaemonClient({ ownProjects: false });
+  const config = await client.getDaemonConfig();
+  const browser = page.context().browser();
+  if (!browser) throw new Error("Translation isolation requires a browser");
+  let secondContext: BrowserContext | undefined;
+  try {
+    await client.patchDaemonConfig({ pluginsEnabled: true });
+    await client.installDirectoryPlugin(example.directory);
+    await page.setViewportSize({ width: 1440, height: 1000 });
+    await gotoAppShell(page);
+    await page.getByRole("button", { name: "Workspace notes", exact: true }).click();
+    await expect(page.getByText("App language: en", { exact: true })).toBeVisible();
+    await page
+      .getByRole("textbox", { name: "Your draft", exact: true })
+      .fill("Remember the language switch");
+    await capture(page, info, "01-english-draft");
+    await page.getByRole("button", { name: "Preview draft", exact: true }).click();
+    await expect(page.getByRole("button", { name: "Close preview", exact: true })).toBeVisible();
+    await capture(page, info, "02-english-preview");
+    await page.getByRole("button", { name: "Close preview", exact: true }).click();
+    secondContext = await browser.newContext({
+      storageState: await page.context().storageState(),
+      viewport: { width: 1440, height: 1000 },
+    });
+    const second = await secondContext.newPage();
+    await hideDeveloperToasts(second);
+    await second.goto(page.url());
+    await expect(second.getByText("App language: en", { exact: true })).toBeVisible();
+    await chooseChinese(second);
+    await expect(second.getByText("应用语言：zh-CN", { exact: true })).toBeVisible();
+    await second
+      .getByRole("textbox", { name: "你的草稿", exact: true })
+      .fill("A separate client draft");
+    await expect(page.getByText("App language: en", { exact: true })).toBeVisible();
+    await expect(page.getByTestId("plugin-surface-title")).toHaveText("Workspace notes");
+    await capture(second, info, "03-independent-chinese-client");
+    await chooseChinese(page);
+    await expect(page.getByRole("textbox", { name: "你的草稿", exact: true })).toHaveValue(
+      "Remember the language switch",
+    );
+    await expect(page.getByTestId("plugin-surface-title")).toHaveText("工作区笔记");
+    await expect(page.getByText("应用语言：zh-CN", { exact: true })).toBeVisible();
+    await expect(
+      page.getByText("This English-only message demonstrates fallback.", { exact: true }),
+    ).toBeVisible();
+    await capture(page, info, "04-chinese-draft-preserved");
+    await page.getByRole("button", { name: "预览草稿", exact: true }).click();
+    await expect(page.getByText("草稿预览", { exact: true })).toBeVisible();
+    await expect(page.getByRole("button", { name: "关闭预览", exact: true })).toBeVisible();
+    await capture(page, info, "05-chinese-preview");
+    await page.getByRole("button", { name: "关闭预览", exact: true }).click();
+    await chooseEnglish(page);
+    await expect(page.getByRole("textbox", { name: "Your draft", exact: true })).toHaveValue(
+      "Remember the language switch",
+    );
+    await expect(page.getByTestId("plugin-surface-title")).toHaveText("Workspace notes");
+    await expect(second.getByRole("textbox", { name: "你的草稿", exact: true })).toHaveValue(
+      "A separate client draft",
+    );
+    await capture(page, info, "06-return-to-english-draft-preserved");
+    await page.getByRole("button", { name: "Add note", exact: true }).click();
+    await expect(page.getByText("1 note", { exact: true })).toBeVisible();
+    await page.getByRole("textbox", { name: "Your draft", exact: true }).fill("Second note");
+    await page.getByRole("button", { name: "Add note", exact: true }).click();
+    await expect(page.getByText("2 notes", { exact: true })).toBeVisible();
+  } finally {
+    await secondContext?.close().catch(() => undefined);
+    await client.removePlugin("translation-notes").catch(() => undefined);
+    await client.patchDaemonConfig({ pluginsEnabled: config.config.pluginsEnabled });
+    await client.close();
+    await example.cleanup();
+  }
+}
+
+export async function verifyPluginToolTranslations(page: Page, info: TestInfo) {
+  const workspace = await seedWorkspace({
+    repoPrefix: "translation-tools-",
+    title: "Notes translation QA",
+  });
+  const agent = await workspace.client.createAgent({
+    provider: "mock",
+    cwd: workspace.repoPath,
+    workspaceId: workspace.workspaceId,
+    title: "Notes",
+    model: "ten-second-stream",
+    modeId: "load-test",
+  });
+  const client = await connectNewWorkspaceDaemonClient({ ownProjects: false });
+  const config = await client.getDaemonConfig();
+  const example = await copyPluginExample("translations");
+  try {
+    await client.patchDaemonConfig({ pluginsEnabled: true });
+    await client.installDirectoryPlugin(example.directory);
+    await page.setViewportSize({ width: 1440, height: 1000 });
+    await gotoAppShell(page);
+    await page.goto(buildAgentRoute(workspace.workspaceId, agent.id));
+    const commandCenter = await openCommandCenter(page);
+    await commandCenter.getByTestId("command-center-input").fill("Show notes tools");
+    await commandCenter.getByRole("button", { name: "Show notes tools", exact: true }).click();
+    const tools = page
+      .getByRole("toolbar", { name: "Workspace actions", exact: true })
+      .getByRole("button", { name: "Notes tools", exact: true });
+    await tools.hover();
+    await expect(page.getByRole("tooltip")).toContainText("Notes tools");
+    await capture(page, info, "07-english-tooltip");
+    await tools.click();
+    await page.getByRole("menuitem", { name: "Open notes panel", exact: true }).click();
+    await page
+      .getByRole("textbox", { name: "Your draft", exact: true })
+      .fill("A workspace panel draft");
+    await chooseChinese(page);
+    await expect(page.getByRole("textbox", { name: "你的草稿", exact: true })).toHaveValue(
+      "A workspace panel draft",
+    );
+    const translatedTools = page
+      .getByRole("toolbar")
+      .getByRole("button", { name: "笔记工具", exact: true });
+    await translatedTools.hover();
+    await expect(page.getByRole("tooltip")).toContainText("笔记工具");
+    await capture(page, info, "08-chinese-tooltip-and-panel-draft");
+    await translatedTools.click();
+    await expect(page.getByRole("menuitem", { name: "打开笔记面板", exact: true })).toBeVisible();
+    await capture(page, info, "09-chinese-menu");
+    await page.keyboard.press("Escape");
+  } finally {
+    await client.removePlugin("translation-notes").catch(() => undefined);
+    await client.patchDaemonConfig({ pluginsEnabled: config.config.pluginsEnabled });
+    await client.close();
+    await example.cleanup();
+    await workspace.cleanup();
+  }
+}

packages/app/e2e/support/helpers/settings.ts

@@ -24,6 +24,7 @@ const SECTION_LABELS = {
   appearance: "Appearance",
   sidebar: "Sidebar",
   editor: "Editor",
+  files: "Files",
   terminal: "Terminal",
   browser: "Browser",
   shortcuts: "Shortcuts",

packages/app/e2e/support/helpers/workspace-setup.ts

@@ -376,3 +376,7 @@ export function observeSetupPanelTraffic(page: Page) {
     },
   };
 }
+
+export function setupCommandOutput(detail: { commands: Array<{ log: string }> }): string {
+  return detail.commands.map((command) => command.log).join("\n");
+}

packages/app/index.ts

@@ -9,6 +9,8 @@ import "@expo/metro-runtime";
 // oxlint-disable-next-line import/no-unassigned-import -- Preserve Expo's entry side effects.
 import "expo-router/build/fast-refresh";
 import { renderRootComponent } from "expo-router/build/renderRootComponent";
+import { startWatchdog } from "./src/watchdog";
 import { RootApp } from "./src/root-app";
 
+startWatchdog();
 renderRootComponent(RootApp);

packages/app/metro.config.cjs

@@ -5,6 +5,7 @@ const path = require("path");
 const projectRoot = __dirname;
 const appNodeModulesRoot = path.resolve(projectRoot, "node_modules");
 const appSrcRoot = path.resolve(projectRoot, "src");
+const isWatchdogBuild = process.env.PASEO_WATCHDOG_BUILD === "1";
 const isFdroidBuild = process.env.PASEO_FDROID_BUILD === "1";
 const fdroidModuleOverrides = {
   "expo-camera": path.resolve(appSrcRoot, "fdroid/expo-camera.tsx"),
@@ -16,6 +17,7 @@ const customWebPlatform = (process.env.PASEO_WEB_PLATFORM ?? "")
   .toLowerCase();
 
 const config = getDefaultConfig(projectRoot);
+config.cacheVersion = isWatchdogBuild ? "watchdog" : "standard";
 const defaultResolveRequest = config.resolver.resolveRequest ?? resolve;
 
 // Keep app exports deterministic across dev machines and CI. Metro's Watchman
@@ -75,6 +77,14 @@ function resolveWithCustomWebOverlay(context, moduleName, platform) {
 }
 
 config.resolver.resolveRequest = (context, moduleName, platform) => {
+  if (
+    isWatchdogBuild &&
+    platform === "android" &&
+    /[/\\]Renderer[/\\]shims[/\\]/.test(context.originModulePath) &&
+    /implementations\/(ReactFabric|ReactNativeRenderer)-prod$/.test(moduleName)
+  ) {
+    return defaultResolveRequest(context, moduleName.replace(/-prod$/, "-profiling"), platform);
+  }
   if (isFdroidBuild && platform === "android" && fdroidModuleOverrides[moduleName]) {
     return resolveWithCustomWebOverlay(context, fdroidModuleOverrides[moduleName], platform);
   }

packages/app/modules/paseo-diff-prototype/cpp/jni.cpp

@@ -7,6 +7,7 @@
 #include <stdexcept>
 #include <unordered_map>
 #include "include/ports/SkFontMgr_android.h"
+#include "include/ports/SkFontScanner_FreeType.h"
 #include "modules/skunicode/include/SkUnicode.h"
 
 namespace {
@@ -86,7 +87,7 @@ extern "C" JNIEXPORT jdoubleArray JNICALL METHOD(prepareDocument)(
     const auto fontFamily = SkUnicode::convertUtf16ToUtf8(copyString(env, family));
     const double copyMs = elapsed(copyStart);
     const auto layoutStart = Clock::now();
-    paseo::diff::prepare(*document, SkFontMgr_New_Android(nullptr), fontFamily.c_str(), size, job->cancelled);
+    paseo::diff::prepare(*document, SkFontMgr_New_Android(nullptr, SkFontScanner_Make_FreeType()), fontFamily.c_str(), size, job->cancelled);
     const double layoutMs = elapsed(layoutStart);
     {
       std::lock_guard lock(mutex);

packages/app/modules/paseo-diff-prototype/cpp/layout.cpp

@@ -13,6 +13,7 @@
 #include "modules/skparagraph/include/Paragraph.h"
 #include "modules/skparagraph/include/ParagraphBuilder.h"
 #include "modules/skunicode/include/SkUnicode.h"
+#include "modules/skunicode/include/SkUnicode_icu.h"
 
 namespace paseo::diff {
 namespace {
@@ -178,7 +179,7 @@ class Measurer {
     return it->second;
   }
   std::unique_ptr<para::Paragraph> shape(const std::u16string& text) {
-    auto builder = para::ParagraphBuilder::make(style_, fonts_);
+    auto builder = para::ParagraphBuilder::make(style_, fonts_, SkUnicodes::ICU::Make());
     builder->pushStyle(textStyle_);
     const auto utf8 = SkUnicode::convertUtf16ToUtf8(text);
     builder->addText(utf8.c_str(), utf8.size());

packages/app/modules/paseo-native-trace/android/build.gradle

@@ -13,3 +13,7 @@ useDefaultAndroidSdkVersions()
 android {
   namespace "sh.paseo.trace"
 }
+
+dependencies {
+  testImplementation "junit:junit:4.13.2"
+}

packages/app/modules/paseo-native-trace/android/src/main/java/sh/paseo/trace/DiagnosticRecorder.kt

@@ -0,0 +1,77 @@
+package sh.paseo.trace
+
+import android.content.Context
+import android.os.SystemClock
+import android.util.Log
+import org.json.JSONObject
+import java.util.UUID
+import java.util.concurrent.ArrayBlockingQueue
+import java.util.concurrent.Executors
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.atomic.AtomicLong
+
+/** All serialization and storage belongs to the worker, never the JS/UI threads. */
+internal class DiagnosticRecorder(private val context: Context, private val metadata: Map<String, String>) {
+  private data class Event(val name: String, val data: Map<String, String>, val monoMs: Long = SystemClock.elapsedRealtime(), val wallMs: Long = System.currentTimeMillis())
+  private val queue = ArrayBlockingQueue<Event>(2048)
+  private val dropped = AtomicLong()
+  private val worker = Executors.newSingleThreadScheduledExecutor()
+  private val session = UUID.randomUUID().toString()
+  @Volatile private var failed = false
+  private val watchdog = HeartbeatWatchdog(SystemClock.elapsedRealtime(), ::record)
+
+  private val log = RotatingLog(DownloadsLogStorage(context, session), { part ->
+    serialize(Event("file.start", metadata + mapOf("schema" to "1", "part" to "$part")))
+  }, { error ->
+    failed = true
+    queue.clear()
+    Log.e("PaseoDiagnostics", "Diagnostic recording stopped: storage unavailable", error)
+  })
+
+  init {
+    record("session.start", metadata + mapOf("session" to session, "schema" to "1", "heartbeatMs" to "${HeartbeatTiming.intervalMs}", "stallThresholdMs" to "${HeartbeatTiming.overdueMs}"))
+    worker.scheduleWithFixedDelay({ drain() }, 0, HeartbeatTiming.intervalMs, TimeUnit.MILLISECONDS)
+  }
+
+  fun record(name: String, data: Map<String, String>) {
+    if (failed) return
+    // Limit native memory even if an instrumentation caller accidentally supplies large fields.
+    val bounded = data.entries.take(24).associate { it.key.take(80) to it.value.take(256) }
+    if (!queue.offer(Event(name.take(120), bounded))) dropped.incrementAndGet()
+  }
+
+  fun heartbeat() = watchdog.heartbeat(SystemClock.elapsedRealtime())
+  fun active(value: Boolean) = watchdog.active(value, SystemClock.elapsedRealtime())
+
+  private fun drain() {
+    if (failed) return
+    watchdog.check(SystemClock.elapsedRealtime())
+    val lost = dropped.getAndSet(0)
+    if (lost > 0) write(Event("recorder.dropped", mapOf("count" to "$lost")))
+    var remaining = 2048
+    while (remaining-- > 0 && !failed) {
+      val event = queue.poll() ?: break
+      write(event)
+    }
+    log.finishBatch()
+  }
+
+  private fun write(event: Event) = log.write(serialize(event))
+
+  private fun serialize(event: Event): ByteArray = (JSONObject().apply {
+    put("event", event.name)
+    put("session", session)
+    put("wallMs", event.wallMs)
+    put("monoMs", event.monoMs)
+    put("data", JSONObject(event.data))
+  }.toString() + "\n").toByteArray(Charsets.UTF_8)
+
+  fun close() {
+    worker.execute {
+      record("session.end", emptyMap())
+      drain()
+      log.finishBatch()
+    }
+    worker.shutdown()
+  }
+}

packages/app/modules/paseo-native-trace/android/src/main/java/sh/paseo/trace/DownloadsLogStorage.kt

@@ -0,0 +1,36 @@
+package sh.paseo.trace
+
+import android.content.ContentUris
+import android.content.ContentValues
+import android.content.Context
+import android.net.Uri
+import android.provider.MediaStore
+import java.io.OutputStream
+
+internal class DownloadsLogStorage(private val context: Context, private val session: String) : LogStorage {
+  private val resolver = context.contentResolver
+  private val collection = MediaStore.Downloads.EXTERNAL_CONTENT_URI
+  private val directory = "Download/Paseo diagnostics/"
+
+  override fun create(part: Int): String {
+    val values = ContentValues().apply {
+      put(MediaStore.MediaColumns.DISPLAY_NAME, "paseo-diagnostics-${System.currentTimeMillis()}-${session.take(8)}-$part.jsonl")
+      put(MediaStore.MediaColumns.MIME_TYPE, "application/x-ndjson")
+      put(MediaStore.MediaColumns.RELATIVE_PATH, directory)
+    }
+    return checkNotNull(resolver.insert(collection, values)).toString()
+  }
+
+  override fun append(id: String): OutputStream =
+    checkNotNull(resolver.openOutputStream(Uri.parse(id), "wa")).buffered(64 * 1024)
+
+  override fun newest(): List<String> = buildList {
+    resolver.query(collection, arrayOf(MediaStore.MediaColumns._ID),
+      "${MediaStore.MediaColumns.RELATIVE_PATH} = ? AND ${MediaStore.MediaColumns.OWNER_PACKAGE_NAME} = ?",
+      arrayOf(directory, context.packageName), "${MediaStore.MediaColumns._ID} DESC")?.use { cursor ->
+      while (cursor.moveToNext()) add(ContentUris.withAppendedId(collection, cursor.getLong(0)).toString())
+    }
+  }
+
+  override fun delete(id: String) { resolver.delete(Uri.parse(id), null, null) }
+}

packages/app/modules/paseo-native-trace/android/src/main/java/sh/paseo/trace/HeartbeatWatchdog.kt

@@ -0,0 +1,38 @@
+package sh.paseo.trace
+
+internal object HeartbeatTiming {
+  const val intervalMs = 250L
+  const val overdueMs = 500L
+  const val gapMs = intervalMs + overdueMs
+}
+
+/** Monotonic time is supplied by the owner, so suspension and recovery are deterministic. */
+internal class HeartbeatWatchdog(startMs: Long, private val emit: (String, Map<String, String>) -> Unit) {
+  private var foreground = true
+  private var lastHeartbeat = startMs
+  private var overdue = false
+
+  @Synchronized fun heartbeat(now: Long) {
+    if (foreground && now - lastHeartbeat > HeartbeatTiming.gapMs) {
+      emit("js.stall.recovered", mapOf("heartbeatGapMs" to "${now - lastHeartbeat}", "overdueMs" to "${now - lastHeartbeat - HeartbeatTiming.intervalMs}"))
+    }
+    lastHeartbeat = now
+    overdue = false
+  }
+
+  @Synchronized fun active(value: Boolean, now: Long) {
+    if (foreground == value) return
+    emit("app.lifecycle", mapOf("state" to if (value) "foreground" else "background", "stallOpen" to "$overdue"))
+    foreground = value
+    lastHeartbeat = now
+    overdue = false
+  }
+
+  @Synchronized fun check(now: Long) {
+    val gap = now - lastHeartbeat
+    if (foreground && gap > HeartbeatTiming.gapMs && !overdue) {
+      emit("js.stall.started", mapOf("heartbeatGapMs" to "$gap", "lastHeartbeatMonoMs" to "$lastHeartbeat"))
+      overdue = true
+    }
+  }
+}

packages/app/modules/paseo-native-trace/android/src/main/java/sh/paseo/trace/PaseoNativeTraceModule.kt

@@ -5,9 +5,23 @@ import expo.modules.kotlin.modules.Module
 import expo.modules.kotlin.modules.ModuleDefinition
 
 class PaseoNativeTraceModule : Module() {
+  private var recorder: DiagnosticRecorder? = null
+
   override fun definition() = ModuleDefinition {
     Name("PaseoNativeTrace")
 
+    Function("startRecorder") { metadata: Map<String, String> ->
+      if (recorder == null) {
+        appContext.reactContext?.applicationContext?.let { recorder = DiagnosticRecorder(it, metadata) }
+      }
+      HeartbeatTiming.intervalMs
+    }
+    Function("record") { name: String, data: Map<String, String> -> recorder?.record(name, data) }
+    Function("heartbeat") { recorder?.heartbeat() }
+    OnActivityEntersForeground { recorder?.active(true) }
+    OnActivityEntersBackground { recorder?.active(false) }
+    OnDestroy { recorder?.close(); recorder = null }
+
     Function("beginSection") { name: String ->
       Trace.beginSection(name.take(127))
     }

packages/app/modules/paseo-native-trace/android/src/main/java/sh/paseo/trace/RotatingLog.kt

@@ -0,0 +1,61 @@
+package sh.paseo.trace
+
+import java.io.OutputStream
+
+/** Storage supplies installation-owned files, newest first. */
+internal interface LogStorage {
+  fun create(part: Int): String
+  fun append(id: String): OutputStream
+  fun newest(): List<String>
+  fun delete(id: String)
+}
+
+/** Owns file identity, bounded retention and the terminal storage-failure state. */
+internal class RotatingLog(
+  private val storage: LogStorage,
+  private val header: (Int) -> ByteArray,
+  private val onFailure: (Exception) -> Unit,
+  private val maxBytes: Int = 5 * 1024 * 1024,
+) {
+  private var current: String? = null
+  private var output: OutputStream? = null
+  private var size = 0
+  private var part = 0
+  var failed = false
+    private set
+
+  fun write(bytes: ByteArray) = attempt {
+    if (current == null || size + bytes.size > maxBytes) {
+      finishBatch()
+      if (failed) return@attempt
+      val nextPart = part++
+      current = storage.create(nextPart)
+      output = storage.append(checkNotNull(current))
+      val first = header(nextPart)
+      output!!.write(first)
+      size = first.size
+      storage.newest().drop(8).forEach(storage::delete)
+    }
+    if (output == null) output = storage.append(checkNotNull(current))
+    output!!.write(bytes)
+    size += bytes.size
+  }
+
+  // Closing publishes size and modification time in Android Files.
+  fun finishBatch() = attempt {
+    output?.close()
+    output = null
+  }
+
+  private fun attempt(action: () -> Unit) {
+    if (failed) return
+    try {
+      action()
+    } catch (error: Exception) {
+      failed = true
+      runCatching { output?.close() }
+      output = null
+      onFailure(error)
+    }
+  }
+}

packages/app/modules/paseo-native-trace/android/src/test/java/sh/paseo/trace/HeartbeatWatchdogTest.kt

@@ -0,0 +1,40 @@
+package sh.paseo.trace
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class HeartbeatWatchdogTest {
+  @Test fun recordsOneStartAndRecoveryWithMeasuredGap() {
+    val events = mutableListOf<Pair<String, Map<String, String>>>()
+    val watchdog = HeartbeatWatchdog(0) { name, fields -> events.add(name to fields) }
+    watchdog.heartbeat(250)
+    watchdog.check(1000)
+    assertEquals(emptyList<Pair<String, Map<String, String>>>(), events)
+    watchdog.check(1001)
+    watchdog.check(2000)
+    watchdog.heartbeat(2250)
+    assertEquals(listOf(
+      "js.stall.started" to mapOf("heartbeatGapMs" to "751", "lastHeartbeatMonoMs" to "250"),
+      "js.stall.recovered" to mapOf("heartbeatGapMs" to "2000", "overdueMs" to "1750")
+    ), events)
+  }
+
+  @Test fun backgroundAndResumeDoNotLookLikeStalls() {
+    val events = mutableListOf<String>()
+    val watchdog = HeartbeatWatchdog(0) { name, _ -> events.add(name) }
+    watchdog.active(false, 100)
+    watchdog.check(300000)
+    watchdog.heartbeat(300100)
+    watchdog.active(true, 400000)
+    watchdog.heartbeat(400250)
+    watchdog.check(400500)
+    assertEquals(listOf("app.lifecycle", "app.lifecycle"), events)
+  }
+
+  @Test fun recoveryIsReportedEvenIfNativeSamplingMissedTheGap() {
+    val events = mutableListOf<String>()
+    val watchdog = HeartbeatWatchdog(0) { name, _ -> events.add(name) }
+    watchdog.heartbeat(900)
+    assertEquals(listOf("js.stall.recovered"), events)
+  }
+}

packages/app/modules/paseo-native-trace/android/src/test/java/sh/paseo/trace/RotatingLogTest.kt

@@ -0,0 +1,59 @@
+package sh.paseo.trace
+
+import java.io.ByteArrayOutputStream
+import java.io.IOException
+import java.io.OutputStream
+import org.junit.Assert.*
+import org.junit.Test
+
+class RotatingLogTest {
+  private class MemoryStorage : LogStorage {
+    val files = linkedMapOf<String, ByteArrayOutputStream>()
+    var fail = false
+    var opens = 0
+    override fun create(part: Int): String {
+      val id = "part-$part"
+      files[id] = ByteArrayOutputStream()
+      return id
+    }
+    override fun append(id: String): OutputStream {
+      opens++
+      if (fail) throw IOException("disk full")
+      return files.getValue(id)
+    }
+    override fun newest() = files.keys.reversed()
+    override fun delete(id: String) { files.remove(id) }
+  }
+
+  @Test fun rotatesAtByteLimitAndKeepsEightIncludingCurrent() {
+    val storage = MemoryStorage()
+    val log = RotatingLog(storage, { "header:$it\n".toByteArray() }, { throw it }, 20)
+    repeat(10) { log.write("123456789012".toByteArray()); log.finishBatch() }
+    assertEquals((2..9).map { "part-$it" }, storage.files.keys.toList())
+    for (part in 2..9) assertEquals("header:$part\n123456789012", storage.files.getValue("part-$part").toString("UTF-8"))
+    assertFalse(log.failed)
+  }
+
+  @Test fun reopeningBatchAppendsWithoutRepeatingHeaderAndExactLimitFits() {
+    val storage = MemoryStorage()
+    val log = RotatingLog(storage, { "H".toByteArray() }, { throw it }, 5)
+    log.write("12".toByteArray())
+    log.finishBatch()
+    log.write("34".toByteArray())
+    assertEquals(listOf("part-0"), storage.files.keys.toList())
+    assertEquals("H1234", storage.files.getValue("part-0").toString("UTF-8"))
+    log.write("5".toByteArray())
+    assertEquals("H5", storage.files.getValue("part-1").toString("UTF-8"))
+  }
+
+  @Test fun storageFailureStopsRecordingWithoutRetryStorm() {
+    val storage = MemoryStorage()
+    var failures = 0
+    val log = RotatingLog(storage, { byteArrayOf() }, { failures++ })
+    storage.fail = true
+    repeat(100) { log.write(byteArrayOf(1)); log.finishBatch() }
+    assertTrue(log.failed)
+    assertEquals(1, failures)
+    assertEquals(1, storage.opens)
+  }
+}

packages/app/package.json

@@ -8,12 +8,12 @@
     "start:expo": "cross-env APP_VARIANT=development expo start",
     "reset-project": "node ./scripts/reset-project.js",
     "eas-build-post-install": "npm --prefix ../.. run build:app-deps && npm run build:terminal-webview",
-    "android": "npm run android:development",
-    "android:development": "npm --prefix ../.. run build:client && cross-env APP_VARIANT=development expo prebuild --platform android --clean --non-interactive && cross-env APP_VARIANT=development expo run:android --variant=debug",
+    "android": "npm run dev:android",
+    "android:development": "npm run dev:android",
     "android:production": "npm --prefix ../.. run build:client && cross-env APP_VARIANT=production expo prebuild --platform android --clean --non-interactive && cross-env APP_VARIANT=production expo run:android --variant=release",
     "android:release": "npm run android:production",
     "android:clear": "node -e \"require('node:fs').rmSync('android', { recursive: true, force: true })\"",
-    "ios": "npm --prefix ../.. run build:client && expo run:ios",
+    "ios": "npm run dev:ios",
     "ios:release": "npm --prefix ../.. run build:client && expo run:ios --configuration Release",
     "web": "npm --prefix ../.. run build:client && concurrently --kill-others --names protocol,client,expo --prefix-colors yellow,blue,magenta \"npm --prefix ../.. run watch:protocol\" \"npm --prefix ../.. run watch:client\" \"npm run web:expo\"",
     "web:expo": "expo start --web",
@@ -36,7 +36,12 @@
     "profile:workspace-tabs": "node ./scripts/profile-workspace-tabs.mjs",
     "deploy:web": "npm run build:web && wrangler pages deploy dist --project-name paseo-app --branch main",
     "build:terminal-webview": "node ./scripts/build-terminal-webview-html.mjs",
-    "build:mermaid-runtime": "node ./src/components/markdown/fence/mermaid/build-runtime.mjs"
+    "build:mermaid-runtime": "node ./src/components/markdown/fence/mermaid/build-runtime.mjs",
+    "dev:android": "npm --prefix ../.. run build:client && cross-env APP_VARIANT=development expo prebuild --platform android --clean --non-interactive && cross-env APP_VARIANT=development expo run:android --variant=debug",
+    "dev:ios": "npm --prefix ../.. run build:client && cross-env APP_VARIANT=development expo run:ios",
+    "build:apk": "npm --prefix ../.. run build:apk",
+    "build:apk:arm64": "npm --prefix ../.. run build:apk:arm64",
+    "test:android": "expo prebuild --platform android --no-install && cd android && ./gradlew :paseo-native-trace:testReleaseUnitTest --no-daemon --max-workers=2 -Dorg.gradle.parallel=false"
   },
   "dependencies": {
     "@codemirror/commands": "6.10.4",

packages/app/src/agent-stream/presentation.test.ts

@@ -1,3 +1,4 @@
+import { PluginTranslationRuntime } from "@getpaseo/plugin/client/host";
 import { runPluginClientBundle, type PluginClientRuntime } from "@/plugins/evaluate";
 import { transformTimelineItem, type TimelineItemTransform } from "@/plugins/timeline/model";
 import type { InstalledPlugin } from "@/plugins/types";
@@ -61,6 +62,8 @@ function installProbe(
     serverId: "host-1",
     clientBundle,
     lifetime: new AbortController(),
+    locale: "en",
+    i18n: new PluginTranslationRuntime({ getLocale: () => "en", subscribe: () => () => {} }),
     queryClient: new QueryClient(),
     paseo: {} as InstalledPlugin["paseo"],
     invoke: async () => undefined,

packages/app/src/assistant-file-links/parse.ts

@@ -23,6 +23,8 @@ const INLINE_PAREN_LINE_SUFFIX = /^(.+?)\(([0-9]+)(?:,[0-9]+)?(?:-([0-9]+)(?:,[0
 const INLINE_WORD_LINE_SUFFIX = /^(.+?)\s+lines?\s+([0-9]+)(?:-([0-9]+))?$/i;
 export interface AssistantHrefParseOptions {
   workspaceRoot?: string;
+  /** Authored document links resolve from this directory, independently of the workspace. */
+  relativePathBase?: string;
   /** Authored links identify a file; only inferred text needs filename heuristics. */
   explicitLink?: boolean;
   /**
@@ -281,6 +283,7 @@ export function parseAssistantFileLink(
     workspaceRoot: options.workspaceRoot,
     decodeHref: options.decodeHref,
     explicitLink: options.explicitLink,
+    relativePathBase: options.relativePathBase,
   });
   if (relativeTarget) {
     return relativeTarget;
@@ -395,6 +398,15 @@ function parseWorkspaceRelativeFileLink(
     };
   }
 
+  const documentBase = options.explicitLink && normalizePathInput(options.relativePathBase);
+  if (documentBase) {
+    return {
+      raw: value,
+      path: resolveDocumentRelativePath(parsed.path, documentBase),
+      ...parsed.lines,
+    };
+  }
+
   const workspaceRoot = normalizePathInput(options.workspaceRoot);
   if (!workspaceRoot) {
     return null;
@@ -638,6 +650,24 @@ function isDomainLikePathSegment(segment: string): boolean {
   return /^[A-Za-z0-9-]+(?:\.[A-Za-z0-9-]+)+$/.test(segment);
 }
 
+function resolveDocumentRelativePath(relativePath: string, baseDirectory: string): string {
+  const prefix = baseDirectory.startsWith("/") ? "/" : "";
+  const segments = baseDirectory.split("/").filter(Boolean);
+  for (const segment of relativePath.split("/")) {
+    const last = segments.at(-1) ?? "";
+    if (!segment || segment === ".") continue;
+    if (segment !== "..") {
+      segments.push(segment);
+    } else if (last && last !== "~" && last !== ".." && !/^[A-Za-z]:$/.test(last)) {
+      segments.pop();
+    } else if (!prefix && !/^[A-Za-z]:$/.test(last)) {
+      segments.push("..");
+    }
+  }
+  const resolved = prefix + segments.join("/");
+  return /^[A-Za-z]:$/.test(resolved) ? `${resolved}/` : resolved;
+}
+
 function resolveRelativePathUnderRoot(pathValue: string, workspaceRoot: string): string | null {
   const normalizedPath = normalizePathToken(pathValue);
   if (!normalizedPath || isAbsolutePath(normalizedPath)) {

packages/app/src/assistant-file-links/provider.tsx

@@ -22,6 +22,7 @@ export interface AssistantFileLinkResolverConfig {
   client?: AssistantFileLinkDaemonClient | null;
   serverId?: string;
   workspaceRoot?: string;
+  relativePathBase?: string;
   onOpenWorkspaceFile?: (target: InlinePathTarget, disposition: OpenFileDisposition) => void;
   toast?: ToastApi | null;
 }
@@ -42,6 +43,7 @@ export function AssistantFileLinkResolverProvider({
   client,
   serverId,
   workspaceRoot,
+  relativePathBase,
   onOpenWorkspaceFile,
   toast,
   children,
@@ -50,10 +52,18 @@ export function AssistantFileLinkResolverProvider({
     client,
     serverId,
     workspaceRoot,
+    relativePathBase,
     onOpenWorkspaceFile,
     toast,
   });
-  configRef.current = { client, serverId, workspaceRoot, onOpenWorkspaceFile, toast };
+  configRef.current = {
+    client,
+    serverId,
+    workspaceRoot,
+    relativePathBase,
+    onOpenWorkspaceFile,
+    toast,
+  };
 
   const getDirectorySuggestions = useCallback<GetDirectorySuggestions>(async (input) => {
     const activeClient = configRef.current.client;

packages/app/src/assistant-file-links/resolver.test.ts

@@ -18,6 +18,50 @@ const CONTEXT: AssistantFileLinkContext = {
   workspaceRoot: "/Users/test/project",
 };
 
+it.each([
+  ["guide/details.md", "/repo/docs/guide/details.md"],
+  ["../README.md", "/repo/README.md"],
+  ["guide/details%20page.md", "/repo/docs/guide/details page.md"],
+])("resolves authored href %s from its document directory", (href, expected) => {
+  expect(
+    classifyForResolution({ href }, { workspaceRoot: "/repo", relativePathBase: "/repo/docs" }),
+  ).toMatchObject({ kind: "resolved", value: { kind: "file", target: { path: expected } } });
+});
+
+it.each([
+  ["C:/repo/docs", "../README.md", "C:/repo/README.md"],
+  ["C:/repo/docs", "../../", "C:/"],
+  ["~/.paseo/docs", "../guide.md", "~/.paseo/guide.md"],
+  ["/repo/docs", "/other/file.md", "/other/file.md"],
+  ["/repo/docs", "file:///other/file.md", "/other/file.md"],
+  ["/repo/docs", "guide/details.md#L3", "/repo/docs/guide/details.md"],
+])(
+  "resolves %s with href %s without changing absolute destinations",
+  (relativePathBase, href, expected) => {
+    expect(
+      classifyForResolution({ href }, { workspaceRoot: "/repo", relativePathBase }),
+    ).toMatchObject({
+      kind: "resolved",
+      value: { kind: "file", target: { path: expected } },
+    });
+  },
+);
+
+it("keeps inferred paths and chat links rooted at the workspace", () => {
+  const context = { workspaceRoot: "/repo", relativePathBase: "/repo/docs" };
+  expect(classifyForResolution({ href: "src/file.ts", markup: "linkify" }, context)).toMatchObject({
+    value: { kind: "file", target: { path: "/repo/src/file.ts" } },
+  });
+  expect(
+    classifyForResolution({ href: "guide/details.md" }, { workspaceRoot: "/repo" }),
+  ).toMatchObject({
+    value: { kind: "file", target: { path: "/repo/guide/details.md" } },
+  });
+  expect(classifyForResolution({ href: "https://example.com/docs" }, context)).toMatchObject({
+    value: { kind: "external", url: "https://example.com/docs" },
+  });
+});
+
 it.each(["docs/guides", "docs/guides/", "docs/%E6%8C%87%E5%8D%97"])(
   "resolves an explicit extensionless folder href: %s",
   (href) => {

packages/app/src/assistant-file-links/resolver.ts

@@ -17,6 +17,7 @@ export interface AssistantFileLinkSource {
 
 export interface AssistantFileLinkContext {
   workspaceRoot?: string;
+  relativePathBase?: string;
 }
 
 export interface DirectorySuggestionEntry {
@@ -118,6 +119,7 @@ export function classifyForResolution(
     workspaceRoot: context.workspaceRoot,
     decodeHref: tokenInfo.fromHref,
     explicitLink: source.sourceType !== "inline-code" && !isLinkifiedSource(source),
+    relativePathBase: context.relativePathBase,
   });
   if (!classification) {
     return { kind: "resolved", value: { kind: "ignored" } };

packages/app/src/assistant-file-links/use-file-link.ts

@@ -15,6 +15,7 @@ import {
   fetchDaemonResolution,
   type AssistantFileLinkResolution,
   type AssistantFileLinkSource,
+  type AssistantFileLinkContext,
 } from "./resolver";
 
 export interface UseFileLinkResult {
@@ -54,13 +55,15 @@ export function useFileLink(source: AssistantFileLinkSource): UseFileLinkResult
   const stableSource = useStableSource(source);
   const activeConfig = context.configRef.current;
   const workspaceRoot = activeConfig.workspaceRoot;
+  const relativePathBase = activeConfig.relativePathBase;
   const serverId = activeConfig.serverId;
   const resolution = useMemo(
     () =>
       classifyForResolution(stableSource, {
         workspaceRoot,
+        relativePathBase,
       }),
-    [stableSource, workspaceRoot],
+    [stableSource, workspaceRoot, relativePathBase],
   );
   const queryKey = useMemo(
     () =>
@@ -154,12 +157,12 @@ export function useAssistantFileLinkActions(): AssistantFileLinkActions {
   );
   const canOpen = useCallback(
     (source: AssistantFileLinkSource) =>
-      canOpenAssistantFileLink(source, context.configRef.current.workspaceRoot),
+      canOpenAssistantFileLink(source, context.configRef.current),
     [context.configRef],
   );
   const canResolveFile = useCallback(
     (source: AssistantFileLinkSource) =>
-      canResolveAssistantFileLinkToFile(source, context.configRef.current.workspaceRoot),
+      canResolveAssistantFileLinkToFile(source, context.configRef.current),
     [context.configRef],
   );
 
@@ -176,6 +179,7 @@ function openAssistantFileLink(input: {
   const capturedConfig = input.context.configRef.current;
   const capturedResolution = classifyForResolution(input.source, {
     workspaceRoot: capturedConfig.workspaceRoot,
+    relativePathBase: capturedConfig.relativePathBase,
   });
 
   if (capturedResolution.kind === "resolved") {
@@ -233,17 +237,17 @@ function openAssistantFileLink(input: {
 
 function canOpenAssistantFileLink(
   source: AssistantFileLinkSource,
-  workspaceRoot: string | undefined,
+  context: AssistantFileLinkContext,
 ): boolean {
-  const resolution = classifyForResolution(source, { workspaceRoot });
+  const resolution = classifyForResolution(source, context);
   return resolution.kind === "needsLookup" || resolution.value.kind !== "ignored";
 }
 
 function canResolveAssistantFileLinkToFile(
   source: AssistantFileLinkSource,
-  workspaceRoot: string | undefined,
+  context: AssistantFileLinkContext,
 ): boolean {
-  const resolution = classifyForResolution(source, { workspaceRoot });
+  const resolution = classifyForResolution(source, context);
   return resolution.kind === "needsLookup" || resolution.value.kind === "file";
 }
 

packages/app/src/components/tool-call-details.tsx

@@ -1,4 +1,4 @@
-import React, { useMemo, type ReactNode } from "react";
+import { useMemo, type ReactNode } from "react";
 import {
   View,
   Text,
@@ -186,48 +186,6 @@ function ShellDetailSection({ command, output, ds }: ShellDetailProps) {
   );
 }
 
-interface WorktreeSetupDetailProps {
-  log: string;
-  branchName: string;
-  worktreePath: string;
-  ds: DetailStyles;
-}
-
-function WorktreeSetupDetailSection({
-  log,
-  branchName,
-  worktreePath,
-  ds,
-}: WorktreeSetupDetailProps) {
-  const setupLog = log.replace(/^\n+/, "");
-  const hasLog = setupLog.length > 0;
-  return (
-    <View style={ds.sectionFillStyle}>
-      <View style={ds.codeBlockFillStyle}>
-        <ScrollView
-          style={ds.codeVerticalScrollStyle}
-          contentContainerStyle={styles.codeVerticalContent}
-          nestedScrollEnabled
-          showsVerticalScrollIndicator
-        >
-          <ScrollView
-            horizontal
-            nestedScrollEnabled
-            showsHorizontalScrollIndicator
-            contentContainerStyle={styles.codeHorizontalContent}
-          >
-            <View style={styles.codeLine} dataSet={CODE_SURFACE_DATASET}>
-              <Text selectable style={styles.scrollText}>
-                {hasLog ? setupLog : `Preparing worktree ${branchName} at ${worktreePath}`}
-              </Text>
-            </View>
-          </ScrollView>
-        </ScrollView>
-      </View>
-    </View>
-  );
-}
-
 function resolveSubAgentFallbackHeader(
   subAgentType: string | null | undefined,
   description: string | null | undefined,
@@ -678,17 +636,7 @@ function buildDetailSections(
       <ShellDetailSection key="shell" command={detail.command} output={detail.output} ds={ds} />,
     ];
   }
-  if (detail.type === "worktree_setup") {
-    return [
-      <WorktreeSetupDetailSection
-        key="worktree-setup"
-        log={detail.log}
-        branchName={detail.branchName}
-        worktreePath={detail.worktreePath}
-        ds={ds}
-      />,
-    ];
-  }
+  if (detail.type === "worktree_setup") return [];
   if (detail.type === "sub_agent") {
     return [
       <SubAgentDetailSection

packages/app/src/composer/index.tsx

@@ -315,6 +315,7 @@ interface PendingFileAttachment {
 }
 
 interface RenderAttachmentTrayArgs {
+  serverId: string;
   selectedAttachments: ComposerAttachment[];
   pendingFiles: PendingFileAttachment[];
   isComposerLocked: boolean;
@@ -331,6 +332,7 @@ interface RenderAttachmentTrayArgs {
 
 function renderAttachmentTray(args: RenderAttachmentTrayArgs): ReactElement | null {
   const {
+    serverId,
     selectedAttachments,
     pendingFiles,
     isComposerLocked,
@@ -343,6 +345,7 @@ function renderAttachmentTray(args: RenderAttachmentTrayArgs): ReactElement | nu
     <View style={styles.attachmentTray} testID="composer-attachment-tray">
       {selectedAttachments.map((attachment, index) =>
         renderComposerAttachmentPill({
+          serverId,
           attachment,
           index,
           disabled: isComposerLocked,
@@ -393,6 +396,7 @@ function renderQueueTrack(args: RenderQueueTrackArgs): ReactElement | null {
 }
 
 interface RenderComposerAttachmentPillArgs {
+  serverId: string;
   attachment: ComposerAttachment;
   index: number;
   disabled: boolean;
@@ -453,6 +457,7 @@ function renderComposerAttachmentPill(args: RenderComposerAttachmentPillArgs): R
   if (attachment.kind === "plugin_resource") {
     return (
       <PluginResourceAttachmentPill
+        serverId={args.serverId}
         key={`${attachment.pluginId}:${attachment.sourceId}:${attachment.item.id}`}
         attachment={attachment}
         index={index}
@@ -2295,6 +2300,7 @@ function ComposerContentImpl({
   const attachmentTray = useMemo(
     () =>
       renderAttachmentTray({
+        serverId,
         selectedAttachments,
         pendingFiles,
         isComposerLocked,
@@ -2314,6 +2320,7 @@ function ComposerContentImpl({
       handleOpenAttachment,
       handleRemoveAttachment,
       isComposerLocked,
+      serverId,
       selectedAttachments,
       pendingFiles,
       t,

packages/app/src/contexts/session-context.tsx

@@ -56,10 +56,7 @@ export type { DraftInput } from "@/stores/draft-store";
 export type {
   Agent,
   ExplorerEntry,
-  ExplorerFile,
   ExplorerEntryKind,
-  ExplorerFileKind,
-  ExplorerEncoding,
   AgentFileExplorerState,
 } from "@/stores/session-store";
 

packages/app/src/file-explorer/read-result.test.ts

@@ -1,34 +0,0 @@
-import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
-import { describe, expect, it } from "vitest";
-import { explorerFileFromReadResult } from "./read-result";
-
-function textRead(bytes: Uint8Array): FileReadResult {
-  return {
-    bytes,
-    mime: "text/plain",
-    size: bytes.byteLength,
-    path: "notes.txt",
-    kind: "text",
-    modifiedAt: "2026-07-21T00:00:00.000Z",
-  };
-}
-
-describe("explorerFileFromReadResult", () => {
-  it("records and hides a leading UTF-8 BOM", () => {
-    const file = explorerFileFromReadResult(
-      textRead(new Uint8Array([0xef, 0xbb, 0xbf, 0x68, 0x69])),
-    );
-
-    expect(file).toMatchObject({ content: "hi", hasBom: true });
-  });
-
-  it("does not mark BOM-free text or non-leading U+FEFF as BOM files", () => {
-    const plain = explorerFileFromReadResult(textRead(new TextEncoder().encode("hi")));
-    const embedded = explorerFileFromReadResult(
-      textRead(new Uint8Array([0x68, 0x69, 0xef, 0xbb, 0xbf])),
-    );
-
-    expect(plain.hasBom).toBe(false);
-    expect(embedded.hasBom).toBe(false);
-  });
-});

packages/app/src/file-explorer/read-result.ts

@@ -1,21 +0,0 @@
-import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
-import type { ExplorerFile } from "@/stores/session-store";
-
-export function explorerFileFromReadResult(file: FileReadResult): ExplorerFile {
-  const isText = file.kind === "text";
-  return {
-    path: file.path,
-    kind: file.kind,
-    encoding: isText ? "utf-8" : "none",
-    content: isText ? new TextDecoder().decode(file.bytes) : undefined,
-    hasBom: isText && hasUtf8Bom(file.bytes),
-    mimeType: file.mime,
-    size: file.size,
-    modifiedAt: file.modifiedAt,
-    revision: file.revision,
-  };
-}
-
-function hasUtf8Bom(bytes: Uint8Array): boolean {
-  return bytes.length >= 3 && bytes[0] === 0xef && bytes[1] === 0xbb && bytes[2] === 0xbf;
-}

packages/app/src/file-pane/bar.tsx

@@ -1,126 +1,42 @@
-import { Text, View } from "react-native";
-import { StyleSheet, withUnistyles } from "react-native-unistyles";
+import { View } from "react-native";
+import { StyleSheet } from "react-native-unistyles";
 import { useTranslation } from "react-i18next";
-import { LoadingSpinner } from "@/components/ui/loading-spinner";
 import { PaneContentToolbar } from "@/components/ui/pane-content-toolbar";
-import { SegmentedControl } from "@/components/ui/segmented-control";
-import type { Theme } from "@/styles/theme";
-import { FileConflictAlert, type FileConflictAlertState } from "./conflict-alert";
-import type { FileEditorStatus } from "./editor/model";
+import {
+  FilePanelBarMenu,
+  FilePanelSwitcher,
+  useFilePanelChoiceSnapshot,
+  type FilePanelChoice,
+} from "@/file-panels";
 
-const ThemedSpinner = withUnistyles(LoadingSpinner);
-const spinnerMapping = (theme: Theme) => ({ color: theme.colors.foregroundMuted });
-
-export function FilePanelBar({
-  size,
-  lineCount,
-  mode,
-  onModeChange,
-  editorStatus,
-  cursor,
-  vimMode,
-  conflict,
-}: {
-  size: number;
-  lineCount?: number;
-  mode?: "preview" | "source";
-  onModeChange?(mode: "preview" | "source"): void;
-  editorStatus?: FileEditorStatus;
-  cursor?: { line: number; column: number };
-  vimMode?: string | null;
-  conflict?: FileConflictAlertState;
-}) {
+/**
+ * The file tab's bar: the switcher between the file's panels, "Open with…", and whether the panel
+ * has unsaved changes. Shown only when the file has more than one panel; the panel shows the rest.
+ */
+export function FilePanelBar({ choice, modified }: { choice: FilePanelChoice; modified: boolean }) {
   const { t } = useTranslation();
-  const previewModes = [
-    {
-      value: "preview" as const,
-      label: t("panels.file.editor.preview"),
-      testID: "file-mode-preview",
-    },
-    { value: "source" as const, label: t("panels.file.editor.source"), testID: "file-mode-source" },
-  ];
+  const { openWith } = useFilePanelChoiceSnapshot(choice);
+  if (!openWith) return null;
   return (
     <View style={styles.chrome}>
       <PaneContentToolbar testID="file-panel-bar">
         <View style={styles.row}>
-          <View style={styles.metadata}>
-            <Text
-              style={styles.whisper}
-              accessibilityLabel={t("panels.file.editor.fileSize", { size: formatFileSize(size) })}
-            >
-              {formatFileSize(size)}
-            </Text>
-            {lineCount !== undefined ? (
-              <Text
-                style={styles.whisper}
-                accessibilityLabel={t("panels.file.editor.lines", { count: lineCount })}
-              >
-                {t("panels.file.editor.lines", { count: lineCount })}
-              </Text>
-            ) : null}
-          </View>
-          <View
-            style={styles.status}
-            accessibilityLabel={
-              editorStatus
-                ? t("panels.file.editor.editorStatus", { status: editorStatus })
-                : undefined
-            }
-          >
-            {editorStatus === "dirty" ? (
-              <View
-                style={styles.dirtyDot}
-                accessibilityLabel={t("panels.file.editor.unsavedChanges")}
-              />
-            ) : null}
-            {editorStatus === "saving" ? (
-              <>
-                <ThemedSpinner size={14} uniProps={spinnerMapping} />
-                <Text style={styles.secondary}>{t("panels.file.editor.saving")}</Text>
-              </>
-            ) : null}
-            {editorStatus === "error" ? (
-              <Text style={styles.error}>{t("panels.file.editor.saveFailed")}</Text>
-            ) : null}
-            {vimMode ? (
-              <Text
-                style={styles.vim}
-                accessibilityLabel={t("panels.file.editor.vimMode", { mode: vimMode })}
-              >
-                {vimMode}
-              </Text>
-            ) : null}
-            {cursor ? (
-              <Text
-                style={styles.whisper}
-                accessibilityLabel={t("panels.file.editor.cursor", cursor)}
-              >
-                Ln {cursor.line}, Col {cursor.column}
-              </Text>
-            ) : null}
-          </View>
-          {mode && onModeChange ? (
-            <SegmentedControl
-              size="xs"
-              value={mode}
-              onValueChange={onModeChange}
-              testID="file-preview-mode"
-              options={previewModes}
+          <View style={styles.spacer} />
+          {modified ? (
+            <View
+              style={styles.modifiedDot}
+              accessibilityLabel={t("panels.file.editor.unsavedChanges")}
+              testID="file-panel-modified"
             />
           ) : null}
+          <FilePanelSwitcher choice={choice} />
+          <FilePanelBarMenu choice={choice} />
         </View>
       </PaneContentToolbar>
-      {conflict ? <FileConflictAlert state={conflict} /> : null}
     </View>
   );
 }
 
-function formatFileSize(size: number): string {
-  if (size < 1024) return `${size} B`;
-  if (size < 1024 * 1024) return `${(size / 1024).toFixed(1)} KB`;
-  return `${(size / (1024 * 1024)).toFixed(1)} MB`;
-}
-
 const styles = StyleSheet.create((theme) => ({
   chrome: {
     flexShrink: 0,
@@ -132,31 +48,11 @@ const styles = StyleSheet.create((theme) => ({
     gap: theme.spacing[3],
     paddingHorizontal: theme.spacing[3],
   },
-  metadata: {
-    flex: 1,
-    minWidth: 0,
-    flexDirection: "row",
-    alignItems: "center",
-    gap: theme.spacing[2],
-  },
-  secondary: { color: theme.colors.foregroundMuted, fontSize: theme.fontSize.sm },
-  whisper: { color: theme.colors.foregroundExtraMuted, fontSize: theme.fontSize.sm },
-  error: { color: theme.colors.palette.red[300], fontSize: theme.fontSize.sm },
-  dirtyDot: {
+  spacer: { flex: 1 },
+  modifiedDot: {
     width: 6,
     height: 6,
     borderRadius: theme.borderRadius.full,
     backgroundColor: theme.colors.foregroundExtraMuted,
   },
-  status: {
-    flexShrink: 0,
-    flexDirection: "row",
-    alignItems: "center",
-    gap: theme.spacing[2],
-  },
-  vim: {
-    color: theme.colors.foregroundMuted,
-    fontFamily: theme.fontFamily.mono,
-    fontSize: theme.fontSize.sm,
-  },
 }));

packages/app/src/file-pane/editor/model.test.ts

@@ -1,652 +0,0 @@
-import { describe, expect, test } from "vitest";
-import type { FileVersion, FileWriteResult } from "@getpaseo/protocol/messages";
-import {
-  FileEditorModel,
-  getFileConflictCallout,
-  type FileEditorClock,
-  type FileEditorFile,
-  type FileEditorObservation,
-  type FileEditorSession,
-  type FileObservationSource,
-} from "./model";
-
-class TestClock implements FileEditorClock {
-  private callback: (() => void) | null = null;
-
-  setTimeout(callback: () => void): ReturnType<typeof setTimeout> {
-    this.callback = callback;
-    return 1 as unknown as ReturnType<typeof setTimeout>;
-  }
-
-  clearTimeout(): void {
-    this.callback = null;
-  }
-
-  fire(): void {
-    const callback = this.callback;
-    this.callback = null;
-    callback?.();
-  }
-}
-
-class FileSession implements FileEditorSession {
-  file: FileEditorFile;
-  writes: Array<{ content: string; expectedModifiedAt: string; expectedRevision?: string }> = [];
-  nextWrite: FileWriteResult | Error | null = null;
-  private pendingWrite: Promise<FileWriteResult> | null = null;
-  private resolvePendingWrite: ((result: FileWriteResult) => void) | null = null;
-
-  constructor(file: FileEditorFile) {
-    this.file = file;
-  }
-
-  async write(input: {
-    content: string;
-    expectedModifiedAt: string;
-    expectedRevision?: string;
-  }): Promise<FileWriteResult> {
-    this.writes.push(input);
-    if (this.pendingWrite) return this.pendingWrite;
-    if (this.nextWrite instanceof Error) throw this.nextWrite;
-    if (this.nextWrite) return this.nextWrite;
-    return {
-      status: "written",
-      modifiedAt: "2026-07-18T00:00:01.000Z",
-      size: input.content.length,
-    };
-  }
-
-  holdNextWrite(): void {
-    this.pendingWrite = new Promise((resolve) => {
-      this.resolvePendingWrite = resolve;
-    });
-  }
-
-  finishHeldWrite(result: FileWriteResult): void {
-    this.resolvePendingWrite?.(result);
-    this.pendingWrite = null;
-    this.resolvePendingWrite = null;
-  }
-}
-
-class ObservationSource implements FileObservationSource {
-  observation: FileEditorObservation | null;
-  refreshes = 0;
-  private readonly listeners = new Set<() => void>();
-
-  constructor(observation: FileEditorObservation | null) {
-    this.observation = observation;
-  }
-
-  subscribe(listener: () => void): () => void {
-    this.listeners.add(listener);
-    return () => this.listeners.delete(listener);
-  }
-
-  getObservation(): FileEditorObservation | null {
-    return this.observation;
-  }
-
-  refresh = (): void => {
-    this.refreshes += 1;
-  };
-
-  emit(observation: FileEditorObservation): void {
-    this.observation = observation;
-    for (const listener of this.listeners) listener();
-  }
-}
-
-function ready(
-  modifiedAt = "2026-07-18T00:00:00.000Z",
-  size = 3,
-): Extract<FileVersion, { status: "ready" }> {
-  return { status: "ready", cwd: "/workspace", path: "file.ts", size, modifiedAt };
-}
-
-interface MakeModelInput {
-  content?: string;
-  hasBom?: boolean;
-}
-
-function makeModel(input: MakeModelInput = {}) {
-  const file = {
-    content: input.content ?? "one",
-    hasBom: input.hasBom ?? false,
-    version: ready() as Extract<FileVersion, { status: "ready" }>,
-  };
-  const session = new FileSession(file);
-  const clock = new TestClock();
-  return { model: new FileEditorModel({ file, session, clock }), session, clock };
-}
-
-function observeFile(model: FileEditorModel, file: FileEditorFile): void {
-  model.receiveFileObservation({ status: "ready", file });
-}
-
-function observeVersion(model: FileEditorModel, version: FileEditorObservation): void {
-  model.receiveFileObservation(version);
-}
-
-describe("FileEditorModel", () => {
-  test("tracks whether the current buffer differs from persisted content", async () => {
-    const { model } = makeModel();
-
-    expect(model.getSnapshot().modified).toBe(false);
-    model.edit("two");
-    expect(model.getSnapshot().modified).toBe(true);
-    model.edit("one");
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", modified: false });
-
-    model.edit("saved");
-    await model.save();
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", modified: false });
-  });
-
-  test("adopts a precise revision for otherwise unchanged initial metadata", () => {
-    const { model } = makeModel();
-
-    observeFile(model, {
-      content: "one",
-      hasBom: false,
-      version: { ...ready(), revision: "precise-revision" },
-    });
-
-    expect(model.getSnapshot().observedVersion).toMatchObject({ revision: "precise-revision" });
-  });
-
-  test("adopts an unchanged disk revision without disturbing a dirty buffer", async () => {
-    const { model, session } = makeModel();
-    model.edit("local");
-    observeFile(model, {
-      content: "one",
-      hasBom: false,
-      version: { ...ready(), revision: "replacement-revision" },
-    });
-
-    expect(model.getSnapshot()).toMatchObject({ status: "dirty", content: "local" });
-    await model.save();
-
-    expect(session.writes).toEqual([
-      {
-        content: "local",
-        expectedModifiedAt: "2026-07-18T00:00:00.000Z",
-        expectedRevision: "replacement-revision",
-      },
-    ]);
-  });
-
-  test("adopts an external BOM change before saving a dirty buffer", async () => {
-    const { model, session } = makeModel();
-    model.edit("local");
-    observeFile(model, {
-      content: "one",
-      hasBom: true,
-      version: { ...ready(), revision: "replacement-revision" },
-    });
-
-    await model.save();
-
-    expect(session.writes).toEqual([
-      {
-        content: "\uFEFFlocal",
-        expectedModifiedAt: "2026-07-18T00:00:00.000Z",
-        expectedRevision: "replacement-revision",
-      },
-    ]);
-  });
-
-  test("conflicts when a same-content observation changes the BOM during a save", async () => {
-    const { model, session } = makeModel();
-    session.holdNextWrite();
-    model.edit("saved");
-    const save = model.save();
-    observeFile(model, {
-      content: "saved",
-      hasBom: true,
-      version: ready("2026-07-18T00:00:02.000Z", 6),
-    });
-    session.finishHeldWrite({
-      status: "written",
-      modifiedAt: "2026-07-18T00:00:01.000Z",
-      size: 5,
-    });
-
-    await save;
-
-    expect(model.getSnapshot()).toMatchObject({
-      status: "conflict",
-      observedVersion: { modifiedAt: "2026-07-18T00:00:02.000Z" },
-    });
-  });
-
-  test("ignores a settled observation that was already consumed", () => {
-    const { model } = makeModel();
-    const observation: FileEditorObservation = {
-      status: "ready",
-      file: { content: "one", hasBom: false, version: ready() },
-    };
-    let emissions = 0;
-    model.subscribe(() => {
-      emissions += 1;
-    });
-    model.receiveFileObservation(observation);
-    const emissionsAfterFirstDelivery = emissions;
-
-    model.receiveFileObservation(observation);
-
-    expect(emissions).toBe(emissionsAfterFirstDelivery);
-  });
-
-  test("does not replay the pre-save observation while its refresh is pending", async () => {
-    const { model } = makeModel();
-    const observation: FileEditorObservation = {
-      status: "ready",
-      file: { content: "one", hasBom: false, version: ready() },
-    };
-    model.receiveFileObservation(observation);
-    model.edit("saved");
-    await model.save();
-
-    model.receiveFileObservation(observation);
-
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "saved" });
-  });
-
-  test("does not reload stale bytes after a write conflict", async () => {
-    const { model, session } = makeModel();
-    session.nextWrite = {
-      status: "conflict",
-      version: ready("2026-07-18T00:00:02.000Z", 8),
-    };
-    model.edit("important local work");
-    await model.save();
-
-    await model.reload();
-
-    expect(model.getSnapshot()).toMatchObject({
-      status: "conflict",
-      content: "important local work",
-      observedVersion: { modifiedAt: "2026-07-18T00:00:02.000Z" },
-    });
-  });
-
-  test("reloads a write conflict only after refreshed bytes arrive", async () => {
-    const { model, session } = makeModel();
-    const source = new ObservationSource({
-      status: "ready",
-      file: { content: "one", hasBom: false, version: ready() },
-    });
-    model.connectFileObservations(source);
-    session.nextWrite = {
-      status: "conflict",
-      version: ready("2026-07-18T00:00:02.000Z", 4),
-    };
-    model.edit("local");
-    await model.save();
-
-    await model.reload();
-    expect(source.refreshes).toBe(1);
-    expect(model.getSnapshot().content).toBe("local");
-    source.emit({
-      status: "ready",
-      file: {
-        content: "disk",
-        hasBom: false,
-        version: ready("2026-07-18T00:00:02.000Z", 4),
-      },
-    });
-
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "disk" });
-  });
-
-  test("abandons a deferred reload when its refresh fails", async () => {
-    const { model, session } = makeModel();
-    const source = new ObservationSource({
-      status: "ready",
-      file: { content: "one", hasBom: false, version: ready() },
-    });
-    model.connectFileObservations(source);
-    session.nextWrite = {
-      status: "conflict",
-      version: ready("2026-07-18T00:00:02.000Z", 4),
-    };
-    model.edit("local");
-    await model.save();
-    await model.reload();
-    source.emit({
-      status: "error",
-      cwd: "/workspace",
-      path: "file.ts",
-      error: "File unavailable.",
-    });
-    model.edit("new local work");
-
-    source.emit({
-      status: "ready",
-      file: {
-        content: "disk",
-        hasBom: false,
-        version: ready("2026-07-18T00:00:03.000Z", 4),
-      },
-    });
-
-    expect(model.getSnapshot()).toMatchObject({ status: "conflict", content: "new local work" });
-  });
-
-  test("keeps a newer edit modified when an older save finishes", async () => {
-    const { model, session } = makeModel();
-    session.holdNextWrite();
-    model.edit("saving");
-
-    const save = model.save();
-    model.edit("newer edit");
-    session.finishHeldWrite({
-      status: "written",
-      modifiedAt: "2026-07-18T00:00:01.000Z",
-      size: 6,
-    });
-    await save;
-
-    expect(model.getSnapshot()).toMatchObject({
-      status: "dirty",
-      content: "newer edit",
-      modified: true,
-    });
-  });
-
-  test("autosaves the latest edit after inactivity", async () => {
-    const { model, session, clock } = makeModel();
-
-    model.edit("two");
-    model.edit("three");
-    clock.fire();
-    await Promise.resolve();
-
-    expect(session.writes).toEqual([
-      { content: "three", expectedModifiedAt: "2026-07-18T00:00:00.000Z" },
-    ]);
-    expect(model.getSnapshot().status).toBe("clean");
-  });
-
-  test("keeps CRLF content in file form", async () => {
-    const { model, session } = makeModel({ content: "one\r\ntwo\r\n" });
-
-    expect(model.getSnapshot()).toMatchObject({
-      content: "one\r\ntwo\r\n",
-      lineSeparator: "\r\n",
-    });
-    model.edit("one\r\ntwo\r\nthree\r\n");
-    await model.save();
-
-    expect(session.writes).toEqual([
-      {
-        content: "one\r\ntwo\r\nthree\r\n",
-        expectedModifiedAt: "2026-07-18T00:00:00.000Z",
-      },
-    ]);
-  });
-
-  test("restores a UTF-8 BOM before writing a CRLF file", async () => {
-    const { model, session } = makeModel({ content: "one\r\n", hasBom: true });
-
-    model.edit("saved\r\n");
-    await model.save();
-    model.edit("saved again\r\n");
-    await model.save();
-
-    expect(session.writes).toEqual([
-      {
-        content: "\uFEFFsaved\r\n",
-        expectedModifiedAt: "2026-07-18T00:00:00.000Z",
-      },
-      {
-        content: "\uFEFFsaved again\r\n",
-        expectedModifiedAt: "2026-07-18T00:00:01.000Z",
-      },
-    ]);
-  });
-
-  test("uses the first line separator when a file mixes styles", () => {
-    const { model } = makeModel({ content: "one\r\ntwo\nthree\r" });
-
-    expect(model.getSnapshot().lineSeparator).toBe("\r\n");
-  });
-
-  test("reloads a clean editor when the disk version changes", async () => {
-    const { model, session } = makeModel();
-    session.file = {
-      content: "external",
-      hasBom: false,
-      version: ready("2026-07-18T00:00:02.000Z", 8) as Extract<FileVersion, { status: "ready" }>,
-    };
-
-    observeFile(model, session.file);
-
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "external" });
-  });
-
-  test("adopts the format from a clean remote refresh", async () => {
-    const { model, session } = makeModel({ content: "local\r\n", hasBom: true });
-    session.file = {
-      content: "remote\n",
-      hasBom: false,
-      version: ready("2026-07-18T00:00:02.000Z", 7) as Extract<FileVersion, { status: "ready" }>,
-    };
-
-    observeFile(model, session.file);
-    expect(model.getSnapshot().lineSeparator).toBe("\n");
-    model.edit("saved\n");
-    await model.save();
-
-    expect(session.writes.at(-1)).toEqual({
-      content: "saved\n",
-      expectedModifiedAt: "2026-07-18T00:00:02.000Z",
-    });
-  });
-
-  test("applies consecutive clean disk observations", () => {
-    const { model } = makeModel();
-    const firstVersion = ready("2026-07-18T00:00:02.000Z", 5);
-    const latestVersion = ready("2026-07-18T00:00:03.000Z", 6);
-
-    observeFile(model, { content: "first", hasBom: false, version: firstVersion });
-    observeFile(model, { content: "latest", hasBom: false, version: latestVersion });
-
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "latest" });
-  });
-
-  test("preserves a dirty buffer and overwrites against the newest disk revision", async () => {
-    const { model, session } = makeModel();
-    model.edit("local");
-    observeFile(model, {
-      content: "disk",
-      hasBom: false,
-      version: ready("2026-07-18T00:00:02.000Z", 4),
-    });
-
-    expect(model.getSnapshot()).toMatchObject({ status: "conflict", content: "local" });
-    await model.overwrite();
-
-    expect(session.writes).toEqual([
-      { content: "local", expectedModifiedAt: "2026-07-18T00:00:02.000Z" },
-    ]);
-    expect(model.getSnapshot().status).toBe("clean");
-  });
-
-  test("keeps the local CRLF and BOM when overwriting a conflict", async () => {
-    const { model, session } = makeModel({ content: "one\r\n", hasBom: true });
-    model.edit("local\r\n");
-    observeFile(model, {
-      content: "disk",
-      hasBom: false,
-      version: ready("2026-07-18T00:00:02.000Z", 4),
-    });
-
-    await model.overwrite();
-
-    expect(session.writes).toEqual([
-      {
-        content: "\uFEFFlocal\r\n",
-        expectedModifiedAt: "2026-07-18T00:00:02.000Z",
-      },
-    ]);
-  });
-
-  test("reload discards a conflicted local buffer for the disk contents", async () => {
-    const { model, session } = makeModel();
-    model.edit("local");
-    const diskVersion = ready("2026-07-18T00:00:02.000Z", 4) as Extract<
-      FileVersion,
-      { status: "ready" }
-    >;
-    session.file = { content: "disk", hasBom: false, version: diskVersion };
-    observeFile(model, session.file);
-
-    await model.reload();
-
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "disk" });
-  });
-
-  test("adopts the remote format when reloading a conflict", async () => {
-    const { model, session } = makeModel({ content: "one\r\n", hasBom: true });
-    model.edit("local\r\n");
-    const diskVersion = ready("2026-07-18T00:00:02.000Z", 5) as Extract<
-      FileVersion,
-      { status: "ready" }
-    >;
-    session.file = { content: "disk\n", hasBom: false, version: diskVersion };
-    observeFile(model, session.file);
-
-    await model.reload();
-    model.edit("saved\n");
-    await model.save();
-
-    expect(session.writes.at(-1)).toEqual({
-      content: "saved\n",
-      expectedModifiedAt: "2026-07-18T00:00:02.000Z",
-    });
-  });
-
-  test("reports failed saves without losing the local buffer", async () => {
-    const { model, session } = makeModel();
-    session.nextWrite = new Error("disk full");
-    model.edit("important local work");
-
-    await model.save();
-
-    expect(model.getSnapshot()).toMatchObject({
-      status: "error",
-      content: "important local work",
-      error: "disk full",
-    });
-  });
-
-  test("a deletion conflicts with local changes and stops autosave", () => {
-    const { model, session, clock } = makeModel();
-    model.edit("local");
-    observeVersion(model, { status: "missing", cwd: "/workspace", path: "file.ts" });
-
-    clock.fire();
-
-    expect(model.getSnapshot().status).toBe("conflict");
-    expect(session.writes).toEqual([]);
-  });
-
-  test("clears a transient check error when the recovered file is unchanged", () => {
-    const { model } = makeModel();
-    observeVersion(model, {
-      status: "error",
-      cwd: "/workspace",
-      path: "file.ts",
-      error: "Requested path is not a file",
-    });
-
-    observeFile(model, { content: "one", hasBom: false, version: ready() });
-
-    expect(model.getSnapshot()).toMatchObject({
-      status: "clean",
-      modified: false,
-      observedVersion: { status: "ready" },
-      error: null,
-    });
-  });
-
-  test("resumes autosave when a dirty file recovers unchanged from a check error", async () => {
-    const { model, session, clock } = makeModel();
-    model.edit("local");
-    observeVersion(model, {
-      status: "error",
-      cwd: "/workspace",
-      path: "file.ts",
-      error: "Requested path is not a file",
-    });
-
-    observeFile(model, { content: "one", hasBom: false, version: ready() });
-    clock.fire();
-    await Promise.resolve();
-
-    expect(model.getSnapshot()).toMatchObject({ status: "clean", modified: false });
-    expect(session.writes).toEqual([
-      { content: "local", expectedModifiedAt: "2026-07-18T00:00:00.000Z" },
-    ]);
-  });
-
-  test("dispose cancels pending autosave", () => {
-    const { model, session, clock } = makeModel();
-    model.edit("local");
-
-    model.dispose();
-    clock.fire();
-
-    expect(session.writes).toEqual([]);
-  });
-
-  test("suspends a pending autosave while close confirmation is active", async () => {
-    const { model, session, clock } = makeModel();
-    model.edit("local");
-
-    const resume = model.suspendAutosave();
-    clock.fire();
-    expect(session.writes).toEqual([]);
-
-    resume();
-    clock.fire();
-    await Promise.resolve();
-    expect(session.writes).toHaveLength(1);
-  });
-
-  test("maps conflict versions to one exhaustive callout state", () => {
-    const { model } = makeModel();
-    const snapshot = model.getSnapshot();
-
-    expect(getFileConflictCallout(snapshot)).toBeNull();
-    expect(
-      getFileConflictCallout({
-        ...snapshot,
-        status: "conflict",
-        modified: true,
-        observedVersion: ready("2026-07-18T00:00:01.000Z"),
-      }),
-    ).toEqual({ kind: "changed", canOverwrite: true });
-    expect(
-      getFileConflictCallout({
-        ...snapshot,
-        status: "conflict",
-        observedVersion: { status: "missing", cwd: "/workspace", path: "file.ts" },
-      }),
-    ).toEqual({ kind: "deleted" });
-    expect(
-      getFileConflictCallout({
-        ...snapshot,
-        status: "conflict",
-        observedVersion: {
-          status: "error",
-          cwd: "/workspace",
-          path: "file.ts",
-          error: "unreadable",
-        },
-      }),
-    ).toEqual({ kind: "checkFailed" });
-  });
-});

packages/app/src/file-pane/editor/model.ts

@@ -1,402 +0,0 @@
-import type { FileVersion, FileWriteResult } from "@getpaseo/protocol/messages";
-
-export type FileEditorStatus = "clean" | "dirty" | "saving" | "conflict" | "error";
-export type FileLineSeparator = "\n" | "\r\n" | "\r";
-
-export interface FileEditorSnapshot {
-  status: FileEditorStatus;
-  content: string;
-  lineSeparator: FileLineSeparator;
-  modified: boolean;
-  version: FileVersion;
-  observedVersion: FileVersion;
-  error: string | null;
-}
-
-export type FileConflictCallout =
-  | { kind: "changed"; canOverwrite: boolean }
-  | { kind: "deleted" }
-  | { kind: "checkFailed" };
-
-export interface FileEditorFile {
-  content: string;
-  hasBom: boolean;
-  version: Extract<FileVersion, { status: "ready" }>;
-}
-
-export interface FileEditorSession {
-  write(input: {
-    content: string;
-    expectedModifiedAt: string;
-    expectedRevision?: string;
-  }): Promise<FileWriteResult>;
-}
-
-export type FileEditorObservation =
-  | { status: "ready"; file: FileEditorFile }
-  | Extract<FileVersion, { status: "missing" | "error" }>;
-
-export interface FileObservationSource {
-  subscribe(listener: () => void): () => void;
-  getObservation(): FileEditorObservation | null;
-  refresh(): void;
-}
-
-type ObservedDiskState = FileEditorObservation | { status: "unsettled"; version: FileVersion };
-
-export interface FileEditorClock {
-  setTimeout(callback: () => void, delayMs: number): ReturnType<typeof setTimeout>;
-  clearTimeout(handle: ReturnType<typeof setTimeout>): void;
-}
-
-const systemClock: FileEditorClock = {
-  setTimeout(callback, delay) {
-    return globalThis.setTimeout(callback, delay);
-  },
-  clearTimeout(handle) {
-    globalThis.clearTimeout(handle);
-  },
-};
-
-export class FileEditorModel {
-  private readonly session: FileEditorSession;
-  private readonly clock: FileEditorClock;
-  private readonly listeners = new Set<() => void>();
-  private snapshot: FileEditorSnapshot;
-  private autosave: ReturnType<typeof setTimeout> | null = null;
-  private saveSequence = 0;
-  private disposed = false;
-  private observedWhileSaving: FileEditorObservation | null = null;
-  private observed: ObservedDiskState;
-  private lastReceivedObservation: FileEditorObservation | null = null;
-  private refreshObservation: (() => void) | null = null;
-  private reloadRequested = false;
-  private persistedContent: string;
-  private hasBom: boolean;
-  private unsubscribeObservationSource: (() => void) | null = null;
-
-  constructor(input: {
-    file: FileEditorFile;
-    session: FileEditorSession;
-    clock?: FileEditorClock;
-  }) {
-    this.session = input.session;
-    this.clock = input.clock ?? systemClock;
-    this.persistedContent = input.file.content;
-    this.hasBom = input.file.hasBom;
-    this.observed = { status: "ready", file: input.file };
-    this.snapshot = {
-      status: "clean",
-      content: input.file.content,
-      lineSeparator: detectLineSeparator(input.file.content),
-      modified: false,
-      version: input.file.version,
-      observedVersion: input.file.version,
-      error: null,
-    };
-  }
-
-  subscribe = (listener: () => void): (() => void) => {
-    this.listeners.add(listener);
-    return () => this.listeners.delete(listener);
-  };
-
-  getSnapshot = (): FileEditorSnapshot => this.snapshot;
-
-  connectFileObservations(source: FileObservationSource): void {
-    this.disconnectFileObservations();
-    this.refreshObservation = source.refresh;
-    const receiveObservation = () => {
-      const observation = source.getObservation();
-      if (observation) this.receiveFileObservation(observation);
-    };
-    this.unsubscribeObservationSource = source.subscribe(receiveObservation);
-    receiveObservation();
-  }
-
-  disconnectFileObservations(): void {
-    this.unsubscribeObservationSource?.();
-    this.unsubscribeObservationSource = null;
-    this.refreshObservation = null;
-  }
-
-  edit(content: string): void {
-    if (this.disposed || content === this.snapshot.content) return;
-    this.reloadRequested = false;
-    const modified = content !== this.persistedContent;
-    let status: FileEditorStatus = modified ? "dirty" : "clean";
-    if (this.snapshot.status === "conflict") {
-      status = "conflict";
-    }
-    this.setSnapshot({ ...this.snapshot, status, content, modified, error: null });
-    if (status === "dirty") this.scheduleAutosave();
-    else this.clearAutosave();
-  }
-
-  async save(): Promise<void> {
-    if (this.disposed || (this.snapshot.status !== "dirty" && this.snapshot.status !== "error")) {
-      return;
-    }
-    if (this.snapshot.observedVersion.status !== "ready") {
-      this.enterConflict(this.snapshot.observedVersion);
-      return;
-    }
-    await this.performWrite(this.snapshot.observedVersion);
-  }
-
-  receiveFileObservation(observation: FileEditorObservation): void {
-    if (this.disposed || observation === this.lastReceivedObservation) return;
-    this.lastReceivedObservation = observation;
-    const version = observationVersion(observation);
-    this.observed = observation;
-    this.setSnapshot({ ...this.snapshot, observedVersion: version });
-    if (this.snapshot.status === "saving") {
-      this.observedWhileSaving = observation;
-      return;
-    }
-    if (observation.status !== "ready") {
-      this.reloadRequested = false;
-      this.enterConflict(version);
-      return;
-    }
-    if (this.reloadRequested) {
-      this.reloadRequested = false;
-      this.applyFile(observation.file);
-      return;
-    }
-    if (observation.file.content === this.persistedContent) {
-      this.adoptUnchangedFile(observation.file);
-      return;
-    }
-    if (this.snapshot.status === "clean") {
-      this.applyFile(observation.file);
-      return;
-    }
-    this.enterConflict(version);
-  }
-
-  async overwrite(): Promise<void> {
-    if (this.disposed || this.snapshot.status !== "conflict") return;
-    if (this.snapshot.observedVersion.status !== "ready") return;
-    await this.performWrite(this.snapshot.observedVersion);
-  }
-
-  async reload(): Promise<void> {
-    if (this.disposed) return;
-    if (this.observed.status !== "ready") {
-      this.reloadRequested = true;
-      this.refreshObservation?.();
-      return;
-    }
-    this.applyFile(this.observed.file);
-  }
-
-  dispose(): void {
-    this.disposed = true;
-    this.reloadRequested = false;
-    this.saveSequence += 1;
-    this.clearAutosave();
-    this.disconnectFileObservations();
-    this.listeners.clear();
-  }
-
-  suspendAutosave(): () => void {
-    const wasScheduled = this.autosave !== null;
-    this.clearAutosave();
-    let resumed = false;
-    return () => {
-      if (resumed || this.disposed) return;
-      resumed = true;
-      if (wasScheduled && this.snapshot.status === "dirty") this.scheduleAutosave();
-    };
-  }
-
-  private async performWrite(
-    expectedVersion: Extract<FileVersion, { status: "ready" }>,
-  ): Promise<void> {
-    this.clearAutosave();
-    const sequence = ++this.saveSequence;
-    const content = this.snapshot.content;
-    const hasBom = this.hasBom;
-    this.observedWhileSaving = null;
-    this.setSnapshot({ ...this.snapshot, status: "saving", error: null });
-    const serializedContent = hasBom ? `\uFEFF${content}` : content;
-    let result: FileWriteResult;
-    try {
-      result = await this.session.write({
-        content: serializedContent,
-        expectedModifiedAt: expectedVersion.modifiedAt,
-        expectedRevision: expectedVersion.revision,
-      });
-    } catch (error) {
-      if (this.disposed || sequence !== this.saveSequence) return;
-      this.setSnapshot({
-        ...this.snapshot,
-        status: "error",
-        error: error instanceof Error ? error.message : String(error),
-      });
-      return;
-    }
-    if (this.disposed || sequence !== this.saveSequence) return;
-    if (result.status === "error") {
-      this.setSnapshot({ ...this.snapshot, status: "error", error: result.error });
-      return;
-    }
-    if (result.status === "conflict") {
-      this.observed = { status: "unsettled", version: result.version };
-      this.enterConflict(result.version);
-      return;
-    }
-
-    const writtenVersion: Extract<FileVersion, { status: "ready" }> = {
-      status: "ready",
-      cwd: this.snapshot.version.cwd,
-      path: this.snapshot.version.path,
-      size: result.size,
-      modifiedAt: result.modifiedAt,
-      revision: result.revision,
-    };
-    const pending = this.takeObservedWhileSaving();
-    this.persistedContent = content;
-    if (pending && !observationMatchesWrite(pending, content, hasBom)) {
-      const pendingVersion = observationVersion(pending);
-      this.observed = pending;
-      this.setSnapshot({
-        ...this.snapshot,
-        status: "conflict",
-        modified: this.snapshot.content !== this.persistedContent,
-        version: writtenVersion,
-        observedVersion: pendingVersion,
-        error: null,
-      });
-      return;
-    }
-    const settledVersion = pending?.status === "ready" ? pending.file.version : writtenVersion;
-    this.observed = pending ?? { status: "unsettled", version: writtenVersion };
-    const modified = this.snapshot.content !== this.persistedContent;
-    this.setSnapshot({
-      ...this.snapshot,
-      status: modified ? "dirty" : "clean",
-      modified,
-      version: settledVersion,
-      observedVersion: settledVersion,
-      error: null,
-    });
-    if (modified) this.scheduleAutosave();
-  }
-
-  private applyFile(file: FileEditorFile): void {
-    this.clearAutosave();
-    this.saveSequence += 1;
-    this.persistedContent = file.content;
-    this.hasBom = file.hasBom;
-    this.observed = { status: "ready", file };
-    this.setSnapshot({
-      status: "clean",
-      content: file.content,
-      lineSeparator: detectLineSeparator(file.content),
-      modified: false,
-      version: file.version,
-      observedVersion: file.version,
-      error: null,
-    });
-  }
-
-  private takeObservedWhileSaving(): FileEditorObservation | null {
-    const observation = this.observedWhileSaving;
-    this.observedWhileSaving = null;
-    return observation;
-  }
-
-  private enterConflict(version: FileVersion): void {
-    this.clearAutosave();
-    this.setSnapshot({
-      ...this.snapshot,
-      status: "conflict",
-      modified: this.snapshot.content !== this.persistedContent,
-      observedVersion: version,
-      error: version.status === "error" ? version.error : null,
-    });
-  }
-
-  private adoptUnchangedFile(file: FileEditorFile): void {
-    this.hasBom = file.hasBom;
-    this.observed = { status: "ready", file };
-    const modified = this.snapshot.content !== this.persistedContent;
-    const recovering = this.snapshot.status === "conflict";
-    let status = this.snapshot.status;
-    if (recovering) status = modified ? "dirty" : "clean";
-    this.setSnapshot({
-      ...this.snapshot,
-      status,
-      modified,
-      version: file.version,
-      observedVersion: file.version,
-      error: recovering ? null : this.snapshot.error,
-    });
-    if (status === "dirty") this.scheduleAutosave();
-    else this.clearAutosave();
-  }
-
-  private scheduleAutosave(): void {
-    this.clearAutosave();
-    this.autosave = this.clock.setTimeout(() => {
-      this.autosave = null;
-      void this.save();
-    }, 800);
-  }
-
-  private clearAutosave(): void {
-    if (!this.autosave) return;
-    this.clock.clearTimeout(this.autosave);
-    this.autosave = null;
-  }
-
-  private setSnapshot(snapshot: FileEditorSnapshot): void {
-    this.snapshot = snapshot;
-    for (const listener of this.listeners) listener();
-  }
-}
-
-export function getFileConflictCallout(snapshot: FileEditorSnapshot): FileConflictCallout | null {
-  if (snapshot.status !== "conflict") return null;
-  switch (snapshot.observedVersion.status) {
-    case "ready":
-      return { kind: "changed", canOverwrite: snapshot.modified };
-    case "missing":
-      return { kind: "deleted" };
-    case "error":
-      return { kind: "checkFailed" };
-    default:
-      return assertNever(snapshot.observedVersion);
-  }
-}
-
-function assertNever(value: never): never {
-  throw new Error(`Unexpected file version: ${JSON.stringify(value)}`);
-}
-
-function detectLineSeparator(content: string): FileLineSeparator {
-  for (let index = 0; index < content.length; index += 1) {
-    const character = content.charCodeAt(index);
-    if (character === 10) return "\n";
-    if (character === 13) return content.charCodeAt(index + 1) === 10 ? "\r\n" : "\r";
-  }
-  return "\n";
-}
-
-function observationVersion(observation: FileEditorObservation): FileVersion {
-  return observation.status === "ready" ? observation.file.version : observation;
-}
-
-function observationMatchesWrite(
-  observation: FileEditorObservation,
-  content: string,
-  hasBom: boolean,
-): boolean {
-  return (
-    observation.status === "ready" &&
-    observation.file.content === content &&
-    observation.file.hasBom === hasBom
-  );
-}

packages/app/src/file-pane/editor/observation-source.test.ts

@@ -1,60 +0,0 @@
-import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
-import { describe, expect, test } from "vitest";
-import type { LiveFileObservation } from "../live-file/model";
-import { createFileObservationSource, type LiveObservationSource } from "./observation-source";
-
-class TestLiveObservationSource implements LiveObservationSource {
-  observation: LiveFileObservation | null;
-
-  constructor(observation: LiveFileObservation | null) {
-    this.observation = observation;
-  }
-
-  subscribe(): () => void {
-    return () => undefined;
-  }
-
-  getObservation(): LiveFileObservation | null {
-    return this.observation;
-  }
-
-  refresh(): void {}
-}
-
-function readyObservation(): LiveFileObservation {
-  const file: FileReadResult = {
-    bytes: new TextEncoder().encode("one"),
-    mime: "text/plain",
-    size: 3,
-    path: "file.ts",
-    kind: "text",
-    modifiedAt: "2026-07-18T00:00:00.000Z",
-    revision: "revision-1",
-  };
-  return {
-    status: "ready",
-    file,
-    version: {
-      status: "ready",
-      cwd: "/workspace",
-      path: "file.ts",
-      size: file.size,
-      modifiedAt: file.modifiedAt,
-      revision: file.revision,
-    },
-  };
-}
-
-describe("createFileObservationSource", () => {
-  test("returns the same editor observation until the live observation changes", () => {
-    const liveFile = new TestLiveObservationSource(readyObservation());
-    const source = createFileObservationSource(liveFile);
-
-    const first = source.getObservation();
-    const repeated = source.getObservation();
-
-    expect(repeated).toBe(first);
-    liveFile.observation = readyObservation();
-    expect(source.getObservation()).not.toBe(first);
-  });
-});

packages/app/src/file-pane/editor/observation-source.ts

@@ -1,50 +0,0 @@
-import { explorerFileFromReadResult } from "@/file-explorer/read-result";
-import type { LiveFileObservation } from "../live-file/model";
-import type { FileEditorObservation, FileObservationSource } from "./model";
-
-export interface LiveObservationSource {
-  subscribe(listener: () => void): () => void;
-  getObservation(): LiveFileObservation | null;
-  refresh(): void;
-}
-
-export function createFileObservationSource(
-  liveFile: LiveObservationSource,
-): FileObservationSource {
-  let liveObservation: LiveFileObservation | null = null;
-  let editorObservation: FileEditorObservation | null = null;
-  return {
-    subscribe: liveFile.subscribe,
-    refresh: liveFile.refresh,
-    getObservation() {
-      const nextLiveObservation = liveFile.getObservation();
-      if (nextLiveObservation === liveObservation) return editorObservation;
-      liveObservation = nextLiveObservation;
-      editorObservation = fileEditorObservation(nextLiveObservation);
-      return editorObservation;
-    },
-  };
-}
-
-function fileEditorObservation(
-  observation: LiveFileObservation | null,
-): FileEditorObservation | null {
-  if (!observation || observation.status !== "ready") return observation;
-  const decodedFile = explorerFileFromReadResult(observation.file);
-  if (decodedFile.kind !== "text" || decodedFile.content === undefined) {
-    return {
-      status: "error",
-      cwd: observation.version.cwd,
-      path: observation.version.path,
-      error: "File is no longer text.",
-    };
-  }
-  return {
-    status: "ready",
-    file: {
-      content: decodedFile.content,
-      hasBom: decodedFile.hasBom,
-      version: observation.version,
-    },
-  };
-}

packages/app/src/file-pane/live-file/hook.ts

@@ -1,61 +0,0 @@
-import type { DaemonClient } from "@getpaseo/client/internal/daemon-client";
-import { useEffect, useMemo, useState, useSyncExternalStore } from "react";
-import { LiveFileModel, type LiveFileSession } from "./model";
-import { SOURCE_PRESENTATION_BUDGETS } from "../source/presentation";
-import { isWeb } from "@/constants/platform";
-
-export function useLiveFile(input: {
-  client: DaemonClient | null;
-  cwd: string | null;
-  path: string | null;
-  enabled: boolean;
-  liveUpdates: boolean;
-}) {
-  const [model] = useState(() => new LiveFileModel());
-  const session = useMemo<LiveFileSession | null>(() => {
-    if (!input.client) return null;
-    const client = input.client;
-    return {
-      subscribe(target, onVersion) {
-        return client.subscribeFile(target, onVersion);
-      },
-      read(target) {
-        return client.readFile(
-          target.cwd,
-          target.path,
-          undefined,
-          SOURCE_PRESENTATION_BUDGETS[isWeb ? "web" : "native"].plain,
-        );
-      },
-    };
-  }, [input.client]);
-
-  useEffect(() => {
-    if (!input.enabled || !session || !input.cwd || !input.path) {
-      model.close();
-      return;
-    }
-    model.open({
-      session,
-      target: { cwd: input.cwd, path: input.path },
-      liveUpdates: input.liveUpdates,
-    });
-    return () => model.close();
-  }, [input.cwd, input.enabled, input.liveUpdates, input.path, model, session]);
-
-  const snapshot = useSyncExternalStore(model.subscribe, model.getSnapshot, model.getSnapshot);
-  return {
-    file: snapshot.observation?.status === "ready" ? snapshot.observation.file : null,
-    error: snapshot.read.status === "error" ? snapshot.read.error : null,
-    // Effects start reads after the first render. An enabled target is therefore
-    // already in the producer's initial/retargeting display state.
-    isFetching:
-      input.enabled &&
-      (snapshot.read.status === "pending" ||
-        (snapshot.read.status === "idle" && snapshot.observation === null)),
-    isRetrying: snapshot.read.status === "pending" && snapshot.read.requested,
-    refresh: model.refresh,
-    model,
-    snapshot,
-  };
-}

packages/app/src/file-pane/live-file/model.test.ts

@@ -1,344 +0,0 @@
-import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
-import type { FileVersion } from "@getpaseo/protocol/messages";
-import { describe, expect, it, vi } from "vitest";
-import { LiveFileModel, type LiveFileSession, type LiveFileSubscription } from "./model";
-
-interface Deferred<T> {
-  promise: Promise<T>;
-  resolve(value: T): void;
-  reject(error: Error): void;
-}
-
-function deferred<T>(): Deferred<T> {
-  let resolve!: (value: T) => void;
-  let reject!: (error: Error) => void;
-  const promise = new Promise<T>((onResolve, onReject) => {
-    resolve = onResolve;
-    reject = onReject;
-  });
-  return { promise, resolve, reject };
-}
-
-function ready(revision = "revision-1"): Extract<FileVersion, { status: "ready" }> {
-  return {
-    status: "ready",
-    cwd: "/workspace",
-    path: "file.ts",
-    size: 3,
-    modifiedAt: "2026-07-30T00:00:00.000Z",
-    revision,
-  };
-}
-
-function file(revision = "revision-1", content = "one"): FileReadResult {
-  return {
-    bytes: new TextEncoder().encode(content),
-    mime: "text/plain",
-    size: content.length,
-    path: "file.ts",
-    kind: "text",
-    modifiedAt: "2026-07-30T00:00:00.000Z",
-    revision,
-  };
-}
-
-class TestLiveFileSession implements LiveFileSession {
-  readonly reads: Deferred<FileReadResult>[] = [];
-  subscribeAttempts = 0;
-  private onVersion: ((version: FileVersion) => void) | null = null;
-  private readonly initial: FileVersion;
-
-  constructor(initial: FileVersion = ready()) {
-    this.initial = initial;
-  }
-
-  async subscribe(
-    _target: { cwd: string; path: string },
-    onVersion: (version: FileVersion) => void,
-  ): Promise<LiveFileSubscription> {
-    this.subscribeAttempts += 1;
-    this.onVersion = onVersion;
-    return { initial: this.initial, unsubscribe: () => (this.onVersion = null) };
-  }
-
-  read(): Promise<FileReadResult> {
-    const request = deferred<FileReadResult>();
-    this.reads.push(request);
-    return request.promise;
-  }
-
-  emit(version: FileVersion): void {
-    this.onVersion?.(version);
-  }
-}
-
-class DeferredSubscribeSession implements LiveFileSession {
-  readonly reads: Deferred<FileReadResult>[] = [];
-  readonly subscription = deferred<LiveFileSubscription>();
-  private onVersion: ((version: FileVersion) => void) | null = null;
-
-  subscribe(
-    _target: { cwd: string; path: string },
-    onVersion: (version: FileVersion) => void,
-  ): Promise<LiveFileSubscription> {
-    this.onVersion = onVersion;
-    return this.subscription.promise;
-  }
-
-  read(): Promise<FileReadResult> {
-    const request = deferred<FileReadResult>();
-    this.reads.push(request);
-    return request.promise;
-  }
-
-  emit(version: FileVersion): void {
-    this.onVersion?.(version);
-  }
-}
-
-class FlakySubscriptionSession extends TestLiveFileSession {
-  override async subscribe(
-    target: { cwd: string; path: string },
-    onVersion: (version: FileVersion) => void,
-  ): Promise<LiveFileSubscription> {
-    if (this.subscribeAttempts === 0) {
-      this.subscribeAttempts += 1;
-      throw new Error("Connection closed.");
-    }
-    return super.subscribe(target, onVersion);
-  }
-}
-
-async function waitForRead(
-  session: { reads: Deferred<FileReadResult>[] },
-  count: number,
-): Promise<void> {
-  await vi.waitFor(() => expect(session.reads).toHaveLength(count));
-}
-
-describe("LiveFileModel", () => {
-  it("reports initial and read-pending work before any terminal observation", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({ session, target: { cwd: "/workspace", path: "file.ts" }, liveUpdates: false });
-    await waitForRead(session, 1);
-    expect(model.getSnapshot()).toEqual({
-      observation: null,
-      read: { status: "pending", requested: false },
-    });
-  });
-
-  it("reports read error as terminal and recovers on refresh", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({ session, target: { cwd: "/workspace", path: "file.ts" }, liveUpdates: false });
-    await waitForRead(session, 1);
-    session.reads[0].reject(new Error("read failed"));
-    await vi.waitFor(() =>
-      expect(model.getSnapshot().read).toEqual({ status: "error", error: "read failed" }),
-    );
-    model.refresh();
-    await waitForRead(session, 2);
-    session.reads[1].resolve(file("revision-2"));
-    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("ready"));
-  });
-  it("does not publish a missing candidate when the following read succeeds", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-    await waitForRead(session, 1);
-    session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getObservation()).toMatchObject({ status: "ready" }));
-    const publishedStatuses: string[] = [];
-    model.subscribe(() => {
-      const observation = model.getObservation();
-      if (observation) publishedStatuses.push(observation.status);
-    });
-
-    session.emit({ status: "missing", cwd: "/workspace", path: "file.ts" });
-    await waitForRead(session, 2);
-    session.reads[1].resolve(file());
-    await vi.waitFor(() => expect(model.getSnapshot().read).toEqual({ status: "idle" }));
-
-    expect(publishedStatuses).not.toContain("missing");
-  });
-
-  it("publishes missing when the following read also fails", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-    await waitForRead(session, 1);
-    session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("ready"));
-
-    session.emit({ status: "missing", cwd: "/workspace", path: "file.ts" });
-    await waitForRead(session, 2);
-    session.reads[1].reject(new Error("File not found."));
-
-    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("missing"));
-  });
-
-  it("preserves a missing candidate for its queued confirming read", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-    await waitForRead(session, 1);
-
-    session.emit({ status: "missing", cwd: "/workspace", path: "file.ts" });
-    session.reads[0].resolve(file());
-    await waitForRead(session, 2);
-    session.reads[1].reject(new Error("File not found."));
-
-    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("missing"));
-  });
-
-  it("recovers only from a read begun after a missing observation", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-    await waitForRead(session, 1);
-    session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getObservation()).toMatchObject({ status: "ready" }));
-
-    model.refresh();
-    await waitForRead(session, 2);
-    session.emit({ status: "missing", cwd: "/workspace", path: "file.ts" });
-    session.reads[1].resolve(file("revision-2", "two"));
-
-    await waitForRead(session, 3);
-    expect(model.getObservation()?.status).toBe("ready");
-    expect(model.getSnapshot().read).toEqual({ status: "pending", requested: true });
-
-    session.reads[2].resolve(file("revision-2", "two"));
-    await vi.waitFor(() => {
-      expect(model.getSnapshot()).toMatchObject({
-        observation: {
-          status: "ready",
-          version: { revision: "revision-2" },
-          file: { revision: "revision-2" },
-        },
-        read: { status: "idle" },
-      });
-    });
-  });
-
-  it("keeps an actionable error visible while refresh fails", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-    await waitForRead(session, 1);
-    session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getObservation()).toMatchObject({ status: "ready" }));
-
-    session.emit({
-      status: "error",
-      cwd: "/workspace",
-      path: "file.ts",
-      error: "Requested path is not a file",
-    });
-    await waitForRead(session, 2);
-    expect(model.getSnapshot().read).toEqual({ status: "pending", requested: false });
-    session.reads[1].reject(new Error("File unavailable."));
-
-    await vi.waitFor(() => {
-      expect(model.getSnapshot()).toMatchObject({
-        observation: { status: "error", error: "Requested path is not a file" },
-        read: { status: "error", error: "File unavailable." },
-      });
-    });
-
-    model.refresh();
-    await waitForRead(session, 3);
-    expect(model.getSnapshot().read).toEqual({ status: "pending", requested: true });
-  });
-
-  it("keeps an update that arrives before the subscription response", async () => {
-    const session = new DeferredSubscribeSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-
-    session.emit(ready("revision-2"));
-    session.subscription.resolve({ initial: ready("revision-1"), unsubscribe() {} });
-
-    await waitForRead(session, 1);
-    expect(model.getObservation()).toBeNull();
-  });
-
-  it("retries a failed subscription when the user refreshes", async () => {
-    const session = new FlakySubscriptionSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-    await waitForRead(session, 1);
-    expect(session.subscribeAttempts).toBe(1);
-
-    session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("ready"));
-    model.refresh();
-
-    await waitForRead(session, 2);
-    expect(session.subscribeAttempts).toBe(2);
-    expect(model.getSnapshot().read).toEqual({ status: "pending", requested: true });
-  });
-
-  it("reads once without subscribing when live updates are disabled", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: false,
-    });
-
-    await waitForRead(session, 1);
-    expect(session.subscribeAttempts).toBe(0);
-    expect(model.getSnapshot().read).toEqual({ status: "pending", requested: false });
-  });
-
-  it("ignores a read that completes after the model closes", async () => {
-    const session = new TestLiveFileSession();
-    const model = new LiveFileModel();
-    model.open({
-      session,
-      target: { cwd: "/workspace", path: "file.ts" },
-      liveUpdates: true,
-    });
-    await waitForRead(session, 1);
-
-    model.close();
-    session.reads[0].resolve(file());
-    await Promise.resolve();
-
-    expect(model.getSnapshot()).toEqual({
-      observation: null,
-      read: { status: "idle" },
-    });
-  });
-});

packages/app/src/file-pane/live-file/model.ts

@@ -1,272 +0,0 @@
-import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
-import type { FileVersion } from "@getpaseo/protocol/messages";
-
-export interface LiveFileTarget {
-  cwd: string;
-  path: string;
-}
-
-export interface LiveFileSubscription {
-  initial: FileVersion;
-  unsubscribe(): void;
-}
-
-export interface LiveFileSession {
-  subscribe(
-    target: LiveFileTarget,
-    onVersion: (version: FileVersion) => void,
-  ): Promise<LiveFileSubscription>;
-  read(target: LiveFileTarget): Promise<FileReadResult>;
-}
-
-export type LiveFileReadState =
-  | { status: "idle" }
-  | { status: "pending"; requested: boolean }
-  | { status: "error"; error: string };
-
-export type LiveFileObservation =
-  | {
-      status: "ready";
-      version: Extract<FileVersion, { status: "ready" }>;
-      file: FileReadResult;
-    }
-  | Extract<FileVersion, { status: "missing" | "error" }>;
-
-export interface LiveFileSnapshot {
-  observation: LiveFileObservation | null;
-  read: LiveFileReadState;
-}
-
-const idleSnapshot: LiveFileSnapshot = {
-  observation: null,
-  read: { status: "idle" },
-};
-
-export class LiveFileModel {
-  private readonly listeners = new Set<() => void>();
-  private snapshot: LiveFileSnapshot = idleSnapshot;
-  private session: LiveFileSession | null = null;
-  private target: LiveFileTarget | null = null;
-  private liveUpdates = false;
-  private unsubscribe: (() => void) | null = null;
-  private subscriptionPending = false;
-  private generation = 0;
-  private issuedReadSequence = 0;
-  private activeReadSequence: number | null = null;
-  private activeReadRequested = false;
-  private observedAfterReadSequence: number | null = null;
-  private candidateVersion: FileVersion | null = null;
-  private refreshQueued = false;
-  private requestedRefreshQueued = false;
-
-  subscribe = (listener: () => void): (() => void) => {
-    this.listeners.add(listener);
-    return () => this.listeners.delete(listener);
-  };
-
-  getSnapshot = (): LiveFileSnapshot => this.snapshot;
-
-  getObservation = (): LiveFileObservation | null => this.snapshot.observation;
-
-  open(input: { session: LiveFileSession; target: LiveFileTarget; liveUpdates: boolean }): void {
-    this.reset();
-    this.session = input.session;
-    this.target = input.target;
-    this.liveUpdates = input.liveUpdates;
-    const generation = this.generation;
-    if (!input.liveUpdates) {
-      this.scheduleRead(false);
-      return;
-    }
-    void this.startSubscription(generation);
-  }
-
-  close(): void {
-    this.reset();
-  }
-
-  refresh = (): void => {
-    if (!this.session || !this.target) return;
-    if (this.liveUpdates && !this.unsubscribe && !this.subscriptionPending) {
-      void this.startSubscription(this.generation);
-    }
-    this.scheduleRead(true);
-  };
-
-  private scheduleRead(requested: boolean): void {
-    if (this.activeReadSequence !== null) {
-      this.refreshQueued = true;
-      this.activeReadRequested ||= requested;
-      this.requestedRefreshQueued ||= requested;
-      if (requested && this.snapshot.read.status === "pending") {
-        this.setSnapshot({ ...this.snapshot, read: { status: "pending", requested: true } });
-      }
-      return;
-    }
-    this.startRead(requested);
-  }
-
-  private reset(): void {
-    this.generation += 1;
-    this.unsubscribe?.();
-    this.unsubscribe = null;
-    this.session = null;
-    this.target = null;
-    this.liveUpdates = false;
-    this.subscriptionPending = false;
-    this.issuedReadSequence = 0;
-    this.activeReadSequence = null;
-    this.activeReadRequested = false;
-    this.observedAfterReadSequence = null;
-    this.candidateVersion = null;
-    this.refreshQueued = false;
-    this.requestedRefreshQueued = false;
-    this.setSnapshot(idleSnapshot);
-  }
-
-  private async startSubscription(generation: number): Promise<void> {
-    const session = this.session;
-    const target = this.target;
-    if (!session || !target) return;
-    this.subscriptionPending = true;
-    let receivedUpdate = false;
-    try {
-      const subscription = await session.subscribe(target, (version) => {
-        if (generation !== this.generation) return;
-        receivedUpdate = true;
-        this.observeVersion(version);
-      });
-      if (generation !== this.generation) {
-        subscription.unsubscribe();
-        return;
-      }
-      this.subscriptionPending = false;
-      this.unsubscribe = subscription.unsubscribe;
-      if (!receivedUpdate) this.observeVersion(subscription.initial);
-    } catch {
-      if (generation !== this.generation) return;
-      this.subscriptionPending = false;
-      this.scheduleRead(false);
-    }
-  }
-
-  private observeVersion(version: FileVersion): void {
-    this.observedAfterReadSequence = this.issuedReadSequence;
-    this.candidateVersion = version;
-    this.scheduleRead(false);
-  }
-
-  private startRead(requested: boolean): void {
-    const session = this.session;
-    const target = this.target;
-    if (!session || !target) return;
-    const generation = this.generation;
-    const sequence = ++this.issuedReadSequence;
-    this.activeReadSequence = sequence;
-    this.activeReadRequested = requested;
-    this.refreshQueued = false;
-    this.requestedRefreshQueued = false;
-    this.setSnapshot({ ...this.snapshot, read: { status: "pending", requested } });
-    void session.read(target).then(
-      (file) => this.finishRead({ generation, sequence, target, file }),
-      (error) => this.failRead({ generation, sequence, target, error }),
-    );
-  }
-
-  private finishRead(input: {
-    generation: number;
-    sequence: number;
-    target: LiveFileTarget;
-    file: FileReadResult;
-  }): void {
-    if (!this.isActiveRead(input.generation, input.sequence)) return;
-    const requested = this.activeReadRequested;
-    this.activeReadSequence = null;
-    this.activeReadRequested = false;
-    if (this.readPredatesLatestObservation(input.sequence)) {
-      this.startRead(requested || this.takeQueuedRequested());
-      return;
-    }
-    this.observedAfterReadSequence = null;
-    this.candidateVersion = null;
-    this.setSnapshot({
-      observation: {
-        status: "ready",
-        file: input.file,
-        version: readyVersion(input.target, input.file),
-      },
-      read: { status: "idle" },
-    });
-    this.startQueuedRead();
-  }
-
-  private failRead(input: {
-    generation: number;
-    sequence: number;
-    target: LiveFileTarget;
-    error: unknown;
-  }): void {
-    if (!this.isActiveRead(input.generation, input.sequence)) return;
-    const requested = this.activeReadRequested;
-    this.activeReadSequence = null;
-    this.activeReadRequested = false;
-    if (this.readPredatesLatestObservation(input.sequence)) {
-      this.startRead(requested || this.takeQueuedRequested());
-      return;
-    }
-    const message = errorMessage(input.error);
-    const candidate = this.candidateVersion;
-    this.candidateVersion = null;
-    const candidateDescribesFailure =
-      candidate?.status === "missing" || candidate?.status === "error";
-    const observation: LiveFileObservation = candidateDescribesFailure
-      ? candidate
-      : { status: "error", cwd: input.target.cwd, path: input.target.path, error: message };
-    this.setSnapshot({ ...this.snapshot, observation, read: { status: "error", error: message } });
-    this.startQueuedRead();
-  }
-
-  private isActiveRead(generation: number, sequence: number): boolean {
-    return generation === this.generation && sequence === this.activeReadSequence;
-  }
-
-  private readPredatesLatestObservation(sequence: number): boolean {
-    return this.observedAfterReadSequence !== null && sequence <= this.observedAfterReadSequence;
-  }
-
-  private startQueuedRead(): void {
-    if (!this.refreshQueued) return;
-    this.startRead(this.takeQueuedRequested());
-  }
-
-  private takeQueuedRequested(): boolean {
-    const requested = this.requestedRefreshQueued;
-    this.refreshQueued = false;
-    this.requestedRefreshQueued = false;
-    return requested;
-  }
-
-  private setSnapshot(snapshot: LiveFileSnapshot): void {
-    if (snapshot === this.snapshot) return;
-    this.snapshot = snapshot;
-    for (const listener of this.listeners) listener();
-  }
-}
-
-function readyVersion(
-  target: LiveFileTarget,
-  file: FileReadResult,
-): Extract<FileVersion, { status: "ready" }> {
-  return {
-    status: "ready",
-    cwd: target.cwd,
-    path: target.path,
-    size: file.size,
-    modifiedAt: file.modifiedAt,
-    revision: file.revision,
-  };
-}
-
-function errorMessage(error: unknown): string {
-  return error instanceof Error ? error.message : String(error);
-}

packages/app/src/file-pane/pane.tsx

@@ -1,194 +1,27 @@
-import { Button } from "@/components/ui/button";
-import { LoadingSpinner } from "@/components/ui/loading-spinner";
-import React, { useCallback, useEffect, useMemo, useState, useSyncExternalStore } from "react";
-import type { DaemonClient } from "@getpaseo/client/internal/daemon-client";
+import { useEffect, useMemo, useState } from "react";
+import type { PluginFile, PluginFileTab } from "@getpaseo/plugin/client";
 import { Text, View } from "react-native";
-import { StyleSheet, withUnistyles } from "react-native-unistyles";
+import { StyleSheet } from "react-native-unistyles";
 import { useTranslation } from "react-i18next";
-import { useIsCompactFormFactor } from "@/constants/layout";
-import { useSessionStore, type ExplorerFile } from "@/stores/session-store";
-import { FilePanelPreview, resolveFilePreviewPanel, type FilePanel } from "@/file-panels";
-import { useAttachmentPreviewUrl } from "@/attachments/use-attachment-preview-url";
-import { getFileNameFromPath } from "@/attachments/utils";
-import { resolveFilePreviewReadTarget } from "@/file-explorer/preview-target";
-import type { WorkspaceFileLocation } from "@/workspace/file-open";
+import { Button } from "@/components/ui/button";
 import { useRetainedPanelActive } from "@/components/retained-panel";
+import { useFileHandle, useFileHandleSnapshot } from "@/file-panels/file";
+import { FilePanelLoading } from "@/file-panels/loading";
+import { FilePanelPicker, FilePanelView, useFilePanelChoice, type FilePanel } from "@/file-panels";
+import { resolveFilePreviewReadTarget } from "@/file-explorer/preview-target";
 import { useAppActivelyVisible } from "@/hooks/use-app-visible";
-import { isFileQueryEnabled } from "@/components/file-pane-enabled";
-import { isWeb } from "@/constants/platform";
-import { useAppSettings } from "@/hooks/use-settings";
-import { useLiveFile } from "./live-file/hook";
-import { useFilePreview } from "./preview-lifecycle/hook";
-import { resolveFilePreviewLifecycle } from "./preview-lifecycle/model";
-import { FilePanelBar } from "./bar";
-import { FileEditorModel, getFileConflictCallout, type FileConflictCallout } from "./editor/model";
-import { createFileObservationSource } from "./editor/observation-source";
-import { FileEditorView } from "./editor/view";
-import { FileSourceView } from "./source/view";
-import type { FileConflictAlertState } from "./conflict-alert";
-import type { LiveFileModel } from "./live-file/model";
-import { confirmDialog } from "@/utils/confirm-dialog";
 import { usePublishPanelInstanceAttributes } from "@/panels/panel-instance-attributes";
-import type { Theme } from "@/styles/theme";
-
-// CodeMirror and native source rendering consume appearance as props. Subscribe at the
-// rendering leaf so theme updates reconfigure it without replacing the editor/model.
-const sourceAppearance = (theme: Theme) => ({
-  theme: {
-    colorScheme: theme.colorScheme,
-    background: theme.colors.surface0,
-    foreground: theme.colors.foreground,
-    cursor: theme.colors.terminal.cursor,
-    foregroundMuted: theme.colors.foregroundMuted,
-    border: theme.colors.border,
-    selection: theme.colors.terminal.selectionBackground,
-    monoFont: theme.fontFamily.mono,
-    codeFontSize: theme.fontSize.code,
-    syntax: theme.colors.syntax,
-  },
-});
-const ThemedFileEditorView = withUnistyles(FileEditorView, sourceAppearance);
-const ThemedFileSourceView = withUnistyles(FileSourceView, sourceAppearance);
-
-const ThemedLoadingSpinner = withUnistyles(LoadingSpinner);
-const foregroundMutedColorMapping = (theme: Theme) => ({
-  color: theme.colors.foregroundMuted,
-});
-
-interface FilePreviewBodyProps {
-  panel: FilePanel | null;
-  preview: ExplorerFile | null;
-  mode?: "preview" | "source";
-  isLoading: boolean;
-  isMobile: boolean;
-  location: WorkspaceFileLocation;
-  navigationRevision: number;
-  imagePreviewUri: string | null;
-  workspaceRoot: string;
-  client: DaemonClient | null;
-  serverId: string;
-}
-
-type TextExplorerFile = ExplorerFile & { kind: "text" };
-
-function trimNonEmpty(value: string | null | undefined): string | null {
-  if (typeof value !== "string") {
-    return null;
-  }
-  const trimmed = value.trim();
-  return trimmed.length > 0 ? trimmed : null;
-}
-
-function formatFileSize({ size }: { size: number }): string {
-  if (size < 1024) {
-    return `${size} B`;
-  }
-  if (size < 1024 * 1024) {
-    return `${(size / 1024).toFixed(1)} KB`;
-  }
-  return `${(size / (1024 * 1024)).toFixed(1)} MB`;
-}
-
-function ReadonlySource({
-  preview,
-  filename,
-  location,
-  navigationRevision,
-}: {
-  preview: ExplorerFile;
-  filename: string;
-  location: WorkspaceFileLocation;
-  navigationRevision: number;
-}) {
-  const { t } = useTranslation();
-  return (
-    <ThemedFileSourceView
-      content={preview.content ?? ""}
-      filename={filename}
-      location={location}
-      navigationRevision={navigationRevision}
-      size={preview.size}
-      tooLargeMessage={t("panels.file.tooLargeToDisplay")}
-    />
-  );
-}
-
-function TooLargeSource({ size }: { size?: number }) {
-  const { t } = useTranslation();
-  return (
-    <View style={styles.centerState} testID="file-source-too-large">
-      <Text style={styles.emptyText}>{t("panels.file.tooLargeToDisplay")}</Text>
-      {size ? <Text style={styles.binaryMetaText}>{formatFileSize({ size })}</Text> : null}
-    </View>
-  );
-}
-
-function FilePreviewBody({
-  panel,
-  preview,
-  mode,
-  isLoading,
-  isMobile: _isMobile,
-  location,
-  navigationRevision,
-  imagePreviewUri,
-  workspaceRoot,
-  client,
-  serverId,
-}: FilePreviewBodyProps) {
-  const { t } = useTranslation();
-  const filePath = location.path;
-
-  if (isLoading && !preview) {
-    return (
-      <View style={styles.centerState} testID="file-preview-loading">
-        <ThemedLoadingSpinner size="small" uniProps={foregroundMutedColorMapping} />
-        <Text style={styles.loadingText}>{t("panels.file.loading")}</Text>
-      </View>
-    );
-  }
-
-  if (!preview) {
-    return (
-      <View style={styles.centerState} testID="file-preview-unsupported">
-        <Text style={styles.emptyText}>{t("panels.file.noPreview")}</Text>
-      </View>
-    );
-  }
-
-  const showSource = preview.kind === "text" && (Boolean(location.lineStart) || mode === "source");
-  if (panel && !showSource) {
-    return (
-      <FilePanelPreview
-        panel={panel}
-        content={preview.content ?? ""}
-        filePath={filePath}
-        workspaceRoot={workspaceRoot}
-        client={client}
-        serverId={serverId}
-        imagePreviewUri={imagePreviewUri}
-      />
-    );
-  }
-  if (preview.kind === "text") {
-    return (
-      <ReadonlySource
-        preview={preview}
-        filename={filePath}
-        location={location}
-        navigationRevision={navigationRevision}
-      />
-    );
-  }
-
-  return (
-    <View style={styles.centerState}>
-      <Text style={styles.emptyText}>{t("panels.file.binaryPreviewUnavailable")}</Text>
-      <Text style={styles.binaryMetaText}>{formatFileSize({ size: preview.size })}</Text>
-    </View>
-  );
-}
+import { useSessionStore } from "@/stores/session-store";
+import { buildAbsoluteExplorerPath } from "@/utils/explorer-paths";
+import { formatFileSize } from "@/utils/format-file-size";
+import type { WorkspaceFileLocation } from "@/workspace/file-open";
+import { FilePanelBar } from "./bar";
 
+/**
+ * The file tab: stats the file, picks its panel and mounts it. The panel reads, saves and shows
+ * its own loading; the tab only knows the file exists, its kind, and whether the panel has
+ * unsaved changes.
+ */
 export function FilePane({
   serverId,
   workspaceRoot,
@@ -201,417 +34,120 @@ export function FilePane({
   navigationRevision: number;
 }) {
   const { t } = useTranslation();
-  const { settings } = useAppSettings();
-  const isMobile = useIsCompactFormFactor();
-  const [previewMode, setPreviewMode] = useState<"preview" | "source">("preview");
-
-  const client = useSessionStore((state) => state.sessions[serverId]?.client ?? null);
-  // COMPAT(workspaceFileEditing): added in v0.2.0, remove after 2027-01-18 once daemon floor >= v0.2.0.
-  const supportsEditing = useSessionStore(
-    (state) => state.sessions[serverId]?.serverInfo?.features?.workspaceFileEditing === true,
+  const connected = useSessionStore((state) => Boolean(state.sessions[serverId]?.client));
+  const root = workspaceRoot.trim();
+  const path = location.path.trim();
+  const target = useMemo(
+    () => (path ? resolveFilePreviewReadTarget({ path, workspaceRoot: root }) : null),
+    [path, root],
   );
-  const normalizedWorkspaceRoot = useMemo(() => workspaceRoot.trim(), [workspaceRoot]);
-  const normalizedFilePath = useMemo(() => trimNonEmpty(location.path), [location.path]);
-  const readTarget = useMemo(
-    () =>
-      normalizedFilePath
-        ? resolveFilePreviewReadTarget({
-            path: normalizedFilePath,
-            workspaceRoot: normalizedWorkspaceRoot,
-          })
-        : null,
-    [normalizedFilePath, normalizedWorkspaceRoot],
+  const absolutePath = useMemo(
+    () => buildAbsoluteExplorerPath({ workspaceRoot: root, entryPath: path }),
+    [path, root],
   );
-
-  // Re-read the file when this pane becomes visible again (#445). `isActive`
-  // covers tab switches; active app visibility covers backgrounding and returning
-  // from another window after an external edit. The gate lives in isFileQueryEnabled.
+  // A hidden tab or a backgrounded app stops observing; observing again reports what changed.
   const isActive = useRetainedPanelActive();
   const isAppVisible = useAppActivelyVisible();
-  const enabled = isFileQueryEnabled({
-    hasReadTarget: Boolean(client && readTarget),
-    isTabActive: isActive,
-    isAppVisible,
+  const handle = useFileHandle({
+    serverId,
+    target,
+    absolutePath,
+    observing: isActive && isAppVisible,
   });
-  const liveFile = useLiveFile({
-    client,
-    cwd: readTarget?.cwd ?? null,
-    path: readTarget?.path ?? null,
-    enabled,
-    liveUpdates: supportsEditing,
-  });
-
-  const targetKey = readTarget ? `${readTarget.cwd}:${readTarget.path}` : null;
-  const previewLifecycle = useFilePreview({
+  const snapshot = useFileHandleSnapshot(handle);
+  const targetKey = target ? `${target.cwd}:${target.path}` : null;
+  const { panel, choice } = useFilePanelChoice({
+    serverId,
     targetKey,
-    liveFileSnapshot: liveFile.snapshot,
+    path,
+    fileKind: snapshot.status === "ready" ? snapshot.kind : null,
+    presentable: isActive,
+    lineNavigation: location.lineStart ? navigationRevision : null,
   });
-
-  useEffect(() => setPreviewMode("preview"), [targetKey]);
-
-  const { file: preview, imageAttachment } = resolveFilePreviewLifecycle(previewLifecycle);
-  const imagePreviewUri = useAttachmentPreviewUrl(imageAttachment);
-  const panel = resolveFilePreviewPanel({
-    preview,
-    path: location.path,
-    associations: settings.filePanelAssociations,
-  });
-  const isRenderable = preview?.kind === "text" && panel !== null;
-  const editable = isEditableTextFile({
-    preview,
-    supportsEditing,
-  });
-  const canTogglePreviewMode = isRenderable && !location.lineStart;
-  const lineCount =
-    preview?.kind === "text" ? (preview.content ?? "").split("\n").length : undefined;
-  const errorMessage = previewLifecycle.status === "error" ? previewLifecycle.message : null;
-  const isLoading =
-    previewLifecycle.status === "initial" ||
-    previewLifecycle.status === "read_pending" ||
-    previewLifecycle.status === "preparing";
-
-  return (
-    <FilePanePresentation
-      panel={panel}
-      serverId={serverId}
-      workspaceRoot={normalizedWorkspaceRoot}
-      client={client}
-      readTarget={readTarget}
-      preview={preview}
-      liveFile={liveFile.model}
-      onRetryRead={liveFile.refresh}
-      retryingRead={liveFile.isRetrying}
-      retryLabel={t("common.actions.retry")}
-      filename={getFileNameFromPath(location.path) ?? location.path}
-      previewMode={canTogglePreviewMode ? previewMode : undefined}
-      onPreviewModeChange={canTogglePreviewMode ? setPreviewMode : undefined}
-      lineCount={lineCount}
-      editable={editable}
-      disconnectedMessage={t("workspace.terminal.hostDisconnected")}
-      errorMessage={errorMessage}
-      isLoading={isLoading}
-      isMobile={isMobile}
-      location={location}
-      navigationRevision={navigationRevision}
-      imagePreviewUri={imagePreviewUri}
-    />
+  const [modified, setModified] = useState(false);
+  usePublishPanelInstanceAttributes({ modified, suspendPendingSave: handle?.holdWrites });
+  const panelLocation = useMemo(
+    () => ({
+      lineStart: location.lineStart,
+      lineEnd: location.lineEnd,
+      revision: navigationRevision,
+    }),
+    [location.lineEnd, location.lineStart, navigationRevision],
   );
-}
-
-function isEditableTextFile(input: {
-  preview: ExplorerFile | null;
-  supportsEditing: boolean;
-}): boolean {
-  return Boolean(
-    isWeb &&
-    input.supportsEditing &&
-    input.preview?.kind === "text" &&
-    input.preview.size <= 1024 * 1024,
+  const panelTarget = useMemo(
+    () => ({ serverId, workspaceRoot: root, path }),
+    [path, root, serverId],
   );
-}
 
-function FilePanePresentation({
-  panel,
-  serverId,
-  workspaceRoot,
-  client,
-  readTarget,
-  preview,
-  liveFile,
-  onRetryRead,
-  retryingRead,
-  retryLabel,
-  filename,
-  previewMode,
-  onPreviewModeChange,
-  lineCount,
-  editable,
-  disconnectedMessage,
-  errorMessage,
-  isLoading,
-  isMobile,
-  location,
-  navigationRevision,
-  imagePreviewUri,
-}: {
-  panel: FilePanel | null;
-  serverId: string;
-  workspaceRoot: string;
-  client: DaemonClient | null;
-  readTarget: { cwd: string; path: string } | null;
-  preview: ExplorerFile | null;
-  liveFile: LiveFileModel;
-  onRetryRead: () => void;
-  retryingRead: boolean;
-  retryLabel: string;
-  filename: string;
-  previewMode?: "preview" | "source";
-  onPreviewModeChange?: (mode: "preview" | "source") => void;
-  lineCount?: number;
-  editable: boolean;
-  disconnectedMessage: string;
-  errorMessage: string | null;
-  isLoading: boolean;
-  isMobile: boolean;
-  location: WorkspaceFileLocation;
-  navigationRevision: number;
-  imagePreviewUri: string | null;
-}) {
-  if (!client && readTarget) {
+  let body;
+  if (!connected && target) {
+    body = <Text style={styles.errorText}>{t("workspace.terminal.hostDisconnected")}</Text>;
+  } else if (!handle || snapshot.status === "loading") {
     return (
       <View style={styles.container} testID="workspace-file-pane">
-        <View style={styles.centerState}>
-          <Text style={styles.errorText}>{disconnectedMessage}</Text>
-        </View>
+        <FilePanelLoading />
       </View>
     );
-  }
-
-  if (editable && client && readTarget && preview?.kind === "text") {
-    return (
-      <EditableFilePane
-        panel={panel}
-        key={`${serverId}:${readTarget.cwd}:${readTarget.path}`}
-        serverId={serverId}
-        workspaceRoot={workspaceRoot}
-        client={client}
-        cwd={readTarget.cwd}
-        path={readTarget.path}
-        preview={preview as TextExplorerFile}
-        liveFile={liveFile}
-        onRetryRead={onRetryRead}
-        retryingRead={retryingRead}
-        filename={filename}
-        mode={previewMode}
-        onModeChange={onPreviewModeChange}
-        isLoading={isLoading}
-        isMobile={isMobile}
-        location={location}
-        navigationRevision={navigationRevision}
-      />
+  } else if (snapshot.status === "missing" || snapshot.status === "error") {
+    body = (
+      <>
+        <Text style={styles.errorText}>
+          {snapshot.status === "error" ? snapshot.error : t("panels.file.notFound")}
+        </Text>
+        <Button variant="outline" size="sm" onPress={handle.retry}>
+          {t("common.actions.retry")}
+        </Button>
+      </>
     );
-  }
-
-  if (errorMessage) {
-    if (errorMessage === "File is too large to display") {
-      return (
-        <View style={styles.container} testID="workspace-file-pane">
-          <TooLargeSource />
-        </View>
-      );
-    }
+  } else if (!panel) {
+    body = (
+      <>
+        <Text style={styles.mutedText}>{t("panels.file.binaryPreviewUnavailable")}</Text>
+        <Text style={styles.mutedText}>{formatFileSize(snapshot.size)}</Text>
+      </>
+    );
+  } else {
     return (
       <View style={styles.container} testID="workspace-file-pane">
-        <View style={styles.centerState}>
-          <Text style={styles.errorText}>{errorMessage}</Text>
-          <Button variant="outline" size="sm" onPress={onRetryRead} loading={retryingRead}>
-            {retryLabel}
-          </Button>
-        </View>
-      </View>
-    );
-  }
-
-  return (
-    <View style={styles.container} testID="workspace-file-pane">
-      {preview ? (
-        <FilePanelBar
-          size={preview.size}
-          lineCount={lineCount}
-          mode={previewMode}
-          onModeChange={onPreviewModeChange}
-        />
-      ) : null}
-      <FilePreviewBody
-        panel={panel}
-        preview={preview}
-        mode={previewMode}
-        isLoading={isLoading}
-        isMobile={isMobile}
-        location={location}
-        navigationRevision={navigationRevision}
-        imagePreviewUri={imagePreviewUri}
-        workspaceRoot={workspaceRoot}
-        client={client}
-        serverId={serverId}
-      />
-    </View>
-  );
-}
-
-function EditableFilePane({
-  panel,
-  serverId,
-  workspaceRoot,
-  client,
-  cwd,
-  path,
-  preview,
-  liveFile,
-  onRetryRead,
-  retryingRead,
-  filename,
-  mode,
-  onModeChange,
-  isLoading,
-  isMobile,
-  location,
-  navigationRevision,
-}: {
-  panel: FilePanel | null;
-  serverId: string;
-  workspaceRoot: string;
-  client: DaemonClient;
-  cwd: string;
-  path: string;
-  preview: TextExplorerFile;
-  liveFile: LiveFileModel;
-  onRetryRead: () => void;
-  retryingRead: boolean;
-  filename: string;
-  mode?: "preview" | "source";
-  onModeChange?: (mode: "preview" | "source") => void;
-  isLoading: boolean;
-  isMobile: boolean;
-  location: WorkspaceFileLocation;
-  navigationRevision: number;
-}) {
-  const { settings } = useAppSettings();
-  const { t } = useTranslation();
-  const [cursor, setCursor] = useState({ line: 1, column: 1 });
-  const [vimMode, setVimMode] = useState<string | null>(settings.vimKeybindings ? "NORMAL" : null);
-  const session = useMemo(
-    () => ({
-      write(input: { content: string; expectedModifiedAt: string; expectedRevision?: string }) {
-        return client.writeFile({ cwd, path, ...input });
-      },
-    }),
-    [client, cwd, path],
-  );
-  const [model] = useState(() => {
-    return new FileEditorModel({
-      file: {
-        content: preview.content ?? "",
-        hasBom: preview.hasBom,
-        version: {
-          status: "ready",
-          cwd,
-          path,
-          size: preview.size,
-          modifiedAt: preview.modifiedAt,
-          revision: preview.revision,
-        },
-      },
-      session,
-    });
-  });
-  useEffect(() => {
-    const source = createFileObservationSource(liveFile);
-    model.connectFileObservations(source);
-    return () => model.disconnectFileObservations();
-  }, [liveFile, model]);
-  const snapshot = useSyncExternalStore(model.subscribe, model.getSnapshot, model.getSnapshot);
-  const suspendPendingSave = useCallback(() => model.suspendAutosave(), [model]);
-  usePublishPanelInstanceAttributes({ modified: snapshot.modified, suspendPendingSave });
-  useEffect(() => () => model.dispose(), [model]);
-
-  const handleReload = useCallback(() => {
-    if (!snapshot.modified) {
-      void model.reload();
-      return;
-    }
-    void (async () => {
-      const confirmed = await confirmDialog({
-        title: t("panels.file.editor.reloadTitle"),
-        message: t("panels.file.editor.reloadMessage"),
-        confirmLabel: t("panels.file.editor.reload"),
-        destructive: true,
-      });
-      if (confirmed) void model.reload();
-    })();
-  }, [model, snapshot.modified, t]);
-  const handleOverwrite = useCallback(() => void model.overwrite(), [model]);
-  const conflict = fileConflictAlertState({
-    callout: getFileConflictCallout(snapshot),
-    onOverwrite: handleOverwrite,
-    onReload: handleReload,
-    onRetry: onRetryRead,
-    retrying: retryingRead,
-  });
-  const handleVimModeChange = useCallback((nextMode: string | null) => setVimMode(nextMode), []);
-  const renderedPreview = useMemo<ExplorerFile>(
-    () => ({
-      ...preview,
-      content: snapshot.content,
-      size: snapshot.version.status === "ready" ? snapshot.version.size : preview.size,
-      modifiedAt:
-        snapshot.version.status === "ready" ? snapshot.version.modifiedAt : preview.modifiedAt,
-    }),
-    [preview, snapshot.content, snapshot.version],
-  );
-  const showSource = mode !== "preview";
-
-  return (
-    <View style={styles.container} testID="workspace-file-pane">
-      <FilePanelBar
-        size={
-          snapshot.observedVersion.status === "ready" ? snapshot.observedVersion.size : preview.size
-        }
-        lineCount={snapshot.content.split("\n").length}
-        editorStatus={snapshot.status}
-        cursor={showSource ? cursor : undefined}
-        vimMode={showSource ? vimMode : null}
-        conflict={conflict}
-        mode={mode}
-        onModeChange={onModeChange}
-      />
-      {showSource ? (
-        <ThemedFileEditorView
-          model={model}
-          filename={filename}
-          location={location}
-          navigationRevision={navigationRevision}
-          vimEnabled={settings.vimKeybindings}
-          onCursorChange={setCursor}
-          onVimModeChange={handleVimModeChange}
-        />
-      ) : (
-        <FilePreviewBody
+        <FilePanelPicker choice={choice} />
+        <FilePanelBar choice={choice} modified={modified} />
+        <MountedFilePanel
+          key={`${panel.id}:${targetKey}`}
           panel={panel}
-          preview={renderedPreview}
-          mode={mode}
-          isLoading={isLoading}
-          isMobile={isMobile}
-          location={location}
-          navigationRevision={navigationRevision}
-          imagePreviewUri={null}
-          workspaceRoot={workspaceRoot}
-          client={client}
-          serverId={serverId}
+          file={handle.file}
+          location={panelLocation}
+          target={panelTarget}
+          onModifiedChange={setModified}
         />
-      )}
+      </View>
+    );
+  }
+  return (
+    <View style={styles.container} testID="workspace-file-pane">
+      <View style={styles.centerState}>{body}</View>
     </View>
   );
 }
 
-function fileConflictAlertState(input: {
-  callout: FileConflictCallout | null;
-  onOverwrite(): void;
-  onReload(): void;
-  onRetry(): void;
-  retrying: boolean;
-}): FileConflictAlertState | undefined {
-  if (!input.callout) return undefined;
-  if (input.callout.kind === "deleted") return { kind: "deleted" };
-  if (input.callout.kind === "checkFailed") {
-    return { kind: "checkFailed", retrying: input.retrying, onRetry: input.onRetry };
-  }
-  return {
-    kind: "changed",
-    canOverwrite: input.callout.canOverwrite,
-    onReload: input.onReload,
-    onOverwrite: input.onOverwrite,
-  };
+/** One panel mount. Its tab reports unsaved changes until the panel unmounts. */
+function MountedFilePanel({
+  panel,
+  file,
+  location,
+  target,
+  onModifiedChange,
+}: {
+  panel: FilePanel;
+  file: PluginFile;
+  location: { lineStart?: number; lineEnd?: number; revision: number };
+  target: { serverId: string; workspaceRoot: string; path: string };
+  onModifiedChange: (modified: boolean) => void;
+}) {
+  const [tab] = useState<PluginFileTab>(() => ({
+    setModified: (modified) => onModifiedChange(modified),
+  }));
+  useEffect(() => () => onModifiedChange(false), [onModifiedChange]);
+  return <FilePanelView panel={panel} file={file} tab={tab} location={location} target={target} />;
 }
 
 const styles = StyleSheet.create((theme) => ({
@@ -627,24 +163,14 @@ const styles = StyleSheet.create((theme) => ({
     gap: theme.spacing[3],
     padding: theme.spacing[4],
   },
-  loadingText: {
-    marginTop: theme.spacing[2],
-    color: theme.colors.foregroundMuted,
-    fontSize: theme.fontSize.base,
-  },
   errorText: {
     color: theme.colors.destructive,
     fontSize: theme.fontSize.base,
     textAlign: "center",
   },
-  emptyText: {
+  mutedText: {
     color: theme.colors.foregroundMuted,
     fontSize: theme.fontSize.base,
     textAlign: "center",
   },
-  binaryMetaText: {
-    marginTop: theme.spacing[2],
-    color: theme.colors.foregroundMuted,
-    fontSize: theme.fontSize.base,
-  },
 }));

packages/app/src/file-pane/preview-lifecycle/hook.ts

@@ -1,23 +0,0 @@
-import { useEffect, useState, useSyncExternalStore } from "react";
-import type { LiveFileSnapshot } from "../live-file/model";
-import {
-  createFilePanePreview,
-  FilePreviewLifecycleModel,
-  type FilePreviewLifecycleSnapshot,
-} from "./model";
-
-/** Bridges the raw-file owner to the preview preparation owner. */
-export function useFilePreview(input: {
-  targetKey: string | null;
-  liveFileSnapshot: LiveFileSnapshot;
-}): FilePreviewLifecycleSnapshot {
-  const [model] = useState(() => new FilePreviewLifecycleModel(createFilePanePreview));
-  const snapshot = useSyncExternalStore(model.subscribe, model.getSnapshot, model.getSnapshot);
-  const { targetKey, liveFileSnapshot } = input;
-
-  useEffect(() => {
-    model.setSource({ targetKey, liveFileSnapshot });
-  }, [liveFileSnapshot, model, targetKey]);
-
-  return snapshot;
-}

packages/app/src/file-pane/preview-lifecycle/model.test.ts

@@ -1,157 +0,0 @@
-import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
-import type { LiveFileSnapshot } from "../live-file/model";
-import { describe, expect, it } from "vitest";
-import {
-  FilePreviewLifecycleModel,
-  type FilePanePreview,
-  type FilePreviewLifecycleSnapshot,
-} from "./model";
-
-function previewFile(content: string) {
-  return {
-    kind: "text" as const,
-    path: "file.ts",
-    size: 7,
-    encoding: "utf-8" as const,
-    hasBom: false,
-    modifiedAt: "2026-08-20T00:00:00.000Z",
-    content,
-  };
-}
-
-interface Deferred<T> {
-  promise: Promise<T>;
-  resolve(value: T): void;
-  reject(error: Error): void;
-}
-
-function deferred<T>(): Deferred<T> {
-  let resolve!: (value: T) => void;
-  let reject!: (error: Error) => void;
-  const promise = new Promise<T>((onResolve, onReject) => {
-    resolve = onResolve;
-    reject = onReject;
-  });
-  return { promise, resolve, reject };
-}
-
-function file(revision = "revision-1", path = "file.ts"): FileReadResult {
-  return {
-    bytes: new TextEncoder().encode("preview"),
-    mime: "text/plain",
-    size: 7,
-    path,
-    kind: "text",
-    modifiedAt: "2026-08-20T00:00:00.000Z",
-    revision,
-  };
-}
-
-function pending(): LiveFileSnapshot {
-  return { observation: null, read: { status: "pending", requested: false } };
-}
-
-function completed(rawFile: FileReadResult): LiveFileSnapshot {
-  return {
-    observation: {
-      status: "ready",
-      file: rawFile,
-      version: {
-        status: "ready",
-        cwd: "/workspace",
-        path: rawFile.path,
-        size: rawFile.size,
-        modifiedAt: rawFile.modifiedAt,
-        revision: rawFile.revision,
-      },
-    },
-    read: { status: "idle" },
-  };
-}
-
-function source(
-  targetKey: string,
-  snapshot: LiveFileSnapshot,
-): {
-  targetKey: string;
-  liveFileSnapshot: LiveFileSnapshot;
-} {
-  return { targetKey, liveFileSnapshot: snapshot };
-}
-
-describe("FilePreviewLifecycleModel", () => {
-  it("represents pending raw reads, preparation, ready previews, unsupported files, and conversion failures", async () => {
-    const first = deferred<FilePanePreview | null>();
-    const second = deferred<FilePanePreview | null>();
-    const third = deferred<FilePanePreview | null>();
-    const preparations = [first, second, third];
-    const model = new FilePreviewLifecycleModel(() => preparations.shift()!.promise);
-    const preview: FilePanePreview = {
-      file: previewFile("preview"),
-      imageAttachment: null,
-    };
-
-    model.setSource(source("/workspace:file.ts", pending()));
-    expect(model.getSnapshot()).toEqual({ status: "read_pending" });
-
-    model.setSource(source("/workspace:file.ts", completed(file("one"))));
-    expect(model.getSnapshot()).toEqual({ status: "preparing" });
-    first.resolve(preview);
-    await expectSnapshot(model, { status: "ready", preview });
-
-    model.setSource(source("/workspace:file.ts", pending()));
-    expect(model.getSnapshot()).toEqual({ status: "read_pending", preview });
-
-    model.setSource(
-      source("/workspace:file.ts", {
-        observation: {
-          status: "error",
-          cwd: "/workspace",
-          path: "file.ts",
-          error: "Requested path is not a file",
-        },
-        read: { status: "pending", requested: true },
-      }),
-    );
-    expect(model.getSnapshot()).toEqual({ status: "read_pending", preview });
-
-    model.setSource(source("/workspace:file.ts", completed(file("two"))));
-    expect(model.getSnapshot()).toEqual({ status: "preparing", preview });
-    second.resolve(null);
-    await expectSnapshot(model, { status: "unsupported" });
-
-    model.setSource(source("/workspace:file.ts", completed(file("three"))));
-    expect(model.getSnapshot()).toEqual({ status: "preparing" });
-    third.reject(new Error("attachment failed"));
-    await expectSnapshot(model, { status: "error", message: "attachment failed" });
-  });
-
-  it("does not publish a stale conversion after retargeting", async () => {
-    const first = deferred<FilePanePreview | null>();
-    const second = deferred<FilePanePreview | null>();
-    const model = new FilePreviewLifecycleModel((rawFile) =>
-      rawFile.revision === "one" ? first.promise : second.promise,
-    );
-    const nextPreview: FilePanePreview = {
-      file: previewFile("two"),
-      imageAttachment: null,
-    };
-
-    model.setSource(source("/workspace:file.ts", completed(file("one"))));
-    model.setSource(source("/workspace:second.ts", completed(file("two", "second.ts"))));
-    first.resolve({ file: previewFile("one"), imageAttachment: null });
-    await Promise.resolve();
-    expect(model.getSnapshot()).toEqual({ status: "preparing" });
-
-    second.resolve(nextPreview);
-    await expectSnapshot(model, { status: "ready", preview: nextPreview });
-  });
-});
-
-async function expectSnapshot(
-  model: FilePreviewLifecycleModel,
-  expected: FilePreviewLifecycleSnapshot,
-): Promise<void> {
-  await new Promise<void>((resolve) => queueMicrotask(resolve));
-  expect(model.getSnapshot()).toEqual(expected);
-}

packages/app/src/file-pane/preview-lifecycle/model.ts

@@ -1,190 +0,0 @@
-import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
-import type { AttachmentMetadata } from "@/attachments/types";
-import { persistAttachmentFromBytes } from "@/attachments/service";
-import { createPreviewAttachmentId, getFileNameFromPath } from "@/attachments/utils";
-import { explorerFileFromReadResult } from "@/file-explorer/read-result";
-import type { ExplorerFile } from "@/stores/session-store";
-import type { LiveFileSnapshot } from "../live-file/model";
-
-export interface FilePanePreview {
-  file: ExplorerFile;
-  imageAttachment: AttachmentMetadata | null;
-}
-
-export type FilePreviewLifecycleSnapshot =
-  | { status: "initial" }
-  | { status: "read_pending"; preview?: FilePanePreview }
-  | { status: "preparing"; preview?: FilePanePreview }
-  | { status: "ready"; preview: FilePanePreview }
-  | { status: "error"; message: string; preview?: FilePanePreview }
-  | { status: "unsupported" };
-
-const initialSnapshot: FilePreviewLifecycleSnapshot = { status: "initial" };
-
-/** Converts a completed raw read into the preview resources consumed by FilePane. */
-export async function createFilePanePreview(file: FileReadResult): Promise<FilePanePreview | null> {
-  const explorerFile = explorerFileFromReadResult(file);
-  if (file.kind !== "image") {
-    return { file: explorerFile, imageAttachment: null };
-  }
-
-  const imageAttachment = await persistAttachmentFromBytes({
-    id: createPreviewAttachmentId({
-      mimeType: file.mime,
-      path: file.path,
-      size: file.size,
-      modifiedAt: file.modifiedAt,
-      contentLength: file.bytes.byteLength,
-    }),
-    bytes: file.bytes,
-    mimeType: file.mime,
-    fileName: getFileNameFromPath(file.path),
-  });
-
-  return { file: explorerFile, imageAttachment };
-}
-
-/** Owns conversion after LiveFileModel has produced a raw file snapshot. */
-export class FilePreviewLifecycleModel {
-  private readonly listeners = new Set<() => void>();
-  private snapshot: FilePreviewLifecycleSnapshot = initialSnapshot;
-  private generation = 0;
-  private preparedSourceKey: string | null = null;
-  private targetKey: string | null = null;
-
-  constructor(
-    private readonly prepare: (file: FileReadResult) => Promise<FilePanePreview | null>,
-  ) {}
-
-  subscribe = (listener: () => void): (() => void) => {
-    this.listeners.add(listener);
-    return () => this.listeners.delete(listener);
-  };
-
-  getSnapshot = (): FilePreviewLifecycleSnapshot => this.snapshot;
-
-  setSource(input: { targetKey: string | null; liveFileSnapshot: LiveFileSnapshot }): void {
-    const targetChanged = input.targetKey !== this.targetKey;
-    const retainedPreview = targetChanged ? undefined : filePreviewFromLifecycle(this.snapshot);
-    if (targetChanged) {
-      this.targetKey = input.targetKey;
-      this.preparedSourceKey = null;
-      this.generation += 1;
-    }
-
-    const source = getReadySource(input);
-    if (source) {
-      if (source.key === this.preparedSourceKey) {
-        return;
-      }
-      this.preparedSourceKey = source.key;
-      const generation = ++this.generation;
-      this.setSnapshot({
-        status: "preparing",
-        ...(retainedPreview ? { preview: retainedPreview } : {}),
-      });
-      void this.prepareSource({ file: source.file, generation, retainedPreview });
-      return;
-    }
-
-    const nextSnapshot = getNonReadySnapshot(input.liveFileSnapshot);
-    if (nextSnapshot.status === "initial" && retainedPreview) {
-      return;
-    }
-    const retainedSnapshot = retainedPreview
-      ? { ...nextSnapshot, preview: retainedPreview }
-      : nextSnapshot;
-    if (sameNonReadyState(this.snapshot, retainedSnapshot)) {
-      return;
-    }
-    this.preparedSourceKey = null;
-    this.generation += 1;
-    this.setSnapshot(retainedSnapshot);
-  }
-
-  private setSnapshot(snapshot: FilePreviewLifecycleSnapshot): void {
-    this.snapshot = snapshot;
-    for (const listener of this.listeners) listener();
-  }
-
-  private async prepareSource(input: {
-    file: FileReadResult;
-    generation: number;
-    retainedPreview?: FilePanePreview;
-  }): Promise<void> {
-    try {
-      const preview = await this.prepare(input.file);
-      if (input.generation !== this.generation) return;
-      this.setSnapshot(preview ? { status: "ready", preview } : { status: "unsupported" });
-    } catch (error) {
-      if (input.generation !== this.generation) return;
-      this.setSnapshot({
-        status: "error",
-        message: errorMessage(error),
-        ...(input.retainedPreview ? { preview: input.retainedPreview } : {}),
-      });
-    }
-  }
-}
-
-export function filePreviewFromLifecycle(
-  snapshot: FilePreviewLifecycleSnapshot,
-): FilePanePreview | undefined {
-  return "preview" in snapshot ? snapshot.preview : undefined;
-}
-
-export function resolveFilePreviewLifecycle(snapshot: FilePreviewLifecycleSnapshot): {
-  file: ExplorerFile | null;
-  imageAttachment: AttachmentMetadata | null;
-} {
-  const preview = filePreviewFromLifecycle(snapshot);
-  return preview ?? { file: null, imageAttachment: null };
-}
-
-function getReadySource(input: {
-  targetKey: string | null;
-  liveFileSnapshot: LiveFileSnapshot;
-}): { key: string; file: FileReadResult } | null {
-  const observation = input.liveFileSnapshot.observation;
-  if (!input.targetKey || observation?.status !== "ready") {
-    return null;
-  }
-  const { version } = observation;
-  if (input.targetKey !== `${version.cwd}:${version.path}`) {
-    return null;
-  }
-  return {
-    key: `${input.targetKey}:${version.revision ?? version.modifiedAt}:${version.size}`,
-    file: observation.file,
-  };
-}
-
-function getNonReadySnapshot(snapshot: LiveFileSnapshot): FilePreviewLifecycleSnapshot {
-  if (snapshot.read.status === "error") {
-    return { status: "error", message: snapshot.read.error };
-  }
-  if (snapshot.read.status === "pending") {
-    return { status: "read_pending" };
-  }
-  if (snapshot.observation?.status === "error") {
-    return { status: "error", message: snapshot.observation.error };
-  }
-  if (snapshot.observation?.status === "missing") {
-    return { status: "error", message: "File not found" };
-  }
-  return initialSnapshot;
-}
-
-function sameNonReadyState(
-  current: FilePreviewLifecycleSnapshot,
-  next: FilePreviewLifecycleSnapshot,
-): boolean {
-  if (current.status !== next.status) {
-    return false;
-  }
-  return current.status !== "error" || next.status !== "error" || current.message === next.message;
-}
-
-function errorMessage(error: unknown): string {
-  return error instanceof Error ? error.message : "Failed to prepare preview";
-}

packages/app/src/file-pane/source/view.native.tsx

@@ -1,141 +0,0 @@
-import { useEffect, useMemo, useRef } from "react";
-import { FlatList, Text, View, type ListRenderItem } from "react-native";
-import { StyleSheet } from "react-native-unistyles";
-import { highlightCode, type HighlightToken } from "@getpaseo/highlight";
-import { syntaxTokenStyleFor } from "@/styles/syntax-token-styles";
-import type { WorkspaceFileLocation } from "@/workspace/file-open";
-import type { EditorVisualTheme } from "../editor/extensions.web";
-import { selectSourcePresentation } from "./presentation";
-
-interface FileSourceViewProps {
-  content: string;
-  filename: string;
-  location: WorkspaceFileLocation;
-  navigationRevision: number;
-  size: number;
-  theme: EditorVisualTheme;
-  tooLargeMessage: string;
-}
-
-interface SourceLine {
-  number: number;
-  tokens: HighlightToken[];
-}
-
-export function FileSourceView({
-  content,
-  filename,
-  location,
-  navigationRevision,
-  size,
-  tooLargeMessage,
-}: FileSourceViewProps) {
-  const presentation = selectSourcePresentation({ size, platform: "native" });
-  if (presentation === "unsupported") {
-    return (
-      <View style={styles.unsupported} testID="file-source-too-large">
-        <Text style={styles.unsupportedText}>{tooLargeMessage}</Text>
-      </View>
-    );
-  }
-  return (
-    <VirtualizedSource
-      content={content}
-      filename={filename}
-      location={location}
-      navigationRevision={navigationRevision}
-      presentation={presentation}
-    />
-  );
-}
-
-function VirtualizedSource({
-  content,
-  filename,
-  location,
-  navigationRevision,
-  presentation,
-}: Omit<FileSourceViewProps, "size" | "theme" | "tooLargeMessage"> & {
-  presentation: "highlighted" | "plain";
-}) {
-  const listRef = useRef<FlatList<SourceLine>>(null);
-  const lines = useMemo(() => {
-    if (presentation === "highlighted")
-      return highlightCode(content, filename).map((tokens, index) => ({
-        number: index + 1,
-        tokens,
-      }));
-    return content
-      .split("\n")
-      .map((text, index) => ({ number: index + 1, tokens: [{ text, style: null }] }));
-  }, [content, filename, presentation]);
-  useEffect(() => {
-    if (!location.lineStart) return;
-    listRef.current?.scrollToIndex({
-      index: Math.min(location.lineStart - 1, lines.length - 1),
-      animated: false,
-      viewPosition: 0.5,
-    });
-  }, [lines.length, location.lineStart, navigationRevision]);
-  return (
-    <FlatList
-      ref={listRef}
-      data={lines}
-      keyExtractor={sourceLineKey}
-      initialNumToRender={24}
-      windowSize={9}
-      getItemLayout={sourceLineLayout}
-      renderItem={renderSourceLine}
-    />
-  );
-}
-
-function SourceLineView({ line }: { line: SourceLine }) {
-  return (
-    <View style={styles.line}>
-      <Text style={styles.gutter}>{line.number}</Text>
-      <Text selectable style={styles.text}>
-        {line.tokens.map((token) => (
-          <Text key={`${token.style}:${token.text}`} style={syntaxTokenStyleFor(token.style)}>
-            {token.text}
-          </Text>
-        ))}
-      </Text>
-    </View>
-  );
-}
-
-function sourceLineKey(line: SourceLine): string {
-  return String(line.number);
-}
-
-function sourceLineLayout(_data: ArrayLike<SourceLine> | null | undefined, index: number) {
-  return { length: 20, offset: index * 20, index };
-}
-
-const renderSourceLine: ListRenderItem<SourceLine> = ({ item }) => <SourceLineView line={item} />;
-
-const styles = StyleSheet.create((theme) => ({
-  unsupported: {
-    flex: 1,
-    alignItems: "center",
-    justifyContent: "center",
-    padding: theme.spacing[4],
-  },
-  unsupportedText: { color: theme.colors.foregroundMuted, textAlign: "center" },
-  line: { flexDirection: "row", minHeight: theme.fontSize.code * 1.45 },
-  gutter: {
-    width: 56,
-    paddingRight: theme.spacing[3],
-    textAlign: "right",
-    color: theme.colors.foregroundMuted,
-    fontFamily: theme.fontFamily.mono,
-    fontSize: theme.fontSize.code,
-  },
-  text: {
-    flex: 1,
-    fontFamily: theme.fontFamily.mono,
-    fontSize: theme.fontSize.code,
-    lineHeight: theme.fontSize.code * 1.45,
-  },
-}));

packages/app/src/file-panels/associations.ts

@@ -0,0 +1,34 @@
+import { useCallback } from "react";
+import { useAppSettings } from "@/hooks/use-settings";
+
+export interface FilePanelAssociations {
+  /** Selector key (`ext:md`, `name:Dockerfile`) → panel id, device-wide. */
+  associations: Readonly<Record<string, string>>;
+  /** Writes the association for a selector key, or forgets it with null. */
+  remember(selectorKey: string, panelId: string | null): void;
+}
+
+/** The one reader and writer of the device's file panel associations. */
+export function useFilePanelAssociations(): FilePanelAssociations {
+  const { settings, updateSettings } = useAppSettings();
+  const remember = useCallback(
+    (selectorKey: string, panelId: string | null) => {
+      void updateSettings((current) => ({
+        filePanelAssociations: withAssociation(current.filePanelAssociations, selectorKey, panelId),
+      }));
+    },
+    [updateSettings],
+  );
+  return { associations: settings.filePanelAssociations, remember };
+}
+
+function withAssociation(
+  associations: Readonly<Record<string, string>>,
+  selectorKey: string,
+  panelId: string | null,
+): Record<string, string> {
+  const next = { ...associations };
+  if (panelId === null) delete next[selectorKey];
+  else next[selectorKey] = panelId;
+  return next;
+}

packages/app/src/file-panels/builtin.tsx

@@ -1,92 +1,94 @@
-import type { DaemonClient } from "@getpaseo/client/internal/daemon-client";
+import { useFileText, useFileUrl } from "@getpaseo/plugin/client";
+import { useCallback, useState } from "react";
 import { ScrollView, Text, View } from "react-native";
-import { StyleSheet, withUnistyles } from "react-native-unistyles";
-import { useTranslation } from "react-i18next";
-import { LoadingSpinner } from "@/components/ui/loading-spinner";
+import { StyleSheet } from "react-native-unistyles";
 import { ZoomableImage } from "@/components/zoomable-viewport/image";
-import type { Theme } from "@/styles/theme";
+import { useSessionStore } from "@/stores/session-store";
 import { FileHtmlPreview } from "./html-preview";
+import { FilePanelLoading } from "./loading";
 import { FileMarkdownPreview } from "./markdown-preview";
-import type { builtinFilePanels } from "./catalog";
+import type { BuiltinFilePanelProps } from "./panels";
+import { SourcePanel } from "./source/panel";
+import type { RenderingFilePanel, SourceFilePanel } from "./catalog";
 
-interface FilePanelPreviewProps {
-  content: string;
-  filePath: string;
-  workspaceRoot: string;
-  client: DaemonClient | null;
-  serverId: string;
-  imagePreviewUri: string | null;
-}
-
-function MarkdownPanel(props: FilePanelPreviewProps) {
+/** Shows Loading until the rendered Markdown has laid out once; later re-reads keep the content. */
+function MarkdownPanel({ file, target }: BuiltinFilePanelProps) {
+  const text = useFileText(file);
+  const client = useSessionStore((state) => state.sessions[target.serverId]?.client ?? null);
+  const [rendered, setRendered] = useState(false);
+  const handleLayout = useCallback(() => setRendered(true), []);
+  if (text.status === "loading") return <FilePanelLoading />;
+  if (text.status === "error") return <FilePanelError message={text.error.message} />;
   return (
-    <View style={styles.previewScrollContainer}>
-      <ScrollView style={styles.previewContent} showsVerticalScrollIndicator>
-        <FileMarkdownPreview
-          source={props.content}
-          filePath={props.filePath}
-          workspaceRoot={props.workspaceRoot}
-          client={props.client}
-          serverId={props.serverId}
-        />
+    <View style={styles.container}>
+      <ScrollView style={styles.container} showsVerticalScrollIndicator>
+        <View onLayout={handleLayout}>
+          <FileMarkdownPreview
+            source={text.text}
+            filePath={target.path}
+            workspaceRoot={target.workspaceRoot}
+            client={client}
+            serverId={target.serverId}
+          />
+        </View>
       </ScrollView>
+      {rendered ? null : <FilePanelLoading />}
     </View>
   );
 }
 
-function HtmlPanel({ content }: FilePanelPreviewProps) {
+function HtmlPanel({ file }: BuiltinFilePanelProps) {
+  const text = useFileText(file);
+  if (text.status === "loading") return <FilePanelLoading />;
+  if (text.status === "error") return <FilePanelError message={text.error.message} />;
   return (
-    <View style={styles.previewScrollContainer}>
-      <FileHtmlPreview html={content} testID="file-html-preview" />
+    <View style={styles.container}>
+      <FileHtmlPreview html={text.text} testID="file-html-preview" />
     </View>
   );
 }
 
-const ThemedLoadingSpinner = withUnistyles(LoadingSpinner);
-const foregroundMutedColorMapping = (theme: Theme) => ({ color: theme.colors.foregroundMuted });
+function ImagePanel({ file }: BuiltinFilePanelProps) {
+  const url = useFileUrl(file);
+  if (url.status === "loading") return <FilePanelLoading />;
+  if (url.status === "error") return <FilePanelError message={url.error.message} />;
+  return <ZoomableImage uri={url.url} testID="image-file-preview" />;
+}
 
-function ImagePanel({ imagePreviewUri }: FilePanelPreviewProps) {
-  const { t } = useTranslation();
-  if (!imagePreviewUri) {
-    return (
-      <View style={styles.centerState}>
-        <ThemedLoadingSpinner size="small" uniProps={foregroundMutedColorMapping} />
-        <Text style={styles.loadingText}>{t("panels.file.loading")}</Text>
-      </View>
-    );
-  }
-  return <ZoomableImage uri={imagePreviewUri} testID="image-file-preview" />;
+function FilePanelError({ message }: { message: string }) {
+  return (
+    <View style={styles.centerState}>
+      <Text style={styles.errorText}>{message}</Text>
+    </View>
+  );
 }
 
 const components = {
   "builtin:markdown": MarkdownPanel,
   "builtin:html": HtmlPanel,
   "builtin:image": ImagePanel,
+  "builtin:source": SourcePanel,
 };
 
-export function FilePanelPreview({
+export function BuiltinFilePanelView({
   panel,
   ...props
-}: FilePanelPreviewProps & {
-  panel: (typeof builtinFilePanels)[number];
-}) {
+}: BuiltinFilePanelProps & { panel: RenderingFilePanel | SourceFilePanel }) {
   const Component = components[panel.id];
   return <Component {...props} />;
 }
 
 const styles = StyleSheet.create((theme) => ({
-  previewScrollContainer: { flex: 1, minHeight: 0 },
-  previewContent: { flex: 1, minHeight: 0 },
+  container: { flex: 1, minHeight: 0 },
   centerState: {
     flex: 1,
     alignItems: "center",
     justifyContent: "center",
-    gap: theme.spacing[3],
     padding: theme.spacing[4],
   },
-  loadingText: {
-    marginTop: theme.spacing[2],
-    color: theme.colors.foregroundMuted,
+  errorText: {
+    color: theme.colors.destructive,
     fontSize: theme.fontSize.base,
+    textAlign: "center",
   },
 }));

packages/app/src/file-panels/catalog.test.ts

@@ -1,86 +1,74 @@
 import { describe, expect, it } from "vitest";
-import { builtinFilePanels, isRenderedMarkdownFile } from "./catalog";
-import { resolveFilePanel } from "./resolve";
+import { filePanelCatalog } from "./catalog";
+import { resolveFilePanel, type FilePanelCandidate, type FilePanelFile } from "./resolve";
 
-function filePreviewRenderKind(path: string) {
-  const { panel } = resolveFilePanel({
-    file: { path, kind: "text", size: 100, hasBytes: false },
-    candidates: builtinFilePanels,
-    associations: {},
-  });
-  return panel ? panel.id.slice("builtin:".length) : null;
+const builtins = filePanelCatalog([]);
+
+const richMarkdown: FilePanelCandidate = {
+  id: "plugin:notes/rich",
+  builtin: false,
+  files: { extensions: ["md"] },
+};
+
+function textFile(path: string): FilePanelFile {
+  return { path, kind: "text" };
 }
 
-describe("isRenderedMarkdownFile", () => {
-  it("detects .md files", () => {
-    expect(isRenderedMarkdownFile("README.md")).toBe(true);
-    expect(isRenderedMarkdownFile("docs/guide.MD")).toBe(true);
-  });
+function candidateIds(file: FilePanelFile, candidates: readonly FilePanelCandidate[] = builtins) {
+  return resolveFilePanel({ file, candidates, associations: {} }).candidates.map(
+    (candidate) => candidate.id,
+  );
+}
 
-  it("detects .markdown files", () => {
-    expect(isRenderedMarkdownFile("notes.markdown")).toBe(true);
-    expect(isRenderedMarkdownFile("docs/CHANGELOG.MARKDOWN")).toBe(true);
-  });
-
-  it("does not treat .mdx files as rendered markdown", () => {
-    expect(isRenderedMarkdownFile("page.mdx")).toBe(false);
-  });
-
-  it("does not treat other text files as rendered markdown", () => {
-    expect(isRenderedMarkdownFile("src/index.ts")).toBe(false);
-    expect(isRenderedMarkdownFile("README.md.txt")).toBe(false);
-    expect(isRenderedMarkdownFile("plan.html")).toBe(false);
-  });
-});
-
-describe("filePreviewRenderKind", () => {
-  it("maps each renderable extension to its kind", () => {
-    expect(filePreviewRenderKind("README.md")).toBe("markdown");
-    expect(filePreviewRenderKind("notes.markdown")).toBe("markdown");
-    expect(filePreviewRenderKind("plan.html")).toBe("html");
-    expect(filePreviewRenderKind("docs/PLAN.HTML")).toBe("html");
-    expect(filePreviewRenderKind("plan.htm")).toBe("html");
-  });
-
-  it("returns null for files without a rendered preview", () => {
-    expect(filePreviewRenderKind("src/index.ts")).toBe(null);
-    expect(filePreviewRenderKind("page.mdx")).toBe(null);
-    expect(filePreviewRenderKind("index.html.erb")).toBe(null);
-  });
-});
+function panelId(file: FilePanelFile, candidates: readonly FilePanelCandidate[] = builtins) {
+  return resolveFilePanel({ file, candidates, associations: {} }).panel?.id ?? null;
+}
 
 describe("built-in file panels", () => {
+  it("opens each rendered extension with its panel and Source after it", () => {
+    expect(candidateIds(textFile("README.md"))).toEqual(["builtin:markdown", "builtin:source"]);
+    expect(panelId(textFile("notes.markdown"))).toBe("builtin:markdown");
+    expect(panelId(textFile("plan.html"))).toBe("builtin:html");
+    expect(panelId(textFile("docs/PLAN.HTML"))).toBe("builtin:html");
+    expect(panelId(textFile("plan.htm"))).toBe("builtin:html");
+  });
+
+  it("opens every other text file with Source, whatever its name", () => {
+    for (const path of ["src/index.ts", "page.mdx", "index.html.erb", "Dockerfile", "LICENSE"]) {
+      expect(candidateIds(textFile(path))).toEqual(["builtin:source"]);
+    }
+  });
+
+  it("puts plugin panels after the rendering built-ins and before Source", () => {
+    expect(candidateIds(textFile("README.md"), filePanelCatalog([richMarkdown]))).toEqual([
+      "builtin:markdown",
+      richMarkdown.id,
+      "builtin:source",
+    ]);
+    const onlyPlugin = filePanelCatalog([{ ...richMarkdown, files: { extensions: ["txt"] } }]);
+    expect(panelId(textFile("notes.txt"), onlyPlugin)).toBe(richMarkdown.id);
+  });
+
+  it("has no Source for files that are not text", () => {
+    expect(candidateIds({ path: "archive.zip", kind: "binary" })).toEqual([]);
+  });
+
   it.each(["png", "jpg", "jpeg", "gif", "webp", "svg"])(
     "registers the image extension %s",
     (extension) => {
       const resolution = resolveFilePanel({
-        file: {
-          path: `/capture.${extension.toUpperCase()}`,
-          kind: "image",
-          size: 512,
-          hasBytes: true,
-        },
-        candidates: builtinFilePanels,
+        file: { path: `/capture.${extension.toUpperCase()}`, kind: "image" },
+        candidates: builtins,
         associations: { [`ext:${extension}`]: "builtin:markdown" },
       });
       expect(resolution.panel?.id).toBe("builtin:image");
       expect(
         resolveFilePanel({
-          file: { path: "capture.png", kind: "binary", size: 512, hasBytes: false },
-          candidates: builtinFilePanels,
+          file: { path: "capture.png", kind: "binary" },
+          candidates: builtins,
           associations: {},
         }).panel,
       ).toBeNull();
     },
   );
-
-  it("does not impose a new preview size limit on built-in text panels", () => {
-    expect(
-      resolveFilePanel({
-        file: { path: "notes.md", kind: "text", size: 11 * 1024 * 1024, hasBytes: false },
-        candidates: builtinFilePanels,
-        associations: {},
-      }).panel?.id,
-    ).toBe("builtin:markdown");
-  });
 });

packages/app/src/file-panels/catalog.ts

@@ -1,28 +1,43 @@
-import { filePanelExtension, type FilePanelCandidate } from "./resolve";
+import type { FilePanelCandidate } from "./resolve";
 
-const markdownPanel = {
-  id: "builtin:markdown",
-  files: { extensions: ["md", "markdown"] },
-  document: "text",
-  maxBytes: Infinity,
-} as const satisfies FilePanelCandidate;
-
-export const builtinFilePanels = [
-  markdownPanel,
+const renderingPanels = [
+  {
+    id: "builtin:markdown",
+    builtin: true,
+    files: { extensions: ["md", "markdown"] },
+    fileKind: "text",
+  },
   {
     id: "builtin:html",
+    builtin: true,
     files: { extensions: ["html", "htm"] },
-    document: "text",
-    maxBytes: Infinity,
+    fileKind: "text",
   },
   {
     id: "builtin:image",
+    builtin: true,
     files: { extensions: ["png", "jpg", "jpeg", "gif", "webp", "svg"] },
-    document: "bytes",
-    maxBytes: Infinity,
+    fileKind: "image",
   },
 ] as const satisfies readonly FilePanelCandidate[];
 
-export function isRenderedMarkdownFile(path: string): boolean {
-  return markdownPanel.files.extensions.some((extension) => extension === filePanelExtension(path));
+/** Paseo's editor. Every text file has it, so a text file always opens with some panel. */
+export const sourceFilePanel = {
+  id: "builtin:source",
+  builtin: true,
+  files: "all",
+  fileKind: "text",
+} as const satisfies FilePanelCandidate;
+
+export type RenderingFilePanel = (typeof renderingPanels)[number];
+export type SourceFilePanel = typeof sourceFilePanel;
+
+/**
+ * Every panel a host offers, in resolver order: the built-ins that render a file, then plugin
+ * panels, then Source. Source is last so it is the default only when nothing else claims the file.
+ */
+export function filePanelCatalog<Plugin extends FilePanelCandidate>(
+  pluginPanels: readonly Plugin[],
+): readonly (RenderingFilePanel | Plugin | SourceFilePanel)[] {
+  return [...renderingPanels, ...pluginPanels, sourceFilePanel];
 }

packages/app/src/file-panels/choice/hook.ts

@@ -0,0 +1,88 @@
+import { useCallback, useEffect, useMemo, useState, useSyncExternalStore } from "react";
+import { usePaneContext } from "@/panels/pane-context";
+import type { PanelInstanceIdentity } from "@/panels/panel-instance-attributes";
+import { useFilePanelAssociations } from "../associations";
+import { sourceFilePanel } from "../catalog";
+import { useFilePanels, type FilePanel } from "../panels";
+import { resolveFilePanel, type FilePanelFileKind } from "../resolve";
+import { chosenPanelFor, FilePanelChoiceModel, type FilePanelChoiceSnapshot } from "./model";
+import { getFilePanelChoice, registerFilePanelChoice, subscribeFilePanelChoices } from "./registry";
+
+export type FilePanelChoice = FilePanelChoiceModel<FilePanel>;
+
+/**
+ * The file tab's panel: resolves it from the catalog, the device associations and this tab's
+ * choice, and owns the picker and "Open with…" for it.
+ */
+export function useFilePanelChoice(input: {
+  serverId: string;
+  targetKey: string | null;
+  path: string;
+  /** The kind the file's stat reports, or null before the stat. */
+  fileKind: FilePanelFileKind | null;
+  /** The tab is on screen. */
+  presentable: boolean;
+  /** Identifies the tab's latest request to show a line, or null when it targets no line. */
+  lineNavigation: number | null;
+}): { panel: FilePanel | null; choice: FilePanelChoice } {
+  const { targetKey, path, fileKind, presentable, lineNavigation } = input;
+  const { serverId, workspaceId, tabId } = usePaneContext();
+  const candidates = useFilePanels(input.serverId);
+  const { associations, remember } = useFilePanelAssociations();
+  const [choice] = useState(
+    () => new FilePanelChoiceModel<FilePanel>({ remember, linePanelId: sourceFilePanel.id }),
+  );
+  // From the subscribed snapshot: React Compiler caches reads off the stable model object.
+  const chosenPanelId = chosenPanelFor(useFilePanelChoiceSnapshot(choice), targetKey);
+  const resolution = useMemo(
+    () =>
+      fileKind
+        ? resolveFilePanel({
+            file: { path, kind: fileKind },
+            candidates,
+            associations,
+            choice: chosenPanelId,
+          })
+        : null,
+    [associations, candidates, chosenPanelId, fileKind, path],
+  );
+
+  useEffect(() => {
+    choice.observe({ targetKey, resolution, presentable, lineNavigation });
+  }, [choice, lineNavigation, presentable, resolution, targetKey]);
+  useEffect(
+    () => registerFilePanelChoice({ serverId, workspaceId, tabId }, choice),
+    [choice, serverId, tabId, workspaceId],
+  );
+
+  return { panel: resolution?.panel ?? null, choice };
+}
+
+const NO_CHOICE_SNAPSHOT: FilePanelChoiceSnapshot<FilePanel> = {
+  targetKey: null,
+  chosenPanelId: null,
+  picker: null,
+  openWith: null,
+};
+const subscribeNothing = () => () => {};
+const getNoChoiceSnapshot = () => NO_CHOICE_SNAPSHOT;
+
+/** The choice of an open file tab, looked up by the tab's identity, for chrome outside its pane. */
+export function useTabFilePanelChoice(identity: PanelInstanceIdentity): FilePanelChoice | null {
+  const { serverId, workspaceId, tabId } = identity;
+  const getSnapshot = useCallback(
+    () => getFilePanelChoice({ serverId, workspaceId, tabId }),
+    [serverId, tabId, workspaceId],
+  );
+  return useSyncExternalStore(subscribeFilePanelChoices, getSnapshot, getSnapshot);
+}
+
+export function useFilePanelChoiceSnapshot(
+  choice: FilePanelChoice | null,
+): FilePanelChoiceSnapshot<FilePanel> {
+  return useSyncExternalStore(
+    choice?.subscribe ?? subscribeNothing,
+    choice?.getSnapshot ?? getNoChoiceSnapshot,
+    choice?.getSnapshot ?? getNoChoiceSnapshot,
+  );
+}

packages/app/src/file-panels/choice/model.test.ts

@@ -0,0 +1,203 @@
+import { describe, expect, it } from "vitest";
+import { filePanelCatalog, sourceFilePanel } from "../catalog";
+import { resolveFilePanel, type FilePanelCandidate } from "../resolve";
+import { chosenPanelFor, FilePanelChoiceModel } from "./model";
+
+const rich: FilePanelCandidate = {
+  id: "plugin:notes/rich",
+  builtin: false,
+  files: { extensions: ["md", "markdown"] },
+};
+const markdown = "builtin:markdown";
+const source = sourceFilePanel.id;
+
+/** A file tab: resolves against the shared associations and feeds the result to its model. */
+function openTab(
+  associations: Record<string, string>,
+  candidates: FilePanelCandidate[] = [...filePanelCatalog([rich])],
+  options: { presentable?: boolean; path?: string; lineNavigation?: number | null } = {},
+) {
+  const model = new FilePanelChoiceModel<FilePanelCandidate>({
+    remember(selectorKey, panelId) {
+      if (panelId === null) delete associations[selectorKey];
+      else associations[selectorKey] = panelId;
+    },
+    linePanelId: source,
+  });
+  let targetKey = `/repo:${options.path ?? "notes.md"}`;
+  let presentable = options.presentable ?? true;
+  let lineNavigation = options.lineNavigation ?? null;
+  const resolve = () =>
+    resolveFilePanel({
+      file: { path: targetKey.split(":")[1]!, kind: "text" },
+      candidates,
+      associations,
+      choice: chosenPanelFor(model.getSnapshot(), targetKey),
+    });
+  // Like the hook: observe, then render what the model's choice resolves to.
+  const render = () => {
+    model.observe({ targetKey, resolution: resolve(), presentable, lineNavigation });
+    return resolve().panel?.id ?? null;
+  };
+  render();
+  return {
+    model,
+    render,
+    panel: () => render(),
+    picker: () => model.getSnapshot().picker,
+    retarget(path: string) {
+      targetKey = `/repo:${path}`;
+      return render();
+    },
+    setPresentable(next: boolean) {
+      presentable = next;
+      return render();
+    },
+    navigateToLine(revision: number) {
+      lineNavigation = revision;
+      return render();
+    },
+  };
+}
+
+describe("FilePanelChoiceModel", () => {
+  it("asks once per tab open over the first candidate, and dismissing keeps it", () => {
+    const associations = {};
+    const tab = openTab(associations);
+    expect(tab.panel()).toBe(markdown);
+    expect(tab.picker()).toMatchObject({
+      selectorKey: "ext:md",
+      selectedPanelId: markdown,
+      remember: false,
+    });
+    expect(tab.picker()?.candidates.map((candidate) => candidate.id)).toEqual([
+      markdown,
+      rich.id,
+      source,
+    ]);
+    tab.model.dismissPicker();
+    expect(tab.picker()).toBeNull();
+    expect(tab.panel()).toBe(markdown);
+    expect(tab.picker()).toBeNull();
+    expect(associations).toEqual({});
+
+    expect(openTab(associations).picker()).not.toBeNull();
+  });
+
+  it("never asks between built-in panels, and switches between them", () => {
+    const tab = openTab({}, [...filePanelCatalog([])]);
+    expect(tab.panel()).toBe(markdown);
+    expect(tab.picker()).toBeNull();
+    expect(tab.model.getSnapshot().openWith?.candidates.map((candidate) => candidate.id)).toEqual([
+      markdown,
+      source,
+    ]);
+    tab.model.openWith(source);
+    expect(tab.panel()).toBe(source);
+    expect(tab.picker()).toBeNull();
+  });
+
+  it("opens a file only Source claims with Source and nothing to choose", () => {
+    const tab = openTab({}, [...filePanelCatalog([rich])], { path: "index.ts" });
+    expect(tab.panel()).toBe(source);
+    expect(tab.picker()).toBeNull();
+    expect(tab.model.getSnapshot().openWith).toBeNull();
+  });
+
+  it("remembers the choice when Don't ask me again is checked", () => {
+    const associations: Record<string, string> = {};
+    const tab = openTab(associations);
+    tab.model.selectInPicker(rich.id);
+    tab.model.setRemember(true);
+    tab.model.confirmPicker();
+    expect(tab.panel()).toBe(rich.id);
+    expect(associations).toEqual({ "ext:md": rich.id });
+
+    const next = openTab(associations);
+    expect(next.panel()).toBe(rich.id);
+    expect(next.picker()).toBeNull();
+  });
+
+  it("uses an unremembered choice for this tab only and asks again on the next open", () => {
+    const associations = {};
+    const tab = openTab(associations);
+    tab.model.selectInPicker(rich.id);
+    tab.model.confirmPicker();
+    expect(tab.panel()).toBe(rich.id);
+    expect(associations).toEqual({});
+
+    const next = openTab(associations);
+    expect(next.panel()).toBe(markdown);
+    expect(next.picker()).not.toBeNull();
+  });
+
+  it("does not ask with an association or while the tab is in the background", () => {
+    expect(openTab({ "ext:md": rich.id }).picker()).toBeNull();
+    expect(openTab({ "ext:md": source }).panel()).toBe(source);
+
+    const background = openTab({}, undefined, { presentable: false });
+    expect(background.picker()).toBeNull();
+    background.setPresentable(true);
+    expect(background.picker()).not.toBeNull();
+  });
+
+  it("opens Source for a line target without asking, and again on each new one", () => {
+    const tab = openTab({}, undefined, { lineNavigation: 1 });
+    expect(tab.panel()).toBe(source);
+    expect(tab.picker()).toBeNull();
+
+    tab.model.openWith(rich.id);
+    expect(tab.panel()).toBe(rich.id);
+    expect(tab.navigateToLine(1)).toBe(rich.id);
+    expect(tab.navigateToLine(2)).toBe(source);
+  });
+
+  it("opens Source for the same line target in a retargeted tab", () => {
+    const tab = openTab({}, undefined, { lineNavigation: 1 });
+    tab.model.openWith(markdown);
+    expect(tab.retarget("other.md")).toBe(source);
+  });
+
+  it("starts a new open when the tab is retargeted", () => {
+    const tab = openTab({});
+    tab.model.selectInPicker(rich.id);
+    tab.model.confirmPicker();
+    expect(tab.retarget("other.md")).toBe(markdown);
+    expect(tab.picker()).not.toBeNull();
+  });
+
+  it("switches with Open with and toggles Always use without moving the tab", () => {
+    const associations: Record<string, string> = {};
+    const tab = openTab(associations);
+    tab.model.dismissPicker();
+    expect(tab.model.getSnapshot().openWith).toMatchObject({
+      activePanelId: markdown,
+      remembered: false,
+    });
+
+    tab.model.openWith(rich.id);
+    expect(tab.panel()).toBe(rich.id);
+    tab.model.toggleAlwaysUse();
+    expect(associations).toEqual({ "ext:md": rich.id });
+    tab.render();
+    expect(tab.model.getSnapshot().openWith?.remembered).toBe(true);
+
+    tab.model.openWith(markdown);
+    expect(tab.panel()).toBe(markdown);
+    expect(tab.model.getSnapshot().openWith?.remembered).toBe(false);
+    tab.model.openWith(rich.id);
+    tab.render();
+    tab.model.toggleAlwaysUse();
+    expect(associations).toEqual({});
+    expect(tab.panel()).toBe(rich.id);
+  });
+
+  it("asks when a plugin panel arrives after the file first rendered", () => {
+    const candidates: FilePanelCandidate[] = [...filePanelCatalog([])];
+    const tab = openTab({}, candidates);
+    expect(tab.picker()).toBeNull();
+    candidates.splice(1, 0, rich);
+    tab.render();
+    expect(tab.picker()).not.toBeNull();
+  });
+});

packages/app/src/file-panels/choice/model.ts

@@ -0,0 +1,195 @@
+import { asksForFilePanel, type FilePanelCandidate, type FilePanelResolution } from "../resolve";
+
+/** What the file tab currently resolves; `resolution` is null until the file has been read. */
+export interface FilePanelChoiceSource<Candidate extends FilePanelCandidate> {
+  targetKey: string | null;
+  resolution: FilePanelResolution<Candidate> | null;
+  /** The tab is on screen, so a picker shown now is seen over the panel it chooses for. */
+  presentable: boolean;
+  /** Identifies the tab's latest request to show a line, or null when it targets no line. */
+  lineNavigation: number | null;
+}
+
+export interface FilePanelPickerState<Candidate> {
+  selectorKey: string;
+  candidates: readonly Candidate[];
+  selectedPanelId: string;
+  remember: boolean;
+}
+
+export interface FilePanelOpenWithState<Candidate> {
+  selectorKey: string;
+  candidates: readonly Candidate[];
+  activePanelId: string;
+  /** The active panel is the one remembered for `selectorKey`. */
+  remembered: boolean;
+}
+
+export interface FilePanelChoiceSnapshot<Candidate> {
+  targetKey: string | null;
+  /** The panel picked for this tab open. Resolution prefers it over the association. */
+  chosenPanelId: string | null;
+  picker: FilePanelPickerState<Candidate> | null;
+  /** Present only when the file has more than one candidate; drives the bar's panel switcher. */
+  openWith: FilePanelOpenWithState<Candidate> | null;
+}
+
+export interface FilePanelChoiceDeps {
+  /** Writes (or clears, with null) the device-wide association for a selector key. */
+  remember(selectorKey: string, panelId: string | null): void;
+  /** The panel a line target opens: Source, the panel that shows lines. */
+  linePanelId: string;
+}
+
+/** The tab choice that applies to `targetKey`; a choice never outlives its open. */
+export function chosenPanelFor(
+  snapshot: FilePanelChoiceSnapshot<unknown>,
+  targetKey: string | null,
+): string | null {
+  return snapshot.targetKey === targetKey ? snapshot.chosenPanelId : null;
+}
+
+const EMPTY: FilePanelChoiceSnapshot<never> = {
+  targetKey: null,
+  chosenPanelId: null,
+  picker: null,
+  openWith: null,
+};
+
+/**
+ * Which file panel one file tab shows, and whether to ask.
+ *
+ * A tab open is one target in one tab: the picker is offered at most once per open, the first
+ * time the tab is on screen with a plugin panel among several candidates and nothing remembered.
+ * Built-in panels alone never ask. A line target opens the line panel the way "Open with…" does.
+ * Retargeting the tab starts a new open. Choices made here apply to this tab; only "Don't ask me
+ * again" and "Always use" write the association every later open reads.
+ */
+export class FilePanelChoiceModel<Candidate extends FilePanelCandidate> {
+  private readonly listeners = new Set<() => void>();
+  private snapshot: FilePanelChoiceSnapshot<Candidate> = EMPTY;
+  private asked = false;
+  private openedLineNavigation: number | null = null;
+
+  constructor(private readonly deps: FilePanelChoiceDeps) {}
+
+  subscribe = (listener: () => void): (() => void) => {
+    this.listeners.add(listener);
+    return () => this.listeners.delete(listener);
+  };
+
+  getSnapshot = (): FilePanelChoiceSnapshot<Candidate> => this.snapshot;
+
+  observe(source: FilePanelChoiceSource<Candidate>): void {
+    let current = this.snapshot;
+    if (source.targetKey !== current.targetKey) {
+      this.asked = false;
+      this.openedLineNavigation = null;
+      current = { ...EMPTY, targetKey: source.targetKey };
+    }
+    if (source.lineNavigation !== null && source.lineNavigation !== this.openedLineNavigation) {
+      this.openedLineNavigation = source.lineNavigation;
+      current = { ...current, chosenPanelId: this.deps.linePanelId, picker: null };
+    }
+    const openWith = stableOpenWith(current.openWith, openWithState(source.resolution));
+    let picker = openWith ? current.picker : null;
+    // Decided once per open, the first time there is something to ask about on screen. An
+    // association forgotten while the tab stays open is asked about on the next open.
+    if (!this.asked && source.presentable && openWith && asksForFilePanel(openWith.candidates)) {
+      this.asked = true;
+      const remembered = Boolean(source.resolution?.associatedPanelId);
+      if (!remembered && current.chosenPanelId === null) {
+        picker = {
+          selectorKey: openWith.selectorKey,
+          candidates: openWith.candidates,
+          selectedPanelId: openWith.activePanelId,
+          remember: false,
+        };
+      }
+    }
+    this.publish({ ...current, openWith, picker });
+  }
+
+  selectInPicker(panelId: string): void {
+    const picker = this.snapshot.picker;
+    if (!picker) return;
+    this.publish({ ...this.snapshot, picker: { ...picker, selectedPanelId: panelId } });
+  }
+
+  setRemember(remember: boolean): void {
+    const picker = this.snapshot.picker;
+    if (!picker) return;
+    this.publish({ ...this.snapshot, picker: { ...picker, remember } });
+  }
+
+  confirmPicker(): void {
+    const picker = this.snapshot.picker;
+    if (!picker) return;
+    if (picker.remember) this.deps.remember(picker.selectorKey, picker.selectedPanelId);
+    this.publish({ ...this.snapshot, chosenPanelId: picker.selectedPanelId, picker: null });
+  }
+
+  /** Keeps whatever the tab shows now; the next open asks again. */
+  dismissPicker(): void {
+    if (!this.snapshot.picker) return;
+    this.publish({ ...this.snapshot, picker: null });
+  }
+
+  openWith(panelId: string): void {
+    this.publish({ ...this.snapshot, chosenPanelId: panelId, picker: null });
+  }
+
+  /** Remembers the active panel, or forgets it when it already is the remembered one. */
+  toggleAlwaysUse(): void {
+    const openWith = this.snapshot.openWith;
+    if (!openWith) return;
+    if (!openWith.remembered) {
+      this.deps.remember(openWith.selectorKey, openWith.activePanelId);
+      return;
+    }
+    // Forgetting must not move the tab off the panel it is showing.
+    this.publish({ ...this.snapshot, chosenPanelId: openWith.activePanelId });
+    this.deps.remember(openWith.selectorKey, null);
+  }
+
+  private publish(next: FilePanelChoiceSnapshot<Candidate>): void {
+    const current = this.snapshot;
+    if (
+      current.targetKey === next.targetKey &&
+      current.chosenPanelId === next.chosenPanelId &&
+      current.picker === next.picker &&
+      current.openWith === next.openWith
+    ) {
+      return;
+    }
+    this.snapshot = next;
+    for (const listener of this.listeners) listener();
+  }
+}
+
+function openWithState<Candidate extends FilePanelCandidate>(
+  resolution: FilePanelResolution<Candidate> | null,
+): FilePanelOpenWithState<Candidate> | null {
+  if (!resolution?.panel || resolution.candidates.length < 2) return null;
+  return {
+    selectorKey: resolution.selectorKey,
+    candidates: resolution.candidates,
+    activePanelId: resolution.panel.id,
+    remembered: resolution.associatedPanelId === resolution.panel.id,
+  };
+}
+
+/** Keeps the published object when nothing in it changed, so subscribers do not re-render. */
+function stableOpenWith<Candidate>(
+  current: FilePanelOpenWithState<Candidate> | null,
+  next: FilePanelOpenWithState<Candidate> | null,
+): FilePanelOpenWithState<Candidate> | null {
+  if (!current || !next) return next;
+  const same =
+    current.selectorKey === next.selectorKey &&
+    current.activePanelId === next.activePanelId &&
+    current.remembered === next.remembered &&
+    current.candidates.length === next.candidates.length &&
+    current.candidates.every((candidate, index) => candidate === next.candidates[index]);
+  return same ? current : next;
+}

packages/app/src/file-panels/choice/open-with.tsx

@@ -0,0 +1,175 @@
+import { useCallback, useMemo, type ReactElement } from "react";
+import { useTranslation } from "react-i18next";
+import { withUnistyles } from "react-native-unistyles";
+import { Ellipsis } from "lucide-react-native";
+import {
+  MenuItem,
+  MenuSeparator,
+  MenuSubTrigger,
+  type MenuPageDefinition,
+} from "@/components/ui/menu";
+import { DropdownMenu, DropdownMenuContent } from "@/components/ui/dropdown-menu";
+import { extraMutedIconColorMapping } from "@/components/ui/icon-button-chrome";
+import { ToolbarButton, paneContentToolbarIconSize } from "@/components/ui/pane-content-toolbar";
+import { useIsCompactFormFactor } from "@/constants/layout";
+import type { PanelInstanceIdentity } from "@/panels/panel-instance-attributes";
+import { PluginIconView } from "@/plugins/icons";
+import type { Theme } from "@/styles/theme";
+import type { FilePanel } from "../panels";
+import { useFilePanelChoiceSnapshot, useTabFilePanelChoice, type FilePanelChoice } from "./hook";
+import { filePanelAlwaysUseLabel, filePanelIcon, filePanelOptionLabel } from "./presentation";
+
+const OPEN_WITH_PAGE_ID = "filePanelOpenWith";
+const MENU_ICON_SIZE = 16;
+
+const ThemedEllipsis = withUnistyles(Ellipsis);
+const ThemedPanelIcon = withUnistyles(PluginIconView);
+const mutedIconMapping = (theme: Theme) => ({ color: theme.colors.foregroundMuted });
+
+const NO_PAGES: readonly MenuPageDefinition[] = [];
+
+export interface FilePanelOpenWithMenu {
+  /** The "Open with…" row, or null when the file has one panel or none. */
+  trigger: ReactElement | null;
+  /** The page the row opens; pass to the menu surface. */
+  pages: readonly MenuPageDefinition[];
+}
+
+/** "Open with…" for a file tab's context menu, found by the tab's identity. */
+export function useFilePanelOpenWithMenu(
+  identity: PanelInstanceIdentity,
+  testIDBase: string,
+): FilePanelOpenWithMenu {
+  return useOpenWithMenu(useTabFilePanelChoice(identity), testIDBase);
+}
+
+/**
+ * The file bar's overflow: remembering the panel the bar's switcher shows. Renders nothing unless
+ * the file has more than one panel.
+ */
+export function FilePanelBarMenu({ choice }: { choice: FilePanelChoice }) {
+  const { t } = useTranslation();
+  const compact = useIsCompactFormFactor();
+  const { openWith } = useFilePanelChoiceSnapshot(choice);
+  if (!openWith) return null;
+  const label = t("panels.file.filePanels.actions");
+  return (
+    <DropdownMenu compactMode="sheet">
+      <ToolbarButton kind="menu" label={label} compact={compact} testID="file-panel-bar-menu">
+        <ThemedEllipsis
+          size={paneContentToolbarIconSize(compact)}
+          uniProps={extraMutedIconColorMapping}
+        />
+      </ToolbarButton>
+      <DropdownMenuContent
+        align="end"
+        width={240}
+        sheetTitle={label}
+        testID="file-panel-bar-menu-surface"
+      >
+        <AlwaysUseItem
+          choice={choice}
+          label={filePanelAlwaysUseLabel(t, openWith.selectorKey)}
+          selected={openWith.remembered}
+          testID="file-panel-bar-menu-always-use"
+        />
+      </DropdownMenuContent>
+    </DropdownMenu>
+  );
+}
+
+function useOpenWithMenu(
+  choice: FilePanelChoice | null,
+  testIDBase: string,
+): FilePanelOpenWithMenu {
+  const { t } = useTranslation();
+  const { openWith } = useFilePanelChoiceSnapshot(choice);
+  return useMemo(() => {
+    if (!choice || !openWith) return { trigger: null, pages: NO_PAGES };
+    const title = t("panels.file.filePanels.openWith");
+    return {
+      trigger: (
+        <MenuSubTrigger id={OPEN_WITH_PAGE_ID} testID={`${testIDBase}-open-with`}>
+          {title}
+        </MenuSubTrigger>
+      ),
+      pages: [
+        {
+          id: OPEN_WITH_PAGE_ID,
+          title,
+          content: (
+            <>
+              {openWith.candidates.map((panel) => (
+                <OpenWithItem
+                  key={panel.id}
+                  choice={choice}
+                  panel={panel}
+                  label={filePanelOptionLabel(t, panel)}
+                  selected={panel.id === openWith.activePanelId}
+                  testID={`${testIDBase}-open-with-${panel.id}`}
+                />
+              ))}
+              <MenuSeparator />
+              <AlwaysUseItem
+                choice={choice}
+                label={filePanelAlwaysUseLabel(t, openWith.selectorKey)}
+                selected={openWith.remembered}
+                testID={`${testIDBase}-always-use`}
+              />
+            </>
+          ),
+        },
+      ],
+    };
+  }, [choice, openWith, t, testIDBase]);
+}
+
+function OpenWithItem({
+  choice,
+  panel,
+  label,
+  selected,
+  testID,
+}: {
+  choice: FilePanelChoice;
+  panel: FilePanel;
+  label: string;
+  selected: boolean;
+  testID: string;
+}) {
+  const handleSelect = useCallback(() => choice.openWith(panel.id), [choice, panel.id]);
+  const leading = useMemo(
+    () => (
+      <ThemedPanelIcon
+        icon={filePanelIcon(panel)}
+        size={MENU_ICON_SIZE}
+        uniProps={mutedIconMapping}
+      />
+    ),
+    [panel],
+  );
+  return (
+    <MenuItem selected={selected} leading={leading} onSelect={handleSelect} testID={testID}>
+      {label}
+    </MenuItem>
+  );
+}
+
+function AlwaysUseItem({
+  choice,
+  label,
+  selected,
+  testID,
+}: {
+  choice: FilePanelChoice;
+  label: string;
+  selected: boolean;
+  testID: string;
+}) {
+  const handleSelect = useCallback(() => choice.toggleAlwaysUse(), [choice]);
+  return (
+    <MenuItem selected={selected} onSelect={handleSelect} testID={testID}>
+      {label}
+    </MenuItem>
+  );
+}

packages/app/src/file-panels/choice/picker.tsx

@@ -0,0 +1,233 @@
+import { useCallback, useMemo, useState } from "react";
+import { useTranslation } from "react-i18next";
+import { Text, View } from "react-native";
+import { StyleSheet, withUnistyles } from "react-native-unistyles";
+import { Check } from "lucide-react-native";
+import { AdaptiveModalSheet, type SheetHeader } from "@/components/adaptive-modal-sheet";
+import { Button } from "@/components/ui/button";
+import { PressHighlight } from "@/components/ui/press-highlight";
+import { PluginIconView } from "@/plugins/icons";
+import { settingsStyles } from "@/styles/settings";
+import type { Theme } from "@/styles/theme";
+import type { FilePanel } from "../panels";
+import type { FilePanelPickerState } from "./model";
+import { useFilePanelChoiceSnapshot, type FilePanelChoice } from "./hook";
+import { filePanelIcon, filePanelOptionLabel, filePanelPickerTitle } from "./presentation";
+
+const ThemedCheck = withUnistyles(Check);
+const ThemedPanelIcon = withUnistyles(PluginIconView);
+const checkedIconMapping = (theme: Theme) => ({ color: theme.colors.accentForeground });
+const mutedIconMapping = (theme: Theme) => ({ color: theme.colors.foregroundMuted });
+
+/** The first-open question for a file with several panels, over the panel already showing. */
+export function FilePanelPicker({ choice }: { choice: FilePanelChoice }) {
+  const { t } = useTranslation();
+  const { picker } = useFilePanelChoiceSnapshot(choice);
+  // The sheet animates out after the model has closed the picker; keep drawing what it asked.
+  const [shown, setShown] = useState(picker);
+  if (picker && picker !== shown) setShown(picker);
+  const content = picker ?? shown;
+
+  const dismiss = useCallback(() => choice.dismissPicker(), [choice]);
+  const confirm = useCallback(() => choice.confirmPicker(), [choice]);
+  const toggleRemember = useCallback(
+    () => choice.setRemember(!choice.getSnapshot().picker?.remember),
+    [choice],
+  );
+  const header = useMemo<SheetHeader>(
+    () => ({ title: content ? filePanelPickerTitle(t, content.selectorKey) : "" }),
+    [content, t],
+  );
+  const footer = useMemo(
+    () => (
+      <Button
+        style={styles.footerButton}
+        variant="default"
+        onPress={confirm}
+        testID="file-panel-picker-use"
+      >
+        {t("panels.file.filePanels.use")}
+      </Button>
+    ),
+    [confirm, t],
+  );
+
+  return (
+    <AdaptiveModalSheet
+      header={header}
+      visible={picker !== null}
+      onClose={dismiss}
+      footer={footer}
+      snapPoints={PICKER_SNAP_POINTS}
+      desktopMaxWidth={420}
+      testID="file-panel-picker"
+    >
+      {content ? (
+        <PickerBody choice={choice} picker={content} onToggleRemember={toggleRemember} />
+      ) : null}
+    </AdaptiveModalSheet>
+  );
+}
+
+const PICKER_SNAP_POINTS = ["60%", "90%"];
+
+function PickerBody({
+  choice,
+  picker,
+  onToggleRemember,
+}: {
+  choice: FilePanelChoice;
+  picker: FilePanelPickerState<FilePanel>;
+  onToggleRemember: () => void;
+}) {
+  const { t } = useTranslation();
+  const select = useCallback((panelId: string) => choice.selectInPicker(panelId), [choice]);
+  return (
+    <>
+      <View style={settingsStyles.card} accessibilityRole="radiogroup">
+        {picker.candidates.map((panel, index) => (
+          <PanelRadioRow
+            key={panel.id}
+            panel={panel}
+            label={filePanelOptionLabel(t, panel)}
+            selected={panel.id === picker.selectedPanelId}
+            withBorder={index > 0}
+            onSelect={select}
+          />
+        ))}
+      </View>
+      <CheckboxRow
+        label={t("panels.file.filePanels.dontAskAgain")}
+        checked={picker.remember}
+        onToggle={onToggleRemember}
+      />
+    </>
+  );
+}
+
+function PanelRadioRow({
+  panel,
+  label,
+  selected,
+  withBorder,
+  onSelect,
+}: {
+  panel: FilePanel;
+  label: string;
+  selected: boolean;
+  withBorder: boolean;
+  onSelect: (panelId: string) => void;
+}) {
+  const handlePress = useCallback(() => onSelect(panel.id), [onSelect, panel.id]);
+  const accessibilityState = useMemo(() => ({ checked: selected }), [selected]);
+  const rowStyle = useMemo(
+    () => [settingsStyles.row, withBorder ? settingsStyles.rowBorder : null, styles.optionRow],
+    [withBorder],
+  );
+  return (
+    <PressHighlight
+      style={rowStyle}
+      onPress={handlePress}
+      accessibilityRole="radio"
+      accessibilityLabel={label}
+      accessibilityState={accessibilityState}
+      aria-checked={selected}
+    >
+      <View style={selected ? styles.radioSelected : styles.radio}>
+        {selected ? <View style={styles.radioDot} /> : null}
+      </View>
+      <ThemedPanelIcon icon={filePanelIcon(panel)} size={16} uniProps={mutedIconMapping} />
+      <Text style={settingsStyles.rowTitle} numberOfLines={1}>
+        {label}
+      </Text>
+    </PressHighlight>
+  );
+}
+
+function CheckboxRow({
+  label,
+  checked,
+  onToggle,
+}: {
+  label: string;
+  checked: boolean;
+  onToggle: () => void;
+}) {
+  const accessibilityState = useMemo(() => ({ checked }), [checked]);
+  return (
+    <PressHighlight
+      style={styles.checkboxRow}
+      onPress={onToggle}
+      accessibilityRole="checkbox"
+      accessibilityLabel={label}
+      accessibilityState={accessibilityState}
+      aria-checked={checked}
+      testID="file-panel-picker-remember"
+    >
+      <View style={checked ? styles.checkboxChecked : styles.checkbox}>
+        {checked ? <ThemedCheck size={14} uniProps={checkedIconMapping} /> : null}
+      </View>
+      <Text style={settingsStyles.rowTitle}>{label}</Text>
+    </PressHighlight>
+  );
+}
+
+const styles = StyleSheet.create((theme) => ({
+  footerButton: {
+    flex: 1,
+  },
+  optionRow: {
+    justifyContent: "flex-start",
+    gap: theme.spacing[3],
+  },
+  radio: {
+    width: 18,
+    height: 18,
+    borderRadius: theme.borderRadius.full,
+    borderWidth: 1,
+    borderColor: theme.colors.border,
+    alignItems: "center",
+    justifyContent: "center",
+  },
+  radioSelected: {
+    width: 18,
+    height: 18,
+    borderRadius: theme.borderRadius.full,
+    borderWidth: 1,
+    borderColor: theme.colors.accent,
+    alignItems: "center",
+    justifyContent: "center",
+  },
+  radioDot: {
+    width: 8,
+    height: 8,
+    borderRadius: theme.borderRadius.full,
+    backgroundColor: theme.colors.accent,
+  },
+  checkboxRow: {
+    flexDirection: "row",
+    alignItems: "center",
+    gap: theme.spacing[3],
+    paddingVertical: theme.spacing[2],
+    paddingHorizontal: theme.spacing[4],
+  },
+  checkbox: {
+    width: 18,
+    height: 18,
+    borderRadius: theme.borderRadius.sm,
+    borderWidth: 1,
+    borderColor: theme.colors.border,
+    alignItems: "center",
+    justifyContent: "center",
+  },
+  checkboxChecked: {
+    width: 18,
+    height: 18,
+    borderRadius: theme.borderRadius.sm,
+    borderWidth: 1,
+    borderColor: theme.colors.accent,
+    backgroundColor: theme.colors.accent,
+    alignItems: "center",
+    justifyContent: "center",
+  },
+}));

packages/app/src/file-panels/choice/presentation.ts

@@ -0,0 +1,52 @@
+import type { TFunction } from "i18next";
+import type { PluginIcon } from "@getpaseo/plugin/client";
+import type { FilePanel } from "../panels";
+import { parseFilePanelSelectorKey } from "../resolve";
+
+const BUILTIN_PRESENTATION = {
+  "builtin:markdown": { title: "markdown", icon: "FileText" },
+  "builtin:html": { title: "html", icon: "FileCode" },
+  "builtin:image": { title: "image", icon: "Image" },
+  "builtin:source": { title: "source", icon: "Code" },
+} as const;
+
+export function filePanelIcon(panel: FilePanel): PluginIcon {
+  return panel.builtin ? BUILTIN_PRESENTATION[panel.id].icon : panel.contribution.icon;
+}
+
+/** "Markdown", "Rich Markdown": the panel switcher's label. */
+export function filePanelTitle(t: TFunction, panel: FilePanel): string {
+  return panel.builtin
+    ? t(`panels.file.filePanels.builtin.${BUILTIN_PRESENTATION[panel.id].title}`)
+    : panel.plugin.i18n.resolve(panel.contribution.title, panel.plugin.locale);
+}
+
+/** "Markdown — Paseo", "Rich Markdown — markdown-panel". */
+export function filePanelOptionLabel(t: TFunction, panel: FilePanel): string {
+  return t("panels.file.filePanels.option", {
+    title: filePanelTitle(t, panel),
+    owner: panel.builtin ? t("panels.file.filePanels.builtin.owner") : panel.plugin.id,
+  });
+}
+
+/** ".md" for an extension key, "Dockerfile" for a filename key. */
+export function filePanelSelectorLabel(selectorKey: string): string {
+  const selector = parseFilePanelSelectorKey(selectorKey);
+  return selector.kind === "name" ? selector.value : `.${selector.value}`;
+}
+
+/** "Open .md files with" for an extension key, "Open Dockerfile with" for a filename key. */
+export function filePanelPickerTitle(t: TFunction, selectorKey: string): string {
+  const selector = parseFilePanelSelectorKey(selectorKey);
+  return selector.kind === "name"
+    ? t("panels.file.filePanels.pickerTitleFilename", { filename: selector.value })
+    : t("panels.file.filePanels.pickerTitleExtension", { extension: selector.value });
+}
+
+/** "Always use for .md", "Always use for Dockerfile". */
+export function filePanelAlwaysUseLabel(t: TFunction, selectorKey: string): string {
+  const selector = parseFilePanelSelectorKey(selectorKey);
+  return selector.kind === "name"
+    ? t("panels.file.filePanels.alwaysUseFilename", { filename: selector.value })
+    : t("panels.file.filePanels.alwaysUseExtension", { extension: selector.value });
+}

packages/app/src/file-panels/choice/registry.ts

@@ -0,0 +1,42 @@
+import {
+  buildPanelInstanceKey,
+  type PanelInstanceIdentity,
+} from "@/panels/panel-instance-attributes";
+import type { FilePanel } from "../panels";
+import type { FilePanelChoiceModel } from "./model";
+
+/**
+ * The open file tabs' choice models, so tab chrome outside the pane (the tab's context menu)
+ * reads and drives the same choice the pane renders.
+ */
+const models = new Map<string, FilePanelChoiceModel<FilePanel>>();
+const listeners = new Set<() => void>();
+
+export function registerFilePanelChoice(
+  identity: PanelInstanceIdentity,
+  model: FilePanelChoiceModel<FilePanel>,
+): () => void {
+  const key = buildPanelInstanceKey(identity);
+  models.set(key, model);
+  notify();
+  return () => {
+    if (models.get(key) !== model) return;
+    models.delete(key);
+    notify();
+  };
+}
+
+export function getFilePanelChoice(
+  identity: PanelInstanceIdentity,
+): FilePanelChoiceModel<FilePanel> | null {
+  return models.get(buildPanelInstanceKey(identity)) ?? null;
+}
+
+export function subscribeFilePanelChoices(listener: () => void): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
+
+function notify(): void {
+  for (const listener of listeners) listener();
+}

packages/app/src/file-panels/choice/switcher-layout.test.ts

@@ -0,0 +1,31 @@
+import { describe, expect, it } from "vitest";
+import type { FilePanelOpenWithState } from "./model";
+import { filePanelSwitcherState } from "./switcher-layout";
+
+function openWith(count: number): FilePanelOpenWithState<{ id: string }> {
+  const candidates = Array.from({ length: count }, (_, index) => ({ id: `panel-${index}` }));
+  return { selectorKey: "ext:md", candidates, activePanelId: "panel-1", remembered: false };
+}
+
+describe("filePanelSwitcherState", () => {
+  it("shows nothing when the file has one panel or none", () => {
+    expect(filePanelSwitcherState(null, { compact: false })).toBeNull();
+  });
+
+  it("sets up to three panels side by side and more behind a menu", () => {
+    const wide = { compact: false };
+    expect(filePanelSwitcherState(openWith(2), wide)?.layout).toBe("segmented");
+    expect(filePanelSwitcherState(openWith(3), wide)?.layout).toBe("segmented");
+    expect(filePanelSwitcherState(openWith(4), wide)).toMatchObject({
+      layout: "menu",
+      activePanelId: "panel-1",
+      candidates: openWith(4).candidates,
+    });
+  });
+
+  it("sets two panels side by side on a compact screen and more behind a menu", () => {
+    const compact = { compact: true };
+    expect(filePanelSwitcherState(openWith(2), compact)?.layout).toBe("segmented");
+    expect(filePanelSwitcherState(openWith(3), compact)?.layout).toBe("menu");
+  });
+});

packages/app/src/file-panels/choice/switcher-layout.ts

@@ -0,0 +1,24 @@
+import type { FilePanelOpenWithState } from "./model";
+
+/** Up to this many panels sit side by side in the bar; more go behind a menu. */
+const SEGMENTED_PANEL_LIMIT = { wide: 3, compact: 2 };
+
+export interface FilePanelSwitcherState<Candidate> {
+  layout: "segmented" | "menu";
+  candidates: readonly Candidate[];
+  activePanelId: string;
+}
+
+/** The bar's panel switcher for a tab's choice; null when the file has one panel or none. */
+export function filePanelSwitcherState<Candidate>(
+  openWith: FilePanelOpenWithState<Candidate> | null,
+  { compact }: { compact: boolean },
+): FilePanelSwitcherState<Candidate> | null {
+  if (!openWith) return null;
+  const limit = compact ? SEGMENTED_PANEL_LIMIT.compact : SEGMENTED_PANEL_LIMIT.wide;
+  return {
+    layout: openWith.candidates.length > limit ? "menu" : "segmented",
+    candidates: openWith.candidates,
+    activePanelId: openWith.activePanelId,
+  };
+}

packages/app/src/file-panels/choice/switcher.tsx

@@ -0,0 +1,138 @@
+import { useCallback, useMemo } from "react";
+import { Text } from "react-native";
+import { useTranslation } from "react-i18next";
+import { withUnistyles } from "react-native-unistyles";
+import { ChevronDown } from "lucide-react-native";
+import {
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuTrigger,
+} from "@/components/ui/dropdown-menu";
+import { extraMutedIconColorMapping } from "@/components/ui/icon-button-chrome";
+import { MenuItem } from "@/components/ui/menu";
+import { SegmentedControl } from "@/components/ui/segmented-control";
+import {
+  ToolbarLabelTriggerIcon,
+  isToolbarLabelTriggerHighlighted,
+  toolbarLabelTriggerStyle,
+  toolbarLabelTriggerTextStyle,
+} from "@/components/ui/toolbar-label-trigger";
+import { useIsCompactFormFactor } from "@/constants/layout";
+import { PluginIconView } from "@/plugins/icons";
+import type { Theme } from "@/styles/theme";
+import type { FilePanel } from "../panels";
+import { useFilePanelChoiceSnapshot, type FilePanelChoice } from "./hook";
+import { filePanelIcon, filePanelTitle } from "./presentation";
+import { filePanelSwitcherState, type FilePanelSwitcherState } from "./switcher-layout";
+
+const ThemedChevronDown = withUnistyles(ChevronDown);
+const ThemedPanelIcon = withUnistyles(PluginIconView);
+const mutedIconMapping = (theme: Theme) => ({ color: theme.colors.foregroundMuted });
+
+/** The file bar's panel switcher. Renders nothing unless the file has more than one panel. */
+export function FilePanelSwitcher({ choice }: { choice: FilePanelChoice }) {
+  const { openWith } = useFilePanelChoiceSnapshot(choice);
+  const compact = useIsCompactFormFactor();
+  const switcher = filePanelSwitcherState(openWith, { compact });
+  const select = useCallback((panelId: string) => choice.openWith(panelId), [choice]);
+  if (!switcher) return null;
+  return switcher.layout === "segmented" ? (
+    <SegmentedSwitcher switcher={switcher} onSelect={select} />
+  ) : (
+    <MenuSwitcher switcher={switcher} onSelect={select} />
+  );
+}
+
+interface SwitcherProps {
+  switcher: FilePanelSwitcherState<FilePanel>;
+  onSelect(panelId: string): void;
+}
+
+function SegmentedSwitcher({ switcher, onSelect }: SwitcherProps) {
+  const { t } = useTranslation();
+  const options = useMemo(
+    () =>
+      switcher.candidates.map((panel) => ({
+        value: panel.id,
+        label: filePanelTitle(t, panel),
+        testID: `file-panel-switcher-${panel.id}`,
+      })),
+    [switcher.candidates, t],
+  );
+  return (
+    <SegmentedControl
+      size="xs"
+      value={switcher.activePanelId}
+      onValueChange={onSelect}
+      options={options}
+      testID="file-panel-switcher"
+    />
+  );
+}
+
+function MenuSwitcher({ switcher, onSelect }: SwitcherProps) {
+  const { t } = useTranslation();
+  const active = switcher.candidates.find((panel) => panel.id === switcher.activePanelId);
+  const activeTitle = active ? filePanelTitle(t, active) : "";
+  return (
+    <DropdownMenu>
+      <DropdownMenuTrigger
+        style={toolbarLabelTriggerStyle}
+        accessibilityRole="button"
+        accessibilityLabel={t("panels.file.filePanels.openWith")}
+        testID="file-panel-switcher"
+      >
+        {(state) => (
+          <>
+            <Text
+              style={toolbarLabelTriggerTextStyle(isToolbarLabelTriggerHighlighted(state))}
+              numberOfLines={1}
+            >
+              {activeTitle}
+            </Text>
+            <ToolbarLabelTriggerIcon>
+              <ThemedChevronDown size={12} uniProps={extraMutedIconColorMapping} />
+            </ToolbarLabelTriggerIcon>
+          </>
+        )}
+      </DropdownMenuTrigger>
+      <DropdownMenuContent align="end" width={220} testID="file-panel-switcher-menu">
+        {switcher.candidates.map((panel) => (
+          <SwitcherMenuItem
+            key={panel.id}
+            panel={panel}
+            selected={panel.id === switcher.activePanelId}
+            onSelect={onSelect}
+          />
+        ))}
+      </DropdownMenuContent>
+    </DropdownMenu>
+  );
+}
+
+function SwitcherMenuItem({
+  panel,
+  selected,
+  onSelect,
+}: {
+  panel: FilePanel;
+  selected: boolean;
+  onSelect(panelId: string): void;
+}) {
+  const { t } = useTranslation();
+  const handleSelect = useCallback(() => onSelect(panel.id), [onSelect, panel.id]);
+  const leading = useMemo(
+    () => <ThemedPanelIcon icon={filePanelIcon(panel)} size={16} uniProps={mutedIconMapping} />,
+    [panel],
+  );
+  return (
+    <MenuItem
+      selected={selected}
+      leading={leading}
+      onSelect={handleSelect}
+      testID={`file-panel-switcher-${panel.id}`}
+    >
+      {filePanelTitle(t, panel)}
+    </MenuItem>
+  );
+}

packages/app/src/file-panels/document-frame/index.tsx

@@ -0,0 +1,98 @@
+import { useCallback, useMemo, useRef } from "react";
+import { Platform, Text, View } from "react-native";
+import { WebView } from "react-native-webview";
+import { StyleSheet } from "react-native-unistyles";
+import { useTranslation } from "react-i18next";
+
+const frameStyle = { flex: 1, backgroundColor: "white" };
+const originWhitelist = ["*"];
+
+/** What Android's WebView shows inline. It has no viewer for PDF or other documents. */
+const ANDROID_INLINE_EXTENSIONS = new Set([
+  "html",
+  "htm",
+  "xhtml",
+  "xml",
+  "svg",
+  "txt",
+  "json",
+  "png",
+  "jpg",
+  "jpeg",
+  "gif",
+  "webp",
+  "bmp",
+  "avif",
+]);
+
+export function DocumentFrame({ url, testID }: { url: string; testID?: string }) {
+  const source = useMemo(() => ({ uri: url }), [url]);
+  const loaded = useRef<string | null>(null);
+  const allowDocument = useCallback(
+    (request: { url: string }) => {
+      if (!url.startsWith("file:") || request.url !== url || loaded.current === url) return false;
+      loaded.current = url;
+      return true;
+    },
+    [url],
+  );
+  if (!url.startsWith("file:")) return null;
+  // The host names a file URL after the file, so its extension is the document's type.
+  const extension = urlExtension(url);
+  if (Platform.OS === "android" && !ANDROID_INLINE_EXTENSIONS.has(extension)) {
+    return <UnsupportedDocument extension={extension} testID={testID} />;
+  }
+  return (
+    <WebView
+      testID={testID}
+      style={frameStyle}
+      source={source}
+      originWhitelist={originWhitelist}
+      onShouldStartLoadWithRequest={allowDocument}
+      javaScriptEnabled={false}
+      setSupportMultipleWindows={false}
+      javaScriptCanOpenWindowsAutomatically={false}
+      domStorageEnabled={false}
+      thirdPartyCookiesEnabled={false}
+      cacheEnabled={false}
+      incognito
+      allowFileAccess
+      allowFileAccessFromFileURLs={false}
+      allowUniversalAccessFromFileURLs={false}
+      allowingReadAccessToURL={url}
+    />
+  );
+}
+
+function UnsupportedDocument({ extension, testID }: { extension: string; testID?: string }) {
+  const { t } = useTranslation();
+  return (
+    <View style={styles.centerState} testID={testID}>
+      <Text style={styles.mutedText}>
+        {t("panels.file.documentUnsupported", { type: extension.toUpperCase() })}
+      </Text>
+    </View>
+  );
+}
+
+function urlExtension(url: string): string {
+  const path = url.split(/[?#]/)[0];
+  const name = path.slice(path.lastIndexOf("/") + 1);
+  const dot = name.lastIndexOf(".");
+  return dot < 0 ? "" : name.slice(dot + 1).toLowerCase();
+}
+
+const styles = StyleSheet.create((theme) => ({
+  centerState: {
+    flex: 1,
+    alignItems: "center",
+    justifyContent: "center",
+    padding: theme.spacing[4],
+    backgroundColor: theme.colors.surface0,
+  },
+  mutedText: {
+    color: theme.colors.foregroundMuted,
+    fontSize: theme.fontSize.base,
+    textAlign: "center",
+  },
+}));

packages/app/src/file-panels/document-frame/index.web.tsx

@@ -0,0 +1,41 @@
+import { useEffect, useState } from "react";
+import { documentFrameSandbox } from "./sandbox";
+
+const frameStyle = { flex: 1, minHeight: 0, border: "none", backgroundColor: "white" } as const;
+
+interface ResolvedDocument {
+  url: string;
+  sandbox: string | null;
+}
+
+export function DocumentFrame({ url, testID }: { url: string; testID?: string }) {
+  const [document, setDocument] = useState<ResolvedDocument | null>(null);
+
+  useEffect(() => {
+    if (!url.startsWith("blob:")) return;
+    const lifetime = new AbortController();
+    void fetch(url, { signal: lifetime.signal })
+      .then(async (response) => {
+        const sandbox = documentFrameSandbox(response.headers.get("content-type"));
+        await response.body?.cancel();
+        if (!lifetime.signal.aborted) setDocument({ url, sandbox });
+        return undefined;
+      })
+      .catch(() => {
+        if (!lifetime.signal.aborted) setDocument({ url, sandbox: "" });
+      });
+    return () => lifetime.abort();
+  }, [url]);
+
+  if (!url.startsWith("blob:") || document?.url !== url) return null;
+  return (
+    <iframe
+      title="Document preview"
+      data-testid={testID}
+      src={url}
+      sandbox={document.sandbox ?? undefined}
+      referrerPolicy="no-referrer"
+      style={frameStyle}
+    />
+  );
+}

packages/app/src/file-panels/document-frame/sandbox.test.ts

@@ -0,0 +1,16 @@
+import { describe, expect, it } from "vitest";
+import { documentFrameSandbox } from "./sandbox";
+
+describe("document frame sandbox", () => {
+  it("lets the browser's PDF viewer render PDF documents", () => {
+    expect(documentFrameSandbox("application/pdf")).toBeNull();
+    expect(documentFrameSandbox("Application/PDF; charset=binary")).toBeNull();
+  });
+
+  it.each(["text/html", "application/octet-stream", "unknown", "", null, undefined])(
+    "keeps %s fully sandboxed",
+    (mediaType) => {
+      expect(documentFrameSandbox(mediaType)).toBe("");
+    },
+  );
+});

packages/app/src/file-panels/document-frame/sandbox.ts

@@ -0,0 +1,9 @@
+/**
+ * Chromium refuses to run its PDF viewer in a sandboxed frame, regardless of tokens.
+ * The viewer is a browser component, not page script. The host sets the blob's type from
+ * the daemon's MIME type, so HTML bytes labeled PDF fail to parse in the viewer rather
+ * than executing. HTML and every other media type retain the full sandbox.
+ */
+export function documentFrameSandbox(mediaType: string | null | undefined): string | null {
+  return mediaType?.split(";")[0].trim().toLowerCase() === "application/pdf" ? null : "";
+}

packages/app/src/file-panels/file/daemon-session.ts

@@ -0,0 +1,115 @@
+import type { DaemonClient, FileReadResult } from "@getpaseo/client/internal/daemon-client";
+import type { FileVersion } from "@getpaseo/protocol/messages";
+import {
+  persistAttachmentFromBytes,
+  releaseAttachmentPreviewUrl,
+  resolveAttachmentPreviewUrl,
+} from "@/attachments/service";
+import { createPreviewAttachmentId, getFileNameFromPath } from "@/attachments/utils";
+import type { FileKind, FileObservation, FileSession } from "./handle";
+
+export interface DaemonFileFeatures {
+  // COMPAT(workspaceFileEditing): added in v0.2.0, remove after 2027-01-18 once daemon floor >= v0.2.0.
+  workspaceFileEditing: boolean;
+  // COMPAT(fileByteWrites): added in v0.13.0, remove gate after 2027-04-20.
+  fileByteWrites: boolean;
+}
+
+/** A file session over a daemon connection. */
+export function createDaemonFileSession(
+  client: DaemonClient,
+  features: DaemonFileFeatures,
+): FileSession {
+  return {
+    async observe(target, onObservation) {
+      if (!features.workspaceFileEditing) {
+        // COMPAT(workspaceFileEditing): the host cannot observe files; its read is the stat.
+        return {
+          initial: statFromRead(await client.readFile(target.cwd, target.path)),
+          unsubscribe() {},
+        };
+      }
+      let kind: { kind: FileKind; mimeType: string } | null = null;
+      const classify = (version: FileVersion): FileObservation => {
+        if (version.status !== "ready") return version;
+        if (version.kind && version.mimeType) {
+          kind = { kind: version.kind, mimeType: version.mimeType };
+        }
+        // COMPAT(fileVersionKind): added in v0.13.0, remove after 2027-04-20. Older daemons
+        // classify a file only when reading it; the first read's kind stands for later versions.
+        if (!kind) return { ...version, status: "error", error: "The file has no kind." };
+        return { ...version, ...kind };
+      };
+      const subscription = await client.subscribeFile(target, (version) =>
+        onObservation(classify(version)),
+      );
+      const initial = subscription.initial;
+      if (initial.status === "ready" && !initial.kind) {
+        // COMPAT(fileVersionKind): see above.
+        const read = statFromRead(await client.readFile(target.cwd, target.path));
+        kind = { kind: read.kind, mimeType: read.mimeType };
+      }
+      return {
+        initial: classify(initial),
+        unsubscribe() {
+          void subscription.unsubscribe();
+        },
+      };
+    },
+    async read(target) {
+      return client.readFile(target.cwd, target.path);
+    },
+    async write({ target, content, ...expected }) {
+      if (!features.workspaceFileEditing) throw new Error("Update the host to edit files.");
+      if (typeof content === "string") {
+        return client.writeFile({ ...target, content, ...expected });
+      }
+      if (!features.fileByteWrites) throw new Error("Update the host to write binary files.");
+      return client.writeFile({
+        ...target,
+        content: bytesToBase64(content),
+        contentEncoding: "base64",
+        ...expected,
+      });
+    },
+    async createUrl({ target, bytes, mimeType }) {
+      const attachment = await persistAttachmentFromBytes({
+        id: createPreviewAttachmentId({
+          mimeType,
+          path: `${target.cwd}/${target.path}`,
+          contentLength: bytes.byteLength,
+          contentKey: String(Date.now()),
+        }),
+        bytes,
+        mimeType,
+        fileName: getFileNameFromPath(target.path),
+      });
+      const url = await resolveAttachmentPreviewUrl(attachment);
+      return {
+        url,
+        release() {
+          void releaseAttachmentPreviewUrl({ attachment, url });
+        },
+      };
+    },
+  };
+}
+
+function statFromRead(file: FileReadResult): Extract<FileObservation, { status: "ready" }> {
+  return {
+    status: "ready",
+    size: file.size,
+    modifiedAt: file.modifiedAt,
+    revision: file.revision,
+    kind: file.kind,
+    mimeType: file.mime,
+  };
+}
+
+function bytesToBase64(bytes: Uint8Array): string {
+  let binary = "";
+  for (let index = 0; index < bytes.length; index += 0x8000) {
+    binary += String.fromCharCode(...bytes.subarray(index, index + 0x8000));
+  }
+  return btoa(binary);
+}

packages/app/src/file-panels/file/handle.test.ts

@@ -0,0 +1,195 @@
+import {
+  PluginFileConflictError,
+  PluginFileDeletedError,
+  type PluginFileEvent,
+} from "@getpaseo/plugin/client";
+import { describe, expect, it } from "vitest";
+import { FileHandle } from "./handle";
+import { InMemoryFileSession } from "./testing";
+
+async function openFile(content: string | Uint8Array = "first\n") {
+  const session = new InMemoryFileSession();
+  session.put("notes.md", content);
+  const handle = new FileHandle(session, { cwd: "/repo", path: "notes.md" }, "/repo/notes.md");
+  handle.setObserving(true);
+  await settle();
+  const events: PluginFileEvent["type"][] = [];
+  handle.file.watch((event) => events.push(event.type));
+  return { session, handle, file: handle.file, events };
+}
+
+function settle(): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, 0));
+}
+
+describe("FileHandle", () => {
+  it("describes the file from its stat before anything reads it", async () => {
+    const { handle, file } = await openFile("# Notes\n");
+
+    expect(handle.getSnapshot()).toMatchObject({ status: "ready", kind: "text", size: 8 });
+    expect([file.path, file.name, file.extension, file.mimeType, file.size]).toEqual([
+      "/repo/notes.md",
+      "notes.md",
+      "md",
+      "text/plain",
+      8,
+    ]);
+  });
+
+  it("writes over the version it read and refreshes the stat", async () => {
+    const { session, file, events } = await openFile();
+
+    expect(await file.readText()).toBe("first\n");
+    await file.writeText("second, longer\n");
+
+    expect(session.text("notes.md")).toBe("second, longer\n");
+    expect(file.size).toBe(15);
+    expect(events).toEqual([]);
+  });
+
+  it("rejects a write after an external change unless forced", async () => {
+    const { session, file, events } = await openFile();
+    await file.readText();
+
+    session.put("notes.md", "external\n");
+    await expect(file.writeText("mine\n")).rejects.toBeInstanceOf(PluginFileConflictError);
+    expect(session.text("notes.md")).toBe("external\n");
+
+    await file.writeText("mine\n", { force: true });
+    expect(session.text("notes.md")).toBe("mine\n");
+    expect(events).toEqual(["changed"]);
+  });
+
+  it("rejects a write over a deleted file it has not observed yet", async () => {
+    const { session, handle, file } = await openFile();
+    await file.readText();
+    handle.setObserving(false);
+    session.remove("notes.md");
+
+    await expect(file.writeText("mine\n")).rejects.toBeInstanceOf(PluginFileDeletedError);
+    await expect(file.writeText("mine\n", { force: true })).rejects.toBeInstanceOf(
+      PluginFileDeletedError,
+    );
+  });
+
+  it("forces over a change it has not observed yet", async () => {
+    const { session, handle, file } = await openFile();
+    await file.readText();
+    handle.setObserving(false);
+    session.put("notes.md", "unobserved\n");
+
+    await file.writeText("mine\n", { force: true });
+
+    expect(session.text("notes.md")).toBe("mine\n");
+  });
+
+  it("keeps a byte order mark it read", async () => {
+    const { session, file } = await openFile(
+      new Uint8Array([0xef, 0xbb, 0xbf, ...new TextEncoder().encode("bom\r\n")]),
+    );
+
+    expect(await file.readText()).toBe("bom\r\n");
+    await file.writeText("saved\r\n");
+
+    expect(session.text("notes.md")).toBe("saved\r\n");
+  });
+
+  it("tells watchers about each external version once, and about deletion", async () => {
+    const { session, file, events } = await openFile();
+
+    session.put("notes.md", "external\n");
+    await file.readText();
+    session.remove("notes.md");
+    session.remove("notes.md");
+    await settle();
+    session.put("notes.md", "restored\n");
+
+    expect(events).toEqual(["changed", "deleted", "changed"]);
+  });
+
+  it("keeps the stat of a deleted file, so its panel stays mounted", async () => {
+    const { session, handle } = await openFile();
+
+    session.remove("notes.md");
+    await settle();
+
+    expect(handle.getSnapshot()).toMatchObject({ status: "ready", kind: "text" });
+  });
+
+  it("does not report a deletion when the file is back before a read confirms it", async () => {
+    const { session, events } = await openFile();
+
+    session.remove("notes.md");
+    session.put("notes.md", "first\n");
+    await settle();
+
+    expect(events).toEqual(["changed"]);
+  });
+
+  it("reports what changed while the tab was off screen", async () => {
+    const { session, handle, events } = await openFile();
+
+    handle.setObserving(false);
+    session.put("notes.md", "while hidden\n");
+    expect(events).toEqual([]);
+    handle.setObserving(true);
+    await settle();
+
+    expect(events).toEqual(["changed"]);
+    expect(session.observerCount()).toBe(1);
+  });
+
+  it("reads after its own pending writes", async () => {
+    const { file } = await openFile();
+    await file.readText();
+
+    const write = file.writeText("flushed\n");
+    const read = file.readText();
+
+    await write;
+    expect(await read).toBe("flushed\n");
+  });
+
+  it("holds writes while the tab asks to discard them, and drops them when it closes", async () => {
+    const { session, handle, file } = await openFile();
+    await file.readText();
+
+    const resume = handle.holdWrites();
+    const kept = file.writeText("kept\n");
+    await settle();
+    expect(session.text("notes.md")).toBe("first\n");
+    resume();
+    await kept;
+    expect(session.text("notes.md")).toBe("kept\n");
+
+    handle.holdWrites();
+    const dropped = file.writeText("dropped\n");
+    handle.dispose();
+    await expect(dropped).rejects.toThrow("The file tab was closed.");
+    expect(session.text("notes.md")).toBe("kept\n");
+  });
+
+  it("owns one URL per version and releases it when replaced or closed", async () => {
+    const { session, handle, file } = await openFile();
+
+    const first = await file.url();
+    expect(await file.url()).toBe(first);
+    session.put("notes.md", "changed\n");
+    const second = await file.url();
+
+    expect(second).not.toBe(first);
+    expect(session.createdUrls).toEqual([first, second]);
+    expect(session.releasedUrls).toEqual([first]);
+    handle.dispose();
+    expect(session.releasedUrls).toEqual([first, second]);
+  });
+
+  it("writes bytes", async () => {
+    const { session, file } = await openFile();
+    await file.readBytes();
+
+    await file.writeBytes(new Uint8Array([1, 2, 3]));
+
+    expect(session.writes).toEqual(["bytes:3"]);
+  });
+});

packages/app/src/file-panels/file/handle.ts

@@ -0,0 +1,413 @@
+import {
+  PluginFileConflictError,
+  PluginFileDeletedError,
+  type PluginFile,
+  type PluginFileEvent,
+  type PluginFileWriteOptions,
+} from "@getpaseo/plugin/client";
+import type { FileVersion, FileWriteResult } from "@getpaseo/protocol/messages";
+import { decodeUtf8 } from "@/utils/decode-utf8";
+
+export interface FileTarget {
+  cwd: string;
+  path: string;
+}
+
+export type FileKind = "text" | "image" | "binary";
+
+/** A version the session has classified, so a panel can be chosen before the file is read. */
+export interface FileStat {
+  status: "ready";
+  size: number;
+  modifiedAt: string;
+  revision?: string;
+  kind: FileKind;
+  mimeType: string;
+}
+
+export type FileObservation =
+  | FileStat
+  | Extract<FileVersion, { status: "missing" }>
+  | Extract<FileVersion, { status: "error" }>;
+
+export interface FileContents {
+  bytes: Uint8Array;
+  size: number;
+  modifiedAt: string;
+  revision?: string;
+}
+
+/** What a handle needs from the host. The daemon implementation lives in `./daemon-session`. */
+export interface FileSession {
+  observe(
+    target: FileTarget,
+    onObservation: (observation: FileObservation) => void,
+  ): Promise<{ initial: FileObservation; unsubscribe(): void }>;
+  read(target: FileTarget): Promise<FileContents>;
+  write(input: {
+    target: FileTarget;
+    content: string | Uint8Array;
+    expectedModifiedAt: string;
+    expectedRevision?: string;
+  }): Promise<FileWriteResult>;
+  createUrl(input: { target: FileTarget; bytes: Uint8Array; mimeType: string }): Promise<{
+    url: string;
+    release(): void;
+  }>;
+}
+
+export type FileHandleSnapshot =
+  | { status: "loading" }
+  | FileStat
+  | { status: "missing" }
+  | { status: "error"; error: string };
+
+interface Version {
+  size: number;
+  modifiedAt: string;
+  revision?: string;
+}
+
+/**
+ * One file tab target's file: its stat for choosing a panel, and the `PluginFile` every panel
+ * reads and writes through.
+ *
+ * The handle remembers the version it last read or wrote, and writes only over that version.
+ * Changes on disk reach `watch` listeners once per version; versions this handle read or wrote
+ * itself do not. Reads wait for this handle's writes, so a panel that mounts while another flushes
+ * reads the flushed file. Writes run one at a time, and wait while the tab holds them.
+ *
+ * Once the file has a stat, the snapshot keeps it: the mounted panel keeps what it shows, and
+ * learns about a deletion from `watch`. A deletion is reported only after a read confirms it, so a
+ * program that removes the file and writes it back does not look like one.
+ */
+export class FileHandle {
+  readonly file: PluginFile;
+  private readonly listeners = new Set<() => void>();
+  private readonly watchers = new Set<(event: PluginFileEvent) => void>();
+  private snapshot: FileHandleSnapshot = { status: "loading" };
+  private stat: FileStat | null = null;
+  private latest: FileObservation | null = null;
+  private base: Version | null = null;
+  /** Versions this handle has read, written, or told watchers about. */
+  private readonly seen = new Set<string>();
+  private deleted = false;
+  private confirmingDeletion = false;
+  private hasBom = false;
+  private writes: Promise<unknown> = Promise.resolve();
+  private writing = 0;
+  private holds = 0;
+  private releaseHold: (() => void) | null = null;
+  private held: Promise<void> | null = null;
+  private observing: { generation: number; unsubscribe: (() => void) | null } | null = null;
+  private generation = 0;
+  private currentUrl: { key: string; url: Promise<string>; release: () => void } | null = null;
+  private disposed = false;
+
+  constructor(
+    private readonly session: FileSession,
+    private readonly target: FileTarget,
+    absolutePath: string,
+  ) {
+    const stat = () => this.stat;
+    const name = absolutePath.split(/[\\/]/).pop() ?? "";
+    const dot = name.lastIndexOf(".");
+    this.file = {
+      path: absolutePath,
+      name,
+      extension: dot < 0 ? "" : name.slice(dot + 1).toLowerCase(),
+      get size() {
+        return stat()?.size ?? 0;
+      },
+      get modifiedAt() {
+        return stat()?.modifiedAt ?? "";
+      },
+      get mimeType() {
+        return stat()?.mimeType ?? "application/octet-stream";
+      },
+      readText: () => this.readText(),
+      readBytes: () => this.readBytes(),
+      url: () => this.url(),
+      writeText: (text, options) => this.writeText(text, options),
+      writeBytes: (bytes, options) => this.write(bytes, options),
+      watch: (listener) => {
+        this.watchers.add(listener);
+        return () => this.watchers.delete(listener);
+      },
+    };
+  }
+
+  subscribe = (listener: () => void): (() => void) => {
+    this.listeners.add(listener);
+    return () => this.listeners.delete(listener);
+  };
+
+  getSnapshot = (): FileHandleSnapshot => this.snapshot;
+
+  /** Observes the file while the tab is on screen. Coming back reports what changed meanwhile. */
+  setObserving(observing: boolean): void {
+    if (this.disposed || observing === (this.observing !== null)) return;
+    if (!observing) {
+      this.stopObserving();
+      return;
+    }
+    const generation = ++this.generation;
+    this.observing = { generation, unsubscribe: null };
+    void this.observe(generation);
+  }
+
+  private async observe(generation: number): Promise<void> {
+    let subscription: Awaited<ReturnType<FileSession["observe"]>>;
+    try {
+      subscription = await this.session.observe(this.target, (observation) => {
+        if (this.observing?.generation === generation) this.receive(observation);
+      });
+    } catch (error) {
+      if (this.observing?.generation !== generation) return;
+      this.observing = null;
+      this.setSnapshot({ status: "error", error: errorMessage(error) });
+      return;
+    }
+    if (this.observing?.generation !== generation) {
+      subscription.unsubscribe();
+      return;
+    }
+    this.observing.unsubscribe = subscription.unsubscribe;
+    this.receive(subscription.initial);
+  }
+
+  /** Observes again after a failure. */
+  retry = (): void => {
+    this.stopObserving();
+    this.setObserving(true);
+  };
+
+  /**
+   * Holds this file's writes while the tab asks whether to discard unsaved changes. The returned
+   * function lets them run; closing the tab disposes the handle, which drops them.
+   */
+  holdWrites = (): (() => void) => {
+    this.holds += 1;
+    if (this.holds === 1) {
+      this.held = new Promise((resolve) => {
+        this.releaseHold = resolve;
+      });
+    }
+    let resumed = false;
+    return () => {
+      if (resumed) return;
+      resumed = true;
+      this.holds -= 1;
+      if (this.holds > 0) return;
+      this.releaseHold?.();
+      this.releaseHold = null;
+      this.held = null;
+    };
+  };
+
+  dispose(): void {
+    if (this.disposed) return;
+    this.disposed = true;
+    this.stopObserving();
+    this.currentUrl?.release();
+    this.currentUrl = null;
+    this.releaseHold?.();
+    this.listeners.clear();
+    this.watchers.clear();
+  }
+
+  private stopObserving(): void {
+    this.observing?.unsubscribe?.();
+    this.observing = null;
+  }
+
+  private receive(observation: FileObservation): void {
+    if (this.disposed) return;
+    this.latest = observation;
+    if (observation.status === "ready") {
+      this.stat = observation;
+      if (!this.base) this.adopt(observation);
+      this.setSnapshot(observation);
+    } else if (!this.stat) {
+      this.setSnapshot(
+        observation.status === "missing"
+          ? { status: "missing" }
+          : { status: "error", error: observation.error },
+      );
+    }
+    this.notifyChange(observation);
+  }
+
+  /** Tells watchers about a disk version this handle did not read or write itself. */
+  private notifyChange(observation: FileObservation): void {
+    if (this.writing > 0 || observation.status === "error") return;
+    if (observation.status === "missing") {
+      if (!this.deleted) void this.confirmDeletion();
+      return;
+    }
+    this.notifyVersion(observation);
+  }
+
+  private notifyVersion(version: Version): void {
+    const key = versionKey(version);
+    const restored = this.deleted;
+    this.deleted = false;
+    if (this.seen.has(key) && !restored) return;
+    this.seen.add(key);
+    this.emit({ type: "changed" });
+  }
+
+  private async confirmDeletion(): Promise<void> {
+    if (this.confirmingDeletion) return;
+    this.confirmingDeletion = true;
+    let contents: FileContents | null = null;
+    try {
+      contents = await this.session.read(this.target);
+    } catch {
+      // The read failing is the confirmation.
+    } finally {
+      this.confirmingDeletion = false;
+    }
+    if (this.disposed || this.writing > 0 || this.deleted) return;
+    if (contents) {
+      this.notifyVersion(contents);
+      return;
+    }
+    if (this.latest?.status !== "missing") return;
+    this.deleted = true;
+    this.emit({ type: "deleted" });
+  }
+
+  private emit(event: PluginFileEvent): void {
+    for (const watcher of this.watchers) watcher(event);
+  }
+
+  private async readContents(): Promise<FileContents> {
+    this.assertOpen();
+    await this.writes;
+    const contents = await this.session.read(this.target);
+    this.assertOpen();
+    this.adopt(contents);
+    return contents;
+  }
+
+  private async readText(): Promise<string> {
+    const { bytes } = await this.readContents();
+    this.hasBom = bytes[0] === 0xef && bytes[1] === 0xbb && bytes[2] === 0xbf;
+    return decodeUtf8(bytes);
+  }
+
+  private async readBytes(): Promise<Uint8Array> {
+    return (await this.readContents()).bytes;
+  }
+
+  private url(): Promise<string> {
+    const current = this.currentUrl;
+    if (current && this.stat && current.key === versionKey(this.stat)) return current.url;
+    return this.createUrl();
+  }
+
+  private async createUrl(): Promise<string> {
+    const contents = await this.readContents();
+    const key = versionKey(contents);
+    if (this.currentUrl?.key === key) return this.currentUrl.url;
+    const created = await this.session.createUrl({
+      target: this.target,
+      bytes: contents.bytes,
+      mimeType: this.file.mimeType,
+    });
+    if (this.disposed) {
+      created.release();
+      throw new Error("The file tab was closed.");
+    }
+    this.currentUrl?.release();
+    this.currentUrl = { key, url: Promise.resolve(created.url), release: created.release };
+    return created.url;
+  }
+
+  private writeText(text: string, options?: PluginFileWriteOptions): Promise<void> {
+    return this.write(this.hasBom ? `${text}` : text, options);
+  }
+
+  private write(content: string | Uint8Array, options?: PluginFileWriteOptions): Promise<void> {
+    const write = this.writes.then(() => this.performWrite(content, options?.force === true));
+    this.writes = write.catch(() => undefined);
+    return write;
+  }
+
+  private async performWrite(content: string | Uint8Array, force: boolean): Promise<void> {
+    this.assertOpen();
+    if (this.held) await this.held;
+    this.assertOpen();
+    this.writing += 1;
+    try {
+      let expected = force ? (this.stat ?? this.base) : this.base;
+      for (let attempt = 0; ; attempt += 1) {
+        if (!expected) throw new PluginFileConflictError();
+        const result = await this.session.write({
+          target: this.target,
+          content,
+          expectedModifiedAt: expected.modifiedAt,
+          expectedRevision: expected.revision,
+        });
+        if (result.status === "written") {
+          this.adopt(result);
+          return;
+        }
+        if (result.status === "error") throw new Error(result.error);
+        const disk = result.version;
+        if (force && attempt === 0 && disk.status === "ready") {
+          expected = disk;
+          continue;
+        }
+        if (disk.status === "missing") throw new PluginFileDeletedError();
+        throw new PluginFileConflictError();
+      }
+    } finally {
+      this.writing -= 1;
+      // Observations that arrived during the write may be its own version, so they wait for it.
+      if (this.latest && !this.disposed) this.notifyChange(this.latest);
+    }
+  }
+
+  /** Records a version this handle read or wrote, so its observation does not notify. */
+  private adopt(version: Version): void {
+    this.base = { size: version.size, modifiedAt: version.modifiedAt, revision: version.revision };
+    this.seen.add(versionKey(version));
+    if (this.stat && versionKey(this.stat) !== versionKey(version)) {
+      this.stat = { ...this.stat, ...this.base };
+      this.setSnapshot(this.stat);
+    }
+  }
+
+  private assertOpen(): void {
+    if (this.disposed) throw new Error("The file tab was closed.");
+  }
+
+  private setSnapshot(snapshot: FileHandleSnapshot): void {
+    if (sameSnapshot(this.snapshot, snapshot)) return;
+    this.snapshot = snapshot;
+    for (const listener of this.listeners) listener();
+  }
+}
+
+function versionKey(version: Version): string {
+  return version.revision ?? `${version.size}:${version.modifiedAt}`;
+}
+
+function sameSnapshot(current: FileHandleSnapshot, next: FileHandleSnapshot): boolean {
+  if (current.status !== next.status) return false;
+  if (current.status === "ready" && next.status === "ready") {
+    return (
+      versionKey(current) === versionKey(next) &&
+      current.kind === next.kind &&
+      current.mimeType === next.mimeType
+    );
+  }
+  if (current.status === "error" && next.status === "error") return current.error === next.error;
+  return true;
+}
+
+function errorMessage(error: unknown): string {
+  return error instanceof Error ? error.message : String(error);
+}

packages/app/src/file-panels/file/hook.ts

@@ -0,0 +1,56 @@
+import { useEffect, useState, useSyncExternalStore } from "react";
+import { useSessionStore } from "@/stores/session-store";
+import { createDaemonFileSession } from "./daemon-session";
+import { FileHandle, type FileHandleSnapshot, type FileTarget } from "./handle";
+
+/** The tab target's file handle, observing while `observing`. Disposed when the target changes. */
+export function useFileHandle(input: {
+  serverId: string;
+  target: FileTarget | null;
+  absolutePath: string;
+  observing: boolean;
+}): FileHandle | null {
+  const { serverId, target, absolutePath, observing } = input;
+  const client = useSessionStore((state) => state.sessions[serverId]?.client ?? null);
+  // COMPAT(workspaceFileEditing): added in v0.2.0, remove after 2027-01-18 once daemon floor >= v0.2.0.
+  const workspaceFileEditing = useSessionStore(
+    (state) => state.sessions[serverId]?.serverInfo?.features?.workspaceFileEditing === true,
+  );
+  // COMPAT(fileByteWrites): added in v0.13.0, remove gate after 2027-04-20.
+  const fileByteWrites = useSessionStore(
+    (state) => state.sessions[serverId]?.serverInfo?.features?.fileByteWrites === true,
+  );
+  const cwd = target?.cwd ?? null;
+  const path = target?.path ?? null;
+  const [handle, setHandle] = useState<{ key: string; handle: FileHandle } | null>(null);
+  const key = client && cwd && path ? `${cwd}:${path}` : null;
+
+  useEffect(() => {
+    if (!client || !cwd || !path) {
+      setHandle(null);
+      return;
+    }
+    const session = createDaemonFileSession(client, { workspaceFileEditing, fileByteWrites });
+    const next = new FileHandle(session, { cwd, path }, absolutePath);
+    setHandle({ key: `${cwd}:${path}`, handle: next });
+    return () => next.dispose();
+  }, [absolutePath, client, cwd, fileByteWrites, path, workspaceFileEditing]);
+
+  const current = handle?.key === key ? handle.handle : null;
+  useEffect(() => {
+    current?.setObserving(observing);
+  }, [current, observing]);
+  return current;
+}
+
+const LOADING: FileHandleSnapshot = { status: "loading" };
+const subscribeNothing = () => () => {};
+const getLoading = () => LOADING;
+
+export function useFileHandleSnapshot(handle: FileHandle | null): FileHandleSnapshot {
+  return useSyncExternalStore(
+    handle?.subscribe ?? subscribeNothing,
+    handle?.getSnapshot ?? getLoading,
+    handle?.getSnapshot ?? getLoading,
+  );
+}

packages/app/src/file-panels/file/hooks.test.tsx

@@ -0,0 +1,57 @@
+// @vitest-environment jsdom
+
+import { act, renderHook, waitFor } from "@testing-library/react";
+import { PluginFileDeletedError, useFileText, useFileUrl } from "@getpaseo/plugin/client";
+import { describe, expect, it } from "vitest";
+import { FileHandle } from "./handle";
+import { InMemoryFileSession } from "./testing";
+
+function openFile(content = "first\n") {
+  const session = new InMemoryFileSession();
+  session.put("notes.md", content);
+  const handle = new FileHandle(session, { cwd: "/repo", path: "notes.md" }, "/repo/notes.md");
+  handle.setObserving(true);
+  return { session, handle, file: handle.file };
+}
+
+describe("file hooks", () => {
+  it("reads the text, then follows changes without going back to loading", async () => {
+    const { session, file } = openFile();
+    const states: string[] = [];
+    const { result } = renderHook(() => {
+      const text = useFileText(file);
+      states.push(text.status);
+      return text;
+    });
+
+    await waitFor(() => expect(result.current).toEqual({ status: "ready", text: "first\n" }));
+    act(() => session.put("notes.md", "second\n"));
+    await waitFor(() => expect(result.current).toEqual({ status: "ready", text: "second\n" }));
+
+    expect(states.lastIndexOf("loading")).toBeLessThan(states.indexOf("ready"));
+  });
+
+  it("reports a deleted file as a PluginFileDeletedError", async () => {
+    const { session, file } = openFile();
+    const { result } = renderHook(() => useFileText(file));
+    await waitFor(() => expect(result.current.status).toBe("ready"));
+
+    act(() => session.remove("notes.md"));
+
+    await waitFor(() => expect(result.current.status).toBe("error"));
+    expect(result.current.status === "error" && result.current.error).toBeInstanceOf(
+      PluginFileDeletedError,
+    );
+  });
+
+  it("resolves a URL per version and releases the old one", async () => {
+    const { session, file } = openFile();
+    const { result } = renderHook(() => useFileUrl(file));
+    await waitFor(() => expect(result.current).toEqual({ status: "ready", url: "blob:test/1" }));
+
+    act(() => session.put("notes.md", "second\n"));
+
+    await waitFor(() => expect(result.current).toEqual({ status: "ready", url: "blob:test/2" }));
+    expect(session.releasedUrls).toEqual(["blob:test/1"]);
+  });
+});

packages/app/src/file-panels/file/index.ts

@@ -0,0 +1,2 @@
+export { FileHandle, type FileHandleSnapshot, type FileStat, type FileTarget } from "./handle";
+export { useFileHandle, useFileHandleSnapshot } from "./hook";

packages/app/src/file-panels/file/testing.ts

@@ -0,0 +1,127 @@
+import type { FileWriteResult } from "@getpaseo/protocol/messages";
+import type { FileContents, FileObservation, FileSession, FileTarget } from "./handle";
+
+interface StoredFile {
+  bytes: Uint8Array;
+  revision: number;
+}
+
+/**
+ * A file session over an in-memory disk, for tests. A write delivers its own observation before
+ * it resolves, the order the daemon's watcher can produce.
+ */
+export class InMemoryFileSession implements FileSession {
+  readonly createdUrls: string[] = [];
+  readonly releasedUrls: string[] = [];
+  readonly writes: string[] = [];
+  private readonly files = new Map<string, StoredFile>();
+  private readonly observers = new Set<{
+    path: string;
+    onObservation: (observation: FileObservation) => void;
+  }>();
+  private revision = 0;
+  private urlCount = 0;
+  private nextWriteError: string | null = null;
+
+  /** The next write reports this error instead of writing. */
+  failNextWrite(error: string): void {
+    this.nextWriteError = error;
+  }
+
+  /** Writes the file as another program would. */
+  put(path: string, content: string | Uint8Array): void {
+    const bytes = typeof content === "string" ? new TextEncoder().encode(content) : content;
+    this.files.set(path, { bytes, revision: ++this.revision });
+    this.notify(path);
+  }
+
+  remove(path: string): void {
+    this.files.delete(path);
+    this.notify(path);
+  }
+
+  text(path: string): string | null {
+    const file = this.files.get(path);
+    return file ? new TextDecoder("utf-8", { ignoreBOM: true }).decode(file.bytes) : null;
+  }
+
+  observerCount(): number {
+    return this.observers.size;
+  }
+
+  async observe(target: FileTarget, onObservation: (observation: FileObservation) => void) {
+    const observer = { path: target.path, onObservation };
+    this.observers.add(observer);
+    return {
+      initial: this.observation(target.path),
+      unsubscribe: () => {
+        this.observers.delete(observer);
+      },
+    };
+  }
+
+  async read(target: FileTarget): Promise<FileContents> {
+    const file = this.files.get(target.path);
+    if (!file) throw new Error("File not found");
+    return { bytes: file.bytes, ...version(file) };
+  }
+
+  async write(input: {
+    target: FileTarget;
+    content: string | Uint8Array;
+    expectedModifiedAt: string;
+    expectedRevision?: string;
+  }): Promise<FileWriteResult> {
+    if (this.nextWriteError) {
+      const error = this.nextWriteError;
+      this.nextWriteError = null;
+      return { status: "error", error };
+    }
+    const file = this.files.get(input.target.path);
+    if (!file) {
+      return {
+        status: "conflict",
+        version: { status: "missing", cwd: "/", path: input.target.path },
+      };
+    }
+    if (input.expectedRevision !== String(file.revision)) {
+      return {
+        status: "conflict",
+        version: { status: "ready", cwd: "/", path: input.target.path, ...version(file) },
+      };
+    }
+    this.writes.push(
+      typeof input.content === "string" ? input.content : `bytes:${input.content.length}`,
+    );
+    this.put(input.target.path, input.content);
+    const written = this.files.get(input.target.path)!;
+    return { status: "written", ...version(written) };
+  }
+
+  async createUrl() {
+    const url = `blob:test/${++this.urlCount}`;
+    this.createdUrls.push(url);
+    return { url, release: () => this.releasedUrls.push(url) };
+  }
+
+  private observation(path: string): FileObservation {
+    const file = this.files.get(path);
+    if (!file) return { status: "missing", cwd: "/", path };
+    return { status: "ready", kind: "text", mimeType: "text/plain", ...version(file) };
+  }
+
+  private notify(path: string): void {
+    const observation = this.observation(path);
+    for (const observer of this.observers) {
+      if (observer.path === path) observer.onObservation(observation);
+    }
+  }
+}
+
+function version(file: StoredFile) {
+  return {
+    size: file.bytes.length,
+    modifiedAt: new Date(file.revision * 1000).toISOString(),
+    revision: String(file.revision),
+  };
+}