test(app): retain reproduction for code size lost during appearance update

* Stack workspace sheets and tighten sidebar density

- Workspace sheets stack: opening a target from a sheet covers it, Back and
  drag close only the top sheet, and the header is the sheet's drag handle.
- The workspace sheet reuses the shared sheet handle, background and header.
- Fix the shared sheet handle indicator rendering black.
- Sidebar text returns to semantic sizes; Pinned and Workspaces share one
  section header.

* Pause covered workspace sheets and mock the shared sheet handle in tests

* Export BottomSheetHandle from the browser test Gorhom stub

* Let a stacked sheet's backdrop catch taps on iOS

* Bring a revealed sheet to the top instead of duplicating it as a tab

CLAUDE.md

@@ -54,7 +54,7 @@ At the start of non-trivial work, list `docs/` and skim anything relevant to the
 | [docs/qa.md](docs/qa.md)                                             | QA evidence bar for pull requests — platform matrix, version drift, performance, UI proof                                      |
 | [docs/mobile-testing.md](docs/mobile-testing.md)                     | Maestro and mobile test workflows                                                                                              |
 | [docs/mobile-panels.md](docs/mobile-panels.md)                       | Compact left/center/right panel ownership, worklet motion, gesture revisions, and Fabric constraints                           |
-| [docs/explorer-sidebar.md](docs/explorer-sidebar.md)                 | Explorer sidebar and ordinary side-pane host contracts, lifecycle, placement, and routing preferences                          |
+| [docs/explorer-sidebar.md](docs/explorer-sidebar.md)                 | Explorer sidebar, side-pane, and compact workspace sheet host contracts, lifecycle, placement, routing preferences             |
 | [docs/ad-hoc-daemon-testing.md](docs/ad-hoc-daemon-testing.md)       | Isolated in-process daemon test harness                                                                                        |
 | [docs/browser-capture-harness.md](docs/browser-capture-harness.md)   | Real-Electron browser screenshot harness and compositor-surface gotcha                                                         |
 | [docs/android.md](docs/android.md)                                   | App variants, local/cloud builds, EAS workflows, version codes, F-Droid source builds and store metadata                       |

docs/agent-lifecycle.md

@@ -212,7 +212,7 @@ parentAgentId === thisAgent.id  AND  !archivedAt
 
 - **Provider subagents** are child executions owned by Claude, Codex, or OpenCode. They are not inserted into `AgentManager` as managed agents. Providers emit a separate descriptor and timeline stream through `agent.provider_subagents.*`; the client keeps that state outside the normal agent store and merges only the presentation rows into the track. A descriptor's optional `parentSubagentId` identifies its direct provider-subagent parent; an absent value identifies a direct child of the managed agent.
 
-Clicking either kind opens a workspace tab. A Paseo subagent tab is a normal interactive agent pane. A provider subagent tab is a read-only timeline pane with no composer, archive, detach, rewind, or fork actions. It shows its own direct children in a subagents track. Both panes use `AgentStreamView`, so message, reasoning, tool-call, and layout rendering stay identical.
+Clicking either kind opens a workspace tab. On compact layouts it opens in the [workspace sheet](explorer-sidebar.md#workspace-sheet) instead; the sheet hides the composer, and a Paseo subagent's sheet offers **Open as tab** to get it back. A Paseo subagent tab is a normal interactive agent pane. A provider subagent tab is a read-only timeline pane with no composer, archive, detach, rewind, or fork actions. It shows its own direct children in a subagents track. Both panes use `AgentStreamView`, so message, reasoning, tool-call, and layout rendering stay identical.
 
 Provider timelines use the same structural timeline item format but deliberately have a separate lifecycle and transport. A provider thread/session identifier is not a Paseo agent identifier, and closing its tab is always layout-only.
 

docs/explorer-sidebar.md

@@ -7,6 +7,7 @@ contracts.
 | ---------------- | ---------------------------- | ------------------------------------------ |
 | Explorer sidebar | Files and Changes navigation | Cmd+E shows or hides the dedicated dock    |
 | Side pane        | Ordinary workspace content   | Created and closed like any workspace pane |
+| Workspace sheet  | Compact look-ups             | Stacks tabs; each closes or becomes a tab  |
 
 ## Panel host contract
 
@@ -22,6 +23,29 @@ can move between Explorer and main panes.
 Keep panel implementations independent of either shell. `WorkspacePanelHost` owns mounting and
 retention, while each shell owns its tabs, focus, dragging, resizing, and shortcuts.
 
+## Workspace sheet
+
+On compact layouts, files and subagents open in a closable sheet over the workspace, so the tab
+switcher keeps only agents and terminals. A panel kind opts in with `compactSheet` in its manifest
+(`packages/app/src/panels/panel-manifest.ts`), and the layout store's `openTab` decides between
+sheet and tab, so callers open targets the same way on every layout. Each sheet holds one ordinary
+`WorkspaceTab`, and sheets stack: a target opened from a sheet covers it, and closing the top sheet
+(drag, Close, backdrop, or Android Back) uncovers the one below. Revealing a target that already has
+a sheet brings that sheet back to the top and closes the sheets above it, except ones holding unsaved
+work. Opening a sheet as a tab dismisses the sheets above it, since the
+tab would sit under them. The stack is not persisted.
+
+Sheets are modal and cover the whole compact column, header included. A sheet's header is its drag
+handle, because the panel scrolls on its own and content panning would fight it. Sheets render in
+the workspace tree rather than through `IsolatedBottomSheetModal`: their panels need the navigator
+and every workspace provider an ordinary pane has, and a portal drops them
+([floating-panels.md Gotcha 7](floating-panels.md#gotcha-7--a-sheet-cannot-read-context-from-its-call-site)).
+
+A sheet holding unsaved work is never implicitly displaced; only its guarded close removes it.
+Moving its tab to another host remounts the panel, and the file editor keeps unsaved text in the
+mounted view, so the move would drop it. Widening the layout is the known exception: it still moves
+the sheet's tab into a pane, and edits the autosave has not started writing are lost.
+
 ## Explorer sidebar
 
 `packages/app/src/workspace-tabs/explorer-sidebar.ts` owns show, hide, toggle, and view selection.
@@ -62,7 +86,9 @@ lifecycle.
 
 `packages/app/src/workspace-tabs/open-beside.ts` owns content opened beside the user's work. The
 layout store remembers one ordinary pane per workspace. The first side open creates a full-height
-right split around the workspace root; later side opens reuse it.
+right split around the workspace root; later side opens reuse it. Only the `split-panes` layout
+mode opens beside. Compact and single-pane layouts (touch tablets) open the same target in the main
+pane, so callers never check whether splits render.
 
 Removing a pane clears its remembered id; a later side open creates a new pane. The last visible
 ordinary pane stays when its final tab closes and shows the New launcher. An empty workspace does

docs/floating-panels.md

@@ -198,6 +198,40 @@ viewport keeps the last keyboard reservation until the next opening replaces
 it, so a capped draft keeps one height through every keyboard transition
 instead of expanding on close and shrinking again on open.
 
+Fullscreen is a layout mode of the dock, not a second editor. `ComposerDock
+fullscreen` fills the stationary viewport with the composer slot over the
+still-mounted content, paints its own surface under the safe areas, and turns
+the surface translation off. The composer's single tree keeps the editing
+surface at the same position in both modes, so the mounted editor, its native
+buffer, selection, and focus survive the toggle and Send's clear always reaches
+the live input. The one remount left is a viewport crossing the compact
+breakpoint: the app shell swaps its gesture wrapper and the workspace screen
+mounts tabs in different trees, so every screen below remounts. The draft owner
+restores the text and the editing session restores the caret and focus intent.
+New workspace keys its sessions by draft in the app-level store for the same
+reason. The centered form honors fullscreen by style alone: no centering, no
+translation, setup fields hidden, slot filling the stationary viewport. The
+global exit action (Escape, hardware back) is registered only for the active
+composer: a retained tab keeps its fullscreen editor mounted while hidden, the
+sheet suspends pane focus, and the composer gives up input from the moment the
+user asks for the compact agent list or explorer, before the panel's motion
+settles. Pane focus itself stays put under those panels: the agent panel reads
+it as "the user is in this chat" for attention clearing, and opening the agent
+list must not clear the attention it shows.
+The band beside the inline editor where the fullscreen glyph sits is the input's
+own right padding, so a tap anywhere in it focuses the editor whether or not the
+glyph shows. On web the slot is a fixed box over the visible viewport, which is
+also what lets a zoomed mobile page pan under it. Inside the slot, `ComposerFullscreenBody` reserves the keyboard
+height as a bottom margin at move start and end (boundary-time, like the
+capacity reservation) while `ComposerFullscreenFooter` rides the keyboard per
+frame with `KeyboardTranslateView`, so Send lands on the keyboard without a gap
+and without animating the editor's height. The screen that owns the chrome
+unmounts it: the workspace screen reads `useComposerTabFullscreen` for the
+active tab and New workspace reads the mounted composer's session. Hosts that
+render the dock pass the same `ComposerEditingSession` to the `Composer` so the
+dock, chrome, and editor agree on one fullscreen state. Escape (web overlay
+registration, focus untouched) and the Android back button leave fullscreen.
+
 Keep setup fields out of the composer's shrink chain. New workspace supplies its
 setup fields as the first dock child so they move up under the header as the draft
 grows. Putting the fields and composer in one bounded, shrinkable column made
@@ -304,7 +338,9 @@ track phase.
 
 All sheets use the app-wide Gorhom modal provider through `IsolatedBottomSheetModal`. This
 includes native centered dialogs: separate React Native Modals cannot present a root-owned
-sibling dialog over an existing iOS presenter.
+sibling dialog over an existing iOS presenter. The one exception is the
+[workspace sheet](explorer-sidebar.md#workspace-sheet), an in-tree Gorhom `BottomSheet` that hosts a
+whole workspace panel.
 
 The wrapper must give Gorhom an object ref. Gorhom accepts a callback ref at the React boundary
 but stores it in the modal queue and later reads `.current`; provider dismissal, replacement,

docs/glossary.md

@@ -21,6 +21,7 @@ Authoritative terminology. UI label wins. Don't invent synonyms; use what's here
 - **Repository / Remote** — Internal Git observations. They may produce mutable kind, branch, and project-grouping metadata but never the host-local project ID, root, display name, or workspace membership. No UI label.
 - **Sidebar items** — The configurable entries of the app sidebar, in two sections. Header: the rows at the head of the sidebar — New workspace, History, Search, Schedules, and plugin header items. Footer: the full-width rows between Add project and the footer icon row — Usage and plugin footer items. Add project and the icon row (Hosts, Help and support, Settings) are fixed and are not sidebar items. A plugin item may render several rows, such as one per bot; it is still one item that moves and hides as a block. Each section's order and visibility is one per-device preference (`AppSettings.sidebarNavItems`, `AppSettings.sidebarFooterItems`); every item may be off. UI: the Header and Footer cards on the Sidebar settings page. Code: `packages/app/src/sidebar-nav/model.ts` resolves a section, and the sidebar (`components/sidebar/sidebar-nav-rows.tsx`, the footer in `components/left-sidebar.tsx`) and the settings page (`screens/settings/sidebar/sidebar-nav-section.tsx`) read it through `useSidebarNavItems(section)`. Never hardcode one of these entries or add a second place that decides which ones show. Don't confuse with **Explorer sidebar**.
 - **Explorer sidebar** — The dedicated navigation dock containing the Files and Changes trees. UI: "Explorer sidebar". Code: `packages/app/src/workspace-tabs/explorer-sidebar.ts`; persisted pane identifiers retain the `explorer` spelling. See [explorer-sidebar.md](explorer-sidebar.md).
+- **Workspace sheet** — A compact sheet that holds one file or subagent tab over the workspace without adding it to the tab switcher; opening another target from a sheet stacks a new one on top. UI action: "Open as tab". Code: `sheetsByWorkspace` in `packages/app/src/stores/workspace-layout-store.ts`, `WorkspaceSheetHost` (`packages/app/src/screens/workspace/workspace-sheet-host.tsx`). See [explorer-sidebar.md](explorer-sidebar.md#workspace-sheet).
 - **Side pane** — An ordinary right-side workspace pane used for content opened beside the user's work. It closes and participates in workspace splits like every other main-host pane. See [explorer-sidebar.md](explorer-sidebar.md#side-pane). Forbidden: "Side panel".
 - **Directory-backed surface** — A right-sidebar surface whose content is determined by the workspace's `cwd`, so two workspaces on the same directory see identical content: git diff/status, forge change-request info, file preview/explorer contents. Keyed by `(serverId, cwd)`, never `workspaceId`. See [architecture.md](architecture.md#right-sidebar-boundary-directory-backed-vs-workspace-owned).
 - **Workspace-owned state** — Per-workspace state that never leaks to a same-`cwd` sibling: tabs, agents, terminals, panes, title, plus review drafts, diff-mode overrides, composer attachments, and file-explorer open/expand state. Keyed by `workspaceId` (`cwd` only as a fallback for old payloads). See [architecture.md](architecture.md#right-sidebar-boundary-directory-backed-vs-workspace-owned).

nix/desktop-package.nix

@@ -86,6 +86,12 @@ buildNpmPackage {
     # Expo's web build pulls in some pre-bundled assets; ensure it doesn't try
     # to phone home during the build.
     CI = "1";
+    # Metro's worker runs out of heap transforming the generated
+    # ws-outbound.aot.js validator (about 12 MB). Node's default heap limit is
+    # 2 GB on machines with less than 15 GB of memory, such as GitHub's 7 GB
+    # macOS runners, and 4 GB above that. 4096 MB is that 4 GB ceiling, so this
+    # only raises the limit on smaller builders, like desktop-release.yml does.
+    NODE_OPTIONS = "--max-old-space-size=4096";
   };
 
   buildPhase = ''

packages/app/e2e/browser/add-project-flow.spec.ts

@@ -223,6 +223,7 @@ test.describe("Add Project command-center flow", () => {
 
     await page.keyboard.press("Enter");
     await expectAddProjectPage(page, "directory-search");
+    await expect(addProjectFlowInput(page)).toBeFocused();
     await page.keyboard.type(projectPickerFixture.fuzzyQuery);
     await expect(addProjectFlow(page)).toContainText(projectPickerFixture.projectName, {
       timeout: 30_000,

packages/app/e2e/browser/appearance-font-family.spec.ts

@@ -0,0 +1,48 @@
+import { expect, test } from "../support/fixtures";
+import type { Page } from "@playwright/test";
+import { openSettingsSection } from "../support/helpers/settings";
+
+async function openAppearance(page: Page) {
+  await page.goto("/settings");
+  await openSettingsSection(page, "appearance");
+}
+
+async function setFontFamily(page: Page, name: string, family: string) {
+  const input = page.getByRole("textbox", { name });
+  await input.fill(family);
+  await input.press("Tab");
+}
+
+for (const name of ["Code font family", "Interface font family"]) {
+  test(`keeps settings usable after an unfinished quote in ${name}`, async ({ page }, testInfo) => {
+    await openAppearance(page);
+    await setFontFamily(page, name, "'Fira Code', monospace");
+    await expect(page.getByRole("textbox", { name })).toHaveValue("'Fira Code', monospace");
+
+    await setFontFamily(page, name, "'foo");
+    await expect(page.getByRole("textbox", { name })).toHaveValue("'Fira Code', monospace");
+    await expect(page.getByRole("button", { name: "Appearance", exact: true })).toBeInViewport();
+    await expect(page.getByText("Theme", { exact: true }).first()).toHaveCSS("font-size", "12px");
+
+    await page.screenshot({ path: testInfo.outputPath("rejected-font.png") });
+    await page.reload();
+    await expect(page.getByRole("textbox", { name })).toHaveValue("'Fira Code', monospace");
+    await expect(page.getByRole("button", { name: "Appearance", exact: true })).toBeInViewport();
+    await setFontFamily(page, name, "");
+    await expect(page.getByRole("textbox", { name })).toHaveValue("");
+  });
+}
+
+test("opens settings with defaults when a malformed font was already saved", async ({ page }) => {
+  await page.addInitScript(() => {
+    localStorage.setItem(
+      "@paseo:app-settings",
+      JSON.stringify({ monoFontFamily: "'foo", uiFontFamily: '"foo' }),
+    );
+  });
+  await openAppearance(page);
+  await expect(page.getByRole("textbox", { name: "Code font family" })).toHaveValue("");
+  await expect(page.getByRole("textbox", { name: "Interface font family" })).toHaveValue("");
+  await expect(page.getByRole("button", { name: "Appearance", exact: true })).toBeInViewport();
+  await expect(page.getByText("Theme", { exact: true }).first()).toHaveCSS("font-size", "12px");
+});

packages/app/e2e/browser/appearance-size-race.diagnostic.spec.ts

@@ -0,0 +1,70 @@
+import { expect, test } from "../support/fixtures";
+import type { Page } from "@playwright/test";
+import { openSettingsSection } from "../support/helpers/settings";
+
+async function openDefaultAppearance(page: Page) {
+  await page.addInitScript(() => {
+    localStorage.setItem("@paseo:app-settings", JSON.stringify({ codeFontSize: 12 }));
+    const observations: unknown[] = [];
+    Object.assign(window, { fontRaceObservations: observations });
+    for (const type of ["input", "change", "keydown", "focusin", "focusout"]) {
+      document.addEventListener(
+        type,
+        (event) => {
+          const input = event.target as HTMLInputElement;
+          if (!input?.getAttribute?.("aria-label")?.startsWith("Code font")) return;
+          observations.push({
+            type,
+            label: input.getAttribute("aria-label"),
+            value: input.value,
+            key: (event as KeyboardEvent).key,
+            at: performance.now(),
+          });
+        },
+        true,
+      );
+    }
+    new MutationObserver((records) => {
+      for (const record of records)
+        for (const removed of record.removedNodes) {
+          if (
+            removed instanceof Element &&
+            (removed.matches('[aria-label="Code font size"]') ||
+              removed.querySelector('[aria-label="Code font size"]'))
+          )
+            observations.push({ type: "removed-size-input", at: performance.now() });
+        }
+    }).observe(document, { childList: true, subtree: true });
+  });
+  await page.goto("/settings");
+  await openSettingsSection(page, "appearance");
+}
+
+async function changeCodeFamilyThenSize(page: Page) {
+  await page.getByLabel("Code font family").fill("Courier New, Courier, monospace");
+  await page.getByLabel("Code font family").press("Enter");
+  await page.getByLabel("Code font size").fill("18");
+  await page.getByLabel("Code font size").press("Enter");
+}
+
+test("keeps the size entered immediately after changing the code font family", async ({
+  page,
+}, testInfo) => {
+  await openDefaultAppearance(page);
+  try {
+    await changeCodeFamilyThenSize(page);
+    await expect(page.getByLabel("Code font size")).toHaveValue("18");
+  } finally {
+    await testInfo.attach("font-race", {
+      body: JSON.stringify(
+        await page.evaluate(() => ({
+          events: (window as Window & { fontRaceObservations: unknown[] }).fontRaceObservations,
+          stored: localStorage.getItem("@paseo:app-settings"),
+        })),
+        null,
+        2,
+      ),
+      contentType: "application/json",
+    });
+  }
+});

packages/app/e2e/browser/compact-workspace-sheet.spec.ts

@@ -0,0 +1,106 @@
+import { readFile, writeFile } from "node:fs/promises";
+import path from "node:path";
+import { expect, test } from "../support/fixtures";
+import { expectComposerVisible } from "../support/helpers/composer";
+import { installDaemonWebSocketGate } from "../support/helpers/daemon-websocket-gate";
+import { openAgentRoute, seedMockAgentWorkspace } from "../support/helpers/mock-agent";
+import { openSubagentFromCompactTrack, seedSubagent } from "../support/helpers/subagents";
+import {
+  closeWorkspaceSheet,
+  expectOpenTabCount,
+  openWorkspaceSheetAsTab,
+  expectDeclinedDiscardPrompt,
+  expectWorkspaceSheetAtSnap,
+  replaceWorkspaceSheetFileText,
+  selectTabFromSwitcher,
+  tapWorkspaceSheetBackdrop,
+  workspaceSheet,
+} from "../support/helpers/workspace-sheet";
+
+const FILE_LINK = "linked.ts:3";
+
+function promptMentioning(target: string): string {
+  return [
+    "Generate a title and a git branch name for a coding agent from the user prompt and attachments.",
+    "Return JSON only with fields 'title' and 'branch'.",
+    "",
+    "<user-prompt>",
+    `Open \`${target}\` now`,
+    "</user-prompt>",
+  ].join("\n");
+}
+
+test("compact opens files and subagents in a sheet, leaving the tabs for agents", async ({
+  page,
+}) => {
+  await page.setViewportSize({ width: 390, height: 844 });
+  const workspace = await seedMockAgentWorkspace({
+    repoPrefix: "compact-workspace-sheet-",
+    title: "Sheet parent",
+    initialPrompt: promptMentioning(FILE_LINK),
+  });
+  try {
+    const gate = await installDaemonWebSocketGate(page);
+    const linkedPath = path.join(workspace.cwd, "linked.ts");
+    await writeFile(linkedPath, "one\ntwo\nthree\n", "utf8");
+    const child = await seedSubagent(
+      { client: workspace.client, repoPath: workspace.cwd, workspaceId: workspace.workspaceId },
+      { parentId: workspace.agentId, title: "Sheet child" },
+    );
+    await openAgentRoute(page, { workspaceId: workspace.workspaceId, agentId: workspace.agentId });
+    await expectOpenTabCount(page, 1);
+
+    await test.step("a chat file link opens the file in a sheet", async () => {
+      const fileLink = page.getByText(FILE_LINK, { exact: true });
+      await expect(fileLink).toBeVisible({ timeout: 15_000 });
+      await fileLink.click();
+
+      const sheet = workspaceSheet(page, "linked.ts");
+      await expect(sheet).toBeVisible();
+      await expect(sheet.getByText("three")).toBeVisible();
+      await expectWorkspaceSheetAtSnap(page, "linked.ts");
+      await expect(sheet.getByRole("button", { name: "Open as tab" })).toHaveCount(0);
+      await expectOpenTabCount(page, 1);
+      await closeWorkspaceSheet(page, "linked.ts");
+    });
+
+    await test.step("a subagent opens in a sheet without its composer", async () => {
+      await openSubagentFromCompactTrack(page, child.id);
+
+      const sheet = workspaceSheet(page, child.title);
+      await expect(sheet).toBeVisible();
+      await expectWorkspaceSheetAtSnap(page, child.title);
+      await expect(sheet.getByRole("textbox", { name: "Message agent..." })).toHaveCount(0);
+      await expectOpenTabCount(page, 1);
+    });
+
+    await test.step("Open as tab promotes the subagent to a full tab", async () => {
+      await openWorkspaceSheetAsTab(page, child.title);
+      await expectOpenTabCount(page, 2);
+      await expectComposerVisible(page);
+    });
+
+    await test.step("a sheet with unsaved edits closes only through the guarded close", async () => {
+      await selectTabFromSwitcher(page, "Sheet parent");
+      await page.getByText(FILE_LINK, { exact: true }).click();
+      const sheet = workspaceSheet(page, "linked.ts");
+      await expect(sheet).toBeVisible();
+      // Hold the autosave so the edit stays unsaved.
+      gate.holdNextClientRequest("fs.file.write.request");
+      await replaceWorkspaceSheetFileText(page, "linked.ts", "edited in the sheet");
+      await gate.waitForHeldClientRequest();
+
+      await expectDeclinedDiscardPrompt(page, () => tapWorkspaceSheetBackdrop(page));
+      await expect(sheet.locator(".cm-content")).toHaveText("edited in the sheet");
+      await expectDeclinedDiscardPrompt(page, () =>
+        sheet.getByRole("button", { name: "Close" }).click(),
+      );
+      await expect(sheet.locator(".cm-content")).toHaveText("edited in the sheet");
+
+      gate.releaseHeldClientRequest();
+      await expect.poll(() => readFile(linkedPath, "utf8")).toBe("edited in the sheet");
+    });
+  } finally {
+    await workspace.cleanup();
+  }
+});

packages/app/e2e/browser/composer-autocomplete.spec.ts

@@ -9,7 +9,12 @@ import { expectWorkspaceTabVisible, openSessions } from "../support/helpers/arch
 import { daemonWsRoutePattern } from "../support/helpers/daemon-port";
 import { getServerId } from "../support/helpers/server-id";
 import { switchWorkspaceViaSidebar } from "../support/helpers/workspace-ui";
-import { expectMobileAgentSidebarVisible } from "../support/helpers/sidebar";
+import {
+  closeMobileAgentSidebar,
+  expectMobileAgentSidebarHidden,
+  expectMobileAgentSidebarVisible,
+  openMobileAgentSidebar,
+} from "../support/helpers/sidebar";
 import { expectNewWorkspaceProjectSelected } from "../support/helpers/new-workspace";
 
 const TEST_COMMANDS = [
@@ -96,16 +101,6 @@ interface PopoverFrameRecorderWindow extends Window {
   __stopComposerAutocompleteFrameRecorder?: () => void;
 }
 
-async function getTopTestIdAtPoint(page: Page, x: number, y: number) {
-  return page.evaluate(
-    ([pointX, pointY]) => {
-      const element = document.elementFromPoint(pointX, pointY);
-      return element?.closest("[data-testid]")?.getAttribute("data-testid") ?? null;
-    },
-    [x, y],
-  );
-}
-
 async function installListCommandsStub(page: Page): Promise<void> {
   await page.routeWebSocket(daemonWsRoutePattern(), (ws) => {
     const server = ws.connectToServer();
@@ -701,19 +696,15 @@ test.describe("Composer autocomplete", () => {
           timeout: 30_000,
         });
 
-        await page.getByRole("button", { name: "Open menu" }).click();
+        // The sidebar covers the composer, so the composer gives up its popover while the
+        // sidebar is open and brings it back once the sidebar closes.
+        await openMobileAgentSidebar(page);
         await expectMobileAgentSidebarVisible(page);
+        await expect(popover).toHaveCount(0);
 
-        const popoverBox = await popover.boundingBox();
-        expect(popoverBox).not.toBeNull();
-
-        const topTestId = await getTopTestIdAtPoint(
-          page,
-          popoverBox!.x + popoverBox!.width / 2,
-          popoverBox!.y + popoverBox!.height / 2,
-        );
-
-        expect(topTestId).not.toBe("composer-autocomplete-popover");
+        await closeMobileAgentSidebar(page);
+        await expectMobileAgentSidebarHidden(page);
+        await expect(popover.getByText("/help", { exact: true }).first()).toBeVisible();
       } finally {
         await agent.cleanup();
       }

packages/app/e2e/browser/composer-whitespace.spec.ts

@@ -20,6 +20,9 @@ import {
   queueComposerWithButton,
   configureComposerQueueSend,
   activateRetainedComposerTab,
+  switchComposerTabWithKeyboard,
+  expectWorkspaceHeaderHidden,
+  expectWorkspaceHeaderVisible,
   recordVisibleComposerGeometry,
   expectNoCollapsedVisibleComposer,
   expectAttachmentPill,
@@ -27,8 +30,14 @@ import {
   startRunningMockAgent,
   composerLocator,
   expectComposerVisible,
+  expectComposerFullscreenFitsVisibleViewport,
 } from "../support/helpers/composer";
 import { openAgentRoute, seedMockAgentWorkspace } from "../support/helpers/mock-agent";
+import {
+  closeMobileAgentSidebar,
+  expectMobileAgentSidebarHidden,
+  expectMobileAgentSidebarVisible,
+} from "../support/helpers/sidebar";
 
 async function composerHeight(page: Page): Promise<number> {
   return composerLocator(page).evaluate((element) => element.getBoundingClientRect().height);
@@ -156,6 +165,36 @@ test("composer growth keeps a bottom-pinned chat at the bottom", async ({ page }
   }
 });
 
+async function swipeOpenMobileAgentSidebar(page: Page): Promise<void> {
+  const viewport = page.viewportSize();
+  if (!viewport) throw new Error("viewport size is required");
+  const y = Math.round(viewport.height / 2);
+  await page.mouse.move(8, y);
+  await page.mouse.down();
+  await page.mouse.move(40, y, { steps: 4 });
+  await page.mouse.move(Math.round(viewport.width * 0.7), y, { steps: 12 });
+  await page.mouse.up();
+}
+
+/** Freeze the page's timers and animation frames until `page.clock.resume()`. */
+async function pausePageClock(page: Page): Promise<void> {
+  const now = Date.now();
+  await page.clock.install({ time: now });
+  await page.clock.pauseAt(now);
+}
+
+/** The send error shares the footer with Send, so whatever keeps Send visible keeps it visible. */
+async function expectFullscreenErrorAboveSend(page: Page): Promise<void> {
+  const frame = page.getByTestId("composer-fullscreen");
+  const alertBox = (await frame.getByRole("alert").boundingBox())!;
+  const sendBox = (await page
+    .getByRole("button", { name: "Send message", exact: true })
+    .boundingBox())!;
+  const editorBox = (await composerLocator(page).boundingBox())!;
+  expect(alertBox.y).toBeGreaterThanOrEqual(editorBox.y + editorBox.height);
+  expect(alertBox.y + alertBox.height).toBeLessThanOrEqual(sendBox.y);
+}
+
 async function writeCompactDraft(page: Page, text: string): Promise<void> {
   await composerLocator(page).fill(text);
   await expect(composerLocator(page)).toHaveValue(text);
@@ -188,47 +227,107 @@ test("compact fullscreen editing preserves the live draft and selection and stay
     await resizeComposerViewport(page, "portrait");
     await openAgentRoute(page, agent);
     await expectComposerVisible(page);
-    await attachComposerTestImage(page);
-    await expectAttachmentPill(page, "composer-image-attachment-pill");
-    await writeCompactDraft(page, "First line\nSecond line");
-    await expect(page.getByRole("button", { name: "Fullscreen", exact: true })).toHaveCount(0);
-    await writeCompactDraft(page, "First line\nSecond line\nThird line");
-    await expect(page.getByRole("button", { name: "Fullscreen", exact: true })).toBeVisible();
-    await writeCompactDraft(
-      page,
-      "A sentence with enough words to wrap across several rendered lines in a narrow input. ".repeat(
-        4,
-      ),
-    );
-    await expect(page.getByRole("button", { name: "Fullscreen", exact: true })).toBeVisible();
-    await selectComposerDraftRange(page, 4, 17);
-    await enterComposerFullscreen(page);
-    await expectComposerFullscreenControls(page);
-    await expectComposerDraftSelection(page, 4, 17);
-    await expect(page.getByTestId("composer-image-attachment-pill")).toHaveCount(0);
-    await writeCompactDraft(page, "Edited fullscreen draft\nSecond line\nThird line");
-    await selectComposerDraftRange(page, 3, 12);
-    await exitComposerFullscreen(page);
-    await expect(composerLocator(page)).toHaveValue(
-      "Edited fullscreen draft\nSecond line\nThird line",
-    );
-    await expectComposerDraftSelection(page, 3, 12);
-    await expectAttachmentPill(page, "composer-image-attachment-pill");
-    await expect(composerLocator(page)).toBeFocused();
-    await enterComposerFullscreen(page);
-    await writeCompactDraft(page, "Short draft");
-    await expectComposerFullscreenControls(page);
-    await selectComposerDraftRange(page, 0, 5);
-    await resizeComposerViewport(page, "landscape");
-    await expectComposerFullscreenControls(page);
-    await expectComposerDraftSelection(page, 0, 5);
-    await expect(composerLocator(page)).toHaveValue("Short draft");
-    await expect(composerLocator(page)).toBeFocused();
+    await test.step("the affordance appears after two rendered lines, including soft wraps", async () => {
+      await attachComposerTestImage(page);
+      await expectAttachmentPill(page, "composer-image-attachment-pill");
+      await writeCompactDraft(page, "First line\nSecond line");
+      await expect(page.getByRole("button", { name: "Fullscreen", exact: true })).toHaveCount(0);
+      await writeCompactDraft(page, "First line\nSecond line\nThird line");
+      await expect(page.getByRole("button", { name: "Fullscreen", exact: true })).toBeVisible();
+      await writeCompactDraft(
+        page,
+        "A sentence with enough words to wrap across several rendered lines in a narrow input. ".repeat(
+          4,
+        ),
+      );
+      await expect(page.getByRole("button", { name: "Fullscreen", exact: true })).toBeVisible();
+    });
+    await test.step("fullscreen covers the header and keeps the live draft and selection", async () => {
+      await selectComposerDraftRange(page, 4, 17);
+      await enterComposerFullscreen(page);
+      await expectComposerFullscreenControls(page);
+      await expectWorkspaceHeaderHidden(page);
+      await expectComposerDraftSelection(page, 4, 17);
+      await expect(page.getByTestId("composer-image-attachment-pill")).toHaveCount(0);
+      await writeCompactDraft(page, "Edited fullscreen draft\nSecond line\nThird line");
+      await selectComposerDraftRange(page, 3, 12);
+    });
+    await test.step("exit restores the inline composer with the fullscreen edits", async () => {
+      await exitComposerFullscreen(page);
+      await expectWorkspaceHeaderVisible(page);
+      await expect(composerLocator(page)).toHaveValue(
+        "Edited fullscreen draft\nSecond line\nThird line",
+      );
+      await expectComposerDraftSelection(page, 3, 12);
+      await expectAttachmentPill(page, "composer-image-attachment-pill");
+      await expect(composerLocator(page)).toBeFocused();
+    });
+    await test.step("sending inline after a fullscreen edit clears the visible editor", async () => {
+      await sendComposerWithButton(page);
+      await expect(composerLocator(page)).toHaveValue("");
+      await expect(page.getByTestId("composer-image-attachment-pill")).toHaveCount(0);
+      await writeCompactDraft(page, "Typed after the fullscreen cycle");
+      await sendComposerWithButton(page);
+      await expect(composerLocator(page)).toHaveValue("");
+    });
+    await test.step("sending inside fullscreen clears the editor and keeps fullscreen open", async () => {
+      await writeCompactDraft(page, "First line\nSecond line\nThird line");
+      await enterComposerFullscreen(page);
+      await writeCompactDraft(page, "Short draft");
+      await expectComposerFullscreenControls(page);
+      await selectComposerDraftRange(page, 0, 5);
+      await resizeComposerViewport(page, "landscape");
+      await expectComposerFullscreenControls(page);
+      await expectComposerDraftSelection(page, 0, 5);
+      await expect(composerLocator(page)).toHaveValue("Short draft");
+      await expect(composerLocator(page)).toBeFocused();
+      await resizeComposerViewport(page, "portrait");
+      await sendComposerWithButton(page);
+      await expect(composerLocator(page)).toHaveValue("");
+      await expectComposerFullscreenControls(page);
+      await expect(page.getByRole("button", { name: "Send message", exact: true })).toBeDisabled();
+    });
+    await test.step("typing and sending keep working after leaving fullscreen again", async () => {
+      await writeCompactDraft(page, "Typed inside fullscreen");
+      await expect(page.getByRole("button", { name: "Send message", exact: true })).toBeEnabled();
+      await exitComposerFullscreen(page);
+      await expectWorkspaceHeaderVisible(page);
+      await expect(composerLocator(page)).toHaveValue("Typed inside fullscreen");
+      await writeCompactDraft(page, "Typed inside fullscreen, finished inline");
+      await sendComposerWithButton(page);
+      await expect(composerLocator(page)).toHaveValue("");
+      await writeCompactDraft(page, "One more inline message");
+      await sendComposerWithButton(page);
+      await expect(composerLocator(page)).toHaveValue("");
+    });
+  } finally {
+    await agent.cleanup();
+  }
+});
+
+test("a caret inside an unpublished edit survives a breakpoint remount", async ({ page }) => {
+  const agent = await seedMockAgentWorkspace({
+    repoPrefix: "composer-remount-caret-",
+    title: "Remount caret",
+  });
+  try {
     await resizeComposerViewport(page, "portrait");
-    await sendComposerWithButton(page);
-    await expect(composerLocator(page)).toHaveValue("");
-    await expectComposerFullscreenControls(page);
-    await expect(page.getByRole("button", { name: "Send message", exact: true })).toBeDisabled();
+    await openAgentRoute(page, agent);
+    await expectComposerVisible(page);
+    await writeCompactDraft(page, "Short draft");
+    await selectComposerDraftRange(page, 5, 5);
+    // The draft owner publishes web edits after the next paint. A rotation inside that
+    // window remounts the editor before the edit has reached the draft store; the paused
+    // clock holds the page there instead of racing the frame.
+    await pausePageClock(page);
+    await composerLocator(page).press("X");
+    await resizeComposerViewport(page, "landscape");
+    await page.clock.resume();
+    await expect(composerLocator(page)).toHaveValue("ShortX draft");
+    await expectComposerDraftSelection(page, 6, 6);
+    await expect(composerLocator(page)).toBeFocused();
+    await composerLocator(page).press("Y");
+    await expect(composerLocator(page)).toHaveValue("ShortXY draft");
   } finally {
     await agent.cleanup();
   }
@@ -253,6 +352,7 @@ test("fullscreen submit rejection retains the editable draft and supports retry"
     await expect(page.getByTestId("composer-fullscreen").getByRole("alert")).toHaveText(
       "Requested mock prompt rejection",
     );
+    await expectFullscreenErrorAboveSend(page);
     await expect(composerLocator(page)).toHaveValue(draft);
     await expect(composerLocator(page)).toBeEditable();
     await expect(page.getByRole("button", { name: "Send message", exact: true })).toBeEnabled();
@@ -264,6 +364,76 @@ test("fullscreen submit rejection retains the editable draft and supports retry"
   }
 });
 
+async function blurComposer(page: Page): Promise<void> {
+  await composerLocator(page).blur();
+  await expect(composerLocator(page)).not.toBeFocused();
+}
+
+/** Mid-band at the given height and near the editor's bottom edge. */
+async function reservedBandPoints(
+  page: Page,
+  bandX: number,
+  topY: number,
+): Promise<Array<{ x: number; y: number }>> {
+  const editor = (await composerLocator(page).boundingBox())!;
+  return [
+    { x: bandX, y: topY },
+    { x: bandX, y: editor.y + editor.height - 6 },
+  ];
+}
+
+test("the reserved band beside the inline editor focuses it", async ({ page }) => {
+  const agent = await seedMockAgentWorkspace({
+    repoPrefix: "composer-band-focus-",
+    title: "Composer band focus",
+  });
+  try {
+    await resizeComposerViewport(page, "portrait");
+    await openAgentRoute(page, agent);
+    await expectComposerVisible(page);
+    const exitButton = page.getByRole("button", { name: "Exit fullscreen", exact: true });
+    const fullscreenButton = page.getByRole("button", { name: "Fullscreen", exact: true });
+    const longDraft = "Band first line\nBand second line\nBand third line";
+    await writeCompactDraft(page, longDraft);
+    await expect(fullscreenButton).toBeVisible();
+    const button = (await fullscreenButton.boundingBox())!;
+    const bandX = button.x + button.width / 2;
+
+    await test.step("with the fullscreen button shown, the band under it focuses the editor", async () => {
+      for (const point of await reservedBandPoints(page, bandX, button.y + button.height + 10)) {
+        await blurComposer(page);
+        await page.mouse.click(point.x, point.y);
+        await expect(composerLocator(page)).toBeFocused();
+        await expect(composerLocator(page)).toHaveValue(longDraft);
+        await expect(exitButton).toHaveCount(0);
+      }
+    });
+
+    await test.step("the button itself still toggles fullscreen", async () => {
+      await fullscreenButton.click();
+      await expectComposerFullscreenControls(page);
+      await exitComposerFullscreen(page);
+      await expect(exitButton).toHaveCount(0);
+      await expect(composerLocator(page)).toHaveValue(longDraft);
+    });
+
+    await test.step("with no fullscreen button, the whole band still focuses the editor", async () => {
+      await writeCompactDraft(page, "Short");
+      await expect(fullscreenButton).toHaveCount(0);
+      const editor = (await composerLocator(page).boundingBox())!;
+      for (const point of await reservedBandPoints(page, bandX, editor.y + 6)) {
+        await blurComposer(page);
+        await page.mouse.click(point.x, point.y);
+        await expect(composerLocator(page)).toBeFocused();
+        await expect(composerLocator(page)).toHaveValue("Short");
+        await expect(exitButton).toHaveCount(0);
+      }
+    });
+  } finally {
+    await agent.cleanup();
+  }
+});
+
 test("fullscreen Send keeps the configured queue behavior while an agent runs", async ({
   page,
 }) => {
@@ -333,15 +503,28 @@ test("retained agent tabs preserve fullscreen editing and paste when switched aw
     const draft = "Live first line\nLive second line\nLive third line";
     await writeCompactDraft(page, draft);
     await enterComposerFullscreen(page);
+    await expectWorkspaceHeaderHidden(page);
     await selectComposerDraftRange(page, 4, 17);
-    await activateRetainedComposerTab(page, first.title);
+    // Fullscreen covers the compact header, so a phone leaves the tab by exiting first;
+    // a desktop-width window still has the tab shortcut.
+    await resizeComposerViewport(page, "landscape");
+    await switchComposerTabWithKeyboard(page, "previous");
     await expect(page.getByRole("button", { name: "Exit fullscreen", exact: true })).toHaveCount(0);
+    // The exit action belongs to the active pane: Escape here leaves the hidden tab alone.
+    await composerLocator(page).press("Escape");
+    await switchComposerTabWithKeyboard(page, "next");
+    await expectComposerFullscreenControls(page);
+    await switchComposerTabWithKeyboard(page, "previous");
+    await expect(page.getByRole("button", { name: "Exit fullscreen", exact: true })).toHaveCount(0);
+    await resizeComposerViewport(page, "portrait");
+    await expectWorkspaceHeaderVisible(page);
     await writeCompactDraft(page, "Other tab draft");
     await shrinkVisibleViewport(page);
     await activateRetainedComposerTab(page, second.title);
     await expectComposerFullscreenControls(page);
+    await expectWorkspaceHeaderHidden(page);
     await expect(composerLocator(page)).toHaveValue(draft);
-    await expectFullscreenInsideVisibleViewport(page);
+    await expectComposerFullscreenFitsVisibleViewport(page);
     await expectComposerDraftSelection(page, 4, 17);
     await expect(composerLocator(page)).toBeFocused();
     expect(await pasteComposerTestImage(page)).toBe(true);
@@ -352,6 +535,36 @@ test("retained agent tabs preserve fullscreen editing and paste when switched aw
   }
 });
 
+test("the compact sidebar over a fullscreen editor leaves the exit action alone", async ({
+  page,
+}) => {
+  const agent = await seedMockAgentWorkspace({
+    repoPrefix: "composer-fullscreen-sidebar-",
+    title: "Fullscreen under sidebar",
+  });
+  try {
+    await resizeComposerViewport(page, "portrait");
+    await openAgentRoute(page, agent);
+    const draft = "Line one\nLine two\nLine three";
+    await writeCompactDraft(page, draft);
+    await enterComposerFullscreen(page);
+    await expectWorkspaceHeaderHidden(page);
+    // Fullscreen hides the header's menu button; the edge swipe still opens the list over it.
+    await swipeOpenMobileAgentSidebar(page);
+    await expectMobileAgentSidebarVisible(page);
+    // The list covers the pane, so the editor's exit action is not armed.
+    await page.keyboard.press("Escape");
+    await closeMobileAgentSidebar(page);
+    await expectMobileAgentSidebarHidden(page);
+    await expectComposerFullscreenControls(page);
+    await expect(composerLocator(page)).toHaveValue(draft);
+    await exitComposerFullscreen(page);
+    await expectWorkspaceHeaderVisible(page);
+  } finally {
+    await agent.cleanup();
+  }
+});
+
 test("retained inline composers keep usable capacity through hidden tab geometry", async ({
   page,
 }) => {
@@ -408,30 +621,6 @@ async function panVisibleViewport(page: Page): Promise<void> {
   await cdp.detach();
 }
 
-async function expectFullscreenInsideVisibleViewport(page: Page): Promise<void> {
-  await expect
-    .poll(() =>
-      page.getByTestId("composer-fullscreen").evaluate((element) => {
-        const viewport = window.visualViewport!;
-        const frame = element.getBoundingClientRect();
-        const send = element.querySelector('[aria-label="Send message"]')!.getBoundingClientRect();
-        return {
-          frameFits:
-            Math.abs(frame.top - viewport.offsetTop) < 1 &&
-            Math.abs(frame.left - viewport.offsetLeft) < 1 &&
-            Math.abs(frame.height - viewport.height) < 1 &&
-            Math.abs(frame.width - viewport.width) < 1,
-          sendFits:
-            send.top >= viewport.offsetTop &&
-            send.bottom <= viewport.offsetTop + viewport.height &&
-            send.left >= viewport.offsetLeft &&
-            send.right <= viewport.offsetLeft + viewport.width,
-        };
-      }),
-    )
-    .toEqual({ frameFits: true, sendFits: true });
-}
-
 test("fullscreen Send follows the visible viewport when it shrinks and pans", async ({ page }) => {
   const agent = await seedMockAgentWorkspace({
     repoPrefix: "composer-visible-viewport-",
@@ -443,11 +632,11 @@ test("fullscreen Send follows the visible viewport when it shrinks and pans", as
     await expectComposerVisible(page);
     await writeCompactDraft(page, "First line\nSecond line\nThird line");
     await enterComposerFullscreen(page);
-    await expectFullscreenInsideVisibleViewport(page);
+    await expectComposerFullscreenFitsVisibleViewport(page);
     await shrinkVisibleViewport(page);
-    await expectFullscreenInsideVisibleViewport(page);
+    await expectComposerFullscreenFitsVisibleViewport(page);
     await panVisibleViewport(page);
-    await expectFullscreenInsideVisibleViewport(page);
+    await expectComposerFullscreenFitsVisibleViewport(page);
   } finally {
     await agent.cleanup();
   }

packages/app/e2e/browser/creation-old-daemon.spec.ts

@@ -116,6 +116,7 @@ for (const version of ["0.2.5", "0.7.2", "0.8.0"]) {
       );
       expect(workspaces).toHaveLength(1);
       gate.release();
+      await gate.waitForCreated();
       await expect.poll(async () => (await client.fetchAgents()).entries.length).toBe(1);
       const first = (await client.fetchAgents()).entries[0]!.agent;
       await client.waitForFinish(first.id, 20_000);
@@ -128,6 +129,7 @@ for (const version of ["0.2.5", "0.7.2", "0.8.0"]) {
       const secondPrompt = "Create another agent: emit 1 coalesced agent stream updates";
       await fillComposerDraft(page, secondPrompt);
       await pressSubmitBeforeTheNextRender(page, "Send message");
+      await gate.waitForCreated();
       await expect.poll(async () => (await client.fetchAgents()).entries.length).toBe(2);
       const second = (await client.fetchAgents()).entries.find(
         ({ agent }) => agent.id !== first.id,
@@ -206,21 +208,40 @@ for (const version of ["0.2.5", "0.7.2", "0.8.0"]) {
 async function holdLegacyAgentCreation(page: Page, port: number) {
   const readers = await loadSessionMessageReaders();
   const arrived = Promise.withResolvers<void>();
+  let created = Promise.withResolvers<void>();
+  let createRequestId: string | undefined;
   let release = () => {};
   let holding = true;
   await page.routeWebSocket(new RegExp(`:${port}/ws`), (browser) => {
     const server = browser.connectToServer();
     browser.onMessage((frame) => {
-      if (holding && readers.client(frame)?.type === "create_agent_request") {
+      const message = readers.client(frame);
+      if (message?.type === "create_agent_request") createRequestId = message.requestId;
+      if (holding && message?.type === "create_agent_request") {
         holding = false;
         release = () => server.send(frame);
         arrived.resolve();
       } else server.send(frame);
     });
-    server.onMessage((frame) => browser.send(frame));
+    server.onMessage((frame) => {
+      const message = readers.server(frame);
+      if (
+        message?.type === "status" &&
+        message.payload.status === "agent_created" &&
+        message.payload.requestId === createRequestId
+      ) {
+        created.resolve();
+      }
+      browser.send(frame);
+    });
   });
   return {
     waitForRequest: () => arrived.promise,
+    async waitForCreated() {
+      // Agent-list membership includes initialization, before the initial prompt starts.
+      await created.promise;
+      created = Promise.withResolvers<void>();
+    },
     release() {
       const send = release;
       release = () => {};

packages/app/e2e/browser/custom-model-removal.spec.ts

@@ -0,0 +1,29 @@
+import { test } from "../support/fixtures";
+import {
+  addCustomModel,
+  expectCustomModelRetained,
+  openCustomModels,
+  removeCustomModel,
+} from "../support/helpers/custom-models";
+
+const longModelId = "custom-model-with-a-long-name-".repeat(6);
+const shortModelId = "custom-short";
+
+for (const width of [1200, 390]) {
+  test(`removes a long custom model at ${width}px without removing another model`, async ({
+    page,
+  }) => {
+    await page.setViewportSize({ width: 1200, height: 1000 });
+    await openCustomModels(page);
+    await addCustomModel(page, shortModelId);
+    await addCustomModel(page, longModelId);
+
+    await test.step("remove the long model at the target width", async () => {
+      await page.setViewportSize({ width, height: 1000 });
+      await removeCustomModel(page, longModelId);
+      await expectCustomModelRetained(page, shortModelId);
+    });
+
+    await removeCustomModel(page, shortModelId);
+  });
+}

packages/app/e2e/browser/file-explorer-context-actions.spec.ts

@@ -2,10 +2,10 @@ import { mkdir, readFile, rm, writeFile } from "node:fs/promises";
 import path from "node:path";
 import { expect, type Page } from "@playwright/test";
 import { test } from "../support/fixtures";
-import { openFileExplorer } from "../support/helpers/file-explorer";
+import { downloadFileFromExplorer, openFileExplorer } from "../support/helpers/file-explorer";
 import { openChangesPanel } from "../support/helpers/workspace-tabs";
 import { gotoWorkspace } from "../support/helpers/launcher";
-import { daemonWsRoutePattern } from "../support/helpers/daemon-port";
+import { daemonWsRoutePattern, getE2EDaemonPort } from "../support/helpers/daemon-port";
 import { seedWorkspace, type SeededWorkspace } from "../support/helpers/seed-client";
 
 let workspace: SeededWorkspace;
@@ -444,3 +444,25 @@ test("hides unsupported file operations and revert actions", async ({ page }) =>
   await expect(page.getByTestId("diff-file-0-duplicate")).toHaveCount(0);
   await expect(page.getByTestId("diff-file-0-revert")).toHaveCount(0);
 });
+
+test("downloads a file over direct TCP with its original filename and bytes", async ({
+  page,
+}, testInfo) => {
+  const fileName = "rapport données.bin";
+  const source = Buffer.from([0, 1, 2, 127, 128, 255, 10]);
+  await writeFile(path.join(workspace.workspaceDirectory, fileName), source);
+  await gotoWorkspace(page, workspace.workspaceId);
+  await openFileExplorer(page);
+
+  const downloaded = await downloadFileFromExplorer(page, fileName);
+  const url = new URL(downloaded.url());
+  expect(url.protocol).toBe("http:");
+  expect(url.port).toBe(getE2EDaemonPort());
+  expect(url.pathname).toBe("/api/files/download");
+  expect(url.searchParams.get("token")).toBeTruthy();
+  expect(downloaded.suggestedFilename()).toBe(fileName);
+  const savedFile = testInfo.outputPath(fileName);
+  await downloaded.saveAs(savedFile);
+  expect(await downloaded.failure()).toBeNull();
+  expect(await readFile(savedFile)).toEqual(source);
+});

packages/app/e2e/browser/new-workspace-launch-terminal.spec.ts

@@ -1,7 +1,18 @@
-import { expect, test } from "../support/fixtures";
+import { expect, test, type Page } from "../support/fixtures";
 import { gotoAppShell } from "../support/helpers/app";
 import { waitForSidebarHydration } from "../support/helpers/workspace-ui";
-import { openNewWorkspaceComposer } from "../support/helpers/new-workspace";
+import {
+  expectNewWorkspaceDraft,
+  fillNewWorkspaceDraft,
+  openNewWorkspaceComposer,
+} from "../support/helpers/new-workspace";
+import {
+  composerLocator,
+  enterComposerFullscreen,
+  exitComposerFullscreen,
+  expectComposerFullscreenControls,
+  resizeComposerViewport,
+} from "../support/helpers/composer";
 import { seedWorkspace, type SeededWorkspace } from "../support/helpers/seed-client";
 import {
   expectTerminalLaunchSelected,
@@ -145,3 +156,117 @@ test.describe("New workspace: launching a terminal", () => {
     });
   });
 });
+
+async function expectNewWorkspaceHeaderHidden(page: Page): Promise<void> {
+  await expect(page.getByTestId("menu-button").filter({ visible: true })).toHaveCount(0);
+}
+
+async function expectNewWorkspaceHeaderVisible(page: Page): Promise<void> {
+  await expect(page.getByTestId("menu-button").filter({ visible: true }).first()).toBeVisible();
+}
+
+/**
+ * Fullscreen fills the content area top to bottom and out to the right edge (a pinned
+ * sidebar keeps its column), covers the form, and shows only exit and the mode's submit.
+ */
+async function expectNewWorkspaceFullscreen(page: Page, submitLabel: string): Promise<void> {
+  const frame = page.getByTestId("composer-fullscreen");
+  await expect(page.getByRole("button", { name: "Exit fullscreen", exact: true })).toBeVisible();
+  await expect(frame.getByRole("button")).toHaveCount(2);
+  await expect(frame.getByRole("button", { name: submitLabel })).toBeVisible();
+  await expectNewWorkspaceHeaderHidden(page);
+  const picker = (await page.getByRole("button", { name: "Workspace project" }).boundingBox())!;
+  await expect
+    .poll(() =>
+      frame.evaluate(
+        (element, point) => {
+          const viewport = window.visualViewport!;
+          const box = element.getBoundingClientRect();
+          const covering = document.elementFromPoint(point.x, point.y);
+          return {
+            fillsHeight:
+              Math.abs(box.top - viewport.offsetTop) < 1 &&
+              Math.abs(box.height - viewport.height) < 1,
+            reachesRightEdge:
+              Math.abs(box.right - (viewport.offsetLeft + viewport.width)) < 1 &&
+              box.left >= viewport.offsetLeft,
+            coversForm: element.contains(covering),
+          };
+        },
+        { x: picker.x + picker.width / 2, y: picker.y + picker.height / 2 },
+      ),
+    )
+    .toEqual({ fillsHeight: true, reachesRightEdge: true, coversForm: true });
+}
+
+test.describe("New workspace: fullscreen composer across the compact breakpoint", () => {
+  let workspace: SeededWorkspace;
+
+  test.beforeEach(async () => {
+    workspace = await seedWorkspace({ repoPrefix: "launch-fullscreen-" });
+  });
+
+  test.afterEach(async () => {
+    await workspace?.cleanup();
+  });
+
+  test("chat fullscreen survives widening and terminal fullscreen fills the phone", async ({
+    page,
+  }) => {
+    test.setTimeout(90_000);
+    await gotoAppShell(page);
+    await waitForSidebarHydration(page);
+    await openNewWorkspaceComposer(page, {
+      projectKey: workspace.projectKey,
+      projectDisplayName: workspace.projectDisplayName,
+    });
+    const projectPicker = page.getByRole("button", { name: "Workspace project" });
+
+    await test.step("chat: fullscreen covers the centered form and exits back into it", async () => {
+      await resizeComposerViewport(page, "portrait");
+      const draft = "Chat first line\nChat second line\nChat third line";
+      await fillNewWorkspaceDraft(page, draft);
+      await enterComposerFullscreen(page);
+      await expectComposerFullscreenControls(page);
+      await expectNewWorkspaceHeaderHidden(page);
+      await resizeComposerViewport(page, "landscape");
+      await expectComposerFullscreenControls(page);
+      await expectNewWorkspaceFullscreen(page, "Create");
+      // The desktop form's own import button is dropped from the fullscreen slot.
+      await expect(
+        page.getByTestId("new-workspace-import-session").filter({ visible: true }),
+      ).toHaveCount(0);
+      await composerLocator(page).press("End");
+      await composerLocator(page).pressSequentially(" wide");
+      await exitComposerFullscreen(page);
+      await expectNewWorkspaceHeaderVisible(page);
+      await expect(projectPicker).toBeVisible();
+      await expect(
+        page.getByTestId("new-workspace-import-session").filter({ visible: true }),
+      ).toBeVisible();
+      await expectNewWorkspaceDraft(page, `${draft} wide`);
+    });
+
+    // Terminal mode and its prompt are screen state, and the shell remounts the screen
+    // at the breakpoint, so the terminal prompt's fullscreen is exercised on the phone
+    // layout only.
+    await test.step("terminal: the prompt's fullscreen shows only exit and Launch", async () => {
+      await resizeComposerViewport(page, "portrait");
+      // The compact launch control opens a sheet, not the desktop menu.
+      await launchTrigger(page).click();
+      const option = page.getByRole("menuitem").filter({ hasText: PROMPT_PROFILE.name });
+      await option.click();
+      await expect(option).not.toBeVisible();
+      await expectTerminalLaunchSelected(page, PROMPT_PROFILE.name);
+      const prompt = "Prompt first line\nPrompt second line\nPrompt third line";
+      await fillTerminalPrompt(page, prompt);
+      await enterComposerFullscreen(page);
+      await expect(terminalPromptInput(page)).toBeVisible();
+      await expectNewWorkspaceFullscreen(page, "Launch");
+      await exitComposerFullscreen(page);
+      await expectNewWorkspaceHeaderVisible(page);
+      await expect(projectPicker).toBeVisible();
+      await expect(terminalPromptInput(page)).toHaveValue(prompt);
+    });
+  });
+});

packages/app/e2e/browser/question-prompt-pagination.spec.ts

@@ -7,6 +7,7 @@ import {
   expectQuestionDismissEnabled,
   expectQuestionHidden,
   expectQuestionNavigationEnabled,
+  expectQuestionOptionPreview,
   expectQuestionOptionSelected,
   expectQuestionPrimaryActionDisabled,
   expectQuestionPrimaryActionEnabled,
@@ -61,6 +62,10 @@ test.describe("Question prompt pagination", () => {
       await expectQuestionOptionSelected(page, "App");
 
       await openQuestion(page, { index: 2, total: TOTAL_QUESTIONS });
+      await expectQuestionOptionPreview(page, {
+        option: "Behind feature flag",
+        preview: 'flags.enabled("new-surface")',
+      });
       await chooseQuestionOption(page, "Behind feature flag");
       await expectCurrentQuestion(page, {
         index: 3,

packages/app/e2e/browser/workspace-relative-navigation.spec.ts

@@ -0,0 +1,74 @@
+import type { Page } from "@playwright/test";
+import { test, expect } from "../support/fixtures";
+import { gotoAppShell } from "../support/helpers/app";
+import { seedWorkspace } from "../support/helpers/seed-client";
+import { getServerId } from "../support/helpers/server-id";
+import {
+  expectSidebarWorkspaceSelected,
+  switchWorkspaceViaSidebar,
+} from "../support/helpers/workspace-ui";
+
+async function readVisibleWorkspaceOrder(page: Page): Promise<string[]> {
+  const rows = page.getByRole("button", { name: /^Workspace \d{2}$/ });
+  await expect(rows).toHaveCount(12);
+  return rows.evaluateAll(
+    (elements, prefix) =>
+      elements.map((element) => element.getAttribute("data-testid")!.slice(prefix.length)),
+    `sidebar-workspace-row-${getServerId()}:`,
+  );
+}
+
+async function navigateWorkspace(
+  page: Page,
+  direction: "next" | "previous",
+  workspaceId: string,
+): Promise<void> {
+  await page.keyboard.press(direction === "next" ? "Alt+]" : "Alt+[");
+  await expectSidebarWorkspaceSelected({ page, serverId: getServerId(), workspaceId });
+  await expect(page).toHaveURL(new RegExp(`/workspace/${workspaceId}$`));
+}
+
+test("previous and next traverse every visible workspace while digit shortcuts stop at nine", async ({
+  page,
+}) => {
+  test.setTimeout(120_000);
+  const project = await seedWorkspace({
+    repoPrefix: "relative-navigation-",
+    title: "Workspace 01",
+  });
+  try {
+    for (let index = 2; index <= 12; index += 1) {
+      const created = await project.client.createWorkspace({
+        source: { kind: "directory", path: project.repoPath },
+        title: `Workspace ${String(index).padStart(2, "0")}`,
+      });
+      expect(created.error).toBeNull();
+    }
+    await page.setViewportSize({ width: 1440, height: 1100 });
+    await gotoAppShell(page);
+    const order = await readVisibleWorkspaceOrder(page);
+
+    await test.step("next crosses the ninth workspace and previous returns to it", async () => {
+      await switchWorkspaceViaSidebar({ page, serverId: getServerId(), workspaceId: order[8] });
+      await navigateWorkspace(page, "next", order[9]);
+      await navigateWorkspace(page, "previous", order[8]);
+    });
+
+    await test.step("wrapping uses the true first and last visible workspace", async () => {
+      await switchWorkspaceViaSidebar({ page, serverId: getServerId(), workspaceId: order[0] });
+      await navigateWorkspace(page, "previous", order[11]);
+      await navigateWorkspace(page, "next", order[0]);
+    });
+
+    await test.step("the ninth digit shortcut still selects the ninth workspace", async () => {
+      await page.keyboard.press("Alt+9");
+      await expectSidebarWorkspaceSelected({
+        page,
+        serverId: getServerId(),
+        workspaceId: order[8],
+      });
+    });
+  } finally {
+    await project.cleanup();
+  }
+});

packages/app/e2e/mobile/agent-device/native-question-option-preview-preconditions.md

@@ -0,0 +1,7 @@
+# Native question option preview
+
+`native-question-option-preview.android.ad` checks that every line of a long option preview is reachable on Android. Before replay, open a mock agent prompted with `emit synthetic questions` so its question card shows the first question, on a phone-sized emulator (validated on a 1080×1920 API 35 AVD). The flow opens the `rollout` question, drags slowly up from inside the "Behind feature flag" preview, and asserts the preview's last line is visible.
+
+```sh
+agent-device replay packages/app/e2e/mobile/agent-device/native-question-option-preview.android.ad --platform android --serial emulator-5554
+```

packages/app/e2e/mobile/agent-device/native-question-option-preview.android.ad

@@ -0,0 +1,10 @@
+context platform=android timeout=60000 retries=0
+env APP_ID=sh.paseo.debug
+
+open "${APP_ID}"
+wait "label=\"rollout\"" 20000
+press "label=\"rollout\""
+wait "id=\"question-form-option-preview\"" 10000
+gesture pan 570 1120 0 -440 600
+is visible "text=\"// LAST PREVIEW LINE\""
+close

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

@@ -355,6 +355,12 @@ export async function resizeComposerViewport(
     short: { width: 390, height: 390 },
   };
   await page.setViewportSize(sizes[orientation]);
+  // Before the app has loaded there is no layout to wait for.
+  if (page.url() === "about:blank") return;
+  // Crossing the compact breakpoint remounts the shell and the editor. Anything that
+  // follows (a shortcut, a locator) belongs to the layout the new size implies, so
+  // wait for that layout before returning.
+  await expect(page.getByTestId("compact-shell")).toHaveCount(orientation === "landscape" ? 0 : 1);
 }
 export async function selectComposerDraftRange(
   page: Page,
@@ -390,6 +396,33 @@ export async function expectComposerFullscreenControls(page: Page): Promise<void
   await expect(page.getByTestId("composer-fullscreen").getByRole("button")).toHaveCount(2);
   await expect(composerInput(page)).toHaveCount(1);
 }
+/** The fullscreen frame and its submit button sit inside the browser's visible viewport. */
+export async function expectComposerFullscreenFitsVisibleViewport(
+  page: Page,
+  submitLabel = "Send message",
+): Promise<void> {
+  await expect
+    .poll(() =>
+      page.getByTestId("composer-fullscreen").evaluate((element, label) => {
+        const viewport = window.visualViewport!;
+        const frame = element.getBoundingClientRect();
+        const send = element.querySelector(`[aria-label="${label}"]`)!.getBoundingClientRect();
+        return {
+          frameFits:
+            Math.abs(frame.top - viewport.offsetTop) < 1 &&
+            Math.abs(frame.left - viewport.offsetLeft) < 1 &&
+            Math.abs(frame.height - viewport.height) < 1 &&
+            Math.abs(frame.width - viewport.width) < 1,
+          sendFits:
+            send.top >= viewport.offsetTop &&
+            send.bottom <= viewport.offsetTop + viewport.height &&
+            send.left >= viewport.offsetLeft &&
+            send.right <= viewport.offsetLeft + viewport.width,
+        };
+      }, submitLabel),
+    )
+    .toEqual({ frameFits: true, sendFits: true });
+}
 export async function sendComposerWithButton(page: Page): Promise<void> {
   await page.getByRole("button", { name: "Send message", exact: true }).click();
 }
@@ -405,6 +438,22 @@ export async function configureComposerQueueSend(page: Page): Promise<void> {
 /** Drive the real tab chooser's commands even when fullscreen covers its pointer surface.
  * This exercises retained activity changes, not a claim that covered chrome is clickable.
  */
+/** Needs a desktop-width viewport: compact layouts have no keyboard shortcuts. */
+export async function switchComposerTabWithKeyboard(
+  page: Page,
+  direction: "previous" | "next",
+): Promise<void> {
+  await page.keyboard.press(
+    direction === "previous" ? "Alt+Shift+BracketLeft" : "Alt+Shift+BracketRight",
+  );
+}
+export async function expectWorkspaceHeaderHidden(page: Page): Promise<void> {
+  await expect(page.getByTestId("workspace-tab-switcher-trigger")).toHaveCount(0);
+}
+export async function expectWorkspaceHeaderVisible(page: Page): Promise<void> {
+  await expect(page.getByTestId("workspace-tab-switcher-trigger")).toBeVisible();
+}
+
 export async function activateRetainedComposerTab(page: Page, title: string): Promise<void> {
   await page
     .getByTestId("workspace-tab-switcher-trigger")

packages/app/e2e/support/helpers/custom-models.ts

@@ -0,0 +1,37 @@
+import { expect, type Page } from "@playwright/test";
+import { gotoAppShell, openSettings } from "./app";
+import { openSettingsHostSection } from "./settings";
+import { getServerId } from "./server-id";
+
+export async function openCustomModels(page: Page): Promise<void> {
+  await gotoAppShell(page);
+  await openSettings(page);
+  await openSettingsHostSection(page, getServerId(), "providers");
+  await page.getByRole("button", { name: "Claude provider details", exact: true }).click();
+  await expect(page.getByRole("textbox", { name: "Search models" })).toBeVisible();
+}
+
+export async function addCustomModel(page: Page, id: string): Promise<void> {
+  await page.getByRole("button", { name: "Add model", exact: true }).click();
+  await page.getByPlaceholder("e.g. openai/gpt-5").fill(id);
+  await page
+    .getByTestId("add-custom-model-sheet")
+    .getByRole("button", { name: "Add", exact: true })
+    .click();
+  await expect(page.getByRole("button", { name: `Remove ${id}`, exact: true })).toHaveCount(1);
+}
+
+export async function removeCustomModel(page: Page, id: string): Promise<void> {
+  await page.getByRole("textbox", { name: "Search models" }).fill(id);
+  const remove = page.getByRole("button", { name: `Remove ${id}`, exact: true });
+  await expect(remove).toBeInViewport({ ratio: 1 });
+  await remove.click();
+  await expect(remove).toHaveCount(0);
+}
+
+export async function expectCustomModelRetained(page: Page, id: string): Promise<void> {
+  await page.getByRole("textbox", { name: "Search models" }).fill(id);
+  await expect(page.getByRole("button", { name: `Remove ${id}`, exact: true })).toBeInViewport({
+    ratio: 1,
+  });
+}

packages/app/e2e/support/helpers/file-explorer.ts

@@ -1,4 +1,4 @@
-import { expect, type Page } from "@playwright/test";
+import { expect, type Download, type Page } from "@playwright/test";
 import { openFilesPanel } from "./workspace-tabs";
 
 function fileExplorerTree(page: Page) {
@@ -39,3 +39,10 @@ export async function expectFileTabOpen(page: Page, filePath: string): Promise<v
     timeout: 30_000,
   });
 }
+
+export async function downloadFileFromExplorer(page: Page, fileName: string): Promise<Download> {
+  await fileExplorerEntry(page, fileName).click({ button: "right" });
+  const downloaded = page.waitForEvent("download");
+  await page.getByRole("menuitem", { name: "Download", exact: true }).click();
+  return downloaded;
+}

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

@@ -43,6 +43,15 @@ export async function expectQuestionOptionSelected(page: Page, option: string):
   await expect(questionOption(page, option)).toHaveAttribute("aria-checked", "true");
 }
 
+export async function expectQuestionOptionPreview(
+  page: Page,
+  input: { option: string; preview: string },
+): Promise<void> {
+  await expect(
+    questionOption(page, input.option).getByTestId("question-form-option-preview"),
+  ).toContainText(input.preview);
+}
+
 export async function openQuestion(
   page: Page,
   input: { index: number; total: number },

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

@@ -49,31 +49,37 @@ export async function seedParentWithSubagent(
     modeId: "load-test",
     model: "ten-second-stream",
   });
-  const child = await workspace.client.createAgent({
-    provider: "mock",
-    cwd: workspace.repoPath,
-    workspaceId: workspace.workspaceId,
-    title: input.childTitle,
-    modeId: "load-test",
-    model: "ten-second-stream",
-    labels: {
-      [PARENT_AGENT_ID_LABEL]: parent.id,
-    },
-  });
+  const child = await seedSubagent(workspace, { parentId: parent.id, title: input.childTitle });
 
   return {
     parent: {
       id: parent.id,
       title: input.parentTitle,
     },
-    child: {
-      id: child.id,
-      title: input.childTitle,
-    },
+    child,
     workspaceId: workspace.workspaceId,
   };
 }
 
+/** Seeds an idle Paseo subagent of an existing agent in the same workspace. */
+export async function seedSubagent(
+  workspace: Pick<SeededWorkspace, "client" | "repoPath" | "workspaceId">,
+  input: { parentId: string; title: string },
+): Promise<{ id: string; title: string }> {
+  const child = await workspace.client.createAgent({
+    provider: "mock",
+    cwd: workspace.repoPath,
+    workspaceId: workspace.workspaceId,
+    title: input.title,
+    modeId: "load-test",
+    model: "ten-second-stream",
+    labels: {
+      [PARENT_AGENT_ID_LABEL]: input.parentId,
+    },
+  });
+  return { id: child.id, title: input.title };
+}
+
 export async function seedParentWithCrossWorkspaceSubagent(
   workspace: Pick<SeededWorkspace, "client" | "repoPath" | "workspaceId" | "projectId">,
   input: { parentTitle: string; childTitle: string },
@@ -141,6 +147,12 @@ export async function openSubagentsTrack(page: Page): Promise<void> {
   await expect(panel).toBeVisible({ timeout: 30_000 });
 }
 
+/** On compact the track opens as a sheet, which closes once a row is chosen. */
+export async function openSubagentFromCompactTrack(page: Page, childId: string): Promise<void> {
+  await page.getByTestId("subagents-track-header").click();
+  await page.getByTestId(`subagents-track-row-${childId}`).click();
+}
+
 export async function expectSubagentRowVisible(page: Page, childId: string): Promise<void> {
   await expect(page.getByTestId(`subagents-track-row-${childId}`)).toBeVisible({
     timeout: 30_000,

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

@@ -0,0 +1,98 @@
+import { expect, type Locator, type Page } from "@playwright/test";
+
+/** The compact workspace sheet, named after the tab it hosts. */
+export function workspaceSheet(page: Page, label: string): Locator {
+  return page.getByRole("dialog", { name: label });
+}
+
+/** Sheet height as a fraction of the viewport; mirrors the host's 92% snap point. */
+const SHEET_SNAP_FRACTION = 0.92;
+/** The header starts below the sheet's drag indicator, inside the handle. */
+const SHEET_INDICATOR_MAX_HEIGHT = 32;
+
+/**
+ * The sheet rests at its snap point, docked to the bottom edge. A sheet pushed up past it
+ * covers the workspace header; a sheet sunk below it hides content.
+ */
+export async function expectWorkspaceSheetAtSnap(page: Page, label: string): Promise<void> {
+  const viewportHeight = page.viewportSize()?.height ?? 0;
+  const snapTop = Math.round(viewportHeight * (1 - SHEET_SNAP_FRACTION));
+  const sheet = workspaceSheet(page, label);
+  const header = sheet.getByTestId("workspace-sheet-header");
+  const body = sheet.getByTestId("workspace-sheet-body");
+  await expect
+    .poll(async () => {
+      const [headerBox, bodyBox] = await Promise.all([header.boundingBox(), body.boundingBox()]);
+      if (!headerBox || !bodyBox) return null;
+      const top = Math.round(headerBox.y);
+      return {
+        dockedToBottom: Math.round(bodyBox.y + bodyBox.height) === viewportHeight,
+        topAtSnap: top >= snapTop && top <= snapTop + SHEET_INDICATOR_MAX_HEIGHT,
+      };
+    })
+    .toEqual({ dockedToBottom: true, topAtSnap: true });
+}
+
+export async function expectOpenTabCount(page: Page, count: number): Promise<void> {
+  await expect(
+    page.getByRole("button", { name: `Switch tabs (${count} open)` }).filter({ visible: true }),
+  ).toBeVisible();
+}
+
+export async function closeWorkspaceSheet(page: Page, label: string): Promise<void> {
+  const sheet = workspaceSheet(page, label);
+  await sheet.getByRole("button", { name: "Close" }).click();
+  await expect(sheet).toHaveCount(0);
+}
+
+export async function openWorkspaceSheetAsTab(page: Page, label: string): Promise<void> {
+  const sheet = workspaceSheet(page, label);
+  await sheet.getByRole("button", { name: "Open as tab" }).click();
+  await expect(sheet).toHaveCount(0);
+}
+
+export async function replaceWorkspaceSheetFileText(
+  page: Page,
+  label: string,
+  content: string,
+): Promise<void> {
+  const editor = workspaceSheet(page, label)
+    .getByTestId("file-source-editor")
+    .locator(".cm-content");
+  await editor.click();
+  await editor.press("ControlOrMeta+A");
+  await editor.pressSequentially(content);
+}
+
+export async function selectTabFromSwitcher(page: Page, label: string): Promise<void> {
+  await page
+    .getByRole("button", { name: /Switch tabs/ })
+    .filter({ visible: true })
+    .click();
+  const option = page.getByText(label, { exact: true }).filter({ visible: true }).last();
+  await expect(option).toBeVisible();
+  await option.click();
+  await expect(page.getByRole("button", { name: "Bottom sheet backdrop" })).toHaveCount(0);
+}
+
+/** Taps the top sheet's backdrop; each stacked sheet renders its own, top last. */
+export async function tapWorkspaceSheetBackdrop(page: Page): Promise<void> {
+  await page
+    .getByRole("button", { name: "Bottom sheet backdrop" })
+    .last()
+    .click({ position: { x: 10, y: 10 } });
+}
+
+/** Runs a close that hits the unsaved-changes guard, and declines the discard. */
+export async function expectDeclinedDiscardPrompt(
+  page: Page,
+  close: () => Promise<void>,
+): Promise<void> {
+  const prompt = page.waitForEvent("dialog").then(async (dialog) => {
+    const message = dialog.message();
+    await dialog.dismiss();
+    return message;
+  });
+  await close();
+  expect(await prompt).toContain("discard the draft");
+}

packages/app/src/agent-controls/labels.test.ts

@@ -29,4 +29,15 @@ describe("formatThinkingOptionLabel", () => {
     expect(formatThinkingOptionLabel({ id: "think-hard", label: "think-hard" })).toBe("Think hard");
     expect(formatThinkingOptionLabel({ id: "xhigh", label: "XHigh" })).toBe("Extra high");
   });
+
+  it("preserves provider-supplied xhigh labels with extra detail", () => {
+    expect(formatThinkingOptionLabel({ id: "xhigh", label: "XHigh (56 | 8m)" })).toBe(
+      "X high (56 | 8m)",
+    );
+    expect(formatThinkingOptionLabel({ id: "xhigh", label: "XHigh (45 | 6m)" })).toBe(
+      "X high (45 | 6m)",
+    );
+    expect(formatThinkingOptionLabel({ id: "xhigh" })).toBe("Extra high");
+    expect(formatThinkingOptionLabel({ id: "xhigh", label: "Extra high" })).toBe("Extra high");
+  });
 });

packages/app/src/agent-controls/labels.ts

@@ -34,10 +34,9 @@ export function formatAgentModeLabel(mode: ControlLabelInput): string {
 
 export function formatThinkingOptionLabel(option: ControlLabelInput): string {
   const rawLabel = (option.label ?? option.id).trim();
-  const compactId = option.id.replace(/[\s_-]+/g, "").toLowerCase();
   const compactLabel = rawLabel.replace(/[\s_-]+/g, "").toLowerCase();
 
-  if (compactId === "xhigh" || compactLabel === "xhigh") {
+  if (compactLabel === "xhigh" || compactLabel === "extrahigh") {
     return i18n.t("agentControls.thinking.extraHigh");
   }
 

packages/app/src/app/_layout.tsx

@@ -116,6 +116,7 @@ import { usePanelStore } from "@/stores/panel-store";
 import { flushDraftPersistStorage } from "@/stores/draft-store";
 import { getNextThemePreference, ICON_STROKE_WIDTH } from "@/styles/theme";
 import { useSessionStore } from "@/stores/session-store";
+import { WorkspaceLayoutModePublisher } from "@/workspace-tabs/layout-mode-publisher";
 import { installWebScrollbarStyles } from "@/styles/install-web-scrollbar-styles";
 import type { HostProfile } from "@/types/host-connection";
 import {
@@ -549,6 +550,7 @@ function AppContainer({ children, chromeEnabled: chromeEnabledOverride }: AppCon
   }
   const workspaceChrome = (
     <View style={rowStyle}>
+      <WorkspaceLayoutModePublisher />
       {!isCompactLayout ? (
         <WindowChromeRegion corners={appChromeLayout.sidebarCorners}>
           {themedSidebarChrome}
@@ -663,7 +665,7 @@ function MobileGestureWrapper({
 
   return (
     <GestureDetector gesture={openGesture} touchAction={MOBILE_WEB_GESTURE_TOUCH_ACTION}>
-      <View collapsable={false} style={layoutStyles.surfaceFill}>
+      <View collapsable={false} style={layoutStyles.surfaceFill} testID="compact-shell">
         {children}
       </View>
     </GestureDetector>

packages/app/src/app/new.tsx

@@ -1,6 +1,15 @@
 import { useLocalSearchParams } from "expo-router";
+import { useMemo } from "react";
 import { HostRouteBootstrapBoundary } from "@/components/host-route-bootstrap-boundary";
+import {
+  ComposerEditingScope,
+  WorkspaceComposerEditingSessionsProvider,
+} from "@/composer/editing-session";
 import { NewWorkspaceScreen } from "@/screens/new-workspace-screen";
+import { buildNewWorkspaceDraftKey } from "@/stores/draft-keys";
+
+/** New workspace drafts share one editing-session home, keyed like a tab by draft. */
+const NEW_WORKSPACE_SESSIONS_KEY = "new-workspace";
 
 export default function NewWorkspaceRoute() {
   const params = useLocalSearchParams<{
@@ -23,16 +32,28 @@ export default function NewWorkspaceRoute() {
     draftId ?? null,
   ]);
 
+  // The shell remounts this route when the viewport crosses the compact breakpoint;
+  // the draft's editing session (fullscreen, retained caret) lives above the shell.
+  const draftKey = buildNewWorkspaceDraftKey(draftId);
+  const sessionTabIds = useMemo(() => [draftKey], [draftKey]);
+
   return (
     <HostRouteBootstrapBoundary>
-      <NewWorkspaceScreen
-        key={screenKey}
-        serverId={serverId}
-        sourceDirectory={sourceDirectory}
-        displayName={displayName}
-        projectId={projectId}
-        draftId={draftId}
-      />
+      <WorkspaceComposerEditingSessionsProvider
+        workspaceKey={NEW_WORKSPACE_SESSIONS_KEY}
+        tabIds={sessionTabIds}
+      >
+        <ComposerEditingScope tabId={draftKey} targetKey={draftKey}>
+          <NewWorkspaceScreen
+            key={screenKey}
+            serverId={serverId}
+            sourceDirectory={sourceDirectory}
+            displayName={displayName}
+            projectId={projectId}
+            draftId={draftId}
+          />
+        </ComposerEditingScope>
+      </WorkspaceComposerEditingSessionsProvider>
     </HostRouteBootstrapBoundary>
   );
 }

packages/app/src/components/adaptive-modal-sheet.tsx

@@ -1,10 +1,10 @@
 import { useCallback, useEffect, useMemo, useState } from "react";
-import type { ReactNode } from "react";
+import type { ComponentProps, ReactNode } from "react";
 import { createPortal } from "react-dom";
 import { useTranslation } from "react-i18next";
 import { Keyboard, Pressable, Text, View } from "react-native";
 import type { DimensionValue, StyleProp, ViewStyle } from "react-native";
-import { StyleSheet, useUnistyles } from "react-native-unistyles";
+import { StyleSheet, useUnistyles, withUnistyles } from "react-native-unistyles";
 import { useIsCompactFormFactor } from "@/constants/layout";
 import {
   getOverlayRoot,
@@ -12,7 +12,7 @@ import {
   useGlobalWebOverlayLayer,
   useWebOverlayRegistration,
 } from "../lib/overlay-root";
-import { type BottomSheetBackgroundProps } from "@gorhom/bottom-sheet";
+import { BottomSheetHandle, type BottomSheetBackgroundProps } from "@gorhom/bottom-sheet";
 import Animated from "react-native-reanimated";
 import { ArrowLeft, Search, X } from "lucide-react-native";
 import {
@@ -223,7 +223,8 @@ const styles = StyleSheet.create((theme) => ({
 
 const WEB_EXIT_DURATION_MS = 160;
 
-function SheetBackground({ style }: BottomSheetBackgroundProps) {
+/** The compact sheet's surface: Gorhom's `backgroundComponent` for every bottom sheet. */
+export function SheetBackground({ style }: BottomSheetBackgroundProps) {
   const { theme } = useUnistyles();
   const combinedStyle = useMemo(
     () => [
@@ -239,6 +240,39 @@ function SheetBackground({ style }: BottomSheetBackgroundProps) {
   return <Animated.View pointerEvents="none" style={combinedStyle} />;
 }
 
+const ThemedBottomSheetHandle = withUnistyles(BottomSheetHandle, (theme) => ({
+  indicatorStyle: { backgroundColor: theme.colors.palette.zinc[600] },
+}));
+
+const HANDLE_WITH_CONTENT_STYLE = { paddingHorizontal: 0, paddingBottom: 0 };
+
+/**
+ * The compact sheet's drag handle: Gorhom's `handleComponent` for every bottom sheet. Children
+ * join the handle, so a header passed here drags the sheet like the indicator does. That is how a
+ * sheet whose content scrolls on its own keeps its header draggable without content panning.
+ */
+export function SheetHandle({
+  children,
+  // Gorhom passes `indicatorStyle={undefined}`, which would override the themed indicator.
+  indicatorStyle: _indicatorStyle,
+  ...props
+}: ComponentProps<typeof BottomSheetHandle>) {
+  if (!children) return <ThemedBottomSheetHandle {...props} />;
+  // The children carry their own semantics; the handle's slider role would swallow them on web.
+  return (
+    <ThemedBottomSheetHandle
+      {...props}
+      style={HANDLE_WITH_CONTENT_STYLE}
+      accessible={false}
+      accessibilityRole={null}
+      accessibilityLabel={null}
+      accessibilityHint={null}
+    >
+      {children}
+    </ThemedBottomSheetHandle>
+  );
+}
+
 /**
  * The sheet body, indented to the sheet's content inset.
  *
@@ -449,7 +483,6 @@ export function AdaptiveModalSheet({
   bodyStyle,
   contextBridge = null,
 }: AdaptiveModalSheetProps) {
-  const { theme } = useUnistyles();
   const { t } = useTranslation();
   const isMobile = useIsCompactFormFactor();
   const insets = useSafeAreaInsets();
@@ -481,10 +514,6 @@ export function AdaptiveModalSheet({
       ) : null,
     [footer, footerClearanceStyle, footerContainerStyle],
   );
-  const handleIndicatorStyle = useMemo(
-    () => ({ backgroundColor: theme.colors.palette.zinc[600] }),
-    [theme.colors.palette.zinc],
-  );
   useEffect(() => {
     if (!isWeb && visible) {
       // A newly opened sheet owns input. A keyboard belonging to the sheet below
@@ -600,7 +629,7 @@ export function AdaptiveModalSheet({
         backdropOpacity={0.45}
         enablePanDownToClose
         backgroundComponent={SheetBackground}
-        handleIndicatorStyle={handleIndicatorStyle}
+        handleComponent={SheetHandle}
         keyboardBehavior="extend"
         keyboardBlurBehavior="restore"
         accessible={false}

packages/app/src/components/left-sidebar.tsx

@@ -35,6 +35,7 @@ import { SidebarNavRows } from "@/components/sidebar/sidebar-nav-rows";
 import { SidebarHelpMenu } from "@/components/sidebar/sidebar-help-menu";
 import { SidebarResizeHandle } from "@/components/sidebar-resize-handle";
 import { DensityIcon } from "@/components/ui/density-icon";
+import { SidebarSectionHeader } from "@/components/sidebar/sidebar-section-header";
 import { Shortcut } from "@/components/ui/shortcut";
 import { Tooltip, TooltipContent, TooltipTrigger } from "@/components/ui/tooltip";
 import { HEADER_INNER_HEIGHT, useIsCompactFormFactor } from "@/constants/layout";
@@ -805,21 +806,18 @@ function DesktopSidebar({
 
 function WorkspacesSectionHeader() {
   return (
-    <View style={styles.workspacesSectionHeader}>
-      <Text style={styles.workspacesSectionTitle}>Workspaces</Text>
-      <View style={styles.workspacesSectionActions}>
-        <Tooltip delayDuration={300}>
-          <TooltipTrigger asChild>
-            <View>
-              <SidebarDisplayPreferencesMenu />
-            </View>
-          </TooltipTrigger>
-          <TooltipContent side="bottom" align="center" offset={8}>
-            <IconTooltipContent label="Display preferences" />
-          </TooltipContent>
-        </Tooltip>
-      </View>
-    </View>
+    <SidebarSectionHeader title="Workspaces">
+      <Tooltip delayDuration={300}>
+        <TooltipTrigger asChild>
+          <View>
+            <SidebarDisplayPreferencesMenu />
+          </View>
+        </TooltipTrigger>
+        <TooltipContent side="bottom" align="center" offset={8}>
+          <IconTooltipContent label="Display preferences" />
+        </TooltipContent>
+      </Tooltip>
+    </SidebarSectionHeader>
   );
 }
 
@@ -850,29 +848,6 @@ const styles = StyleSheet.create((theme) => ({
   sidebarHeaderGroupBelowChrome: {
     paddingTop: 0,
   },
-  workspacesSectionHeader: {
-    flexDirection: "row",
-    alignItems: "center",
-    justifyContent: "space-between",
-    gap: theme.spacing[2],
-    // Rendered inside the scroll's listContent (paddingHorizontal spacing[2]). The title
-    // lands at spacing[2] left to align with project icons. Settings2's painted path stops
-    // inside its 14px SVG, so 4px aligns the ink rather than the SVG box to the row rail.
-    paddingLeft: theme.spacing[2],
-    paddingRight: 4,
-    paddingTop: theme.spacing[1],
-    paddingBottom: theme.spacing[1],
-  },
-  workspacesSectionTitle: {
-    color: theme.colors.foregroundMuted,
-    fontSize: theme.fontSize.sm,
-    fontWeight: theme.fontWeight.normal,
-  },
-  workspacesSectionActions: {
-    flexDirection: "row",
-    alignItems: "center",
-    gap: theme.spacing[1],
-  },
   sidebarContent: {
     flex: 1,
     minHeight: 0,

packages/app/src/components/markdown/html-ish.test.ts

@@ -3,6 +3,71 @@ import { describe, expect, it } from "vitest";
 import { normalizeHtmlishMarkdown, splitHtmlishMarkdown } from "./html-ish";
 
 describe("splitHtmlishMarkdown", () => {
+  it("renders heading text beside a linked picture without literal heading tags", () => {
+    const source =
+      '<h2><a href="https://example.com/r"><picture><source srcset="https://example.com/d.svg"><img alt="Retrigger" src="https://example.com/l.svg"></picture></a>Confidence Score: 5/5</h2>';
+
+    expect(splitHtmlishMarkdown(source)).toEqual([
+      {
+        kind: "inlineImage",
+        alt: "Retrigger",
+        src: "https://example.com/l.svg",
+        href: "https://example.com/r",
+        flowsWithText: true,
+      },
+      { kind: "markdown", text: "Confidence Score: 5/5" },
+    ]);
+  });
+
+  it.each(["h1", "h2", "h3", "h4", "h5", "h6"])(
+    "keeps a mixed %s heading together after preceding markdown",
+    (heading) => {
+      const source = `Intro\n\n<${heading}><img alt="Icon" src="https://example.com/icon.svg">Caption</${heading}>\n\nOutro`;
+
+      expect(splitHtmlishMarkdown(source)).toEqual([
+        { kind: "markdown", text: "Intro\n\n" },
+        {
+          kind: "inlineImage",
+          alt: "Icon",
+          src: "https://example.com/icon.svg",
+          flowsWithText: true,
+        },
+        { kind: "markdown", text: "Caption\n\nOutro" },
+      ]);
+    },
+  );
+
+  it("preserves formatted text before and after images in a details heading", () => {
+    const source =
+      '<details><summary>More</summary><h2><strong>Before</strong><img alt="Icon" src="https://example.com/icon.svg"><em>After</em></h2></details>';
+
+    expect(splitHtmlishMarkdown(source)).toEqual([
+      {
+        kind: "details",
+        summary: "More",
+        body: "**Before***After*",
+        bodyParts: [
+          { kind: "markdown", text: "**Before**" },
+          { kind: "inlineImage", alt: "Icon", src: "https://example.com/icon.svg" },
+          { kind: "markdown", text: "*After*" },
+        ],
+      },
+    ]);
+  });
+
+  it("keeps mixed HTML headings literal in code examples", () => {
+    const heading = '<h2><img src="https://example.com/icon.svg">Caption</h2>';
+    const source = `Use \`${heading}\`\n\n\`\`\`html\n${heading}\n\`\`\``;
+
+    expect(splitHtmlishMarkdown(source)).toEqual([{ kind: "markdown", text: source }]);
+  });
+
+  it("preserves unknown wrappers around text-only headings", () => {
+    expect(splitHtmlishMarkdown("<section><h2>Heading</h2></section>")).toEqual([
+      { kind: "markdown", text: "<section>Heading</section>" },
+    ]);
+  });
+
   const inlineImageBody = [
     '<a href="#"><img alt="Priority" src="https://example.com/assets/priority.svg?v=9" align="top"></a> Spoofed browser User-Agent allows access control bypass',
     "",

packages/app/src/components/markdown/html-ish.ts

@@ -125,9 +125,20 @@ function splitHtmlishTokens(tokens: HtmlToken[]): MarkdownDisplayPart[] {
       continue;
     }
 
-    const nextDetailsIndex = findNextOpenTag(tokens, cursor + 1, "details");
-    const nextInlineImageIndex = findNextInlineImageIndex(tokens, cursor + 1);
-    const end = Math.min(nextDetailsIndex ?? tokens.length, nextInlineImageIndex ?? tokens.length);
+    if (isHeadingTag(token)) {
+      const closeIndex = findMixedHeadingClose(tokens, cursor);
+      if (closeIndex !== null) {
+        // Headings render as their contents. Split those contents together so an
+        // embedded image cannot strand the opening heading tag in a text slice.
+        for (const part of splitHtmlishTokens(tokens.slice(cursor + 1, closeIndex))) {
+          appendDisplayPart(parts, part);
+        }
+        cursor = closeIndex + 1;
+        continue;
+      }
+    }
+
+    const end = findNextDisplayPartIndex(tokens, cursor + 1) ?? tokens.length;
     appendMarkdownPart(parts, renderInlineTokens(tokens.slice(cursor, end)));
     cursor = end;
   }
@@ -259,15 +270,44 @@ function flowsWithFollowingText(tokens: HtmlToken[], start: number, end: number)
   return false;
 }
 
-function findNextInlineImageIndex(tokens: HtmlToken[], start: number): number | null {
+function findNextDisplayPartIndex(tokens: HtmlToken[], start: number): number | null {
   for (let index = start; index < tokens.length; index += 1) {
-    if (parseInlineImageAt(tokens, index)) {
+    if (
+      isOpenTag(tokens[index], "details") ||
+      findMixedHeadingClose(tokens, index) !== null ||
+      parseInlineImageAt(tokens, index)
+    ) {
       return index;
     }
   }
   return null;
 }
 
+function findMixedHeadingClose(tokens: HtmlToken[], start: number): number | null {
+  const token = tokens[start];
+  if (!isHeadingTag(token)) {
+    return null;
+  }
+  const closeIndex = findMatchingClose(tokens, start, token.name);
+  if (closeIndex === null) {
+    return null;
+  }
+  for (let index = start + 1; index < closeIndex; index += 1) {
+    if (parseInlineImageAt(tokens, index)) {
+      return closeIndex;
+    }
+  }
+  return null;
+}
+
+function appendDisplayPart(parts: MarkdownDisplayPart[], part: MarkdownDisplayPart): void {
+  if (part.kind === "markdown") {
+    appendMarkdownPart(parts, part.text);
+  } else {
+    parts.push(part);
+  }
+}
+
 function appendMarkdownPart(parts: MarkdownDisplayPart[], text: string): void {
   if (!text) {
     return;

packages/app/src/components/provider-diagnostic-sheet.tsx

@@ -95,11 +95,11 @@ function CustomModelRow({
 
   return (
     <View style={sheetStyles.modelRow}>
-      <Text style={sheetStyles.modelTitle} numberOfLines={1}>
+      <Text style={[sheetStyles.modelTitle, sheetStyles.customModelText]} numberOfLines={1}>
         {model.label}
       </Text>
       <Text
-        style={sheetStyles.monoHint}
+        style={[sheetStyles.monoHint, sheetStyles.customModelText]}
         numberOfLines={1}
         selectable
         dataSet={CODE_SURFACE_DATASET}
@@ -762,6 +762,7 @@ const sheetStyles = StyleSheet.create((theme) => ({
   iconButton: {
     width: 28,
     height: 28,
+    flexShrink: 0,
     borderRadius: theme.borderRadius.full,
     alignItems: "center",
     justifyContent: "center",
@@ -807,6 +808,10 @@ const sheetStyles = StyleSheet.create((theme) => ({
     fontSize: theme.fontSize.base,
     flexShrink: 0,
   },
+  customModelText: {
+    flexShrink: 1,
+    minWidth: 0,
+  },
   modelRowFiller: {
     flex: 1,
   },

packages/app/src/components/question-form-card-core.test.ts

@@ -147,4 +147,29 @@ describe("question form card core", () => {
       Response: "custom",
     });
   });
+
+  test("keeps option previews so options can be compared", () => {
+    const questions = parseQuestionFormQuestions({
+      questions: [
+        {
+          question: "Which layout?",
+          header: "Layout",
+          options: [
+            {
+              label: "Tabs",
+              description: "One tab per section",
+              preview: "<Tabs>\n  <Tab />\n</Tabs>",
+            },
+            { label: "Single page" },
+          ],
+          multiSelect: false,
+        },
+      ],
+    });
+
+    expect(questions?.[0]?.options).toEqual([
+      { label: "Tabs", description: "One tab per section", preview: "<Tabs>\n  <Tab />\n</Tabs>" },
+      { label: "Single page", description: undefined, preview: undefined },
+    ]);
+  });
 });

packages/app/src/components/question-form-card-core.ts

@@ -1,6 +1,7 @@
 export interface QuestionOption {
   label: string;
   description?: string;
+  preview?: string;
 }
 
 export interface QuestionFormQuestion {
@@ -46,6 +47,7 @@ export function parseQuestionFormQuestions(input: unknown): QuestionFormQuestion
       options.push({
         label: o.label,
         description: typeof o.description === "string" ? o.description : undefined,
+        preview: readOptionalString(o, "preview"),
       });
     }
     questions.push({

packages/app/src/components/question-form-card.tsx

@@ -10,6 +10,7 @@ import type { AgentPermissionResponse } from "@getpaseo/protocol/agent-types";
 import { isWeb } from "@/constants/platform";
 import { EditingTextInput as TextInput } from "@/components/ui/text-input";
 import type { EditingTextInputHandle } from "@/components/ui/text-input/types";
+import { ScrollableCodeSurface } from "@/components/ui/scrollable-code-surface";
 import {
   areQuestionsAnswered,
   buildQuestionFormAnswers,
@@ -29,6 +30,9 @@ interface QuestionFormCardProps {
 }
 
 const IS_WEB = isWeb;
+// Native previews are uncapped: inside the option's Pressable, Android never hands a
+// drag to the preview's nested scroll, so lines past a cap would be unreachable.
+const OPTION_PREVIEW_MAX_HEIGHT = IS_WEB ? 240 : undefined;
 
 function getQuestionInputPlaceholder({
   question,
@@ -133,6 +137,20 @@ function QuestionOptionRow({
           {option.description ? (
             <Text style={optionDescriptionStyle}>{option.description}</Text>
           ) : null}
+          {option.preview ? (
+            // Shown for every option at once so they can be compared before picking.
+            // Long lines wrap, as in Claude Code, since most previews are prose.
+            <ScrollableCodeSurface
+              tone="surface0"
+              maxHeight={OPTION_PREVIEW_MAX_HEIGHT}
+              horizontal={false}
+              selectable={false}
+              textStyle={styles.optionPreviewText}
+              testID="question-form-option-preview"
+            >
+              {option.preview}
+            </ScrollableCodeSurface>
+          ) : null}
         </View>
       </View>
     </Pressable>
@@ -704,6 +722,10 @@ const styles = StyleSheet.create((theme) => ({
     fontSize: theme.fontSize.base,
     lineHeight: 20,
   },
+  optionPreviewText: {
+    lineHeight: 20,
+    ...(isWeb ? { whiteSpace: "pre-wrap", overflowWrap: "break-word" } : null),
+  },
   selectionControl: {
     width: 18,
     height: 18,

packages/app/src/components/sidebar-workspace-list.tsx

@@ -30,7 +30,7 @@ import {
   type ActiveWorkspaceSelection,
 } from "@/stores/navigation-active-workspace-store";
 import { StyleSheet, withUnistyles } from "react-native-unistyles";
-import { density, densityFontSize, densityIconBox } from "@/styles/density";
+import { density, densityIconBox } from "@/styles/density";
 import type { Theme } from "@/styles/theme";
 import type { SidebarSurfaceBackdrop } from "@/styles/surface-backdrop";
 import { getSidebarRowBackdrop } from "@/components/sidebar/sidebar-row-backdrop";
@@ -93,7 +93,7 @@ import {
   SidebarWorkspaceMenu,
 } from "@/components/sidebar/sidebar-workspace-menu";
 import { useLongPressDragInteraction } from "@/components/sidebar/use-long-press-drag-interaction";
-import { PinnedSectionHeader } from "@/components/sidebar/pinned-section-header";
+import { SidebarSectionHeader } from "@/components/sidebar/sidebar-section-header";
 import { SidebarGroupToggleRow } from "@/components/sidebar/sidebar-group-toggle-row";
 import { useLimitedSidebarGroup } from "@/components/sidebar/use-limited-sidebar-group";
 import {
@@ -2114,6 +2114,7 @@ function ProjectModeList({
   onToggleWorkspacePin: ToggleSidebarWorkspacePin;
   onPinnedWorkspaceReorder: (workspaces: SidebarWorkspacePlacement[]) => void;
 }) {
+  const { t } = useTranslation();
   const hasActiveHostFilter = useSidebarViewStore((state) => state.hostFilters.length > 0);
   const [creatingWorkspaceIds, setCreatingWorkspaceIds] = useState<Set<string>>(() => new Set());
   const creatingWorkspaceTimeoutsRef = useRef<Map<string, ReturnType<typeof setTimeout>>>(
@@ -2413,7 +2414,12 @@ function ProjectModeList({
     <>
       {pinnedChats.length > 0 ? (
         <View style={styles.pinnedSection} testID="sidebar-pinned-section">
-          <PinnedSectionHeader collapsed={pinnedCollapsed} onToggle={togglePinnedCollapsed} />
+          <SidebarSectionHeader
+            title={t("sidebar.pinned.title")}
+            collapsed={pinnedCollapsed}
+            onToggle={togglePinnedCollapsed}
+            testID="sidebar-pinned-section-header"
+          />
           {pinnedCollapsed ? null : (
             <>
               <DraggableList
@@ -2550,12 +2556,12 @@ const styles = StyleSheet.create((theme) => ({
   },
   newWorkspaceGhostText: {
     color: theme.colors.foregroundMuted,
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     minWidth: 0,
     flexShrink: 1,
   },
   newWorkspaceGhostTextHovered: {
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     minWidth: 0,
     flexShrink: 1,
     color: theme.colors.foreground,
@@ -2603,7 +2609,7 @@ const styles = StyleSheet.create((theme) => ({
   },
   projectTitle: {
     color: theme.colors.foregroundMuted,
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     fontWeight: "400",
     minWidth: 0,
     flexShrink: 1,

packages/app/src/components/sidebar/pinned-section-header.tsx

@@ -1,62 +0,0 @@
-import { useMemo } from "react";
-import { useTranslation } from "react-i18next";
-import { ChevronDown, ChevronRight } from "lucide-react-native";
-import { Pressable, Text } from "react-native";
-import { StyleSheet } from "react-native-unistyles";
-import { DensityIcon } from "@/components/ui/density-icon";
-import { useIsCompactFormFactor } from "@/constants/layout";
-import { isNative } from "@/constants/platform";
-import { density, densityFontSize } from "@/styles/density";
-
-export function PinnedSectionHeader({
-  collapsed,
-  onToggle,
-}: {
-  collapsed: boolean;
-  onToggle: () => void;
-}) {
-  const { t } = useTranslation();
-  const isCompact = useIsCompactFormFactor();
-  const accessibilityState = useMemo(() => ({ expanded: !collapsed }), [collapsed]);
-
-  return (
-    <Pressable
-      accessibilityRole="button"
-      accessibilityState={accessibilityState}
-      onPress={onToggle}
-      style={styles.header}
-      testID="sidebar-pinned-section-header"
-    >
-      {({ hovered }) => (
-        <>
-          <Text style={styles.title}>{t("sidebar.pinned.title")}</Text>
-          {hovered || isNative || isCompact ? (
-            <DensityIcon
-              icon={collapsed ? ChevronRight : ChevronDown}
-              size="xs"
-              color="foregroundMuted"
-            />
-          ) : null}
-        </>
-      )}
-    </Pressable>
-  );
-}
-
-const styles = StyleSheet.create((theme) => ({
-  header: {
-    minHeight: density.rowHeight,
-    flexDirection: "row",
-    alignItems: "center",
-    alignSelf: "flex-start",
-    gap: theme.spacing[1],
-    paddingHorizontal: theme.spacing[2],
-    paddingVertical: theme.spacing[1],
-    userSelect: "none",
-  },
-  title: {
-    color: theme.colors.foregroundMuted,
-    fontSize: densityFontSize(theme, "sm"),
-    fontWeight: theme.fontWeight.normal,
-  },
-}));

packages/app/src/components/sidebar/project-leading-visual.tsx

@@ -4,7 +4,7 @@ import { useTranslation } from "react-i18next";
 import { ChevronDown, ChevronRight, CircleAlert } from "lucide-react-native";
 import { ProjectIconView } from "@/components/project-icon-view";
 import { getStatusBucketLabel } from "@/hooks/sidebar-status-view-model";
-import { density, densityIconBox, densityIconProps } from "@/styles/density";
+import { densityIconBox, densityIconProps } from "@/styles/density";
 import type { Theme } from "@/styles/theme";
 import type { SidebarStateBucket } from "@/utils/sidebar-agent-state";
 import {
@@ -24,6 +24,9 @@ import type { SidebarSurfaceBackdrop } from "@/styles/surface-backdrop";
 
 // Every surfaced status shares one badge shell, so the badge never changes size or position
 // between states. Only the thing inside it changes.
+// Matches the workspace title's lineHeight (sidebar-workspace-row-content's
+// workspaceBranchText) so the icon centers on the title rather than floating above it.
+const LEADING_SLOT_HEIGHT = 20;
 const STATUS_BADGE_SIZE = 12;
 // How far the badge overhangs the icon's bottom-right corner. Well short of half the badge:
 // centered on the corner it reads as hanging off the icon rather than sitting on it, and the
@@ -273,10 +276,10 @@ const styles = StyleSheet.create((theme) => {
     // The slot is as tall as the title's line box, not as tall as the icon, and centers the
     // icon inside it. Rows lay their leading visual out with alignItems:flex-start, so a slot
     // only as tall as the icon puts it above the title and the kebab — which is why the
-    // workspace status indicator shares the same `rowLineHeight`.
+    // workspace status indicator is as tall as `LEADING_SLOT_HEIGHT`.
     projectLeadingVisualSlot: {
       width: densityIconBox("md"),
-      height: density.rowLineHeight,
+      height: LEADING_SLOT_HEIGHT,
       flexShrink: 0,
       alignItems: "center",
       justifyContent: "center",

packages/app/src/components/sidebar/sidebar-group-toggle-row.tsx

@@ -6,7 +6,7 @@ import { StyleSheet } from "react-native-unistyles";
 import { isWeb } from "@/constants/platform";
 import { sidebarWorkspaceRowStyles } from "@/components/sidebar/sidebar-workspace-row-content";
 import { DensityIcon } from "@/components/ui/density-icon";
-import { density, densityFontSize, densityIconBox } from "@/styles/density";
+import { density, densityIconBox } from "@/styles/density";
 
 /**
  * The row that ends a truncated group. It is a workspace row that happens to say "Show more", so
@@ -100,13 +100,13 @@ const styles = StyleSheet.create((theme) => ({
   },
   text: {
     color: theme.colors.foregroundMuted,
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     minWidth: 0,
     flexShrink: 1,
   },
   textHovered: {
     color: theme.colors.foreground,
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     minWidth: 0,
     flexShrink: 1,
   },

packages/app/src/components/sidebar/sidebar-header-row.tsx

@@ -4,7 +4,7 @@ import { StyleSheet } from "react-native-unistyles";
 import { HEADER_INNER_HEIGHT, HEADER_INNER_HEIGHT_MOBILE } from "@/constants/layout";
 import { DensityIcon } from "@/components/ui/density-icon";
 import { Shortcut } from "@/components/ui/shortcut";
-import { density, densityFontSize, densityIconBox } from "@/styles/density";
+import { density, densityIconBox } from "@/styles/density";
 import type { ShortcutKey } from "@/utils/format-shortcut";
 
 type SidebarHeaderRowVariant = "header" | "compact" | "inline";
@@ -152,7 +152,7 @@ const styles = StyleSheet.create((theme) => ({
   iconSpacerCompact: { width: densityIconBox("sm"), height: densityIconBox("sm") },
   label: {
     flexShrink: 1,
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     fontWeight: theme.fontWeight.normal,
     color: theme.colors.foregroundMuted,
   },

packages/app/src/components/sidebar/sidebar-section-header.tsx

@@ -0,0 +1,115 @@
+import { useMemo, type ReactNode } from "react";
+import { ChevronDown, ChevronRight } from "lucide-react-native";
+import { Pressable, Text, View } from "react-native";
+import { StyleSheet } from "react-native-unistyles";
+import { DensityIcon } from "@/components/ui/density-icon";
+import { useIsCompactFormFactor } from "@/constants/layout";
+import { isNative } from "@/constants/platform";
+import { density } from "@/styles/density";
+
+/** A sidebar section label such as "Pinned" or "Workspaces". A section with `onToggle`
+ * collapses from its title; children sit at the trailing edge as its actions. */
+export function SidebarSectionHeader({
+  title,
+  collapsed,
+  onToggle,
+  testID,
+  children,
+}: {
+  title: string;
+  collapsed?: boolean;
+  onToggle?: () => void;
+  testID?: string;
+  children?: ReactNode;
+}) {
+  return (
+    <View style={styles.header}>
+      {onToggle ? (
+        <CollapsibleTitle
+          title={title}
+          collapsed={collapsed ?? false}
+          onToggle={onToggle}
+          testID={testID}
+        />
+      ) : (
+        <Text style={styles.title} testID={testID}>
+          {title}
+        </Text>
+      )}
+      {children ? <View style={styles.actions}>{children}</View> : null}
+    </View>
+  );
+}
+
+function CollapsibleTitle({
+  title,
+  collapsed,
+  onToggle,
+  testID,
+}: {
+  title: string;
+  collapsed: boolean;
+  onToggle: () => void;
+  testID?: string;
+}) {
+  const isCompact = useIsCompactFormFactor();
+  const accessibilityState = useMemo(() => ({ expanded: !collapsed }), [collapsed]);
+
+  return (
+    <Pressable
+      accessibilityRole="button"
+      accessibilityState={accessibilityState}
+      onPress={onToggle}
+      style={styles.toggle}
+      testID={testID}
+    >
+      {({ hovered }) => (
+        <>
+          <Text style={styles.title}>{title}</Text>
+          {hovered || isNative || isCompact ? (
+            <DensityIcon
+              icon={collapsed ? ChevronRight : ChevronDown}
+              size="xs"
+              color="foregroundMuted"
+            />
+          ) : null}
+        </>
+      )}
+    </Pressable>
+  );
+}
+
+const styles = StyleSheet.create((theme) => ({
+  header: {
+    minHeight: density.rowHeight,
+    flexDirection: "row",
+    alignItems: "center",
+    justifyContent: "space-between",
+    gap: theme.spacing[2],
+    // The title lands at spacing[2] to align with the rows' leading icons. Trailing actions
+    // are icon buttons whose painted glyph stops inside the SVG box, so 4px aligns the ink
+    // rather than the box to the row rail.
+    paddingLeft: theme.spacing[2],
+    paddingRight: 4,
+    userSelect: "none",
+  },
+  // The toggle reaches back over the header's leading padding so the whole label edge is pressable.
+  toggle: {
+    alignSelf: "stretch",
+    flexDirection: "row",
+    alignItems: "center",
+    gap: theme.spacing[1],
+    marginLeft: -theme.spacing[2],
+    paddingHorizontal: theme.spacing[2],
+  },
+  title: {
+    color: theme.colors.foregroundMuted,
+    fontSize: theme.fontSize.sm,
+    fontWeight: theme.fontWeight.normal,
+  },
+  actions: {
+    flexDirection: "row",
+    alignItems: "center",
+    gap: theme.spacing[1],
+  },
+}));

packages/app/src/components/sidebar/sidebar-status-list.tsx

@@ -28,7 +28,7 @@ import type { HostBadgeModel } from "@/hosts/appearance";
 import { isWeb as platformIsWeb, isNative as platformIsNative } from "@/constants/platform";
 import { useIsCompactFormFactor } from "@/constants/layout";
 import { StyleSheet } from "react-native-unistyles";
-import { density, densityFontSize, densityIconBox, densityIconProps } from "@/styles/density";
+import { density, densityIconBox, densityIconProps } from "@/styles/density";
 import type { SidebarSurfaceBackdrop } from "@/styles/surface-backdrop";
 import { withUnistyles } from "react-native-unistyles";
 import {
@@ -73,7 +73,7 @@ import {
   SidebarWorkspaceContextMenu,
   SidebarWorkspaceMenu,
 } from "@/components/sidebar/sidebar-workspace-menu";
-import { PinnedSectionHeader } from "@/components/sidebar/pinned-section-header";
+import { SidebarSectionHeader } from "@/components/sidebar/sidebar-section-header";
 import { SidebarGroupToggleRow } from "@/components/sidebar/sidebar-group-toggle-row";
 import { useLimitedSidebarGroup } from "@/components/sidebar/use-limited-sidebar-group";
 import type { ToggleSidebarWorkspacePin } from "@/hooks/use-sidebar-workspace-pin";
@@ -146,6 +146,7 @@ export function SidebarStatusWorkspaceList({
   parentGestureRef,
   dragGestureHostActive,
 }: StatusWorkspaceListProps) {
+  const { t } = useTranslation();
   const collapsedWorkspaceGroupKeys = useSidebarCollapsedSectionsStore(
     (state) => state.collapsedWorkspaceGroupKeys,
   );
@@ -202,7 +203,12 @@ export function SidebarStatusWorkspaceList({
     <>
       {pinnedWorkspaces.length > 0 ? (
         <View style={styles.pinnedSection} testID="sidebar-pinned-section">
-          <PinnedSectionHeader collapsed={pinnedCollapsed} onToggle={togglePinnedCollapsed} />
+          <SidebarSectionHeader
+            title={t("sidebar.pinned.title")}
+            collapsed={pinnedCollapsed}
+            onToggle={togglePinnedCollapsed}
+            testID="sidebar-pinned-section-header"
+          />
           {pinnedCollapsed ? null : (
             <>
               <DraggableList
@@ -1099,7 +1105,7 @@ const styles = StyleSheet.create((theme) => ({
   },
   statusGroupTitle: {
     color: theme.colors.foregroundMuted,
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     fontWeight: "400",
     minWidth: 0,
     flexShrink: 1,

packages/app/src/components/sidebar/sidebar-workspace-row-content.tsx

@@ -16,7 +16,7 @@ import {
   type SidebarWorkspaceTrailing,
 } from "@/components/sidebar/workspace-trailing";
 import { useAppSettings } from "@/hooks/use-settings";
-import { density, densityFontSize, densityIconBox } from "@/styles/density";
+import { densityIconBox } from "@/styles/density";
 import type { Theme } from "@/styles/theme";
 import type { SidebarStateBucket } from "@/utils/sidebar-agent-state";
 import { getStatusDotColor } from "@/utils/status-dot-color";
@@ -453,6 +453,9 @@ export function SidebarWorkspaceTrailingActionOverlay({
   );
 }
 
+// The status dot centres on the title's first line, so both share its line height.
+const TITLE_LINE_HEIGHT = 20;
+
 const styles = StyleSheet.create((theme) => ({
   workspaceRowContent: {
     position: "relative",
@@ -481,7 +484,7 @@ const styles = StyleSheet.create((theme) => ({
   workspaceStatusDot: {
     position: "relative",
     width: densityIconBox("md"),
-    height: density.rowLineHeight,
+    height: TITLE_LINE_HEIGHT,
     borderRadius: theme.borderRadius.full,
     flexShrink: 0,
     alignItems: "center",
@@ -513,9 +516,9 @@ const styles = StyleSheet.create((theme) => ({
   // to the meta row, so it takes the full width the trailing slot leaves behind.
   workspaceBranchText: {
     color: theme.colors.foreground,
-    fontSize: densityFontSize(theme, "base"),
+    fontSize: theme.fontSize.base,
     fontWeight: "400",
-    lineHeight: density.rowLineHeight,
+    lineHeight: TITLE_LINE_HEIGHT,
     opacity: 0.76,
     flex: 1,
     minWidth: 0,

packages/app/src/components/ui/isolated-bottom-sheet-modal/index.tsx

@@ -154,3 +154,4 @@ export function useIsolatedBottomSheetVisibility({
 }
 
 export { SheetVisibleFrame } from "./visible-frame";
+export { systemBackPress } from "./back-press";

packages/app/src/components/ui/text-input/text-input.native.tsx

@@ -104,6 +104,13 @@ export const EditingTextInput = forwardRef<EditingTextInputHandle, EditingTextIn
           });
           if (selection) inputRef.current?.setSelection?.(selection.start, selection.end);
         },
+        setSelection: (selection) => {
+          if (inputRef.current?.setSelection) {
+            inputRef.current.setSelection(selection.start, selection.end);
+            return;
+          }
+          inputRef.current?.setNativeProps?.({ selection });
+        },
         reset: () => {
           textRef.current = "";
           const autoFocus = inputRef.current?.isFocused?.() ?? false;

packages/app/src/components/ui/text-input/text-input.web.tsx

@@ -77,6 +77,10 @@ export const EditingTextInput = forwardRef<EditingTextInputHandle, EditingTextIn
             input.setSelectionRange(selection.start, selection.end);
           }
         },
+        setSelection: (selection) => {
+          const input = inputRef.current as WebTextInputElement | null;
+          input?.setSelectionRange?.(selection.start, selection.end);
+        },
         reset: () => {
           textRef.current = "";
           const input = inputRef.current as WebTextInputElement | null;

packages/app/src/components/ui/text-input/types.ts

@@ -8,6 +8,7 @@ export interface EditingTextInputHandle {
   isFocused(): boolean;
   getText(): string;
   replaceText(text: string, selection?: { start: number; end: number }): void;
+  setSelection(selection: { start: number; end: number }): void;
   /** Clear the editor and reset its intrinsic layout, preserving focus intent. */
   reset(): void;
   getNativeRef(): unknown;

packages/app/src/components/workspace-setup-dialog.tsx

@@ -125,8 +125,7 @@ function buildCreateAgentOptions({
   provider,
 }: {
   composerState: {
-    modeOptions: { id: string }[];
-    selectedMode: string;
+    effectiveModeId: string;
     effectiveModelId: string | null;
     effectiveThinkingOptionId: string | null;
   };
@@ -137,20 +136,11 @@ function buildCreateAgentOptions({
   workspaceId: string;
   provider: CreateAgentRequestOptions["provider"];
 }): CreateAgentRequestOptions {
-  // Reconcile the selected mode against the discovered modes. The mode picker
-  // shows modeOptions[0] when the stored mode isn't in the list (e.g. a stale
-  // globally-remembered mode this workspace's provider config no longer
-  // defines), so the submitted mode must match that display rather than send a
-  // stale mode the provider would reject.
-  const modeOptionIds = composerState.modeOptions.map((mode) => mode.id);
-  const reconciledMode = modeOptionIds.includes(composerState.selectedMode)
-    ? composerState.selectedMode
-    : (modeOptionIds[0] ?? "");
   return {
     provider,
     cwd: workspaceDirectory,
     workspaceId,
-    ...(reconciledMode !== "" ? { modeId: reconciledMode } : {}),
+    ...(composerState.effectiveModeId ? { modeId: composerState.effectiveModeId } : {}),
     ...(composerState.effectiveModelId ? { model: composerState.effectiveModelId } : {}),
     ...(composerState.effectiveThinkingOptionId
       ? { thinkingOptionId: composerState.effectiveThinkingOptionId }

packages/app/src/composer/dock/index.native.tsx

@@ -1,5 +1,6 @@
 import { ComposerDockBackground } from "./internal/background";
 export { ComposerDockBackground } from "./internal/background";
+export { ComposerFullscreenBody, ComposerFullscreenFooter } from "./internal/fullscreen";
 import { ScrollView } from "@/components/ui/scroll-view";
 import { useSafeAreaInsets } from "react-native-safe-area-context";
 import { useIsCompactFormFactor } from "@/constants/layout";
@@ -8,22 +9,22 @@ import { resolveContentMaxWidth, useAppSettings } from "@/hooks/use-settings";
 import { KeyboardTranslateView } from "@/keyboard/shift";
 import { createContext, useCallback, useContext, useState, type ReactNode } from "react";
 import { View, type LayoutChangeEvent, type ViewProps, StyleSheet } from "react-native";
+import { StyleSheet as ThemedStyleSheet } from "react-native-unistyles";
 import Animated, {
   useAnimatedStyle,
   useSharedValue,
-  useDerivedValue,
   useAnimatedReaction,
   type SharedValue,
 } from "react-native-reanimated";
 import { useKeyboardShift } from "@/keyboard/shift";
 import {
   resolveCenteredClearance,
-  resolveInlineComposerCapacity,
+  resolveComposerSlotCapacity,
   updateComposerCapacity,
   type ComposerCapacity,
 } from "./internal/capacity";
 
-const ViewportCapacity = createContext<SharedValue<number | undefined> | null>(null);
+const ViewportSizing = createContext<SharedValue<ComposerCapacity | undefined> | null>(null);
 
 interface ComposerViewportProps extends ViewProps {
   bottomInset?: number;
@@ -55,7 +56,6 @@ function ComposerViewport({
     },
     [],
   );
-  const capacity = useDerivedValue(() => sizing.value?.capacity);
   const measureViewport = useCallback(
     (event: LayoutChangeEvent) => {
       measuredHeight.value = event.nativeEvent.layout.height;
@@ -66,20 +66,24 @@ function ComposerViewport({
 
   return (
     <View testID="composer-viewport" {...props} onLayout={measureViewport} collapsable={false}>
-      <ViewportCapacity.Provider value={capacity}>{children}</ViewportCapacity.Provider>
+      <ViewportSizing.Provider value={sizing}>{children}</ViewportSizing.Provider>
     </View>
   );
 }
 
 /** Bound the complete composer (including its controls), not just the text input. */
-function ComposerViewportContent({ style, ...props }: ViewProps) {
+function ComposerViewportContent({
+  style,
+  fullscreen = false,
+  ...props
+}: ViewProps & { fullscreen?: boolean }) {
   const compact = useIsCompactFormFactor();
-  const capacity = useContext(ViewportCapacity);
-  if (!capacity) throw new Error("ComposerViewportContent requires ComposerViewport");
+  const sizing = useContext(ViewportSizing);
+  if (!sizing) throw new Error("ComposerViewportContent requires ComposerViewport");
   const constraint = useAnimatedStyle(() => ({
     // Only viewport changes and keyboard start/end events trigger layout. Motion
     // stays in KeyboardTranslateView and never changes this constraint per frame.
-    maxHeight: resolveInlineComposerCapacity(capacity.value, compact),
+    maxHeight: resolveComposerSlotCapacity(sizing.value, { compact, fullscreen }),
   }));
 
   return (
@@ -108,37 +112,71 @@ function useCenteredClearance(safeAreaBottom: number) {
 interface ComposerDockProps {
   children: [ReactNode, ReactNode, ReactNode?];
   centered?: boolean;
+  /**
+   * Fullscreen is a layout mode of the same mounted composer: the slot fills the
+   * stationary viewport over the content and lays out the keyboard itself, so the
+   * surface stops translating. The screen that owns the chrome hides it.
+   */
+  fullscreen?: boolean;
 }
 
 /** The stationary viewport, translated surface, and bounded composer are one owner. */
 export function ComposerDock({
   children: [content, composer, overlay],
   centered = false,
+  fullscreen = false,
 }: ComposerDockProps) {
   const insets = useSafeAreaInsets();
   const contentMaxWidth = resolveContentMaxWidth(useAppSettings().settings);
   const centeredClearance = useCenteredClearance(insets.bottom);
   // Preserve the existing centered form's visual balance on tablets.
-  const bottomInset = centered ? HEADER_INNER_HEIGHT + 24 : 0;
+  const bottomInset = centered && !fullscreen ? HEADER_INNER_HEIGHT + 24 : 0;
+  const fullscreenSurface = [
+    themedStyles.fullscreenComposer,
+    {
+      paddingTop: insets.top,
+      paddingBottom: insets.bottom,
+      paddingLeft: insets.left,
+      paddingRight: insets.right,
+    },
+  ];
   if (centered) {
+    // Same tree in both modes. Fullscreen stops centering and translating, hides the
+    // setup fields, and lets the composer slot take the whole stationary viewport.
     return (
       <ComposerViewport
-        style={[dockStyles.centeredViewport, { paddingBottom: bottomInset }]}
+        style={
+          fullscreen
+            ? dockStyles.viewport
+            : [dockStyles.centeredViewport, { paddingBottom: bottomInset }]
+        }
         bottomInset={bottomInset}
         centered
         onLayout={centeredClearance.measureViewport}
       >
         <KeyboardTranslateView
-          style={[dockStyles.centered, { maxWidth: contentMaxWidth }]}
+          style={
+            fullscreen ? dockStyles.surface : [dockStyles.centered, { maxWidth: contentMaxWidth }]
+          }
+          enabled={!fullscreen}
           bottomClearance={centeredClearance.value}
           onLayout={centeredClearance.measureForm}
         >
-          <ComposerViewportContent style={dockStyles.composer}>
-            <ScrollView style={dockStyles.setup} keyboardShouldPersistTaps="handled">
+          <ComposerViewportContent
+            style={fullscreen ? dockStyles.surface : dockStyles.composer}
+            fullscreen={fullscreen}
+          >
+            <ScrollView
+              style={fullscreen ? dockStyles.hiddenSetup : dockStyles.setup}
+              keyboardShouldPersistTaps="handled"
+            >
               {content}
             </ScrollView>
-            <ComposerViewportContent style={dockStyles.centeredComposer}>
-              {composer}
+            <ComposerViewportContent
+              style={fullscreen ? dockStyles.surface : dockStyles.centeredComposer}
+              fullscreen={fullscreen}
+            >
+              <View style={fullscreen ? fullscreenSurface : dockStyles.composer}>{composer}</View>
             </ComposerViewportContent>
           </ComposerViewportContent>
           {overlay}
@@ -148,7 +186,7 @@ export function ComposerDock({
   }
   return (
     <ComposerViewport style={dockStyles.viewport}>
-      <KeyboardTranslateView style={dockStyles.surface}>
+      <KeyboardTranslateView style={dockStyles.surface} enabled={!fullscreen}>
         <View
           testID="composer-dock-content"
           collapsable={false}
@@ -162,8 +200,19 @@ export function ComposerDock({
             {content}
           </View>
         </View>
-        <ComposerViewportContent style={dockStyles.composer}>
-          <View style={[dockStyles.composer, { paddingBottom: insets.bottom }]}>{composer}</View>
+        <ComposerViewportContent
+          style={fullscreen ? dockStyles.fullscreenSlot : dockStyles.composer}
+          fullscreen={fullscreen}
+        >
+          <View
+            style={
+              fullscreen
+                ? fullscreenSurface
+                : [dockStyles.composer, { paddingBottom: insets.bottom }]
+            }
+          >
+            {composer}
+          </View>
         </ComposerViewportContent>
         {overlay}
       </KeyboardTranslateView>
@@ -178,9 +227,16 @@ const dockStyles = StyleSheet.create({
   surface: { flex: 1 },
   content: { flex: 1, justifyContent: "flex-end" },
   composer: { width: "100%", flexShrink: 1 },
+  fullscreenSlot: { position: "absolute", top: 0, left: 0, right: 0, bottom: 0 },
   centeredViewport: { flex: 1, alignItems: "center", justifyContent: "center" },
   centered: { flexShrink: 1, width: "100%" },
   // Reserve the composer's own capped height before the setup scroll view shrinks.
   centeredComposer: { width: "100%", flexShrink: 0 },
   setup: { flexGrow: 0, flexShrink: 1, minHeight: 0 },
+  hiddenSetup: { display: "none" },
 });
+
+// The fullscreen composer paints its own surface, including under the safe areas.
+const themedStyles = ThemedStyleSheet.create((theme) => ({
+  fullscreenComposer: { flex: 1, backgroundColor: theme.colors.surface1 },
+}));

packages/app/src/composer/dock/index.tsx

@@ -1,48 +1,69 @@
 export { ComposerDockBackground } from "./internal/background";
+export { ComposerFullscreenBody, ComposerFullscreenFooter } from "./internal/fullscreen";
 import { ScrollView } from "@/components/ui/scroll-view";
-import { useState, useCallback, useMemo, type ReactNode } from "react";
+import { useState, useCallback, useMemo, useRef, type ReactNode } from "react";
 import { View } from "react-native";
 import { StyleSheet } from "react-native-unistyles";
 import { resolveInlineComposerCapacity } from "./internal/capacity";
+import { useFullscreenSlotFrame } from "./internal/fullscreen";
 import { useIsCompactFormFactor } from "@/constants/layout";
 import { HEADER_INNER_HEIGHT } from "@/constants/layout";
 
 interface ComposerDockProps {
   children: [ReactNode, ReactNode, ReactNode?];
   centered?: boolean;
+  /** See the native dock: the same mounted composer fills the visible surface. */
+  fullscreen?: boolean;
 }
 
 export function ComposerDock({
   children: [content, composer, overlay],
   centered = false,
+  fullscreen = false,
 }: ComposerDockProps) {
   const compact = useIsCompactFormFactor();
-  const [availableHeight, setAvailableHeight] = useState<number>();
+  const [surfaceSize, setSurfaceSize] = useState<{ width: number; height: number }>();
+  const surfaceRef = useRef<View>(null);
+  const fullscreenFrame = useFullscreenSlotFrame(fullscreen, surfaceRef, surfaceSize);
   const constraint = useMemo(
-    () => ({ maxHeight: resolveInlineComposerCapacity(availableHeight, compact) }),
-    [availableHeight, compact],
+    () => ({ maxHeight: resolveInlineComposerCapacity(surfaceSize?.height, compact) }),
+    [surfaceSize?.height, compact],
   );
   const measureViewport = useCallback((event: import("react-native").LayoutChangeEvent) => {
-    const { height } = event.nativeEvent.layout;
-    if (height > 0) setAvailableHeight(height);
+    const { width, height } = event.nativeEvent.layout;
+    if (height > 0) setSurfaceSize({ width, height });
   }, []);
   if (centered) {
     return (
-      <View style={styles.centered} onLayout={measureViewport}>
+      <View ref={surfaceRef} style={styles.centered} onLayout={measureViewport}>
         <View style={styles.form}>
           <ScrollView style={styles.setup} keyboardShouldPersistTaps="handled">
             {content}
           </ScrollView>
-          <View style={[styles.centeredComposer, constraint]}>{composer}</View>
+          <View
+            style={
+              fullscreen
+                ? [styles.fullscreenComposer, fullscreenFrame]
+                : [styles.centeredComposer, constraint]
+            }
+          >
+            {composer}
+          </View>
           {overlay}
         </View>
       </View>
     );
   }
   return (
-    <View style={styles.surface} onLayout={measureViewport}>
+    <View ref={surfaceRef} style={styles.surface} onLayout={measureViewport}>
       <View style={styles.content}>{content}</View>
-      <View style={[styles.composer, constraint]}>{composer}</View>
+      <View
+        style={
+          fullscreen ? [styles.fullscreenComposer, fullscreenFrame] : [styles.composer, constraint]
+        }
+      >
+        {composer}
+      </View>
       {overlay}
     </View>
   );
@@ -52,6 +73,10 @@ const styles = StyleSheet.create((theme) => ({
   surface: { flex: 1, overflow: "hidden" },
   content: { flex: 1, justifyContent: "flex-end" },
   composer: { width: "100%", flexShrink: 1 },
+  // Fixed, not absolute: a touch pan that starts inside an overflow-hidden ancestor
+  // never reaches the zoomed visual viewport, while a fixed box chains to the viewport
+  // directly. React Native Web renders `fixed`; React Native's style type omits it.
+  fullscreenComposer: { position: "fixed" as "absolute" },
   centered: {
     flex: 1,
     alignItems: "center",

packages/app/src/composer/dock/internal/capacity.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, it } from "vitest";
 import {
   resolveCenteredClearance,
+  resolveComposerSlotCapacity,
   resolveInlineComposerCapacity,
   resolveComposerCapacity,
   updateComposerCapacity,
@@ -19,6 +20,20 @@ describe("composer viewport", () => {
     expect(resolveInlineComposerCapacity(open.capacity, false)).toBe(245);
     expect(resolveInlineComposerCapacity(undefined, true)).toBeUndefined();
   });
+  it("lets a fullscreen composer fill the viewport while inline keeps its cap", () => {
+    const open = updateComposerCapacity(undefined, {
+      height: 582,
+      bottomInset: 24,
+      safeAreaBottom: 0,
+      centered: false,
+      keyboardShift: 308,
+    });
+    expect(resolveComposerSlotCapacity(open, { compact: true, fullscreen: true })).toBe(582);
+    expect(resolveComposerSlotCapacity(open, { compact: true, fullscreen: false })).toBe(147);
+    expect(resolveComposerSlotCapacity(undefined, { compact: true, fullscreen: true })).toBe(
+      undefined,
+    );
+  });
   it("preserves the editing capacity when the keyboard closes", () => {
     const viewport = { height: 582, bottomInset: 24, safeAreaBottom: 0, centered: false };
     const open = updateComposerCapacity(undefined, { ...viewport, keyboardShift: 308 });

packages/app/src/composer/dock/internal/capacity.ts

@@ -10,6 +10,8 @@ interface ComposerGeometry {
 export interface ComposerCapacity {
   keyboardReserve: number;
   capacity: number;
+  /** The stationary viewport; a fullscreen composer fills it and lays out the keyboard itself. */
+  viewportHeight: number;
 }
 
 export function resolveComposerCapacity(input: ComposerGeometry): number {
@@ -48,6 +50,7 @@ export function updateComposerCapacity(
   return {
     keyboardReserve,
     capacity: resolveComposerCapacity({ ...input, keyboardShift: keyboardReserve }),
+    viewportHeight: input.height,
   };
 }
 
@@ -60,3 +63,19 @@ export function resolveInlineComposerCapacity(
   if (capacity === undefined) return undefined;
   return compact ? capacity * 0.6 : capacity;
 }
+
+export interface ComposerSlotLayout {
+  compact: boolean;
+  fullscreen: boolean;
+}
+
+/** The bound on the composer slot: inline capacity, or the whole viewport in fullscreen. */
+export function resolveComposerSlotCapacity(
+  sizing: ComposerCapacity | undefined,
+  layout: ComposerSlotLayout,
+): number | undefined {
+  "worklet";
+  if (sizing === undefined) return undefined;
+  if (layout.fullscreen) return sizing.viewportHeight;
+  return resolveInlineComposerCapacity(sizing.capacity, layout.compact);
+}

packages/app/src/composer/dock/internal/fullscreen.native.tsx

@@ -0,0 +1,39 @@
+import type { ReactNode } from "react";
+import { StyleSheet, type ViewProps } from "react-native";
+import Animated, { useAnimatedStyle } from "react-native-reanimated";
+import { KeyboardTranslateView, useKeyboardShift } from "@/keyboard/shift";
+
+/**
+ * The editing region of a composer. Inline it only continues the shrink chain. In
+ * fullscreen it fills the stationary frame and reserves the keyboard's space at
+ * motion boundaries, the same boundary-time layout the dock capacity uses: the
+ * keyboard start/end events write `layoutShift`; frames in between move the footer.
+ */
+export function ComposerFullscreenBody({
+  fullscreen,
+  children,
+}: {
+  fullscreen: boolean;
+  children: ReactNode;
+}) {
+  const { layoutShift } = useKeyboardShift();
+  const reservation = useAnimatedStyle(() => ({
+    marginBottom: fullscreen ? layoutShift.value : 0,
+  }));
+  return (
+    <Animated.View style={[fullscreen ? styles.fullscreen : styles.inline, reservation]}>
+      {children}
+    </Animated.View>
+  );
+}
+
+/** The Send row of a fullscreen composer rides the keyboard like the inline dock surface. */
+export function ComposerFullscreenFooter({ children, ...props }: ViewProps) {
+  return <KeyboardTranslateView {...props}>{children}</KeyboardTranslateView>;
+}
+
+// Plain React Native styles: these land on Reanimated views (docs/unistyles.md).
+const styles = StyleSheet.create({
+  inline: { flexShrink: 1 },
+  fullscreen: { flex: 1, minHeight: 0 },
+});

packages/app/src/composer/dock/internal/fullscreen.tsx

@@ -0,0 +1,89 @@
+import { useLayoutEffect, useState, type ReactNode, type RefObject } from "react";
+import { StyleSheet, View, type ViewProps } from "react-native";
+
+/** The editing region of a composer; see the native file for the keyboard contract. */
+export function ComposerFullscreenBody({
+  fullscreen,
+  children,
+}: {
+  fullscreen: boolean;
+  children: ReactNode;
+}) {
+  return <View style={fullscreen ? styles.fullscreen : styles.inline}>{children}</View>;
+}
+
+export function ComposerFullscreenFooter({ children, ...props }: ViewProps) {
+  return <View {...props}>{children}</View>;
+}
+
+export interface ComposerSlotFrame {
+  top: number;
+  left: number;
+  width: number;
+  height: number;
+}
+
+/**
+ * Where a fullscreen composer sits, in layout-viewport coordinates for a fixed box: the
+ * part of the dock surface the browser's visible viewport shows. A mobile browser
+ * keyboard shrinks or pans that viewport without resizing the page, so the frame
+ * follows it instead of the layout.
+ */
+export function useFullscreenSlotFrame(
+  active: boolean,
+  surfaceRef: RefObject<View | null>,
+  surfaceSize: { width: number; height: number } | undefined,
+): ComposerSlotFrame | undefined {
+  const [frame, setFrame] = useState<ComposerSlotFrame>();
+  useLayoutEffect(() => {
+    if (!active) {
+      setFrame(undefined);
+      return;
+    }
+    const update = () => {
+      const surface = surfaceRef.current as unknown as HTMLElement | null;
+      if (!surface) return;
+      setFrame(resolveVisibleSurfaceFrame(surface.getBoundingClientRect(), readVisibleViewport()));
+    };
+    const visualViewport = window.visualViewport;
+    update();
+    visualViewport?.addEventListener("resize", update);
+    visualViewport?.addEventListener("scroll", update);
+    window.addEventListener("resize", update);
+    return () => {
+      visualViewport?.removeEventListener("resize", update);
+      visualViewport?.removeEventListener("scroll", update);
+      window.removeEventListener("resize", update);
+    };
+  }, [active, surfaceRef, surfaceSize]);
+  return frame;
+}
+
+function readVisibleViewport() {
+  const viewport = window.visualViewport;
+  return {
+    top: viewport?.offsetTop ?? 0,
+    left: viewport?.offsetLeft ?? 0,
+    width: viewport?.width ?? window.innerWidth,
+    height: viewport?.height ?? window.innerHeight,
+  };
+}
+
+function resolveVisibleSurfaceFrame(
+  surface: { top: number; left: number; right: number; bottom: number },
+  viewport: { top: number; left: number; width: number; height: number },
+): ComposerSlotFrame {
+  const top = Math.max(viewport.top, surface.top);
+  const left = Math.max(viewport.left, surface.left);
+  return {
+    top,
+    left,
+    width: Math.max(0, Math.min(viewport.left + viewport.width, surface.right) - left),
+    height: Math.max(0, Math.min(viewport.top + viewport.height, surface.bottom) - top),
+  };
+}
+
+const styles = StyleSheet.create({
+  inline: { flexShrink: 1 },
+  fullscreen: { flex: 1, minHeight: 0 },
+});

packages/app/src/composer/draft/input-draft.live.test.tsx

@@ -210,6 +210,8 @@ describe("useAgentInputDraft live contract", () => {
     });
 
     const hydratedTextReplacement = getLatest().textReplacement;
+    // The editor applies a retained caret to the hydrated text, so hydration announces itself.
+    expect(hydratedTextReplacement.kind).toBe("hydrated");
 
     await act(async () => {
       getLatest().editText("hello world");
@@ -223,6 +225,7 @@ describe("useAgentInputDraft live contract", () => {
     });
 
     expect(getLatest().textReplacement).not.toBe(hydratedTextReplacement);
+    expect(getLatest().textReplacement.kind).toBe("replace");
     expect(getLatest().textReplacement.text).toBe("replacement text");
 
     await act(async () => {

packages/app/src/composer/draft/input-draft.ts

@@ -17,6 +17,7 @@ import {
 } from "@/composer/draft/input-draft-core";
 import {
   buildDraftCommandTarget,
+  resolveEffectiveComposerModeId,
   resolveEffectiveComposerModelId,
   resolveEffectiveComposerThinkingOptionId,
   type ProviderSelectionState,
@@ -46,6 +47,7 @@ interface UseAgentInputDraftInput {
 
 type DraftComposerState = UseAgentFormStateResult & {
   workingDir: string;
+  effectiveModeId: string;
   effectiveModelId: string;
   effectiveThinkingOptionId: string;
   featureValues: Record<string, unknown> | undefined;
@@ -121,10 +123,10 @@ export function useAgentInputDraft(input: UseAgentInputDraftInput): AgentInputDr
   }));
 
   const publishTextReplacement = useCallback(
-    (nextText: string) => {
+    (kind: "hydrated" | "replace", nextText: string) => {
       textReplacementRevisionRef.current += 1;
       setTextReplacement({
-        kind: "replace",
+        kind,
         key: `${draftKey}:${textReplacementRevisionRef.current}`,
         text: nextText,
       });
@@ -174,7 +176,7 @@ export function useAgentInputDraft(input: UseAgentInputDraftInput): AgentInputDr
     (nextText: string) => {
       textPublication.cancel();
       useDraftStore.getState().editDraftText({ draftKey, text: nextText });
-      publishTextReplacement(nextText);
+      publishTextReplacement("replace", nextText);
     },
     [draftKey, publishTextReplacement, textPublication],
   );
@@ -227,7 +229,7 @@ export function useAgentInputDraft(input: UseAgentInputDraftInput): AgentInputDr
       await useDraftStore.getState().hydrateDraftInput({ draftKey });
       if (!cancelled) {
         const hydratedText = useDraftStore.getState().getDraftInput(draftKey)?.text ?? "";
-        publishTextReplacement(hydratedText);
+        publishTextReplacement("hydrated", hydratedText);
         setHydratedDraftKey(draftKey);
       }
     })();
@@ -256,6 +258,11 @@ export function useAgentInputDraft(input: UseAgentInputDraftInput): AgentInputDr
     ],
   );
 
+  const effectiveModeId = useMemo(
+    () => resolveEffectiveComposerModeId(providerSelection, formState.isModelLoading),
+    [formState.isModelLoading, providerSelection],
+  );
+
   const effectiveModelId = useMemo(
     () => resolveEffectiveComposerModelId(providerSelection),
     [providerSelection],
@@ -315,6 +322,7 @@ export function useAgentInputDraft(input: UseAgentInputDraftInput): AgentInputDr
     return {
       ...formState,
       workingDir,
+      effectiveModeId,
       effectiveModelId,
       effectiveThinkingOptionId,
       featureValues: draftFeatureValues,
@@ -329,6 +337,7 @@ export function useAgentInputDraft(input: UseAgentInputDraftInput): AgentInputDr
   }, [
     commandDraft,
     composerOptions,
+    effectiveModeId,
     effectiveModelId,
     effectiveThinkingOptionId,
     draftFeatures,
@@ -355,6 +364,7 @@ export function useAgentInputDraft(input: UseAgentInputDraftInput): AgentInputDr
 
 export const __private__ = {
   resolveDraftKey,
+  resolveEffectiveComposerModeId,
   resolveEffectiveComposerModelId,
   resolveEffectiveComposerThinkingOptionId,
   buildDraftCommandTarget,

packages/app/src/composer/draft/workspace-tab.tsx

@@ -6,6 +6,7 @@ import { ComposerDock } from "@/composer/dock";
 import { useContainerWidthBelow } from "@/hooks/use-container-width";
 import invariant from "tiny-invariant";
 import { Composer } from "@/composer";
+import { useComposerEditingSession, useComposerFullscreen } from "@/composer/editing-session";
 import { FileDropZone } from "@/components/file-drop/file-drop-zone";
 import { ComposerImportPill } from "@/composer/draft/import-pill";
 import { COMPOSER_PILL_CLEARANCE } from "@/composer/pill-styles";
@@ -86,46 +87,30 @@ function resolveAutoSubmitConfig(
   };
 }
 
-// Reconcile the form's selected mode against the currently discovered modes.
-// The mode picker displays modeOptions[0] when the stored mode isn't in the
-// list (e.g. a globally-remembered "plan" that this workspace's OpenCode config
-// no longer defines), so the submitted mode must match that display — otherwise
-// we'd send a stale mode the provider rejects while the UI showed a valid one.
-function reconcileSelectedMode(modeOptionIds: readonly string[], selectedMode: string): string {
-  if (modeOptionIds.length === 0) {
-    return "";
-  }
-  return modeOptionIds.includes(selectedMode) ? selectedMode : (modeOptionIds[0] ?? "");
-}
-
 function resolveDraftModeIdOverride(input: {
   autoSubmitConfig: AutoSubmitConfig | null;
-  modeOptionIds: readonly string[];
-  selectedMode: string;
+  effectiveModeId: string;
 }): { modeId: string } | Record<string, never> {
-  const { autoSubmitConfig, modeOptionIds, selectedMode } = input;
+  const { autoSubmitConfig, effectiveModeId } = input;
   if (autoSubmitConfig?.modeId) {
     return { modeId: autoSubmitConfig.modeId };
   }
-  const reconciled = reconcileSelectedMode(modeOptionIds, selectedMode);
-  if (reconciled !== "") {
-    return { modeId: reconciled };
+  if (effectiveModeId !== "") {
+    return { modeId: effectiveModeId };
   }
   return {};
 }
 
 function resolveDraftModeId(input: {
   autoSubmitConfig: AutoSubmitConfig | null;
-  modeOptionIds: readonly string[];
-  selectedMode: string;
+  effectiveModeId: string;
 }): string | null {
-  const { autoSubmitConfig, modeOptionIds, selectedMode } = input;
+  const { autoSubmitConfig, effectiveModeId } = input;
   if (autoSubmitConfig?.modeId !== undefined) {
     return autoSubmitConfig.modeId;
   }
-  const reconciled = reconcileSelectedMode(modeOptionIds, selectedMode);
-  if (reconciled !== "") {
-    return reconciled;
+  if (effectiveModeId !== "") {
+    return effectiveModeId;
   }
   return null;
 }
@@ -143,8 +128,7 @@ async function submitDraftCreateRequest(input: {
   autoSubmitConfig: AutoSubmitConfig | null;
   composerState: {
     selectedProvider: string | null;
-    selectedMode: string;
-    modeOptions: readonly { id: string }[];
+    effectiveModeId: string;
     effectiveModelId: string | null;
     effectiveThinkingOptionId: string | null;
     featureValues: Record<string, unknown> | undefined;
@@ -177,8 +161,7 @@ async function submitDraftCreateRequest(input: {
   }
   const modeIdOverride = resolveDraftModeIdOverride({
     autoSubmitConfig,
-    modeOptionIds: composerState.modeOptions.map((mode) => mode.id),
-    selectedMode: composerState.selectedMode,
+    effectiveModeId: composerState.effectiveModeId,
   });
   const config = buildWorkspaceDraftAgentConfig({
     provider,
@@ -219,8 +202,7 @@ function buildDraftAgentSnapshot(input: {
   composerState: {
     effectiveModelId: string | null;
     effectiveThinkingOptionId: string | null;
-    modeOptions: readonly { id: string }[];
-    selectedMode: string;
+    effectiveModeId: string;
     selectedProvider: string | null;
     agentControls: { features?: Agent["features"] };
   };
@@ -234,8 +216,7 @@ function buildDraftAgentSnapshot(input: {
     autoSubmitConfig?.thinkingOptionId ?? (composerState.effectiveThinkingOptionId || null);
   const modeId = resolveDraftModeId({
     autoSubmitConfig,
-    modeOptionIds: composerState.modeOptions.map((mode) => mode.id),
-    selectedMode: composerState.selectedMode,
+    effectiveModeId: composerState.effectiveModeId,
   });
   const provider = autoSubmitConfig?.provider ?? composerState.selectedProvider;
   if (!provider) {
@@ -405,6 +386,8 @@ export function WorkspaceDraftAgentTab({
   }, [pendingCreateAttempt]);
   const allowsEmptyAutoSubmit = pendingAutoSubmit?.allowEmptyText === true;
   const isCompactFormFactor = useIsCompactFormFactor();
+  const editingSession = useComposerEditingSession("chat");
+  const isComposerFullscreen = useComposerFullscreen(editingSession);
   const { onLayout: onInputAreaLayout, isBelow: isCompactComposerLayout } = useContainerWidthBelow(
     COMPACT_FORM_FACTOR_WIDTH,
     { initialIsBelow: isCompactFormFactor },
@@ -648,10 +631,10 @@ export function WorkspaceDraftAgentTab({
 
   return (
     <FileDropZone style={styles.container}>
-      <ComposerDock>
+      <ComposerDock fullscreen={isComposerFullscreen}>
         {dockContent}
         <View style={animatedStaticStyles.inputAreaWrapper} onLayout={onInputAreaLayout}>
-          {importPillPress ? (
+          {importPillPress && !isComposerFullscreen ? (
             <View style={styles.importPillRow}>
               <View style={styles.importPillContent}>
                 <ComposerImportPill onPress={importPillPress} />
@@ -675,6 +658,7 @@ export function WorkspaceDraftAgentTab({
             onChangeAttachments={draftInput.setAttachments}
             cwd={composerState.workingDir}
             clearDraft={draftInput.clear}
+            editingSession={editingSession}
             autoFocus={shouldAutoFocusWorkspaceDraftComposer({ isPaneFocused, isSubmitting })}
             autoFocusKey={String(draftInput.attachmentFocusRequestId)}
             onFocusInput={handleFocusInputCallback}
@@ -692,6 +676,8 @@ const animatedStaticStyles = RNStyleSheet.create({
   inputAreaWrapper: {
     width: "100%",
     flexShrink: 1,
+    // Content-sized inline; fills the dock's fullscreen slot.
+    flexGrow: 1,
   },
 });
 

packages/app/src/composer/editing-session/index.test.ts

@@ -1,52 +1,61 @@
 import { describe, expect, it } from "vitest";
-import { ComposerEditingSession } from "./index";
+import { ComposerEditingSession, ComposerEditingSessions } from "./index";
 
-function leaveLiveDraft(session: ComposerEditingSession) {
-  session.captureForRemount({
-    snapshot: { text: "Unpublished live draft", selection: { start: 4, end: 17 } },
-    focused: true,
-    replacementKey: "draft:applied",
-  });
-}
-
-describe("composer editing remount handoff", () => {
-  it("keeps live text and selection when remounting from an initial draft publication", () => {
+describe("composer editing session", () => {
+  it("publishes fullscreen changes once per transition", () => {
     const session = new ComposerEditingSession();
-    leaveLiveDraft(session);
-    const handoff = session.takeHandoff({ kind: "initial", key: "draft:initial", text: "stale" });
-    expect(handoff?.snapshot).toEqual({
-      text: "Unpublished live draft",
-      selection: { start: 4, end: 17 },
-    });
-    expect(handoff?.focused).toBe(true);
+    const changes: boolean[] = [];
+    session.subscribe(() => changes.push(session.getFullscreen()));
+    session.setFullscreen(true);
+    session.setFullscreen(true);
+    session.setFullscreen(false);
+    expect(changes).toEqual([true, false]);
   });
 
-  it("keeps local edits when the last applied replacement is still current", () => {
+  it("hands the retained caret and focus intent to exactly one later mount", () => {
     const session = new ComposerEditingSession();
-    leaveLiveDraft(session);
-    const handoff = session.takeHandoff({
-      kind: "replace",
-      key: "draft:applied",
-      text: "old replacement",
-    });
-    expect(handoff?.snapshot).toEqual({
-      text: "Unpublished live draft",
-      selection: { start: 4, end: 17 },
-    });
+    expect(session.takeEditor()).toBeNull();
+    session.retainEditor({ selection: { start: 4, end: 17 }, focused: true });
+    expect(session.takeEditor()).toEqual({ selection: { start: 4, end: 17 }, focused: true });
+    expect(session.takeEditor()).toBeNull();
+  });
+});
+
+describe("composer editing sessions", () => {
+  const workspace = "server:workspace";
+  const target = JSON.stringify({ kind: "agent", agentId: "a" });
+
+  it("keeps one session per tab and purpose until the tab target changes", () => {
+    const sessions = new ComposerEditingSessions();
+    const chat = sessions.get(workspace, "tab-1", target, "chat");
+    expect(sessions.get(workspace, "tab-1", target, "chat")).toBe(chat);
+    expect(sessions.get(workspace, "tab-1", target, "terminal")).not.toBe(chat);
+    const retargeted = JSON.stringify({ kind: "agent", agentId: "b" });
+    expect(sessions.get(workspace, "tab-1", retargeted, "chat")).not.toBe(chat);
+  });
+
+  it("reports a tab as fullscreen while any of its composers is fullscreen", () => {
+    const sessions = new ComposerEditingSessions();
+    const notifications: boolean[] = [];
+    sessions.subscribe(() => notifications.push(sessions.isTabFullscreen(workspace, "tab-1")));
+    const chat = sessions.get(workspace, "tab-1", target, "chat");
+    sessions.get(workspace, "tab-2", target, "chat").setFullscreen(true);
+    expect(sessions.isTabFullscreen(workspace, "tab-1")).toBe(false);
+    expect(sessions.isTabFullscreen(workspace, null)).toBe(false);
+    chat.setFullscreen(true);
+    expect(sessions.isTabFullscreen(workspace, "tab-1")).toBe(true);
+    chat.setFullscreen(false);
+    expect(notifications).toEqual([false, true, false]);
+  });
+
+  it("drops sessions for closed tabs and keeps retained ones", () => {
+    const sessions = new ComposerEditingSessions();
+    const kept = sessions.get(workspace, "tab-1", target, "chat");
+    kept.setFullscreen(true);
+    sessions.get(workspace, "tab-2", target, "chat").setFullscreen(true);
+    sessions.retain(workspace, ["tab-1"]);
+    expect(sessions.get(workspace, "tab-1", target, "chat")).toBe(kept);
+    expect(sessions.isTabFullscreen(workspace, "tab-2")).toBe(false);
+    expect(sessions.get(workspace, "tab-2", target, "chat").getFullscreen()).toBe(false);
   });
-
-  it.each(["New explicit draft", ""])(
-    "honors an explicit replacement made while the editor is absent: %j",
-    (text) => {
-      const session = new ComposerEditingSession();
-      leaveLiveDraft(session);
-      const handoff = session.takeHandoff({ kind: "replace", key: "draft:new", text });
-      expect(handoff?.snapshot).toEqual({
-        text,
-        selection: { start: text.length, end: text.length },
-      });
-      expect(handoff?.focused).toBe(true);
-      expect(session.takeHandoff({ kind: "replace", key: "draft:new", text })).toBeNull();
-    },
-  );
 });

packages/app/src/composer/editing-session/index.tsx

@@ -1,5 +1,6 @@
 import React, {
   createContext,
+  useCallback,
   useContext,
   useEffect,
   useMemo,
@@ -7,62 +8,72 @@ import React, {
   useSyncExternalStore,
   type ReactNode,
 } from "react";
-import type { TextReplacement } from "@/composer/types";
 import type { ComposerInputMode } from "@/composer/input-mode";
 
-export interface ComposerEditingHandoff {
-  snapshot: { text: string; selection: { start: number; end: number } };
-  focused: boolean;
-  replacementKey: string;
+export interface ComposerSelection {
+  start: number;
+  end: number;
 }
 
-/** Editing metadata outlives a layout's input; draft text still belongs to its draft owner. */
+/** What an unmounting editor leaves for the next mount of the same session. */
+export interface ComposerRetainedEditor {
+  selection: ComposerSelection;
+  /** The editor was focused, or meant to regain focus once its pane became active. */
+  focused: boolean;
+}
+
+/**
+ * Editing state that outlives the editor's mount. Draft text belongs to its draft
+ * owner; the editor keeps its own live buffer across layout modes. Switching between
+ * the compact and desktop screens remounts the editor, so the session carries the
+ * caret and focus intent across that remount while the draft owner carries the text.
+ */
 export class ComposerEditingSession {
   private fullscreen = false;
-  private handoff: ComposerEditingHandoff | null = null;
+  private retained: ComposerRetainedEditor | null = null;
   private listeners = new Set<() => void>();
+  constructor(private readonly onChange?: () => void) {}
   getFullscreen = () => this.fullscreen;
+  /** Called by the unmounting editor; the next mount of this session takes it. */
+  retainEditor(retained: ComposerRetainedEditor) {
+    this.retained = retained;
+  }
+  takeEditor(): ComposerRetainedEditor | null {
+    const retained = this.retained;
+    this.retained = null;
+    return retained;
+  }
   subscribe = (listener: () => void) => {
     this.listeners.add(listener);
     return () => {
       this.listeners.delete(listener);
     };
   };
-  changePresentation(fullscreen: boolean, handoff: ComposerEditingHandoff) {
-    this.captureForRemount(handoff);
+  setFullscreen(fullscreen: boolean) {
     if (fullscreen === this.fullscreen) return;
     this.fullscreen = fullscreen;
     for (const listener of this.listeners) listener();
-  }
-  captureForRemount(handoff: ComposerEditingHandoff) {
-    this.handoff = handoff;
-  }
-  peekHandoff(replacement: TextReplacement): ComposerEditingHandoff | null {
-    const handoff = this.handoff;
-    if (!handoff || replacement.kind === "initial" || replacement.key === handoff.replacementKey)
-      return handoff;
-    // A replacement command issued since capture supersedes the old editor's live buffer.
-    return {
-      snapshot: {
-        text: replacement.text,
-        selection: { start: replacement.text.length, end: replacement.text.length },
-      },
-      focused: handoff.focused,
-      replacementKey: replacement.key,
-    };
-  }
-  takeHandoff(replacement: TextReplacement) {
-    const handoff = this.peekHandoff(replacement);
-    this.handoff = null;
-    return handoff;
+    this.onChange?.();
   }
 }
 
-class ComposerEditingSessions {
-  private workspaces = new Map<
-    string,
-    Map<string, { targetKey: string; sessions: Map<ComposerInputMode, ComposerEditingSession> }>
-  >();
+interface TabSessions {
+  targetKey: string;
+  sessions: Map<ComposerInputMode, ComposerEditingSession>;
+}
+
+export class ComposerEditingSessions {
+  private workspaces = new Map<string, Map<string, TabSessions>>();
+  private listeners = new Set<() => void>();
+  private notify = () => {
+    for (const listener of this.listeners) listener();
+  };
+  subscribe = (listener: () => void) => {
+    this.listeners.add(listener);
+    return () => {
+      this.listeners.delete(listener);
+    };
+  };
   get(workspaceKey: string, tabId: string, targetKey: string, purpose: ComposerInputMode) {
     let workspace = this.workspaces.get(workspaceKey);
     if (!workspace) {
@@ -76,17 +87,31 @@ class ComposerEditingSessions {
     }
     let session = tab.sessions.get(purpose);
     if (!session) {
-      session = new ComposerEditingSession();
+      session = new ComposerEditingSession(this.notify);
       tab.sessions.set(purpose, session);
     }
     return session;
   }
+  /** A tab is fullscreen when any of its composers is; the screen hides its chrome for it. */
+  isTabFullscreen(workspaceKey: string, tabId: string | null): boolean {
+    if (tabId === null) return false;
+    const tab = this.workspaces.get(workspaceKey)?.get(tabId);
+    if (!tab) return false;
+    for (const session of tab.sessions.values()) if (session.getFullscreen()) return true;
+    return false;
+  }
   retain(workspaceKey: string, tabIds: readonly string[]) {
     const workspace = this.workspaces.get(workspaceKey);
     if (!workspace) return;
     const retained = new Set(tabIds);
-    for (const tabId of workspace.keys()) if (!retained.has(tabId)) workspace.delete(tabId);
+    let changed = false;
+    for (const tabId of workspace.keys()) {
+      if (retained.has(tabId)) continue;
+      workspace.delete(tabId);
+      changed = true;
+    }
     if (workspace.size === 0) this.workspaces.delete(workspaceKey);
+    if (changed) this.notify();
   }
 }
 
@@ -140,3 +165,16 @@ export function useComposerEditingSession(
 export function useComposerFullscreen(session: ComposerEditingSession): boolean {
   return useSyncExternalStore(session.subscribe, session.getFullscreen, session.getFullscreen);
 }
+/** Whether the composer of a workspace tab is fullscreen, for the chrome that tab sits under. */
+export function useComposerTabFullscreen(workspaceKey: string, tabId: string | null): boolean {
+  const sessions = useContext(SessionsContext);
+  const subscribe = useCallback(
+    (listener: () => void) => sessions?.subscribe(listener) ?? (() => {}),
+    [sessions],
+  );
+  const read = useCallback(
+    () => sessions?.isTabFullscreen(workspaceKey, tabId) ?? false,
+    [sessions, workspaceKey, tabId],
+  );
+  return useSyncExternalStore(subscribe, read, read);
+}

packages/app/src/composer/index.tsx

@@ -1,4 +1,8 @@
-import { useComposerEditingSession, useComposerFullscreen } from "./editing-session";
+import {
+  useComposerEditingSession,
+  useComposerFullscreen,
+  type ComposerEditingSession,
+} from "./editing-session";
 import type { ComposerTextSource } from "./text-source";
 import { createStore, type StoreApi } from "zustand/vanilla";
 import { useStore } from "zustand";
@@ -27,6 +31,7 @@ import {
 import { useTranslation } from "react-i18next";
 import { StyleSheet, withUnistyles } from "react-native-unistyles";
 import { useIsCompactFormFactor } from "@/constants/layout";
+import { usePanelStore } from "@/stores/panel-store";
 import { useHasFinePointer } from "@/hooks/use-fine-pointer";
 import { useShallow } from "zustand/shallow";
 import {
@@ -967,6 +972,12 @@ interface ComposerProps {
   submitLabel?: string;
   /** Overrides the mode's default placeholder, for text only the caller can build. */
   placeholder?: string;
+  /**
+   * The host that also lays out the dock and chrome shares this session so its
+   * fullscreen state and the composer's agree. Defaults to the tab's session for
+   * `inputMode`.
+   */
+  editingSession?: ComposerEditingSession;
 }
 
 const EMPTY_ARRAY: readonly QueuedMessage[] = [];
@@ -1182,8 +1193,14 @@ function ComposerVoiceModeButton({
 }
 
 export function Composer({ isPaneFocused, ...props }: ComposerProps) {
+  // A compact overlay panel (agent list, explorer) covers the pane without taking its
+  // focus. The composer gives up input from the moment the user asks for the panel,
+  // not when its motion settles, so the exit action and autocomplete never race it.
+  const isCompact = useIsCompactFormFactor();
+  const overlayPanelRequested = usePanelStore((state) => state.mobilePanel.target !== "agent");
+  const coveredByOverlayPanel = isCompact && overlayPanelRequested;
   return (
-    <ComposerKeyboardScopeProvider isActiveComposer={isPaneFocused}>
+    <ComposerKeyboardScopeProvider isActiveComposer={isPaneFocused && !coveredByOverlayPanel}>
       <RenderProfile id="ComposerContent">
         <ComposerContent {...props} />
       </RenderProfile>
@@ -1234,6 +1251,7 @@ function ComposerContentImpl({
   inputWrapperStyle,
   isCompactLayout: isCompactLayoutOverride,
   inputMode = "chat",
+  editingSession: providedEditingSession,
   readOnly = false,
   submitLabel,
   placeholder,
@@ -1339,7 +1357,7 @@ function ComposerContentImpl({
   const nextPendingFileId = useRef(0);
   const isUploadingFile = pendingFiles.length > 0;
   const [pendingNativeImagePastes, setPendingNativeImagePastes] = useState(0);
-  const editingSession = useComposerEditingSession(inputMode);
+  const editingSession = useComposerEditingSession(inputMode, providedEditingSession);
   const isFullscreen = useComposerFullscreen(editingSession);
   const [sendError, setSendError] = useState<string | null>(null);
   const [isMessageInputFocused, setIsMessageInputFocused] = useState(false);
@@ -2250,9 +2268,23 @@ function ComposerContentImpl({
     [githubSearchItems, selectedAttachments, handleToggleGithubItem],
   );
 
+  // Fullscreen fills the dock slot: the chain down to the input stretches and drops
+  // the inline padding, which the fullscreen presentation supplies itself.
   const inputAreaContainerStyle = useMemo(
-    () => [styles.inputAreaContainer, isComposerLocked && styles.inputAreaLocked],
-    [isComposerLocked],
+    () => [
+      styles.inputAreaContainer,
+      isComposerLocked && styles.inputAreaLocked,
+      isFullscreen && styles.inputAreaFullscreen,
+    ],
+    [isComposerLocked, isFullscreen],
+  );
+  const inputAreaContentStyle = useMemo(
+    () => [styles.inputAreaContent, isFullscreen && styles.fullscreenFill],
+    [isFullscreen],
+  );
+  const messageInputContainerStyle = useMemo(
+    () => [styles.messageInputContainer, isFullscreen && styles.fullscreenFill],
+    [isFullscreen],
   );
 
   const attachmentTray = useMemo(
@@ -2363,15 +2395,19 @@ function ComposerContentImpl({
         focusMessageInputForKeyboardAction={focusMessageInputForKeyboardAction}
         isMessageInputFocused={isMessageInputFocused}
       />
-      <View style={animatedStaticStyles.container}>
+      <View
+        style={
+          isFullscreen ? animatedStaticStyles.fullscreenContainer : animatedStaticStyles.container
+        }
+      >
         <AttachmentLightbox source={lightboxSource} onClose={handleLightboxClose} />
         {/* Input area */}
         <View style={inputAreaContainerStyle}>
-          <View style={styles.inputAreaContent}>
-            {queueList}
+          <View style={inputAreaContentStyle}>
+            {isFullscreen ? null : queueList}
             {!isFullscreen && sendErrorNode}
 
-            <View ref={messageInputContainerRef} style={styles.messageInputContainer}>
+            <View ref={messageInputContainerRef} style={messageInputContainerStyle}>
               <ComposerAutocompleteBinding
                 text={textSource}
                 cursor={cursor}
@@ -2475,6 +2511,12 @@ const animatedStaticStyles = RNStyleSheet.create({
     flexShrink: 1,
     position: "relative",
   },
+  fullscreenContainer: {
+    flexDirection: "column",
+    flex: 1,
+    minHeight: 0,
+    position: "relative",
+  },
 });
 
 const styles = StyleSheet.create((theme: Theme) => ({
@@ -2496,6 +2538,18 @@ const styles = StyleSheet.create((theme: Theme) => ({
   inputAreaLocked: {
     opacity: 0.6,
   },
+  inputAreaFullscreen: {
+    flex: 1,
+    minHeight: 0,
+    alignItems: "stretch",
+    paddingHorizontal: 0,
+    paddingBottom: 0,
+  },
+  fullscreenFill: {
+    flex: 1,
+    minHeight: 0,
+    maxWidth: "100%",
+  },
   inputAreaContent: {
     flexShrink: 1,
     width: "100%",

packages/app/src/composer/input/fullscreen-exit.native.ts

@@ -0,0 +1,18 @@
+import { useEffect } from "react";
+import { BackHandler } from "react-native";
+
+/** The hardware back button leaves fullscreen instead of the screen. */
+export function useComposerFullscreenExit(
+  active: boolean,
+  onExit: () => void,
+): ((node: unknown) => void) | undefined {
+  useEffect(() => {
+    if (!active) return;
+    const subscription = BackHandler.addEventListener("hardwareBackPress", () => {
+      onExit();
+      return true;
+    });
+    return () => subscription.remove();
+  }, [active, onExit]);
+  return undefined;
+}

packages/app/src/composer/input/fullscreen-exit.ts

@@ -0,0 +1,23 @@
+import { useOverlayLayer, useWebOverlayRegistration } from "@/lib/overlay-root";
+
+/**
+ * Escape leaves fullscreen before app shortcuts see it. The registration only claims
+ * keys; focus stays where the user left it because the editor never remounts.
+ */
+export function useComposerFullscreenExit(
+  active: boolean,
+  onExit: () => void,
+): ((node: unknown) => void) | undefined {
+  const layer = useOverlayLayer("modal");
+  return useWebOverlayRegistration({
+    active,
+    layer,
+    manageFocus: false,
+    onKeyDown: (event) => {
+      if (event.key !== "Escape") return false;
+      event.preventDefault();
+      onExit();
+      return true;
+    },
+  });
+}

packages/app/src/composer/input/fullscreen-host.native.tsx

@@ -1,57 +0,0 @@
-import { useEffect, type ReactNode } from "react";
-import { Portal } from "@gorhom/portal";
-import { BackHandler, View, useWindowDimensions } from "react-native";
-import { useSafeAreaInsets } from "react-native-safe-area-context";
-import { StyleSheet } from "react-native-unistyles";
-import Animated, { useAnimatedStyle } from "react-native-reanimated";
-import { DEFAULT_FLOATING_PANEL_PORTAL_HOST } from "@/components/ui/floating-panel-portal";
-import { useKeyboardShift } from "@/keyboard/shift";
-
-/** Same-window host keeps the IME attached while escaping the dock's clipping. */
-export function ComposerFullscreenHost({
-  children,
-  onExit,
-  active,
-}: {
-  children: ReactNode;
-  onExit: () => void;
-  active: boolean;
-}) {
-  useEffect(() => {
-    if (!active) return;
-    const handler = BackHandler.addEventListener("hardwareBackPress", () => {
-      onExit();
-      return true;
-    });
-    return () => handler.remove();
-  }, [active, onExit]);
-  const insets = useSafeAreaInsets();
-  const { height } = useWindowDimensions();
-  const { layoutShift } = useKeyboardShift();
-  const frame = useAnimatedStyle(() => ({
-    height: Math.max(0, height - layoutShift.value),
-    paddingTop: insets.top,
-    paddingBottom: insets.bottom,
-    paddingLeft: insets.left,
-    paddingRight: insets.right,
-  }));
-  return (
-    <Portal hostName={DEFAULT_FLOATING_PANEL_PORTAL_HOST}>
-      <View style={[styles.background, !active && styles.hidden]}>
-        <Animated.View style={[{ width: "100%" }, frame]}>{children}</Animated.View>
-      </View>
-    </Portal>
-  );
-}
-
-const styles = StyleSheet.create((theme) => ({
-  hidden: { display: "none" },
-  background: {
-    position: "absolute",
-    top: 0,
-    bottom: 0,
-    left: 0,
-    right: 0,
-    backgroundColor: theme.colors.surface1,
-  },
-}));

packages/app/src/composer/input/fullscreen-host.tsx

@@ -1,77 +0,0 @@
-import { useMemo, useLayoutEffect, useState, type ReactNode } from "react";
-import { createPortal } from "react-dom";
-import { View } from "react-native";
-import {
-  getOverlayRoot,
-  useOverlayLayer,
-  OverlayLayerProvider,
-  useWebOverlayRegistration,
-} from "@/lib/overlay-root";
-
-export function ComposerFullscreenHost({
-  children,
-  onExit,
-  active,
-}: {
-  children: ReactNode;
-  onExit: () => void;
-  active: boolean;
-}) {
-  const layer = useOverlayLayer("modal");
-  const registration = useWebOverlayRegistration({
-    active,
-    layer,
-    onKeyDown: (event) => {
-      if (event.key !== "Escape") return false;
-      event.preventDefault();
-      onExit();
-      return true;
-    },
-  });
-  const [viewport, setViewport] = useState(readVisibleViewport);
-  useLayoutEffect(() => {
-    if (!active) return;
-    const update = () => setViewport(readVisibleViewport());
-    const visualViewport = window.visualViewport;
-    update();
-    visualViewport?.addEventListener("resize", update);
-    visualViewport?.addEventListener("scroll", update);
-    window.addEventListener("resize", update);
-    return () => {
-      visualViewport?.removeEventListener("resize", update);
-      visualViewport?.removeEventListener("scroll", update);
-      window.removeEventListener("resize", update);
-    };
-  }, [active]);
-  const frameStyle = useMemo(
-    () => ({
-      display: active ? ("flex" as const) : ("none" as const),
-      position: "absolute" as const,
-      top: viewport.top,
-      left: viewport.left,
-      width: viewport.width,
-      zIndex: layer,
-      pointerEvents: "auto" as const,
-      height: viewport.height,
-    }),
-    [active, layer, viewport],
-  );
-  return createPortal(
-    <OverlayLayerProvider layer={layer}>
-      <View ref={registration} style={frameStyle}>
-        {children}
-      </View>
-    </OverlayLayerProvider>,
-    getOverlayRoot(),
-  );
-}
-
-function readVisibleViewport() {
-  const viewport = window.visualViewport;
-  return {
-    top: viewport?.offsetTop ?? 0,
-    left: viewport?.offsetLeft ?? 0,
-    width: viewport?.width ?? window.innerWidth,
-    height: viewport?.height ?? window.innerHeight,
-  };
-}

packages/app/src/composer/input/input.tsx

@@ -84,6 +84,7 @@ import {
   computeCanStartDictation,
   resolveComposerSurfacePresentation,
   resolveComposerSurfaceText,
+  resolveRetainedSelection,
   runAlternateSendAction,
   runDefaultSendAction,
   runMessageInputKeyboardAction,
@@ -676,13 +677,7 @@ function ComposerTextSurface(props: ComposerTextSurfaceProps): React.ReactElemen
     );
   }
   return (
-    <View
-      style={[
-        styles.textInputScrollWrapper,
-        props.fullscreen && styles.fullscreenTextSurface,
-        props.compact && !props.fullscreen && styles.compactTextSurface,
-      ]}
-    >
+    <View style={[styles.textInputScrollWrapper, props.fullscreen && styles.fullscreenTextSurface]}>
       {!isWeb && props.compact && !props.fullscreen ? (
         <Text
           accessible={false}
@@ -1040,11 +1035,8 @@ function getComposerInputSnapshot(
   current: ComposerTextInputHandle | null,
   fallbackText: string,
   fallbackSelection: ComposerInputSnapshot["selection"],
-  mountedTextArea?: TextAreaHandle | null,
 ): ComposerInputSnapshot {
-  // The inner DOM ref can detach before the outer editing handle. Keep the mounted
-  // element available until this owner's ref callback captures the remount handoff.
-  const textArea = mountedTextArea ?? getWebTextAreaImpl(current);
+  const textArea = getWebTextAreaImpl(current);
   const text = textArea?.value ?? current?.getText() ?? fallbackText;
   const start = textArea?.selectionStart ?? fallbackSelection.start;
   const end = textArea?.selectionEnd ?? fallbackSelection.end;
@@ -1269,18 +1261,13 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
     const inputWrapperRef = useRef<View | null>(null);
     const textInputRef = useRef<ComposerTextInputHandle | null>(null);
     const isInputFocusedRef = useRef(false);
-    const handoff = editingSession.peekHandoff(textReplacement);
-    const focusIntentRef = useRef(Boolean(handoff?.focused));
-    const valueRef = useRef(handoff?.snapshot.text ?? value);
-    const selectionRef = useRef(
-      handoff?.snapshot.selection ?? { start: value.length, end: value.length },
-    );
+    const focusIntentRef = useRef(false);
+    const valueRef = useRef(value);
+    const selectionRef = useRef({ start: value.length, end: value.length });
     const activeComposerRef = useRef(isActiveComposer);
     activeComposerRef.current = isActiveComposer;
     const [webTextArea, setWebTextArea] = useState<HTMLElement | null>(null);
     const appliedTextReplacementKeyRef = useRef(textReplacement.key);
-    const textReplacementRef = useRef(textReplacement);
-    textReplacementRef.current = textReplacement;
     const webTextareaRef = useRef<HTMLElement | null>(null);
     const updateLiveTextPresence = useCallback((text: string) => {
       const nextHasLiveText = text.trim().length > 0;
@@ -1289,43 +1276,49 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
       setHasLiveText(nextHasLiveText);
     }, []);
 
-    const assignTextInput = useCallback(
-      (input: ComposerTextInputHandle | null) => {
-        const previous = textInputRef.current;
-        if (!input && previous) {
-          editingSession.captureForRemount({
-            snapshot: getComposerInputSnapshot(
-              previous,
-              valueRef.current,
-              selectionRef.current,
-              webTextareaRef.current,
-            ),
-            focused: previous.isFocused() || isInputFocusedRef.current,
-            replacementKey: appliedTextReplacementKeyRef.current,
-          });
-        }
-        textInputRef.current = input;
-        if (isWeb) {
-          const element = getWebTextAreaImpl(input) as HTMLElement | null;
-          webTextareaRef.current = element;
-          setWebTextArea(element);
-        }
-        if (!input) return;
-        const transfer = editingSession.takeHandoff(textReplacementRef.current);
-        if (transfer) {
-          appliedTextReplacementKeyRef.current = textReplacementRef.current.key;
-          valueRef.current = transfer.snapshot.text;
-          updateLiveTextPresence(transfer.snapshot.text);
-          selectionRef.current = transfer.snapshot.selection;
-          input.replaceText(transfer.snapshot.text, transfer.snapshot.selection);
-          if (transfer.focused && activeComposerRef.current) input.focus();
-        }
-      },
-      [editingSession, updateLiveTextPresence],
-    );
+    // One editor stays mounted through every layout mode, so this ref only follows
+    // the editor's own mount and unmount.
+    const assignTextInput = useCallback((input: ComposerTextInputHandle | null) => {
+      textInputRef.current = input;
+      if (!isWeb) return;
+      const element = getWebTextAreaImpl(input) as HTMLElement | null;
+      webTextareaRef.current = element;
+      setWebTextArea(element);
+    }, []);
     useLayoutEffect(() => {
       if (isActiveComposer && focusIntentRef.current) textInputRef.current?.focus();
     }, [isActiveComposer]);
+    // The compact and desktop screens mount the editor in different trees, so a
+    // viewport that crosses the breakpoint remounts it. The draft owner brings the
+    // text back; the session brings the caret and focus intent back. On web the
+    // owner may still hold an unpublished edit while the new editor mounts, so the
+    // caret is placed now against the text on screen and again when the owner's
+    // hydrated text arrives.
+    const retainedSelectionRef = useRef<{ start: number; end: number } | null>(null);
+    useLayoutEffect(() => {
+      const retained = editingSession.takeEditor();
+      if (retained) {
+        const text = textInputRef.current?.getText() ?? valueRef.current;
+        const selection = resolveRetainedSelection(retained.selection, text.length);
+        retainedSelectionRef.current = retained.selection;
+        selectionRef.current = selection;
+        textInputRef.current?.setSelection(selection);
+        if (retained.focused) {
+          focusIntentRef.current = true;
+          if (activeComposerRef.current) textInputRef.current?.focus();
+        }
+      }
+      return () => {
+        editingSession.retainEditor({
+          selection: getComposerInputSnapshot(
+            textInputRef.current,
+            valueRef.current,
+            selectionRef.current,
+          ).selection,
+          focused: isInputFocusedRef.current || focusIntentRef.current,
+        });
+      };
+    }, [editingSession]);
     const getLiveText = useCallback(() => valueRef.current, []);
     const composerHeight = useComposerHeight({
       getText: getLiveText,
@@ -1340,29 +1333,15 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
     const updateComposerHeightForText = measuredComposerHeight?.onTextChange;
     const resetComposerHeight = measuredComposerHeight?.reset;
 
-    const changePresentation = useCallback(
-      (fullscreen: boolean) => {
-        if (editingSession.getFullscreen() === fullscreen) return;
-        const snapshot = getComposerInputSnapshot(
-          textInputRef.current,
-          valueRef.current,
-          selectionRef.current,
-        );
-        editingSession.changePresentation(fullscreen, {
-          snapshot,
-          focused: textInputRef.current?.isFocused() ?? isInputFocusedRef.current,
-          replacementKey: appliedTextReplacementKeyRef.current,
-        });
-        valueRef.current = snapshot.text;
-        selectionRef.current = snapshot.selection;
-      },
-      [editingSession],
-    );
-    const exitFullscreen = useCallback(() => changePresentation(false), [changePresentation]);
+    const exitFullscreen = useCallback(() => editingSession.setFullscreen(false), [editingSession]);
+    const enterFullscreen = useCallback(() => editingSession.setFullscreen(true), [editingSession]);
 
+    // The conversation sizes itself against the inline composer; fullscreen covers it.
     const handleComposerLayout = useCallback(
-      (event: LayoutChangeEvent) => onHeightChange?.(event.nativeEvent.layout.height),
-      [onHeightChange],
+      (event: LayoutChangeEvent) => {
+        if (!isFullscreen) onHeightChange?.(event.nativeEvent.layout.height);
+      },
+      [isFullscreen, onHeightChange],
     );
 
     const replaceText = useCallback(
@@ -1427,8 +1406,15 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
       updateComposerHeightForText?.(valueRef.current, textReplacement.text);
       valueRef.current = textReplacement.text;
       updateLiveTextPresence(textReplacement.text);
+      const retainedSelection =
+        textReplacement.kind === "hydrated" ? retainedSelectionRef.current : null;
+      retainedSelectionRef.current = null;
       if (textReplacement.text === "") {
         textInputRef.current?.reset();
+      } else if (retainedSelection) {
+        const selection = resolveRetainedSelection(retainedSelection, textReplacement.text.length);
+        selectionRef.current = selection;
+        textInputRef.current?.replaceText(textReplacement.text, selection);
       } else {
         textInputRef.current?.replaceText(textReplacement.text);
       }
@@ -1696,17 +1682,6 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
       });
     }, [defaultSendBehavior, isAgentRunning, handleSendMessage, handleQueueMessage, onQueue]);
 
-    const getWebTextArea = useCallback(
-      (): TextAreaHandle | null => getWebTextAreaImpl(textInputRef.current),
-      [],
-    );
-
-    useLayoutEffect(() => {
-      if (isWeb) {
-        webTextareaRef.current = getWebTextArea() as HTMLElement | null;
-      }
-    }, [getWebTextArea, isFullscreen]);
-
     usePasteImagesEffect({
       textarea: webTextArea,
       isConnected,
@@ -1832,6 +1807,8 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
     }, [onFocusChange]);
 
     const handleInputBlur = useCallback(() => {
+      // Fullscreen is nothing but the editor, so a blur there (a retained tab being
+      // hidden, the keyboard dismissed) keeps the intent: showing it again refocuses.
       if (activeComposerRef.current && !isFullscreen) focusIntentRef.current = false;
       isInputFocusedRef.current = false;
       setIsInputFocused(false);
@@ -1888,8 +1865,9 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
         styles.textInput,
         mode.isMonospace && styles.textInputMonospace,
         isFullscreen ? styles.fullscreenTextInput : composerHeightStyle,
+        isCompact && !isFullscreen && styles.compactTextInput,
       ],
-      [composerHeightStyle, mode.isMonospace, isFullscreen],
+      [composerHeightStyle, mode.isMonospace, isFullscreen, isCompact],
     );
     // Static content has no textarea to mirror, so it grows with its own text
     // instead of the measured input height.
@@ -1897,13 +1875,22 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
       () => [styles.textInput, mode.isMonospace && styles.textInputMonospace, styles.readOnlyText],
       [mode.isMonospace],
     );
+    // Fullscreen always shows Send; without content it is disabled, and looks it.
+    const isPresentedSendDisabled = resolvePresentationSendDisabled({
+      fullscreen: isFullscreen,
+      disabled: isSendButtonDisabled,
+      hasText: hasLiveText,
+      attachments,
+      hasExternalContent,
+      allowEmpty: allowEmptySubmit,
+    });
     const sendButtonCombinedStyle = useMemo(
       () => [
         styles.sendButton,
         submitLabel ? styles.sendButtonLabeled : undefined,
-        isSendButtonDisabled && styles.buttonDisabled,
+        isPresentedSendDisabled && styles.buttonDisabled,
       ],
-      [isSendButtonDisabled, submitLabel],
+      [isPresentedSendDisabled, submitLabel],
     );
     const overlayContainerStyle = useMemo(
       () => [styles.overlayContainer, { opacity: surfacePresentation.overlay.opacity }],
@@ -1942,14 +1929,7 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
           canPressLoadingButton={canPressLoadingButton}
           onSubmitLoadingPress={onSubmitLoadingPress}
           onDefaultSendAction={handleDefaultSendAction}
-          isSendButtonDisabled={resolvePresentationSendDisabled({
-            fullscreen: isFullscreen,
-            disabled: isSendButtonDisabled,
-            hasText: hasLiveText,
-            attachments,
-            hasExternalContent,
-            allowEmpty: allowEmptySubmit,
-          })}
+          isSendButtonDisabled={isPresentedSendDisabled}
           submitAccessibilityLabel={submitAccessibilityLabel}
           sendButtonCombinedStyle={sendButtonCombinedStyle}
           isSubmitLoading={isSubmitLoading}
@@ -1968,11 +1948,7 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
         canPressLoadingButton,
         onSubmitLoadingPress,
         handleDefaultSendAction,
-        isSendButtonDisabled,
-        hasLiveText,
-        attachments,
-        hasExternalContent,
-        allowEmptySubmit,
+        isPresentedSendDisabled,
         submitAccessibilityLabel,
         sendButtonCombinedStyle,
         isSubmitLoading,
@@ -2008,9 +1984,7 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
             onBlur={handleInputBlur}
             editable={!isDictating && !isRealtimeVoiceForCurrentAgent && !disabled}
             scrollEnabled={isComposerScrollEnabled}
-            autoFocus={
-              Boolean(editingSession.peekHandoff(textReplacement)?.focused) && isActiveComposer
-            }
+            autoFocus={false}
             onKeyPress={shouldHandleWebKeyPress ? handleDesktopKeyPress : undefined}
             onSelectionChange={handleSelectionChange}
             onPasteImages={onPasteImages}
@@ -2029,8 +2003,6 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
       [
         readOnly,
         textReplacement,
-        editingSession,
-        isActiveComposer,
         assignTextInput,
         textInputStyle,
         readOnlyTextStyle,
@@ -2162,11 +2134,10 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
         handleRealtimeVoiceStop,
       ],
     );
-    const enterFullscreen = useCallback(() => changePresentation(true), [changePresentation]);
     return (
       <View
         ref={rootRef}
-        style={styles.container}
+        style={isFullscreen ? styles.fullscreenContainer : styles.container}
         testID="message-input-root"
         onLayout={handleComposerLayout}
       >
@@ -2177,8 +2148,7 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
         />
         <ComposerInputPresentation
           fullscreen={isFullscreen}
-          iconSize={buttonIconSize}
-          active={isActiveComposer}
+          sendIconSize={buttonIconSize}
           surface={textSurface}
           toolbar={toolbar}
           send={sendButton}
@@ -2207,6 +2177,10 @@ const styles = StyleSheet.create((theme: Theme) => ({
     flexShrink: 1,
     position: "relative",
   },
+  fullscreenContainer: {
+    flex: 1,
+    position: "relative",
+  },
   inputWrapper: {
     flexShrink: 1,
     flexDirection: "column",
@@ -2241,14 +2215,18 @@ const styles = StyleSheet.create((theme: Theme) => ({
   inputWrapperReadOnly: {
     borderStyle: "dotted",
   },
-  compactTextSurface: { paddingRight: 36 },
+  // The band the fullscreen glyph sits in is the input's own padding, so a tap
+  // anywhere in it (under the glyph, or where the glyph would be) is a tap on the
+  // editor: it focuses, shows the keyboard, and places the caret. Reserved whether
+  // or not the glyph shows, so text never reflows when it appears.
+  compactTextInput: { paddingRight: 36 },
   fullscreenTextSurface: { flex: 1, minHeight: 0 },
   fullscreenTextInput: { flex: 1, height: "100%", textAlignVertical: "top" },
   lineMeasurement: {
     position: "absolute",
     top: 0,
     left: 0,
-    right: 36,
+    right: 0,
     opacity: 0,
     maxHeight: undefined,
     minHeight: undefined,

packages/app/src/composer/input/presentation.tsx

@@ -3,19 +3,31 @@ import { View, type ViewProps } from "react-native";
 import { Maximize2, Minimize2 } from "lucide-react-native";
 import { useTranslation } from "react-i18next";
 import { Button } from "@/components/ui/button";
+import { ComposerFullscreenBody, ComposerFullscreenFooter } from "@/composer/dock";
+import { useComposerKeyboardScope } from "@/composer/keyboard-scope";
 import { isWeb } from "@/constants/platform";
+import { ICON_SIZE } from "@/styles/theme";
 import { StyleSheet } from "react-native-unistyles";
-import { ComposerFullscreenHost } from "./fullscreen-host";
+import { useComposerFullscreenExit } from "./fullscreen-exit";
+import { resolveGlyphRailOffset } from "./state";
+
+const CONTROL_SIZE = 28;
+const FULLSCREEN_GLYPH_SIZE = ICON_SIZE.md;
 
 function keepEditorFocused(event: import("react-native").PointerEvent) {
   if (isWeb) event.preventDefault();
 }
 
-/** Both presentations receive the same editing surface and send capability. */
+/**
+ * One tree for both layout modes. The editing surface keeps its position so the
+ * mounted editor, its native buffer, selection, and focus survive every toggle;
+ * only the chrome around it changes. Fullscreen shows exit top right and Send
+ * bottom right, both on the rail the inline Send button uses; a send error sits
+ * in the same footer as Send.
+ */
 export function ComposerInputPresentation({
   fullscreen,
-  iconSize,
-  active,
+  sendIconSize,
   surface,
   toolbar,
   send,
@@ -30,8 +42,7 @@ export function ComposerInputPresentation({
   overlay,
 }: {
   fullscreen: boolean;
-  iconSize: number;
-  active: boolean;
+  sendIconSize: number;
   surface: ReactNode;
   toolbar: ReactNode;
   send: ReactNode;
@@ -46,55 +57,33 @@ export function ComposerInputPresentation({
   overlay: ReactNode;
 }) {
   const { t } = useTranslation();
-  // ArrowUp ends at x19; the fullscreen glyphs end at x21 in Lucide's 24px viewBox.
-  // Compensate for that difference to align visible ink with Send, not just boxes.
-  const railAdjustment = iconSize / 12;
+  // A retained tab keeps its fullscreen editor mounted while hidden; the global exit
+  // action (Escape, hardware back) belongs only to the pane the user is in.
+  const { isActiveComposer } = useComposerKeyboardScope();
+  const exitScopeRef = useComposerFullscreenExit(fullscreen && isActiveComposer, onExit);
+  const railOffset = resolveGlyphRailOffset({
+    controlSize: CONTROL_SIZE,
+    sendIconSize,
+    glyphIconSize: FULLSCREEN_GLYPH_SIZE,
+  });
   const maximizeIcon = useCallback(
-    (color: string) => <Maximize2 color={color} size={iconSize} />,
-    [iconSize],
+    (color: string) => <Maximize2 color={color} size={FULLSCREEN_GLYPH_SIZE} />,
+    [],
   );
   const minimizeIcon = useCallback(
-    (color: string) => <Minimize2 color={color} size={iconSize} />,
-    [iconSize],
+    (color: string) => <Minimize2 color={color} size={FULLSCREEN_GLYPH_SIZE} />,
+    [],
   );
-  const enterStyle = useMemo(
-    () => [styles.fullscreenButton, { right: -6 + railAdjustment }],
-    [railAdjustment],
-  );
-  const exitStyle = useMemo(
-    () => [styles.iconButton, { marginRight: railAdjustment }],
-    [railAdjustment],
-  );
-  if (!fullscreen)
-    return (
-      <>
-        <View ref={inputWrapperRef} style={inputWrapperStyle} pointerEvents={inputPointerEvents}>
-          {attachmentSlot}
-          <View style={styles.inlineTextSurface}>
-            {surface}
-            {showFullscreenButton ? (
-              <Button
-                variant="ghost"
-                size="xs"
-                accessibilityLabel={t("composer.input.fullscreen")}
-                leftIcon={maximizeIcon}
-                onPointerDown={keepEditorFocused}
-                onPress={onEnter}
-                style={enterStyle}
-                hitSlop={8}
-              >
-                {null}
-              </Button>
-            ) : null}
-          </View>
-          {toolbar}
-        </View>
-        {overlay}
-      </>
-    );
+  // The toolbar row bleeds 6px past the input padding; the inline glyph sits on that edge.
+  const enterStyle = useMemo(() => [styles.enterButton, { right: -6 + railOffset }], [railOffset]);
+  const exitStyle = useMemo(() => [styles.iconButton, { marginRight: railOffset }], [railOffset]);
   return (
-    <ComposerFullscreenHost onExit={onExit} active={active}>
-      <View style={styles.fullscreen} testID="composer-fullscreen">
+    <View
+      ref={exitScopeRef}
+      style={fullscreen ? styles.fullscreen : styles.inline}
+      testID={fullscreen ? "composer-fullscreen" : undefined}
+    >
+      {fullscreen ? (
         <View style={styles.exitRow}>
           <Button
             variant="ghost"
@@ -109,28 +98,60 @@ export function ComposerInputPresentation({
             {null}
           </Button>
         </View>
-        {surface}
-        {error}
-        <View style={styles.sendRow}>{send}</View>
-      </View>
-    </ComposerFullscreenHost>
+      ) : null}
+      <ComposerFullscreenBody fullscreen={fullscreen}>
+        <View
+          ref={inputWrapperRef}
+          style={fullscreen ? styles.fullscreenInputWrapper : inputWrapperStyle}
+          pointerEvents={inputPointerEvents}
+        >
+          {fullscreen ? null : attachmentSlot}
+          <View style={fullscreen ? styles.fullscreenTextSurface : styles.inlineTextSurface}>
+            {surface}
+            {showFullscreenButton && !fullscreen ? (
+              <Button
+                variant="ghost"
+                size="xs"
+                accessibilityLabel={t("composer.input.fullscreen")}
+                leftIcon={maximizeIcon}
+                onPointerDown={keepEditorFocused}
+                onPress={onEnter}
+                style={enterStyle}
+                hitSlop={8}
+              >
+                {null}
+              </Button>
+            ) : null}
+          </View>
+          {fullscreen ? null : toolbar}
+        </View>
+      </ComposerFullscreenBody>
+      {fullscreen ? (
+        <ComposerFullscreenFooter style={styles.footer}>
+          {error}
+          <View style={styles.sendRow}>{send}</View>
+        </ComposerFullscreenFooter>
+      ) : null}
+      {overlay}
+    </View>
   );
 }
 
 const styles = StyleSheet.create((theme) => ({
+  inline: { flexShrink: 1, position: "relative" },
   inlineTextSurface: { flexShrink: 1, position: "relative" },
   iconButton: {
-    width: 28,
-    height: 28,
+    width: CONTROL_SIZE,
+    height: CONTROL_SIZE,
     padding: 0,
     borderWidth: 0,
     borderRadius: theme.borderRadius.full,
   },
-  fullscreenButton: {
+  enterButton: {
     position: "absolute",
     top: 0,
-    width: 28,
-    height: 28,
+    width: CONTROL_SIZE,
+    height: CONTROL_SIZE,
     padding: 0,
     borderWidth: 0,
     borderRadius: theme.borderRadius.full,
@@ -141,6 +162,10 @@ const styles = StyleSheet.create((theme) => ({
     padding: theme.spacing[4],
     gap: theme.spacing[3],
   },
+  fullscreenInputWrapper: { flex: 1, minHeight: 0 },
+  fullscreenTextSurface: { flex: 1, minHeight: 0 },
   exitRow: { alignItems: "flex-end", flexShrink: 0 },
-  sendRow: { flexShrink: 0, alignItems: "flex-end" },
+  // The send error rides the keyboard with Send; below the body it would sit behind it.
+  footer: { flexShrink: 0, gap: theme.spacing[3] },
+  sendRow: { alignItems: "flex-end" },
 }));

packages/app/src/composer/input/state.test.ts

@@ -5,6 +5,8 @@ import {
   resolveActiveSendBehavior,
   resolveComposerSurfacePresentation,
   resolveComposerSurfaceText,
+  resolveGlyphRailOffset,
+  resolveRetainedSelection,
   runAlternateSendAction,
   runDefaultSendAction,
   runMessageInputKeyboardAction,
@@ -333,10 +335,30 @@ describe("composer surface text", () => {
     );
   });
 
-  it("uses the live handoff when its replacement has already been applied", () => {
+  it("keeps the live buffer when the initial publication is already applied", () => {
     const replacement = { kind: "initial" as const, key: "draft:0", text: "Stale publication" };
-    expect(resolveComposerSurfaceText("Live remount handoff", replacement, "draft:0")).toBe(
-      "Live remount handoff",
+    expect(resolveComposerSurfaceText("Live edited draft", replacement, "draft:0")).toBe(
+      "Live edited draft",
     );
   });
 });
+
+describe("retained selection", () => {
+  it("keeps a caret that fits and clamps one that no longer does", () => {
+    expect(resolveRetainedSelection({ start: 4, end: 17 }, 40)).toEqual({ start: 4, end: 17 });
+    expect(resolveRetainedSelection({ start: 4, end: 17 }, 10)).toEqual({ start: 4, end: 10 });
+    expect(resolveRetainedSelection({ start: 12, end: 17 }, 10)).toEqual({ start: 10, end: 10 });
+    expect(resolveRetainedSelection({ start: -1, end: 3 }, 10)).toEqual({ start: 0, end: 3 });
+  });
+});
+
+describe("fullscreen glyph rail", () => {
+  it("nudges 16px fullscreen glyphs onto the Send arrow's ink edge", () => {
+    expect(
+      resolveGlyphRailOffset({ controlSize: 28, sendIconSize: 16, glyphIconSize: 16 }),
+    ).toBeCloseTo(4 / 3);
+    expect(
+      resolveGlyphRailOffset({ controlSize: 28, sendIconSize: 20, glyphIconSize: 16 }),
+    ).toBeCloseTo(1 / 6);
+  });
+});

packages/app/src/composer/input/state.ts

@@ -193,6 +193,24 @@ export async function stopRealtimeVoice(ctx: StopRealtimeVoiceContext): Promise<
   await ctx.voice.stopVoice();
 }
 
+/**
+ * Offset that aligns a glyph's visible ink with the Send arrow's ink when both sit in
+ * equal controls on the same right rail. In Lucide's 24px viewBox ArrowUp ends at
+ * x19 while Maximize2/Minimize2 end at x21, so equal boxes leave the fullscreen
+ * glyphs visibly past the arrow.
+ */
+export function resolveGlyphRailOffset(input: {
+  controlSize: number;
+  sendIconSize: number;
+  glyphIconSize: number;
+}): number {
+  const arrowInkInset =
+    (input.controlSize - input.sendIconSize) / 2 + (5 * input.sendIconSize) / 24;
+  const glyphInkInset =
+    (input.controlSize - input.glyphIconSize) / 2 + (3 * input.glyphIconSize) / 24;
+  return arrowInkInset - glyphInkInset;
+}
+
 export function resolveComposerSurfaceText(
   liveText: string,
   replacement: TextReplacement,
@@ -200,3 +218,13 @@ export function resolveComposerSurfaceText(
 ): string {
   return replacement.key === appliedReplacementKey ? liveText : replacement.text;
 }
+
+/** A retained caret must fit the text the remounted editor shows. */
+export function resolveRetainedSelection(
+  retained: { start: number; end: number },
+  textLength: number,
+): { start: number; end: number } {
+  const end = Math.min(Math.max(retained.end, 0), textLength);
+  const start = Math.min(Math.max(retained.start, 0), end);
+  return { start, end };
+}

packages/app/src/composer/types.ts

@@ -9,8 +9,12 @@ export interface MessagePayload {
   forceSend?: boolean;
 }
 
+/**
+ * Text the draft owner hands the editor. `hydrated` is the owner's answer to a mount:
+ * the draft's text as persisted or still pending from the editor that unmounted.
+ */
 export interface TextReplacement {
-  kind: "initial" | "replace";
+  kind: "initial" | "hydrated" | "replace";
   key: string;
   text: string;
 }

packages/app/src/file-pane/editor/view.web.tsx

@@ -165,4 +165,7 @@ const FRAME_STYLE = {
   minHeight: 0,
   minWidth: 0,
 } as const;
-const HOST_STYLE = { flex: 1, minHeight: 0, overflow: "hidden" } as const;
+// CodeMirror's scrollIntoView scrolls every overflowing ancestor and stops at a fixed or sticky
+// one. Sticky (with no offsets it lays out like relative) keeps line reveals inside the editor, so
+// they don't shift the host around it, such as the compact workspace sheet.
+const HOST_STYLE = { flex: 1, minHeight: 0, overflow: "hidden", position: "sticky" } as const;

packages/app/src/hooks/use-file-download.ts

@@ -1,5 +1,5 @@
 import { useCallback, useMemo } from "react";
-import { useHosts } from "@/runtime/host-runtime";
+import { getHostRuntimeStore, useHosts } from "@/runtime/host-runtime";
 import { useDownloadStore } from "@/stores/download-store";
 import { useFileExplorerActions } from "@/hooks/use-file-explorer-actions";
 
@@ -12,8 +12,9 @@ interface UseFileDownloadParams {
 /**
  * Returns a stable callback that downloads a single workspace file by its
  * workspace-relative path. Shared by the file explorer tree and the git diff
- * pane so both surfaces download through the same host token + download-store
- * pipeline instead of duplicating the plumbing.
+ * pane so both surfaces download through the same download-store pipeline instead
+ * of duplicating the plumbing: the HTTP token download over a direct TCP connection,
+ * the session socket over anything else.
  */
 export function useFileDownload({
   serverId,
@@ -30,7 +31,7 @@ export function useFileDownload({
     () => workspaceId?.trim() || normalizedWorkspaceRoot,
     [normalizedWorkspaceRoot, workspaceId],
   );
-  const { requestFileDownloadToken } = useFileExplorerActions({
+  const { requestFileDownloadToken, requestFileBytes } = useFileExplorerActions({
     serverId,
     workspaceId,
     workspaceRoot: normalizedWorkspaceRoot,
@@ -48,9 +49,18 @@ export function useFileDownload({
         fileName,
         path,
         daemonProfile,
+        activeConnectionId: getHostRuntimeStore().getSnapshot(serverId)?.activeConnectionId ?? null,
         requestFileDownloadToken: (targetPath) => requestFileDownloadToken(targetPath),
+        readFile: requestFileBytes,
       });
     },
-    [daemonProfile, requestFileDownloadToken, serverId, startDownload, workspaceScopeId],
+    [
+      daemonProfile,
+      requestFileBytes,
+      requestFileDownloadToken,
+      serverId,
+      startDownload,
+      workspaceScopeId,
+    ],
   );
 }

packages/app/src/hooks/use-file-explorer-actions.ts

@@ -253,6 +253,21 @@ export function useFileExplorerActions(params: { serverId: string } & FileExplor
     [client, normalizedWorkspaceRoot, t],
   );
 
+  const requestFileBytes = useCallback(
+    async (path: string, maxBytes: number) => {
+      if (!normalizedWorkspaceRoot) {
+        throw new Error(t("workspace.fileExplorer.states.unavailable"));
+      }
+      if (!client) {
+        throw new Error(t("workspace.terminal.hostDisconnected"));
+      }
+      // No request timeout: a large file over a slow relay legitimately takes longer than the
+      // 60 s default, and a dead connection still rejects on disconnect.
+      return client.readFile(normalizedWorkspaceRoot, path, undefined, maxBytes, 0);
+    },
+    [client, normalizedWorkspaceRoot, t],
+  );
+
   const createEntry = useCallback(
     async (input: { parentPath: string; name: string; kind: "file" | "directory" }) => {
       if (!client || !normalizedWorkspaceRoot) {
@@ -342,6 +357,7 @@ export function useFileExplorerActions(params: { serverId: string } & FileExplor
     requestDirectoryListing,
     requestFilePreview,
     requestFileDownloadToken,
+    requestFileBytes,
     createEntry,
     renameEntry,
     duplicateEntry,

packages/app/src/hooks/use-settings/storage.test.ts

@@ -15,6 +15,7 @@ import {
   parseClampedFontSize,
   parseTerminalScrollbackLines,
   resolveContentMaxWidth,
+  sanitizeFontFamily,
   saveAppSettings,
   type SettingsDeps,
 } from "./storage";
@@ -1094,3 +1095,34 @@ describe("content max width", () => {
     expect((await load("wide")).contentMaxWidth).toBeNull();
   });
 });
+
+describe("font family CSS safety", () => {
+  it.each(["'foo", '"foo', "Menlo, 'foo", "foo\\", "foo/*", "foo(", "foo["])(
+    "rejects unfinished CSS syntax: %s",
+    (value) => expect(sanitizeFontFamily(value)).toBeNull(),
+  );
+
+  it.each([
+    "Menlo",
+    "'Fira Code', monospace",
+    '"Fira Code", monospace',
+    "'Font\\'s name'",
+    "Font\\ Name",
+    "'Font (Mono)'",
+    "'Font [Mono]'",
+  ])("preserves complete font families: %s", (value) =>
+    expect(sanitizeFontFamily(value)).toBe(value),
+  );
+
+  it.each(["uiFontFamily", "monoFontFamily"])(
+    "recovers a persisted unmatched quote in %s",
+    async (field) => {
+      const deps = makeDeps({
+        storage: createInMemoryKeyValueStorage({
+          [APP_SETTINGS_KEY]: JSON.stringify({ [field]: "'foo" }),
+        }),
+      });
+      expect(await loadAppSettingsFromStorage(deps)).toMatchObject({ [field]: "" });
+    },
+  );
+});

packages/app/src/hooks/use-settings/storage.ts

@@ -522,7 +522,24 @@ export function sanitizeFontFamily(value: unknown): string | null {
   if ([...trimmed].some((char) => char.charCodeAt(0) <= 0x1f)) {
     return null; // control chars would corrupt the font-family string
   }
-  return trimmed; // quotes/commas are legit in stacks
+  // Unistyles serializes theme values into one shared stylesheet. An unfinished
+  // string, escape, comment, or block consumes the declarations that follow.
+  let quote: string | null = null;
+  let escaped = false;
+  for (const char of trimmed) {
+    if (escaped) {
+      escaped = false;
+    } else if (char === "\\") {
+      escaped = true;
+    } else if (quote !== null) {
+      if (char === quote) quote = null;
+    } else if (char === "'" || char === '"') {
+      quote = char;
+    } else if (/[()[\]/*]/.test(char)) {
+      return null;
+    }
+  }
+  return quote === null && !escaped ? trimmed : null;
 }
 
 async function loadLegacyDesktopSettingsFromStorage(storage: KeyValueStorage): Promise<{

packages/app/src/i18n/resources/ar.ts

@@ -613,6 +613,9 @@ export const ar: TranslationResources = {
       updateHost: "حدّث المضيف لاستخدام عارض الطرفية الأصلي.",
       unableToSubscribe: "غير قادر على الاشتراك في المحطة",
     },
+    sheet: {
+      openAsTab: "فتح كعلامة تبويب",
+    },
     tabs: {
       loading: "تحميل...",
       modified: "تغييرات غير محفوظة",

packages/app/src/i18n/resources/en.ts

@@ -610,6 +610,9 @@ export const en = {
       updateHost: "Update the host to use the native terminal renderer.",
       unableToSubscribe: "Unable to subscribe to terminal",
     },
+    sheet: {
+      openAsTab: "Open as tab",
+    },
     tabs: {
       loading: "Loading...",
       modified: "Unsaved changes",

packages/app/src/i18n/resources/es.ts

@@ -619,6 +619,9 @@ export const es: TranslationResources = {
       updateHost: "Actualiza el host para usar el renderizador de terminal nativo.",
       unableToSubscribe: "No se puede suscribir al terminal",
     },
+    sheet: {
+      openAsTab: "Abrir como pestaña",
+    },
     tabs: {
       loading: "Cargando...",
       modified: "Cambios sin guardar",

packages/app/src/i18n/resources/fr.ts

@@ -618,6 +618,9 @@ export const fr: TranslationResources = {
       updateHost: "Mettez à jour l’hôte pour utiliser le rendu natif du terminal.",
       unableToSubscribe: "Impossible de s’abonner au terminal",
     },
+    sheet: {
+      openAsTab: "Ouvrir dans un onglet",
+    },
     tabs: {
       loading: "Chargement…",
       modified: "Modifications non enregistrées",

packages/app/src/i18n/resources/ja.ts

@@ -619,6 +619,9 @@ export const ja: TranslationResources = {
       updateHost: "ネイティブターミナルを使用するにはホストを更新してください。",
       unableToSubscribe: "ターミナルに接続できません",
     },
+    sheet: {
+      openAsTab: "タブで開く",
+    },
     tabs: {
       loading: "読み込み中...",
       modified: "未保存の変更",

packages/app/src/i18n/resources/ko.ts

@@ -614,6 +614,9 @@ export const ko: TranslationResources = {
       updateHost: "기본 터미널 렌더러를 사용하도록 호스트를 업데이트합니다.",
       unableToSubscribe: "터미널을 구독할 수 없습니다",
     },
+    sheet: {
+      openAsTab: "탭으로 열기",
+    },
     tabs: {
       loading: "불러오는 중...",
       modified: "저장되지 않은 변경사항",

packages/app/src/i18n/resources/pt-BR.ts

@@ -618,6 +618,9 @@ export const ptBR: TranslationResources = {
       updateHost: "Atualize o host para usar o renderizador de terminal nativo.",
       unableToSubscribe: "Não foi possível assinar o terminal",
     },
+    sheet: {
+      openAsTab: "Abrir como aba",
+    },
     tabs: {
       loading: "Carregando...",
       modified: "Alterações não salvas",

packages/app/src/i18n/resources/ru.ts

@@ -620,6 +620,9 @@ export const ru: TranslationResources = {
       updateHost: "Обновите хост, чтобы использовать нативный рендерер терминала.",
       unableToSubscribe: "Не удалось подключиться к терминалу",
     },
+    sheet: {
+      openAsTab: "Открыть во вкладке",
+    },
     tabs: {
       loading: "Загрузка...",
       modified: "Несохранённые изменения",

packages/app/src/i18n/resources/zh-CN.ts

@@ -613,6 +613,9 @@ export const zhCN: TranslationResources = {
       updateHost: "请更新主机以使用原生终端渲染器。",
       unableToSubscribe: "无法订阅 Terminal",
     },
+    sheet: {
+      openAsTab: "作为标签页打开",
+    },
     tabs: {
       loading: "正在加载...",
       modified: "未保存的更改",

packages/app/src/panels/agent-panel.tsx

@@ -27,6 +27,11 @@ import { FileDropZone } from "@/components/file-drop/file-drop-zone";
 import { useRetainedPanelActive } from "@/components/retained-panel";
 import { RetainedChatContent } from "./retained-chat-content";
 import { Composer } from "@/composer";
+import {
+  useComposerEditingSession,
+  useComposerFullscreen,
+  type ComposerEditingSession,
+} from "@/composer/editing-session";
 import { useWorkspaceHasDiffStat } from "@/composer/workspace-diff-stat";
 import {
   resolveComposerTrackControlClearance,
@@ -1153,6 +1158,11 @@ const ChatAgentReadyContent = memo(function ChatAgentReadyContent({
   onOpenWorkspaceFile?: (request: WorkspaceFileOpenRequest) => void;
 }) {
   const { t } = useTranslation();
+  // The workspace sheet is for looking; Open as tab brings the agent back with its composer.
+  const showsComposer = usePaneContext().host !== "sheet";
+  // The dock lays out fullscreen for the same session the composer edits in.
+  const composerEditingSession = useComposerEditingSession("chat");
+  const isComposerFullscreen = useComposerFullscreen(composerEditingSession);
   const subagentRows = useSubagentsForParent({ serverId, parentAgentId: agentId });
   const tasks = useSessionStore((state): TodoEntry[] | undefined =>
     state.sessions[serverId]?.agentTasks.get(agentId),
@@ -1216,7 +1226,7 @@ const ChatAgentReadyContent = memo(function ChatAgentReadyContent({
       composerState,
     ],
   );
-  const composerSection = (
+  const composerSection = showsComposer ? (
     <RenderProfile id={`AgentComposerSection:${agentId}`}>
       <AgentComposerSection
         agentId={agentId}
@@ -1227,13 +1237,14 @@ const ChatAgentReadyContent = memo(function ChatAgentReadyContent({
         cwd={cwd}
         isSubmitLoading={false}
         agentInputDraft={agentInputDraft}
+        editingSession={composerEditingSession}
         onAttentionInputFocus={onAttentionInputFocus}
         onAttentionPromptSend={onAttentionPromptSend}
         onComposerHeightChange={handleComposerHeightChange}
         onMessageSent={handleMessageSent}
       />
     </RenderProfile>
-  );
+  ) : null;
   const streamContent = (
     <View style={animatedStaticStyles.content}>
       <RenderProfile id={`AgentStreamSection:${agentId}`}>
@@ -1290,7 +1301,7 @@ const ChatAgentReadyContent = memo(function ChatAgentReadyContent({
   );
 
   const dock = (
-    <ChatSurface disabled={isArchivingCurrentAgent}>
+    <ChatSurface disabled={isArchivingCurrentAgent} fullscreen={isComposerFullscreen}>
       {dockContent}
       {composerSection}
       {dockOverlay}
@@ -1321,13 +1332,15 @@ const ChatAgentReadyContent = memo(function ChatAgentReadyContent({
 function ChatSurface({
   children,
   disabled,
+  fullscreen,
 }: {
   children: [ReactNode, ReactNode, ReactNode];
   disabled: boolean;
+  fullscreen: boolean;
 }) {
   return (
     <FileDropZone style={styles.container} disabled={disabled}>
-      <ComposerDock>{children}</ComposerDock>
+      <ComposerDock fullscreen={fullscreen}>{children}</ComposerDock>
     </FileDropZone>
   );
 }
@@ -1471,6 +1484,7 @@ const AgentComposerSection = memo(function AgentComposerSection({
   cwd,
   isSubmitLoading,
   agentInputDraft,
+  editingSession,
   onAttentionInputFocus,
   onAttentionPromptSend,
   onComposerHeightChange,
@@ -1484,6 +1498,7 @@ const AgentComposerSection = memo(function AgentComposerSection({
   cwd: string;
   isSubmitLoading: boolean;
   agentInputDraft: AgentInputDraft;
+  editingSession: ComposerEditingSession;
   onAttentionInputFocus: () => void;
   onAttentionPromptSend: () => void;
   onComposerHeightChange: (height: number) => void;
@@ -1507,6 +1522,7 @@ const AgentComposerSection = memo(function AgentComposerSection({
       cwd={cwd}
       isSubmitLoading={isSubmitLoading}
       agentInputDraft={agentInputDraft}
+      editingSession={editingSession}
       onAttentionInputFocus={onAttentionInputFocus}
       onAttentionPromptSend={onAttentionPromptSend}
       onComposerHeightChange={onComposerHeightChange}
@@ -1522,6 +1538,7 @@ function ActiveAgentComposer({
   cwd,
   isSubmitLoading,
   agentInputDraft,
+  editingSession,
   onAttentionInputFocus,
   onAttentionPromptSend,
   onComposerHeightChange,
@@ -1533,6 +1550,7 @@ function ActiveAgentComposer({
   cwd: string;
   isSubmitLoading: boolean;
   agentInputDraft: AgentInputDraft;
+  editingSession: ComposerEditingSession;
   onAttentionInputFocus: () => void;
   onAttentionPromptSend: () => void;
   onComposerHeightChange: (height: number) => void;
@@ -1629,6 +1647,7 @@ function ActiveAgentComposer({
         onChangeAttachments={agentInputDraft.setAttachments}
         cwd={cwd}
         clearDraft={agentInputDraft.clear}
+        editingSession={editingSession}
         autoFocus
         autoFocusKey={String(agentInputDraft.attachmentFocusRequestId)}
         isSubmitLoading={isSubmitLoading}
@@ -1721,6 +1740,8 @@ const animatedStaticStyles = RNStyleSheet.create({
   inputAreaWrapper: {
     width: "100%",
     flexShrink: 1,
+    // Content-sized inline; fills the dock's fullscreen slot.
+    flexGrow: 1,
   },
 });
 

packages/app/src/panels/agent-tracks.tsx

@@ -3,7 +3,7 @@ import { WorkspaceDiffStatPill } from "@/composer/diff-stat-pill";
 import { useWorkspaceHasDiffStat } from "@/composer/workspace-diff-stat";
 import { AgentTaskList } from "@/composer/task-list";
 import { ComposerTrackBar } from "@/composer/tracks";
-import { supportsDesktopPaneSplits, useIsCompactFormFactor } from "@/constants/layout";
+import { useIsCompactFormFactor } from "@/constants/layout";
 import { usePaneContext } from "@/panels/pane-context";
 import { useSettings } from "@/hooks/use-settings";
 import { PluginComposerPills } from "@/plugins";
@@ -17,7 +17,7 @@ import {
 import { SubagentsTrack } from "@/subagents/track";
 import type { TodoEntry } from "@/types/stream";
 import { navigateToAgent } from "@/utils/navigate-to-agent";
-import { buildWorkspaceTabPersistenceKey } from "@/workspace-tabs/model";
+import { buildWorkspaceTabPersistenceKey, type WorkspaceTabTarget } from "@/workspace-tabs/model";
 import { openPreferredWorkspaceTarget } from "@/workspace-tabs/open-beside";
 import { openComposerChanges } from "@/workspace-tabs/open-supporting-view";
 
@@ -49,10 +49,9 @@ export const AgentTracks = memo(function AgentTracks({
   onArchiveFinished: () => void;
   hasPluginComposerPills: boolean;
 }): ReactElement | null {
-  const { tabId, openTab } = usePaneContext();
+  const { tabId } = usePaneContext();
   const hasWorkspaceDiffStat = useWorkspaceHasDiffStat(serverId, workspaceId);
   const isCompact = useIsCompactFormFactor();
-  const canSplit = supportsDesktopPaneSplits() && !isCompact;
   const openInSidePane = useSettings((settings) => settings.openInSidePane);
   const workspaceKey = buildWorkspaceTabPersistenceKey({ serverId, workspaceId });
   const canDetachSubagents = useSessionStore(
@@ -60,45 +59,36 @@ export const AgentTracks = memo(function AgentTracks({
   );
   const archiveSubagent = useArchiveSubagent({ serverId });
   const detachSubagent = useDetachSubagent({ serverId });
+  const openSubagentTarget = useCallback(
+    (target: WorkspaceTabTarget) => {
+      openPreferredWorkspaceTarget({
+        workspaceKey,
+        target,
+        source: "subagents",
+        preferences: openInSidePane,
+        parentTabId: tabId,
+      });
+    },
+    [openInSidePane, tabId, workspaceKey],
+  );
   const handleOpenSubagent = useCallback(
     (subagentId: string) => {
       const session = useSessionStore.getState().sessions[serverId];
       const agent = session?.agents.get(subagentId) ?? session?.agentDetails.get(subagentId);
+      // A subagent in another workspace lives in that workspace's tabs.
       if (agent?.workspaceId && agent.workspaceId !== workspaceId) {
         navigateToAgent({ serverId, agentId: subagentId });
         return;
       }
-      if (canSplit && workspaceKey) {
-        openPreferredWorkspaceTarget({
-          isCompact,
-          workspaceKey,
-          target: { kind: "agent", agentId: subagentId },
-          source: "subagents",
-          preferences: openInSidePane,
-          parentTabId: tabId,
-        });
-        return;
-      }
-      navigateToAgent({ serverId, agentId: subagentId });
+      openSubagentTarget({ kind: "agent", agentId: subagentId });
     },
-    [canSplit, isCompact, openInSidePane, serverId, tabId, workspaceId, workspaceKey],
+    [openSubagentTarget, serverId, workspaceId],
   );
   const handleOpenProviderSubagent = useCallback(
     (parentAgentId: string, subagentId: string) => {
-      if (canSplit && workspaceKey) {
-        openPreferredWorkspaceTarget({
-          isCompact,
-          workspaceKey,
-          target: { kind: "provider_subagent", parentAgentId, subagentId },
-          source: "subagents",
-          preferences: openInSidePane,
-          parentTabId: tabId,
-        });
-        return;
-      }
-      openTab({ kind: "provider_subagent", parentAgentId, subagentId });
+      openSubagentTarget({ kind: "provider_subagent", parentAgentId, subagentId });
     },
-    [canSplit, isCompact, openInSidePane, openTab, tabId, workspaceKey],
+    [openSubagentTarget],
   );
   const handleOpenChanges = useCallback(() => {
     if (!workspaceKey) {

packages/app/src/panels/panel-instance-attributes.ts

@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useMemo, useSyncExternalStore } from "react";
 import { usePaneContext } from "@/panels/pane-context";
+import { buildWorkspaceTabPersistenceKey } from "@/workspace-tabs/model";
 
 export interface PanelInstanceIdentity {
   serverId: string;
@@ -18,8 +19,20 @@ const listenersByPanel = new Map<string, Set<() => void>>();
 const allListeners = new Set<() => void>();
 let attributesRevision = 0;
 
+function buildWorkspacePanelKey(workspaceKey: string, tabId: string): string {
+  return `${workspaceKey}:${tabId}`;
+}
+
 export function buildPanelInstanceKey(identity: PanelInstanceIdentity): string {
-  return `${identity.serverId}:${identity.workspaceId}:${identity.tabId}`;
+  return buildWorkspacePanelKey(buildWorkspaceTabPersistenceKey(identity) ?? "", identity.tabId);
+}
+
+/** Looks a panel up by the workspace key the layout store uses. */
+export function getWorkspacePanelAttributes(
+  workspaceKey: string,
+  tabId: string,
+): PanelInstanceAttributes {
+  return attributesByPanel.get(buildWorkspacePanelKey(workspaceKey, tabId)) ?? DEFAULT_ATTRIBUTES;
 }
 
 export function getPanelInstanceAttributes(

packages/app/src/panels/panel-manifest.test.ts

@@ -18,6 +18,14 @@ describe("panel manifest", () => {
     expect(panelSupportsHost("setup", "explorer")).toBe(false);
   });
 
+  it("supports the sheet exactly for kinds with a compact sheet rule", () => {
+    expect(panelSupportsHost("file", "sheet")).toBe(true);
+    expect(panelSupportsHost("agent", "sheet")).toBe(true);
+    expect(panelSupportsHost("provider_subagent", "sheet")).toBe(true);
+    expect(panelSupportsHost("terminal", "sheet")).toBe(false);
+    expect(panelSupportsHost("plugin", "sheet")).toBe(false);
+  });
+
   it("lets navigation tabs hide their close button without losing their close action", () => {
     expect(getPanelManifest("files").showCloseButton).toBe(false);
     expect(getPanelManifest("changes_tree").showCloseButton).toBe(false);

packages/app/src/panels/panel-manifest.ts

@@ -1,12 +1,38 @@
 import type { WorkspaceTabTarget } from "@/workspace-tabs/model";
 
-export type PaneHost = "main" | "explorer";
+/** Where a tab renders: a split pane, the Explorer dock, or the compact workspace sheet. */
+export type PaneHost = "main" | "explorer" | "sheet";
+
+/** How a target behaves while it is shown in the compact workspace sheet. */
+export interface CompactSheetPolicy {
+  /** The sheet offers Open as tab, which moves the same tab into the focused pane. */
+  openAsTab: boolean;
+}
+
+/** Facts about a target that live outside the layout, resolved lazily by the workspace. */
+export interface PanelTargetFacts {
+  isWorkspaceRootAgent(agentId: string): boolean;
+}
+
+type CompactSheetRule<K extends WorkspaceTabTarget["kind"]> =
+  | CompactSheetPolicy
+  | null
+  | ((
+      target: Extract<WorkspaceTabTarget, { kind: K }>,
+      facts: PanelTargetFacts,
+    ) => CompactSheetPolicy | null);
 
 export interface PanelManifest<K extends WorkspaceTabTarget["kind"] = WorkspaceTabTarget["kind"]> {
   kind: K;
-  supportedHosts: readonly PaneHost[];
+  /** The sheet is never listed: a kind renders there exactly when it has a `compactSheet` rule. */
+  supportedHosts: readonly Exclude<PaneHost, "sheet">[];
   showCloseButton: boolean;
   singleton: boolean;
+  /**
+   * On compact layouts, revealing this target opens it in the workspace sheet over the current
+   * tab instead of adding a tab. `null` keeps it in the tab strip.
+   */
+  compactSheet: CompactSheetRule<K>;
   resourceKey(target: Extract<WorkspaceTabTarget, { kind: K }>): string;
 }
 
@@ -20,6 +46,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: () => "new_tab",
   },
   draft: {
@@ -27,6 +54,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: (target) => target.draftId,
   },
   agent: {
@@ -34,6 +62,8 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: (target, facts) =>
+      facts.isWorkspaceRootAgent(target.agentId) ? null : { openAsTab: true },
     resourceKey: (target) => target.agentId,
   },
   provider_subagent: {
@@ -41,6 +71,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: { openAsTab: false },
     resourceKey: (target) => `${target.parentAgentId}:${target.subagentId}`,
   },
   terminal: {
@@ -48,6 +79,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: (target) => target.terminalId,
   },
   browser: {
@@ -55,6 +87,7 @@ const manifests = {
     supportedHosts: ["main"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: (target) => target.browserId,
   },
   changes_tree: {
@@ -62,6 +95,7 @@ const manifests = {
     supportedHosts: ["explorer"],
     showCloseButton: false,
     singleton: true,
+    compactSheet: null,
     resourceKey: () => "changes_tree",
   },
   files: {
@@ -69,6 +103,7 @@ const manifests = {
     supportedHosts: ["explorer"],
     showCloseButton: false,
     singleton: true,
+    compactSheet: null,
     resourceKey: () => "files",
   },
   pull_request: {
@@ -76,6 +111,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: () => "pull_request",
   },
   file: {
@@ -83,6 +119,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: { openAsTab: false },
     resourceKey: (target) => target.path,
   },
   working_diff: {
@@ -90,6 +127,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: () => "working_diff",
   },
   plugin: {
@@ -98,6 +136,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: (target) =>
       target.context === "agent"
         ? `${target.pluginId}:${target.panelId}:agent:${target.agentId}`
@@ -108,6 +147,7 @@ const manifests = {
     supportedHosts: ["main"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: (target) => target.workspaceId,
   },
   commit_diff: {
@@ -115,6 +155,7 @@ const manifests = {
     supportedHosts: ["main", "explorer"],
     showCloseButton: true,
     singleton: false,
+    compactSheet: null,
     resourceKey: (target) => target.sha,
   },
 } satisfies PanelManifestByKind;
@@ -124,7 +165,17 @@ export function getPanelManifest<K extends WorkspaceTabTarget["kind"]>(kind: K):
 }
 
 export function panelSupportsHost(kind: WorkspaceTabTarget["kind"], host: PaneHost): boolean {
-  return getPanelManifest(kind).supportedHosts.includes(host);
+  const manifest = getPanelManifest(kind);
+  if (host === "sheet") return manifest.compactSheet !== null;
+  return manifest.supportedHosts.includes(host);
+}
+
+export function panelCompactSheetPolicy(
+  target: WorkspaceTabTarget,
+  facts: PanelTargetFacts,
+): CompactSheetPolicy | null {
+  const rule = getPanelManifest(target.kind).compactSheet as CompactSheetRule<typeof target.kind>;
+  return typeof rule === "function" ? rule(target as never, facts) : rule;
 }
 
 export function panelCanLaunchInPane(

packages/app/src/plugins/workspace-panels/locations.ts

@@ -50,7 +50,7 @@ export function panelTargetSupportsHost(
   target: WorkspaceTabTarget,
   host: PaneHost,
 ): boolean {
-  if (target.kind !== "plugin") return panelSupportsHost(target.kind, host);
+  if (target.kind !== "plugin" || host === "sheet") return panelSupportsHost(target.kind, host);
   const panel = findPluginPanel(serverId, target);
   // Preserve a persisted unavailable panel where the user left it until its plugin loads again.
   if (!panel) return true;

packages/app/src/provider-selection/provider-selection.test.ts

@@ -9,6 +9,7 @@ import {
   buildSelectedTriggerLabel,
   filterAndRankModelRows,
   matchesModelSearch,
+  resolveEffectiveComposerModeId,
   resolveSelectedModelLabel,
   resolveSubmissionReadiness,
 } from "./provider-selection";
@@ -441,3 +442,56 @@ function getAllModelLabels(providers: ReturnType<typeof buildSelectableProviderS
       : [],
   );
 }
+
+describe("resolveEffectiveComposerModeId", () => {
+  const selection = {
+    provider: "pi",
+    modelId: "",
+    thinkingOptionId: "",
+    availableModels: [],
+  };
+
+  it("drops a remembered mode when the provider offers no modes", () => {
+    expect(
+      resolveEffectiveComposerModeId({ ...selection, modeId: "build", modeOptions: [] }, false),
+    ).toBe("");
+  });
+
+  it("submits the mode the picker shows when the remembered mode is not offered", () => {
+    expect(
+      resolveEffectiveComposerModeId(
+        {
+          ...selection,
+          modeId: "plan",
+          modeOptions: [
+            { id: "build", label: "Build" },
+            { id: "ask", label: "Ask" },
+          ],
+        },
+        false,
+      ),
+    ).toBe("build");
+  });
+
+  it("keeps a selected mode the provider offers", () => {
+    expect(
+      resolveEffectiveComposerModeId(
+        {
+          ...selection,
+          modeId: "ask",
+          modeOptions: [
+            { id: "build", label: "Build" },
+            { id: "ask", label: "Ask" },
+          ],
+        },
+        false,
+      ),
+    ).toBe("ask");
+  });
+
+  it("keeps the selected mode while the provider's modes are still loading", () => {
+    expect(
+      resolveEffectiveComposerModeId({ ...selection, modeId: "build", modeOptions: [] }, true),
+    ).toBe("build");
+  });
+});

packages/app/src/provider-selection/provider-selection.ts

@@ -272,6 +272,23 @@ export function resolveEffectiveComposerModelId(selection: ProviderSelectionStat
   );
 }
 
+// The mode picker shows the first offered mode when the selected one isn't
+// offered (e.g. a remembered mode the provider no longer advertises), so the
+// submitted mode must match that display. A provider with no modes gets none.
+// While the provider is still loading its modes aren't known yet, so the
+// selected mode is kept.
+export function resolveEffectiveComposerModeId(
+  selection: ProviderSelectionState,
+  isModelLoading: boolean,
+): string {
+  const selectedModeId = selection.modeId.trim();
+  if (isModelLoading) {
+    return selectedModeId;
+  }
+  const modeIds = selection.modeOptions.map((mode) => mode.id);
+  return modeIds.includes(selectedModeId) ? selectedModeId : (modeIds[0] ?? "");
+}
+
 export function resolveEffectiveComposerThinkingOptionId(
   selection: ProviderSelectionState,
   effectiveModelId: string,

packages/app/src/screens/new-workspace-screen.tsx

@@ -17,6 +17,7 @@ import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { ChevronDown, Folder, FolderPlus, GitBranch, GitPullRequest } from "lucide-react-native";
 import { Composer } from "@/composer";
 import { ComposerDock } from "@/composer/dock";
+import { useComposerEditingSession, useComposerFullscreen } from "@/composer/editing-session";
 import { FileDropZone } from "@/components/file-drop/file-drop-zone";
 import {
   resolveComposerAttachmentSubmitFormat,
@@ -891,7 +892,7 @@ function buildWorkspaceDraftSetupFromComposer(input: {
   return {
     provider: input.provider,
     cwd: input.cwd,
-    modeId: input.composerState.selectedMode || null,
+    modeId: input.composerState.effectiveModeId || null,
     model: input.composerState.effectiveModelId || null,
     thinkingOptionId: input.composerState.effectiveThinkingOptionId || null,
     featureValues: input.composerState.featureValues ?? {},
@@ -971,7 +972,7 @@ async function createWorkspaceChatAgent(input: CreateChatAgentInput): Promise<Su
     config: {
       provider,
       cwd,
-      modeId: composerState.selectedMode || undefined,
+      modeId: composerState.effectiveModeId || undefined,
       model: composerState.effectiveModelId || undefined,
       thinkingOptionId: composerState.effectiveThinkingOptionId || undefined,
       featureValues: composerState.featureValues,
@@ -1094,7 +1095,7 @@ function resolveWorkspaceDraftSubmissionConfig(input: {
   return {
     cwd: workspaceDirectory,
     provider,
-    modeId: composerState.selectedMode || null,
+    modeId: composerState.effectiveModeId || null,
     model: composerState.effectiveModelId || null,
     thinkingOptionId: composerState.effectiveThinkingOptionId || null,
     featureValues: composerState.featureValues,
@@ -1636,6 +1637,8 @@ export function NewWorkspaceScreen({
   const { t } = useTranslation();
   const isCompact = useIsCompactFormFactor();
   const toast = useToast();
+  const composerEditing = useNewWorkspaceComposerEditing();
+  const { leaveFullscreen } = composerEditing;
   const mergeWorkspaces = useCallback(
     (targetServerId: string, workspaces: Iterable<WorkspaceDescriptor>) => {
       getHostRuntimeStore().acceptWorkspaceSnapshots(targetServerId, Array.from(workspaces));
@@ -2121,6 +2124,7 @@ export function NewWorkspaceScreen({
                 return;
               }
               outcome = "navigated";
+              leaveFullscreen();
               navigateToWorkspace({ serverId: targetServerId, workspaceId });
             },
           });
@@ -2171,6 +2175,7 @@ export function NewWorkspaceScreen({
       forkDraftSetup,
       isStillOnCreateScreen,
       launchTarget,
+      leaveFullscreen,
       selectedServerId,
       supportsForgeSearch,
       t,
@@ -2227,6 +2232,7 @@ export function NewWorkspaceScreen({
             return;
           }
           outcome = "navigated";
+          leaveFullscreen();
           navigateToWorkspace({ serverId: targetServerId, workspaceId, target });
         },
       });
@@ -2250,6 +2256,7 @@ export function NewWorkspaceScreen({
     t,
     terminalPromptText,
     toast,
+    leaveFullscreen,
     updateFormPreferences,
     withConnectedClient,
   ]);
@@ -2369,10 +2376,12 @@ export function NewWorkspaceScreen({
 
   const importSession = useImportSession({ serverId: selectedServerId });
 
+  const isComposerFullscreen = composerEditing.isFullscreen(isTerminalLaunch);
   const composer = isTerminalLaunch ? (
     <Composer
       key="terminal"
       inputMode="terminal"
+      editingSession={composerEditing.terminal}
       readOnly={!terminalTakesPrompt}
       placeholder={terminalPlaceholder}
       submitLabel={terminalSubmitLabel}
@@ -2399,6 +2408,7 @@ export function NewWorkspaceScreen({
   ) : (
     <Composer
       key="chat"
+      editingSession={composerEditing.chat}
       agentId={draftKey}
       serverId={selectedServerId}
       isPaneFocused={true}
@@ -2429,32 +2439,53 @@ export function NewWorkspaceScreen({
   );
   return (
     <FileDropZone style={styles.container}>
-      <MenuHeader borderless />
-      <View style={styles.content}>
-        <TitlebarDragRegion />
-        <NewWorkspaceLayout
-          isCompact={isCompact}
-          title={t("newWorkspace.title")}
-          formStack={formStack}
-          onImportSession={importSession.open}
-        >
-          {composer}
-          {errorMessage ? <Text style={styles.errorText}>{errorMessage}</Text> : null}
-        </NewWorkspaceLayout>
-      </View>
+      <NewWorkspaceLayout
+        isCompact={isCompact}
+        fullscreen={isComposerFullscreen}
+        title={t("newWorkspace.title")}
+        formStack={formStack}
+        onImportSession={importSession.open}
+      >
+        {composer}
+        {errorMessage ? <Text style={styles.errorText}>{errorMessage}</Text> : null}
+      </NewWorkspaceLayout>
       {importSession.sheet}
     </FileDropZone>
   );
 }
 
+/** Terminal and chat launches edit in separate sessions; the screen follows the mounted one. */
+function useNewWorkspaceComposerEditing() {
+  const terminal = useComposerEditingSession("terminal");
+  const chat = useComposerEditingSession("chat");
+  const isTerminalFullscreen = useComposerFullscreen(terminal);
+  const isChatFullscreen = useComposerFullscreen(chat);
+  // The sessions outlive the screen (its draft keeps them), so a launch that leaves
+  // the screen also leaves fullscreen; the next draft starts inline.
+  const leaveFullscreen = useCallback(() => {
+    terminal.setFullscreen(false);
+    chat.setFullscreen(false);
+  }, [chat, terminal]);
+  return {
+    terminal,
+    chat,
+    leaveFullscreen,
+    isFullscreen: (isTerminalLaunch: boolean) =>
+      isTerminalLaunch ? isTerminalFullscreen : isChatFullscreen,
+  };
+}
+
 function NewWorkspaceLayout({
   isCompact,
+  fullscreen,
   title,
   formStack,
   onImportSession,
   children,
 }: {
   isCompact: boolean;
+  /** The composer covers the screen; the header leaves and the dock fills the content. */
+  fullscreen: boolean;
   title: string;
   formStack: ReactNode;
   onImportSession: () => void;
@@ -2472,13 +2503,19 @@ function NewWorkspaceLayout({
     </>
   );
   return (
-    <ComposerDock centered={!isCompact}>
-      {setupFields}
-      <>
-        {children}
-        {isCompact ? null : importSessionButton}
-      </>
-    </ComposerDock>
+    <>
+      {fullscreen ? null : <MenuHeader borderless />}
+      <View style={styles.content}>
+        <TitlebarDragRegion />
+        <ComposerDock centered={!isCompact} fullscreen={fullscreen}>
+          {setupFields}
+          <>
+            {children}
+            {isCompact || fullscreen ? null : importSessionButton}
+          </>
+        </ComposerDock>
+      </View>
+    </>
   );
 }
 

packages/app/src/screens/settings/appearance/appearance-section.tsx

@@ -241,7 +241,7 @@ interface FontFamilyRowProps {
   draft: string;
   withBorder: boolean;
   onChangeDraft: (value: string) => void;
-  onCommit: (value: string) => void;
+  onCommit: (value: string) => string;
 }
 
 function FontFamilyRow({
@@ -255,13 +255,16 @@ function FontFamilyRow({
   onChangeDraft,
   onCommit,
 }: FontFamilyRowProps) {
+  const inputRef = useRef<EditingTextInputHandle>(null);
   const handleCommit = useCallback(() => {
-    onCommit(draft);
+    const committed = onCommit(draft);
+    inputRef.current?.replaceText(committed);
   }, [draft, onCommit]);
 
   // Resync from the committed value when it changes elsewhere.
   useEffect(() => {
     onChangeDraft(value);
+    inputRef.current?.replaceText(value);
     // Only resync on external value changes, not on local keystrokes.
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [value]);
@@ -273,6 +276,7 @@ function FontFamilyRow({
         <Text style={settingsStyles.rowHint}>{hint}</Text>
       </View>
       <TextInput
+        ref={inputRef}
         initialValue={draft}
         onChangeText={onChangeDraft}
         onBlur={handleCommit}
@@ -533,12 +537,13 @@ export function AppearanceSection() {
       const sanitized = sanitizeFontFamily(value);
       if (sanitized === null) {
         setUiFontDraft(settings.uiFontFamily);
-        return;
+        return settings.uiFontFamily;
       }
       setUiFontDraft(sanitized);
       if (sanitized !== settings.uiFontFamily) {
         void updateSettings({ uiFontFamily: sanitized });
       }
+      return sanitized;
     },
     [settings.uiFontFamily, updateSettings],
   );
@@ -548,12 +553,13 @@ export function AppearanceSection() {
       const sanitized = sanitizeFontFamily(value);
       if (sanitized === null) {
         setMonoFontDraft(settings.monoFontFamily);
-        return;
+        return settings.monoFontFamily;
       }
       setMonoFontDraft(sanitized);
       if (sanitized !== settings.monoFontFamily) {
         void updateSettings({ monoFontFamily: sanitized });
       }
+      return sanitized;
     },
     [settings.monoFontFamily, updateSettings],
   );

packages/app/src/screens/settings/plugins-page.test.tsx

@@ -80,6 +80,7 @@ vi.mock("@gorhom/bottom-sheet", async () => {
     await vi.importActual<typeof import("react-native")>("react-native");
   return {
     BottomSheetBackdrop: () => null,
+    BottomSheetHandle: () => null,
     BottomSheetModal: ReactModule.forwardRef(() => null),
     BottomSheetScrollView: ScrollView,
     BottomSheetTextInput: TextInput,

packages/app/src/screens/workspace/visible-agent-ids.test.ts

@@ -110,3 +110,25 @@ test("pane retargeting replaces the viewed agent and duplicate panes collapse to
     }),
   }).toEqual({ duplicate: ["agent-a"], retargeted: ["agent-a", "agent-b"] });
 });
+
+test("the agent shown in the workspace sheet is viewed alongside the pane under it", () => {
+  const layout: WorkspaceLayout = {
+    focusedPaneId: "main",
+    root: { kind: "pane", pane: { id: "main", tabIds: ["a"], focusedTabId: "a" } },
+  };
+  const tabs: WorkspaceTab[] = [
+    { tabId: "a", target: { kind: "agent", agentId: "agent-a" }, createdAt: 1 },
+  ];
+  const sheetTab: WorkspaceTab = {
+    tabId: "sheet",
+    target: { kind: "agent", agentId: "agent-child" },
+    createdAt: 2,
+  };
+
+  expect(
+    selectVisibleAgentIds({ layout, tabs, sheetTab, routeFocused: true, focusedPaneOnly: true }),
+  ).toEqual(["agent-a", "agent-child"]);
+  expect(
+    selectVisibleAgentIds({ layout, tabs, sheetTab, routeFocused: false, focusedPaneOnly: true }),
+  ).toEqual([]);
+});

packages/app/src/screens/workspace/visible-agent-ids.ts

@@ -6,6 +6,8 @@ import { deriveWorkspacePaneState } from "./workspace-pane-state";
 export function selectVisibleAgentIds(input: {
   layout: WorkspaceLayout | null;
   tabs: WorkspaceTab[];
+  /** The workspace sheet's tab, shown over the panes. */
+  sheetTab?: WorkspaceTab | null;
   routeFocused: boolean;
   focusedPaneOnly: boolean;
 }): string[] {
@@ -16,20 +18,21 @@ export function selectVisibleAgentIds(input: {
     ? collectAllPanes(input.layout.root).filter((pane) => pane.id === input.layout?.focusedPaneId)
     : collectAllPanes(input.layout.root);
 
+  const targets = panes.flatMap((pane) => {
+    const target = deriveWorkspacePaneState({ pane, tabs: input.tabs }).activeTab?.descriptor
+      .target;
+    return target ? [target] : [];
+  });
+  if (input.sheetTab) targets.push(input.sheetTab.target);
   return [
-    ...new Set(
-      panes.flatMap((pane) => {
-        const target = deriveWorkspacePaneState({ pane, tabs: input.tabs }).activeTab?.descriptor
-          .target;
-        return target?.kind === "agent" ? [target.agentId] : [];
-      }),
-    ),
+    ...new Set(targets.flatMap((target) => (target.kind === "agent" ? [target.agentId] : []))),
   ].sort();
 }
 
 export function useVisibleAgentIds(input: {
   layout: WorkspaceLayout | null;
   tabs: WorkspaceTab[];
+  sheetTab: WorkspaceTab | null;
   routeFocused: boolean;
   focusedPaneOnly: boolean;
 }): string[] {

packages/app/src/screens/workspace/workspace-screen.tsx

@@ -1,4 +1,7 @@
-import { WorkspaceComposerEditingSessionsProvider } from "@/composer/editing-session";
+import {
+  WorkspaceComposerEditingSessionsProvider,
+  useComposerTabFullscreen,
+} from "@/composer/editing-session";
 import { LoadingSpinner } from "@/components/ui/loading-spinner";
 import type { JsonValue } from "@getpaseo/protocol/agent-types";
 import { getOpenAgentTabLabel } from "@getpaseo/protocol/agent-labels";
@@ -73,7 +76,9 @@ import {
   getFocusedBrowserId,
   FOCUSED_PANE_PLACEMENT,
   selectExplorerSidebarPaneId,
+  selectPaneFocusSuspended,
   type WorkspaceLayout,
+  type WorkspaceSheet,
   type WorkspaceTabPlacement,
   useWorkspaceLayoutStore,
   useWorkspaceLayoutStoreHydrated,
@@ -160,6 +165,8 @@ import {
   type WorkspacePaneContentModel,
 } from "@/screens/workspace/workspace-pane-content";
 import { useMountedTabSet } from "@/screens/workspace/use-mounted-tab-set";
+import { WorkspaceSheetHost } from "@/screens/workspace/workspace-sheet-host";
+import type { PaneHost } from "@/panels/panel-manifest";
 import { WorkspaceFocusProvider } from "@/workspace/focus";
 import { DiffDocumentWorkspaceCacheProvider } from "@/git/diff-document/workspace-cache";
 import type { NewTabSelection } from "@/workspace-tabs/new-tab";
@@ -201,6 +208,7 @@ import { RenderProfile } from "@/utils/render-profiler";
 import { useWorkspaceCheckoutStatus } from "@/screens/workspace/use-workspace-checkout-status";
 import { useHasPullRequest, usePullRequestAutoAdd } from "@/panels/pull-request";
 
+const NO_SHEETS: readonly WorkspaceSheet[] = [];
 const WORKSPACE_FLOATING_PANEL_PORTAL_HOST_PREFIX = "workspace-floating-panels";
 const EMPTY_UI_TABS: WorkspaceTab[] = [];
 const EMPTY_WORKSPACE_SCRIPTS: WorkspaceDescriptor["scripts"] = [];
@@ -751,22 +759,20 @@ function WorkspaceContentProviders({
   );
 }
 
-function WorkspacePanelContent({
+function WorkspacePanelProviders({
   launcher,
-  content,
+  children,
   tabIds,
   workspaceKey,
 }: {
   workspaceKey: string;
   launcher: NewTabLauncher;
-  content: ReactNode;
+  children: ReactNode;
   tabIds: readonly string[];
 }) {
   return (
     <WorkspaceComposerEditingSessionsProvider workspaceKey={workspaceKey} tabIds={tabIds}>
-      <NewTabLauncherProvider value={launcher}>
-        <View style={styles.content}>{content}</View>
-      </NewTabLauncherProvider>
+      <NewTabLauncherProvider value={launcher}>{children}</NewTabLauncherProvider>
     </WorkspaceComposerEditingSessionsProvider>
   );
 }
@@ -823,6 +829,16 @@ function floatsHeaderOverContent(activeTab: WorkspaceTabDescriptor | null): bool
   return supportsStreamTopOverlay && activeTab?.kind === "agent";
 }
 
+/** A fullscreen composer covers the compact header; the column lays out without it. */
+function resolveCompactHeaderLayout(input: {
+  header: ReactNode;
+  activeTab: WorkspaceTabDescriptor | null;
+  composerFullscreen: boolean;
+}): { header: ReactNode; floating: boolean } {
+  if (input.composerFullscreen) return { header: null, floating: false };
+  return { header: input.header, floating: floatsHeaderOverContent(input.activeTab) };
+}
+
 function shouldShowWorkspaceScreenHeader(input: {
   isFocusModeEnabled: boolean;
   isMobile: boolean;
@@ -1267,6 +1283,9 @@ function WorkspaceScreenContent({
   const explorerSidebarPaneId = useWorkspaceLayoutStore((state) =>
     persistenceKey ? selectExplorerSidebarPaneId(state, persistenceKey) : null,
   );
+  const paneFocusSuspended = useWorkspaceLayoutStore((state) =>
+    persistenceKey ? selectPaneFocusSuspended(state, persistenceKey) : false,
+  );
   const lastMainPaneRef = useLastMainPane({
     workspaceKey: persistenceKey,
     layout: workspaceLayout,
@@ -1305,6 +1324,13 @@ function WorkspaceScreenContent({
   const focusWorkspaceTab = useWorkspaceLayoutStore((state) => state.focusTab);
   const selectWorkspaceTabInPane = useWorkspaceLayoutStore((state) => state.selectTabInPane);
   const closeWorkspaceTab = useWorkspaceLayoutStore((state) => state.closeTab);
+  const sheets = useWorkspaceLayoutStore((state) =>
+    persistenceKey ? (state.sheetsByWorkspace[persistenceKey] ?? NO_SHEETS) : NO_SHEETS,
+  );
+  // Only the top sheet is on screen.
+  const sheetTab = useWorkspaceLayoutStore((state) =>
+    persistenceKey ? (state.sheetsByWorkspace[persistenceKey]?.at(-1)?.tab ?? null) : null,
+  );
   const unpinWorkspaceAgent = useWorkspaceLayoutStore((state) => state.unpinAgent);
   const hideWorkspaceAgent = useWorkspaceLayoutStore((state) => state.hideAgent);
   const setWorkspaceTabState = useWorkspaceLayoutStore((state) => state.setTabState);
@@ -1377,6 +1403,7 @@ function WorkspaceScreenContent({
   const visibleAgentIds = useVisibleAgentIds({
     layout: workspaceLayout,
     tabs: uiTabs,
+    sheetTab,
     routeFocused: isRouteFocused,
     focusedPaneOnly: syncFocusedPaneOnly,
   });
@@ -1678,7 +1705,6 @@ function WorkspaceScreenContent({
       }
 
       const tabId = openPreferredWorkspaceTarget({
-        isCompact: isMobile,
         workspaceKey: persistenceKey,
         target: createWorkspaceFileTabTarget(location),
         source: "chatFiles",
@@ -2062,6 +2088,12 @@ function WorkspaceScreenContent({
 
   const handleCloseTabById = useCallback(
     async (tabId: string) => {
+      if (persistenceKey && sheets.some((sheet) => sheet.tab.tabId === tabId)) {
+        if (await confirmDiscardModifiedTab(tabId)) {
+          closeWorkspaceTab(persistenceKey, tabId);
+        }
+        return;
+      }
       const tab = allTabDescriptorsById.get(tabId);
       if (!tab) {
         return;
@@ -2081,10 +2113,13 @@ function WorkspaceScreenContent({
     },
     [
       allTabDescriptorsById,
+      closeWorkspaceTab,
       confirmDiscardModifiedTab,
       handleCloseAgentTab,
       handleClosePassiveTab,
       handleCloseTerminalTab,
+      persistenceKey,
+      sheets,
     ],
   );
 
@@ -2918,17 +2953,19 @@ function WorkspaceScreenContent({
       tab: WorkspaceTabDescriptor;
       paneId?: string | null;
       focusPaneBeforeOpen?: boolean;
+      host?: PaneHost;
     }) =>
       buildWorkspacePaneContentModel({
         tab: input.tab,
         normalizedServerId,
         normalizedWorkspaceId,
         host:
-          canRenderDesktopPaneSplits &&
+          input.host ??
+          (canRenderDesktopPaneSplits &&
           input.paneId !== null &&
           input.paneId === explorerSidebarPaneId
             ? "explorer"
-            : "main",
+            : "main"),
         fileNavigationRevision: fileNavigationRevisionByTabId[input.tab.tabId] ?? 0,
         onOpenTab: (target) => {
           if (!persistenceKey) {
@@ -2947,7 +2984,6 @@ function WorkspaceScreenContent({
         onOpenPreferredTarget: (target, source) => {
           if (!persistenceKey) return;
           const tabId = openPreferredWorkspacePreview({
-            isCompact: isMobile,
             workspaceKey: persistenceKey,
             serverId: normalizedServerId,
             workspaceId: normalizedWorkspaceId,
@@ -3009,7 +3045,6 @@ function WorkspaceScreenContent({
       canRenderDesktopPaneSplits,
       openImportSheet,
       openInSidePane,
-      isMobile,
       requestFileNavigation,
       revealWorkspaceChildTab,
       persistenceKey,
@@ -3053,6 +3088,17 @@ function WorkspaceScreenContent({
     },
     [buildPaneContentModel],
   );
+  const buildSheetPaneContentModel = useCallback(
+    function buildSheetPaneContentModel(tab: WorkspaceTabDescriptor) {
+      return buildPaneContentModel({
+        tab,
+        paneId: null,
+        focusPaneBeforeOpen: false,
+        host: "sheet",
+      });
+    },
+    [buildPaneContentModel],
+  );
   const handleFocusPane = useStableEvent(function handleFocusPane(paneId: string) {
     if (!persistenceKey || paneFocusSuppressedRef.current) {
       return;
@@ -3068,7 +3114,7 @@ function WorkspaceScreenContent({
     focusedPaneTabDescriptorMap,
     isRouteFocused,
     focusedPaneId,
-    paneFocusSuspended: Boolean(unfocusedPaneId),
+    paneFocusSuspended,
     onFocusPane: handleFocusPane,
     buildMobilePaneContentModel,
   });
@@ -3495,28 +3541,47 @@ function WorkspaceScreenContent({
   const desktopContent = desktopSplitContent ?? content;
   const rendersDesktopSplitContent = !isMobile && desktopSplitContent !== null;
 
-  const workspacePanelContent = (
-    <WorkspacePanelContent
-      launcher={newTabLauncher}
-      workspaceKey={`${normalizedServerId}:${normalizedWorkspaceId}`}
-      tabIds={uiTabs.map((tab) => tab.tabId)}
-      content={isMobile ? content : desktopContent}
-    />
+  const workspacePanelTabIds = useMemo(
+    () => [...uiTabs.map((tab) => tab.tabId), ...sheets.map((sheet) => sheet.tab.tabId)],
+    [uiTabs, sheets],
   );
+  const workspacePanelKey = `${normalizedServerId}:${normalizedWorkspaceId}`;
+  const compactHeaderLayout = resolveCompactHeaderLayout({
+    header: compactWorkspaceHeader,
+    activeTab: activeTabDescriptor,
+    composerFullscreen: useComposerTabFullscreen(workspacePanelKey, activeTabId),
+  });
 
+  // The sheet is the column's last child, so it covers the compact header as a modal.
   const workspaceCenterColumn = isMobile ? (
-    <View style={styles.centerColumn}>
-      <FloatingHeaderLayout
-        header={compactWorkspaceHeader}
-        floating={floatsHeaderOverContent(activeTabDescriptor)}
-      >
-        {(topOverlayInset) => (
-          <StreamTopOverlayProvider value={topOverlayInset}>
-            {workspacePanelContent}
-          </StreamTopOverlayProvider>
-        )}
-      </FloatingHeaderLayout>
-    </View>
+    <WorkspacePanelProviders
+      launcher={newTabLauncher}
+      workspaceKey={workspacePanelKey}
+      tabIds={workspacePanelTabIds}
+    >
+      <View style={styles.centerColumn}>
+        <FloatingHeaderLayout
+          header={compactHeaderLayout.header}
+          floating={compactHeaderLayout.floating}
+        >
+          {(topOverlayInset) => (
+            <StreamTopOverlayProvider value={topOverlayInset}>
+              <View style={styles.content}>{content}</View>
+            </StreamTopOverlayProvider>
+          )}
+        </FloatingHeaderLayout>
+        <StreamTopOverlayProvider value={0}>
+          <WorkspaceSheetHost
+            workspaceKey={persistenceKey}
+            serverId={normalizedServerId}
+            workspaceId={normalizedWorkspaceId}
+            isWorkspaceFocused={isRouteFocused}
+            buildContent={buildSheetPaneContentModel}
+            onCloseTab={handleCloseTabById}
+          />
+        </StreamTopOverlayProvider>
+      </View>
+    </WorkspacePanelProviders>
   ) : (
     <View style={styles.centerColumn}>
       {rendersDesktopSplitContent ? null : renderWorkspaceScreenHeader()}
@@ -3549,7 +3614,15 @@ function WorkspaceScreenContent({
         </NewTabLauncherProvider>
       ) : null}
 
-      <View style={styles.centerContent}>{workspacePanelContent}</View>
+      <View style={styles.centerContent}>
+        <WorkspacePanelProviders
+          launcher={newTabLauncher}
+          workspaceKey={workspacePanelKey}
+          tabIds={workspacePanelTabIds}
+        >
+          <View style={styles.content}>{desktopContent}</View>
+        </WorkspacePanelProviders>
+      </View>
     </View>
   );