paseo/docs/architecture.md

Architecture

Paseo is a client-server system for monitoring and controlling local AI coding agents. The daemon runs on your machine, manages agent processes, and streams their output in real time over WebSocket. Clients (mobile app, CLI, desktop app) connect to the daemon to observe and interact with agents.

Your code never leaves your machine. Paseo is local-first.

System overview

┌─────────────┐    ┌─────────────┐    ┌─────────────┐
│  Mobile App  │    │     CLI     │    │ Desktop App │
│   (Expo)     │    │ (Commander) │    │ (Electron)  │
└──────┬───────┘    └──────┬──────┘    └──────┬──────┘
       │                   │                  │
       │    WebSocket      │    WebSocket     │    Managed subprocess
       │    (direct or     │    (direct)      │    + WebSocket
       │     via relay)    │                  │
       └───────────┬───────┴──────────────────┘
                   │
            ┌──────▼──────┐
            │   Daemon    │
            │  (Node.js)  │
            └──────┬──────┘
                   │
      ┌────────────┼────────────┬────────────┬────────────┐
      │            │            │            │            │
┌─────▼─────┐ ┌───▼────┐ ┌──────▼─────┐ ┌────▼─────┐ ┌────▼────┐
│  Claude   │ │ Codex  │ │  Copilot   │ │ OpenCode │ │   Pi    │
│  Agent    │ │ Agent  │ │   Agent    │ │  Agent   │ │ Agent   │
│  SDK      │ │ Server │ │    ACP     │ │          │ │         │
└───────────┘ └────────┘ └────────────┘ └──────────┘ └─────────┘

Components at a glance

• Daemon: Local server that spawns and manages agent processes and exposes the WebSocket API.
• App: Cross-platform Expo client for iOS, Android, web, and the shared UI used by desktop.
• CLI: Terminal interface for agent workflows that can also start and manage the daemon.
• Desktop app: Electron wrapper around the web app that bundles and auto-manages its own daemon.
• Relay: Optional encrypted bridge for remote access without opening ports directly.

Packages

packages/server — The daemon

The heart of Paseo. A Node.js process that:

• Listens for WebSocket connections from clients
• Manages agent lifecycle (create, run, stop, resume, archive)
• Streams agent output in real time via a timeline model
• Provides agent-to-agent tools through a transport-neutral tool catalog, with MCP as one adapter
• Optionally connects outbound to a relay for remote access
• Optionally serves the browser web client from the same HTTP server (self-hosting guide: public-docs/web-ui.md)

All paths are under packages/server/src/.

Project identity is daemon-global rather than session-owned. After registry bootstrap, the daemon's project Git observer keeps one non-recursive watch on each lexically equivalent active project root and listens only for the root .git entry, with a slow rescan as a missed-event fallback. It runs for empty projects and without connected clients, then fans metadata changes through the WebSocket server to capability-aware sessions. It deliberately does not use the broad recursive working-tree watcher or the per-session Git observer: those are checkout/status mechanisms and intentionally do not retain non-Git directories.

Key modules:

Module	Responsibility
server/bootstrap.ts	Daemon initialization: HTTP server, WS server, agent manager, storage, relay
server/websocket-server.ts	WebSocket connection management, hello handshake, binary frame routing
server/session.ts	Per-client session state, timeline subscriptions, terminal operations
server/agent/agent-manager.ts	Agent lifecycle state machine, timeline tracking, subscriber management
server/agent/agent-storage.ts	File-backed JSON persistence at $PASEO_HOME/agents/
server/agent/tools/	Transport-neutral catalog for workspaces, agents, permissions, and automation
server/agent/mcp-server.ts	Thin MCP adapter that registers the Paseo tool catalog with the MCP SDK
server/agent/providers/	Provider adapters (see "Agent providers" below)
server/relay-transport.ts	Outbound relay connection with E2E encryption
server/schedule/	Cron-based scheduled agents
server/loop-service.ts	Looping agent runs that retry until an exit condition
server/chat/	Chat rooms for agent-to-agent and human-to-agent messaging

packages/protocol — Wire schemas and shared protocol types

The source of truth for WebSocket messages, binary frame codecs, endpoint parsing, agent timeline types, provider config schemas, and other values shared by daemon and clients. Server, app, CLI, and @getpaseo/client all depend on this package; it does not depend on the server.

packages/client — Daemon client library and SDK facade

Owns the low-level daemon WebSocket driver plus the higher-level PaseoClient facade. App and CLI may import the low-level driver from @getpaseo/client/internal/daemon-client during migration, while new SDK-shaped code imports from @getpaseo/client.

packages/app — Mobile + web client (Expo)

Cross-platform React Native app that connects to one or more daemons.

• Expo Router navigation (/h/[serverId]/workspace/[workspaceId], /h/[serverId]/agent/[agentId], etc.). The workspaceId URL segment is an opaque workspace id, not a directly meaningful filesystem path.
• HostRuntimeController manages saved host connections, reconnection, and per-host runtime state
• runtime/replica-cache keeps a non-authoritative per-host display replica in AsyncStorage: only the last focused agent, its workspace, and a short timeline tail. It restores before navigation becomes ready, leaves remote hydration flags false, and is atomically replaced by the normal snapshot-plus-delta synchronization path.
• SessionContext wraps the daemon client for the active session
• Composer UI and submit/draft behavior live in packages/app/src/composer/; screens and panels should integrate it from there instead of dropping composer internals into components/, hooks/, or screens/workspace/
• Timeline reducers in timeline/session-stream-reducers.ts handle compaction, gap detection, sequence-based deduplication
• Timeline sync correctness is documented in docs/timeline-sync.md: live streams are for immediacy, fetch_agent_timeline_request is authoritative, and catch-up is paged but complete.
• Voice features: dictation (STT) and voice agent (realtime)

The replica cache exists only to paint stale data immediately while the host connects. It does not own mutations, infer deletions, or replace daemon reconciliation. Pending permission requests are not restored from it. AsyncStorage is not encrypted, so the cached timeline tail may contain source code, prompts, and tool output; encrypted-at-rest storage is a separate product/security decision. Its serialized payload has a 1 MiB byte budget and evicts whole host snapshots in least-recently- written order; a single oversized host is omitted rather than partially restored.

packages/cli — Command-line client

Commander.js CLI with Docker-style commands. Common agent operations are also exposed at the top level (e.g. paseo ls, paseo run).

• paseo agent ls/run/import/attach/logs/stop/delete/send/inspect/wait/archive/reload/update/mode
• paseo daemon start/stop/restart/status/pair/set-password
• paseo chat ls/create/inspect/post/read/wait/delete
• paseo terminal ls/create/capture/send-keys/kill
• paseo script ls/start/stop
• paseo loop run/ls/inspect/logs/stop
• paseo schedule create/ls/inspect/update/pause/resume/run-once/logs/delete
• paseo heartbeat create/update/delete
• paseo workspace create/ls/archive
• paseo permit allow/deny/ls
• paseo provider ls/models
• hidden legacy paseo worktree create/ls/archive compatibility alias
• paseo speech …

Communicates with the daemon via the same WebSocket protocol as the app.

packages/relay — Relay transport and E2E encryption

Enables remote access when the daemon is behind a firewall.

• Curve25519 ECDH key exchange + XSalsa20-Poly1305 (NaCl box) encryption
• The relay is zero-knowledge — it routes encrypted bytes and cannot read content
• Client and daemon channels with identical API (createClientChannel, createDaemonChannel)
• Pairing via QR code transfers the daemon's public key to the client
• Optional E2EE capability negotiation preserves application frame kind: text plaintext uses base64 ciphertext text frames, while binary plaintext uses raw ciphertext binary frames; mixed-version peers remain base64-only
• Self-hosted relays opt into TLS with daemon.relay.useTls or PASEO_RELAY_USE_TLS=true; the public (client-facing) TLS setting can be overridden independently via daemon.relay.publicUseTls or PASEO_RELAY_PUBLIC_USE_TLS

The production relay server lives in getpaseo/paseo-relay. It is a distributed Elixir service. The Cloudflare relay implementation in this monorepo is retained as legacy code and is not deployed.

See SECURITY.md for the full threat model.

Paseo Hub

The optional Hub relationship is daemon-outbound and does not use the relay. Its connection, authorization, ownership, persistence, and lifecycle contract is documented in hub.md.

packages/desktop — Desktop app (Electron)

Electron wrapper for macOS, Linux, and Windows.

• Can spawn the daemon as a managed subprocess
• Native file access for workspace integration
• Same WebSocket client as mobile app

Multi-window (hybrid land-on model). createWindow() in main.ts is reusable: ⌘⇧N/File→New Window, relaunching the app (second-instance), and the sidebar "Open in new window" action each open a fresh BrowserWindow. Every window shows the full sidebar — there is no per-window project ownership or filtering. "Land on a project" is delivered by a per-webContents PendingOpenProjectStore: each window pulls its own pending project path on mount (paseo:get-pending-open-project) and runs the normal open-project flow, identical to a CLI paseo <path> launch.

Window-state v1 limitation: only the first window of a session restores and persists saved geometry (size/position/maximized). Windows opened via ⌘⇧N / second-instance / "Open in new window" open at the default size, OS-cascaded, and do not persist — this avoids every window stacking on the same restored bounds and fighting over the single window-state store. Lifting this needs per-window state keys.

In-app browser profile. Every browser guest uses one stable persistent Electron session, so cookies, authentication, cache, and site storage are shared across tabs, workspaces, and desktop windows and survive tab or app closure. Browser identity is independent of that storage partition: after every did-attach, the renderer explicitly registers its browser id, workspace id, and current guest WebContents id, and main accepts the registration only when that guest belongs to the calling renderer and the shared profile. Registration is intentionally repeated because reparenting a retained <webview> can replace its guest without replacing the DOM element. Settings > General > Clear browser data is the sole profile-deletion path; it clears the shared session and reloads live guests without deleting saved tabs or URLs.

In-app browser window opens. Ordinary link opens, including Shift-clicked links, become Paseo workspace tabs. Script-created opens with popup features or a named window target and POST-backed opens remain secured Electron child windows in the shared browser profile, preserving window.opener, postMessage, named-window reuse, request bodies, and window.close() for OAuth, payment, and similar popup protocols. Unsupported URL schemes are denied before either path.

In-app browser ownership. Each registered guest records its owning host window. The active browser is keyed by (host window, workspace), and application-menu Reload / Force Reload resolve only within the window Electron supplies to the menu callback. A non-null active update must name a browser owned by that host; a null update clears only that host/workspace. Browser automation continues to target explicit browser ids returned by browser_new_tab or browser_list_tabs.

Browser keyboard boundary. Guest pages receive renderer-published shortcuts first. Cmd/Ctrl+L and Cmd/Ctrl+R are explicit guest-shell reservations; ordinary Paseo shortcuts run only after the page declines them. The sandboxed guest preload runs in every frame so focused iframes use the same boundary, while Node integration remains disabled. Human guest input disables Electron's menu fallback for plain keys. Agent-generated keys use guest sendInputEvent with skipIfUnhandled, so an unhandled Enter stops at the guest instead of reaching the host composer. Main selects the preload; it exposes no APIs to guest pages.

Human key -> guest WebContents
  |-- Cmd/Ctrl+T/L/R ----------> reserved browser-shell action
  `-- page keydown
        |-- page prevents ------> page owns it
        `-- published shortcut -> guest preload -> IPC(browserId) -> Paseo resolver

Agent browser_keypress -> guest sendInputEvent(skipIfUnhandled)
  |-- guest handles ------------> page owns it
  `-- guest does not handle ----> stop; never redispatch to the host window

packages/website — Marketing site

TanStack Router + Cloudflare Workers. Serves paseo.sh.

WebSocket protocol

All clients speak the same WebSocket protocol over a single connection that mixes JSON text frames and a small binary framing for terminal streams. Schemas live in packages/protocol/src/messages.ts.

Handshake:

Client → Server:  WSHelloMessage {
                    type: "hello",
                    clientId,
                    clientType: "mobile" | "browser" | "cli" | "mcp",
                    protocolVersion,
                    appVersion?,
                    capabilities?: { voice?, pushNotifications?, ... },
                  }
Server → Client:  status message with payload { status: "server_info",
                    serverId, hostname, version, capabilities?, features }

There is no dedicated welcome message; the server emits a status session message after accepting the hello, then begins streaming. The session stores client capabilities from the hello and rehydrates them on reconnect, so the wire boundary can ask one question: session.supports(...).

Top-level WS envelopes are hello, recording_state, ping/pong, and session (which wraps the rich union of session messages).

Client liveness checks use the top-level JSON ping/pong envelope, not a session RPC or RFC6455 control ping. Current clients ping every 10 seconds, beginning one interval after connecting. The first ping claims an application-ownership lease for that physical socket, all later inbound activity renews it, and the daemon forcibly terminates the socket if the lease expires. A legacy or raw socket that never sends an application ping never enters this lease and is not closed for omitting one. Session RPC timeouts are operation failures and must not be treated as proof that the socket is dead.

Every physical send path enforces an 8 MiB outbound high-water mark, including JSON broadcasts, binary terminal frames, and the encrypted relay adapter's asynchronous queue. This sits above the terminal stream's 4 MiB soft backpressure threshold, leaving room for snapshot catch-up before the hard cutoff. JSON is serialized once per broadcast after sockets already at the limit are removed, then its exact byte length is checked for every remaining socket. A frame that would cross the limit is not sent; that physical socket is forcibly terminated without disturbing other sockets attached to the same logical session. Multiple tabs and simultaneous direct and relay paths may legitimately share a client id.

Client session RPC waits default to 60s so slow relay or mobile networks do not turn a live but delayed daemon response into a false operation failure. Keep connect timeouts, app-level grace windows, explicit diagnostic latency probes, liveness ping timers, and genuinely long-running RPCs separate from this default.

New session RPCs use dotted names with .request and .response suffixes, such as checkout.forge.set_auto_merge.request and checkout.forge.set_auto_merge.response. See rpc-namespacing.md for the convention and migration rules for older flat RPC names.

Notable session message types:

• agent_update — Agent state changed (status, title, labels)
• agent_stream — New timeline event from a running agent
• workspace_update, script_status_update, workspace_setup_progress — Workspace state
• agent_permission_request / agent_permission_resolved — Tool-call permission flow
• agent_deleted, agent_archived, agent_status, agent_list
• checkout_status_update, checkout_diff_update, and the full checkout_* request/response set for git operations
• Terminal subscribe/input/capture commands
• Voice/dictation streaming events (dictation_stream_*, assistant_chunk, audio_output, transcription_result)
• Request/response pairs for fetch, list, create, etc., correlated by requestId; failures use rpc_error

directory_suggestions_request is one daemon-owned filesystem search capability. The daemon configures the same searchDirectoryEntries engine with a root, output format, path-query policy, entry-kind filters, match mode, blank-query behavior, and hidden-directory traversal policy. A request without cwd searches the host home for absolute project paths; a request with cwd searches that workspace and returns relative entries. Clients may prepend their small host-scoped recent-project list for bare queries, but must not parse filesystem query syntax or re-filter a correlated daemon response. The legacy directories response field remains a projection of the typed entries list.

Binary frames (terminal stream protocol):

Terminal I/O is sent as binary WebSocket frames decoded by decodeTerminalStreamFrame in shared/binary-frames/terminal.ts. The layout is:

• 1-byte opcode: Output (0x01), Input (0x02), Resize (0x03), Snapshot (0x04)
• 1-byte slot: terminal slot id
• variable payload: bytes for output/input, JSON-encoded { rows, cols } for resize, terminal snapshot for snapshot

Terminal PTY size is last-interacting-client-wins. A client claims the PTY size only when its terminal viewport genuinely changes size or the user focuses/taps the terminal. Passive rendering work — attaching, restoring visibility, font settling, renderer refits, or just looking at a visible terminal — must not send a resize frame. The server does not broadcast resize ownership; the resized PTY redraws through normal output, and every attached client renders that output in its own local viewport.

There is also a separate file-transfer binary frame format in the same directory, used for download/upload streams. File downloads keep the existing FileBegin/FileChunk/FileEnd framing and stream 256 KiB chunks from one stable file handle. Each transfer awaits completion of its own physical WebSocket send before reading the next chunk; it is scoped to the requesting physical socket and does not queue unrelated messages or transfers.

Compatibility rules

• WebSocket schemas are append-only. Add fields, do not remove fields, and never make optional fields required.
• New wire enum values must be gated at serialization with session.supports(CLIENT_CAPS.someCapability).
• Session stores client capabilities from the hello handshake and rehydrates them on reconnect, so the wire boundary can ask one question: session.supports(...).

Example: adding a new enum value

// 1. Add CLIENT_CAPS.newThing = "new_thing"
// 2. Let new clients advertise it in WS hello
// 3. Keep the shared producer schema strict
// 4. Gate the new emitted value: session.supports(CLIENT_CAPS.newThing) ? "new_value" : "old_value"

Agent lifecycle

The lifecycle states are defined in shared/agent-lifecycle.ts:

initializing → idle ⇄ running
        ↓       ↓        ↓
              error
                ↓
              closed

• initializing — provider session is being created
• idle — has a live session, awaiting the next prompt
• running — provider is currently producing a turn
• error — last attempt failed; session is still attached
• closed — terminal state, no live session

ManagedAgent is a discriminated union over those lifecycle tags. Notes:

• AgentManager is the source of truth for agent state and broadcasts updates to all subscribers
• Timeline is append-only with epochs (each run starts a new epoch). Storage uses sequence numbers for client-side dedup; the default fetch page is 200 items
• Timeline row timestamp values are canonical daemon-owned timestamps. Providers may supply original replay timestamps, but clients must not guess timestamp trust or hide time UI based on local clock heuristics.
• Events stream to connected clients in real time; correctness is backed by authoritative timeline fetches and paged-to-completion catch-up.
• Agent state persists to $PASEO_HOME/agents/{cwd-with-dashes}/{agent-id}.json (timeline rows live alongside the record). That storage path is derived from cwd, not from workspace id.

Right-sidebar boundary: directory-backed vs workspace-owned

Two workspaces can share the same cwd (e.g. a directory workspace and a local_checkout workspace on the same folder, or several workspaces opened against one checkout). Model B keeps these distinct: they share everything the directory determines, but nothing the workspace owns. The right-sidebar surfaces split cleanly along this line, and the split is enforced purely by what each piece of state is keyed by.

Directory-backed (shared by same-cwd workspaces) — keyed by (serverId, cwd), never by workspaceId:

Surface	Key	Source
Git status	checkoutStatusQueryKey(serverId, cwd)	packages/app/src/git/query-keys.ts
Git diff	checkoutDiffQueryKey(serverId, cwd, mode, baseRef, ws)	packages/app/src/git/query-keys.ts
Forge change request	checkoutPrStatusQueryKey(serverId, cwd)	packages/app/src/git/query-keys.ts
Change request timeline	prPaneTimelineQueryKey({ serverId, cwd, prNumber })	packages/app/src/git/pull-request-panel/query-keys.ts
File preview content	["workspaceFile", serverId, cwd, path]	packages/app/src/components/file-pane.tsx
File explorer listings	fetched via listDirectory(workspaceRoot, path)	packages/app/src/hooks/use-file-explorer-actions.ts

Workspace-owned (independent per workspace) — keyed by workspaceId (falling back to cwd only when no workspaceId exists):

State	Key builder / store	Source
Review draft comments	buildReviewDraftKey / buildReviewDraftScopeKey	packages/app/src/review/store.ts
Diff mode override	review-draft scope key (in-memory)	packages/app/src/review/state.ts
Composer attachments	buildWorkspaceAttachmentScopeKey	packages/app/src/attachments/workspace-attachments-store.ts
File explorer nav/open state	fileExplorer map keyed workspace:{workspaceId}	packages/app/src/hooks/use-file-explorer-actions.ts
File explorer expanded paths	expandedPathsByWorkspace[workspaceStateKey]	packages/app/src/stores/panel-store/state.ts

diff-pane.tsx is the canonical wiring site: it passes { serverId, cwd } to the git queries and { serverId, workspaceId, cwd } to the draft/override/attachment scope keys.

Do not "fix" the sharing away. Re-keying a directory-backed query by workspaceId makes same-cwd workspaces diverge (two windows onto the same git tree showing different diffs). Re-keying owned state (drafts, expanded paths) by cwd makes them leak between distinct workspaces on the same folder. The workspaceId-keyed builders carry a // workspaceId is opaque; do not parse this key back into a path. comment — the opaque-id fallback to cwd exists only for old payloads without a workspaceId, not as a content-sharing mechanism.

One deliberate non-violation: AgentFileExplorerState.directories/files cache directory listings inside the workspaceId-keyed explorer map. Same-cwd workspaces therefore keep duplicate caches, but they can never diverge — both fetch the identical directory via listDirectory(workspaceRoot, …). This is duplication, not leakage, and is left as-is.

Agent providers

Each provider implements the AgentClient interface in agent/agent-sdk-types.ts. Provider implementations live in agent/providers/.

The built-in, user-facing providers are Claude Code, Codex, Copilot, OpenCode, Pi, and OMP. Additional adapters exist in the same directory for ACP-compatible agents and internal use:

Provider	Wraps	Session format
Claude (claude/)	Anthropic Agent SDK	~/.claude/projects/{cwd}/{session-id}.jsonl
Codex	Codex AppServer (codex-app-server)	~/.codex/sessions/{date}/rollout-{ts}-{id}.jsonl
Copilot	GitHub Copilot via ACP	Provider-managed
OpenCode	OpenCode server / CLI	Provider-managed
Cursor	ACP wrapper (acp-agent)	Provider-managed
Generic ACP	ACP wrapper	Provider-managed
Pi	Local Pi RPC process	Provider-managed
Mock load test	In-process fake	In-memory

All providers:

• Handle their own authentication (Paseo does not manage API keys)
• Support session resume via persistence handles
• Map tool calls to a normalized ToolCallDetail type
• Expose provider-specific modes (plan, default, full-access)

Providers that can accept native tool definitions should set supportsNativePaseoTools and read launchContext.paseoTools. The daemon then passes the shared Paseo tool catalog directly and removes the internal Paseo MCP server from that provider launch config. Providers that only support MCP continue to receive the same tools through the MCP fallback at /mcp/agents.

Data flow: running an agent

1. Client sends CreateAgentRequestMessage with config (prompt, cwd, provider, model, mode)
2. Session routes to AgentManager.create()
3. AgentManager creates a ManagedAgent, initializes provider session
4. Provider runs the agent → emits AgentStreamEvent items
5. Events append to the agent timeline, broadcast to all subscribed clients
6. Tool calls are normalized to ToolCallDetail (shell, read, edit, write, search, etc.)
7. Permission requests flow: agent → server → client → user decision → server → agent

Storage

$PASEO_HOME defaults to ~/.paseo. The most important files:

$PASEO_HOME/
├── agents/{cwd-with-dashes}/{agent-id}.json   # Agent record + persisted timeline rows
├── projects/projects.json                      # Project registry
├── projects/workspaces.json                    # Workspace registry
├── chat/                                       # Chat rooms
├── schedules/                                  # Scheduled-agent definitions and runs
├── loops/                                      # Loop runs and logs
├── config.json                                 # Daemon config (mutable)
├── daemon-keypair.json                         # Daemon identity for relay/E2EE
├── push-tokens.json                            # Mobile push tokens
├── paseo.sock / paseo.pid                      # Local IPC socket and pidfile
└── daemon.log                                  # Daemon trace logs (rotated)

Deployment models

1. Local daemon (default): paseo daemon start on 127.0.0.1:6767
2. Managed desktop: Electron app spawns daemon as subprocess, and stops it again on quit so that "restart the app" is a complete reset. Settings > Host > "Keep daemon running after quit" opts out. Only a daemon the desktop started is stopped — a daemon you started yourself with paseo daemon start is left alone (paseo.pid records desktopManaged).
3. Remote + relay: Daemon behind firewall, relay bridges with E2E encryption