[harshithmullapudi]

Summary

The host-service /events bus now sends chat:sessions-changed whenever a workspace's chat-v3 session listing changes. Remote clients such as Roster can refetch listSessions for that workspace when it arrives, instead of polling each host.

Message

{ type: "chat:sessions-changed"; workspaceId: string; occurredAt: number }

This is a nudge, like agent:bindings-changed and page-watch:changed. It carries no session state, so it cannot disagree with listSessions. The client refetches listSessions({ workspaceId }) for the current state.

When it fires

• The journal writes a change to a session row.
  • A session is created, or re-opened with a new epoch.
  • Its status, title or queued count changes.
  • It is discarded (harness start failed).
• closeSession stops a live agent. That changes liveness without a journal write, so closeSession reports it after disposal, even if disposal throws.

It does not fire on items, deltas, or session events that leave the listing unchanged.

A host restart sends nothing, because no client is connected while the host is down. A client refetches when its /events socket reconnects.

occurredAt on appends is the journal's own ts, so it matches the row's updatedAt.

Wiring

• ChatJournal takes onSessionChanged. createChatRuntime and createChatV3Mount pass it through, and app.ts maps it to EventBus.broadcastChatSessionsChanged.
• A listener that throws, or returns a promise that rejects, is caught and logged. A durable write never fails because of an observer.
• workspace-client routes the message by workspaceId and exports ChatSessionsChangedPayload ({ occurredAt }).
• Stored session status is now typed SessionStatus all the way through. On the column this is $type only, so there is no migration.

Compatibility

The change is additive. No tRPC procedure, input or output changed. Released clients drop message types they have no listener for. Hosts without this change never send the message, so clients should keep a listSessions fallback.

Test plan

• Live, against the real chat-v3 routes and EventBus with a real claude-acp agent. The run used an in-process host-service wired like app.ts, under Electron's Node, with chat-v3 called over HTTP:
  • createSession → nudge
  • starting → idle → nudge; listSessions returned idle
  • prompt → nudge on running, then nudge on idle; the agent replied OK
  • closeSession → one nudge; getSession.live became false
  • An earlier run hit a harness start failure. The status went to dead and that also sent a nudge.
• packages/chat-runtime: bun test --isolate: 193 pass. New tests cover listing-only changes, a throwing listener, and closeSession reporting once.
• packages/host-service: bun test --isolate src/events/event-bus.test.ts src/chat-v3: 26 pass.
• packages/workspace-client: bun test src/lib/eventBus.test.ts: 12 pass.
• Typecheck: chat-runtime and chat are clean. host-service and workspace-client show only the existing 22 auth/trpc errors.
• bunx biome check: clean.

Review follow-ups

• SDK removed from this PR, as asked. Roster calls the HTTP endpoints directly. Host chat calls through the relay work since fix(relay): forward HTTP to a host's chat-v3 tRPC endpoint #8159.
• open() uses openEpoch's minted instead of reading the row three times.
• occurredAt comes from the journal's ts.

---

Summary by cubic

Emits chat:sessions-changed on the host-service /events bus so remote clients like Roster stop polling listSessions per host. The SDK changes are not part of this PR.

The event is a workspace-wide nudge carrying only { workspaceId, occurredAt }; clients refetch listSessions for that workspace, so the event can never disagree with the listing.

• ChatJournal fires on session creation, re-open with a changed status, status/title/queued-count changes, and discard.
• closeSession announces once a live agent stops, since closing changes liveness without a journal write.
• A throwing onSessionChanged listener is caught and logged so it can't fail a committed append; stored status is typed SessionStatus end to end.
• workspace-client routes the event to listeners scoped by workspace or "*"; released clients ignore it and the listSessions fallback stays.
• setModel is left for a follow-up since the claude-code and codex adapters have no mid-session model-change path.

^{Written for commit e490168. Summary will update on new commits.}

Summary by CodeRabbit

• New Features
  • Chat session changes now trigger workspace-scoped notifications, so connected clients can refresh session lists when sessions are opened, updated, closed, or discarded.
• Bug Fixes
  • Closing a live session now notifies clients after shutdown, including when shutdown encounters an error. Repeated close requests do not send duplicate notifications.

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📒 Files selected for processing (12)

• packages/chat-runtime/src/commands/commands/commands.test.ts
• packages/chat-runtime/src/commands/commands/commands.ts
• packages/chat-runtime/src/journal/journal/journal.test.ts
• packages/chat-runtime/src/journal/journal/journal.ts
• packages/host-service/src/app.ts
• packages/host-service/src/events/event-bus.test.ts
• packages/host-service/src/events/event-bus.ts
• packages/host-service/src/events/index.ts
• packages/host-service/src/events/types.ts
• packages/workspace-client/src/index.ts
• packages/workspace-client/src/lib/eventBus.test.ts
• packages/workspace-client/src/lib/eventBus.ts

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---

📝 Walkthrough

Walkthrough

The chat journal reports session-listing changes through an optional callback. The host broadcasts these changes as workspace-scoped events, and the workspace client filters and dispatches them to matching listeners.

Changes

Chat session status events

Layer / File(s)	Summary
Journal change notifications packages/chat-runtime/src/db/schema/schema.ts, packages/chat-runtime/src/journal/epoch/epoch.ts, packages/chat-runtime/src/projection/projection.ts, packages/chat-runtime/src/journal/journal/journal.ts, packages/chat-runtime/src/journal/journal/journal.test.ts, packages/chat-runtime/src/index.ts, packages/chat-runtime/src/journal/index.ts, packages/chat-runtime/src/journal/journal/index.ts, packages/chat-runtime/src/commands/commands/commands.ts, packages/chat-runtime/src/commands/commands/commands.test.ts, packages/host-service/src/chat-v3/mount.ts	The journal adds an optional session-change callback. It notifies when opening creates an epoch, when session-listing fields change, when a session is discarded, or when a live session is announced. The runtime and chat mount forward the callback. Session status fields use SessionStatus, and tests cover notifications and listener failures.
Host event broadcast packages/host-service/src/events/types.ts, packages/host-service/src/events/index.ts, packages/host-service/src/events/event-bus.ts, packages/host-service/src/events/event-bus.test.ts, packages/host-service/src/app.ts	The host adds the chat:sessions-changed server message and broadcast method. The app connects journal notifications to the event bus, using the session scope as workspaceId and forwarding occurredAt.
Workspace-scoped client delivery packages/workspace-client/src/lib/eventBus.ts, packages/workspace-client/src/lib/eventBus.test.ts, packages/workspace-client/src/index.ts	The workspace client recognizes and dispatches chat:sessions-changed events to listeners for the matching workspace. The event payload includes occurredAt, and a test checks workspace filtering.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant ChatRuntime
  participant ChatJournal
  participant App
  participant EventBus
  participant WorkspaceClient
  ChatRuntime->>ChatJournal: Configure onSessionChanged
  ChatJournal->>App: Report sessionId, scopeId, and occurredAt
  App->>EventBus: Broadcast chat:sessions-changed with workspaceId and occurredAt
  EventBus->>WorkspaceClient: Send chat:sessions-changed

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Suggested reviewers: kitenite

Merge Risk: ⚪ Minimal · up to 3d9c6

Chat session changes now notify workspace listeners through the host event bus with a simple "refetch sessions" signal. Listener failures are logged without affecting saved data. No blocking issues remain in the notification flow.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 3d9c6

The change adds lightweight activity notifications within the existing host-access boundary. No new privilege or chat-content exposure was demonstrated. Access-policy and deployment coverage remains incomplete.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• observed — The new readable information is workspace activity metadata across every workspace on an authorized host. Every connected event socket receives it, regardless of client listener registration. The payload does not carry session contents or credentials.

Trust Boundaries and Controls

• observed — The existing host credential check protects /events. Relay access additionally checks JWT validity, organization membership, and host access before forwarding. These controls are unchanged by the PR. Client workspace filtering is not a server-side authorization boundary.
• inferred — No new cross-workspace privilege gain was demonstrated: authenticated host callers could already list sessions without a workspace filter, and existing events use host-wide delivery. The PR adds activity timing within that authority rather than establishing workspace-level isolation.

Resilience and Maintainability Implications

• observed — Startup failure discards the newly created session and sends another invalidation. Repeated discard is gated by row existence, and close announces only when the session was live. Notifications do not become the authority for stored status or ownership.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 13.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 15 functions across 29 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title uses conventional commit format and clearly identifies the host-service event notification as the main change.
Description check	✅ Passed	The description explains what changed, why it changed, how the event works, and how the author tested it. It does not include the template’s Checklist section, but the description is otherwise detaile…

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[greptile-apps]

Confidence Score: 4/5

[Medium risk] Adds chat session status change events to the event bus.

The PR appears safe to merge, though notification callbacks should be isolated from journal writes.

Findings

1.  Observer errors escape journal writes ▶

Fix with agent prompt

### Issue 1
packages/chat-runtime/src/journal/journal/journal.ts:150
If an `onSessionChanged` callback throws, the error escapes after the session row has been written. During `createSession`, `journal.open()` runs before the startup cleanup block, so the request fails and leaves a stored session with no live harness. Isolate notification errors from journal operations.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

The PR adds chat-session status notifications from the durable journal through the host-service /events bus and routes them to workspace-client listeners.

• Emits on creation, status transitions, epoch-reset reopen, and discard.
• Adds a typed bus message and workspace-scoped client listener payload.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  J[ChatJournal status write] --> N[onSessionChanged]
  N --> H[Host EventBus broadcast]
  H --> C[workspace-client listener]

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_{Reviews (1) · Last reviewed commit: "feat(host-service): emit chat:session-ch..."}

[coderabbitai]

Actionable comments posted: 1

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Inline comments:
Review comments at @packages/chat-runtime/src/journal/journal/journal.ts:
- Around line 63-70: Update notify to catch exceptions from the onSessionChanged
callback so listener failures do not propagate from open, appendEnvelope, or
discard after their state changes are committed.

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• packages/chat-runtime/src/index.ts
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• packages/chat-runtime/src/journal/journal/index.ts
• packages/chat-runtime/src/journal/journal/journal.test.ts
• packages/chat-runtime/src/journal/journal/journal.ts
• packages/host-service/src/app.ts
• packages/host-service/src/chat-v3/mount.ts
• packages/host-service/src/events/event-bus.ts
• packages/host-service/src/events/index.ts
• packages/host-service/src/events/types.ts
• packages/workspace-client/src/index.ts
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Inline comments:
Review comments at @packages/chat-runtime/src/journal/journal/journal.ts:
- Line 166: Update ChatJournal.notify to handle rejected Promises returned by
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• packages/chat-runtime/src/db/schema/schema.ts
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• packages/chat-runtime/src/journal/journal/journal.test.ts
• packages/chat-runtime/src/journal/journal/journal.ts
• packages/chat-runtime/src/projection/projection.ts
• packages/host-service/src/app.ts
• packages/host-service/src/events/event-bus.test.ts
• packages/host-service/src/events/types.ts
• packages/workspace-client/src/lib/eventBus.test.ts
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[saddlepaddle]

The event on /events is the right place, and I'm fine with that part. Two things to unblock it:

1. Make the payload agree with listSessions. #8157 adds live to listSessions, but this event is silent on closeSession and on a host restart, so a client that follows only the event shows running for a session with no process. Either cut the message to a nudge ({ workspaceId, occurredAt }, like agent:bindings-changed and page-watch:changed) and let the client refetch listSessions, or keep the payload and also fire on close/restart. The nudge also removes removed and the title gap (the event does not fire when the title changes).
2. Run it once against a real host with a live agent. The test plan leaves that box open, and the wiring in mount.ts and app.ts is covered by typecheck only.

SDK: please don't add this to the SDK for now, unless Roster needs it. The SDK is probably not in its final shape, and this publishes the event payload and the host routing (removed in #7564) as public API in alpha.13. If Roster does need it, tell me which calls, and put only those in a separate PR.

Smaller, fine as follow-ups: ChatJournal.open() reads the session row three times for a re-open case that cannot occur (openEpoch already returns minted), and occurredAt in app.ts is a second Date.now() where the journal's ts would match the row's updatedAt.

[saddlepaddle]

Approving so you can keep going. The comments in my review above still stand: sort out the payload vs listSessions, run it once against a real host, and leave the SDK part out unless Roster needs it.

[harshithmullapudi]

@saddlepaddle thanks. Addressed in 3d9c652:

1. Payload vs listSessions. It is now a nudge, chat:sessions-changed with { workspaceId, occurredAt }, and the client refetches listSessions. It fires when the journal writes a listing change: create or re-epoch, status, title or queued count, and discard. It also fires when closeSession stops a live agent, because that changes liveness without a journal write. A host restart sends nothing, since no client is connected then; clients refetch when they reconnect.
2. Real host. I ran the chat-v3 routes and EventBus together, wired as in app.ts, with a real claude-acp agent over HTTP. Each step of create → idle → prompt → running → idle sent a nudge, and the agent replied OK. closeSession sent one nudge and live became false. A harness start failure went to dead and also sent a nudge. This was not the full desktop app.
3. SDK. Removed from this PR. Roster will call the HTTP endpoints directly.
4. Follow-ups. open() now uses openEpoch's minted, and occurredAt uses the journal's ts.

superset-home review: both findings were in the SDK. The relay /chat-v3/trpc HTTP forwarding is fixed on main by #8159, and the token-forgetting issue no longer applies.