Goal

When the app reconnects or misses a short burst of session events, it can recover missed question, permission, and status updates without relying only on frontend fallback polling.

Scope

In scope:

• Design a server-side event id / cursor model for session-related SSE events.
• Let the client reconnect with its last seen event id.
• Replay recent missed events for question, permission, and session/status updates.
• Keep replay bounded so it does not grow memory unbounded.
• Preserve the frontend fallback added in refactor(app): modularize session todo and blocker state #394 as a safety net.
• Fix or unblock the question fallback UI e2e seeding path.
• Add UI e2e coverage for lost question.asked / delayed question.list recovery.

Out of scope:

• Rewriting all sync/bootstrap logic.
• Changing todo identity/revision.
• Redesigning the composer dock UI.

Relevant files or context

Related PR:

• refactor(app): modularize session todo and blocker state #394

Likely areas:

• packages/opencode/ event/SSE/session sync code
• packages/app/src/context/sync.tsx
• packages/app/src/context/global-sync.tsx
• packages/app/src/context/global-sync/event-reducer.ts
• packages/app/src/pages/session/blockers/question-reconcile.ts
• packages/app/src/pages/session/blockers/use-session-blockers.ts
• packages/app/e2e/session/session-composer-dock.spec.ts

Context:

• refactor(app): modularize session todo and blocker state #394 added bounded frontend recovery for missing/delayed question requests.
• That fallback is useful, but backend replay is the more durable fix for missed SSE events.
• The current question UI e2e for the fallback path was blocked by test seeding before UI assertions.

Verification

• Add unit/integration coverage for reconnecting with a last seen event id.
• Verify duplicate replayed events do not create duplicate questions/permissions.
• Verify out-of-order or already-resolved question events do not reopen stale UI.
• Add or unblock UI e2e coverage for delayed/lost question.asked recovery.
• Existing refactor(app): modularize session todo and blocker state #394 blocker/todo focused tests continue to pass.

Execution mode

Agent should investigate and propose a plan first.