Codewalkers/docs/dispatch-events.md

# Dispatch & Events

`apps/server/dispatch/` — Task and phase dispatch queues. `apps/server/events/` — Typed event bus.

## Event Bus

`apps/server/events/` — Typed pub/sub system for inter-module communication.

### Architecture
- **Port**: `EventBus` interface with `emit(event)` and `on(type, handler)`
- **Adapter**: `TypedEventBus` using Node.js `EventEmitter`
- All events implement `BaseEvent { type, timestamp, payload }`

### Event Types (58)

| Category | Events | Count |
|----------|--------|-------|
| **Agent** | `agent:spawned`, `agent:stopped`, `agent:crashed`, `agent:resumed`, `agent:account_switched`, `agent:deleted`, `agent:waiting`, `agent:output` | 8 |
| **Task** | `task:queued`, `task:dispatched`, `task:completed`, `task:blocked` | 4 |
| **Phase** | `phase:queued`, `phase:started`, `phase:completed`, `phase:blocked`, `phase:changes_requested` | 5 |
| **Merge** | `merge:queued`, `merge:started`, `merge:completed`, `merge:conflicted` | 4 |
| **Page** | `page:created`, `page:updated`, `page:deleted` | 3 |
| **Process** | `process:spawned`, `process:stopped`, `process:crashed` | 3 |
| **Server** | `server:started`, `server:stopped` | 2 |
| **Worktree** | `worktree:created`, `worktree:removed`, `worktree:merged`, `worktree:conflict` | 4 |
| **Account** | `account:credentials_refreshed`, `account:credentials_expired`, `account:credentials_validated` | 3 |
| **Preview** | `preview:building`, `preview:ready`, `preview:stopped`, `preview:failed` | 4 |
| **Conversation** | `conversation:created`, `conversation:answered` | 2 | `conversation:created` triggers auto-resume of idle target agents via `resumeForConversation()` |
| **Chat** | `chat:message_created`, `chat:session_closed` | 2 | Chat session lifecycle events |
| **Initiative** | `initiative:pending_review`, `initiative:review_approved`, `initiative:changes_requested` | 3 | Initiative-level review gate events |
| **Project** | `project:synced`, `project:sync_failed` | 2 | Remote sync results from `ProjectSyncManager` |
| **Log** | `log:entry` | 1 |

### Key Event Payloads

```typescript
AgentSpawnedEvent    { agentId, name, taskId, worktreeId, provider }
AgentStoppedEvent    { agentId, name, taskId, reason }
  // reason: 'user_requested'|'task_complete'|'error'|'waiting_for_input'|
  //         'context_complete'|'plan_complete'|'detail_complete'|'refine_complete'|'chat_complete'
AgentWaitingEvent    { agentId, name, taskId, sessionId, questions[] }
AgentOutputEvent     { agentId, stream, data }
TaskCompletedEvent   { taskId, agentId, success, message }
TaskQueuedEvent      { taskId, priority, dependsOn[] }
PhaseStartedEvent    { phaseId, initiativeId }
MergeConflictedEvent { taskId, agentId, worktreeId, targetBranch, conflictingFiles[] }
PhaseChangesRequestedEvent { phaseId, initiativeId, taskId, commentCount }
AccountCredentialsRefreshedEvent { accountId, expiresAt, previousExpiresAt? }
InitiativePendingReviewEvent   { initiativeId, branch }
InitiativeReviewApprovedEvent  { initiativeId, branch, strategy: 'push_branch' | 'merge_and_push' }
InitiativeChangesRequestedEvent { initiativeId, phaseId, taskId }
```

## Task Dispatch

`apps/server/dispatch/` — In-memory queue with dependency-ordered dispatch.

### Architecture
- **Port**: `DispatchManager` interface
- **Adapter**: `DefaultDispatchManager`

### How Task Dispatch Works

1. **Queue** — `queue(taskId)` fetches task dependencies, adds to internal Map
2. **Dispatch** — `dispatchNext()` finds highest-priority task with all deps complete
3. **Context gathering** — Before spawn, `dispatchNext()` gathers initiative context (initiative, phase, tasks, pages) and passes as `inputContext` to the agent. Agents receive `.cw/input/task.md`, `initiative.md`, `phase.md`, `context/tasks/`, `context/phases/`, and `pages/`.
4. **Priority order**: high > medium > low, then oldest first (FIFO within priority)
5. **Planning skip** — Planning-category tasks (research, discuss, plan, detail, refine) skip auto-dispatch — they use the architect flow
7. **Summary propagation** — `completeTask()` reads the completing agent's `result.message` and stores it on the task's `summary` column. Dependent tasks see this summary in `context/tasks/<id>.md` frontmatter.
8. **Spawn failure** — If `agentManager.spawn()` throws, the task is blocked via `blockTask()` with the error message. The dispatch cycle continues instead of crashing.
9. **Retry blocked** — `retryBlockedTask(taskId)` resets a blocked task to pending and re-queues it. Exposed via tRPC `retryBlockedTask` mutation. The UI shows a Retry button in the task slide-over when status is `blocked`.
10. **Branch validation** — Branch computation and `ensureBranch` errors are fatal for execution tasks (execute, verify, merge, review) but non-fatal for planning tasks. This prevents agents from spawning without proper branch isolation.

### DispatchManager Methods

| Method | Purpose |
|--------|---------|
| `queue(taskId)` | Add task to dispatch queue |
| `dispatchNext()` | Find and dispatch next ready task |
| `getNextDispatchable()` | Get next task without dispatching |
| `completeTask(taskId, agentId?)` | Complete task |
| `blockTask(taskId, reason)` | Block task with reason |
| `retryBlockedTask(taskId)` | Reset blocked task to pending and re-queue |
| `getQueueState()` | Return queued, ready, blocked tasks |

## Phase Dispatch

`DefaultPhaseDispatchManager` — Same pattern for phases:

1. **Queue** — `queuePhase(phaseId)` validates phase is approved, gets dependencies
2. **Dispatch** — `dispatchNextPhase()` finds phase with all deps complete
3. **Branch creation** — Initiative and phase branches are created in all linked project clones. On failure, the phase is blocked via `blockPhase()` and tasks are NOT queued.
4. **Auto-queue tasks** — When phase starts (branches confirmed), pending execution tasks are queued (planning-category tasks excluded)
5. **Events** — `phase:queued`, `phase:started`, `phase:completed`, `phase:blocked`

### PhaseDispatchManager Methods

| Method | Purpose |
|--------|---------|
| `queuePhase(phaseId)` | Queue approved phase |
| `dispatchNextPhase()` | Start next ready phase, auto-queue its tasks |
| `getNextDispatchablePhase()` | Get next phase without dispatching |
| `completePhase(phaseId)` | Mark phase complete |
| `blockPhase(phaseId, reason)` | Block phase |
| `getPhaseQueueState()` | Return queued, ready, blocked phases |

## Auto-Dispatch (ExecutionOrchestrator)

`apps/server/execution/orchestrator.ts` — Connects the queue to agent spawning via event-driven auto-dispatch.

### Trigger Events

| Event | Action |
|-------|--------|
| `phase:queued` | Dispatch ready phases → dispatch their tasks to idle agents |
| `agent:stopped` | Auto-complete task (unless user_requested), re-dispatch queued tasks (freed agent slot) |
| `agent:crashed` | Auto-retry crashed task up to `MAX_TASK_RETRIES` (3). Increments `retryCount`, resets status to `pending`, re-queues. Exceeding retries leaves task `in_progress` for manual intervention. |
| `task:completed` | Merge task branch (if branch exists), check phase completion, dispatch next queued task |

### Crash Recovery

When an agent crashes (`agent:crashed` event), the orchestrator automatically retries the task:
1. Finds the task associated with the crashed agent
2. Checks `task.retryCount` against `MAX_TASK_RETRIES` (3)
3. If under limit: increments `retryCount`, resets task to `pending`, re-queues for dispatch
4. If over limit: logs warning, task stays `in_progress` for manual intervention

On server restart, `recoverDispatchQueues()` also recovers stuck `in_progress` tasks whose agents are dead (status is not `running` or `waiting_for_input`). These are reset to `pending` and re-queued.

Manual retry via `retryBlockedTask()` resets `retryCount` to 0, giving the task a fresh set of automatic retries.

### Coalesced Scheduling

Multiple rapid events (e.g. several `phase:queued` from `queueAllPhases`) are coalesced into a single async dispatch cycle via `scheduleDispatch()`. The cycle loops `dispatchNextPhase()` + `dispatchNext()` until both queues are drained, then re-runs if new events arrived during execution.

### Execution Mode Behavior

- **YOLO**: phase completes → auto-merge (if branch exists, skipped otherwise) → auto-dispatch next phase → auto-dispatch tasks
- **review_per_phase**: phase completes → set `pending_review` → STOP. User approves → `approveAndMergePhase()` → merge → dispatch next phase → dispatch tasks
- **No branch**: Phase completion check runs regardless of branch existence. Merge steps are skipped; status transitions still fire. `updateTaskStatus` tRPC routes completions through `dispatchManager.completeTask()` to emit `task:completed`.
- **request-changes (phase)**: phase `pending_review` → user requests changes → creates revision task (category=`'review'`, dedup guard skips if active review exists) with threaded comments (`[comment:ID]` tags + reply threads) → phase reset to `in_progress` → agent reads comments, fixes code, writes `.cw/output/comment-responses.json` → OutputHandler creates reply comments and optionally resolves threads → phase returns to `pending_review`
- **request-changes (initiative)**: initiative `pending_review` → user requests changes → creates/reuses "Finalization" phase → creates review task → initiative reset to `active` → agent fixes → initiative returns to `pending_review`