chore: remove stale agent-event-stream-redesign doc

This commit is contained in:
Mohamed Boudra
2026-03-26 20:56:03 +07:00
parent 7892b3cbe1
commit c667aca3e0

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# Agent Event Stream Redesign
Status: **Implemented** (2026-03-24)
## Problem
The Claude provider had three event paths delivering the same events to the agent-manager:
1. **Foreground stream** (`stream()``activeForegroundTurn.queue`)
2. **Live event pump** (`streamLiveEvents()``liveEventQueue`) fed by the query pump
3. **JSONL history poller** (`startLiveHistoryPolling()``routeSdkMessageFromPump()`)
Routing between paths was timing-based (`Boolean(activeForegroundTurn)`, `pendingRun`). This caused:
- **Duplicate user messages**: trailing SDK events routed to the live queue after `activeForegroundTurn` cleared
- **Stuck running state**: stale `turn_started` from the live path flipped lifecycle back to `running` after finalize set it to terminal
- **Fragile dedup**: `shouldSuppressLiveUserMessageEcho` checked `pendingRun` (already null) and `messageId` (Claude assigns its own UUID)
Codex and OpenCode were stable because they had ONE event path with no routing decision.
## Design
### Core principle
One event source per provider session. Identity-based turn ownership, not timing-based routing.
### Provider contract (`AgentSession`)
```typescript
interface AgentSession {
readonly provider: AgentProvider;
readonly id: string | null;
readonly capabilities: AgentCapabilityFlags;
// Turn lifecycle
startTurn(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<{ turnId: string }>;
interrupt(): Promise<void>;
// Event delivery (push-based)
subscribe(callback: (event: AgentStreamEvent) => void): () => void;
// History (hydration only — never live dispatch)
streamHistory(): AsyncGenerator<AgentStreamEvent>;
// Run (uses startTurn + subscribe internally)
run(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<AgentRunResult>;
// Session metadata (unchanged)
getRuntimeInfo(): Promise<AgentRuntimeInfo>;
getAvailableModes(): Promise<AgentMode[]>;
getCurrentMode(): Promise<string | null>;
setMode(modeId: string): Promise<void>;
getPendingPermissions(): AgentPermissionRequest[];
respondToPermission(requestId: string, response: AgentPermissionResponse): Promise<void>;
describePersistence(): AgentPersistenceHandle | null;
close(): Promise<void>;
listCommands?(): Promise<AgentSlashCommand[]>;
setModel?(modelId: string | null): Promise<void>;
setThinkingOption?(thinkingOptionId: string | null): Promise<void>;
}
```
### Method contracts
#### `startTurn(prompt, options?): Promise<{ turnId: string }>`
Initiates a foreground turn. The provider validates readiness, generates a unique `turnId`, submits the prompt to the runtime, and resolves once accepted. Resolving means the prompt was accepted — not that the turn has started processing.
Rejects if: session not connected, foreground turn already active, runtime rejects prompt.
#### `subscribe(callback): () => void`
Registers a callback that receives ALL provider events — foreground and autonomous — in provider order. Returns an unsubscribe function. Events carry `turnId` when they belong to a turn.
#### `streamHistory(): AsyncGenerator<AgentStreamEvent>`
Yields persisted timeline items from prior sessions. Hydration only. Does NOT yield live events.
#### `interrupt(): Promise<void>`
Cancels the active foreground turn. The resulting `turn_canceled` event arrives via `subscribe()`.
### Provider-side guarantees
1. **Per-session ordering**: callbacks invoked in provider event order
2. **No concurrent callback execution**: serialized delivery per session
3. **Subscribe-before-start safety**: manager subscribes at session creation, before any `startTurn()` call — no events missed
4. **Callback error isolation**: subscriber throws → provider logs and continues
5. **Deterministic cleanup**: `close()` stops all callbacks; `unsubscribe()` stops that specific callback
### Event tagging
All turn-scoped events carry `turnId: string`. Providers stamp turnId in `notifySubscribers()` from the active turn state (`activeForegroundTurnId` or `autonomousTurn.id`). The manager derives turn kind (foreground vs autonomous) by comparing against its own `activeForegroundTurnId`.
### User message dedup
Claude SDK assigns its own UUID to user messages (does not preserve ours). The provider deduplicates user_message echoes by text content against the most recent foreground prompt.
## Manager
### Single subscription per session
When a session is loaded, the manager subscribes once via `session.subscribe()`. This is the only live input path. Events flow through a single dispatcher that handles lifecycle projection, foreground turn waiters, and UI updates.
### Lifecycle projection from turn identity
- After `startTurn()` resolves: foreground turn is active
- On `turn_started` for active foreground turnId: lifecycle = `running`
- On terminal for active foreground turnId: lifecycle = `idle` or `error`, clear foreground turn
- On autonomous `turn_started`: lifecycle = `running`
- On autonomous terminal: lifecycle = `idle` or `error`
### `streamAgent()` as filtered view
```typescript
async *streamAgent(agentId, prompt, options) {
const { turnId } = await session.startTurn(prompt, options);
agent.activeForegroundTurnId = turnId;
// Foreground turn waiter yields events matching this turnId
// Ends when terminal event for turnId arrives
}
```
### State model
| Concept | Implementation |
|---------|---------------|
| Foreground turn tracking | `activeForegroundTurnId: string \| null` |
| Lifecycle projection | From turn events via turnId matching |
| Cancellation | `session.interrupt()` + await waiter settlement |
## What was deleted
- `stream()` from `AgentSession` interface and all providers
- `Pushable<T>` async queue from all providers
- `streamLiveEvents()` capability
- `activeForegroundTurn` + foreground queue in Claude provider
- `liveEventQueue` in Claude provider
- `routeSdkMessageFromPump()` timing-based routing (simplified to direct dispatch)
- `startLiveEventPump()` in manager
- `liveEventBacklog` + `flushLiveEventBacklog()` in manager
- `shouldSuppressLiveUserMessageEcho()` in manager
- `startLiveHistoryPolling()` for live dispatch
- `snapHistoryOffsetToEnd()`
- `pendingRun` as iterator reference
## Integration tests
All tests run against real Claude sessions with credentials from `.env.test`. No mocks.
File: `packages/server/src/server/agent/providers/__tests__/claude-agent.event-stream.integration.test.ts`
| Test | What it verifies |
|------|-----------------|
| Basic foreground turn | startTurn → events via subscribe → terminal with matching turnId |
| No duplicate user_messages | Exactly ONE user_message per prompt, even after terminal |
| Lifecycle doesn't get stuck | No stale turn_started after terminal for same turnId |
| Autonomous run | sleep 5 in bg → idle → autonomous wake → idle (distinct turnIds) |
| Interruption | Start long task → interrupt → turn_canceled arrives |
| Sequential turns | Two turns produce distinct turnIds, no cross-contamination |
| Fast-fail | Quick error produces clean terminal, no stale events |
| User message dedup | Exactly one user_message with matching text in event log |
### Invariants (asserted on every test)
1. For each foreground turnId, exactly ONE `user_message` event
2. Every `turn_started` has exactly one matching terminal
3. After terminal for a foreground turnId, no later event with that turnId gets projected as autonomous
4. Autonomous turns between foreground turns are visible with distinct turnIds