feat(daemon): non-blocking POST /prompt — return 202 with promptId

packages/acp-bridge/src/bridge.ts

@@ -481,6 +481,50 @@ function broadcastPromptCancelledOnce(
   broadcastPromptCancelled(entry, sessionId, originatorClientId, reason);
 }
 
+function broadcastTurnComplete(
+  entry: SessionEntry,
+  sessionId: string,
+  promptResult: { stopReason?: string; [k: string]: unknown },
+  promptId: string | undefined,
+  originatorClientId: string | undefined,
+): void {
+  entry.events.publish({
+    type: 'turn_complete',
+    data: {
+      sessionId,
+      stopReason: promptResult.stopReason ?? 'end_turn',
+      ...(promptId ? { promptId } : {}),
+    },
+    ...(originatorClientId ? { originatorClientId } : {}),
+  });
+}
+
+function broadcastTurnError(
+  entry: SessionEntry,
+  sessionId: string,
+  err: unknown,
+  promptId: string | undefined,
+  originatorClientId: string | undefined,
+): void {
+  const message = err instanceof Error ? err.message : String(err);
+  const code =
+    err instanceof Error &&
+    'code' in err &&
+    typeof (err as Error & { code?: unknown }).code === 'string'
+      ? (err as Error & { code: string }).code
+      : undefined;
+  entry.events.publish({
+    type: 'turn_error',
+    data: {
+      sessionId,
+      message,
+      ...(code ? { code } : {}),
+      ...(promptId ? { promptId } : {}),
+    },
+    ...(originatorClientId ? { originatorClientId } : {}),
+  });
+}
+
 function hasControlCharacter(value: string): boolean {
   for (let i = 0; i < value.length; i += 1) {
     const code = value.charCodeAt(i);
@@ -2263,6 +2307,28 @@ export function createHttpAcpBridge(opts: BridgeOptions): HttpAcpBridge {
         }
         return racedPromise;
       });
+      const promptId = context?.promptId;
+      result.then(
+        (promptResult) => {
+          broadcastTurnComplete(
+            entry,
+            sessionId,
+            promptResult,
+            promptId,
+            originatorClientId,
+          );
+        },
+        (err) => {
+          if (err instanceof DOMException && err.name === 'AbortError') return;
+          broadcastTurnError(
+            entry,
+            sessionId,
+            err,
+            promptId,
+            originatorClientId,
+          );
+        },
+      );
       // Tail swallows failures so subsequent prompts still run. The caller
       // still sees rejections on its own `result` reference.
       entry.promptQueue = result.then(
@@ -2339,6 +2405,12 @@ export function createHttpAcpBridge(opts: BridgeOptions): HttpAcpBridge {
       return entry.events.subscribe(subOpts);
     },
 
+    getSessionLastEventId(sessionId) {
+      const entry = byId.get(sessionId);
+      if (!entry) throw new SessionNotFoundError(sessionId);
+      return entry.events.lastEventId;
+    },
+
     respondToPermission(requestId, response, context) {
       // F3 Commit 3 — legacy workspace-level vote route. Look up the
       // session via mediator's resolved+pending peek, forward to

packages/acp-bridge/src/bridgeTypes.ts

@@ -110,6 +110,13 @@ export interface BridgeClientRequestContext {
    * dedicated daemon or `designated` policy instead).
    */
   fromLoopback?: boolean;
+  /**
+   * Caller-generated correlation id for non-blocking prompt mode.
+   * When present, the bridge stamps `turn_complete` / `turn_error` events
+   * with this id so the SDK's `prompt()` can match the SSE event to the
+   * pending HTTP 202 request.
+   */
+  promptId?: string;
 }
 
 /**
@@ -191,6 +198,13 @@ export interface HttpAcpBridge {
     opts?: SubscribeOptions,
   ): AsyncIterable<BridgeEvent>;
 
+  /**
+   * Return the most recent monotonic event id for this session's bus.
+   * Used by non-blocking prompt responses to tell the client where to
+   * start SSE replay so no events are missed.
+   */
+  getSessionLastEventId(sessionId: string): number;
+
   /**
    * Explicitly close a live session. Force-closes even when other clients
    * are attached. Throws `SessionNotFoundError` for unknown ids.

packages/cli/src/serve/capabilities.ts

@@ -227,6 +227,7 @@ export const SERVE_CAPABILITY_REGISTRY = {
   },
   prompt_absolute_deadline: { since: 'v1' },
   writer_idle_timeout: { since: 'v1' },
+  non_blocking_prompt: { since: 'v1' },
 } as const satisfies Record<string, ServeCapabilityDescriptor>;
 
 export type ServeFeature = keyof typeof SERVE_CAPABILITY_REGISTRY;