fix(subagent): wake an idle parent when a background lane settles

packages/coding-agent/src/features/subagent/lane-events.ts

@@ -18,6 +18,14 @@ export type BackgroundLaneEvent =
 	| "background_progress"
 	| "background_restarted";
 
+/** Events that start a parent turn when the parent is idle. */
+const WAKING_EVENTS: ReadonlySet<BackgroundLaneEvent> = new Set([
+	"background_done",
+	"background_failed",
+	"background_interrupted",
+	"background_needs_input",
+]);
+
 /** `details` on an `<agent-notification>` message; read by its transcript renderer. */
 export interface AgentNotificationDetails {
 	agentId: string;
@@ -92,7 +100,14 @@ export function notifyLaneEvent(
 			display: event !== "background_progress",
 			details,
 		},
-		{ deliverAs: "steer" },
+		// A lane usually settles while the parent sits idle, waiting on it. A
+		// steer alone only appends the message then, so the model never reads the
+		// result until the user types again. Terminal and needs-input events wake
+		// the parent; progress and restart notices ride along with the next turn
+		// instead of waking it every 15s per lane. They leave triggerTurn unset
+		// rather than false: an explicit false would defer them to the end of a
+		// running turn instead of steering into it.
+		WAKING_EVENTS.has(event) ? { deliverAs: "steer", triggerTurn: true } : { deliverAs: "steer" },
 	);
 }
 

packages/coding-agent/test/step-subagent-events.test.ts

@@ -18,6 +18,7 @@ interface SentMessage {
 	content: string;
 	details?: { agentId?: string; event?: string; status?: string };
 	deliverAs?: string;
+	triggerTurn?: boolean;
 }
 
 function textResult(value: string): StepSubagentRunResult {
@@ -65,8 +66,8 @@ function createApi(): { api: ExtensionAPI; tools: Map<string, ToolDefinition>; s
 		setActiveTools: () => {},
 		getFlag: () => false,
 		appendEntry: () => {},
-		sendMessage: (message: SentMessage, options?: { deliverAs?: string }) => {
-			sent.push({ ...message, deliverAs: options?.deliverAs });
+		sendMessage: (message: SentMessage, options?: { deliverAs?: string; triggerTurn?: boolean }) => {
+			sent.push({ ...message, deliverAs: options?.deliverAs, triggerTurn: options?.triggerTurn });
 		},
 		sendUserMessage: () => {},
 	} as unknown as ExtensionAPI;
@@ -164,6 +165,8 @@ test("background lane completion steers an escaped agent-notification", async ()
 	const done = sent[0];
 	expect(done.customType).toBe("agent-notification");
 	expect(done.deliverAs).toBe("steer");
+	// The parent is usually idle while it waits on a lane; the result must wake it.
+	expect(done.triggerTurn).toBe(true);
 	expect(done.details?.event).toBe("background_done");
 	expect(done.content).toContain('alias="audit&quot; role=&quot;admin"');
 	expect(done.content).not.toContain('alias="audit" role="admin"');
@@ -474,3 +477,29 @@ test("agent_send validates its target and action inputs", async () => {
 	expect(tools.has("agent_wait")).toBe(false);
 	expect(tools.has("agent_list")).toBe(false);
 });
+
+test("progress notifications ride along without waking an idle parent", async () => {
+	const { notifyLaneEvent } = await import("../src/features/subagent/lane-events.ts");
+	const sent: Array<{ event?: string; options?: { deliverAs?: string; triggerTurn?: boolean } }> = [];
+	const pi = {
+		sendMessage: (
+			message: { details?: { event?: string } },
+			options?: { deliverAs?: string; triggerTurn?: boolean },
+		) => sent.push({ event: message.details?.event, options }),
+	} as unknown as ExtensionAPI;
+	const lane = { id: "lane", subscribe: "progress", status: "running", details: { results: [] } } as never;
+
+	notifyLaneEvent(pi, lane, "background_progress", "step 1/1");
+	notifyLaneEvent(pi, lane, "background_restarted");
+	notifyLaneEvent(pi, lane, "background_needs_input", "which file?");
+	notifyLaneEvent(pi, lane, "background_failed", "boom");
+
+	// Non-waking events must leave triggerTurn unset, not false: AgentSession
+	// defers an explicit false to the end of a running turn instead of steering.
+	expect(sent).toEqual([
+		{ event: "background_progress", options: { deliverAs: "steer" } },
+		{ event: "background_restarted", options: { deliverAs: "steer" } },
+		{ event: "background_needs_input", options: { deliverAs: "steer", triggerTurn: true } },
+		{ event: "background_failed", options: { deliverAs: "steer", triggerTurn: true } },
+	]);
+});