fix(pi-claude-cli): defer to engine StuckTaskDetector instead of 300s subprocess kill

The engine already runs a StuckTaskDetector with a configurable per-task
heartbeat (default 1 hour) and aborts triage/executor sessions through
AbortSignal when it judges them quiet. pi-claude-cli forwards that signal to
the subprocess. The 300s subprocess-level inactivity timeout was a redundant,
much-tighter shadow that kept killing Sonnet 4.6 mid-thinking on the 40k-char
triage prompt — exactly what the engine-level detector is designed not to do.

Move the local timeout to 30 minutes purely as a last-resort guard for embeds
that don't pass an abort signal. Stuck-detection responsibility now lives in
the caller, where it can be configured per task.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/pi-claude-cli/src/__tests__/provider.test.ts

@@ -1292,7 +1292,7 @@ describe("streamViaCli", () => {
   });
 
   describe("inactivity timeout", () => {
-    it("kills subprocess and pushes error after 300s of no output", async () => {
+    it("kills subprocess and pushes error after 1800s of no output", async () => {
       const model = mockModels[0] as any;
       const context = {
         messages: [{ role: "user", content: "Hello" }],
@@ -1303,8 +1303,8 @@ describe("streamViaCli", () => {
 
       const proc = (spawn as any).mock.results[0].value;
 
-      // Advance timers by 300 seconds without writing to stdout
+      // Advance timers by 1800 seconds without writing to stdout
-      await vi.advanceTimersByTimeAsync(300_000);
+      await vi.advanceTimersByTimeAsync(1_800_000);
 
       const mockStream = MockAssistantMessageEventStream.mock.instances[0];
       const doneEvent = mockStream._events.find(
@@ -1331,7 +1331,7 @@ describe("streamViaCli", () => {
       const proc = (spawn as any).mock.results[0].value;
 
       // Advance to 290s then write a line (just under the 300s cap)
-      await vi.advanceTimersByTimeAsync(290_000);
+      await vi.advanceTimersByTimeAsync(1_790_000);
 
       // Write a stream event line
       proc.stdout.write(
@@ -1346,7 +1346,7 @@ describe("streamViaCli", () => {
       await vi.advanceTimersByTimeAsync(0);
 
       // Advance another 290s (580s total, 290s since last line) -- should NOT timeout
-      await vi.advanceTimersByTimeAsync(290_000);
+      await vi.advanceTimersByTimeAsync(1_790_000);
 
       const mockStream = MockAssistantMessageEventStream.mock.instances[0];
       const doneEvent = mockStream._events.find(
@@ -1354,7 +1354,7 @@ describe("streamViaCli", () => {
       );
       expect(doneEvent).toBeUndefined();
 
-      // Advance 10 more seconds (300s since last line) -- NOW should timeout
+      // Advance 10 more seconds (1800s since last line) -- NOW should timeout
       await vi.advanceTimersByTimeAsync(10_000);
 
       const doneEvent2 = mockStream._events.find(
@@ -1401,7 +1401,7 @@ describe("streamViaCli", () => {
       await vi.advanceTimersByTimeAsync(100);
 
       // Advance past 180s -- should NOT timeout since result was received
-      await vi.advanceTimersByTimeAsync(300_000);
+      await vi.advanceTimersByTimeAsync(1_800_000);
 
       const mockStream = MockAssistantMessageEventStream.mock.instances[0];
       const errorEvents = mockStream._events.filter(

packages/pi-claude-cli/src/provider.ts

@@ -45,13 +45,22 @@ import { handleControlRequest } from "./control-handler.js";
 import { mapThinkingEffort } from "./thinking-config.js";
 import { isPiKnownClaudeTool } from "./tool-mapping.js";
 /**
- * Inactivity timeout: kill the Claude CLI subprocess if no stdout arrives
+ * Inactivity safety net for the Claude CLI subprocess.
- * for this long. Sonnet 4.6 with extended thinking on large system prompts
+ *
- * (e.g. the triage prompt + AGENTS.md + skill blocks ~ 40k chars) can take
+ * Set very high (30 minutes) because the caller is the authoritative source of
- * minutes between thinking deltas; a 3-minute timeout was killing those
+ * truth for "this session is stuck": Fusion's engine runs a `StuckTaskDetector`
- * sessions before they could call fn_review_spec. Bump to 5 minutes.
+ * with a configurable heartbeat (default 1 hour) and aborts the session via
+ * `AbortSignal` when it decides the agent has gone quiet. pi-claude-cli already
+ * forwards that signal to the subprocess (`forceKillProcess` on `signal.abort`).
+ *
+ * A short timeout here was racing the engine: Sonnet 4.6 with extended thinking
+ * on the triage prompt (~40k chars) routinely goes >3 minutes between thinking
+ * deltas, and we were killing those subprocesses before they could write
+ * PROMPT.md and call `fn_review_spec`. The half-hour ceiling is just a
+ * last-resort guard for catastrophically hung processes when no abort signal
+ * arrives (e.g. someone embeds pi-claude-cli without a stuck detector).
  */
-const INACTIVITY_TIMEOUT_MS = 300_000;
+const INACTIVITY_TIMEOUT_MS = 30 * 60_000;
 
 /** Extended stream options: pi's SimpleStreamOptions plus optional cwd and mcpConfigPath */
 type StreamViaCLiOptions = SimpleStreamOptions & {