fix(desktop): bound backend shutdown wait during quit

apps/desktop/src/app/DesktopApp.ts

@@ -1,4 +1,5 @@
 import * as Cause from "effect/Cause";
+import * as Duration from "effect/Duration";
 import * as Effect from "effect/Effect";
 import * as Option from "effect/Option";
 import * as Ref from "effect/Ref";
@@ -142,6 +143,20 @@ const handleFatalStartupError = Effect.fn("desktop.startup.handleFatalStartupErr
 const fatalStartupCause = <E>(stage: string, cause: Cause.Cause<E>) =>
   handleFatalStartupError(stage, Cause.pretty(cause)).pipe(Effect.andThen(Effect.failCause(cause)));
 
+export const stopAllPoolInstances = Effect.fn("desktop.app.stopAllPoolInstances")(
+  function* (): Effect.fn.Return<void, never, DesktopBackendPool.DesktopBackendPool> {
+    // Stop every backend in the pool with a timeout to guarantee the quit
+    // path makes progress even if a backend hangs during teardown.
+    const pool = yield* DesktopBackendPool.DesktopBackendPool;
+    const instances = yield* pool.list;
+    yield* Effect.forEach(
+      instances,
+      (instance) => instance.stop({ timeout: Duration.seconds(5) }),
+      { concurrency: "unbounded" },
+    );
+  },
+);
+
 const bootstrap = Effect.gen(function* () {
   const pool = yield* DesktopBackendPool.DesktopBackendPool;
   const primaryBackend = yield* pool.primary;
@@ -313,18 +328,12 @@ const scopedProgram = Effect.scoped(
     const shutdown = yield* DesktopShutdown.DesktopShutdown;
 
     yield* Effect.addFinalizer(() =>
-      Effect.gen(function* () {
-        const pool = yield* DesktopBackendPool.DesktopBackendPool;
-        // Stop every backend in the pool, not just the primary. The
-        // electronApp.quit() path can race ahead of the layer-scope
-        // cascade, so leaving the WSL instance for its parent scope
-        // finalizer means it gets hard-killed by the OS instead of
-        // receiving SIGTERM + grace. Stops run concurrently.
-        const instances = yield* pool.list;
-        yield* Effect.forEach(instances, (instance) => instance.stop(), {
-          concurrency: "unbounded",
-        });
-      }).pipe(Effect.ensuring(shutdown.markComplete)),
+      // Stop every backend in the pool, not just the primary. The
+      // electronApp.quit() path can race ahead of the layer-scope
+      // cascade, so leaving the WSL instance for its parent scope
+      // finalizer means it gets hard-killed by the OS instead of
+      // receiving SIGTERM + grace.
+      stopAllPoolInstances().pipe(Effect.ensuring(shutdown.markComplete)),
     );
 
     yield* startup;

apps/desktop/src/backend/DesktopBackendManager.test.ts

@@ -23,6 +23,8 @@ import { HttpClient, HttpClientRequest, HttpClientResponse } from "effect/unstab
 import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process";
 
 import * as DesktopBackendManager from "./DesktopBackendManager.ts";
+import * as DesktopApp from "../app/DesktopApp.ts";
+import * as DesktopBackendPool from "./DesktopBackendPool.ts";
 import * as DesktopObservability from "../app/DesktopObservability.ts";
 import * as DesktopTelemetryPublisher from "../telemetry/DesktopTelemetryPublisher.ts";
 import * as DesktopWslEnvironment from "../wsl/DesktopWslEnvironment.ts";
@@ -1503,4 +1505,76 @@ describe("DesktopBackendManager", () => {
       }).pipe(Effect.provide(TestClock.layer())),
     ),
   );
+
+  it.effect("stopAllPoolInstances bounds the quit finalizer when backends hang", () =>
+    Effect.scoped(
+      Effect.gen(function* () {
+        // Each backend's process-scope finalizer reports when it starts and
+        // when it finishes, keyed by instance name, so the test can prove
+        // both backends reached each milestone instead of inferring it from
+        // a shared flag or a clock advance.
+        const teardownStarted = yield* Queue.unbounded<string>();
+        const teardownFinished = yield* Queue.unbounded<string>();
+        const allowTeardown = yield* Deferred.make<void>();
+
+        const makeInstance = (name: string) =>
+          makeTestInstance({
+            spawnerLayer: Layer.succeed(
+              ChildProcessSpawner.ChildProcessSpawner,
+              ChildProcessSpawner.make(() =>
+                Effect.gen(function* () {
+                  const scope = yield* Scope.Scope;
+                  yield* Scope.addFinalizer(
+                    scope,
+                    Queue.offer(teardownStarted, name).pipe(
+                      Effect.andThen(Deferred.await(allowTeardown)),
+                      Effect.andThen(Queue.offer(teardownFinished, name)),
+                      Effect.asVoid,
+                    ),
+                  );
+                  return makeProcess({ exitCode: Effect.never });
+                }),
+              ),
+            ),
+            httpClientLayer: httpClientLayer(() => Effect.never),
+          });
+
+        const instance1 = yield* makeInstance("instance1");
+        const instance2 = yield* makeInstance("instance2");
+
+        yield* instance1.start;
+        yield* instance2.start;
+
+        const mockPool = Layer.succeed(DesktopBackendPool.DesktopBackendPool, {
+          list: Effect.succeed([instance1, instance2]),
+          get: () => Effect.succeed(Option.none()),
+          primary: Effect.die(new Error("primary not implemented")),
+          register: () => Effect.die(new Error("register not implemented")),
+          unregister: () => Effect.die(new Error("unregister not implemented")),
+        });
+
+        // Mirror the quit path: register stopAllPoolInstances as a scope
+        // finalizer and let the scope close run it, rather than calling it
+        // as an ordinary interruptible effect.
+        const quitFiber = yield* Effect.scoped(
+          Effect.addFinalizer(() => DesktopApp.stopAllPoolInstances()),
+        ).pipe(Effect.provide(mockPool), Effect.forkChild);
+
+        const started = yield* Queue.takeN(teardownStarted, 2);
+        assert.deepEqual(started.toSorted(), ["instance1", "instance2"]);
+
+        // Both backends are now hung in teardown. Advancing past the 5s
+        // budget must let the quit finalizer return without them.
+        yield* TestClock.adjust(Duration.seconds(5));
+        yield* Fiber.join(quitFiber);
+        assert.equal(yield* Queue.size(teardownFinished), 0);
+
+        // The timed-out closes keep running in the background and finish
+        // once the backends unblock.
+        yield* Deferred.succeed(allowTeardown, undefined);
+        const finished = yield* Queue.takeN(teardownFinished, 2);
+        assert.deepEqual(finished.toSorted(), ["instance1", "instance2"]);
+      }).pipe(Effect.provide(TestClock.layer())),
+    ),
+  );
 });