From 9a3510f23683a884907b5f9b1b20cd161483f059 Mon Sep 17 00:00:00 2001
From: Cristian <seeve.c@gmail.com>
Date: Wed, 2 Sep 2026 10:47:08 +0000
Subject: [PATCH] fix(actor-system): release spawn gate before start

---
 .changeset/release-nested-spawn-gate.md |  5 +++++
 src/actor.ts                            | 17 ++++++++---------
 test/actor.test.ts                      | 24 ++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 9 deletions(-)
 create mode 100644 .changeset/release-nested-spawn-gate.md

diff --git a/.changeset/release-nested-spawn-gate.md b/.changeset/release-nested-spawn-gate.md
new file mode 100644
index 0000000..a7d7543
--- /dev/null
+++ b/.changeset/release-nested-spawn-gate.md
@@ -0,0 +1,5 @@
+---
+"effect-machine": patch
+---
+
+Allow nested actors to start before their parent spawn returns.
diff --git a/src/actor.ts b/src/actor.ts
index 2d03a53..c64b246 100644
--- a/src/actor.ts
+++ b/src/actor.ts
@@ -1262,10 +1262,6 @@ const make = Effect.fn("effect-machine.actorSystem.make")(function* () {
     actorRef = actor as unknown as ActorRef<AnyState, unknown>;
     // Register before start — actor is in the map before lifecycle hooks fire
     yield* registerActor(id, actor);
-    // Auto-start: system.spawn returns a running actor
-    yield* actor.start.pipe(
-      Effect.catchCause((cause) => actor.stop.pipe(Effect.andThen(Effect.failCause(cause)))),
-    );
     return actor;
   });
 
@@ -1282,11 +1278,14 @@ const make = Effect.fn("effect-machine.actorSystem.make")(function* () {
     options?: SystemSpawnOptions<S, E, Input>,
   ): Effect.Effect<ActorRef<S, E, Output>, DuplicateActorError, R> => {
     const id = actorSystemId(idOrKey);
-    return withSpawnGate(spawnRegular(id, machine, options)) as Effect.Effect<
-      ActorRef<S, E, Output>,
-      DuplicateActorError,
-      R
-    >;
+    return withSpawnGate(spawnRegular(id, machine, options)).pipe(
+      Effect.flatMap((actor) =>
+        actor.start.pipe(
+          Effect.catchCause((cause) => actor.stop.pipe(Effect.andThen(Effect.failCause(cause)))),
+          Effect.as(actor),
+        ),
+      ),
+    ) as Effect.Effect<ActorRef<S, E, Output>, DuplicateActorError, R>;
   };
 
   function get<S extends AnyState, E, Output>(
diff --git a/test/actor.test.ts b/test/actor.test.ts
index e1ace1e..03118b8 100644
--- a/test/actor.test.ts
+++ b/test/actor.test.ts
@@ -97,6 +97,30 @@ describe("ActorSystem", () => {
     }).pipe(Effect.provide(ActorSystemDefault)),
   );
 
+  it.scopedLive("registers a nested child before parent spawn returns", () =>
+    Effect.gen(function* () {
+      const ChildState = State({ Active: {} });
+      const ChildEvent = Event({ Stop: {} });
+      const childMachine = Machine.make({
+        state: ChildState,
+        event: ChildEvent,
+        initial: ChildState.Active,
+      });
+      const parentMachine = Machine.make({
+        state: TestState,
+        event: TestEvent,
+        initial: TestState.Idle,
+      }).spawn(TestState.Idle, ({ self }) =>
+        self.spawn("nested-child", childMachine).pipe(Effect.asVoid, Effect.orDie),
+      );
+      const system = yield* ActorSystemService;
+
+      yield* system.spawn("nested-parent", parentMachine);
+
+      expect((yield* system.get("nested-child"))._tag).toBe("Some");
+    }).pipe(Effect.provide(ActorSystemDefault)),
+  );
+
   it.scopedLive("stops actors properly", () =>
     Effect.gen(function* () {
       const machine = Machine.make({