feat: unify coordinator semantics (Muse role alignment phase 1)

Platform coordinator.py is the single source of truth; the skill
coordinator template (templates/roles/00-coordinator.md + SKILL.md
appendix 00 + body) now derives from it instead of describing a
second, model-played coordinator (U1-U13).

- server: _create_task accepts parent_task_id (404/400 checks,
  coordinator-under-coordinator rejected); follow-ups to a running
  coordinator return 409 at entry (_create_followup /
  _deliver_to_thread) with documented alternatives (U14/U15).
- tests: 8 new coordinator tests (depth limit, lineage, replay,
  follow-up 409); appendix sync/provenance/transplant suites green.
- check_appendix.py: 12 chapters match templates/roles/.

cloud/tests/test_coordinator.py

@@ -238,6 +238,25 @@ class WorkerCoordinatorTestCase(unittest.TestCase):
         self.assertEqual(backend["effort"], "high")
         self.assertEqual(backend["status"], "queued")
 
+    def test_sync_children_never_carry_coordinator_parts(self):
+        # 纵深防御（Muse 角色对齐 P1）：_coord_sync_children 建出
+        # 的子任务行 coordinator_parts 恒为 NULL，子任务永为普通任务。
+        _insert_task(self.db_path, "coord", coordinator_parts=self._parts())
+        worker = self._worker()
+        task = worker.get_task("coord")
+        worker._coord_sync_children(task, task["coordinator_parts"])
+        conn = sqlite3.connect(self.db_path)
+        try:
+            rows = conn.execute(
+                "SELECT id, coordinator_parts FROM tasks"
+                " WHERE parent_task_id = ?",
+                ("coord",)).fetchall()
+        finally:
+            conn.close()
+        self.assertEqual(len(rows), 2)
+        for task_id, parts in rows:
+            self.assertIsNone(parts, task_id)
+
     def test_sync_requeues_failed_keeps_completed(self):
         _insert_task(self.db_path, "coord", coordinator_parts=self._parts())
         _insert_task(self.db_path, "c-old", status="failed",
@@ -469,6 +488,103 @@ class ServerCoordinatorTestCase(unittest.TestCase):
         self.assertEqual(status, 200)
         self.assertEqual(len(data["tasks"]), 3)
 
+    def _create_task(self, extra=None):
+        body = {"project_id": self.project["id"], "prompt": "做点事"}
+        if extra:
+            body.update(extra)
+        return self._req("POST", "/tasks", body, self.owner_key)
+
+    def test_create_child_coordinator_under_plain_parent_ok(self):
+        status, parent = self._create_task()
+        self.assertEqual(status, 201)
+        status, child = self._create_coord(
+            extra={"parent_task_id": parent["id"]})
+        self.assertEqual(status, 201)
+        self.assertEqual(child["parent_task_id"], parent["id"])
+        self.assertEqual(len(child["coordinator_parts"]), 2)
+
+    def test_create_coordinator_under_coordinator_rejected(self):
+        status, coord = self._create_coord()
+        self.assertEqual(status, 201)
+        status, body = self._create_coord(
+            extra={"parent_task_id": coord["id"]})
+        self.assertEqual(status, 400)
+        self.assertIn("coordinator task cannot be created under a"
+                      " coordinator task", body["error"])
+        status, data = self._req(
+            "GET", "/tasks?project_id=" + self.project["id"],
+            key=self.owner_key)
+        self.assertEqual(status, 200)
+        self.assertEqual(len(data["tasks"]), 1)
+
+    def test_create_parent_task_checks(self):
+        status, _body = self._create_coord(
+            extra={"parent_task_id": "no-such-task"})
+        self.assertEqual(status, 404)
+        status, other = self._req(
+            "POST", "/projects", {"name": "other"}, self.owner_key)
+        self.assertEqual(status, 201)
+        status, parent = self._create_task(
+            extra={"project_id": other["id"]})
+        self.assertEqual(status, 201)
+        status, body = self._create_coord(
+            extra={"parent_task_id": parent["id"]})
+        self.assertEqual(status, 400)
+        status, body = self._create_coord(
+            extra={"parent_task_id": 123})
+        self.assertEqual(status, 400)
+
+    def test_create_lineage_without_coordinator_ok(self):
+        status, coord = self._create_coord()
+        self.assertEqual(status, 201)
+        status, child = self._create_task(
+            extra={"parent_task_id": coord["id"]})
+        self.assertEqual(status, 201)
+        self.assertEqual(child["parent_task_id"], coord["id"])
+
+    def test_create_idempotent_replay_keeps_single_task(self):
+        status, parent = self._create_task()
+        self.assertEqual(status, 201)
+        extra = {"idempotency_key": "idem-parent",
+                 "parent_task_id": parent["id"]}
+        status, first = self._create_task(extra=extra)
+        self.assertEqual(status, 201)
+        status, second = self._create_task(extra=extra)
+        self.assertEqual(status, 200)
+        self.assertEqual(second["id"], first["id"])
+        status, data = self._req(
+            "GET", "/tasks?project_id=" + self.project["id"],
+            key=self.owner_key)
+        self.assertEqual(len(data["tasks"]), 2)
+
+    def test_followup_to_coordinator_rejected(self):
+        status, coord = self._create_coord()
+        self.assertEqual(status, 201)
+        status, body = self._req(
+            "POST", "/tasks/" + coord["id"] + "/followups",
+            {"body": "改一下分工", "mode": "queued"}, self.owner_key)
+        self.assertEqual(status, 409)
+        self.assertIn("coordinator tasks do not accept follow-up",
+                      body["error"])
+        status, body = self._req(
+            "POST", "/tasks/" + coord["id"] + "/thread/message",
+            {"body": "改一下分工", "mode": "queued"}, self.owner_key)
+        self.assertEqual(status, 409)
+        self.assertIn("coordinator tasks do not accept follow-up",
+                      body["error"])
+
+    def test_followup_to_plain_task_ok(self):
+        status, task = self._create_task()
+        self.assertEqual(status, 201)
+        status, _body = self._req(
+            "POST", "/tasks/" + task["id"] + "/followups",
+            {"body": "继续", "mode": "queued"}, self.owner_key)
+        self.assertEqual(status, 201)
+        status, body = self._req(
+            "POST", "/tasks/" + task["id"] + "/thread/message",
+            {"body": "继续", "mode": "queued"}, self.owner_key)
+        self.assertEqual(status, 201)
+
 
 if __name__ == "__main__":
     unittest.main()