云端 goal/merge/review 三事件：goal 循环 + PR 事件通知

此前 goal-unmet/merge-failed/review-requested 只有允许列表，
云端没有生产者（概念只在本地 host.py）。本轮给三者接真生产者：
- goal：POST /tasks 接受 goal/verify_command/goal_max_rounds
  （迁移补列，SQLite 与 Postgres 两支）；带 verify_command 的
  任务走 host.py goal 循环（Local/Docker 执行器 goal_task，
  turn→验测→喂回重试，缺省 3 轮）；达标 completed，未达标
  failed 且只发 goal-unmet、不重复发 failed；goal 模式下 worker
  级重试/fallback 关闭，同任务 /retry 会撞 host 任务名已存在
  （已在文档写明，须新建任务）；CloudExecutor 无 goal 概念，
  如实失败不降级
- review-requested：POST /tasks/{id}/pr 建 PR 成功时发
  （payload 含 pr_url/pr_number）
- merge-failed：PR 落盘（push/建 PR）失败 502 时发（payload
  含 step/error），任务保持 merged、可重调 /pr；跳过时不发
测试：host 29、cloud 469 全过。

cloud/tests/test_worker.py

@@ -223,6 +223,157 @@ class WorkerTestCase(unittest.TestCase):
             server.server_close()
             thread.join(timeout=5)
 
+    # -- goal 模式 -------------------------------------------------------
+    def _set_goal(self, task_id, verify="test -f x", goal=None,
+                  rounds=None):
+        conn = sqlite3.connect(self.db_path)
+        try:
+            conn.execute(
+                "UPDATE tasks SET verify_command = ?, goal = ?,"
+                " goal_max_rounds = ? WHERE id = ?",
+                (verify, goal, rounds, task_id))
+            conn.commit()
+        finally:
+            conn.close()
+
+    def test_goal_met_notifies_completed(self):
+        """goal 达标：任务 completed，发 completed（不发 goal-unmet）。"""
+        import http.server
+        import threading
+
+        requests = []
+
+        class Handler(http.server.BaseHTTPRequestHandler):
+            def do_POST(self):
+                length = int(self.headers.get("Content-Length") or 0)
+                body = self.rfile.read(length) if length else b""
+                requests.append(json.loads(body.decode("utf-8")))
+                self.send_response(200)
+                self.send_header("Content-Length", "2")
+                self.end_headers()
+                self.wfile.write(b"{}")
+
+            def log_message(self, *args):
+                pass
+
+        server = http.server.ThreadingHTTPServer(
+            ("127.0.0.1", 0), Handler)
+        thread = threading.Thread(
+            target=server.serve_forever, daemon=True)
+        thread.start()
+        try:
+            from cloud.push import create_subscription
+            url = "http://127.0.0.1:%d/hook" % server.server_address[1]
+            create_subscription(
+                self.db_path, "p1", "user-1", "webhook", url, "instant")
+            _insert_task(self.db_path, "A")
+            self._set_goal("A")
+            calls = []
+
+            def goal_runner(cmd):
+                calls.append(list(cmd))
+                return SimpleNamespace(
+                    returncode=0,
+                    stdout="round 1: turn=completed verify_rc=0 "
+                           "verify_out=ok\ngoal met after rounds\n",
+                    stderr="")
+
+            worker = self._worker(runner=goal_runner)
+            results = worker.run_all()
+            self.assertEqual(
+                [r["status"] for r in results], ["completed"])
+            self.assertIn("goal", calls[0])
+            self.assertEqual(len(requests), 1)
+            self.assertEqual(requests[0]["event_type"], "completed")
+        finally:
+            server.shutdown()
+            server.server_close()
+            thread.join(timeout=5)
+
+    def test_goal_unmet_notifies_only_goal_unmet(self):
+        """goal 未达：任务 failed，只发 goal-unmet，不重复发 failed。"""
+        import http.server
+        import threading
+
+        requests = []
+
+        class Handler(http.server.BaseHTTPRequestHandler):
+            def do_POST(self):
+                length = int(self.headers.get("Content-Length") or 0)
+                body = self.rfile.read(length) if length else b""
+                requests.append(json.loads(body.decode("utf-8")))
+                self.send_response(200)
+                self.send_header("Content-Length", "2")
+                self.end_headers()
+                self.wfile.write(b"{}")
+
+            def log_message(self, *args):
+                pass
+
+        server = http.server.ThreadingHTTPServer(
+            ("127.0.0.1", 0), Handler)
+        thread = threading.Thread(
+            target=server.serve_forever, daemon=True)
+        thread.start()
+        try:
+            from cloud.push import create_subscription
+            url = "http://127.0.0.1:%d/hook" % server.server_address[1]
+            create_subscription(
+                self.db_path, "p1", "user-1", "webhook", url, "instant")
+            _insert_task(self.db_path, "A")
+            self._set_goal("A")
+
+            def unmet_runner(cmd):
+                return SimpleNamespace(
+                    returncode=0,
+                    stdout="round 1: turn=completed verify_rc=1 "
+                           "verify_out=file missing\n"
+                           "goal unmet after rounds\n",
+                    stderr="")
+
+            worker = self._worker(runner=unmet_runner)
+            results = worker.run_all()
+            self.assertEqual([r["status"] for r in results], ["failed"])
+            self.assertEqual(len(requests), 1)
+            self.assertEqual(requests[0]["event_type"], "goal-unmet")
+            self.assertIn("file missing",
+                          requests[0]["payload"]["error"])
+        finally:
+            server.shutdown()
+            server.server_close()
+            thread.join(timeout=5)
+
+    def test_goal_mode_runs_once_despite_retries(self):
+        """goal 模式只跑一次：循环内部已多轮重试，worker 级重试
+        不再叠加（同任务重跑会撞 host 任务名已存在）。"""
+        _insert_task(self.db_path, "A")
+        self._set_goal("A")
+        calls = []
+
+        def counting(cmd):
+            calls.append(cmd)
+            return SimpleNamespace(
+                returncode=0,
+                stdout="round 1: turn=completed verify_rc=1 "
+                       "verify_out=nope\ngoal unmet after rounds\n",
+                stderr="")
+
+        worker = self._worker(runner=counting, max_retries=2)
+        results = worker.run_all()
+        self.assertEqual(len(calls), 1)
+        self.assertEqual(results[0]["status"], "failed")
+
+    def test_cloud_executor_goal_unsupported(self):
+        """cloud 执行器没有 goal 概念：goal 任务如实失败，
+        不静默降级成普通 dispatch。"""
+        from cloud.sandbox import CloudExecutor
+        _insert_task(self.db_path, "A")
+        self._set_goal("A")
+        worker = self._worker(executor=CloudExecutor())
+        results = worker.run_all()
+        self.assertEqual(results[0]["status"], "failed")
+        self.assertIn("不支持 goal", results[0]["error"])
+
     # -- 取消 ------------------------------------------------------------
     def test_cancel_queued_task_marks_interrupted(self):
         _insert_task(self.db_path, "A")