逐任务真实成本：上游用量事件 + 价目表计价

此前每任务只记一条 estimated（字符数/4，金额为空），注释称
host 协议不暴露真实 token 数。本轮实测推翻了该前提：
- account/usage/read 在中继上是死的（要求 ChatGPT 账号登录），
  不是来源，已在 cost.py docstring 写明死胡同
- app-server 每上游补全发 thread/tokenUsage/updated，last 是该次
  补全的用量；中继 5 调用回合实测 last 之和等于最后 total
  （input/output/cached/reasoning 四路都对得上）

实现：host.py run_turn 从事件窗口按 threadId+turnId 汇总用量，
重试/goal 各轮累加，dispatch/run JSON 与 goal 用量行透传；
sandbox 三路解析（dispatch JSON 解析改用完整 stdout，顺带修
了长 text 下 failed 被误判 completed 的潜 bug）；worker 每任务
记一条 actual（重试/fallback 用量累加进同一条），无用量时回落
estimated；cost.py 价目表（默认 OpenAI 挂牌价，env 可覆盖，
无价模型 usd 记 None、报表进 unpriced_actual_tokens 而非 0 美元），
cost_records 加 cached_input_tokens 列（SQLite/PG 两支迁移）；
报表与按天行新增 cached_input_tokens/unpriced_actual_tokens。
测试：host 32、cloud 483 全过。

cloud/tests/test_worker.py

@@ -374,6 +374,75 @@ class WorkerTestCase(unittest.TestCase):
         self.assertEqual(results[0]["status"], "failed")
         self.assertIn("不支持 goal", results[0]["error"])
 
+    # -- 成本：真实用量 --------------------------------------------------
+    def test_cost_actual_from_usage(self):
+        """执行器带回用量时记 actual：token 全是实测值，usd 按
+        价目表算（(1000-400)*2 + 400*0.10 + 100*10 = 2240 微美元）。"""
+        _insert_task(self.db_path, "A")
+        usage = {"input_tokens": 1000, "cached_input_tokens": 400,
+                 "cache_write_input_tokens": 0, "output_tokens": 100,
+                 "reasoning_output_tokens": 20, "total_tokens": 1100,
+                 "completions": 1}
+
+        def runner(cmd):
+            return SimpleNamespace(
+                returncode=0,
+                stdout=json.dumps({"status": "completed", "text": "done",
+                                   "usage": usage}),
+                stderr="")
+
+        worker = self._worker(runner=runner, model="gpt-6.1-sol")
+        results = worker.run_all()
+        self.assertEqual([r["status"] for r in results], ["completed"])
+        from cloud.cost import CostStore
+        report = CostStore(self.db_path).report_by_task("A")
+        self.assertEqual(report["actual_tokens"], 1100)
+        self.assertEqual(report["cached_input_tokens"], 400)
+        self.assertEqual(report["estimated_tokens"], 0)
+        self.assertEqual(report["usd_micros"], 2240)
+        self.assertEqual(report["unpriced_actual_tokens"], 0)
+
+    def test_cost_actual_unpriced_model(self):
+        """无价模型：token 照样记 actual，usd 记 None、报表里
+        进 unpriced_actual_tokens，绝不按 0 美元处理。"""
+        _insert_task(self.db_path, "A")
+        usage = {"input_tokens": 1000, "cached_input_tokens": 0,
+                 "cache_write_input_tokens": 0, "output_tokens": 100,
+                 "reasoning_output_tokens": 0, "total_tokens": 1100,
+                 "completions": 1}
+
+        def runner(cmd):
+            return SimpleNamespace(
+                returncode=0,
+                stdout=json.dumps({"status": "completed", "text": "done",
+                                   "usage": usage}),
+                stderr="")
+
+        worker = self._worker(runner=runner, model="gpt-5.6-sol")
+        results = worker.run_all()
+        self.assertEqual([r["status"] for r in results], ["completed"])
+        from cloud.cost import CostStore
+        report = CostStore(self.db_path).report_by_task("A")
+        self.assertEqual(report["actual_tokens"], 1100)
+        self.assertEqual(report["usd_micros"], 0)
+        self.assertEqual(report["unpriced_actual_tokens"], 1100)
+
+    def test_cost_estimated_when_no_usage(self):
+        """执行器没带回用量时回落字符估算记 estimated（旧行为）。"""
+        _insert_task(self.db_path, "A")
+
+        def runner(cmd):
+            return SimpleNamespace(returncode=0, stdout="plain text",
+                                   stderr="")
+
+        worker = self._worker(runner=runner, model="gpt-6.1-sol")
+        results = worker.run_all()
+        self.assertEqual([r["status"] for r in results], ["completed"])
+        from cloud.cost import CostStore
+        report = CostStore(self.db_path).report_by_task("A")
+        self.assertEqual(report["actual_tokens"], 0)
+        self.assertGreater(report["estimated_tokens"], 0)
+
     # -- 取消 ------------------------------------------------------------
     def test_cancel_queued_task_marks_interrupted(self):
         _insert_task(self.db_path, "A")