fix(host-agent): align MCP integration with mcp SDK 1.28.1 realities

Three final-review deviations closed:

I1 (session-end release): mcp SDK 1.28.1 exposes no per-session
shutdown callback (only a server-level lifespan). Lower the
McpBusyTracker default TTL from 60s to 20s and update spec §6.5,
Q5/R3, D9, and docs/MCP_INTEGRATION.md concurrency section to
document the TTL-only recovery path. 20s is short enough to recover
within one 30s heartbeat interval but long enough that an active
session does not lose its lease during normal operator pauses.

I2 (JSON-RPC error shape): FastMCP Tool.run wraps every non-
UrlElicitationRequiredError exception (including McpError with typed
ErrorData) into ToolError, which the lowlevel call_tool handler
serializes as CallToolResult(isError=true, content=[TextContent(...)]).
There is no public path that surfaces JSON-RPC -32000 with structured
data.busy_owner from a tool call site. Update spec §7 error matrix
and docs/MCP_INTEGRATION.md error table to document the actual wire
shape; busy_owner now lives in the text content.

I3 (typing): mcp_server: Any = None -> FastMCP | None = None via
TYPE_CHECKING, keeping the mcp import lazy (matches precedent
elsewhere in the codebase) while adding static type checking at the
create_console_app boundary.

Tests added (4):
- test_default_ttl_is_20_seconds — locks I1's new default TTL
- test_default_ttl_recovers_dead_session_within_one_window — locks
  I1's recovery semantics (lease sweeped on next read after 20s)
- test_busy_error_wire_shape_is_calltoolresult_iserror — pins I2's
  wire envelope via Tool.run + lowlevel Server._make_error_result
- test_busy_error_text_includes_cloud_assignment_owner — same for
  the cloud_assignment busy_owner branch

Full non-integration suite: 697 passed / 54 deselected (was 693 / 54).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/superpowers/specs/2026-07-21-host-agent-mcp-server-design.md

@@ -38,7 +38,7 @@
 | D6 | 设备状态映射 = 走 `_device_display_status()` 同款逻辑 | 避免"所有连上的设备看起来都 busy" |
 | D7 | Cloud worker 与 MCP server 在同一 host-agent 进程并存 | 不互斥，共享 `DeviceManager` |
 | D8 | Cloud ↔ MCP 协调 = 心跳上报 `mcp_busy_device_ids`，cloud scheduler 跳过 | 心跳 schema 扩展，cloud 侧 _matches() 一处改动 |
-| D9 | MCP session 级 lazy acquire 锁，60s TTL 兜底 | session_id 来自 FastMCP 上下文 |
+| D9 | MCP session 级 lazy acquire 锁，20s TTL 兜底（mcp SDK 1.28.1 无 session-end callback，见 §6.5） | session_id 来自 FastMCP 上下文 |
 | D10 | Skill catalog 工具 MVP 不暴露，保留 `create_mcp_server(skill_catalog_store=...)` 参数化挂载点 | 未来可加 mutating 工具 |
 | D11 | `wait_until_usable` 方法实现 + 单测，但调用方不接入 | 预留能力，MVP 全部 fail-fast |
 | D12 | `tool_handlers(manager)` 改为必传 | 已 grep 确认无调用方依赖 None 默认，根治 `DeviceNotFoundError` 类静默回退地雷 |
@@ -102,7 +102,7 @@ class McpDeviceLease:
     last_seen_at: datetime
 
 class McpBusyTracker:
-    def __init__(self, *, ttl_seconds: float = 60.0, now=None) -> None: ...
+    def __init__(self, *, ttl_seconds: float = 20.0, now=None) -> None: ...
     def acquire(self, device_id: str, session_id: str) -> bool: ...
     def renew(self, device_id: str, session_id: str) -> bool: ...
     def release(self, session_id: str) -> list[str]: ...
@@ -258,32 +258,44 @@ run_async() 主循环启动（行为不变）：
 ### 6.5 Session 结束 / TTL 过期
 
 ```
-正常：Hermes 主动断开 → FastMCP 触发 session shutdown callback
-      → mcp_busy_tracker.release(session_id) → 该 session 持有的所有 lease 释放
-      → 下次心跳 payload 不再包含这些 device_id → cloud 重新视为 idle
+正常：Hermes 主动断开 → mcp SDK 1.28.1 没有 per-session shutdown hook
+      → 该 session 的 lease 进入 TTL 倒计时
+      → 20s TTL 到期 → 下次 busy_device_ids() 或 snapshot() 调用时 lazy sweep
+      → lease 清理 → 下次心跳 payload 不再包含 → cloud 重新视为 idle
 
-异常：Hermes 崩溃 / 网络断 → 无 shutdown callback
-      → 60s TTL 到期 → 下次 busy_device_ids() 或 snapshot() 调用时 lazy sweep
+异常：Hermes 崩溃 / 网络断 → 同上，无 shutdown callback
+      → 20s TTL 到期 → 下次 busy_device_ids() 或 snapshot() 调用时 lazy sweep
       → lease 清理 → 下次心跳 payload 不再包含 → cloud 重新视为 idle
 ```
 
+**Implementation note (2026-07-21 fix wave):** mcp SDK 1.28.1 exposes
+only a server-level `lifespan` hook; `ServerSession.__aexit__` and
+`StreamableHTTPSessionManager` do not surface a per-session
+shutdown callback. The spec originally described a release-on-clean-
+disconnect path that the SDK cannot deliver today. The fallback is
+the 20-second TTL sweep — short enough that a normal heartbeat
+interval (30s) catches the recovery before the cloud scheduler
+notices, long enough that an actively-busy session does not lose its
+lease during normal operator pauses. Explicit release on session end
+remains a future enhancement if/when the SDK exposes the hook.
+
 ## 7. Error Handling Matrix
 
 | # | 触发条件 | 返回语义 | 备注 |
 |---|---|---|---|
 | 1 | `Authorization` 缺失/不匹配 | HTTP 401 + `WWW-Authenticate: Bearer` + JSON `{"error":"invalid token"}` | 不写失败日志；首次成功鉴权写 INFO |
-| 2 | Cloud 占用目标设备 | JSON-RPC `-32000` + `"device X is busy (held by cloud assignment)"` + `data.busy_owner = "cloud_assignment"` | DEBUG 日志 |
-| 3 | 另一 MCP session 占用 | JSON-RPC `-32000` + `"device X is busy (held by another MCP session)"` + `data.busy_owner = "mcp_session:<prefix>"` | DEBUG 日志 |
-| 4 | `device_id` 不存在 | JSON-RPC `-32602` + `"unknown device: X"` | 复用 `call_with_semantic_errors` |
-| 5 | 工具底层异常 | JSON-RPC `-32000` + 原异常 message | WARNING + exc_info |
+| 2 | Cloud 占用目标设备 | `CallToolResult(isError=true, content=[TextContent("device phone-1 is busy (held by cloud assignment)")])` | DEBUG 日志 |
+| 3 | 另一 MCP session 占用 | `CallToolResult(isError=true, content=[TextContent("device phone-1 is busy (held by mcp_session:<8-char-prefix>)")])` | DEBUG 日志 |
+| 4 | `device_id` 不存在 | `CallToolResult(isError=false)` + JSON `{"ok": false, "error": "device not found: phone-1"}` | 复用 `call_with_semantic_errors`；语义错误不抛 |
+| 5 | 工具底层异常 | `CallToolResult(isError=true, content=[TextContent("Error executing tool <name>: <orig-msg>")])` | WARNING + exc_info |
 | 6 | Cloud assignment 启动前命中 MCP 占用 | `AssignmentExecutionResult(status="failed", failure_reason="device held by active MCP session")` | INFO 一次 |
 | 7 | Token 文件损坏 JSON | host-agent 启动失败，stderr 提示 | 不静默重新生成 |
 | 8 | Token 文件不可写 | host-agent 启动失败 | 同上 |
-| 9 | MCP session 异常断开 | lease 进入 TTL 倒计时 | 60s 后 lazy sweep |
+| 9 | MCP session 异常断开 | lease 进入 TTL 倒计时 | 20s 后 lazy sweep |
 | 10 | TTL 过期瞬间 Hermes 重连 | renew 容忍边界：session_id 匹配 → 重新 acquire 而非报错 | 无感 |
 | 11 | 同 session 并发不同设备 | 各自独立 acquire | per-device 设计 |
 | 12 | 同 session 并发同一设备 | 第一个 acquire；第二个 renew（同 session_id） | 并发 safe |
-| 13 | FastMCP 提取不到 session_id | JSON-RPC `-32001` + `"cannot determine MCP session"` | ERROR + exc_info |
+| 13 | FastMCP 提取不到 session_id | `CallToolResult(isError=true, content=[TextContent("cannot determine MCP session")])` | ERROR + exc_info |
 | 14 | host-agent 关停时有 active MCP session | lease 随进程退出消失 | 不需显式清理 |
 
 ### 错误返回格式
@@ -292,17 +304,32 @@ run_async() 主循环启动（行为不变）：
 {
   "jsonrpc": "2.0",
   "id": "<request-id>",
-  "error": {
-    "code": -32000,
-    "message": "device phone-1 is busy (held by cloud assignment)",
-    "data": {
-      "device_id": "phone-1",
-      "busy_owner": "cloud_assignment"
-    }
+  "result": {
+    "content": [
+      {
+        "type": "text",
+        "text": "device phone-1 is busy (held by cloud assignment)"
+      }
+    ],
+    "isError": true
   }
 }
 ```
 
+**Implementation note (2026-07-21 fix wave):** mcp SDK 1.28.1's
+`Tool.run` wraps every non-`UrlElicitationRequiredError` exception
+(including `McpError` with a typed `ErrorData`) into `ToolError`.
+The lowlevel `call_tool` handler then serializes any exception as
+`CallToolResult(isError=true, content=[TextContent(message)])` via
+`_make_error_result`. There is no public path that surfaces JSON-RPC
+`-32000` with a structured `data.busy_owner` field from a tool call
+site — the SDK's wire contract for tool errors is the `isError=true`
+flag plus text content. The busy-owner value lives in the text
+content (truncated session_id for `mcp_session:` collisions, full
+string for `cloud_assignment`). Unknown-device and other semantic
+errors are returned as normal `ok=False` payloads inside a successful
+`CallToolResult(isError=false)` (see `api/mcp.py::call_with_semantic_errors`).
+
 ## 8. Testing Strategy
 
 ### 8.1 单元测试
@@ -376,13 +403,13 @@ run_async() 主循环启动（行为不变）：
 - **Q2**：`mcp-token` CLI 是否需要鉴权？→ MVP 不鉴权，假定能访问宿主机的操作者可信（与 `setup` 子命令同款）。后续可加 `--password` 校验 local_account。
 - **Q3**：MCP 工具调用是否需要 wall-clock 超时？→ MVP 不加，依赖底层超时；如有"Hermes 调用挂死"报告再加。
 - **Q4**：心跳扩展是 Alembic migration 还是仅 schema 字段？→ MVP 仅 transient 字段（heartbeat 接收 → scheduler 用 → 丢弃），无需 migration。
-- **Q5（待实测）**：60s TTL 是否合适？→ 实测后调整。太短容易误释放正常 session 的锁；太长 Hermes 崩溃后设备不可用窗口大。
+- **Q5（已答，2026-07-21 fix wave）**：TTL 从 60s 降到 20s，因为 mcp SDK 1.28.1 没有 per-session shutdown callback（见 §6.5）。20s 仍能容许正常 operator 暂停，但能在一次 30s 心跳窗口内回收崩盘 session 的锁；新 `test_default_ttl_is_20_seconds` 和 `test_default_ttl_recovers_dead_session_within_one_window` 锁定该值。如有"Hermes 长操作横跨 20s 静默"报告再调高。
 
 ## 11. Risks
 
 - **R1**：Cloud 心跳窗口期（30s）冲突。缓解：AssignmentExecutor 启动前 fail-fast。残留：cloud 可能基于过期心跳派任务、host-agent fail、cloud 重试——浪费 attempt 配额。**接受**。
 - **R2**：Hermes 长时间占用设备导致 cloud 任务反复 fail。MVP 无自动缓解；用户手动管控；未来启用 `wait_until_usable`。**接受**。
-- **R3**：Hermes 崩溃后 60s 内设备不可用。TTL 兜底但窗口存在。**接受，记入 Q5**。
+- **R3**：Hermes 崩溃后 ≤20s 设备不可用（TTL 兜底，但窗口存在）。窗口仍 ≤30s 心跳间隔，cloud 侧下次心跳能学到。**接受，记入 Q5**。
 - **R4（已消除）**：`tool_handlers` 签名改动影响面。Grep 确认 0 调用方依赖 None 默认。
 - **R5**：FastMCP `session_id` 提取依赖 `mcp` SDK 内部 API。缓解：e2e 测试覆盖；SDK 升级 CI 能及时暴露。
 - **R6**：`mcp` SDK 需作为 device-host-agent 直接依赖（目前通过 Runtime 传递）。需加进 `apps/device-host-agent/pyproject.toml`（与 `filelock` 直接化先例一致）。