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refactor(mcp): make MCP test reuse the shared Box session (near-instant tests) (#2304)

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* refactor(mcp): make MCP test reuse the shared Box session instead of a per-test session

Testing an MCP server (config-page "test" button) previously spun up a fresh
isolated mcp-test-<uuid> Box session every time: cold-start the container, run
the dependency bootstrap, probe, then tear the whole session down. That is slow
(tens of seconds) and, on an already-hosted server, wasteful — the server is
already running in the shared session.

Change the test to reuse the shared session / live process:

- _build_box_session_id: transient tests now use mcp-shared, the same Box
  session as live servers, so a test reuses the running container (and, for an
  existing server, its live managed process) instead of a cold per-test session.
- cleanup_session: a transient test no longer deletes the whole session (which
  under the shared model would kill every other MCP server in the container). It
  stops only its own process_id, exactly like a live server. Isolation is now at
  the process level (distinct process_id per server/test), not the session level.
- test_mcp_server (persisted server): reuse the live connection with a real
  list_tools refresh/probe; only fall back to a full start() when there is no
  live connection to probe or the refresh fails, instead of an ERROR->start()
  rebuild.

Trade-off: a failing test now shares the container with live servers rather than
a throwaway session. Accepted deliberately in favour of near-instant tests;
process-level isolation keeps a test from stopping another server's process.

* chore(deps): pin langbot-plugin 0.4.9 for the nsjail RLIMIT_AS node/npx MCP fix

---------

Co-authored-by: dadachann <185672915+dadachann@users.noreply.github.com>
This commit is contained in:
Hyu
2026-07-03 13:14:14 +08:00
committed by GitHub
parent a2655e16f8
commit 9a8cdde86c
6 changed files with 49 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files
pyproject.toml
+1 -1
View File
@@ -70,7 +70,7 @@ dependencies = [
"chromadb>=1.0.0,<2.0.0",
"qdrant-client (>=1.15.1,<2.0.0)",
"pyseekdb==1.1.0.post3",
"langbot-plugin==0.4.8",
"langbot-plugin==0.4.9",
"asyncpg>=0.30.0",
"line-bot-sdk>=3.19.0",
"matrix-nio>=0.25.2",
src/langbot/pkg/api/http/service/mcp.py
+14 -2
View File
@@ -188,10 +188,22 @@ class MCPService:
persisted_session = runtime_mcp_session
async def _refresh_and_report() -> None:
if persisted_session.status == MCPSessionStatus.ERROR:
# Testing a persisted server should REUSE its live shared-session
# process, not rebuild it. Try a lightweight refresh (a real
# list_tools probe over the existing connection) first; only fall
# back to a full start() when the session has no live connection
# to probe (never connected, or the process is actually gone).
needs_start = persisted_session.status == MCPSessionStatus.ERROR or persisted_session.session is None
if needs_start:
await persisted_session.start()
else:
await persisted_session.refresh()
try:
await persisted_session.refresh()
except Exception:
# The live connection was stale/dropped: reconnect once
# (reusing the live managed process where possible) and
# re-probe, instead of reporting a false failure.
await persisted_session.start()
# Surface the discovered tools so the config page can render them
# even for an already-hosted server.
ctx.metadata['runtime_info'] = persisted_session.get_runtime_info_dict()
src/langbot/pkg/provider/tools/loaders/mcp.py
+8 -5
View File
@@ -986,11 +986,14 @@ class RuntimeMCPSession:
return self._box_stdio_runtime.uses_box_stdio()
def _build_box_session_id(self) -> str:
# Transient test sessions get their own isolated Box session so a
# failing/short-lived test can never disturb the shared session that
# hosts live, already-connected MCP servers.
if self.is_transient:
return f'mcp-test-{self.server_uuid}'
# Both live servers and transient config-page tests share ONE Box
# session ('mcp-shared'). A test therefore reuses the already-running
# container (and, for an existing server, its live managed process)
# instead of paying a full per-test session cold-start + dependency
# bootstrap. Isolation between a test and the live servers is provided
# at the *process* level: each server/test has its own process_id and a
# test only ever stops its own process_id (see cleanup_session), so it
# never disturbs another server's process or the shared session itself.
return 'mcp-shared'
def _rewrite_path(self, path: str, host_path: str | None) -> str:
src/langbot/pkg/provider/tools/loaders/mcp_stdio.py
+10 -6
View File
@@ -370,16 +370,20 @@ class BoxStdioSessionRuntime:
workspace = self._build_workspace(host_path=None)
# Transient test sessions own their isolated Box session, so tear the
# whole session down rather than leaking it. This cannot affect live
# servers because they live in the separate shared session.
# Transient config-page tests now share the same 'mcp-shared' Box
# session as live servers, so we must NOT tear the session down here —
# that would kill every other MCP server in the container. A test is
# isolated at the process level: it ran under its own process_id, so we
# stop only that process, exactly like a live server does below. The
# shared session and all other servers' live processes are untouched.
# (Staged per-test workspace files are still cleaned up.)
if getattr(self.owner, 'is_transient', False):
try:
await workspace.cleanup()
await workspace.stop_managed_process(self.process_id)
except Exception as exc:
self.ap.logger.warning(
f'MCP server {self.server_name}: failed to delete transient test session '
f'{self.owner._build_box_session_id()}: {type(exc).__name__}: {exc}'
f'MCP server {self.server_name}: failed to stop transient test process '
f'process_id={self.process_id}: {type(exc).__name__}: {exc}'
)
await self._cleanup_staged_workspace()
return
tests/unit_tests/provider/test_mcp_box_integration.py
+12 -7
View File
@@ -639,10 +639,13 @@ class TestGetRuntimeInfoDict:
assert info['box_session_id'] == 'mcp-shared'
assert info['box_enabled'] is True
def test_transient_test_session_is_isolated_from_shared(self, mcp_module):
"""A transient test session (config-page "test", no persisted UUID)
must NOT share the live "mcp-shared" Box session. Regression: a failing
test churned the shared session and tore down healthy live servers."""
def test_transient_test_shares_session_but_isolated_by_process(self, mcp_module):
"""A transient config-page "test" now shares the same 'mcp-shared' Box
session as live servers (so a test reuses the running container / live
process instead of a cold per-test session bootstrap). Isolation is at
the PROCESS level: the test runs under its own process_id and only ever
stops that process_id, so it cannot disturb another server's live
process or the shared session itself."""
ap = _make_ap()
ap.box_service.available = True
transient = _make_session(
@@ -670,10 +673,12 @@ class TestGetRuntimeInfoDict:
)
assert transient.is_transient is True
assert live.is_transient is False
# Isolated session id for the test, shared for the live server.
assert transient._build_box_session_id() == 'mcp-test-gen-uuid-123'
# Both share ONE Box session ...
assert transient._build_box_session_id() == 'mcp-shared'
assert live._build_box_session_id() == 'mcp-shared'
assert transient._build_box_session_id() != live._build_box_session_id()
assert transient._build_box_session_id() == live._build_box_session_id()
# ... but are isolated by distinct process_ids within that session.
assert transient._box_stdio_runtime.process_id != live._box_stdio_runtime.process_id
def test_stdio_session_refuses_when_box_unavailable(self, mcp_module):
"""Policy: when Box is configured but unavailable (disabled in config
uv.lock
Generated
+4 -4
View File
@@ -2123,7 +2123,7 @@ requires-dist = [
{ name = "ebooklib", specifier = ">=0.18" },
{ name = "gewechat-client", specifier = ">=0.1.5" },
{ name = "html2text", specifier = ">=2024.2.26" },
{ name = "langbot-plugin", specifier = "==0.4.8" },
{ name = "langbot-plugin", specifier = "==0.4.9" },
{ name = "langchain", specifier = ">=1.3.9" },
{ name = "langchain-core", specifier = ">=1.3.3" },
{ name = "langchain-text-splitters", specifier = ">=1.1.2" },
@@ -2187,7 +2187,7 @@ dev = [
[[package]]
name = "langbot-plugin"
version = "0.4.8"
version = "0.4.9"
source = { registry = "https://pypi.org/simple" }
dependencies = [
{ name = "aiofiles" },
@@ -2208,9 +2208,9 @@ dependencies = [
{ name = "watchdog" },
{ name = "websockets" },
]
sdist = { url = "https://files.pythonhosted.org/packages/7f/f5/1b417a48d329f959a261eaf9a37b26197f18081d2b6f0ef3e4bbab687b81/langbot_plugin-0.4.8.tar.gz", hash = "sha256:e9614be248acf352acb9430d9e154e0abae981575de16812f68282c92a4e42d8", size = 334076, upload-time = "2026-07-03T04:15:28.233Z" }
sdist = { url = "https://files.pythonhosted.org/packages/54/52/f85939d3be929696dc5f9f3369f18bd6652981a8985c6e6f0dfe48e04f75/langbot_plugin-0.4.9.tar.gz", hash = "sha256:1cc2882f1be96cd52be6c392c3925e44cf785c97c10f82a321339636da318c6e", size = 334682, upload-time = "2026-07-03T04:57:42.813Z" }
wheels = [
{ url = "https://files.pythonhosted.org/packages/40/21/46bfa911ab27d6856a3b4363805c4bb8a657500cbc12e1e719d0b3b349dc/langbot_plugin-0.4.8-py3-none-any.whl", hash = "sha256:87c12d9d5579b0ab4dc43c9e559b4d15d7387db8c8b52d476cf27a3de74aedf5", size = 221244, upload-time = "2026-07-03T04:15:27.087Z" },
{ url = "https://files.pythonhosted.org/packages/47/12/1cf535377a81cf01607bbee5e3f4745a8c9f6dbb561887467001a182a533/langbot_plugin-0.4.9-py3-none-any.whl", hash = "sha256:693225a089ba38bc8d0b58d9e0fdf07b027b5be6b5e858cf7b4e56d095b68ba5", size = 221722, upload-time = "2026-07-03T04:57:41.578Z" },
]
[[package]]