* Fix NPX MCP server crash by checking install state instead of timing out
When @playwright/mcp (or any future npx-based built-in server) isn't
already cached, npx tries to download and install it on first invoke.
That can take minutes or hang on a fresh install missing Playwright
system deps. The previous code bounded that wait with
asyncio.wait_for(mcp_manager.connect_server(...), timeout=30), but the
cancellation that wait_for fires on timeout propagates into
mcp.client.stdio.stdio_client's internal anyio task group, which
raises:
RuntimeError: Attempted to exit cancel scope in a different task
than it was entered in
The error fires in a sibling background task (Task exception was never
retrieved) so the surrounding try/except BaseException doesn't catch
it, and the orphaned cancel scope cascades cancellations into other
tasks in the same event loop. Running requests start failing and the
process needs a restart.
Fix: detect whether the package is already cached before invoking
connect_server, instead of trying to bound the connect with a timeout.
A new _is_npx_package_cached helper runs:
npx --no-install <pkg> --version
The --no-install flag makes npx fail fast on a cache miss instead of
downloading, so the probe returns in <500ms either way. If the package
isn't cached, we log a warning with the exact command the user can run
to install it, and skip the server. If it is cached, we call
connect_server normally with no wait_for wrapper, so there's no
cancellation that could enter stdio_client's task group.
This removes the entire bug class instead of papering over it. No
asyncio.wait_for around stdio_client, no shielded-task leak, no
shutdown-time RuntimeError. Verified against current versions
(mcp library on Python 3.14, anyio 4.13.0) with the existing
@playwright/mcp@latest cached, and with a deliberately uncached
package spec to exercise the skip path.
* Make first-run setup explicit when NPX MCP package isn't cached
Per @pewdiepie-archdaemon review on #253:
- src/builtin_mcp.py: expand the skip-server warning into a multi-line
block with Reason/Impact/Fix/Notes lines, so the message stands out
in startup logs and clearly tells the user what to run.
- README.md: add 'Built-in MCP servers (optional setup)' subsection
under Configuration, with the install command and a brief note that
it's optional and skipped if not cached.
