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Hyu
ed9343c686
A node/npx stdio MCP server (e.g. firecrawl-mcp via npx -y) failed on first connect with Connection closed / Failed after 4 attempts, even though the process was fine. An npx cold start downloads+installs the package before the server can answer the MCP handshake (measured ~27s for a simple official server; longer for heavier ones). The old code attached the WS and called session.initialize() the instant the process was started, so the handshake ran before the process could answer and failed; the outer lifecycle retry then rebuilt the process, churning it in a loop. Verified decisively: attaching + initialize() against a mid-cold-start process times out on attempt 1 (process still installing) but SUCCEEDS at t+0.6s on attempt 2 once the process is ready. So the fix is to retry the handshake in place, not to rebuild the process. Changes (mcp_stdio.initialize): - Start the managed process ONCE, then loop attach WS -> ClientSession -> initialize() within the startup_timeout budget, tearing down each failed attempt cleanly, until the handshake succeeds or the budget elapses. A successful transport/session is transferred into the owner exit stack via a small _TransferredStack adapter. - Bound each attempt with asyncio.wait_for(initialize, _HANDSHAKE_ATTEMPT_TIMEOUT_SEC=10s) so a cold-starting process fails fast and retries instead of hanging until the transport drops. - Stop retrying ONLY when the process has DEFINITIVELY exited: new _managed_process_has_exited() (checks EXITED status) replaces the previous not-_managed_process_is_running() test, which false-negatived on a just-spawned process that had not yet reported RUNNING and made the loop bail to the outer rebuild path (relay then rejected the early re-attach with HTTP 400). Adds a unit test that fails the first two handshakes with the process alive and asserts the loop retries to success while starting the process exactly once. Co-authored-by: dadachann <185672915+dadachann@users.noreply.github.com>