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Hyu
a2655e16f8
* fix(mcp): survive transient WS transport drops for Box stdio MCP servers A Box-backed stdio MCP server (e.g. pab1it0/prometheus) would periodically error on the frontend with Box managed process exited unexpectedly / Failed after 4 attempts once the session had been alive for a while. Root cause: the managed MCP process lives in the Box runtime and SURVIVES a WebSocket transport drop, but _lifecycle_loop treated any monitor completion as a fatal process death. It then ran the finally-block cleanup — which STOPS the still-healthy managed process — and did a full 4-attempt exponential backoff rebuild. Under an occasionally-stalled single-worker event loop the mcp websocket client misses a ping/pong, the transport drops, and this self-inflicted teardown loop is what the user sees. Fixes: - _lifecycle_loop: when the health monitor completes, re-check the real managed-process state. If the process is still running, the transport merely dropped: raise an internal _TransportReconnect signal instead of Box managed process exited unexpectedly. - _lifecycle_loop_with_retry: handle _TransportReconnect as a free, uncounted reconnect (does not consume the fatal retry budget), so a long-lived session survives arbitrarily many transient drops. - finally-block: gate managed-process teardown on a _preserve_managed_process flag so a transport-only reconnect closes just the WS, not the process. - BoxStdioSessionRuntime.initialize: reuse an already-running managed process instead of stopping+rebuilding it (which also re-ran the slow dependency bootstrap); only (re)start when none is running. Adds _managed_process_is_running() helper. Pairs with langbot-plugin-sdk fix adding a server-driven WS heartbeat to the managed-process relay, which prevents most drops in the first place. * style(mcp): ruff format * chore(deps): pin langbot-plugin 0.4.8 for the managed-process WS heartbeat fix --------- Co-authored-by: dadachann <185672915+dadachann@users.noreply.github.com>