fix(server): prevent SSE disconnect from crashing inspector proxy#1523
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syf2211 wants to merge 1 commit into
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fix(server): prevent SSE disconnect from crashing inspector proxy#1523syf2211 wants to merge 1 commit into
syf2211 wants to merge 1 commit into
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When the browser closes or replaces an SSE session, stderr forwarding and mcpProxy could still call SSEServerTransport.send() after the stream was torn down, throwing an unhandled 'Not connected' error. - Add safe client send helper that ignores disconnected SSE sessions - Remove proxy session maps and stdio stderr listeners on client close - Chain cleanup after mcpProxy onclose for /stdio and /sse routes Fixes modelcontextprotocol#1014
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Summary
Prevent the inspector proxy from crashing with an unhandled
Not connectederror when an SSE client disconnects or is replaced (e.g. browser refresh, multiple tabs, or rapid reconnects).Motivation
Fixes #1014. When the browser closes an SSE session,
SSEServerTransport.send()throws if the stream is already torn down. The stdio stderr forwarder andmcpProxycould still callsend()on in-flight server messages, producing an unhandled rejection that crashes the inspector process.Unlike Streamable HTTP, the legacy
/stdioand/sseroutes also never removed stale entries from the proxy session maps on client disconnect.Changes
sessionRegistryhelpers:sendToClientSafe()— catches disconnected SSE sends instead of crashingremoveSession()— clears proxy session mapschainOnClose()— runs cleanup before existingmcpProxyteardown/stdio: use safe sends for stderr notifications; remove stderr listener and session maps on client close/sse: remove session maps on client closemcpProxy: route client-bound sends throughsendToClientSafeTests
cd server && npm run build— passcd server && npm test— 3/3 passnpm run prettier-check— passNotes
"Not connected"message, consistent with other MCP transports.