next.js

28f96a4f - fix(trace-server): default MCP port to --port + 1 to avoid conflicts (#92831)

fix(trace-server): default MCP port to --port + 1 to avoid conflicts (#92831) ### What? When `--mcp-port` is not explicitly provided to `next internal trace`, the MCP HTTP server now defaults to `--port + 1` (the WebSocket port plus one) instead of the hardcoded value `5748`. The `DEFAULT_WS_PORT` remains `5747`, so when neither flag is passed the behavior is unchanged: WS=5747, MCP=5748. ### Why? Starting the trace server twice with different `--port` values (e.g. to analyze two trace files simultaneously) caused both instances to attempt to bind the same hardcoded MCP port `5748`: ``` Error: MCP port 5748 is already in use. Use --mcp-port to specify a different port. ``` Making the MCP port default relative to the WS port means each invocation with a unique `--port` automatically gets a unique `--mcp-port` without any extra flags. ### How? In `startTurboTraceServerCli`, changed: ```ts const httpPort = mcpPort ?? DEFAULT_MCP_PORT // always 5748 ``` to: ```ts const httpPort = mcpPort ?? wsPort + 1 // e.g. 5748, 6001, 7001, … ``` The now-unused `DEFAULT_MCP_PORT` constant in `turbo-trace-server.ts` was removed. The identical constant in `query-trace.ts` is kept — it is the client-side default for *connecting* to an MCP server and `5748` remains a sensible default there. The `--mcp-port` help text was updated to reflect the dynamic default. <!-- NEXT_JS_LLM_PR --> Co-authored-by: Tobias Koppers <sokra@users.noreply.github.com> Co-authored-by: Claude <noreply@anthropic.com>