fix: prevent orphaned browser when client disconnects#222
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StdioServerTransport only listens for 'data'/'error' on stdin, so when the parent/client process dies (stdin EOF) nothing tears the server down. The process lingers (often reparented to launchd/init) holding its Chromium, which accumulates over time as stale headless browsers. Additionally, the graceful shutdown handler exits without closing the browser, so even SIGINT/SIGTERM left Chromium to be cleaned up only by Playwright's own exit hooks (racy under process.exit). This change: - adds closeBrowser() to toolHandler and calls it from shutdown(), with a 5s timeout so a hung close can't block exit and a re-entrancy guard - watches process.stdin 'end'/'close' in stdio mode to shut down cleanly when the client/parent goes away Verified: launching a browser then closing the server's stdin now reaps both the server process and its Chromium children (no orphans). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Problem
When running in stdio mode, the server can leave orphaned Chromium processes behind:
StdioServerTransportonly attachesdata/errorlisteners tostdin— it never reacts to stdin reaching EOF. So when the MCP client (or parent process) dies, the server keeps running, frequently reparented tolaunchd/init, still holding its launched browser. These accumulate over time as stale headless browsers eating memory.SIGINT/SIGTERMhandler callsprocess.exit(0)without closing the browser, leaving cleanup to Playwright's own exit hooks, which is racy under an immediateprocess.exit.Fix
closeBrowser()totoolHandler.ts— closes the active browser (if connected) and resets state; safe to call when no browser is open.shutdown()before exit, wrapped inPromise.racewith a 5s timeout so a hung close can't block exit, plus a re-entrancy guard for repeated signals.process.stdinend/closein stdio mode so the server shuts down cleanly when the client/parent goes away. (HTTP--portmode is unaffected — these listeners are only registered on the stdio path.)Verification
Launching a browser via
playwright_navigate, then closing the server's stdin:headless_shellchild processes are reaped — no orphans.All 150 existing tests pass; build is clean.
🤖 Generated with Claude Code