fix(mcp): exit serve process on stdin-close/SIGTERM

src/mcp/server.ts

@@ -32,6 +32,26 @@ export async function startMcpServer(engine: BrainEngine) {
 
   const transport = new StdioServerTransport();
   await server.connect(transport);
+
+  // Exit cleanly when MCP client disconnects (stdin EOF) or on signals.
+  // Without this, orphaned serve processes accumulate and contend for the
+  // PGLite write lock, causing ingest jobs (email-sync) to time out.
+  let shuttingDown = false;
+  const shutdown = (reason: string, code = 0) => {
+    if (shuttingDown) return;
+    shuttingDown = true;
+    process.stderr.write(`[gbrain-serve] shutdown: ${reason}\n`);
+    Promise.resolve(engine.disconnect?.())
+      .catch(() => {})
+      .finally(() => process.exit(code));
+  };
+  process.stdin.on('end', () => shutdown('stdin end'));
+  process.stdin.on('close', () => shutdown('stdin close'));
+  // @ts-ignore — SDK exposes onclose on transport
+  transport.onclose = () => shutdown('transport close');
+  process.on('SIGTERM', () => shutdown('SIGTERM'));
+  process.on('SIGINT', () => shutdown('SIGINT'));
+  process.on('SIGHUP', () => shutdown('SIGHUP'));
 }
 
 // Backward compat: used by `gbrain call` command (trusted local path).