fix(server): preserve fatal log on crash and guard socket.send against close races (#613)

The daemon was dying silently with no log trail. Two compounding causes:

1. uncaughtException/unhandledRejection handlers in index.ts called
   process.exit(1) immediately after logger.fatal, but pino is configured
   with async streams (sync: false console + rotating-file-stream), so the
   fatal entry never flushed. main().catch already worked around this with
   a 200ms setTimeout — extract exitAfterPinoFlush() and apply it to the
   process-level handlers too.

2. socket.send() in the relay transport adapter and ws.send() in
   sendToClient/sendBinaryToClient were unprotected. The ws library throws
   synchronously on send-after-close, and the readyState === 1 check has a
   race window. With an active foreground turn streaming agent_stream
   output, a peer-side disconnect could turn into an uncaughtException —
   which (per #1) then exited without logging.

Wrap the three send sites in try/catch and warn-log on failure; let
onclose/onerror drive cleanup. The readyState fast-path stays as an
optimization.

Refs getpaseo/paseo#612

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/server/src/server/index.ts

@@ -207,19 +207,23 @@ async function main() {
 
   process.on("uncaughtException", (err) => {
     logger.fatal({ err }, "Uncaught exception — daemon crashing");
-    process.exit(1);
+    exitAfterPinoFlush();
   });
 
   process.on("unhandledRejection", (reason) => {
     logger.fatal({ err: reason }, "Unhandled promise rejection — daemon crashing");
-    process.exit(1);
+    exitAfterPinoFlush();
   });
 }
 
+// Give pino async streams a moment to flush the fatal log entry to daemon.log
+// before the process exits. Without this, the last few entries that explain
+// why the daemon crashed can be lost.
+function exitAfterPinoFlush(): void {
+  setTimeout(() => process.exit(1), 200);
+}
+
 main().catch((err) => {
   process.stderr.write(`${err instanceof Error ? (err.stack ?? err.message) : String(err)}\n`);
-  // Give pino streams a moment to flush the fatal log entry to daemon.log
-  // before the process exits. Without this, async file streams may lose the
-  // last few entries that explain why the daemon crashed.
-  setTimeout(() => process.exit(1), 200);
+  exitAfterPinoFlush();
 });

packages/server/src/server/relay-transport.ts

@@ -396,7 +396,7 @@ async function attachEncryptedSocket(
   metadata?: ExternalSocketMetadata,
 ): Promise<void> {
   try {
-    const relayTransport = createRelayTransportAdapter(socket);
+    const relayTransport = createRelayTransportAdapter(socket, logger);
     const emitter = new EventEmitter();
     const channel = await createDaemonChannel(relayTransport, daemonKeyPair, {
       onmessage: (data) => emitter.emit("message", data),
@@ -418,9 +418,18 @@ async function attachEncryptedSocket(
   }
 }
 
-function createRelayTransportAdapter(socket: WebSocket): RelayTransport {
+function createRelayTransportAdapter(socket: WebSocket, logger: pino.Logger): RelayTransport {
   const relayTransport: RelayTransport = {
-    send: (data) => socket.send(data),
+    send: (data) => {
+      try {
+        socket.send(data);
+      } catch (err) {
+        // Socket likely transitioned to closed between checks; let onclose/onerror
+        // drive cleanup. Without this guard the synchronous throw would propagate
+        // up as an uncaughtException and take down the daemon.
+        logger.warn({ err }, "relay_socket_send_failed");
+      }
+    },
     close: (code?: number, reason?: string) => socket.close(code, reason),
     onmessage: null,
     onclose: null,

packages/server/src/server/websocket-server.ts

@@ -738,10 +738,17 @@ export class VoiceAssistantWebSocketServer {
   }
 
   private sendToClient(ws: WebSocketLike, message: WSOutboundMessage): void {
-    // WebSocket.OPEN = 1
-    if (ws.readyState === 1) {
+    // WebSocket.OPEN = 1. The check is a fast path; the socket can still
+    // transition to closed between here and ws.send(), so guard the send too —
+    // a synchronous throw here would propagate as an uncaughtException.
+    if (ws.readyState !== 1) {
+      return;
+    }
+    try {
       ws.send(JSON.stringify(message));
       this.recordOutboundMessage(message, ws);
+    } catch (err) {
+      this.logger.warn({ err }, "ws_send_failed");
     }
   }
 
@@ -749,8 +756,12 @@ export class VoiceAssistantWebSocketServer {
     if (ws.readyState !== 1) {
       return;
     }
-    ws.send(frame);
-    this.recordOutboundBinaryFrame(ws);
+    try {
+      ws.send(frame);
+      this.recordOutboundBinaryFrame(ws);
+    } catch (err) {
+      this.logger.warn({ err }, "ws_send_binary_failed");
+    }
   }
 
   private sendToConnection(connection: SessionConnection, message: WSOutboundMessage): void {