The CodexAppServerClient communicates with the codex-acp subprocess over stdio. If the subprocess encounters an initialization failure (for instance, an interactive prompt emitted to stdout, or a deprecated config file throwing an error string), the subprocess writes plaintext text to stdout and then abruptly exits. Currently, CodexAppServerClient.handleLine attempts to JSON.parse() this stdout text, fails, and catches the parsing error. When the child process exits immediately after (closing its pipe), OpenClaw subsequently attempts to write the JSON-RPC initialize payload to the deceased subprocess's stdin. Because no error listener is attached to the stdin stream, Node.js throws an unhandled write EPIPE exception, which cascades to immediately terminate the entire OpenClaw gateway daemon. Attach an error event handler to child.stdin to swallow expected pipe lifecycle tear-down errors: child.stdin.on('error', (err) => { log.debug('codex app-server stdin error', { err });

TL;DR

Attach an error event handler to child.stdin to prevent the OpenClaw gateway daemon from terminating due to unhandled write EPIPE exceptions.

Guidance

• Verify that the child.stdin stream is properly set up and accessible before attempting to attach an event handler.
• Implement the proposed fix by attaching an error event handler to child.stdin as shown in the provided code snippet.
• Ensure that the error handler correctly swallows expected EPIPE errors while logging other unexpected errors for debugging purposes.
• Test the fix by simulating a subprocess initialization failure and verifying that the OpenClaw gateway daemon remains operational.

Example

The provided code snippet demonstrates how to attach an error event handler to child.stdin:

if (child.stdin) {
    child.stdin.on('error', (err) => {
        if (err.code !== 'EPIPE') {
            log.debug('codex app-server stdin error', { err });
        }
    });
}

This code checks if child.stdin is truthy before attaching the event handler, ensuring that the handler is only added when the stream is available.

Notes

This fix assumes that the child.stdin stream is properly set up and that the error event handler is correctly implemented. If issues persist, further debugging may be necessary to identify the root cause.

Recommendation

Apply the proposed workaround by attaching an error event handler to child.stdin, as this should prevent the OpenClaw gateway daemon from terminating due to unhandled write EPIPE exceptions.