Codex cannot get results from delayed handlers registerd with registerCliHandler

Developers: Plugin & API
1

Codex cannot read registerCliHandler results when the handler returns after a short delay

I found what looks like a bug or incompatibility between Codex and Obsidian CLI plugin commands.

I ran into this while building a plugin that extends the Obsidian CLI for automation / agent use.

Versions and environments

  • NixOS/install via home-manager

  • Obsidian Installer 1.12.7

  • Obsidian: 1.12.7

  • Codex: 118.0

Summary

If a community plugin registers a CLI command with plugin.registerCliHandler(...), Codex can read the command output when the handler returns quickly, but Codex cannot read the result when the handler returns after a short delay.

I put a minimal reproduction plugin here:

https://github.com/daichi-629/long-run-command-bug-repro-plugin

Minimal plugin reproduction

import { Plugin, type CliHandler } from "obsidian";

export default class ReproPlugin extends Plugin {
  async onload(): Promise<void> {
    const handler: CliHandler = async () => {
      const start = Date.now();
      await new Promise((resolve) => window.setTimeout(resolve, 20));
      return JSON.stringify(
        { durationMs: Date.now() - start },
        null,
        2
      );
    };

    this.registerCliHandler("repro-sleep", "repro", null, handler);
  }
}

Expected

obsidian repro-sleep

should return JSON like:

{
  "durationMs": 20
}

Comparison

Works:

  • Running the same command directly from a shell returns the expected JSON.
  • Telling Codex to invoke the command in TTY mode also returns the expected JSON.
  • In Codex normal mode, a delay around 15ms still seems to work.

Fails:

  • In Codex normal mode, a delay around 20ms starts producing empty stdout.
  • Exit code is still 0.

So this looks like a timing-dependent failure around the Codex execution path for Obsidian CLI plugin handlers.

What I checked

  • I had Codex repeatedly run the command while varying the delay.
  • This does not seem to be a general delayed stdout problem.
  • The issue seems to show up specifically when a registerCliHandler(...) command returns only after a slightly longer delay.

My main question is:

  • is this likely a Codex-side stdout capture issue?
  • or is this likely an Obsidian CLI / registerCliHandler(...) issue?
2

As you don’t show your Codex prompt, hard to say. Maybe you have to tell it to launch the command and wait until it outputs?