[omx] warning: failed to write notify fallback watcher pid f

Error message

[omx] warning: failed to write notify fallback watcher pid file

What it means

After launching the watcher, the CLI could not write its PID file to state (writeFile rejected, caught with .catch). The watcher runs but cannot be tracked/stopped later, so a future run may treat it as stale.

Source

Thrown at src/cli/index.ts:7810

  } catch (error: unknown) {
    console.warn("[omx] warning: failed to launch notify fallback watcher", {
      cwd,
      error: error instanceof Error ? error.message : String(error),
    });
    return;
  }

  if (!watcherPid) return;

  await writeFile(
    pidPath,
    JSON.stringify(
      { pid: watcherPid, started_at: new Date().toISOString() },
      null,
      2,
    ),
  ).catch((error: unknown) => {
    console.warn(
      "[omx] warning: failed to write notify fallback watcher pid file",
      {
        path: pidPath,
        error: error instanceof Error ? error.message : String(error),
      },
    );
  });
}

async function startHookDerivedWatcher(cwd: string): Promise<void> {
  if (process.env.OMX_HOOK_DERIVED_SIGNALS !== "1") return;

  const { mkdir, writeFile, readFile } = await import("fs/promises");
  const pidPath = hookDerivedWatcherPidPath(cwd);
  const pkgRoot = getPackageRoot();
  const watcherScript = resolveHookDerivedWatcherScript(pkgRoot);
  if (!existsSync(watcherScript)) return;

View on GitHub (pinned to 3ad79a8a6f)

Solutions

Free disk space and retry
Ensure only one omx instance performs setup per project at a time
Fix ownership of .omx/state

Example fix

// before
df -h .   # 100% full

# after
df -h .   # free space available; rerun omx

Defensive patterns

Strategy: validation

Validate before calling

import { accessSync, constants } from 'node:fs';
function dirWritable(d: string): boolean {
  try { accessSync(d, constants.W_OK); return true; } catch { return false; }
}

Prevention

Check disk space and state-dir writability before launching watchers
Serialize watcher setup across concurrent omx runs

When it happens

Trigger: writeFile(pidPath, JSON.stringify({pid,...})) rejects — disk full, permission lost between mkdir and write, or the state directory was removed concurrently.

Common situations: Disk-full CI runners; concurrent omx invocations racing to set up/tear down state; directory permissions changed mid-run.

Related errors

AI-assisted analysis of Yeachan-Heo/oh-my-codex@3ad79a8a6f (2026-08-27). Data as JSON: /api/errors/185766621869f829. Report an issue: GitHub.