Windows: codex exec intermittently remains alive for ~60 seconds after turn.completed

[HadornMarcel]

Windows: codex exec --json intermittently waits ~60 seconds after turn.completed

Summary

On Windows 11, codex exec --json can remain running for roughly one minute after it has already produced a valid response and emitted turn.completed.

The model response itself arrives in a few seconds. The additional delay occurs before the local Codex process exits with exit code 0.

Environment

• OS: Windows 11
• Shell: Windows PowerShell
• Codex CLI: 0.142.5
• Mode: codex exec --json
• Workspace: empty temporary directory
• User configuration and project rules: ignored
• Git repository check: skipped
• Web search: disabled
• Analytics: disabled in one reproduced slow test
• Model: gpt-5.4-mini
• Reasoning effort: low

Reproduction command

$empty=Join-Path $env:TEMP 'codex-clean-latency-test'; New-Item -ItemType Directory -Force $empty | Out-Null; $started=Get-Date; & codex exec --json --ephemeral --ignore-user-config --ignore-rules --skip-git-repo-check --cd $empty -c 'web_search="disabled"' -c 'model_reasoning_effort="low"' -c 'analytics.enabled=false' -m gpt-5.4-mini 'Reply with exactly: OK.' 2>&1 | ForEach-Object { "{0:HH:mm:ss.fff} {1}" -f (Get-Date), $_ }; $exit=$LASTEXITCODE; $ended=Get-Date; $elapsed=($ended-$started).TotalSeconds; "{0:HH:mm:ss.fff} PROCESS EXITED | exit_code={1} | total_elapsed={2:N3}s" -f $ended,$exit,$elapsed

Expected behavior

codex.exe should exit promptly after emitting turn.completed.

Slow runs observed

Run 1 — analytics disabled

19:05:21.358 {"type":"thread.started", ...}
19:05:21.377 {"type":"turn.started"}
19:05:28.175 {"type":"item.completed","item":{"type":"agent_message","text":"OK"}}
19:05:28.178 {"type":"turn.completed", ...}
19:06:25.520 PROCESS EXITED | exit_code=0 | total_elapsed=64.825s

Post-completion delay: approximately 57.3 seconds.

Run 2 — same relevant command options, without the analytics override

18:53:40.104 {"type":"thread.started", ...}
18:53:40.133 {"type":"turn.started"}
18:53:43.379 {"type":"item.completed","item":{"type":"agent_message","text":"OK"}}
18:53:43.385 {"type":"turn.completed", ...}
18:54:49.984 PROCESS EXITED | exit_code=0 | total_elapsed=70.576s

Post-completion delay: approximately 66.6 seconds.

Impact

A Python application using subprocess.run() blocks until Codex exits even though the model response is already available. This makes Streamlit and similar integrations intermittently 1+ minute slower than necessary.

Possible area to investigate

The pattern suggests an intermittent Windows shutdown or cleanup problem after a completed Codex turn, such as process cleanup, event-loop shutdown, or connection teardown timing out.