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Codex Issues / #14220

Codex desktop can hang when two long-running tool calls start in parallel in one turn

Open 💬 2 comments Opened Mar 10, 2026 by Nightnzh
💡 Likely answer: A maintainer (github-actions[bot], contributor) responded on this thread — see the highlighted reply below.

Bug Summary

Codex desktop can lose tool outputs and leave a turn permanently unfinished when two long-running tool calls are started in parallel in the same turn.

Environment

  • Codex desktop app
  • WSL enabled
  • Workspace: /mnt/d/codex_app/the_answer_2
  • Shell shown in UI: PowerShell
  • Agent tool execution used bash/WSL
  • Date observed: March 10, 2026
  • Thread ID: 019cd7af-bd08-7f00-be1f-f75845805c4d
  • Stuck turn ID: 019cd81a-8a4e-7832-a644-965a4e2da267

Repro Steps

  1. Open a repo in Codex desktop.
  2. Have the agent run two long-running verification commands in parallel in the same turn:
  • flutter test
  • flutter analyze
  1. Wait for both tool calls to start.

Expected

  • Each tool call returns function_call_output
  • The agent receives both results
  • The turn emits a final answer and task_complete

Actual

  • At 2026-03-10T14:20:57Z, the turn emitted two function_call events for flutter test and flutter analyze
  • No later function_call_output arrived for either call
  • No task_complete event was emitted
  • The session appeared stuck indefinitely

Evidence

  • Last agent message before the hang:
  • 分類功能主流程已通。現在跑完整 flutter test 與 flutter analyze，確認沒有回歸與 lint 問題。
  • Rollout file:
  • C:\Users\love1\.codex\sessions\2026\03\10\rollout-2026-03-10T20-19-04-019cd7af-bd08-7f00-be1f-f75845805c4d.jsonl
  • The rollout stream shows both tool calls being issued, then no tool outputs and no task_complete
  • A later session in the same repo completed successfully, so the repository itself was not in a broken state

Important Non-Causes

  • No lingering flutter or git subprocesses were present when inspected
  • The repository later verified cleanly in a separate session
  • Failed to create shell snapshot for powershell: Shell snapshot not supported yet for PowerShell appeared in logs but does not look like the direct cause
  • This looks more like tool transport / turn orchestration failure than project code failure

Likely Trigger

Parallel long-running tool calls in one turn, especially flutter test plus flutter analyze

View original on GitHub ↗

2 Comments

github-actions[bot] contributor · 5 months ago

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

  • ##13987
  • ##13475

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Nightnzh · 5 months ago

I checked the suggested duplicates.

  • #13475 looks related, but not identical. That issue reports a turn hanging after a successful function_call_output. In my case, the failure happens earlier: the turn emits two long-running tool calls in parallel (flutter test and flutter analyze), then neither tool call ever produces a function_call_output, and the turn never reaches task_complete.
  • #13987 does not look like the same issue. That one is specific to Windows read-only sandbox mode when Codex is running as an MCP server. My repro was in Codex desktop with WSL enabled, not MCP server mode, and not a read-only sandbox repro.

So #13475 seems like the closest related issue, but this report adds a distinct trigger condition: parallel long-running tool calls in the same turn.