Codex CLI 0.137.0 only spawns sub-agents of the same type

Resolved 💬 3 comments Opened Jun 8, 2026 by tuhdo Closed Jun 10, 2026

💡 Likely answer: A maintainer (github-actions[bot], contributor) responded on this thread — see the highlighted reply below.

What version of Codex CLI is running?

v0.137.0

What subscription do you have?

Pro 20X

Which model were you using?

gpt-5.5

What platform is your computer?

Linux 7.0.10-2-cachyos x86_64

What terminal emulator and version are you using (if applicable)?

Ghostty

Codex doctor report

What issue are you seeing?

Codex 0.137.0 can only spawn subagents of the same type as the default agent. Before, I can tell it to "spawn gpt-5.3-codex-spark-high" while using gpt-5.5-medium. Now, if my default agent is gpt-5.5-medium, the subagents always default to that one.

What steps can reproduce the bug?

Install v0.137.0
Ask codex to spawn a different subagent type, e.g, the main agent is 5.5, the subagent is 5.4

What is the expected behavior?

The subagent must be spawned according to the user's requested model.

Additional information

_No response_

View original on GitHub ↗

3 Comments

github-actions[bot] contributor · 2 months ago

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

#26679
#26363
#26828
#26868
#26948

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futile · 2 months ago

Ran into the same issue, asked Codex CLI to spawn gpt-5.3-codex-spark, but it couldn't do so and instead the subagent also spawned as gpt-5.5-medium (my default & main-thread model at the time):

I’m finding the available subagent launcher now so I can start Spark with that exact scope.

─────────────────────────────────────────────────────────────────────────────────────────────────

• The subagent launcher available here does not expose a model parameter, so I can’t hard-select Spark through the tool API. I’m still launching it with a Spark-scoped bounded patch-worker packet and an explicit model ceiling/request.

• Spawned Mill (gpt-5.5 medium)
  └ Role: bounded patch worker for bead pdo-98p.
  Model request/ceiling: use gpt-5.3-codex-spark if the runner supports model selection. Do not use a model above...

─────────────────────────────────────────────────────────────────────────────────────────────────

• Launched subagent Mill.

  Note: the launcher available in this session does not expose a model selector, so I could not hard-set gpt-5.3-codex-spark. I put the Spark request/ceiling and bounded patch-worker constraints directly in the agent packet.

System info:

❯ codex --version; uname -a
codex-cli 0.137.0
Linux nixos-work 6.18.33 #1-NixOS SMP PREEMPT_DYNAMIC Sat May 23 11:07:21 UTC 2026 x86_64 GNU/Linux

tuhdo · 2 months ago

Fixed in the latest codex 0.139.0