Active steers ignore model/reasoning changes

[brsbl]

Summary

Changing the model or reasoning level while a turn is active does not affect an immediate steer. The composer displays the new selection, but the steer silently uses the active turn's existing execution tuple.

Versions and environment

• Source desktop build at 74f45e31b72f2f3f141325d54788d56bb1878100; the affected files are byte-identical to origin/main at 88abdac575d21e80bc13c528838e7d2060904c11
• Fresh isolated dev data directory and disposable Codex thread
• macOS 26.5.2 (25F84)
• Codex CLI 0.147.0
• Steer running threads on Enter left disabled; the steer was sent with Command+Enter

Steps to reproduce

1. Start a Codex thread using 5.6-Terra with High reasoning.
2. Submit: Run sleep 30 in the terminal, then reply only with done.
3. While the command is still running, change the composer picker to 5.6-Luna with Low reasoning.
4. Enter Steer: stop waiting and reply only with steered. and press Command+Enter.

This reproduced five times consecutively with the same UI state and stored execution fields.

Expected vs actual

Expected: either the selected 5.6-Luna · Low tuple applies to the message, or execution controls remain read-only while steering with an explanation that the active tuple cannot change.

Actual UI immediately before and after steering:

Codex: 5.6-Luna · Low reasoning

Actual stored steer request, trimmed verbatim:

{
  "target": {
    "kind": "steer"
  },
  "execution": {
    "model": "gpt-5.6-terra",
    "permissionMode": "full",
    "reasoningLevel": "high",
    "serviceTier": "default",
    "source": "client/turn/requested"
  }
}

The selected tuple is therefore not only a display preference: the steer is stored and executed with the previous tuple.

Evidence

• Command+Enter invokes the modifier-submit handler while primary Enter remains the normal submit gesture.
• The normal follow-up request includes the selected execution fields, but the steer request omits them.
• The active-steer shortcut builds that execution-less request, and the composer submits it directly.

What you ruled out

• Not only stale picker state: the stored steer request also contains the previous gpt-5.6-terra / high tuple.
• Not fixed by current main: the relevant request-building and submission files are unchanged at 88abdac575d21e80bc13c528838e7d2060904c11.
• No matching open or closed issue found for steer model reasoning ignored, execution picker steer, model resets after steer, or reasoning steer active thread.

Checks

• Reproduced five times consecutively on the source desktop app with identical results.
• Verified the picker state and stored execution tuple for all five reproductions.
• Searched open and closed issues for the same problem.

AGENT GENERATED: by GPT-5