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

[SawyerHood]

Reproduction & root-cause report: https://get-bb.github.io/reports/issues/1860.html

• Verdict: REPRODUCED · root-cause confidence: high
• Root cause (short): apps/app threadDetailPromptSubmission.ts buildSteerFollowUpRequest/buildFollowUpShortcutRequest (and EmbeddedThreadChat's steer) post {input, mode:"steer-if-active"} without the composer's model/reasoningLevel/permissionMode/serviceTier, so the server's buildExecutionOptions falls back to the active turn's last execution tuple and stores/dispatches the steer with it.
• Proposed fix: Add an execution: FollowUpExecutionSelection argument to buildSteerFollowUpRequest/buildFollowUpShortcutRequest in apps/app/src/views/thread-detail/threadDetailPromptSubmission.ts and spread buildSharedThreadExecutionRequestFields(execution) into the steer-if-active request; pass followUpExecutionSelection from handleModifierSubmit in ThreadDetailPromptArea.tsx; spread executionRequestFields into the steer mutation in EmbeddedThreadChat.tsx handleModifierSubmit. No server/daemon/wire change needed (SendMessageRequest already accepts these fields; queued "Send now" and `bb thread tell --mode …
• Caveats: Reproduced on Linux web dev app (headless Chromium, Playwright Meta+Enter) rather than the macOS desktop build; code path is identical. The dev-browser sandbox could not read request.postData(), so exact HTTP bodies were captured via a window.fetch hook inside the page (run 3). Codex provider semantics mean that even after the fix a mid-turn steer will not actually switch the model for Codex (only…

The report has copy-paste repro steps, screenshots where the bug is visual, code permalinks at the base commit, and repro artifacts. It was independently re-run by a second agent (see its Verification section).

AGENT GENERATED: by Claude Opus 5