[TUI 0.145.0] Esc-Esc Edit/Resume changes gpt-5.6-sol Ultra to xhigh

Start with the Rust TUI's Esc-Esc Edit/Resume flow and the prompt-edit branch creation or attachment path described in the reproduction. Trace how the active conversation's reasoning effort is carried into the branch, then verify that selecting Ultra remains Ultra after Esc-Esc and Enter.

What version of Codex CLI is running?

codex-cli 0.145.0

What subscription do you have?

ChatGPT Pro 5x

Which model were you using?

gpt-5.6-sol

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

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

Windows Command Prompt

Codex doctor report

Not collected. The issue reproduces deterministically in a short, otherwise normal TUI session.

What issue are you seeing?

After selecting gpt-5.6-sol with Ultra reasoning, using the Esc-Esc
Edit/Resume flow silently changes the reasoning effort back to xhigh.

Ultra remains selected during normal conversation turns. The change occurs
immediately after pressing Enter to confirm a previous prompt, before the
restored prompt is submitted again.

What steps can reproduce the bug?

1. Start Codex CLI 0.145.0.

   The TUI initially displays gpt-5.6-sol xhigh.

2. Run /model, select gpt-5.6-sol, and select Ultra.

   The TUI now displays gpt-5.6-sol ultra.

3. Send 1+1=?.

   Codex answers 2, and the TUI still displays gpt-5.6-sol ultra.

4. Send 2+2=?.

   Codex answers 4, and the TUI still displays gpt-5.6-sol ultra.

5. Press Esc twice.

6. The previous prompt, 2+2=?, is highlighted. Press Enter to select it
   for Edit/Resume.

7. Before submitting the restored prompt, observe that the model indicator
   has changed to gpt-5.6-sol xhigh.

What is the expected behavior?

The prompt-edit branch should preserve the active conversation's selected
model and reasoning effort, so it should remain gpt-5.6-sol ultra.

The reasoning effort should not silently fall back to the configured
non-Ultra default when creating a branch from an earlier prompt. If this
reset is intentional, the TUI should clearly disclose it before creating
the branch.

Additional information

• The issue reproduces with one Esc-Esc-Enter gesture; repeated or rapid
  input is not required.
• No reasoning-effort shortcut keys were used.
• Normal conversation turns preserve Ultra.
• The visible change occurs during prompt-edit branch creation or attachment,
  not after a new model response.
• The observed change is confirmed by the TUI model indicator. The next
  request payload was not independently inspected.
• A possible cause is that the prompt-edit fork path uses the configured
  default effort (xhigh) rather than copying the active conversation's
  current effort (Ultra).

Related issues

• #35286 involves the same Esc-Esc-Enter prompt-edit fork path, but reports
  buffered input creating multiple chained forks. This issue reproduces with
  a single gesture and concerns the selected reasoning effort not being
  preserved.
• #35003 involves the same earlier-prompt fork feature in Codex CLI 0.145.0,
  but reports copied record timestamps being rewritten. It does not report
  a model or reasoning-effort change.
• #11013 and #12042 report reasoning effort changing when entering Plan mode.
  This reproduction does not enter Plan mode; it is triggered by confirming
  an Esc-Esc Edit/Resume selection.
• #26930 reports reasoning effort changing in Codex Desktop during
  delegation or continuation. This report is a deterministic Codex CLI TUI
  reproduction involving a prompt-edit branch.