[Bug] MultiAgentV2 developer instruction incorrectly forbids model/effort overrides with fork_turns="all"

What version of Codex CLI is running?

0.153.4

What subscription do you have?

Pro

Which model were you using?

No response

What platform is your computer?

No response

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

No response

Codex doctor report

What issue are you seeing?

MultiAgentV2 injects an outdated developer instruction saying that full-history forks (fork_turns: "all") cannot override model or reasoning_effort.

However, merged PR #33631 changed the implementation to support model/reasoning overrides for full-history forks while preserving the parent context. The developer instruction was not updated accordingly.

What steps can reproduce the bug?

Using Codex CLI 0.153.4 with MultiAgentV2, ask Codex to spawn a full-history agent with a different model:

{"fork_turns":"all","model":""}

Codex may refuse because the injected developer instruction says this is unsupported, even though the current implementation supports it.

What is the expected behavior?

No response

Additional information

No response

Start by locating the MultiAgentV2 developer instruction that describes fork_turns="all", then compare it with the implementation change in PR #33631. Update the instruction so full-history forks can override model and reasoning_effort, and verify that the reproduced CLI request is no longer refused.