Why

Interactive codex resume and codex fork expose both a session ID positional and an initial prompt positional. With --last, Clap still assigns the first positional to the session ID, so a command such as codex fork --last "/compact focus on auth" either fails parsing or attempts to look up the prompt as a session ID instead of sending it to the latest session.

This makes it impossible to select the latest session and immediately provide a follow-up prompt, even though codex exec resume --last already supports that workflow.

What Changed

• Reinterpret the first positional as the initial prompt when interactive resume --last or fork --last is used and no explicit second prompt was parsed.
• Preserve the existing resume SESSION_ID PROMPT and fork SESSION_ID PROMPT behavior.
• Add parser-level regression coverage for latest-session and explicit-session prompt forms.

How to Test

1. Start an interactive session, exit it, then run codex resume --last "continue from the latest session".
2. Confirm Codex resumes the latest session and submits the supplied prompt instead of treating it as a session ID.
3. Run codex fork --last "take a different approach".
4. Confirm Codex forks the latest session and submits the supplied prompt.
5. Also verify codex resume SESSION_ID "continue here" and codex fork SESSION_ID "branch here" still target the explicit session and submit the prompt.

Targeted tests:

• just test -p codex-cli (267 passed)