Auto-generate and apply a concise thread name after the first prompt

What variant of Codex are you using?

Codex with the existing thread rename capability (/rename / RENAME flow).

What feature would you like to see?

Codex now has a way to manually rename the current thread, but I would like the initial naming flow to be automatic:

1. I start a new thread and enter the first real prompt.
2. Codex derives a short, human-readable thread name from that prompt.
3. Codex automatically applies that name to the current thread by reusing the existing rename path.

For example, if the first prompt is:

Investigate why the app-server schema generation test fails after adding the new config endpoint.

Codex could name the thread something like:

App-server schema test failure

Expected behavior

• After the first user prompt, Codex generates a concise title for the current thread.
• The generated title is applied automatically through the same persistence path used by manual rename.
• The title is short enough to scan in thread history/sidebar/resume lists.
• Codex should not overwrite a title that the user has already manually set.
• If the prompt is too vague, Codex can either keep the current default title or wait until there is enough context.

Why this matters

Manual rename is useful, but it adds friction to every new thread. In practice, thread history becomes hard to scan when titles are long, generic, or just copied from the first prompt. Since Codex already has rename plumbing, automatic first-prompt naming would make the default experience much better without requiring the user to remember to run RENAME manually.

Related issues

This is related to, but slightly different from:

• openai/codex#15444: assistant-invokable rename when the user explicitly asks for it
• openai/codex#14482: setting an initial name manually with codex --name
• openai/codex#24060: auto-updating the title later as the conversation changes

This request is specifically about automatically naming a fresh thread shortly after the first prompt, using the existing rename mechanism.