CLI /fast docs mention on/off/status, but TUI behaves like a toggle

What version of Codex CLI is running?

codex-cli 0.139.0

What subscription do you have?

Pro

Which model were you using?

gpt-5.5

What platform is your computer?

Darwin 25.5.0 arm64 arm

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

Codex CLI TUI.

Codex doctor report

not included; this looks like a slash-command parsing / documentation mismatch.

What issue are you seeing?

The public Codex docs say the CLI supports:

• /fast on
• /fast off
• /fast status

Docs:

• https://developers.openai.com/codex/speed
• https://developers.openai.com/codex/cli/slash-commands

In codex-cli 0.139.0, /fast appears to behave as a local service-tier toggle, but the documented on, off, and status arguments do not appear to be parsed as explicit subcommands.

Manual check on codex-cli 0.139.0:

1. Started the TUI with gpt-5.5 medium.
2. Typed /fast on.
3. The input rendered with /fast highlighted and on as trailing text.
4. Submitted it.
5. The TUI entered Working, token/context usage increased, and the assistant replied to the message.
6. The status line still showed gpt-5.5 medium, not gpt-5.5 medium fast.

So /fast on is not behaving like a local "turn Fast mode on" command in the same way that bare /fast behaves as a local toggle.

What steps can reproduce the bug?

1. Run codex with codex-cli 0.139.0.
2. In the TUI, type /fast on.
3. Submit it.
4. Observe that it is handled like a user message rather than a local slash command.
5. Compare with the docs, which describe explicit /fast on, /fast off, and /fast status forms.

What is the expected behavior?

Either:

• /fast on, /fast off, and /fast status should be handled as documented; or
• the docs should say that /fast is a bare toggle and remove the on/off/status examples.

Additional information

I could not find an existing issue or discussion specifically tracking this CLI documentation/behavior mismatch. Similar reports such as #25849 are about the Codex App, not this CLI TUI docs mismatch.