[FEATURE] Run /rename immediately in the background instead of queuing behind the active turn

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When Claude is mid-turn (actively working on a task), typing /rename does not take effect right away. The command is queued and only runs after the current turn finishes.

/rename only sets the session's custom title. It is a local, metadata-only change: it does not call the model and does not need to touch the running task. Queuing it behind the active turn defeats the main reason I rename in the first place: I want to label a session so I can identify it while it is still working, especially when I have several parallel or background sessions open on the same repo. Waiting for a long-running turn to finish before the new name applies makes the feature useless at exactly the moment I need it.

Proposed Solution

Run /rename immediately in the background, even while a turn is in progress: do not queue it behind the active turn and do not interrupt the running task. The new title should apply and persist right away (status line, sidebar, and /resume / session picker).

More generally, purely-local commands that do not depend on the model (e.g. /rename) could be treated as a class that executes on entry rather than queuing.

Alternative Solutions

• Wait for the active turn to finish before the rename applies (current behavior; the friction this request is about).
• Press Esc to interrupt the turn, run /rename, then resume, which is disruptive and risks losing the in-flight turn.

Priority

Low - Nice to have / quality-of-life improvement.