TUI: add /rename command to set or change a session title #19412

Feature Request

Summary

Add a /rename slash command (or equivalent) to the TUI that allows setting or changing the title of the current session interactively.

Motivation

Currently, session titles can only be set at creation time via the --title flag on opencode run. There is no way to title or rename a session from within the TUI. When listing sessions (/sessions), a title field is shown, but there is no way to populate or change it interactively.

Proposed solution

Add a /rename slash command (with a corresponding keybind, e.g. ctrl+x R) that prompts the user for a new title and updates the current session's title.

Example usage

/rename Fix auth bug in submission portal

Alternatives considered

• Using opencode run --title at session start — works, but requires knowing the title upfront and only applies to non-interactive use
• No workaround exists for renaming a session after it has started in the TUI