[TUI]: Prompt to attach a branch when graduating a detached worktree

Existing issues

• I searched the existing issues for this interaction.

Current workflow

try worktree <name> intentionally creates a detached worktree. Ctrl-G later moves that worktree to a permanent location, but it does not attach HEAD to a branch.

As a result, the TUI can report a successful graduation while leaving the promoted project detached. Users must know to run this manually before or after graduation:

git switch -c <branch>

The distinction between moving a worktree and attaching its Git HEAD is not visible in the current interaction.

Proposed interaction

When Ctrl-G is used on a detached Git worktree, the TUI should detect the detached state and prompt the user to attach it to a branch.

The prompt should:

1. Explain that the selected worktree has a detached HEAD.
2. Offer an inferred branch name derived from the graduation/worktree name.
3. Allow the branch name to be edited.
4. Run the equivalent of git switch -c <branch> before moving the worktree when confirmed.
5. Allow the user to decline and graduate while detached.

No attachment prompt is needed for a worktree already associated with a branch or for a non-Git directory.

Why this improves the TUI

Branch attachment is part of promoting an ephemeral detached worktree into maintained work. Prompting at the transition point makes the Git state explicit, avoids orphaned commits, and removes a prerequisite that users otherwise have to discover outside try.

Acceptance criteria

• Ctrl-G detects whether a selected Git worktree is detached.
• Detached worktrees receive an attach-branch prompt before the move.
• The prompt includes an editable inferred branch name.
• Confirming performs branch attachment before git worktree move.
• Declining preserves the existing detached graduation behavior.
• Escape cancels without attaching or moving.
• Attachment failure prevents the move and displays an actionable error.
• Already-attached worktrees and normal directories are not prompted.
• Tests cover confirm, edit, decline, cancel, failure, and already-attached states.

try version

try v0.1.0

Shell

zsh

Additional context

The same behavior should be available non-interactively through the proposed try graduate --attach CLI.

Start at the Ctrl-G graduation flow and trace the proposed try graduate --attach entry point, then inspect how Git worktree state and TUI prompts are handled. Done means detached worktrees support editable branch attachment, confirmation, decline, cancellation, and actionable failure handling, with coverage for all listed states while preserving existing behavior.