Add existing worktree import flow

[joshdoe]

Summary

• add a UI flow for importing existing Git worktrees into the app
• add Electron IPC support for discovering and importing worktree metadata
• connect imported worktrees into task persistence and sidebar/task panel flows

[johannesjo]

Thank you very much for this and sorry for the late reply. Somehow I wasn't receiving notifications for PRs opened here....

Code Review

Overall: Well-structured PR. The implementation follows codebase patterns closely, the externalWorktree flag is properly threaded through close/merge/persistence paths, and the backend worktree parsing is solid. Security is handled correctly (path validation, array-form exec, preload allowlist).

Important Issues

1. Misleading close message in TilingLayout.tsx:117-119

The force-close confirmation says "The worktree and branch will be deleted" for external worktrees, which is incorrect — they're intentionally kept. This file wasn't updated in the PR:

// Current (incorrect for external worktrees):
const msg = task.directMode
  ? 'Close this task? Running agents and shells will be stopped.'
  : 'Close this task? The worktree and branch will be deleted.';

// Suggested:
const msg = task.directMode || task.externalWorktree
  ? 'Close this task? Running agents and shells will be stopped.'
  : 'Close this task? The worktree and branch will be deleted.';

2. No duplicate import guard in createImportedTask (src/store/tasks.ts)

The UI filters already-tracked paths via trackedWorktreePaths, but createImportedTask itself has no guard against importing the same worktree path twice. A rapid double-click or programmatic call could create duplicates. Compare with createDirectTask which has the hasDirectModeTask() guard at line 144. Suggestion:

const allTaskIds = [...store.taskOrder, ...store.collapsedTaskOrder];
if (allTaskIds.some((id) => store.tasks[id]?.worktreePath === worktree.path)) {
  throw new Error('Worktree is already tracked as a task');
}

Minor Notes

• Partial import failure (ImportWorktreesDialog.tsx): Sequential import means if one fails mid-batch, earlier ones are already created. The dialog shows the error but doesn't indicate how many succeeded (e.g. "2 of 5 imported"). Works correctly on reopen though (filters out already-tracked).
• File length: ImportWorktreesDialog.tsx is 364 lines vs. the 300-line guideline. The StatusBadge helper at the bottom could be extracted.

What's done well

• externalWorktree flag correctly propagated through all persistence layers (types, save, restore, autosave)
• Close task properly skips git cleanup for external worktrees
• Merge dialog defaults initialCleanup: false for imports
• Backend: validatePath on IPC, array-form exec, safeRealpath fallback
• Auto-import prompt on project add is a nice UX touch