Method watchCurrentBranchRef

src/utils/git/gitFilesystem.ts:391–427

* Watch the loose ref file for the current branch. * Called on startup and whenever HEAD changes (branch switch).

()

   * Called on startup and whenever HEAD changes (branch switch).
   */
  private async watchCurrentBranchRef(): Promise<void> {
    if (!this.gitDir) {
      return
    }

    const head = await readGitHead(this.gitDir)
    // Branch refs live in commonDir for worktrees (gitDir for regular repos)
    const refsDir = this.commonDir ?? this.gitDir
    const refPath =
      head?.type === 'branch' ? join(refsDir, 'refs', 'heads', head.name) : null

    // Already watching this ref (or already not watching anything)
    if (refPath === this.branchRefPath) {
      return
    }

    // Stop watching old branch ref. Runs for branch→branch AND
    // branch→detached (checkout --detach, rebase, bisect).
    if (this.branchRefPath) {
      unwatchFile(this.branchRefPath)
      this.watchedPaths = this.watchedPaths.filter(
        p => p !== this.branchRefPath,
      )
    }

    this.branchRefPath = refPath

    if (!refPath) {
      return
    }

    // The ref file may not exist yet (new branch before first commit).
    // watchFile works on nonexistent files — it fires when the file appears.
    this.watchPath(refPath, () => {
      this.invalidate()
    })
  }

  private async onHeadChanged(): Promise<void> {
    // HEAD changed — could be a branch switch or detach.