Function readWorktreeHeadSha

src/utils/git/gitFilesystem.ts:619–640

(
  worktreePath: string,
)

 * malformed. Caller can treat null as "not a valid worktree".
 */
export async function readWorktreeHeadSha(
  worktreePath: string,
): Promise<string | null> {
  let gitDir: string
  try {
    const ptr = (await readFile(join(worktreePath, '.git'), 'utf-8')).trim()
    if (!ptr.startsWith('gitdir:')) {
      return null
    }
    gitDir = resolve(worktreePath, ptr.slice('gitdir:'.length).trim())
  } catch {
    return null
  }
  const head = await readGitHead(gitDir)
  if (!head) {
    return null
  }
  if (head.type === 'branch') {
    return resolveRef(gitDir, `refs/heads/${head.name}`)
  }
  return head.sha
}

/**
 * Read the remote origin URL for an arbitrary directory via .git/config.