Function installFromGitSubdir

src/utils/plugins/pluginLoader.ts:718–851

(
  url: string,
  targetPath: string,
  subdirPath: string,
  ref?: string,
  sha?: string,
)

 * the plugin files with no .git directory.
 */
export async function installFromGitSubdir(
  url: string,
  targetPath: string,
  subdirPath: string,
  ref?: string,
  sha?: string,
): Promise<string | undefined> {
  if (!(await checkGitAvailable())) {
    throw new Error(
      'git-subdir plugin source requires git to be installed and on PATH. ' +
        'Install git (version 2.25 or later for sparse-checkout cone mode) and try again.',
    )
  }

  const gitUrl = resolveGitSubdirUrl(url)
  // Clone into a sibling temp dir (same filesystem → rename works, no EXDEV).
  const cloneDir = `${targetPath}.clone`

  const cloneArgs = [
    'clone',
    '--depth',
    '1',
    '--filter=tree:0',
    '--no-checkout',
  ]
  if (ref) {
    cloneArgs.push('--branch', ref)
  }
  cloneArgs.push(gitUrl, cloneDir)

  const cloneResult = await execFileNoThrow(gitExe(), cloneArgs)
  if (cloneResult.code !== 0) {
    throw new Error(
      `Failed to clone repository for git-subdir source: ${cloneResult.stderr}`,
    )
  }

  try {
    const sparseResult = await execFileNoThrowWithCwd(
      gitExe(),
      ['sparse-checkout', 'set', '--cone', '--', subdirPath],
      { cwd: cloneDir },
    )
    if (sparseResult.code !== 0) {
      throw new Error(
        `git sparse-checkout set failed (git >= 2.25 required for cone mode): ${sparseResult.stderr}`,
      )
    }

    // Capture the resolved commit SHA before discarding the clone. The
    // extracted subdir has no .git, so the caller can't rev-parse it later.
    // If the source specified a full 40-char sha we already know it; otherwise
    // read HEAD (which points to ref's tip after --branch, or the remote
    // default branch if no ref was given).
    let resolvedSha: string | undefined

    if (sha) {
      const fetchSha = await execFileNoThrowWithCwd(