Function createAskpassSession

src/node/runtime/sshAskpass.ts:83–175

(
  onPrompt: (prompt: string) => Promise<string>
)

 *   must return the response string (e.g. "yes" or "no").
 */
export async function createAskpassSession(
  onPrompt: (prompt: string) => Promise<string>
): Promise<AskpassSession> {
  // Resolve script path before allocating temp resources.
  const scriptPath = await ensureAskpassScript();

  const dir = fs.mkdtempSync(path.join(os.tmpdir(), "mux-askpass-"));
  const processed = new Set<string>();
  let closed = false;

  async function handlePrompt(requestId: string): Promise<void> {
    const promptFile = path.join(dir, `prompt.${requestId}.txt`);
    const responseFile = path.join(dir, `response.${requestId}.txt`);

    try {
      await fs.promises.access(promptFile);
    } catch {
      processed.delete(requestId);
      return;
    }

    if (closed) return;

    try {
      const promptText = await fs.promises.readFile(promptFile, "utf-8");
      const response = await onPrompt(promptText);
      await fs.promises.writeFile(responseFile, response + "\n");
    } catch (err) {
      log.debug("Askpass prompt handling failed:", err);
      // Write rejection to unblock askpass (best-effort)
      try {
        await fs.promises.writeFile(responseFile, "no\n");
      } catch {
        /* askpass may already be gone */
      }
    }
  }

  // Watch for askpass to write prompt files.
  // fs.watch is set up BEFORE SSH is spawned, so we cannot miss events.
  let watcher: fs.FSWatcher;
  try {
    watcher = fs.watch(dir, (_, filename) => {
      if (closed) return;

      void (async () => {
        let candidateFilenames: string[];
        if (typeof filename === "string") {
          candidateFilenames = [filename];
        } else {
          try {
            candidateFilenames = await fs.promises.readdir(dir);
          } catch {
            return;
          }
        }

        for (const candidate of candidateFilenames) {