nanocoai/nanoclaw · error · StdinJsonInputError

--stdin-json input is empty

Error message

--stdin-json input is empty

What it means

parseJsonObject requires the --stdin-json stream to contain exactly one JSON object; empty/whitespace-only input throws before parsing.

Source

Thrown at src/cli/stdin-json.ts:65

  const chunks: Buffer[] = [];
  let byteLength = 0;

  for await (const chunk of stream) {
    const buffer = typeof chunk === 'string' ? Buffer.from(chunk, 'utf8') : Buffer.from(chunk);
    byteLength += buffer.byteLength;
    if (byteLength > MAX_STDIN_JSON_BYTES) {
      throw new StdinJsonInputError(`--stdin-json input exceeds ${MAX_STDIN_JSON_BYTES} bytes`);
    }
    chunks.push(buffer);
  }

  return Buffer.concat(chunks, byteLength).toString('utf8');
}

/** Parse the input, requiring exactly one JSON object — not an array, scalar, or null. */
function parseJsonObject(source: string): Record<string, unknown> {
  if (source.trim().length === 0) {
    throw new StdinJsonInputError('--stdin-json input is empty');
  }

  let parsed: unknown;
  try {
    parsed = JSON.parse(source);
  } catch (err) {
    throw new StdinJsonInputError('--stdin-json input is not valid JSON', { cause: err });
  }

  if (parsed === null || typeof parsed !== 'object' || Array.isArray(parsed)) {
    throw new StdinJsonInputError('--stdin-json input must be one JSON object');
  }

  return parsed as Record<string, unknown>;
}

/** Match the key normalization applied by command parsers in crud.ts. */
function canonicalArgKey(key: string): string {

View on GitHub (pinned to 294ef2aee8)

Solutions

1. Pipe the JSON: `ncl ... --stdin-json < args.json` or `cat args.json | ncl ... --stdin-json`
2. If no extra args are needed, drop the --stdin-json flag entirely
3. In scripts, redirect stdin from the intended file, not /dev/null

Example fix

# before
ncl groups create --name x --stdin-json < /dev/null
# after
ncl groups create --name x --stdin-json < args.json

const src = fs.readFileSync(path,'utf8');
if (!src.trim()) throw new Error('empty args file');

function isNonEmptyJson(s: string): boolean { return s.trim().length > 0; }

When it happens

Trigger: Running `ncl ... --stdin-json` with stdin closed, empty, or only whitespace (common in scripts and cron where stdin is /dev/null).

Common situations: Interactive prompt eaten by a prior read, CI job with no stdin, or forgetting to pipe the file.

Related errors

• --stdin-json input exceeds ${MAX_STDIN_JSON_BYTES} bytes
• --stdin-json input is not valid JSON
• --stdin-json input must be one JSON object
• --stdin-json key "__proto__" is not allowed
• --stdin-json key "${key}" is also supplied on argv

AI-assisted analysis of nanocoai/nanoclaw@294ef2aee8 (2026-08-28). Data as JSON: /api/errors/bda652d92894abd5. Report an issue: GitHub.