affaan-m/ECC · error

Cannot adapt Antigravity agent

Error message

Cannot adapt Antigravity agent ${label}: missing YAML frontmatter

What it means

splitFrontmatter adapts Claude agent files for the Antigravity target and requires the source to start with a YAML frontmatter block delimited by '---' lines (matching /^---\r?\n[\s\S]*?\r?\n---\r?\n/). If the regex does not match, the file cannot be transformed, so it throws with the file label. This keeps malformed agent sources from silently installing without metadata.

Solutions

1. Add a valid YAML frontmatter block ('---' on its own line, then YAML, then closing '---') at the top of the agent file.
2. Remove any BOM or leading blank lines so the file starts exactly with '---'.
3. Verify delimiters have no trailing spaces: lines must be exactly '---'.
4. If the file is not an agent, move it out of the path the Antigravity transform processes.

Example fix

<!-- before: agent.md had no frontmatter -->
<!-- after -->
---
name: my-agent
description: Does a thing
---

Agent body markdown...

const hasFrontmatter = (src) => /^---\r?\n[\s\S]*?\r?\n---\r?\n/.test(String(src || ''));
if (!hasFrontmatter(source)) throw new Error(`${label}: missing YAML frontmatter`);

try {
  const { frontmatter, body } = splitFrontmatter(source, label);
} catch (e) {
  if (e.message.includes('missing YAML frontmatter')) {
    console.error(`${label}: add a '---' delimited frontmatter block at the top of the file.`);
  }
  throw e;
}

When it happens

Trigger: Adapting an agent markdown file that lacks a leading '---' frontmatter block entirely; files starting with a BOM or whitespace before the first '---'; Windows files where only the opening delimiter exists; passing an empty/undefined source string (String(source || '')).

Common situations: A newly added agent written without frontmatter; a doc-style markdown accidentally placed in the agents directory; an editor or generator stripping frontmatter; hand-edited agent files with '--- ' (trailing space) delimiters that break the strict regex.

Related errors

• Cannot adapt Antigravity agent
• WARN
• Another ECC process is updating Claude settings
• At least one guided harness must be selected
• ${blockingIssues.map(issue => issue.message).join('; ')}

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/b1d408c991f4a99e. Report an issue: GitHub.

Appendix: source

Thrown at scripts/lib/install/antigravity-agent.js:23

  Write: 'write_to_file',
  Edit: 'replace_file_content',
  Grep: 'grep_search',
  Glob: 'find_by_name',
  Bash: 'run_command',
  WebSearch: 'search_web',
  WebFetch: 'read_url_content',
});

const MODEL_NAMES = Object.freeze({
  haiku: 'flash',
  sonnet: 'pro',
  opus: 'pro',
});

function splitFrontmatter(source, label) {
  const match = String(source || '').match(/^---\r?\n([\s\S]*?)\r?\n---\r?\n/);
  if (!match) {
    throw new Error(`Cannot adapt Antigravity agent ${label}: missing YAML frontmatter`);
  }

  // Keep YAML loading behind the transform boundary. Public help commands load
  // the installer graph without executing a transform, including in hermetic
  // packed-artifact checks where runtime dependencies are intentionally absent.
  const frontmatter = require('js-yaml').load(match[1]);
  if (!frontmatter || typeof frontmatter !== 'object' || Array.isArray(frontmatter)) {
    throw new Error(`Cannot adapt Antigravity agent ${label}: frontmatter must be an object`);
  }

  return {
    frontmatter,
    body: source.slice(match[0].length),
  };
}

function normalizeToolNames(value) {
  const names = Array.isArray(value) ? value : String(value || '').split(',');

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