JuliusBrussee/caveman · error · Error

SKILL.md needs closed YAML frontmatter

Error message

SKILL.md needs closed YAML frontmatter

What it means

Error "SKILL.md needs closed YAML frontmatter" thrown in JuliusBrussee/caveman.

Source

Thrown at packages/cli/src/index.ts:1365

		throw new Error(`source does not exist: ${input}`);
	}
	const stat = lstatSync(resolved);
	const file = stat.isDirectory() ? join(resolved, SKILL_MD) : resolved;
	if (!stat.isDirectory() && basename(resolved) !== SKILL_MD) throw new Error("source file must be named SKILL.md");
	if (!hasFile(file)) throw new Error(`SKILL.md missing under ${resolved}`);
	return { root: stat.isDirectory() ? resolved : dirname(resolved), file };
}

function cavemannifyImportedSkill(bytes: Buffer): { body: string; removedDuplicates: number; removedSeparators: number } {
	if (bytes.length === 0 || bytes.length > 256 * 1024) throw new Error("SKILL.md must be 1..262144 bytes");
	if (bytes.includes(0)) throw new Error("SKILL.md contains NUL bytes");
	const text = bytes.toString("utf8");
	if (!Buffer.from(text, "utf8").equals(bytes)) throw new Error("SKILL.md must be valid UTF-8");
	if (/-----BEGIN [A-Z ]*PRIVATE KEY-----|\b(?:sk|ghp|github_pat|xox[baprs])[-_][A-Za-z0-9_-]{16,}/i.test(text)) {
		throw new Error("SKILL.md contains credential-shaped material");
	}
	const split = splitSkillMarkdown(bytes);
	if (!split) throw new Error("SKILL.md needs closed YAML frontmatter");
	const blocks = split.bodyText.trim().split(/\r?\n(?:[ \t]*\r?\n)+/);
	const seen = new Set<string>();
	const kept: string[] = [];
	let removedDuplicates = 0;
	let removedSeparators = 0;
	for (const block of blocks) {
		const clean = block.trim();
		if (/^(?:---+|\*\*\*+|___+)$/.test(clean)) {
			removedSeparators++;
			continue;
		}
		const identity = clean.replace(/\s+/g, " ");
		if (seen.has(identity)) {
			removedDuplicates++;
			continue;
		}
		seen.add(identity);
		kept.push(clean);

View on GitHub (pinned to 27d5a3981a)

Solutions

1. Add closed YAML frontmatter (--- ... ---) at the top of SKILL.md.

When it happens

Trigger: Thrown at packages/cli/src/index.ts:1365 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/9447ebe5da9df56e. Report an issue: GitHub.