affaan-m/ECC · error · Error

Unknown memory frontmatter field in

Error message

Unknown memory frontmatter field in ${sourcePath}.

What it means

parseFrontmatterLine() looks up the serialized key (the text before the colon) in the FRONTMATTER_KEYS map. Only whitelisted field names are accepted; any other key — even a well-formed `key: value` line — is rejected to keep the document schema strict and catch typos.

Solutions

1. Replace the key with one of the supported frontmatter field names (schema, id, title, targetHarnesses, etc. — the keys FRONTMATTER_KEYS recognizes).
2. Fix casing/typos so the serialized key matches exactly (lookup is exact, not case-insensitive).
3. Move unsupported metadata into the document body below the closing --- instead of frontmatter.
4. Regenerate the document with the library's save path to get canonical keys.

Example fix

// before
---
schema: 1
id: "notes"
titel: "Deploy notes"
---

// after
---
schema: 1
id: "notes"
title: "Deploy notes"
---

const ALLOWED = new Set(['schema', 'id', 'title', 'targetHarnesses']);
for (const line of frontmatterLines) {
  const key = line.slice(0, line.indexOf(':')).trim();
  if (!ALLOWED.has(key)) throw new Error(`Unknown frontmatter key: ${key}`);
}

const isKnownFrontmatterKey = (key) => FRONTMATTER_KEYS.has(key);

try {
  parseMemoryDocument(source, path);
} catch (err) {
  if (err.message.includes('Unknown memory frontmatter field')) {
    console.error('Fix or remove the unrecognized key in %s; supported keys come from FRONTMATTER_KEYS.', path);
  } else throw err;
}

When it happens

Trigger: A frontmatter line with a typo'd or unsupported key such as `titel: "..."`, `tags: [...]`, `author: ...`, or a key whose canonical serialized form differs (wrong casing like `Title:`) so it misses the exact map lookup.

Common situations: Copying frontmatter from another tool (Jekyll/Hugo style keys like `layout:` or `date:`) into a memory document; renaming a key by hand after a schema change; adding custom metadata fields that the format doesn't allow.

Related errors

• Duplicate memory frontmatter field in
• Invalid memory frontmatter line in
• Memory document must start with --- frontmatter.
• Memory frontmatter field in
• -32602

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/d8f44c7f9e265091. Report an issue: GitHub.

Appendix: source

Thrown at scripts/lib/memory-vault-format.js:230

}

function decodeUtf8(buffer, label = 'text') {
  try {
    return FATAL_UTF8_DECODER.decode(buffer);
  } catch {
    throw new Error(`${label} must contain valid UTF-8 text.`);
  }
}

function parseFrontmatterLine(line, sourcePath, seen) {
  const separator = line.indexOf(':');
  if (separator <= 0) {
    throw new Error(`Invalid memory frontmatter line in ${sourcePath}.`);
  }
  const serializedKey = line.slice(0, separator).trim();
  const objectKey = FRONTMATTER_KEYS.get(serializedKey);
  if (!objectKey) {
    throw new Error(`Unknown memory frontmatter field in ${sourcePath}.`);
  }
  if (seen.has(objectKey)) {
    throw new Error(`Duplicate memory frontmatter field in ${sourcePath}.`);
  }
  const rawValue = line.slice(separator + 1).trim();
  try {
    return { objectKey, value: JSON.parse(rawValue) };
  } catch {
    throw new Error(`Memory frontmatter field in ${sourcePath} must use a JSON value.`);
  }
}

function parseMemoryDocument(source, sourcePath = '<memory>') {
  const openingMarker = typeof source === 'string'
    ? /^---\r?\n/.exec(source)
    : null;
  if (!openingMarker) {
    throw new Error(`Memory document ${sourcePath} must start with --- frontmatter.`);

View on GitHub (pinned to 8321021c54)