affaan-m/ECC · error · Error

Memory frontmatter field in ${sourcePath} must use a JSON va

Error message

Memory frontmatter field in ${sourcePath} must use a JSON value.

What it means

Thrown by parseFrontmatterLine() when JSON.parse() fails on the value portion of a frontmatter line. The parser requires every value to be a JSON literal — strings must be double-quoted, arrays use JSON syntax, numbers/booleans/null are bare. Unquoted strings, single-quoted strings, YAML-style lists, and trailing commas all fail.

Source

Thrown at scripts/lib/memory-vault-format.js:239

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.`);
  }
  if (Buffer.byteLength(source, 'utf8') > MAX_DOCUMENT_BYTES) {
    throw new Error(`Memory document ${sourcePath} is too large.`);
  }

  const frontmatterStart = openingMarker[0].length;
  const remainder = source.slice(frontmatterStart);
  const closingMarker = /\r?\n---(?=\r?\n|$)/.exec(remainder);
  if (!closingMarker) {

View on GitHub (pinned to 01e15490f0)

Solutions

Wrap every string value in double quotes: title: "My Note".
Use JSON arrays: tags: ["a","b","c"].
Quote timestamps so the colon inside does not confuse splitting: created_at: "2024-08-12T00:00:00.000Z".
Regenerate the file via serializeMemoryDocument(); it always emits valid JSON values.

Example fix

// before
---
title: My Handoff
tags: [redis, cache]
created_at: 2024-08-12T00:00:00.000Z
---

// after
---
title: "My Handoff"
tags: ["redis","cache"]
created_at: "2024-08-12T00:00:00.000Z"
---

Defensive patterns

Strategy: validation

Validate before calling

function isJsonLiteral(valueText) {
  try { JSON.parse(valueText); return true; } catch { return false; }
}
const valuePart = line.slice(line.indexOf(':') + 1).trim();
if (!isJsonLiteral(valuePart)) {
  throw new Error(`frontmatter value is not JSON: ${valueText}`);
}

Prevention

Double-quote every string value, including timestamps (they contain colons).
Use JSON array syntax for tags/links/target_harnesses: ["a","b"].
Do not use YAML block lists or single-quoted strings — only JSON.

When it happens

Trigger: A line 'title: My Note' (unquoted string), 'title: \'My Note\'' (single quotes), 'tags: [a, b, c]' (unquoted array elements), 'tags:\n - a' (YAML block style), or 'created_at: 2024-08-12T...' (unquoted timestamp). All of these are valid YAML but invalid JSON.

Common situations: User familiar with YAML wrote frontmatter by hand. AI agent copied from a YAML-frontmatter doc (jekyll/hugo style). Editor auto-formatted to YAML conventions. Field value contains a colon, breaking naive colon-splitting unless quoted.

Related errors

AI-assisted analysis of affaan-m/ECC@01e15490f0 (2026-08-13). Data as JSON: /api/errors/4e8b00b1be059bfe. Report an issue: GitHub.