Summary

gbrain sync/ingest crashes in assessContentSanity() when a page's parsed title is undefined:

opts.title.toLowerCase is not a function. (In 'opts.title.toLowerCase()', 'opts.title.toLowerCase' is undefined)

This is the crash from #1556, which the original reporter closed as "premature, filed while validating a local install — will file fresh after confirming against a clean/current install." Confirming here against current master.

Environment

• gbrain HEAD: 041d89b (v0.41.29.0)
• Engine: Postgres + pgvector (Supabase), embedding openai:text-embedding-3-small
• Reproduced: 988 failure events across 247 distinct pages logged to ~/.gbrain/sync-failures.jsonl, all dated right after v0.41.26.0 (v0.41.26.0 fix: dream --source + ingest junk titles + emoji-crash (supersedes #1559, #1561) #1571) landed the junk-title content-sanity check.

Root cause

src/core/content-sanity.ts types the param as title: string (non-optional):

export function assessContentSanity(opts: {
  ...
  title: string;            // <- callers can pass undefined at runtime
  ...
}) {
  ...
  const titleLower = opts.title.toLowerCase();          // throws
  ...
  if (p.pattern.test(opts.title)) ...                   // also unsafe
}

But src/core/import-file.ts (and sources.ts, lint.ts, doctor.ts) call it with title: parsed.title, and parsed.title is undefined whenever a page has no title: frontmatter field. This bites two ways:

1. Title-less pages (e.g. daily/date notes with no title:).
2. History replay: sync replays git history commit-by-commit; a page that has a title: today did not at the historical commits being replayed, so parsed.title is genuinely undefined for those revisions and the whole sync run aborts.

Repro

A markdown file with no title: in frontmatter, then gbrain sync (or import). assessContentSanity throws on the first such page.

Fix

Coerce defensively at the single choke point (covers all four callers) and make the type honest:

title?: string | null;
// ...
const title = String(opts.title ?? '');
const titleLower = title.toLowerCase();
// ...
if (p.pattern.test(title)) ...

All 76 existing content-sanity tests pass; null/undefined/number/empty/string inputs all return a result instead of throwing. PR incoming.