Summary

runExtractFacts in src/core/cycle/extract-facts.ts treats opts.slugs = [] the same as opts.slugs being omitted because the guard checks falsiness on the array, not its presence. A sync no-op therefore turns into a full-brain facts walk via engine.getAllSlugs(). On multi-thousand-page brains this exceeds the autopilot-cycle timeout (~600s) and the job dead-letters with timeout exceeded.

Repro

1. Brain with several thousand pages (reproduced on a 6,492-page Supabase brain; smaller brains should reproduce as long as the full walk exceeds the autopilot-cycle timeout).
2. Run a sync with no changes — autopilot subsequently dispatches an autopilot-cycle job whose sync phase ends with slugs: [] (incremental no-op).
3. The cycle reaches [cycle.extract_facts] start and runs for the full timeout window before dead-lettering.

$ gbrain jobs list --status active
ID     Name             Status  ...
1037   autopilot-cycle  active  ...   ← stays active until ~600s timeout

$ tail -f ~/.gbrain/autopilot.err
[cycle.extract_facts] start
... (no further output until timeout) ...
Autopilot stopping (cycle-failure-cap).

Root cause

src/core/cycle/extract-facts.ts (current 3933eb6/v0.35.1.0):

let slugs: string[];
if (opts.slugs && opts.slugs.length > 0) {
  slugs = opts.slugs;
} else {
  // Full walk: every page in the brain.
  const allSlugs = await engine.getAllSlugs();
  slugs = Array.from(allSlugs);
}

opts.slugs && opts.slugs.length > 0 is falsy for both `undefined` (intended full-walk) AND [] (incremental no-op from sync). Callers passing the empty array unintentionally trigger the full walk.

Suggested fix

Make presence — not length — distinguish the modes:

let slugs: string[];
if (opts.slugs !== undefined) {
  // Empty array is a real incremental no-op from sync. Do not fall back
  // to a full-brain walk or autopilot no-change cycles time out.
  slugs = opts.slugs;
} else {
  const allSlugs = await engine.getAllSlugs();
  slugs = Array.from(allSlugs);
}

Regression test

// test/extract-facts-phase.test.ts
test('runExtractFacts with empty slugs array scans 0 pages (incremental no-op)', async () => {
  const result = await runExtractFacts(engine, { slugs: [] });
  expect(result.pagesScanned).toBe(0);
});

Verification post-fix

On the same 6,492-page brain, post-patch runExtractFacts({ slugs: [] }) completes in ~0.4s; autopilot job that previously dead-lettered at ~600s now completes inside one cycle.

Workaround

Carry a local patch with the presence check above. Has been running on my install since 2026-05-13 (v0.33.1.0) with no regressions across the v0.34.x and v0.35.x wave.

Environment

• gbrain v0.35.1.0 (3933eb6)
• Bun 1.3.13
• Supabase Postgres (ap-south-1 session-mode pooler, 5432)
• macOS Sequoia 15.6