Signal Detector

Signal Detector — Ambient Brain Capture

Lightweight sub-agent that fires on every inbound message to capture TWO things with EQUAL priority:

1. Original thinking — the user's ideas, observations, theses, frameworks
2. Entity mentions — people, companies, media references

Original thinking is AT LEAST as valuable as entity extraction. Ideas are the intellectual capital. Entities are bookkeeping. Both compound over time.

Contract

This skill guarantees:

• Fires on every message (no exceptions unless purely operational)
• Runs in parallel (spawned, never blocks main response)
• Captures ideas with the user's EXACT phrasing (no paraphrasing)
• Detects entity mentions and creates/enriches brain pages
• Logs a one-line summary of what was captured
• Back-links all entity mentions (Iron Law)
• Citations on every fact written

Convention: See skills/conventions/quality.md for Iron Law back-linking.

Every time this skill creates or updates a brain page that mentions a person or company:

1. Check if that person/company has a brain page
2. If yes → add a back-link FROM their page TO the page you just created/updated
3. Format: - **YYYY-MM-DD** | Referenced in [page title](path) — brief context
4. An unlinked mention is a broken brain.

Phases

Phase 1: Idea/Observation Detection (PRIMARY)

When the user expresses a novel thought, observation, thesis, or framework:

• If it's the user's original thinking (they generated it) → create/update originals/{slug}
• If it's a world concept they're referencing → create/update concepts/{slug}
• If it's a product or business idea → create/update ideas/{slug}

Capture exact phrasing. The user's language IS the insight. Don't paraphrase.

Cross-linking (MANDATORY): Every original MUST link to related people, companies, meetings, and concepts. An original without cross-links is a dead original.

Phase 2: Entity Detection (SECONDARY)

1. Extract entity mentions (people, companies, media titles)
2. For each entity:
   • gbrain search "name" — does a page exist?
   • If NO page → check notability. If notable, create page with enrichment.
   • If page exists but THIN → trigger enrich
   • If page exists and RICH → no action
3. For new FACTS with specific dates → call gbrain timeline-add <slug> <date> "<summary>"

Auto-link (v0.10.1): When you write/update an originals or ideas page that references a person or company, the auto-link post-hook on put_page automatically creates the link from the new page to that entity. You don't need to call gbrain link manually. Timeline entries still need explicit calls.

Phase 3: Signal Logging

Always log a one-line summary:

• Signals: 0 ideas, 0 entities, 0 facts (skipped: operational)
• Signals: 1 idea (captured → originals/x), 2 entities (enriched → people/y, companies/z)

This makes the ambient capture loop debuggable.

Output Format

No visible output to the user. This skill runs silently in the background. The output is brain pages created/updated and the signal log line.

Anti-Patterns

• Blocking the main response to wait for signal detection to complete
• Paraphrasing the user's original thinking instead of capturing exact phrasing
• Creating pages for non-notable entities (one-off mentions)
• Skipping back-links after creating/updating pages
• Running on purely operational messages ("ok", "thanks", "do it")

Tools Used

• search — check if entity page exists
• query — semantic search for related context
• get_page — load existing entity pages
• put_page — create/update brain pages
• add_link — cross-reference entities
• add_timeline_entry — record events on entity timelines

Source: garrytan/gbrain → skills/signal-detector/SKILL.md