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