# Signal Detector

Opt-in ambient signal capture.

- Repository: https://github.com/garrytan/gbrain (31427 stars)
- Category: AI and agents
- License: MIT
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add garrytan/gbrain --skill signal-detector -g -a claude-code -y`
Codex: `npx skills add garrytan/gbrain --skill signal-detector -g -a codex -y`
Cursor: `npx skills add garrytan/gbrain --skill signal-detector -g -a cursor -y`
Gemini CLI: `npx skills add garrytan/gbrain --skill signal-detector -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add garrytan/gbrain`

## Description

Opt-in ambient signal capture. After explicit enablement, applies on substantive inbound messages to detect original thinking and entity mentions. Use an authorized sub-agent where supported; otherwise detect inline. Aim to never block the main response.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Signal Detector, Ambient Brain Capture

After the user enables automatic capture, apply this lightweight pass to
substantive inbound messages within their chosen scope. It watches for:

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:
- Applies only after explicit automatic-capture opt-in (skips: no recorded
  choice, capture off, chat-only requests, and purely operational messages)
- Spawns as a sub-agent where the harness supports it; otherwise runs the
  detection inline before composing the reply. Never blocking the response
  is the intent, not a runtime contract
- Checks the user's stored capture choice before writing and honors narrower
  per-message instructions; a first-fire announcement is not consent
- 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

The rest: https://github.com/garrytan/gbrain/blob/HEAD/plugin-variants/gbrain-coding/skills/signal-detector/SKILL.md