Relationship intelligence for founders — as an open-source Claude skill.
Run /circuit in Claude and it scans your inbox for every active two-way conversation, classifies each by relationship type, and surfaces who you're waiting on, what's due, and what you owe.
Your inbox is your real CRM — it's just unreadable. Circuit reads it for you. It finds the threads where you and a real human are actually going back and forth, throws away the newsletters and no-reply noise, and tells you the only thing that matters: what needs your attention right now.
## Circuit — Active Conversations (Last 30 Days)
*Scanned Jun 7 · 64 sent threads · 22 two-way confirmed*
| # | Contact | Company | Type | Topic | Last | Status |
|---|-------------|----------|----------|----------------------|-------|-------------------|
| 1 | Sarah Chen | Sequoia | Investor | Series A term sheet | Jun 6 | 🔴 Waiting on me |
| 2 | Marcus Webb | Stripe | Partner | API integration call | Jun 6 | 🟢 Active |
| 3 | Priya Patel | Notion | Customer | Enterprise pilot | Jun 5 | 🔴 Waiting on me |
## Your Action Items
- [ ] Send the updated cap table — Sarah Chen re: Series A (due Fri)
- [ ] Reply with pilot timeline — Priya Patel re: Notion pilot
- Two-way only. It anchors on threads you actually replied to or that got a reply — not cold outreach, not blasts.
- Ruthless noise filtering.
noreply@, newsletters (List-Unsubscribe), and automated domains are dropped in code. - Actually actionable. Relationship type, status, deadlines, and action items — not just a list of names.
- Private by default. Read-only Gmail, processed in your own client / on your machine. No Circuit server sees your mail.
- Free and open. MIT. The skill and the engine cost nothing to run.
Skill (Claude Code):
claude plugin marketplace add circuitcx/circuit
claude plugin install circuit@circuit
/circuitOptional local engine (any MCP client):
export CIRCUIT_GOOGLE_CLIENT_ID=... CIRCUIT_GOOGLE_CLIENT_SECRET=...
npx -y circuitcx auth # one-time, read-only Gmail consentFull setup — including the zero-Google-Cloud path via Claude's Gmail connector — is in docs/quickstart.md.
Skill (/circuit) |
+ MCP server (circuitcx) |
|
|---|---|---|
| Install | plugin / copy to ~/.claude/skills |
npx -y circuitcx |
| Gmail access | Claude's Gmail connector | your own Google OAuth (read-only) |
| Google Cloud setup | none | ~10 min, one time |
| Speed | good | faster (engine runs in code) |
| Works in | Claude Desktop / Claude Code | any MCP client |
The skill auto-detects the MCP server and uses it when present; otherwise it falls back to the Gmail connector. See install-skill.md and install-mcp-server.md.
/circuit ── the skill (this repo, skills/circuit)
│ classifies type + status, extracts deadlines & action items
▼
Claude (your AI client)
│ calls a Gmail tool:
├──────────────► circuitcx server ──► Gmail API (read-only)
│ deterministic engine (this repo, mcp-server/)
└──────────────► Claude Gmail connector ──► Gmail API (read-only)
The deterministic engine (two-way detection + noise filtering + thread assembly) is the reusable, unit-tested core. Classification is delegated to your AI client — so the open-source tier needs no LLM key and is free to run. More →
Circuit is open core. This repo is the free tier. The hosted app adds the convenience layer.
| Free (this repo) | Hosted | |
|---|---|---|
/circuit skill + local engine |
✅ | ✅ |
| Runs on demand in Claude | ✅ | ✅ |
| Always-on background sync | — | ✅ |
| Web dashboard + history | — | ✅ |
| Calendar enrichment | — | ✅ |
| Managed — no setup | — | ✅ |
circuit/
├── skills/circuit/SKILL.md the /circuit skill (classification + output)
├── mcp-server/ circuitcx — deterministic Gmail engine (npm)
│ ├── src/core/ pure, unit-tested filters + two-way detection
│ └── src/gmail/ Gmail REST client + OAuth
├── docs/ setup, connect-gmail, how-it-works, faq
└── examples/ client config snippets + sample output
Issues and PRs welcome — see CONTRIBUTING.md. The pure engine in mcp-server/src/core/ is the best place to start, and it's covered by tests (npm test).
Read-only scope; nothing leaves your machine on the open-source path. Report vulnerabilities per SECURITY.md.
MIT © Circuit