Circulara Core MCP Server

circulara-core

Circulara Observe tier: per-tenant backend + MCP plugin. Sprints 1-4: WS0 (scaffold), WS6 (pricing registry), WS1 (MCP plugin), WS2 (auth + BYO keys + gateway), WS3 (telemetry pipeline: normalize -> re-price -> append; free-tier cap; OpenAI-format gateway for Cursor-class hosts), WS4 (meter compute: registry pricing, energy/CO2e ranges with confidence labels, per user/team/module/month report), WS5 (Observe dashboard + savings-potential report + monthly statement, server-rendered, Ledger Light brand tokens; seed a demo tenant with packages/backend/scripts/seed-demo.ts and open the printed /dashboard URL). Architecture: /outputs/reports/architecture_v1.md (AD1-AD6, rev 2026-07-07) + the sourcing addendum (AD7-AD12).

Pricing placement: the meter owns money. All three capture paths (hook, tool, gateway) deliver tokens + model; pricing happens ONCE in the WS3/WS4 pipeline from the approved registry snapshot. Client-submitted observe events are re-priced server-side; client cost is a hint, never the booked number. Engine-computed events (reuse/sourcing, waves 3+) carry their own math and are born meter-priced in-process.

Workspace layout

Run

npm install
npm test              # all workspaces: backend 11 + plugin 4 (in-memory, no keys)
npm run typecheck
npm run dev           # backend on 127.0.0.1:8787 (CIRCULARA_AUTH_MODE=dev|oidc)

# WS6 registry flow (human approves diffs, D12):
npm run registry -- update|approve|show

# WS2 LIVE smoke (deliberate; ~cents on the configured Anthropic key):
cd packages/backend && npx tsx scripts/live-smoke.ts

Auth (WS2)

• Humans: OIDC/SSO (RS256 vs org issuer JWKS; admin via circulara_role=admin claim).
• Named agents: short-lived HS256 seat tokens minted at POST /v1/seats/:id/token (admin).
• Dev mode ONLY with CIRCULARA_AUTH_MODE=dev: Bearer dev-admin-token / dev-seat-token.
• Gateway (M2): per-seat credentials from POST /v1/seats/:id/gateway-credential; the host sends the credential as x-api-key to POST /gateway/anthropic/v1/messages; backend maps credential -> seat, forwards on the tenant's real key, meters per seat.

MCP plugin install (Claude Code)

claude mcp add circulara \
  -e CIRCULARA_BACKEND_URL=http://127.0.0.1:8787 \
  -e CIRCULARA_TENANT_ID=<uuid> -e CIRCULARA_TOKEN=<bearer> \
  -e CIRCULARA_SEAT_ID=<uuid> -e CIRCULARA_USER_ID=<sso-subject> \
  -- npx tsx <repo>/packages/plugin/src/server.ts

Hook capture (path A): wire packages/plugin/src/hook.ts as a PostToolUse hook (see file header). The hook never fails the host tool call.

Invariants the tests enforce

• Tenant isolation; append-only meter_events; admin-only agent seats (AD6).
• avoided_usd == counterfactual - actual; sourcing types require the v1.1 block; M1 call_id chaining telescopes per-call savings.
• Provider keys never at rest in plaintext (envelope AES-256-GCM, wrong-KEK/tamper throw); write-only API (names listed, values never returned).
• Gateway: unknown credential 401; missing tenant key 503; per-seat attribution exact; registry-priced usage.
• OIDC: wrong issuer rejected; dev tokens rejected outside dev mode; agent tokens expire.

Keys

Runtime keys come ONLY from the external env file via loadSecret() (path in src/config.ts, names in /context/api.md): CIRCULARA_MASTER_KEY (envelope KEK), CIRCULARA_AGENT_TOKEN_SECRET (agent JWTs), tenant provider keys via the API. Never hardcoded, never logged, never committed.