The AI code editor built for deep code understanding. ChooChoo generates .cursor/rules so every AI suggestion in Cursor follows your team's patterns — consistently, across the entire team.
Cursor's rules files define how the AI suggests and generates code. ChooChoo compiles them from your real codebase — so AI suggestions reflect your actual standards, not a snapshot from six months ago.
.cursor/rules with required patterns and prohibited anti-patterns
Auto-updated when your linting config, ADRs, or standards change
Committed to git so the whole team stays in sync
---
description: Project rules for payments-api
globs: ["**/*.py", "**/*.ts"]
alwaysApply: true
---
# Code Standards
You are working on payments-api, a FastAPI service
handling financial transactions. Follow these rules
in all code suggestions and completions.
## Required Patterns
- Use get_db() dependency for all database access
- Validate all inputs with Pydantic before DB writes
- Return typed response schemas from all endpoints
- Full type annotations on all new functions
## Prohibited Patterns
- No raw SQL strings — use SQLAlchemy ORM only
- No print() in production code — use logger
- Never log PII, card numbers, or auth tokens
## Security
- Rate limiting required on all public endpoints
- API keys from environment variables only
- Parameterize all database queries
# SKILLS.md
# Generated by ChooChoo — do not edit by hand.
## auth
JWT token lifecycle: creation, validation, refresh.
Entry: src/auth/service.py
Tests: tests/auth/
## payments
Stripe integration: charges, subscriptions, webhooks.
Entry: src/payments/processor.py
Note: Never log STRIPE_KEY or card numbers
## database
SQLAlchemy sessions and query patterns.
Entry: src/db/session.py
Rule: Always use get_db() dependency injection
## notifications
Email (SendGrid) and SMS (Twilio) dispatch.
Entry: src/notifications/dispatch.py
# PLAN.md
# Generated by ChooChoo — do not edit by hand.
## Goal
Refactor the authentication service to support
multi-factor authentication (MFA) via TOTP.
## Steps
1. [ ] Add TOTP secret column to users table
migration: src/db/migrations/0023_add_totp.py
2. [ ] Implement TOTP validation in auth service
src/auth/service.py → verify_totp()
3. [ ] Add /auth/mfa/setup and /auth/mfa/verify routes
src/api/auth.py
4. [ ] Write unit tests for new MFA paths
tests/auth/test_mfa.py (≥ 90% coverage)
5. [ ] Update AGENTS.md with new ADR-012
## Constraints
- Do not break existing JWT flow (ADR-001)
- TOTP secrets encrypted at rest (AES-256)
- Rate-limit /auth/mfa/verify to 5 attempts / 15 min
# ARCHITECTURE.md
# Generated by ChooChoo — do not edit by hand.
## System Overview
payments-api is a stateless FastAPI service.
All state lives in PostgreSQL (primary data) and
Redis (sessions, rate limiting, event streams).
## Request Flow
Client → API Gateway → FastAPI → Service Layer
→ Repository Layer
→ PostgreSQL / Redis
## Key Modules
src/auth/ JWT issuance + TOTP (ADR-001, ADR-012)
src/payments/ Stripe integration (charges, webhooks)
src/db/ SQLAlchemy sessions + migration runner
src/api/ Route definitions (v1 + v2 namespaces)
## ADR Index
ADR-001 RS256 JWT for authentication
ADR-004 Redis Streams for webhook event bus
ADR-007 URL versioning (/v1/, /v2/)
ADR-012 TOTP-based MFA (in progress)
## Deployment
Docker → ECS Fargate (app)
RDS PostgreSQL 15 (primary)
ElastiCache Redis 7 (cache + streams)
# GOAL.md
# Generated by ChooChoo — do not edit by hand.
## Current Sprint Goal
Implement MFA support without breaking existing
single-factor authentication flows.
## Success Criteria
- All existing auth tests continue to pass
- New /auth/mfa/* endpoints return correct responses
- TOTP validation rejects tokens older than 30 s
- Coverage for src/auth/ stays above 90%
## Out of Scope
- SMS-based MFA (deferred to ADR-013)
- Admin UI for MFA management (separate ticket)
- Recovery codes (phase 2)
## Definition of Done
- PR reviewed and approved
- CI green (lint + test + coverage)
- AGENTS.md updated with ADR-012 summary
- Deployed to staging and smoke-tested
flowchart TD
A([Client Request]) --> B[API Gateway]
B --> C{JWT Valid?}
C -- Yes --> D[FastAPI Router]
C -- No --> E([401 Unauthorized])
D --> F[Service Layer]
F --> G[Repository]
G --> H[(PostgreSQL)]
G --> I[(Redis)]
F --> J[Stripe API]
J --> K[Webhook Event]
K --> L[(Redis Streams)]
Why use ChooChoo with Cursor?
Cursor is only as good as the rules you give it. ChooChoo writes those rules from your actual codebase.
Consistent Output
Generated code follows your linting rules from the start, reducing cleanup work before code review.
Fewer Iterations
The AI understands your standards upfront, producing acceptable code faster and with less back-and-forth.
Team Alignment
Everyone's AI assistant generates code that matches your team's style guide — automatically.
Zero Configuration
Get started instantly with sensible defaults that work out of the box for most projects.
Type-Safe Code
Strict linting rules catch potential bugs and enforce type safety before they reach review.
AI-Ready Rules
Purpose-built rules that AI models understand and follow consistently, session after session.
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