mnemopay-sdk: Cursor rule for Cursor

You are an expert in TypeScript, Node.js, MCP (Model Context Protocol), and AI agent financial infrastructure.

Core Rules

• This is a financial SDK — correctness > cleverness. Never approximate money.
• All amounts are numbers (not strings). Use penny-precise arithmetic where needed.
• Never break the public API surface (exports from src/index.ts).
• Tests run with vitest. Run npm test before any PR.
• Build with npm run build (tsc). Fix type errors before committing.

Architecture

• src/index.ts — Main SDK class (MnemoPay, MnemoPayLite, MnemoPayNetwork) + all type exports (~74KB)
• src/fico.ts — Agent FICO credit scoring (300-850, 5 components)
• src/behavioral.ts — Behavioral finance (prospect theory, hyperbolic discounting, cooling-off)
• src/integrity.ts — Merkle tree memory integrity (SHA-256, tamper detection)
• src/anomaly.ts — EWMA anomaly detection + BehaviorMonitor + CanarySystem
• src/adaptive.ts — Adaptive engine (AIMD, anti-gaming, circuit breaker, PSI drift)
• src/commerce.ts — CommerceEngine (autonomous shopping with mandates)
• src/fraud.ts — Geo-enhanced fraud detection (country tracking, rapid-hop, currency mismatch)
• src/fraud-ml.ts — ML fraud scoring
• src/identity.ts — IdentityRegistry, AgentIdentity, CapabilityToken, KYA
• src/ledger.ts — Double-entry ledger (always balances to zero)
• src/network.ts — Multi-agent commerce network
• src/client.ts — REST client for remote MnemoPay server
• src/mcp/ — MCP server (24 tools, 2 prompts, SSE endpoint)
• src/rails/ — Payment rails (Stripe, Paystack, Lightning, Mock)
• src/recall/ — Recall engine (score, vector, hybrid strategies)
• src/storage/ — Storage adapters (SQLite, in-memory)
• src/middleware/ — OpenAI and Anthropic middleware
• src/langgraph/ — LangGraph tool bindings
• src/cli/ — CLI tools (setup, dashboard)

Two Modes

• MnemoPay.quick("id") → zero infra, in-memory (dev/testing)
• MnemoPay.create({...}) → full config (production)

Key Patterns

• EventEmitter for lifecycle events (charge, settle, refund, fraud-alert, etc.)
• All payment operations: charge → settle/refund (two-phase commit)
• Agent FICO: payment history 35%, utilization 20%, age 15%, diversity 15%, fraud 15%
• Fee tiers based on FICO: 1.0% (800+), 1.3% (740+), 1.5% (670+), 1.9% (580+), 2.5% (<580)
• Merkle proofs for memory tamper detection
• EWMA for streaming anomaly detection

Testing

• 672+ tests across 12 test files in tests/
• Use vitest: npm test (run all), npm run test:watch (dev mode)
• Test files mirror src/ structure: tests/index.test.ts, tests/fico.test.ts, etc.
• Always test edge cases: zero amounts, negative values, overflow, concurrent access

MCP Server

• 24 tools: remember, recall, forget, reinforce, consolidate, charge, settle, refund, balance, profile, logs, history, reputation, dispute, fraud_stats, shop_set_mandate, shop_search, shop_buy, shop_confirm_delivery, shop_orders, agent_fico_score, behavioral_analysis, memory_integrity_check, anomaly_check
• 2 prompts: recall-and-decide, agent-status-report
• Auth: Bearer token via MNEMOPAY_API_KEY (constant-time comparison)
• Rate limiting: 60 calls/min, 500 calls/hour
• Entry: src/mcp/server.ts

Dependencies

• Runtime: @modelcontextprotocol/sdk, express
• Peer (optional): openai, @anthropic-ai/sdk, @langchain/*, zod, stripe, better-sqlite3
• Dev: typescript, vitest, @langchain/core

Common Mistakes

• Forgetting to call settle() after charge() — leaves transactions pending forever
• Using string amounts instead of numbers
• Not handling the HITL (human-in-the-loop) flag from FICO scoring
• Ignoring fraud risk assessments on cross-border transactions
• Breaking EventEmitter contracts (listeners expect specific event shapes)

Deployment

• npm: @mnemopay/sdk
• PyPI: mnemopay (Python SDK, separate codebase)
• MCP: Smithery registry
• Landing: site/index.html
• Fly.io: mnemopay-mcp.fly.dev

Docs: https://github.com/mnemopay/mnemopay-sdk