Payment Reconciliation Copilot

A small, safety-bounded MCP server for operations investigations such as “I was charged twice” and “my refund never arrived.” It turns normalized payment-event data into an auditable timeline, detects defined reconciliation anomalies, and creates a human-review escalation. It never executes, retries, captures, voids, or refunds payments.

Try the hosted service

The hosted deployment contains synthetic data only. Configure any MCP client that supports Streamable HTTP with the /mcp URL. Client configuration syntax varies; conceptually:

{
  "mcpServers": {
    "payment-reconciliation": {
      "url": "https://transactions-mcp.onrender.com/mcp"
    }
  }
}

After connecting, ask the client or its LLM:

Investigate the duplicate-charge complaint for ORD-DUP-001. Use the connected tools, propose a resolution, and do not execute a payment action.

Related MCP server: mcp-paypal

What it does

1. Finds a transaction from an order ID, customer email, or amount plus date range.

2. Returns its normalized event timeline and any payload conflicts.

3. Detects duplicate-charge, stuck-refund, and out-of-order-webhook evidence.

4. Produces one diagnostic escalation per anomaly for human review.

The design is intentionally read-heavy. Only anomalies and escalations may be written; transactions, provider state, and payment state are never changed by MCP tools.

MCP tools

Data model and idempotency

The database, not application memory, enforces the important guarantees:

evidence_hash is generated from canonically ordered evidence event IDs and the detection window. This makes detection retries safe while allowing new evidence to produce a separate anomaly.

Demo scenarios

The synthetic seed contains 24 transactions across MockStripe and MockAdyen:

For the duplicate case, call detect_anomaly twice and then call propose_resolution twice. The anomaly and escalation IDs should remain stable across retries.

Run locally

Prerequisites

• Node.js 20+

• PostgreSQL database dedicated to this synthetic demo

Setup

npm ci
Copy-Item .env.example .env
# Set DATABASE_URL in .env to a disposable local/development Postgres database.
npm run db:migrate
npm run db:seed

Warning: npm run db:seed deletes all records in this project’s six tables before rebuilding the deterministic synthetic fixtures. Never run it against real, shared, or production-like data.

Commands

npm run dev                 # Local development server with tsx watch
npm run build               # Emit production JavaScript to dist/
npm run start               # Run compiled production server
npx tsc --noEmit            # Strict type check
npm run test -- --run       # Focused integration suite
npm run db:generate         # Generate a Drizzle migration after schema changes
npm run db:migrate          # Apply pending migrations
npm run db:seed             # Reset and seed the synthetic database

Local endpoints are http://localhost:3000/, /health, and /mcp.

Test and verification

The focused integration suite uses the real disposable Postgres database and resets synthetic fixtures before each test:

npm run test -- --run

It verifies:

• find_transaction rejects ambiguous input and does not change mutable records.

• get_transaction_timeline returns linked payload conflicts without writes.

• Calling detect_anomaly repeatedly returns one anomaly for the same evidence.

• Calling propose_resolution repeatedly returns one escalation, including after escalation status changes.

For hosted verification, connect an MCP client to the deployed /mcp URL and run the duplicate-charge workflow in Demo scenarios. The deployment was also exercised through an LLM-connected MCP client.

Deployment

The service is deployed to Render as a Node web service. Its production build compiles TypeScript before starting Node:

Build command: npm ci --include=dev && npm run build
Start command: npm run start
Health check: /health

Runtime variables required by the service:

DATABASE_URL=<isolated synthetic/demo PostgreSQL connection string>
NODE_ENV=production
DB_POOL_MAX=3

Do not run the destructive synthetic seed automatically on every deployment. Apply migrations and seed a new isolated demo database deliberately.

Project layout

src/db/                 Drizzle schema, pooled client, and deterministic seed
src/reconciliation/     Lookup, timeline, anomaly, and escalation behavior plus tests
src/mcp/                MCP server and tool registrations
src/index.ts            Streamable HTTP endpoint, welcome/health routes, shutdown handling
drizzle/                Generated SQL migrations
ASSUMPTIONS_AND_EXCLUSIONS.md
AI_WORKLOG.md
WALKTHROUGH_SCRIPT.md

Submission assets

• Assumptions and exclusions

• AI worklog

Safety reminder

This is a synthetic-data demonstration. The public endpoint is unauthenticated by intentional assignment scope, so it must never be pointed at real customer, transaction, or payment-provider data.