Artificial Intillegence » Zelle Payment for evergreen

Installing Python and Installing VS Code / Cursor and Installing the required libraries

Project Structure
payment-system/
├── app/ # Core application code
│ ├── init.py
│ ├── main.py # FastAPI entrypoint
│ ├── routers/ # API routes grouped by domain
│ │ ├── payments.py # Payment endpoints (send, receive, reversal)
│ ├── db.py # DB connection (SQLAlchemy, asyncpg, etc.)
│ ├── models.py # SQLAlchemy models / Pydantic schemas
│
├── mock_zelle/ # Mock Zelle partner server
│ ├── init.py
│ └── mock_server.py # Endpoints: initiate, receive, reversal
│
├── docker-compose.yml # Containers for FastAPI, DB, Mock Zelle
└── requirements.txt # Python dependencies

1. Separation of Concerns:
app/ handles main service logic.
mock_zelle/ cleanly isolates the simulated Zelle partner.

2.Scalable API Design
routers/ lets you add more modules later (e.g., users.py, reconciliation.py).
main.py can include app.include_router(...) calls.

3.Database Layer
db.py centralizes DB connection setup.
models.py holds ORM models + Pydantic schemas (clean separation).

4.Deployment Ready
docker-compose.yml can run FastAPI + PostgreSQL + Mock Zelle API in containers.
requirements.txt makes environment reproducible.

5.Mock Partner for Testing
mock_server.py simulates Zelle’s APIs → avoids compliance issues while testing.

Estimated Time Breakdown (16–24 Hours Total)
1.FastAPI Service Setup (5–6 hours)
Create base FastAPI app.
Define endpoints for send_payment, receive_payment, and reversal.
Add request/response models with Pydantic.
Test locally with uvicorn.

2.Database Schema (4–6 hours)

Setup PostgreSQL connection.
Define schema: payments, reconciliations, audit_logs.
Create migrations (Alembic).
Test read/write transactions.

3.Simulated Zelle Partner API (5–6 hours)
Create mock server (FastAPI or Flask).
Expose endpoints /initiate, /receive, /reversal.
Handle request/response with realistic delays.
Add logging for partner calls.

4.Integration & Testing (2–4 hours)
Connect FastAPI → DB → Simulated Zelle partner.
End-to-end flow: Initiate → Confirm → Reversal.
Verify logs and reconciliation records.

-------------------- | Customer Checkout |
-------------------- |
v
----------------------------- | POS Generates: | | - Amount | | - Zelle Recipient (email) | | - Unique Ref Code (e.g. TX1234) |
----------------------------- |
v
------------------------------------- | Display Payment Instructions to User |
------------------------------------- |
v
------------------------------------ | Customer Sends Payment via Zelle | | - To your email/phone | | - Includes TX1234 in memo (optional) |
------------------------------------ |
v
----------------------------- | Wait for Plaid to Poll Bank | | (every 15–60 seconds) |
----------------------------- |
v
----------------------------------------- | Plaid Receives New Bank Transactions | | - Looks for Incoming Credits | | - Filters by: | | • Amount | | • Time Window | | • Description contains "Zelle" and TX1234 |
----------------------------------------- |
------+ | |
v v
---------------------- ----------------------- | ✅ Match Found | | ❌ No Match Yet |
---------------------- ----------------------- | - Mark POS as Paid | | - Keep Polling (timeout)| | - Print receipt | | - Notify cashier |
---------------------- -----------------------

Customer → Sends Zelle Payment (Chase/Zelle)
↓
Chase Account → Transaction Created
↓ (Webhook)
Plaid → Detects Transaction + Notifies Your Server
↓
Backend → Match Ref Code / Amount
↓
Order System → Mark as Paid

The Estimated time was exceeded because of the errors it was delayed