PayPal Sandbox Skill

This skill ensures that all local payment testing is safely isolated in the PayPal Sandbox environment.

1. Environment Configuration

To enable Sandbox mode, ensure your .env.local (or server environment) has the following variables set:

# Set to SANDBOX for testing, LIVE for production
PAYPAL_ENVIRONMENT=SANDBOX

# Sandbox Credentials (from developer.paypal.com)
PAYPAL_CLIENT_ID_SANDBOX=your_sandbox_client_id
PAYPAL_CLIENT_SECRET_SANDBOX=your_sandbox_client_secret

# Optional: Override return URLs for local testing
PAYPAL_RETURN_URL_SANDBOX=http://localhost:3000

Critical Implementation Note

When loading environment variables in local-server.js, ALWAYS load .env.local BEFORE .env. dotenv does not overwrite existing keys. If you load .env (Live) first, it will LOCK the environment to Live, ignoring your local Sandbox overrides.

Correct Order:

dotenv.config({ path: resolve(__dirname, '.env.local') }); // Loads Sandbox/Overrides FIRST
dotenv.config({ path: resolve(__dirname, '.env') });       // Loads Defaults SECOND

2. Local Server Port Rule (CRITICAL)

ALWAYS use port 3000 for local development. If port 3000 is already in use, you MUST:

1. •

   Kill the existing process on port 3000:

   bash

   lsof -ti:3000 | xargs kill -9 2>/dev/null || true
   

2. •

   Then start the dev server on port 3000:

   bash

   npm run dev -- --port 3000
   

Why this matters:

• •PayPal sandbox redirect URLs are configured for localhost:3000
• •Vite will automatically pick a different port (e.g., 3001) if 3000 is busy, breaking PayPal redirects
• •The entire payment flow assumes port 3000

3. Testing Workflow

3.1 Sanity Check

Before testing, verify the API is hitting the sandbox endpoint:

• •https://api.sandbox.paypal.com (NOT api.paypal.com)

3.2 Test Accounts

Use "Personal" and "Business" sandbox accounts created at developer.paypal.com.

• •Personal Account: Use this to "buy" items in your local shop.
• •Business Account: This is the "merchant" account receiving the fake funds.

3.3 Verification

1. •Ensure the "Secure Checkout" button redirects to sandbox.paypal.com.
2. •Complete a test transaction using the personal sandbox account.
3. •Verify that the redirect back to /payment/success works correctly on localhost.

4. Critical Rules

• •NEVER use real credit card numbers in the sandbox.
• •NEVER set PAYPAL_ENVIRONMENT=LIVE in a local .env.local file.
• •If a 401 Unauthorized occurs, refresh your Sandbox client credentials.
• •Ensure localhost:3000 is added as a valid redirect URI in your PayPal app settings if using OAuth.

5. Automated Testing & Bot Protection (Mitigation Strategy)

PayPal aggressively blocks automated browsers (used by AI agents), often resulting in a "You have been blocked" screen during testing. This does NOT mean the feature failed.

Symptom

• •Automated browser redirects to PayPal but shows a generic "Blocked" or "Security Challenge" message.
• •URL is correct: https://www.paypal.com/checkoutnow?token=... or https://www.sandbox.paypal.com/...

Validation Strategy (If Blocked)

Do not attempt to bypass the block. Instead, validate the success based on the handoff state:

1. •Check URL Structure: If the browser reached paypal.com with a valid ?token=... query parameter, the Application <-> PayPal handshake was SUCCESSFUL.
2. •Confirm API Handoff: The presence of the token proves the backend successfully authenticated, created an order, and received a redirect URL.
3. •Report Success: Inform the user that the "Blocked" screen is an expected artifact of automated testing. Direct the user to copy the URL into a regular browser to verify the visual interface.

Example Report:

"The checkout flow is functioning correctly. The backend successfully initiated the session, and the browser redirected to PayPal with a valid token (token=...). The 'Blocked' screen is expected when using an automated agent. Please verify the visual checkout by determining the URL in a standard browser."