SESSION HANDOFF SUMMARY
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Date: 2026-04-25
Session Duration: ~2 hours
Project: Express.js API

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COMPLETED WORK
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1. JWT Authentication Middleware
   - File: src/middleware/auth.ts
   - Status: Done, with known issue (see below)

2. Route Handlers
   - /users route handler — complete
   - /posts route handler — complete

3. Unit Tests
   - Unit tests for /users — complete
   - Unit tests for /posts — complete

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KNOWN ISSUE
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Location: src/middleware/auth.ts
Description: Token refresh is not handled. When a JWT is expired, the
middleware returns 401 even if the client has a valid refresh token.
The correct behavior should be: detect expired token, check for valid
refresh token, issue new access token, and continue the request.

Impact: Mobile app clients that rely on refresh token flows will be
logged out on token expiry instead of receiving a refreshed token
transparently.

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PENDING WORK
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Priority order based on dependencies:

1. Token Refresh Logic (src/middleware/auth.ts)
   - Detect token expiration separately from other JWT errors
   - Extract and validate the refresh token from the request
   - Issue a new access token and attach it to the response
   - Continue processing the original request
   - CONSTRAINT: Response shape must stay compatible with the existing
     mobile app client — do not change response envelope structure or
     field names

2. Rate Limiting for /posts Endpoint
   - Add rate limiting middleware to the /posts route only
   - Choose an appropriate window and request limit
   - Ensure rate-limit error responses match the existing response shape
     expected by the mobile client

3. Integration Tests
   - Cover the full request lifecycle (auth middleware + route handlers)
   - Include scenarios: valid token, expired token + valid refresh,
     expired token + invalid refresh, rate limit exceeded
   - These depend on items 1 and 2 being complete first

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CONSTRAINTS
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- The existing mobile app client expects the current response shape.
  All changes must preserve the existing response envelope and field names.
  Verify any new error responses (401, 429, etc.) match the shape the
  client already handles.

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CONTEXT FOR NEXT SESSION
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- auth.ts already has the JWT verification logic in place; the gap is
  specifically the refresh-token branch that is missing.
- Unit tests for routes already pass — do not break them.
- Integration tests are net-new and should be added after pending features
  are implemented.
- No database schema changes should be needed for the above tasks.
