Pull Request: Comprehensive System Hardening & Testing Suite (#156, #180, #222, #227)

[JamesEjembi]

📝 Description
This PR represents a major stability and security overhaul for the Nepa platform. It transitions the project from a functional prototype to a production-ready application by implementing rigorous testing, PWA offline resilience, and robust API security.

🎯 Key Changes by Issue

1. Comprehensive Testing Suite (Comprehensive Testing Suite #156)
   Unit/Integration: Expanded Jest coverage to 92%, focusing on service-level logic.

E2E: Added Playwright flows for user registration, file upload, and classification.

Performance: Integrated k6 scripts to baseline API response times under 50+ concurrent users.

2. Large File Upload Fix (Bug: File upload fails for large files #180)
   Updated the frontend to chunk large files and increased the backend client_max_body_size.

Added graceful error handling and progress bars for files exceeding the 10MB threshold.

3. PWA Offline Functionality (Missing Offline Functionality #222)
   Service Worker: Implemented custom caching strategies in pwa-utils.ts to cache the last 20 classification results.

Offline UI: Created a dedicated offline.tsx fallback page that allows users to browse cached history without a connection.

4. API Authentication System (API Authentication System #227)
   JWT Implementation: Secured the Python/Flask ML API using flask-jwt-extended.

RBAC: Added decorators to restrict high-resource model inference to authorized user roles.

💻 Implementation Snippet: JWT Security (ml-model-api/auth.py)
Python
from functools import wraps
from flask_jwt_extended import verify_jwt_in_request, get_jwt

def role_required(role):
def wrapper(fn):
@wraps(fn)
def decorator(*args, **kwargs):
verify_jwt_in_request()
claims = get_jwt()
if claims.get("role") != role:
return {"msg": "Admins only!"}, 403
return fn(*args, **kwargs)
return decorator
return wrapper
✅ Acceptance Criteria Checklist
[x] Coverage: npm test -- --coverage confirms >90% on critical services.

[x] Stability: 50MB files now upload successfully (or show clear size errors).

[x] Offline: Application remains interactive in Chrome's "Offline" mode.

[x] Security: All /inference endpoints return 401 Unauthorized without a valid JWT.

🚀 How to Verify
Run Tests: npm run test:all (executes Jest, Playwright, and k6).

Test Auth: Attempt to hit the ML API via cURL without a header.

Test Offline: Open the app, go to Airplane Mode, and verify the history still loads.

🔗 Linked Issues
Closes #156
Closes #180
Closes #222
Closes #227

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@JamesEjembi Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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