# Fix Login Issue - Expired JWT Tokens

## Problem
You're seeing this error when trying to log in:
```
INFO:     127.0.0.1:58687 - "POST /auth/refresh HTTP/1.1" 401 Unauthorized
🔐 JWT decode error: Signature has expired.
```

This happens because the JWT refresh token stored in your browser's localStorage has expired.

## Quick Fix - Option 1: Use the Clear Tokens Page

1. Open your browser and navigate to: `frontend/clear-tokens.html`
2. Click the "Clear Expired Tokens" button
3. Navigate to http://localhost:5173/login
4. Log in with your credentials

## Quick Fix - Option 2: Clear Tokens Manually

Open your browser's Developer Console (F12) and run:
```javascript
localStorage.removeItem('access_token')
localStorage.removeItem('refresh_token')
location.reload()
```

## Quick Fix - Option 3: Clear Browser Data

1. Open Developer Tools (F12)
2. Go to Application tab (Chrome) or Storage tab (Firefox)
3. Find Local Storage → http://localhost:5173
4. Delete `access_token` and `refresh_token`
5. Refresh the page

## What Was Fixed

### 1. Enhanced Token Validation
Added `validateTokens()` method to the auth store that:
- Decodes JWT tokens to check expiration
- Automatically clears tokens that are more than 7 days expired
- Prevents the app from trying to use invalid tokens

### 2. Improved Error Handling
Updated the API interceptor to:
- Better handle expired refresh tokens
- Prevent infinite retry loops
- Only redirect to login when appropriate
- Add logging for debugging

### 3. Startup Token Validation
Modified `main.ts` to:
- Validate tokens before initializing auth
- Clear expired tokens automatically on app startup
- Prevent 401 errors during initialization

## Code Changes

### frontend/src/stores/auth.ts
- Added `validateTokens()` method
- Improved error logging in `refreshAccessToken()`
- Better error handling in `initializeAuth()`

### frontend/src/services/api.ts
- Enhanced response interceptor
- Added check to prevent retrying refresh endpoint
- Better error logging
- Improved redirect logic

### frontend/src/main.ts
- Added token validation on app startup
- Calls `validateTokens()` before `initializeAuth()`

## Prevention

The updated code now:
1. **Validates tokens on startup** - Clears expired tokens automatically
2. **Better error handling** - Logs errors instead of silently failing
3. **Prevents retry loops** - Won't retry the refresh endpoint itself
4. **Graceful degradation** - Clears tokens and redirects to login on failure

## Testing

After clearing tokens, test the following:
1. ✅ Can log in with valid credentials
2. ✅ Access token is stored in localStorage
3. ✅ Refresh token is stored in localStorage
4. ✅ Can navigate to protected routes
5. ✅ Token refresh works when access token expires
6. ✅ Logout clears tokens properly

## Future Improvements

Consider implementing:
1. **Token expiration warnings** - Notify users before tokens expire
2. **Automatic token refresh** - Refresh tokens proactively before expiration
3. **Remember me** - Longer-lived refresh tokens for persistent sessions
4. **Session management** - Server-side session tracking
