# Notification System Fixes - Implementation Summary

**Date**: 2026-01-06  
**Status**: ✅ All fixes implemented

---

## ✅ **Fix #1: Redis Caching for Leantime User ID**

### **Problem**:
- `getLeantimeUserId()` fetched ALL users from Leantime API every time
- No caching, causing slow performance and inconsistent results
- Race conditions between different calls

### **Solution**:
- Added Redis caching with 1-hour TTL
- Cache key: `leantime:userid:${email.toLowerCase()}`
- Checks cache first before making API call
- Caches result after successful fetch

### **Implementation**:
- **File**: `lib/services/notifications/leantime-adapter.ts`
- **Method**: `getLeantimeUserId()`
- **Cache TTL**: 3600 seconds (1 hour)
- **Static helper**: `invalidateUserIdCache()` for manual cache clearing

### **Benefits**:
- ✅ Faster performance (no API call if cached)
- ✅ More reliable (consistent results)
- ✅ Reduced API load on Leantime
- ✅ Better error recovery (can use cached value if API fails)

---

## ✅ **Fix #2: Retry Logic with Exponential Backoff**

### **Problem**:
- `getLeantimeUserId()` failed immediately on API errors
- No retry mechanism for transient failures
- Network errors caused permanent failures

### **Solution**:
- Added retry logic with up to 3 retries
- Exponential backoff: 1s, 2s, 4s (max 5s)
- Retries on:
  - Server errors (5xx)
  - Rate limiting (429)
  - Network errors
  - Certain JSON-RPC errors

### **Implementation**:
- **File**: `lib/services/notifications/leantime-adapter.ts`
- **Method**: `getLeantimeUserId()` with `fetchWithRetry()`
- **Max Retries**: 3
- **Backoff**: Exponential (1s → 2s → 4s)

### **Benefits**:
- ✅ Handles transient failures gracefully
- ✅ Better resilience to network issues
- ✅ Improved success rate for user ID lookup

---

## ✅ **Fix #3: Always Invalidate Cache After Marking**

### **Problem**:
- Cache only invalidated if marking operation succeeded
- If `getLeantimeUserId()` failed, cache stayed stale
- Count remained at old value (65) even after marking attempts

### **Solution**:
- Always invalidate cache after marking attempt
- Even if operation failed or returned `false`
- Ensures fresh data on next fetch

### **Implementation**:
- **File**: `lib/services/notifications/notification-service.ts`
- **Methods**: 
  - `markAsRead()` - Always invalidates cache
  - `markAllAsRead()` - Always invalidates cache
- **Logic**: Cache invalidation happens regardless of success/failure

### **Benefits**:
- ✅ Count always refreshes after marking attempts
- ✅ User sees accurate data even if operation partially failed
- ✅ Better UX (no stale count stuck at 65)

---

## ✅ **Fix #4: Improved Count Accuracy**

### **Problem**:
- Count only based on first 100 notifications
- If user had >100 notifications, count was inaccurate
- Used cached notifications which might be stale

### **Solution**:
- Fetch up to 1000 notifications directly from API for counting
- Bypasses cache to get fresh data
- More accurate count for users with many notifications

### **Implementation**:
- **File**: `lib/services/notifications/leantime-adapter.ts`
- **Method**: `getNotificationCount()`
- **Change**: Fetches directly from API (up to 1000) instead of using cached `getNotifications()`
- **Warning**: Logs if count reaches 1000 (might have more)

### **Benefits**:
- ✅ More accurate count (up to 1000 notifications)
- ✅ Fresh data (bypasses cache)
- ✅ Better handling of users with many notifications

---

## ✅ **Fix #5: Better Error Handling and Logging**

### **Problem**:
- Errors were logged but not handled gracefully
- No way to manually clear user ID cache
- Limited error context in logs

### **Solution**:
- Added static method to invalidate user ID cache
- Improved error messages with more context
- Better logging throughout the flow
- Graceful degradation on errors

### **Implementation**:
- **File**: `lib/services/notifications/leantime-adapter.ts`
- **Static Method**: `invalidateUserIdCache(email)`
- **Improved Logging**: More detailed error messages
- **Error Recovery**: Continues operation even if caching fails

### **Benefits**:
- ✅ Better debugging with detailed logs
- ✅ Manual cache clearing for troubleshooting
- ✅ More resilient to partial failures

---

## 📊 **Expected Behavior After Fixes**

### **Before Fixes**:
1. Mark all as read → `getLeantimeUserId()` fails → Returns `false`
2. Cache NOT invalidated → Count stays 65 ❌
3. User sees stale count

### **After Fixes**:
1. Mark all as read → `getLeantimeUserId()` checks cache first ✅
2. If cached: Uses cached ID immediately ✅
3. If not cached: Fetches with retry logic ✅
4. Marks notifications as read ✅
5. **Always invalidates cache** ✅
6. Count refresh gets fresh data → Shows 0 ✅

---

## 🎯 **Key Improvements**

### **Reliability**:
- ✅ User ID lookup is now cached and retried
- ✅ Cache always invalidated after marking
- ✅ Better error recovery

### **Performance**:
- ✅ Faster user ID lookup (cached)
- ✅ Reduced API calls to Leantime
- ✅ More efficient cache usage

### **Accuracy**:
- ✅ Count based on up to 1000 notifications
- ✅ Fresh data from API (bypasses stale cache)
- ✅ Better handling of edge cases

### **User Experience**:
- ✅ Count updates correctly after marking
- ✅ No more stuck count at 65
- ✅ Faster response times

---

## 🚀 **Testing Checklist**

After rebuild (`rm -rf .next && npm run build && npm start`):

1. ✅ **Test Mark All As Read**:
   - Should work even if user ID lookup was previously failing
   - Count should update to 0 after marking
   - Cache should be invalidated

2. ✅ **Test Mark Single As Read**:
   - Should work reliably
   - Count should decrement correctly
   - Cache should be invalidated

3. ✅ **Test Count Accuracy**:
   - Should show accurate count (up to 1000)
   - Should refresh after marking
   - Should use fresh data from API

4. ✅ **Test User ID Caching**:
   - First call should fetch from API
   - Subsequent calls should use cache
   - Should be faster on subsequent calls

5. ✅ **Test Retry Logic**:
   - Should retry on transient failures
   - Should eventually succeed or fail gracefully
   - Should log retry attempts

---

## 📝 **Files Modified**

1. **`lib/services/notifications/leantime-adapter.ts`**:
   - Added Redis caching for user ID
   - Added retry logic with exponential backoff
   - Improved `getNotificationCount()` to fetch directly from API
   - Added `invalidateUserIdCache()` static method
   - Better error handling and logging

2. **`lib/services/notifications/notification-service.ts`**:
   - Always invalidate cache in `markAsRead()`
   - Always invalidate cache in `markAllAsRead()`
   - Better error handling and logging

---

## 🔧 **Configuration**

- **User ID Cache TTL**: 3600 seconds (1 hour)
- **Max Retries**: 3 attempts
- **Retry Backoff**: Exponential (1s, 2s, 4s, max 5s)
- **Count Fetch Limit**: 1000 notifications

---

**Status**: ✅ All fixes implemented and ready for testing