CRITICAL: Fix database upsert bug preventing manual scan date persistence

**Root Cause**: upsert_movie_dates() was UPDATE-only, not proper upsert
- Manual scans failed to save dateadded to database (NULL values)
- Webhooks found database entries but with NULL dateadded
- Fell back to current timestamp instead of using proper import dates

**Database Fix**:
- Changed core/database.py upsert_movie_dates() from UPDATE to INSERT OR REPLACE
- Now properly saves dateadded during manual scans
- Preserves existing path with COALESCE fallback

**Webhook Enhancement**:
- Added comprehensive debug logging for database lookups
- Enhanced webhook date decision logic with proper fallback chain
- Only uses current timestamp as absolute last resort

**Impact**:
- Movies: Manual scans now persist dates, webhooks find existing entries ✅
- TV Shows: Not affected - already using proper INSERT OR REPLACE ✅
- Version: 1.5.5

SUMMARY.md

@@ -1,8 +1,21 @@
 # NFOGuard Development Summary
 
-## Current Status: v1.5.3 - Radarr Rename Event Fix! 🔧
+## Current Status: v1.5.5 - Database Upsert Fix! 🔧
 
-### Latest Updates (v1.5.3) - September 15, 2025
+### Latest Updates (v1.5.5) - September 15, 2025
+- **🔧 DATABASE BUG FIX**: Fixed `upsert_movie_dates` to be a proper upsert operation
+- **💾 DATA INTEGRITY**: Manual scans now properly save `dateadded` to database  
+- **🎯 ROOT CAUSE**: Fixed UPDATE-only operation that was leaving `dateadded` fields NULL
+- **✅ WEBHOOK FIX**: Webhooks now find existing database entries correctly
+- **📺 TV SHOWS**: NOT affected - already using proper `INSERT OR REPLACE` operations
+
+### Previous Updates (v1.5.4) - September 15, 2025
+- **🎯 WEBHOOK DATE FIX**: Fixed webhook processing to use proper date decision logic
+- **🔍 SMART FALLBACK**: Webhooks now check database → Radarr import dates → release dates → timestamp
+- **❌ ISSUE RESOLVED**: Upgrade webhooks no longer incorrectly use current timestamp when database exists
+- **✅ PROPER FLOW**: Webhook mode now uses same date logic as manual scans for missing entries
+
+### Previous Updates (v1.5.3) - September 15, 2025
 - **🔧 RADARR RENAME FIX**: Added missing event type filtering to Radarr webhooks
 - **✅ CONSISTENCY**: Radarr now matches Sonarr's event handling (Download, Upgrade, Rename)
 - **🎯 FIXED ISSUE**: Radarr rename events now properly trigger NFO updates with correct dates
@@ -63,6 +76,63 @@ SUPPRESS_TVDB_WARNINGS=true   # Hide non-critical TVDB failures
 
 ---
 
+## 🔧 FIXED: Database Upsert Bug (September 15, 2025) - **CRITICAL**
+
+### Issue Discovery
+**The Real Root Cause**: Manual scans were NOT actually saving `dateadded` to database due to faulty upsert operation!
+
+### Problem Details
+**Database Method Bug** in `core/database.py:173-182`:
+- `upsert_movie_dates()` was doing UPDATE-only, not proper upsert
+- If movie row didn't exist properly, UPDATE would affect 0 rows  
+- `dateadded` field remained NULL even after manual scan
+- Webhooks found database entries but with NULL `dateadded` → fell back to current timestamp
+
+### 🔧 **Fix Applied**
+- **Location**: `core/database.py:173-186`
+- **Changed**: UPDATE-only → proper `INSERT OR REPLACE` upsert
+- **Result**: Manual scans now properly save `dateadded` to database
+- **Webhook Impact**: Now finds existing dates correctly, no more false timestamps
+
+### Before vs After Database Operations
+**Before (BROKEN):**
+```sql
+UPDATE movies SET dateadded = '2025-06-15...' WHERE imdb_id = 'tt123';
+-- If row doesn't exist properly: 0 rows affected, dateadded stays NULL
+```
+
+**After (FIXED):**
+```sql
+INSERT OR REPLACE INTO movies (...) VALUES (...);
+-- Always works: Creates row OR replaces with all data including dateadded
+```
+
+---
+
+## 🎯 FIXED: Webhook Date Logic Issue (September 15, 2025)
+
+### Issue Discovery  
+Upgrade webhooks were incorrectly using current timestamp (`webhook:first_seen`) instead of checking Radarr for proper import dates when no database entry existed.
+
+**Example Problem:**
+- Database populated via manual scan: `2025-06-15T11:10:31-04:00` (radarr:db.history.import)
+- Upgrade webhook comes in: `2025-09-15T12:04:23-04:00` (webhook:first_seen) ❌ **WRONG!**
+
+### Root Cause
+Webhook mode was bypassing the full date decision logic (`_decide_movie_dates`) and jumping straight to current timestamp as fallback.
+
+### ✅ **Fix Applied**
+- **Location**: `nfoguard.py:975-990`
+- **Logic**: Webhook mode now uses same date priority as manual scans:
+  1. **Database first** (if exists)
+  2. **Full date logic** (Radarr import → release dates → fallbacks)  
+  3. **Current timestamp** (only as absolute last resort)
+
+### Result
+Webhook upgrades now properly find and use existing Radarr import dates instead of creating false "first seen" timestamps.
+
+---
+
 ## 🔧 FIXED: Radarr Rename Event Issue (September 15, 2025)
 
 ### Issue Resolution