Fix PHONE.csv import duplicate constraint error

- Implement upsert logic in import_phone() function
- Check for existing (id, phone) combinations before insert
- Track duplicates within CSV to skip gracefully
- Update existing records instead of failing on duplicates
- Add detailed statistics: inserted, updated, skipped counts
- Align with upsert pattern used in other import functions
- Add documentation in docs/PHONE_IMPORT_FIX.md

Fixes: UNIQUE constraint failed: phone.id, phone.phone error
when re-importing or uploading CSV with duplicate entries

app/import_legacy.py

@@ -772,14 +772,16 @@ def import_rolodex(db: Session, file_path: str) -> Dict[str, Any]:
 
 
 def import_phone(db: Session, file_path: str) -> Dict[str, Any]:
-    """Import PHONE.csv → LegacyPhone model."""
-    result = {'success': 0, 'errors': [], 'total_rows': 0}
+    """Import PHONE.csv → LegacyPhone model with upsert logic."""
+    result = {'success': 0, 'errors': [], 'total_rows': 0, 'updated': 0, 'inserted': 0, 'skipped': 0}
     
     try:
         f, encoding = open_text_with_fallbacks(file_path)
         reader = csv.DictReader(f)
         
-        batch = []
+        # Track seen combinations in this import to handle duplicates within the CSV
+        seen_in_import = set()
+        
         for row_num, row in enumerate(reader, start=2):
             result['total_rows'] += 1
             
@@ -790,26 +792,48 @@ def import_phone(db: Session, file_path: str) -> Dict[str, Any]:
                 if not rolodex_id or not phone:
                     continue
                 
-                record = LegacyPhone(
-                    id=rolodex_id,
-                    phone=phone,
-                    location=clean_string(row.get('Location'))
-                )
-                batch.append(record)
+                # Create a composite key for tracking
+                composite_key = (rolodex_id, phone)
                 
-                if len(batch) >= BATCH_SIZE:
-                    db.bulk_save_objects(batch)
+                # Skip if we've already processed this combination in current import
+                if composite_key in seen_in_import:
+                    result['skipped'] += 1
+                    continue
+                
+                seen_in_import.add(composite_key)
+                
+                # Check if record already exists in database
+                existing = db.query(LegacyPhone).filter(
+                    LegacyPhone.id == rolodex_id,
+                    LegacyPhone.phone == phone
+                ).first()
+                
+                if existing:
+                    # Update existing record
+                    existing.location = clean_string(row.get('Location'))
+                    result['updated'] += 1
+                else:
+                    # Insert new record
+                    record = LegacyPhone(
+                        id=rolodex_id,
+                        phone=phone,
+                        location=clean_string(row.get('Location'))
+                    )
+                    db.add(record)
+                    result['inserted'] += 1
+                
+                result['success'] += 1
+                
+                # Commit in batches for performance
+                if result['success'] % BATCH_SIZE == 0:
                     db.commit()
-                    result['success'] += len(batch)
-                    batch = []
                     
             except Exception as e:
                 result['errors'].append(f"Row {row_num}: {str(e)}")
+                db.rollback()
         
-        if batch:
-            db.bulk_save_objects(batch)
-            db.commit()
-            result['success'] += len(batch)
+        # Commit any remaining changes
+        db.commit()
         
         f.close()
         logger.info("import_phone_complete", **result)