fix(dm): prevent orphaned DMs on contact deletion, improve relinking

- Stop deleting contacts from DB on device removal (preserves DM history)
- Filter NULL contact_pubkey from DM conversations list
- Match outgoing DMs by contact name in raw_json during relinking

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/database.py

@@ -344,6 +344,7 @@ class Database:
                      ORDER BY d3.timestamp DESC LIMIT 1) AS last_direction
                 FROM direct_messages dm
                 LEFT JOIN contacts c ON dm.contact_pubkey = c.public_key
+                WHERE dm.contact_pubkey IS NOT NULL
                 GROUP BY dm.contact_pubkey
                 ORDER BY last_message_timestamp DESC"""
             ).fetchall()
@@ -382,22 +383,31 @@ class Database:
             ).fetchone()
             return dict(row) if row else None
 
-    def relink_orphaned_dms(self, public_key: str) -> int:
+    def relink_orphaned_dms(self, public_key: str, name: str = '') -> int:
         """Re-link DMs with NULL contact_pubkey back to this contact.
 
         When a contact is deleted, ON DELETE SET NULL nullifies contact_pubkey.
         When the contact is re-added, re-link those orphaned DMs.
-        Uses raw_json to match by pubkey_prefix.
+        Matches by pubkey prefix in raw_json (incoming) or contact name (outgoing).
         """
         public_key = public_key.lower()
-        prefix = public_key[:12]  # Short prefix used in pubkey_prefix field
+        prefix = public_key[:12]
         with self._connect() as conn:
-            cursor = conn.execute(
-                """UPDATE direct_messages SET contact_pubkey = ?
-                   WHERE contact_pubkey IS NULL
-                   AND (raw_json LIKE ? OR raw_json IS NULL)""",
-                (public_key, f'%{prefix}%')
-            )
+            if name:
+                cursor = conn.execute(
+                    """UPDATE direct_messages SET contact_pubkey = ?
+                       WHERE contact_pubkey IS NULL
+                       AND (raw_json LIKE ? OR raw_json LIKE ?
+                            OR raw_json IS NULL)""",
+                    (public_key, f'%{prefix}%', f'%"name": "{name}"%')
+                )
+            else:
+                cursor = conn.execute(
+                    """UPDATE direct_messages SET contact_pubkey = ?
+                       WHERE contact_pubkey IS NULL
+                       AND (raw_json LIKE ? OR raw_json IS NULL)""",
+                    (public_key, f'%{prefix}%')
+                )
             if cursor.rowcount > 0:
                 logger.info(f"Re-linked {cursor.rowcount} orphaned DMs to {public_key[:12]}...")
             return cursor.rowcount

app/device_manager.py

@@ -1000,13 +1000,14 @@ class DeviceManager:
             return self.db.get_contacts()  # return cached
 
     def delete_contact(self, pubkey: str) -> Dict:
-        """Delete a contact from device and database."""
+        """Delete a contact from device. Keep DB record to preserve DM history."""
         if not self.is_connected:
             return {'success': False, 'error': 'Device not connected'}
 
         try:
             self.execute(self.mc.commands.remove_contact(pubkey))
-            self.db.delete_contact(pubkey)
+            # Don't delete from DB — ON DELETE SET NULL would orphan all DMs.
+            # Contact stays in DB for historical reference; upsert updates on re-add.
             # Also remove from in-memory contacts cache
             if self.mc.contacts and pubkey in self.mc.contacts:
                 del self.mc.contacts[pubkey]
@@ -1187,7 +1188,8 @@ class DeviceManager:
                 source='device',
             )
             # Re-link orphaned DMs (from previous ON DELETE SET NULL)
-            self.db.relink_orphaned_dms(pubkey)
+            contact_name = contact.get('adv_name', contact.get('name', ''))
+            self.db.relink_orphaned_dms(pubkey, name=contact_name)
 
             # Remove from pending list after successful approval
             self.mc.pending_contacts.pop(pubkey, None)