oAI/Services/ConversationMergeService.swift

@@ -67,6 +67,14 @@ enum ConversationMergeService {
             try DatabaseService.shared.loadConversation(id: id)
         }
 
+        // The model used in the merged conversation should reflect the most recently used
+        // model across the *source* conversations — never the model that performed the merge.
+        let latestModelId = sources
+            .flatMap { $0.1 }
+            .filter { $0.modelId != nil }
+            .max { $0.timestamp < $1.timestamp }?
+            .modelId
+
         let mergedMessages: [Message]
         switch mode {
         case .simple:
@@ -75,7 +83,12 @@ enum ConversationMergeService {
             mergedMessages = try await aiMerge(sources)
         }
 
-        let newConversation = try DatabaseService.shared.saveConversation(name: name, messages: mergedMessages)
+        let newConversation = try DatabaseService.shared.saveConversation(
+            id: UUID(),
+            name: name,
+            messages: mergedMessages,
+            primaryModel: latestModelId
+        )
 
         if deleteOriginals {
             for id in conversationIds {
@@ -148,13 +161,15 @@ enum ConversationMergeService {
 
         let turns = try parseTurns(from: response.content)
 
+        // modelId intentionally left nil here: these messages are a synthesized composite,
+        // not output from a single source model. The conversation's primaryModel (set by the
+        // caller from the source conversations) is what drives the model shown in the list.
         let base = Date()
         return turns.enumerated().map { index, turn in
             Message(
                 role: turn.role == "user" ? .user : .assistant,
                 content: turn.content,
-                timestamp: base.addingTimeInterval(TimeInterval(index)),
-                modelId: modelId
+                timestamp: base.addingTimeInterval(TimeInterval(index))
             )
         }
     }