fix(session): normalize CreatedAt in SessionManager AddFullMessage/SetHistory

pkg/agent/turn_profile_test.go

@@ -105,9 +105,10 @@ func TestTurnProfile_DisabledPreservesDefaultHistoryAndPrompt(t *testing.T) {
 	al := newTurnProfileAgentLoop(t, cfg, provider)
 	agent := al.GetRegistry().GetDefaultAgent()
 	sessionKey := "agent:default:test-default"
+	ts := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
 	initialHistory := []providers.Message{
-		{Role: "user", Content: "old user"},
-		{Role: "assistant", Content: "old assistant"},
+		{Role: "user", Content: "old user", CreatedAt: &ts},
+		{Role: "assistant", Content: "old assistant", CreatedAt: &ts},
 	}
 	agent.Sessions.SetHistory(sessionKey, initialHistory)
 	agent.Sessions.SetSummary(sessionKey, "old summary")
@@ -154,9 +155,10 @@ func TestTurnProfile_HistoryOffSuppressesHistoryAndPersistence(t *testing.T) {
 	al := newTurnProfileAgentLoop(t, cfg, provider)
 	agent := al.GetRegistry().GetDefaultAgent()
 	sessionKey := "agent:default:test-history-off"
+	ts := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
 	initialHistory := []providers.Message{
-		{Role: "user", Content: "old user"},
-		{Role: "assistant", Content: "old assistant"},
+		{Role: "user", Content: "old user", CreatedAt: &ts},
+		{Role: "assistant", Content: "old assistant", CreatedAt: &ts},
 	}
 	agent.Sessions.SetHistory(sessionKey, initialHistory)
 	agent.Sessions.SetSummary(sessionKey, "old summary")

pkg/session/manager.go

@@ -87,8 +87,13 @@ func (sm *SessionManager) AddFullMessage(sessionKey string, msg providers.Messag
 		sm.sessions[sessionKey] = session
 	}
 
+	now := time.Now()
+	if msg.CreatedAt == nil {
+		msg.CreatedAt = &now
+	}
+
 	session.Messages = append(session.Messages, msg)
-	session.Updated = time.Now()
+	session.Updated = now
 }
 
 func (sm *SessionManager) GetHistory(key string) []providers.Message {
@@ -300,7 +305,13 @@ func (sm *SessionManager) SetHistory(key string, history []providers.Message) {
 		// from the caller's slice.
 		msgs := make([]providers.Message, len(history))
 		copy(msgs, history)
+		now := time.Now()
+		for i := range msgs {
+			if msgs[i].CreatedAt == nil {
+				msgs[i].CreatedAt = &now
+			}
+		}
 		session.Messages = msgs
-		session.Updated = time.Now()
+		session.Updated = now
 	}
 }

web/backend/api/session.go

@@ -732,7 +732,11 @@ func visibleAssistantToolArgsPreview(
 	return utils.VisibleToolCallArgumentsPreview(tc, toolFeedbackMaxArgsLength)
 }
 
-func visibleAssistantToolMessages(toolCalls []providers.ToolCall, modelName string, createdAt *time.Time) []sessionChatMessage {
+func visibleAssistantToolMessages(
+	toolCalls []providers.ToolCall,
+	modelName string,
+	createdAt *time.Time,
+) []sessionChatMessage {
 	if len(toolCalls) == 0 {
 		return nil
 	}