merge upstream and keep full message timestamps

pkg/memory/jsonl.go

@@ -524,6 +524,7 @@ func (s *JSONLStore) AddMessage(
 	return s.addMsg(sessionKey, providers.Message{
 		Role:      role,
 		Content:   content,
+		Timestamp: time.Now().Format(time.RFC3339Nano),
 	})
 }
 
@@ -539,6 +540,10 @@ func (s *JSONLStore) addMsg(sessionKey string, msg providers.Message) error {
 	l.Lock()
 	defer l.Unlock()
 
+	if strings.TrimSpace(msg.Timestamp) == "" {
+		msg.Timestamp = time.Now().Format(time.RFC3339Nano)
+	}
+
 	// Append the message as a single JSON line.
 	line, err := json.Marshal(msg)
 	if err != nil {

pkg/memory/jsonl_test.go

@@ -61,9 +61,15 @@ func TestAddMessage_BasicRoundtrip(t *testing.T) {
 	if history[0].Role != "user" || history[0].Content != "hello" {
 		t.Errorf("msg[0] = %+v", history[0])
 	}
+	if history[0].Timestamp == "" {
+		t.Errorf("msg[0].Timestamp is empty")
+	}
 	if history[1].Role != "assistant" || history[1].Content != "hi there" {
 		t.Errorf("msg[1] = %+v", history[1])
 	}
+	if history[1].Timestamp == "" {
+		t.Errorf("msg[1].Timestamp is empty")
+	}
 }
 
 func TestAddMessage_AutoCreatesSession(t *testing.T) {

pkg/providers/protocoltypes/types.go

@@ -74,6 +74,7 @@ type Attachment struct {
 type Message struct {
 	Role             string         `json:"role"`
 	Content          string         `json:"content"`
+	Timestamp        string         `json:"timestamp,omitempty"`
 	Media            []string       `json:"media,omitempty"`
 	Attachments      []Attachment   `json:"attachments,omitempty"`
 	ReasoningContent string         `json:"reasoning_content,omitempty"`

pkg/session/manager.go

@@ -72,6 +72,10 @@ func (sm *SessionManager) AddFullMessage(sessionKey string, msg providers.Messag
 	sm.mu.Lock()
 	defer sm.mu.Unlock()
 
+	if strings.TrimSpace(msg.Timestamp) == "" {
+		msg.Timestamp = time.Now().Format(time.RFC3339Nano)
+	}
+
 	session, ok := sm.sessions[sessionKey]
 	if !ok {
 		session = &Session{

web/backend/api/session.go

@@ -48,6 +48,7 @@ type sessionListItem struct {
 type sessionChatMessage struct {
 	Role        string                  `json:"role"`
 	Content     string                  `json:"content"`
+	Timestamp   string                  `json:"timestamp,omitempty"`
 	Media       []string                `json:"media,omitempty"`
 	Attachments []sessionChatAttachment `json:"attachments,omitempty"`
 }
@@ -477,6 +478,7 @@ func visibleSessionMessages(messages []providers.Message, toolFeedbackMaxArgsLen
 
 	for _, msg := range messages {
 		attachments := sessionAttachments(msg)
+		timestamp := strings.TrimSpace(msg.Timestamp)
 
 		switch msg.Role {
 		case "tool":
@@ -486,6 +488,7 @@ func visibleSessionMessages(messages []providers.Message, toolFeedbackMaxArgsLen
 			chatMsg := sessionChatMessage{
 				Role:        "user",
 				Content:     msg.Content,
+				Timestamp:   timestamp,
 				Media:       append([]string(nil), msg.Media...),
 				Attachments: attachments,
 			}
@@ -500,12 +503,12 @@ func visibleSessionMessages(messages []providers.Message, toolFeedbackMaxArgsLen
 				continue
 			}
 
-			toolSummaryMessages := visibleAssistantToolSummaryMessages(msg.ToolCalls, toolFeedbackMaxArgsLength)
+			toolSummaryMessages := visibleAssistantToolSummaryMessages(msg.ToolCalls, timestamp, toolFeedbackMaxArgsLength)
 			if len(toolSummaryMessages) > 0 {
 				transcript = append(transcript, toolSummaryMessages...)
 			}
 
-			visibleToolMessages := visibleAssistantToolMessages(msg.ToolCalls)
+			visibleToolMessages := visibleAssistantToolMessages(msg.ToolCalls, timestamp)
 			if len(visibleToolMessages) > 0 {
 				transcript = append(transcript, visibleToolMessages...)
 			}
@@ -534,6 +537,7 @@ func visibleSessionMessages(messages []providers.Message, toolFeedbackMaxArgsLen
 			chatMsg := sessionChatMessage{
 				Role:        "assistant",
 				Content:     content,
+				Timestamp:   timestamp,
 				Media:       append([]string(nil), msg.Media...),
 				Attachments: attachments,
 			}
@@ -686,6 +690,7 @@ func assistantMessageInternalOnly(msg providers.Message) bool {
 
 func visibleAssistantToolSummaryMessages(
 	toolCalls []providers.ToolCall,
+	timestamp string,
 	toolFeedbackMaxArgsLength int,
 ) []sessionChatMessage {
 	if len(toolCalls) == 0 {
@@ -716,6 +721,7 @@ func visibleAssistantToolSummaryMessages(
 				name,
 				visibleAssistantToolSummaryText(tc, toolFeedbackMaxArgsLength),
 			),
+			Timestamp: timestamp,
 		})
 	}
 
@@ -745,7 +751,7 @@ func visibleAssistantToolSummaryText(
 	return utils.Truncate(strings.TrimSpace(argsJSON), toolFeedbackMaxArgsLength)
 }
 
-func visibleAssistantToolMessages(toolCalls []providers.ToolCall) []sessionChatMessage {
+func visibleAssistantToolMessages(toolCalls []providers.ToolCall, timestamp string) []sessionChatMessage {
 	if len(toolCalls) == 0 {
 		return nil
 	}
@@ -763,6 +769,7 @@ func visibleAssistantToolMessages(toolCalls []providers.ToolCall) []sessionChatM
 		messages = append(messages, sessionChatMessage{
 			Role:      "assistant",
 			Content:   content,
+			Timestamp: timestamp,
 		})
 	}
 

web/backend/api/session_test.go

@@ -166,8 +166,8 @@ func TestHandleGetSession_JSONLStorage(t *testing.T) {
 
 	sessionKey := legacyPicoSessionPrefix + "detail-jsonl"
 	for _, msg := range []providers.Message{
-		{Role: "user", Content: "first"},
+		{Role: "user", Content: "first", Timestamp: "2026-04-23T11:05:00+08:00"},
-		{Role: "assistant", Content: "second"},
+		{Role: "assistant", Content: "second", Timestamp: "2026-04-23T11:06:00+08:00"},
 		{Role: "tool", Content: "ignored"},
 	} {
 		if err := store.AddFullMessage(nil, sessionKey, msg); err != nil {
@@ -196,6 +196,7 @@ func TestHandleGetSession_JSONLStorage(t *testing.T) {
 		Messages []struct {
 			Role      string `json:"role"`
 			Content   string `json:"content"`
+			Timestamp string `json:"timestamp"`
 		} `json:"messages"`
 	}
 	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
@@ -213,9 +214,15 @@ func TestHandleGetSession_JSONLStorage(t *testing.T) {
 	if resp.Messages[0].Role != "user" || resp.Messages[0].Content != "first" {
 		t.Fatalf("first message = %#v, want user/first", resp.Messages[0])
 	}
+	if resp.Messages[0].Timestamp != "2026-04-23T11:05:00+08:00" {
+		t.Fatalf("resp.Messages[0].Timestamp = %q, want %q", resp.Messages[0].Timestamp, "2026-04-23T11:05:00+08:00")
+	}
 	if resp.Messages[1].Role != "assistant" || resp.Messages[1].Content != "second" {
 		t.Fatalf("second message = %#v, want assistant/second", resp.Messages[1])
 	}
+	if resp.Messages[1].Timestamp != "2026-04-23T11:06:00+08:00" {
+		t.Fatalf("resp.Messages[1].Timestamp = %q, want %q", resp.Messages[1].Timestamp, "2026-04-23T11:06:00+08:00")
+	}
 }
 
 func TestHandleGetSession_HidesHandledToolAttachmentsBackedByMediaRefs(t *testing.T) {

web/frontend/src/api/sessions.ts

@@ -14,6 +14,7 @@ export interface SessionDetail {
   messages: {
     role: "user" | "assistant"
     content: string
+    timestamp?: string
     media?: string[]
     attachments?: {
       type?: "image" | "audio" | "video" | "file"

web/frontend/src/features/chat/history.ts

@@ -50,7 +50,7 @@ export async function loadSessionMessages(
       media: message.media,
       attachments: message.attachments,
     }),
-    timestamp: fallbackTime,
+    timestamp: message.timestamp?.trim() || fallbackTime,
   }))
 }
 

web/frontend/src/hooks/use-pico-chat.ts

@@ -38,20 +38,7 @@ export function formatMessageTime(dateRaw: number | string | Date): string {
   if (!date.isValid()) {
     return ""
   }
-  const now = dayjs()
+  return date.format("YYYY-MM-DD HH:mm")
-
-  const isToday = date.isSame(now, "day")
-  const isThisYear = date.isSame(now, "year")
-
-  if (isToday) {
-    return date.format("LT")
-  }
-
-  if (isThisYear) {
-    return date.format("MMM D LT")
-  }
-
-  return date.format("ll LT")
 }
 
 export function usePicoChat() {