fix(feishu): early-return for non-reply messages, add cache and fetchMessageByID comment

pkg/channels/feishu/feishu_64.go

@@ -469,6 +469,13 @@ func (c *FeishuChannel) handleMessageReceive(ctx context.Context, event *larkim.
 		content = "[empty message]"
 	}
 
+	if replyTargetID(message) != "" || stringValue(message.ThreadId) != "" {
+		content, mediaRefs = c.prependReplyContext(ctx, message, chatID, content, mediaRefs)
+	}
+	if content == "" {
+		content = "[empty message]"
+	}
+
 	logger.InfoCF("feishu", "Feishu message received", map[string]any{
 		"sender_id":  senderID,
 		"chat_id":    chatID,

pkg/channels/feishu/feishu_reply.go

@@ -147,7 +147,8 @@ func (c *FeishuChannel) fetchMessageByID(ctx context.Context, messageID string)
 	if resp.Data == nil || len(resp.Data.Items) == 0 || resp.Data.Items[0] == nil {
 		return nil, fmt.Errorf("feishu get message: empty response")
 	}
-
+	// Items[0] contains the target message - the Feishu API returns a list
+	// but we request a single message by ID, so the list always has at most one item.
 	msg := resp.Data.Items[0]
 	c.messageCache.Store(messageID, &cachedMessage{msg: msg, expiry: time.Now().Add(messageCacheTTL)})
 	return msg, nil