feat(channels): auto-orchestrate Placeholder/Typing/Reaction via capability interfaces

Define PlaceholderCapable, TypingCapable, and ReactionCapable interfaces
and have BaseChannel.HandleMessage auto-detect and trigger all three as
independent pipelines on inbound messages. This replaces the scattered
manual orchestration code in each channel's handleMessage with a single
unified dispatch in the framework layer.

Changes:
- Add PlaceholderCapable interface to interfaces.go
- Add ReactionCapable + RecordReactionUndo to interfaces.go
- BaseChannel.HandleMessage auto-triggers Typing → Reaction → Placeholder
- Manager gains reactionUndos sync.Map with TTL janitor cleanup
- Telegram: extract SendPlaceholder from manual code, add StartTyping
- Discord: add SendPlaceholder + StartTyping
- Pico: add SendPlaceholder (uses Pico Protocol message.create)
- Slack: extract ReactToMessage from manual code
- OneBot: extract ReactToMessage, remove leaked pendingEmojiMsg sync.Map
- LINE: move group-chat guard into StartTyping, remove manual orchestration
- Config: add Placeholder to PicoConfig; remove from Slack/LINE/OneBot
  (no MessageEditor, so placeholder config was dead code)

pkg/channels/base.go

@@ -82,6 +82,7 @@ type BaseChannel struct {
 	groupTrigger        config.GroupTriggerConfig
 	mediaStore          media.MediaStore
 	placeholderRecorder PlaceholderRecorder
+	owner               Channel // the concrete channel that embeds this BaseChannel
 }
 
 func NewBaseChannel(
@@ -257,6 +258,29 @@ func (c *BaseChannel) HandleMessage(
 		Metadata:   metadata,
 	}
 
+	// Auto-trigger typing indicator, message reaction, and placeholder before publishing.
+	// Each capability is independent — all three may fire for the same message.
+	if c.owner != nil && c.placeholderRecorder != nil {
+		// Typing — independent pipeline
+		if tc, ok := c.owner.(TypingCapable); ok {
+			if stop, err := tc.StartTyping(ctx, chatID); err == nil {
+				c.placeholderRecorder.RecordTypingStop(c.name, chatID, stop)
+			}
+		}
+		// Reaction — independent pipeline
+		if rc, ok := c.owner.(ReactionCapable); ok && messageID != "" {
+			if undo, err := rc.ReactToMessage(ctx, chatID, messageID); err == nil {
+				c.placeholderRecorder.RecordReactionUndo(c.name, chatID, undo)
+			}
+		}
+		// Placeholder — independent pipeline
+		if pc, ok := c.owner.(PlaceholderCapable); ok {
+			if phID, err := pc.SendPlaceholder(ctx, chatID); err == nil && phID != "" {
+				c.placeholderRecorder.RecordPlaceholder(c.name, chatID, phID)
+			}
+		}
+	}
+
 	if err := c.bus.PublishInbound(ctx, msg); err != nil {
 		logger.ErrorCF("channels", "Failed to publish inbound message", map[string]any{
 			"channel": c.name,
@@ -286,6 +310,12 @@ func (c *BaseChannel) GetPlaceholderRecorder() PlaceholderRecorder {
 	return c.placeholderRecorder
 }
 
+// SetOwner injects the concrete channel that embeds this BaseChannel.
+// This allows HandleMessage to auto-trigger TypingCapable / ReactionCapable / PlaceholderCapable.
+func (c *BaseChannel) SetOwner(ch Channel) {
+	c.owner = ch
+}
+
 // BuildMediaScope constructs a scope key for media lifecycle tracking.
 func BuildMediaScope(channel, chatID, messageID string) string {
 	id := messageID

pkg/channels/discord/discord.go

@@ -224,6 +224,27 @@ func (c *DiscordChannel) EditMessage(ctx context.Context, chatID string, message
 	return err
 }
 
+// SendPlaceholder implements channels.PlaceholderCapable.
+// It sends a placeholder message that will later be edited to the actual
+// response via EditMessage (channels.MessageEditor).
+func (c *DiscordChannel) SendPlaceholder(ctx context.Context, chatID string) (string, error) {
+	if !c.config.Placeholder.Enabled {
+		return "", nil
+	}
+
+	text := c.config.Placeholder.Text
+	if text == "" {
+		text = "Thinking... 💭"
+	}
+
+	msg, err := c.session.ChannelMessageSend(chatID, text)
+	if err != nil {
+		return "", err
+	}
+
+	return msg.ID, nil
+}
+
 func (c *DiscordChannel) sendChunk(ctx context.Context, channelID, content string) error {
 	// Use the passed ctx for timeout control
 	sendCtx, cancel := context.WithTimeout(ctx, sendTimeout)
@@ -360,13 +381,6 @@ func (c *DiscordChannel) handleMessage(s *discordgo.Session, m *discordgo.Messag
 		content = "[media only]"
 	}
 
-	// Start typing after all early returns — guaranteed to have a matching Send()
-	c.startTyping(m.ChannelID)
-	// Register typing stop with Manager for outbound orchestration
-	if rec := c.GetPlaceholderRecorder(); rec != nil {
-		rec.RecordTypingStop("discord", m.ChannelID, func() { c.stopTyping(m.ChannelID) })
-	}
-
 	logger.DebugCF("discord", "Received message", map[string]any{
 		"sender_name": sender.DisplayName,
 		"sender_id":   senderID,
@@ -440,6 +454,13 @@ func (c *DiscordChannel) stopTyping(chatID string) {
 	}
 }
 
+// StartTyping implements channels.TypingCapable.
+// It starts a continuous typing indicator and returns an idempotent stop function.
+func (c *DiscordChannel) StartTyping(ctx context.Context, chatID string) (func(), error) {
+	c.startTyping(chatID)
+	return func() { c.stopTyping(chatID) }, nil
+}
+
 func (c *DiscordChannel) downloadAttachment(url, filename string) string {
 	return utils.DownloadFile(url, filename, utils.DownloadOptions{
 		LoggerPrefix: "discord",

pkg/channels/interfaces.go

@@ -15,10 +15,27 @@ type MessageEditor interface {
 	EditMessage(ctx context.Context, chatID string, messageID string, content string) error
 }
 
+// ReactionCapable — channels that can add a reaction (e.g. 👀) to an inbound message.
+// ReactToMessage adds a reaction and returns an undo function to remove it.
+// The undo function MUST be idempotent and safe to call multiple times.
+type ReactionCapable interface {
+	ReactToMessage(ctx context.Context, chatID, messageID string) (undo func(), err error)
+}
+
+// PlaceholderCapable — channels that can send a placeholder message
+// (e.g. "Thinking... 💭") that will later be edited to the actual response.
+// The channel MUST also implement MessageEditor for the placeholder to be useful.
+// SendPlaceholder returns the platform message ID of the placeholder so that
+// Manager.preSend can later edit it via MessageEditor.EditMessage.
+type PlaceholderCapable interface {
+	SendPlaceholder(ctx context.Context, chatID string) (messageID string, err error)
+}
+
 // PlaceholderRecorder is injected into channels by Manager.
 // Channels call these methods on inbound to register typing/placeholder state.
 // Manager uses the registered state on outbound to stop typing and edit placeholders.
 type PlaceholderRecorder interface {
 	RecordPlaceholder(channel, chatID, placeholderID string)
 	RecordTypingStop(channel, chatID string, stop func())
+	RecordReactionUndo(channel, chatID string, undo func())
 }

pkg/channels/line/line.go

@@ -378,28 +378,6 @@ func (c *LINEChannel) processEvent(event lineEvent) {
 		return
 	}
 
-	// Thinking indicator (LINE loading animation is 1:1 only).
-	// For group/room chats, LINE provides no equivalent API.
-	// Only start if PlaceholderRecorder is available to avoid wasted API calls.
-	if !isGroup {
-		if rec := c.GetPlaceholderRecorder(); rec != nil {
-			typingCtx, typingCancel := context.WithTimeout(c.ctx, 5*time.Minute)
-			stop, err := c.StartTyping(typingCtx, chatID)
-			if err == nil {
-				var stopOnce sync.Once
-				stopFn := func() {
-					stopOnce.Do(func() {
-						stop()
-						typingCancel()
-					})
-				}
-				rec.RecordTypingStop("line", chatID, stopFn)
-			} else {
-				typingCancel()
-			}
-		}
-	}
-
 	c.HandleMessage(c.ctx, peer, msg.ID, senderID, chatID, content, mediaPaths, metadata, sender)
 }
 
@@ -598,15 +576,19 @@ func (c *LINEChannel) sendPush(ctx context.Context, to, content, quoteToken stri
 
 // StartTyping implements channels.TypingCapable using LINE's loading animation.
 //
-// NOTE: The LINE loading animation API only works for 1:1 chats. Callers must ensure
-// the provided chatID is a user chat ID (not a group/room ID).
-// There is no explicit "stop" API; we periodically re-send start requests to keep
-// the indicator alive, and stop by canceling the context.
+// NOTE: The LINE loading animation API only works for 1:1 chats.
+// Group/room chat IDs (starting with "C" or "R") are detected automatically;
+// for these, a no-op stop function is returned without calling the API.
 func (c *LINEChannel) StartTyping(ctx context.Context, chatID string) (func(), error) {
 	if chatID == "" {
 		return func() {}, nil
 	}
 
+	// Group/room chats: LINE loading animation is 1:1 only.
+	if strings.HasPrefix(chatID, "C") || strings.HasPrefix(chatID, "R") {
+		return func() {}, nil
+	}
+
 	typingCtx, cancel := context.WithCancel(ctx)
 	var once sync.Once
 	stop := func() { once.Do(cancel) }

pkg/channels/manager.go

@@ -44,6 +44,12 @@ type typingEntry struct {
 	createdAt time.Time
 }
 
+// reactionEntry wraps a reaction undo function with a creation timestamp for TTL eviction.
+type reactionEntry struct {
+	undo      func()
+	createdAt time.Time
+}
+
 // placeholderEntry wraps a placeholder ID with a creation timestamp for TTL eviction.
 type placeholderEntry struct {
 	id        string
@@ -68,17 +74,18 @@ type channelWorker struct {
 }
 
 type Manager struct {
-	channels     map[string]Channel
-	workers      map[string]*channelWorker
-	bus          *bus.MessageBus
-	config       *config.Config
-	mediaStore   media.MediaStore
-	dispatchTask *asyncTask
-	mux          *http.ServeMux
-	httpServer   *http.Server
-	mu           sync.RWMutex
-	placeholders sync.Map // "channel:chatID" → placeholderID (string)
-	typingStops  sync.Map // "channel:chatID" → func()
+	channels      map[string]Channel
+	workers       map[string]*channelWorker
+	bus           *bus.MessageBus
+	config        *config.Config
+	mediaStore    media.MediaStore
+	dispatchTask  *asyncTask
+	mux           *http.ServeMux
+	httpServer    *http.Server
+	mu            sync.RWMutex
+	placeholders  sync.Map // "channel:chatID" → placeholderID (string)
+	typingStops   sync.Map // "channel:chatID" → func()
+	reactionUndos sync.Map // "channel:chatID" → reactionEntry
 }
 
 type asyncTask struct {
@@ -99,7 +106,14 @@ func (m *Manager) RecordTypingStop(channel, chatID string, stop func()) {
 	m.typingStops.Store(key, typingEntry{stop: stop, createdAt: time.Now()})
 }
 
-// preSend handles typing stop and placeholder editing before sending a message.
+// RecordReactionUndo registers a reaction undo function for later invocation.
+// Implements PlaceholderRecorder.
+func (m *Manager) RecordReactionUndo(channel, chatID string, undo func()) {
+	key := channel + ":" + chatID
+	m.reactionUndos.Store(key, reactionEntry{undo: undo, createdAt: time.Now()})
+}
+
+// preSend handles typing stop, reaction undo, and placeholder editing before sending a message.
 // Returns true if the message was edited into a placeholder (skip Send).
 func (m *Manager) preSend(ctx context.Context, name string, msg bus.OutboundMessage, ch Channel) bool {
 	key := name + ":" + msg.ChatID
@@ -111,7 +125,14 @@ func (m *Manager) preSend(ctx context.Context, name string, msg bus.OutboundMess
 		}
 	}
 
-	// 2. Try editing placeholder
+	// 2. Undo reaction
+	if v, loaded := m.reactionUndos.LoadAndDelete(key); loaded {
+		if entry, ok := v.(reactionEntry); ok {
+			entry.undo() // idempotent, safe
+		}
+	}
+
+	// 3. Try editing placeholder
 	if v, loaded := m.placeholders.LoadAndDelete(key); loaded {
 		if entry, ok := v.(placeholderEntry); ok && entry.id != "" {
 			if editor, ok := ch.(MessageEditor); ok {
@@ -171,6 +192,10 @@ func (m *Manager) initChannel(name, displayName string) {
 		if setter, ok := ch.(interface{ SetPlaceholderRecorder(r PlaceholderRecorder) }); ok {
 			setter.SetPlaceholderRecorder(m)
 		}
+		// Inject owner reference so BaseChannel.HandleMessage can auto-trigger typing/reaction
+		if setter, ok := ch.(interface{ SetOwner(ch Channel) }); ok {
+			setter.SetOwner(ch)
+		}
 		m.channels[name] = ch
 		logger.InfoCF("channels", "Channel enabled successfully", map[string]any{
 			"channel": displayName,
@@ -690,6 +715,16 @@ func (m *Manager) runTTLJanitor(ctx context.Context) {
 				}
 				return true
 			})
+			m.reactionUndos.Range(func(key, value any) bool {
+				if entry, ok := value.(reactionEntry); ok {
+					if now.Sub(entry.createdAt) > typingStopTTL {
+						if _, loaded := m.reactionUndos.LoadAndDelete(key); loaded {
+							entry.undo() // idempotent, safe
+						}
+					}
+				}
+				return true
+			})
 			m.placeholders.Range(func(key, value any) bool {
 				if entry, ok := value.(placeholderEntry); ok {
 					if now.Sub(entry.createdAt) > placeholderTTL {

pkg/channels/onebot/onebot.go

@@ -23,21 +23,20 @@ import (
 
 type OneBotChannel struct {
 	*channels.BaseChannel
-	config          config.OneBotConfig
-	conn            *websocket.Conn
-	ctx             context.Context
-	cancel          context.CancelFunc
-	dedup           map[string]struct{}
-	dedupRing       []string
-	dedupIdx        int
-	mu              sync.Mutex
-	writeMu         sync.Mutex
-	echoCounter     int64
-	selfID          int64
-	pending         map[string]chan json.RawMessage
-	pendingMu       sync.Mutex
-	lastMessageID   sync.Map
-	pendingEmojiMsg sync.Map
+	config        config.OneBotConfig
+	conn          *websocket.Conn
+	ctx           context.Context
+	cancel        context.CancelFunc
+	dedup         map[string]struct{}
+	dedupRing     []string
+	dedupIdx      int
+	mu            sync.Mutex
+	writeMu       sync.Mutex
+	echoCounter   int64
+	selfID        int64
+	pending       map[string]chan json.RawMessage
+	pendingMu     sync.Mutex
+	lastMessageID sync.Map
 }
 
 type oneBotRawEvent struct {
@@ -129,6 +128,22 @@ func (c *OneBotChannel) setMsgEmojiLike(messageID string, emojiID int, set bool)
 	}()
 }
 
+// ReactToMessage implements channels.ReactionCapable.
+// It adds an emoji reaction (ID 289) to group messages and returns an undo function.
+// Private messages return a no-op since reactions are only meaningful in groups.
+func (c *OneBotChannel) ReactToMessage(ctx context.Context, chatID, messageID string) (func(), error) {
+	// Only react in group chats
+	if !strings.HasPrefix(chatID, "group:") {
+		return func() {}, nil
+	}
+
+	c.setMsgEmojiLike(messageID, 289, true)
+
+	return func() {
+		c.setMsgEmojiLike(messageID, 289, false)
+	}, nil
+}
+
 func (c *OneBotChannel) Start(ctx context.Context) error {
 	if c.config.WSUrl == "" {
 		return fmt.Errorf("OneBot ws_url not configured")
@@ -1044,18 +1059,6 @@ func (c *OneBotChannel) handleMessage(raw *oneBotRawEvent) {
 
 	c.lastMessageID.Store(chatID, messageID)
 
-	if raw.MessageType == "group" && messageID != "" && messageID != "0" {
-		c.setMsgEmojiLike(messageID, 289, true)
-		c.pendingEmojiMsg.Store(chatID, messageID)
-		// Register emoji stop with Manager for outbound orchestration
-		if rec := c.GetPlaceholderRecorder(); rec != nil {
-			capturedMsgID := messageID
-			rec.RecordTypingStop("onebot", chatID, func() {
-				c.setMsgEmojiLike(capturedMsgID, 289, false)
-			})
-		}
-	}
-
 	senderInfo := bus.SenderInfo{
 		Platform:    "onebot",
 		PlatformID:  senderID,

pkg/channels/pico/pico.go

@@ -171,6 +171,32 @@ func (c *PicoChannel) StartTyping(ctx context.Context, chatID string) (func(), e
 	}, nil
 }
 
+// SendPlaceholder implements channels.PlaceholderCapable.
+// It sends a placeholder message via the Pico Protocol that will later be
+// edited to the actual response via EditMessage (channels.MessageEditor).
+func (c *PicoChannel) SendPlaceholder(ctx context.Context, chatID string) (string, error) {
+	if !c.config.Placeholder.Enabled {
+		return "", nil
+	}
+
+	text := c.config.Placeholder.Text
+	if text == "" {
+		text = "Thinking... 💭"
+	}
+
+	msgID := uuid.New().String()
+	outMsg := newMessage(TypeMessageCreate, map[string]any{
+		"content":    text,
+		"message_id": msgID,
+	})
+
+	if err := c.broadcastToSession(chatID, outMsg); err != nil {
+		return "", err
+	}
+
+	return msgID, nil
+}
+
 // broadcastToSession sends a message to all connections with a matching session.
 func (c *PicoChannel) broadcastToSession(chatID string, msg PicoMessage) error {
 	// chatID format: "pico:<sessionID>"
@@ -413,14 +439,6 @@ func (c *PicoChannel) handleMessageSend(pc *picoConn, msg PicoMessage) {
 		"preview":    truncate(content, 50),
 	})
 
-	// Register typing with Manager
-	if rec := c.GetPlaceholderRecorder(); rec != nil {
-		stop, err := c.StartTyping(c.ctx, chatID)
-		if err == nil {
-			rec.RecordTypingStop("pico", chatID, stop)
-		}
-	}
-
 	sender := bus.SenderInfo{
 		Platform:    "pico",
 		PlatformID:  senderID,

pkg/channels/slack/slack.go

@@ -200,6 +200,28 @@ func (c *SlackChannel) SendMedia(ctx context.Context, msg bus.OutboundMediaMessa
 	return nil
 }
 
+// ReactToMessage implements channels.ReactionCapable.
+// It adds an "eyes" (👀) reaction to the inbound message and returns an undo function
+// that removes the reaction.
+func (c *SlackChannel) ReactToMessage(ctx context.Context, chatID, messageID string) (func(), error) {
+	channelID, _ := parseSlackChatID(chatID)
+	if channelID == "" {
+		return func() {}, nil
+	}
+
+	c.api.AddReaction("eyes", slack.ItemRef{
+		Channel:   channelID,
+		Timestamp: messageID,
+	})
+
+	return func() {
+		c.api.RemoveReaction("eyes", slack.ItemRef{
+			Channel:   channelID,
+			Timestamp: messageID,
+		})
+	}, nil
+}
+
 func (c *SlackChannel) eventLoop() {
 	for {
 		select {
@@ -275,23 +297,6 @@ func (c *SlackChannel) handleMessageEvent(ev *slackevents.MessageEvent) {
 		chatID = channelID + "/" + threadTS
 	}
 
-	c.api.AddReaction("eyes", slack.ItemRef{
-		Channel:   channelID,
-		Timestamp: messageTS,
-	})
-
-	// Register typing stop (remove "eyes" reaction) with Manager
-	if rec := c.GetPlaceholderRecorder(); rec != nil {
-		capturedChannelID := channelID
-		capturedMessageTS := messageTS
-		rec.RecordTypingStop("slack", chatID, func() {
-			c.api.RemoveReaction("eyes", slack.ItemRef{
-				Channel:   capturedChannelID,
-				Timestamp: capturedMessageTS,
-			})
-		})
-	}
-
 	c.pendingAcks.Store(chatID, slackMessageRef{
 		ChannelID: channelID,
 		Timestamp: messageTS,
@@ -402,23 +407,6 @@ func (c *SlackChannel) handleAppMention(ev *slackevents.AppMentionEvent) {
 		chatID = channelID + "/" + messageTS
 	}
 
-	c.api.AddReaction("eyes", slack.ItemRef{
-		Channel:   channelID,
-		Timestamp: messageTS,
-	})
-
-	// Register typing stop (remove "eyes" reaction) with Manager
-	if rec := c.GetPlaceholderRecorder(); rec != nil {
-		capturedChannelID := channelID
-		capturedMessageTS := messageTS
-		rec.RecordTypingStop("slack", chatID, func() {
-			c.api.RemoveReaction("eyes", slack.ItemRef{
-				Channel:   capturedChannelID,
-				Timestamp: capturedMessageTS,
-			})
-		})
-	}
-
 	c.pendingAcks.Store(chatID, slackMessageRef{
 		ChannelID: channelID,
 		Timestamp: messageTS,

pkg/channels/telegram/telegram.go

@@ -191,6 +191,36 @@ func (c *TelegramChannel) Send(ctx context.Context, msg bus.OutboundMessage) err
 	return nil
 }
 
+// StartTyping implements channels.TypingCapable.
+// It sends ChatAction(typing) immediately and then repeats every 4 seconds
+// (Telegram's typing indicator expires after ~5s) in a background goroutine.
+// The returned stop function is idempotent and cancels the goroutine.
+func (c *TelegramChannel) StartTyping(ctx context.Context, chatID string) (func(), error) {
+	cid, err := parseChatID(chatID)
+	if err != nil {
+		return func() {}, err
+	}
+
+	// Send the first typing action immediately
+	_ = c.bot.SendChatAction(ctx, tu.ChatAction(tu.ID(cid), telego.ChatActionTyping))
+
+	typingCtx, cancel := context.WithCancel(ctx)
+	go func() {
+		ticker := time.NewTicker(4 * time.Second)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-typingCtx.Done():
+				return
+			case <-ticker.C:
+				_ = c.bot.SendChatAction(typingCtx, tu.ChatAction(tu.ID(cid), telego.ChatActionTyping))
+			}
+		}
+	}()
+
+	return cancel, nil
+}
+
 // EditMessage implements channels.MessageEditor.
 func (c *TelegramChannel) EditMessage(ctx context.Context, chatID string, messageID string, content string) error {
 	cid, err := parseChatID(chatID)
@@ -208,6 +238,33 @@ func (c *TelegramChannel) EditMessage(ctx context.Context, chatID string, messag
 	return err
 }
 
+// SendPlaceholder implements channels.PlaceholderCapable.
+// It sends a placeholder message (e.g. "Thinking... 💭") that will later be
+// edited to the actual response via EditMessage (channels.MessageEditor).
+func (c *TelegramChannel) SendPlaceholder(ctx context.Context, chatID string) (string, error) {
+	phCfg := c.config.Channels.Telegram.Placeholder
+	if !phCfg.Enabled {
+		return "", nil
+	}
+
+	text := phCfg.Text
+	if text == "" {
+		text = "Thinking... 💭"
+	}
+
+	cid, err := parseChatID(chatID)
+	if err != nil {
+		return "", err
+	}
+
+	pMsg, err := c.bot.SendMessage(ctx, tu.Message(tu.ID(cid), text))
+	if err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%d", pMsg.MessageID), nil
+}
+
 // SendMedia implements the channels.MediaSender interface.
 func (c *TelegramChannel) SendMedia(ctx context.Context, msg bus.OutboundMediaMessage) error {
 	if !c.IsRunning() {
@@ -419,30 +476,7 @@ func (c *TelegramChannel) handleMessage(ctx context.Context, message *telego.Mes
 		"preview":   utils.Truncate(content, 50),
 	})
 
-	// Thinking indicator
-	err := c.bot.SendChatAction(ctx, tu.ChatAction(tu.ID(chatID), telego.ChatActionTyping))
-	if err != nil {
-		logger.ErrorCF("telegram", "Failed to send chat action", map[string]any{
-			"error": err.Error(),
-		})
-	}
-
-	// Create cancel function for thinking state and register with Manager
-	_, thinkCancel := context.WithTimeout(ctx, 5*time.Minute)
-	if rec := c.GetPlaceholderRecorder(); rec != nil {
-		rec.RecordTypingStop("telegram", chatIDStr, thinkCancel)
-	} else {
-		// No recorder — cancel immediately to avoid context leak
-		thinkCancel()
-	}
-
-	pMsg, err := c.bot.SendMessage(ctx, tu.Message(tu.ID(chatID), "Thinking... 💭"))
-	if err == nil {
-		pID := pMsg.MessageID
-		if rec := c.GetPlaceholderRecorder(); rec != nil {
-			rec.RecordPlaceholder("telegram", chatIDStr, fmt.Sprintf("%d", pID))
-		}
-	}
+	// Placeholder is now auto-triggered by BaseChannel.HandleMessage via PlaceholderCapable
 
 	peerKind := "direct"
 	peerID := fmt.Sprintf("%d", user.ID)

pkg/config/config.go

@@ -288,7 +288,6 @@ type SlackConfig struct {
 	AllowFrom    FlexibleStringSlice `json:"allow_from"              env:"PICOCLAW_CHANNELS_SLACK_ALLOW_FROM"`
 	GroupTrigger GroupTriggerConfig  `json:"group_trigger,omitempty"`
 	Typing       TypingConfig        `json:"typing,omitempty"`
-	Placeholder  PlaceholderConfig   `json:"placeholder,omitempty"`
 }
 
 type LINEConfig struct {
@@ -301,7 +300,6 @@ type LINEConfig struct {
 	AllowFrom          FlexibleStringSlice `json:"allow_from"              env:"PICOCLAW_CHANNELS_LINE_ALLOW_FROM"`
 	GroupTrigger       GroupTriggerConfig  `json:"group_trigger,omitempty"`
 	Typing             TypingConfig        `json:"typing,omitempty"`
-	Placeholder        PlaceholderConfig   `json:"placeholder,omitempty"`
 }
 
 type OneBotConfig struct {
@@ -313,7 +311,6 @@ type OneBotConfig struct {
 	AllowFrom          FlexibleStringSlice `json:"allow_from"              env:"PICOCLAW_CHANNELS_ONEBOT_ALLOW_FROM"`
 	GroupTrigger       GroupTriggerConfig  `json:"group_trigger,omitempty"`
 	Typing             TypingConfig        `json:"typing,omitempty"`
-	Placeholder        PlaceholderConfig   `json:"placeholder,omitempty"`
 }
 
 type WeComConfig struct {
@@ -354,6 +351,7 @@ type PicoConfig struct {
 	WriteTimeout    int                 `json:"write_timeout,omitempty"`
 	MaxConnections  int                 `json:"max_connections,omitempty"`
 	AllowFrom       FlexibleStringSlice `json:"allow_from"                  env:"PICOCLAW_CHANNELS_PICO_ALLOW_FROM"`
+	Placeholder     PlaceholderConfig   `json:"placeholder,omitempty"`
 }
 
 type HeartbeatConfig struct {