fix: inject pending assistant reply into inbound turns and fill ReplyToMessageID

Gap 1: regular inbound turns now see the previous assistant reply in LLM context
even when OnDelivered hasn't fired yet (fast follow-up scenario). Achieved by
loading from pendingDeliveries sync.Map after captureRestorePoint and appending
to history before BuildMessages.

Gap 2: HandleMessage in BaseChannel now fills ReplyToMessageID from metadata so
the first-class struct field is populated for all channels that set the key in
metadata (e.g. Telegram).

pkg/agent/loop.go

@@ -58,6 +58,7 @@ type AgentLoop struct {
 	hookRuntime       hookRuntime
 	steering          *steeringQueue
 	pendingSkills     sync.Map
+	pendingDeliveries sync.Map // sessionKey -> string: last undelivered assistant content
 	mu                sync.RWMutex
 
 	// Concurrent turn management (from HEAD)
@@ -1697,9 +1698,14 @@ func (al *AgentLoop) runAgentLoop(
 	}
 
 	if !opts.NoHistory && result.finalContent != "" {
+		// Register the pending content so that fast follow-up inbound turns can
+		// inject it into their LLM context before OnDelivered persists it.
+		al.pendingDeliveries.Store(opts.SessionKey, result.finalContent)
+
 		var once sync.Once
 		response.OnDelivered = func(msgIDs []string) {
 			once.Do(func() {
+				al.pendingDeliveries.Delete(opts.SessionKey)
 				assistantMsg := providers.Message{
 					Role:       "assistant",
 					Content:    result.finalContent,
@@ -1843,6 +1849,20 @@ func (al *AgentLoop) runTurn(ctx context.Context, ts *turnState) (turnResult, er
 	}
 	ts.captureRestorePoint(history, summary)
 
+	// Inject pending undelivered assistant reply into history so regular inbound turns
+	// see it in LLM context even before OnDelivered persists it to session storage.
+	// Only inject if history doesn't already end with an assistant message (avoids duplication
+	// when OnDelivered fires before the next turn starts).
+	if !ts.opts.NoHistory {
+		if pendingRaw, ok := al.pendingDeliveries.Load(ts.sessionKey); ok {
+			if pendingContent, _ := pendingRaw.(string); pendingContent != "" {
+				if len(history) == 0 || history[len(history)-1].Role != "assistant" {
+					history = append(history, providers.Message{Role: "assistant", Content: pendingContent})
+				}
+			}
+		}
+	}
+
 	messages := ts.agent.ContextBuilder.BuildMessages(
 		history,
 		summary,

pkg/channels/base.go

@@ -286,6 +286,7 @@ func (c *BaseChannel) HandleMessage(
 		MessageID:        messageID,
 		MediaScope:       scope,
 		Metadata:         metadata,
+		ReplyToMessageID: metadata["reply_to_message_id"],
 	}
 
 	// Auto-trigger typing indicator, message reaction, and placeholder before publishing.