fix(streaming): prevent mid-run stream content loss on Telegram

- Skip FinalizeStream on tool.call — keep streamed message visible
- Gate tool_status placeholder_update to non-streaming runs only
- Prevents streamed text from being overwritten by tool status emoji

internal/channels/events.go

@@ -70,8 +70,6 @@ func (m *Manager) HandleAgentEvent(eventType, runID string, payload any) {
 			// Stop the current stream (reasoning or answer) and finalize only
 			// the answer stream (reasoning messages stay visible).
 			rc.mu.Lock()
-			// Capture current state before resetting for next iteration.
-			wasReasoningStream := rc.hasThinking && !rc.thinkingDone
 			currentStream := rc.stream
 			rc.stream = nil
 			rc.inToolPhase = true
@@ -84,17 +82,18 @@ func (m *Manager) HandleAgentEvent(eventType, runID string, payload any) {
 				if err := currentStream.Stop(ctx); err != nil {
 					slog.Debug("stream tool-phase stop failed", "channel", rc.ChannelName, "error", err)
 				}
-				// Only finalize answer streams (hand off messageID to Send()).
-				// Reasoning streams stay as visible messages — don't put their
-				// messageID into placeholders or it would confuse Send().
-				if !wasReasoningStream {
-					sc.FinalizeStream(ctx, rc.ChatID, currentStream)
-				}
+				// Don't finalize mid-run streams — their messageID must NOT go
+				// into placeholders. Otherwise tool_status placeholder_update
+				// overwrites streamed content, and subsequent FinalizeStream
+				// calls overwrite the placeholder key, leaving earlier messages
+				// stuck at tool status text. Only run.completed finalizes.
 			}
 
-			// Show tool status in streaming preview (edit placeholder with tool name).
+			// Show tool status by editing placeholder message (non-streaming only).
+			// Streaming channels show tool status via reaction emoji instead —
+			// editing the placeholder would overwrite streamed content.
 			toolName := extractPayloadString(payload, "name")
-			if toolName != "" && rc.ToolStatusEnabled {
+			if toolName != "" && rc.ToolStatusEnabled && !rc.Streaming {
 				statusText := formatToolStatus(toolName)
 				outMeta := copyRoutingMeta(rc.Metadata)
 				outMeta["placeholder_update"] = "true"