fix: progress label shows tool call not THINK text during tour generation

React trace events forward the full THINK sentence as the loading
message — it was appearing as a wall of text in the progress overlay.
Fix: backend sends event.tool (short) as message for react events;
frontend caps label at 72 chars as a safety net.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/services/tour_agent.py

@@ -1590,12 +1590,18 @@ Rules:
             if event.get("type") == "result":
                 pipeline_map = event.get("data", {})
                 break
-            # Forward trace events to the UI; advance progress slightly each round
+            # Forward trace events to the UI; advance progress slightly each round.
+            # For react events, show only the tool call as the loading message —
+            # the full THINK text belongs in the trace panel, not the progress label.
             react_prog = min(react_prog + 0.015, 0.24)
+            if event.get("type") == "react":
+                msg = event.get("tool", "") or event.get("text", "")
+            else:
+                msg = event.get("text", "")
             yield {
                 "stage": "mapping",
                 "progress": react_prog,
-                "message": event.get("text", ""),
+                "message": msg,
                 "trace": event,
             }
 

ui/src/components/ExploreView.jsx

@@ -637,7 +637,9 @@ export default function ExploreView({ repo, onAskAbout, onRegenerateRef }) {
   // ── Loading / error states ─────────────────────────────────────────────────
   if (loading) {
     const pct   = loadStage ? Math.round(loadStage.progress * 100) : 0;
-    const label = loadStage?.message || "Building your guided tour…";
+    const rawLabel = loadStage?.message || "Building your guided tour…";
+    // Cap the progress label — long THINK strings must not overflow this area
+    const label = rawLabel.length > 72 ? rawLabel.slice(0, 72) + "…" : rawLabel;
     return (
       <div className="ec-loading" style={{ flexDirection: "column", alignItems: "stretch", gap: 16, maxWidth: 480, margin: "auto" }}>
         {/* Progress row */}