Show complete Display evolution

app.py

@@ -404,17 +404,21 @@ def _trace_rows(events: tuple[dict[str, Any], ...]) -> list[list[Any]]:
 def _display_evolution(events: tuple[dict[str, Any], ...]) -> str:
     changes: list[str] = []
     previous: str | None = None
+    seen_step = False
     for event in events:
         if event.get("kind") != "model_step_finished":
             continue
         payload = event.get("payload", {})
         current = str(payload.get("display_materialized_text", "")).strip()
-        if current and current != previous:
-            changes.append(f"**Step {event.get('step', 0)}** — {current}")
-            previous = current
+        if seen_step and current == previous:
+            continue
+        visible = current or "(empty Display)"
+        changes.append(f"**Step {event.get('step', 0)}** — {visible}")
+        previous = current
+        seen_step = True
     if not changes:
-        return "No materialized Display text was produced before the run ended."
-    return "\n\n".join(changes[-12:])
+        return "No Display states were recorded before the run ended."
+    return "\n\n".join(changes)
 
 
 def _summary_html(summary: dict[str, Any]) -> str: