fix: clear template on first edit using substring replace, not line matching

app.py

@@ -418,21 +418,21 @@ def build_app() -> gr.Blocks:
 
         # ---- Event wiring ----
 
-        _TEMPLATE_LINES = {
-            "# Write your solution here using Legesher",
-            "# Use native-language variable and function names",
-        }
+        _T1 = "# Write your solution here using Legesher"
+        _T2 = "# Use native-language variable and function names"
+        _TEMPLATE = f"{_T1}\n{_T2}\n"
 
         def on_code_change(code: str, cleared: bool):
-            """Strip template comment lines on the user's very first edit, then never again."""
+            """On the user's first real edit, strip the template strings then never run again."""
             if cleared:
                 return gr.update(), True
-            lines = code.split("\n")
-            filtered = [l for l in lines if l.strip() not in _TEMPLATE_LINES]
-            # Remove leading blank lines left behind
-            while filtered and not filtered[0].strip():
-                filtered.pop(0)
-            cleaned = "\n".join(filtered)
+            # Nothing typed yet — template still untouched
+            if code.strip() in ("", _T1, _T2, f"{_T1}\n{_T2}"):
+                return gr.update(), False
+            # Strip the two template lines wherever they appear via substring replace
+            cleaned = code.replace(_T1 + "\n", "").replace(_T2 + "\n", "")
+            cleaned = cleaned.replace(_T1, "").replace(_T2, "")
+            cleaned = cleaned.lstrip("\n")
             return cleaned, True
 
         code_editor.change(