Update app.py

app.py

@@ -57,15 +57,33 @@ def solve_polynomial(image, llm_url):
 
         try:
             expr = parse_latex(cleaned_latex)
+        
+            # Trigger fallback if not a polynomial (i.e., not a SymPy Equality with a polynomial lhs - rhs)
+            if not isinstance(expr, sp.Equality):
+                raise ValueError("Expression is not an equation.")
+        
+            lhs_minus_rhs = expr.lhs - expr.rhs
+            if not lhs_minus_rhs.is_polynomial():
+                raise ValueError("Expression is not a polynomial.")
+        
         except Exception:
             # Fallback to LLM microservice
-            fixed_latex = request_llm_fallback(cleaned_latex, llm_url)
+            fixed_latex = request_llm_fallback(cleaned_latex)
             cleaned_latex = clean_latex(fixed_latex)
             try:
                 expr = parse_latex(cleaned_latex)
+        
+                # Try again: check if fallback result is polynomial
+                if not isinstance(expr, sp.Equality):
+                    raise ValueError("Expression is not an equation.")
+        
+                lhs_minus_rhs = expr.lhs - expr.rhs
+                if not lhs_minus_rhs.is_polynomial():
+                    raise ValueError("Expression is not a polynomial.")
             except Exception:
                 expr = None
 
+
         if expr is None:
             return (
                 "❌ Could not parse expression even after fallback:\n\n"