Just the tricky solution left

algebraic_steps.py

@@ -410,7 +410,7 @@ def distribute_step(equation):
     left_expr = parse_expr(left, transformations=transformations, evaluate=False)
     right_expr = parse_expr(right, transformations=transformations, evaluate=False)
     
-    print(f"calling distribute_once with expression: {sstr(left_expr)}")
+    #print(f"calling distribute_once with expression: {sstr(left_expr)}")
     new_left_expr, distributed = distribute_once(left_expr)
     
     if distributed != None:
@@ -423,10 +423,15 @@ def distribute_step(equation):
     return steps
     
 def build_ordered_add(args):
-    expr = args[0]
-    for a in args[1:]:
-        expr = Add(expr, a, evaluate=False)
-    return expr    
+    flat_args = []
+
+    for arg in args:
+        if arg.is_Add:
+            flat_args.extend(arg.args)
+        else:
+            flat_args.append(arg)
+
+    return Add(*flat_args, evaluate=False)
     
 def distribute_once(expr):
     expr = flatten_mul(expr)
@@ -437,14 +442,14 @@ def distribute_once(expr):
     # ------------------------------------------------------------
     if expr.is_Mul:
 
-        print(f"expr: {sstr(expr)}")
+        #print(f"expr: {sstr(expr)}")
 
         add_part = None
         other_parts = []
 
         # extract Add factor + everything else
         for arg in expr.args:
-            print(f"arg: {sstr(arg)}")
+            #print(f"arg: {sstr(arg)}")
 
             if arg.is_Add and add_part is None:
                 add_part = arg
@@ -455,7 +460,7 @@ def distribute_once(expr):
         # DISTRIBUTION RULE
         # --------------------------------------------------------
         if add_part is not None:
-            print(f"expr used: {sstr(expr)}, add used: {sstr(add_part)}")
+            #print(f"expr used: {sstr(expr)}, add used: {sstr(add_part)}")
 
             distributed_value = Mul(*other_parts)
 
@@ -472,7 +477,7 @@ def distribute_once(expr):
     # STEP 2: PRIORITY-BASED RECURSION (IMPORTANT FIX)
     # ------------------------------------------------------------
     if expr.args:
-        print(f"step2 args:{expr.args}")
+        #print(f"step2 args:{expr.args}")
         # PASS 1: ONLY distributable Mul(Add(...))
         for i, arg in enumerate(expr.args):
             if arg.is_Mul and arg.has(Add):