I can apply formulas

src/myfasthtml/core/formula/engine.py

@@ -96,7 +96,9 @@ class FormulaEngine:
     # Registers in DAG and raises FormulaCycleError if cycle detected
     self._graph.add_formula(table, col, formula)
     self._formulas[(table, col)] = formula
-    
+    # Mark dirty so the column is computed on the next render
+    self._graph.mark_dirty(table, col)
+
     logger.debug("Formula set for %s.%s: %s", table, col, formula_text)
   
   def remove_formula(self, table: str, col: str) -> None: