Keep formula values of computed variables

A variable whose value is a ${= ...} formula is a computed variable the
runtime evaluates; sanitizing it by type wiped it for lists, maps and
numbers.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011fXBKiHRftTsgsVPHEZAWz

Author: claude

lib/src/api/models/variables_model.dart

@@ -195,8 +195,12 @@ class VariableData
 String? sanitizeValueForVariableType(Object? value, VariableType type) {
   if (value == null) return null;
   // if (value.isEmpty) return '';
-  // Do not sanitize if the value contains a variable path.
-  if (value.toString().contains(variablePathPattern)) return value.toString();
+  // Do not sanitize if the value contains a variable path, or is a formula:
+  // a computed variable stores `${= ...}` and the runtime evaluates it.
+  if (value.toString().contains(variablePathPattern) ||
+      value.toString().trimLeft().startsWith(r'${=')) {
+    return value.toString();
+  }
   switch (type) {
     case VariableType.text:
     case VariableType.image:

test/computed_variable_value_test.dart

@@ -0,0 +1,36 @@
+import 'package:codelessly_api/codelessly_api.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('a formula value is kept as is for every variable type', () {
+    const String formula = r"${= filter(units, u => u.status == 'Available')}";
+    for (final VariableType type in VariableType.values) {
+      expect(
+        VariableData(id: 'v', name: 'v', value: formula, type: type).value,
+        formula,
+        reason: '$type',
+      );
+    }
+    expect(
+      VariableData(
+        id: 'v',
+        name: 'v',
+        value: '[]',
+        type: VariableType.list,
+      ).copyWith(value: r'${= range(3)}').value,
+      r'${= range(3)}',
+    );
+  });
+
+  test('other values are still sanitized by type', () {
+    expect(
+      VariableData(
+        id: 'v',
+        name: 'v',
+        value: 'abc',
+        type: VariableType.integer,
+      ).value,
+      isNot('abc'),
+    );
+  });
+}