fix(loops): string loop

sim/executor/loops.ts

@@ -247,7 +247,18 @@ export class LoopManager {
           return [];
         }
         
-        // Simple expression evaluation using Function constructor
+        // First check if it's valid JSON (array or object)
+        if (trimmedExpression.startsWith('[') || trimmedExpression.startsWith('{')) {
+          try {
+            // Try to parse as JSON first
+            return JSON.parse(trimmedExpression);
+          } catch (jsonError) {
+            console.error(`Error parsing JSON for loop ${loopId}:`, jsonError);
+            // If JSON parsing fails, continue with expression evaluation
+          }
+        }
+        
+        // If not valid JSON or JSON parsing failed, try to evaluate as an expression
         const result = new Function('context', `return ${loop.forEachItems}`)(context);
         
         // If the result is an array or object, return it

sim/executor/resolver.ts

@@ -626,12 +626,18 @@ export class InputResolver {
       if (typeof loop.forEachItems === 'string') {
         try {
           // Check if it's valid JSON
-          if (loop.forEachItems.trim().startsWith('[') || loop.forEachItems.trim().startsWith('{')) {
-            return JSON.parse(loop.forEachItems);
+          const trimmedExpression = loop.forEachItems.trim();
+          if (trimmedExpression.startsWith('[') || trimmedExpression.startsWith('{')) {
+            try {
+              // Try to parse as JSON first
+              return JSON.parse(trimmedExpression);
+            } catch (jsonError) {
+              console.error(`Error parsing JSON for loop:`, jsonError);
+              // If JSON parsing fails, continue with expression evaluation
+            }
           }
           
-          // Otherwise, try to evaluate it as an expression
-          const trimmedExpression = loop.forEachItems.trim();
+          // If not valid JSON or JSON parsing failed, try to evaluate as an expression
           if (trimmedExpression && !trimmedExpression.startsWith('//')) {
             const result = new Function('context', `return ${loop.forEachItems}`)(context);
             if (Array.isArray(result) || (typeof result === 'object' && result !== null)) {

sim/stores/workflows/workflow/store.ts

@@ -572,13 +572,14 @@ export const useWorkflowStore = create<WorkflowStoreWithHistory>()(
         ) {
           try {
             // First try to parse to validate it's valid JSON
-            JSON.parse(items);
+            const parsed = JSON.parse(items);
             
             // If parsing succeeds, store the original string to preserve formatting
             // This way we keep the user's exact formatting (spacing, line breaks, etc.)
             parsedItems = items;
           } catch (e) {
-            // If parsing fails, keep it as a string
+            // If parsing fails, keep it as a string expression
+            console.error('Invalid JSON format for forEach items:', e);
             parsedItems = items;
           }
         }