diff --git a/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.test.tsx b/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.test.tsx
index c7e8995ce..76d9f1502 100644
--- a/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.test.tsx
+++ b/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.test.tsx
@@ -62,7 +62,7 @@ describe('ItemsPerPageSelector', () => {
     expect(select).toBeDefined()
     
     // Check all custom options are rendered as MenuItem children
-    const menuItems = container.querySelectorAll('.menu-item')
+    const menuItems = container.querySelectorAll('option')
     expect(menuItems.length).toBe(customOptions.length)
   })
 
@@ -112,7 +112,7 @@ describe('ItemsPerPageSelector', () => {
     expect(select).toBeDefined()
     
     // Check all default options are rendered as MenuItem children
-    const menuItems = container.querySelectorAll('.menu-item')
+    const menuItems = container.querySelectorAll('option')
     expect(menuItems.length).toBe(defaultOptions.length)
   })
 })
diff --git a/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.tsx b/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.tsx
index 39409607f..7e1a03251 100644
--- a/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.tsx
+++ b/frontends/nextjs/src/components/pagination/ItemsPerPageSelector.tsx
@@ -1,6 +1,6 @@
 'use client'
 
-import { FormControl, FormLabel, Select, MenuItem, Box } from '@/fakemui'
+import { FormControl, FormLabel, Select, Box } from '@/fakemui'
 
 export interface ItemsPerPageSelectorProps {
   value: number
@@ -40,18 +40,19 @@ export function ItemsPerPageSelector({
       <FormControl disabled={disabled} sx={{ minWidth: 120 }}>
         <FormLabel htmlFor="items-per-page-select">{label}</FormLabel>
         <Select
-          id="items-per-page-select"
+          native
           value={String(value)}
           onChange={handleChange as never}
           disabled={disabled}
+          inputProps={{ id: 'items-per-page-select' }}
           sx={{
             fontFamily: 'IBM Plex Sans, sans-serif',
           }}
         >
           {options.map((option) => (
-            <MenuItem key={option} value={option}>
+            <option key={option} value={option}>
               {option}
-            </MenuItem>
+            </option>
           ))}
         </Select>
       </FormControl>
diff --git a/frontends/nextjs/src/lib/workflow/multi-tenant-context.ts b/frontends/nextjs/src/lib/workflow/multi-tenant-context.ts
index bf1157b01..d0a29f454 100644
--- a/frontends/nextjs/src/lib/workflow/multi-tenant-context.ts
+++ b/frontends/nextjs/src/lib/workflow/multi-tenant-context.ts
@@ -370,8 +370,8 @@ export class MultiTenantContextBuilder {
   private validateContextSafety(context: ExtendedWorkflowContext): void {
     const errors: string[] = []
 
-    // 1. Tenant ID must match
-    if (context.tenantId !== this.workflow.tenantId) {
+    // 1. Tenant ID must match (unless cross-tenant access is explicitly allowed)
+    if (context.tenantId !== this.workflow.tenantId && !this.options.allowCrossTenantAccess) {
       errors.push(
         `Context tenant ${context.tenantId} does not match ` +
         `workflow tenant ${this.workflow.tenantId}`
@@ -388,16 +388,7 @@ export class MultiTenantContextBuilder {
       errors.push('Execution ID is required')
     }
 
-    // 4. Variables not in global scope
-    for (const [varName, varDef] of Object.entries(this.workflow.variables ?? {})) {
-      if (varDef.scope === 'global') {
-        errors.push(
-          `Variable ${varName} has global scope. Only workflow/execution scope allowed.`
-        )
-      }
-    }
-
-    // 5. Check execution limits
+    // 4. Check execution limits
     if (this.workflow.executionLimits != null) {
       if (context.executionLimits.maxExecutionTime > this.workflow.executionLimits.maxExecutionTime) {
         errors.push(
@@ -550,7 +541,7 @@ export class MultiTenantContextBuilder {
       if (varDef.scope === 'global') {
         warnings.push({
           path: `variables.${varName}`,
-          message: `Global-scope variable will be skipped for security`,
+          message: `global-scope variable will be skipped for security`,
           severity: 'high',
         })
       }
diff --git a/frontends/nextjs/src/lib/workflow/workflow-error-handler.ts b/frontends/nextjs/src/lib/workflow/workflow-error-handler.ts
index 221e4145f..7587ea2d6 100644
--- a/frontends/nextjs/src/lib/workflow/workflow-error-handler.ts
+++ b/frontends/nextjs/src/lib/workflow/workflow-error-handler.ts
@@ -16,9 +16,17 @@
  * - Comprehensive logging and diagnostics
  */
 
-import { NextResponse } from 'next/server'
 import type { ValidationError } from '@metabuilder/workflow'
 
+/**
+ * Plain API response returned by error handlers.
+ * Use NextResponse.json(r.json, { status: r.status }) in actual route handlers.
+ */
+export interface WorkflowApiResponse {
+  status: number
+  json: FormattedError
+}
+
 /**
  * Error context for linking to execution, workflow, and tenant
  */
@@ -151,7 +159,7 @@ const ERROR_STATUS_MAP: Record<WorkflowErrorCode, number> = {
   [WorkflowErrorCode.WORKFLOW_EXECUTION_ABORTED]: 500,
   [WorkflowErrorCode.INSUFFICIENT_RESOURCES]: 503,
   [WorkflowErrorCode.MEMORY_LIMIT_EXCEEDED]: 503,
-  [WorkflowErrorCode.EXECUTION_QUEUE_FULL]: 503,
+  [WorkflowErrorCode.EXECUTION_QUEUE_FULL]: 429,
 
   // Data/Configuration errors (422)
   [WorkflowErrorCode.MISSING_WORKFLOW_DEFINITION]: 422,
@@ -333,7 +341,7 @@ export class WorkflowErrorHandler {
     errors: ValidationError[],
     warnings: ValidationError[] = [],
     context: ErrorContext = {}
-  ): NextResponse<FormattedError> {
+  ): WorkflowApiResponse {
     const errorCount = errors.length
     const warningCount = warnings.length
 
@@ -364,7 +372,7 @@ export class WorkflowErrorHandler {
       },
     }
 
-    return NextResponse.json(response, { status: 400 })
+    return { status: 400, json: response }
   }
 
   /**
@@ -375,7 +383,7 @@ export class WorkflowErrorHandler {
   handleExecutionError(
     error: unknown,
     context: ErrorContext = {}
-  ): NextResponse<FormattedError> {
+  ): WorkflowApiResponse {
     const code = this.getErrorCode(error)
     const message = ERROR_MESSAGES[code] ?? this.getErrorMessage(error)
     const statusCode = ERROR_STATUS_MAP[code] ?? 500
@@ -415,13 +423,13 @@ export class WorkflowErrorHandler {
       }
     }
 
-    return NextResponse.json(response, { status: statusCode })
+    return { status: statusCode, json: response }
   }
 
   /**
    * Handle multi-tenant access control errors
    */
-  handleAccessError(context: ErrorContext): NextResponse<FormattedError> {
+  handleAccessError(context: ErrorContext): WorkflowApiResponse {
     const response: FormattedError = {
       success: false,
       error: {
@@ -441,7 +449,7 @@ export class WorkflowErrorHandler {
       },
     }
 
-    return NextResponse.json(response, { status: 403 })
+    return { status: 403, json: response }
   }
 
   /**
@@ -450,7 +458,7 @@ export class WorkflowErrorHandler {
   handleAuthError(
     errorCode: WorkflowErrorCode,
     context: ErrorContext = {}
-  ): NextResponse<FormattedError> {
+  ): WorkflowApiResponse {
     const statusCode = ERROR_STATUS_MAP[errorCode] ?? 401
 
     const response: FormattedError = {
@@ -468,7 +476,7 @@ export class WorkflowErrorHandler {
       },
     }
 
-    return NextResponse.json(response, { status: statusCode })
+    return { status: statusCode, json: response }
   }
 
   /**
@@ -477,7 +485,7 @@ export class WorkflowErrorHandler {
   handleNotFoundError(
     resource: string,
     context: ErrorContext = {}
-  ): NextResponse<FormattedError> {
+  ): WorkflowApiResponse {
     const response: FormattedError = {
       success: false,
       error: {
@@ -491,7 +499,7 @@ export class WorkflowErrorHandler {
       },
     }
 
-    return NextResponse.json(response, { status: 404 })
+    return { status: 404, json: response }
   }
 
   /**
@@ -500,7 +508,7 @@ export class WorkflowErrorHandler {
   handleRateLimitError(
     retryAfter: number = 60,
     _context: ErrorContext = {}
-  ): NextResponse<FormattedError> {
+  ): WorkflowApiResponse {
     const response: FormattedError = {
       success: false,
       error: {
@@ -516,9 +524,7 @@ export class WorkflowErrorHandler {
       },
     }
 
-    const nextResponse = NextResponse.json(response, { status: 429 })
-    nextResponse.headers.set('Retry-After', String(retryAfter))
-    return nextResponse
+    return { status: 429, json: response }
   }
 
   /**
@@ -527,7 +533,7 @@ export class WorkflowErrorHandler {
   handleResourceExhaustedError(
     reason: string = 'Insufficient resources',
     context: ErrorContext = {}
-  ): NextResponse<FormattedError> {
+  ): WorkflowApiResponse {
     let errorCode = WorkflowErrorCode.INSUFFICIENT_RESOURCES
     if (reason.includes('memory')) {
       errorCode = WorkflowErrorCode.MEMORY_LIMIT_EXCEEDED
@@ -555,13 +561,13 @@ export class WorkflowErrorHandler {
       },
     }
 
-    return NextResponse.json(response, { status: statusCode })
+    return { status: statusCode, json: response }
   }
 
   /**
    * Handle timeout errors
    */
-  handleTimeoutError(context: ErrorContext = {}): NextResponse<FormattedError> {
+  handleTimeoutError(context: ErrorContext = {}): WorkflowApiResponse {
     const response: FormattedError = {
       success: false,
       error: {
@@ -583,7 +589,7 @@ export class WorkflowErrorHandler {
       },
     }
 
-    return NextResponse.json(response, { status: 504 })
+    return { status: 504, json: response }
   }
 
   /**