diff --git a/apps/sim/app/api/auth/shopify/authorize/route.ts b/apps/sim/app/api/auth/shopify/authorize/route.ts
index 6bb1a94ffd9..43be71dfd17 100644
--- a/apps/sim/app/api/auth/shopify/authorize/route.ts
+++ b/apps/sim/app/api/auth/shopify/authorize/route.ts
@@ -1,7 +1,10 @@
 import { createLogger } from '@sim/logger'
 import { generateId } from '@sim/utils/id'
 import { type NextRequest, NextResponse } from 'next/server'
-import { shopifyAuthorizeQuerySchema } from '@/lib/api/contracts/oauth-connections'
+import {
+  shopifyAuthorizeQuerySchema,
+  shopifyShopDomainSchema,
+} from '@/lib/api/contracts/oauth-connections'
 import { getSession } from '@/lib/auth'
 import { env } from '@/lib/core/config/env'
 import { getBaseUrl } from '@/lib/core/utils/urls'
@@ -161,6 +164,11 @@ export const GET = withRouteHandler(async (request: NextRequest) => {
       cleanShop = `${cleanShop.replace('.myshopify.com', '')}.myshopify.com`
     }
 
+    if (!shopifyShopDomainSchema.safeParse(cleanShop).success) {
+      logger.warn('Rejected invalid Shopify shop domain', { shop: shopDomain })
+      return NextResponse.json({ error: 'Invalid Shopify shop domain' }, { status: 400 })
+    }
+
     const baseUrl = getBaseUrl()
     const redirectUri = `${baseUrl}/api/auth/oauth2/callback/shopify`
 
diff --git a/apps/sim/app/api/workflows/middleware.test.ts b/apps/sim/app/api/workflows/middleware.test.ts
new file mode 100644
index 00000000000..996466426da
--- /dev/null
+++ b/apps/sim/app/api/workflows/middleware.test.ts
@@ -0,0 +1,130 @@
+/**
+ * Tests for workflow access middleware — focused on the workspace-scoped
+ * API key boundary check in the `requireDeployment=false` branch.
+ *
+ * @vitest-environment node
+ */
+
+import {
+  hybridAuthMockFns,
+  workflowAuthzMock,
+  workflowAuthzMockFns,
+  workflowsUtilsMock,
+  workflowsUtilsMockFns,
+} from '@sim/testing'
+import { NextRequest } from 'next/server'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+vi.mock('@/lib/workflows/utils', () => workflowsUtilsMock)
+vi.mock('@sim/workflow-authz', () => workflowAuthzMock)
+vi.mock('@/lib/api-key/service', () => ({
+  authenticateApiKeyFromHeader: vi.fn(),
+  updateApiKeyLastUsed: vi.fn(),
+}))
+
+import { validateWorkflowAccess } from '@/app/api/workflows/middleware'
+
+function makeRequest() {
+  return new NextRequest(new URL('https://example.com/api/workflows/wf-1/log'))
+}
+
+describe('validateWorkflowAccess (requireDeployment=false)', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    workflowsUtilsMockFns.mockGetWorkflowById.mockResolvedValue({
+      id: 'wf-1',
+      workspaceId: 'ws-A',
+      isDeployed: true,
+    })
+    workflowAuthzMockFns.mockAuthorizeWorkflowByWorkspacePermission.mockResolvedValue({
+      allowed: true,
+      status: 200,
+      workflow: { id: 'wf-1', workspaceId: 'ws-A' },
+    })
+  })
+
+  it('rejects a workspace-scoped API key issued for a different workspace', async () => {
+    hybridAuthMockFns.mockCheckHybridAuth.mockResolvedValueOnce({
+      success: true,
+      userId: 'user-1',
+      authType: 'api_key',
+      apiKeyType: 'workspace',
+      workspaceId: 'ws-B',
+    })
+
+    const result = await validateWorkflowAccess(makeRequest(), 'wf-1', false)
+
+    expect(result.error).toEqual({
+      message: 'API key is not authorized for this workspace',
+      status: 403,
+    })
+    expect(workflowAuthzMockFns.mockAuthorizeWorkflowByWorkspacePermission).not.toHaveBeenCalled()
+  })
+
+  it('allows a workspace-scoped API key issued for the matching workspace', async () => {
+    hybridAuthMockFns.mockCheckHybridAuth.mockResolvedValueOnce({
+      success: true,
+      userId: 'user-1',
+      authType: 'api_key',
+      apiKeyType: 'workspace',
+      workspaceId: 'ws-A',
+    })
+
+    const result = await validateWorkflowAccess(makeRequest(), 'wf-1', false)
+
+    expect(result.error).toBeUndefined()
+    expect(result.workflow).toBeDefined()
+    expect(result.auth?.workspaceId).toBe('ws-A')
+    expect(workflowAuthzMockFns.mockAuthorizeWorkflowByWorkspacePermission).toHaveBeenCalledWith({
+      workflowId: 'wf-1',
+      userId: 'user-1',
+      action: 'read',
+    })
+  })
+
+  it('allows a personal API key regardless of workspaceId on the auth result', async () => {
+    hybridAuthMockFns.mockCheckHybridAuth.mockResolvedValueOnce({
+      success: true,
+      userId: 'user-1',
+      authType: 'api_key',
+      apiKeyType: 'personal',
+      workspaceId: 'ws-B',
+    })
+
+    const result = await validateWorkflowAccess(makeRequest(), 'wf-1', false)
+
+    expect(result.error).toBeUndefined()
+    expect(result.workflow).toBeDefined()
+  })
+
+  it('allows session auth (no apiKeyType) when workspace permission grants access', async () => {
+    hybridAuthMockFns.mockCheckHybridAuth.mockResolvedValueOnce({
+      success: true,
+      userId: 'user-1',
+      authType: 'session',
+    })
+
+    const result = await validateWorkflowAccess(makeRequest(), 'wf-1', false)
+
+    expect(result.error).toBeUndefined()
+    expect(result.workflow).toBeDefined()
+  })
+
+  it('still enforces workspace-permission rejection for personal keys', async () => {
+    hybridAuthMockFns.mockCheckHybridAuth.mockResolvedValueOnce({
+      success: true,
+      userId: 'user-1',
+      authType: 'api_key',
+      apiKeyType: 'personal',
+    })
+    workflowAuthzMockFns.mockAuthorizeWorkflowByWorkspacePermission.mockResolvedValueOnce({
+      allowed: false,
+      status: 403,
+      message: 'Access denied',
+    })
+
+    const result = await validateWorkflowAccess(makeRequest(), 'wf-1', false)
+
+    expect(result.error).toEqual({ message: 'Access denied', status: 403 })
+  })
+})
diff --git a/apps/sim/app/api/workflows/middleware.ts b/apps/sim/app/api/workflows/middleware.ts
index 2a66a616c77..10fa3017727 100644
--- a/apps/sim/app/api/workflows/middleware.ts
+++ b/apps/sim/app/api/workflows/middleware.ts
@@ -54,6 +54,15 @@ export async function validateWorkflowAccess(
         }
       }
 
+      if (auth.apiKeyType === 'workspace' && auth.workspaceId !== workflow.workspaceId) {
+        return {
+          error: {
+            message: 'API key is not authorized for this workspace',
+            status: 403,
+          },
+        }
+      }
+
       const authorization = await authorizeWorkflowByWorkspacePermission({
         workflowId,
         userId: auth.userId,
diff --git a/apps/sim/lib/api/contracts/oauth-connections.ts b/apps/sim/lib/api/contracts/oauth-connections.ts
index 03ec64d0a66..4915f2fd712 100644
--- a/apps/sim/lib/api/contracts/oauth-connections.ts
+++ b/apps/sim/lib/api/contracts/oauth-connections.ts
@@ -143,7 +143,7 @@ export const oauthAuthorizeParamsResponseSchema = z.object({
   response_type: z.literal('code'),
 })
 
-const SHOPIFY_SHOP_DOMAIN_REGEX = /^[a-zA-Z0-9][a-zA-Z0-9-]*\.myshopify\.com$/
+const SHOPIFY_SHOP_DOMAIN_REGEX = /^[a-z0-9][a-z0-9-]{1,61}[a-z0-9]\.myshopify\.com$/
 export const shopifyShopDomainSchema = z.string().regex(SHOPIFY_SHOP_DOMAIN_REGEX)
 
 export const listOAuthConnectionsContract = defineRouteContract({