fix(api): classify access-denied and sandbox user-code errors with correct HTTP status

apps/sim/app/api/copilot/chat/queries.ts

@@ -12,13 +12,17 @@ import { normalizeMessage } from '@/lib/copilot/chat/persisted-message'
 import {
   authenticateCopilotRequestSessionOnly,
   createBadRequestResponse,
+  createForbiddenResponse,
   createInternalServerErrorResponse,
   createUnauthorizedResponse,
 } from '@/lib/copilot/request/http'
 import { readFilePreviewSessions } from '@/lib/copilot/request/session'
 import { readEvents } from '@/lib/copilot/request/session/buffer'
 import { toStreamBatchEvent } from '@/lib/copilot/request/session/types'
-import { assertActiveWorkspaceAccess } from '@/lib/workspaces/permissions/utils'
+import {
+  assertActiveWorkspaceAccess,
+  isWorkspaceAccessDeniedError,
+} from '@/lib/workspaces/permissions/utils'
 
 const logger = createLogger('CopilotChatAPI')
 
@@ -196,6 +200,9 @@ export async function GET(req: NextRequest) {
       chats: chats.map(transformChatListItem),
     })
   } catch (error) {
+    if (isWorkspaceAccessDeniedError(error)) {
+      return createForbiddenResponse('Workspace access denied')
+    }
     logger.error('Error fetching copilot chats:', error)
     return createInternalServerErrorResponse('Failed to fetch chats')
   }

apps/sim/app/api/copilot/chats/route.ts

@@ -10,12 +10,16 @@ import { resolveOrCreateChat } from '@/lib/copilot/chat/lifecycle'
 import {
   authenticateCopilotRequestSessionOnly,
   createBadRequestResponse,
+  createForbiddenResponse,
   createInternalServerErrorResponse,
   createUnauthorizedResponse,
 } from '@/lib/copilot/request/http'
 import { taskPubSub } from '@/lib/copilot/tasks'
 import { withRouteHandler } from '@/lib/core/utils/with-route-handler'
-import { assertActiveWorkspaceAccess } from '@/lib/workspaces/permissions/utils'
+import {
+  assertActiveWorkspaceAccess,
+  isWorkspaceAccessDeniedError,
+} from '@/lib/workspaces/permissions/utils'
 
 const logger = createLogger('CopilotChatsListAPI')
 
@@ -138,6 +142,9 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
 
     return NextResponse.json({ success: true, id: result.chatId })
   } catch (error) {
+    if (isWorkspaceAccessDeniedError(error)) {
+      return createForbiddenResponse('Workspace access denied')
+    }
     logger.error('Error creating workflow copilot chat:', error)
     return createInternalServerErrorResponse('Failed to create chat')
   }

apps/sim/app/api/function/execute/route.ts

@@ -1132,7 +1132,7 @@ export const POST = withRouteHandler(async (req: NextRequest) => {
             output: { result: null, stdout: cleanStdout(shellStdout), executionTime },
           },
           routeContext,
-          { status: 500 }
+          { status: 422 }
         )
       }
 
@@ -1269,7 +1269,7 @@ export const POST = withRouteHandler(async (req: NextRequest) => {
               output: { result: null, stdout: cleanedOutput, executionTime },
             },
             routeContext,
-            { status: 500 }
+            { status: 422 }
           )
         }
 
@@ -1356,7 +1356,7 @@ export const POST = withRouteHandler(async (req: NextRequest) => {
             output: { result: null, stdout: cleanedOutput, executionTime },
           },
           routeContext,
-          { status: 500 }
+          { status: 422 }
         )
       }
 

apps/sim/app/api/mothership/chats/[chatId]/fork/route.ts

@@ -11,6 +11,7 @@ import { fetchGo } from '@/lib/copilot/request/go/fetch'
 import {
   authenticateCopilotRequestSessionOnly,
   createBadRequestResponse,
+  createForbiddenResponse,
   createInternalServerErrorResponse,
   createNotFoundResponse,
   createUnauthorizedResponse,
@@ -21,7 +22,10 @@ import { taskPubSub } from '@/lib/copilot/tasks'
 import { env } from '@/lib/core/config/env'
 import { withRouteHandler } from '@/lib/core/utils/with-route-handler'
 import { captureServerEvent } from '@/lib/posthog/server'
-import { assertActiveWorkspaceAccess } from '@/lib/workspaces/permissions/utils'
+import {
+  assertActiveWorkspaceAccess,
+  isWorkspaceAccessDeniedError,
+} from '@/lib/workspaces/permissions/utils'
 
 const logger = createLogger('ForkChatAPI')
 
@@ -150,6 +154,9 @@ export const POST = withRouteHandler(
 
       return NextResponse.json({ success: true, id: newId })
     } catch (error) {
+      if (isWorkspaceAccessDeniedError(error)) {
+        return createForbiddenResponse('Workspace access denied')
+      }
       logger.error('Error forking chat:', error)
       return createInternalServerErrorResponse('Failed to fork chat')
     }

apps/sim/app/api/mothership/chats/route.ts

@@ -11,13 +11,17 @@ import { parseRequest } from '@/lib/api/server'
 import { reconcileChatStreamMarkers } from '@/lib/copilot/chat/stream-liveness'
 import {
   authenticateCopilotRequestSessionOnly,
+  createForbiddenResponse,
   createInternalServerErrorResponse,
   createUnauthorizedResponse,
 } from '@/lib/copilot/request/http'
 import { taskPubSub } from '@/lib/copilot/tasks'
 import { withRouteHandler } from '@/lib/core/utils/with-route-handler'
 import { captureServerEvent } from '@/lib/posthog/server'
-import { assertActiveWorkspaceAccess } from '@/lib/workspaces/permissions/utils'
+import {
+  assertActiveWorkspaceAccess,
+  isWorkspaceAccessDeniedError,
+} from '@/lib/workspaces/permissions/utils'
 
 const logger = createLogger('MothershipChatsAPI')
 
@@ -68,6 +72,9 @@ export const GET = withRouteHandler(async (request: NextRequest) => {
 
     return NextResponse.json({ success: true, data: reconciled })
   } catch (error) {
+    if (isWorkspaceAccessDeniedError(error)) {
+      return createForbiddenResponse('Workspace access denied')
+    }
     logger.error('Error fetching mothership chats:', error)
     return createInternalServerErrorResponse('Failed to fetch chats')
   }
@@ -118,6 +125,9 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
 
     return NextResponse.json({ success: true, id: chat.id })
   } catch (error) {
+    if (isWorkspaceAccessDeniedError(error)) {
+      return createForbiddenResponse('Workspace access denied')
+    }
     logger.error('Error creating mothership chat:', error)
     return createInternalServerErrorResponse('Failed to create chat')
   }

apps/sim/app/api/mothership/execute/route.ts

@@ -19,6 +19,7 @@ import { buildMothershipToolsForRequest } from '@/lib/mothership/settings/runtim
 import {
   assertActiveWorkspaceAccess,
   getUserEntityPermissions,
+  isWorkspaceAccessDeniedError,
 } from '@/lib/workspaces/permissions/utils'
 
 export const maxDuration = 3600
@@ -378,6 +379,10 @@ export const POST = withRouteHandler(async (req: NextRequest) => {
       return NextResponse.json({ error: 'Mothership execution aborted' }, { status: 499 })
     }
 
+    if (isWorkspaceAccessDeniedError(error)) {
+      return NextResponse.json({ error: 'Workspace access denied' }, { status: 403 })
+    }
+
     logger.error(
       messageId ? `Mothership execute error [messageId:${messageId}]` : 'Mothership execute error',
       {

apps/sim/app/api/tools/file/manage/route.ts

@@ -19,7 +19,10 @@ import {
 } from '@/lib/uploads/contexts/workspace/workspace-file-manager'
 import { getFileExtension, getMimeTypeFromExtension } from '@/lib/uploads/utils/file-utils'
 import { performMoveWorkspaceFileItems } from '@/lib/workspace-files/orchestration'
-import { assertActiveWorkspaceAccess } from '@/lib/workspaces/permissions/utils'
+import {
+  assertActiveWorkspaceAccess,
+  isWorkspaceAccessDeniedError,
+} from '@/lib/workspaces/permissions/utils'
 
 export const dynamic = 'force-dynamic'
 
@@ -352,6 +355,12 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
       }
     }
   } catch (error) {
+    if (isWorkspaceAccessDeniedError(error)) {
+      return NextResponse.json(
+        { success: false, error: 'Workspace access denied' },
+        { status: 403 }
+      )
+    }
     const message = getErrorMessage(error, 'Unknown error')
     logger.error('File operation failed', { operation: body.operation, error: message })
     return NextResponse.json({ success: false, error: message }, { status: 500 })

apps/sim/lib/copilot/chat/post.ts

@@ -44,7 +44,10 @@ import { taskPubSub } from '@/lib/copilot/tasks'
 import { prepareExecutionContext } from '@/lib/copilot/tools/handlers/context'
 import { getEffectiveDecryptedEnv } from '@/lib/environment/utils'
 import { getWorkflowById, resolveWorkflowIdForUser } from '@/lib/workflows/utils'
-import { getUserEntityPermissions } from '@/lib/workspaces/permissions/utils'
+import {
+  getUserEntityPermissions,
+  isWorkspaceAccessDeniedError,
+} from '@/lib/workspaces/permissions/utils'
 import type { ChatContext } from '@/stores/panel'
 
 export const maxDuration = 3600
@@ -1039,6 +1042,10 @@ export async function handleUnifiedChatPost(req: NextRequest) {
       return validationErrorResponse(error, 'Invalid request data')
     }
 
+    if (isWorkspaceAccessDeniedError(error)) {
+      return NextResponse.json({ error: 'Workspace access denied' }, { status: 403 })
+    }
+
     logger.error(`[${requestId}] Error handling unified chat request`, {
       error: getErrorMessage(error, 'Unknown error'),
       stack: error instanceof Error ? error.stack : undefined,

apps/sim/lib/copilot/request/http.ts

@@ -35,6 +35,10 @@ export function createBadRequestResponse(message: string): NextResponse {
   return NextResponse.json({ error: message }, { status: 400 })
 }
 
+export function createForbiddenResponse(message: string): NextResponse {
+  return NextResponse.json({ error: message }, { status: 403 })
+}
+
 export function createNotFoundResponse(message: string): NextResponse {
   return NextResponse.json({ error: message }, { status: 404 })
 }

apps/sim/lib/core/utils/with-route-handler.ts

@@ -11,6 +11,26 @@ type RouteHandler<T = unknown> = (
   context: T
 ) => Promise<NextResponse | Response> | NextResponse | Response
 
+/**
+ * Reads a numeric `statusCode` (4xx or 5xx) off an Error so typed domain errors
+ * (e.g. `WorkspaceAccessDeniedError`, `InvalidFieldError`) map to the correct
+ * HTTP status when they bubble up unhandled instead of defaulting to 500.
+ *
+ * When a typed status is returned, the error's `message` is sent to the client
+ * verbatim — matching the NestJS `HttpException` / Spring `ResponseStatusException`
+ * convention. The safety contract is convention-based: only attach `statusCode`
+ * to errors whose `message` is safe to expose to clients (no stack traces,
+ * secrets, file paths, ORM internals). Untyped errors fall back to a generic
+ * 500 response with no message exposure.
+ */
+function readTypedErrorStatus(error: unknown): number | undefined {
+  if (!(error instanceof Error)) return undefined
+  const status = (error as { statusCode?: unknown }).statusCode
+  if (typeof status !== 'number') return undefined
+  if (status < 400 || status >= 600) return undefined
+  return status
+}
+
 /**
  * Wraps a Next.js API route handler with centralized error reporting.
  *
@@ -35,8 +55,21 @@ export function withRouteHandler<T>(handler: RouteHandler<T>): RouteHandler<T> {
       } catch (error) {
         const duration = Date.now() - startTime
         const message = getErrorMessage(error, 'Unknown error')
-        logger.error('Unhandled route error', { duration, error: message })
-        response = NextResponse.json({ error: 'Internal server error', requestId }, { status: 500 })
+        const typedStatus = readTypedErrorStatus(error)
+        if (typedStatus !== undefined) {
+          if (typedStatus >= 500) {
+            logger.error('Unhandled route error', { duration, status: typedStatus, error: message })
+          } else {
+            logger.warn('Typed route error', { duration, status: typedStatus, error: message })
+          }
+          response = NextResponse.json({ error: message, requestId }, { status: typedStatus })
+        } else {
+          logger.error('Unhandled route error', { duration, error: message })
+          response = NextResponse.json(
+            { error: 'Internal server error', requestId },
+            { status: 500 }
+          )
+        }
         response?.headers?.set('x-request-id', requestId)
         return response
       }

apps/sim/lib/workspaces/permissions/utils.ts

@@ -147,13 +147,34 @@ export async function checkWorkspaceAccess(
   return { exists: true, hasAccess: true, canWrite, workspace: ws }
 }
 
+/**
+ * Thrown when a user attempts to access a workspace they don't have access to,
+ * or that doesn't exist / has been archived. Carries `statusCode = 403` so the
+ * centralized route wrapper maps it to HTTP 403 instead of defaulting to 500.
+ * The `message` is intentionally client-safe and is exposed to API responses.
+ */
+export class WorkspaceAccessDeniedError extends Error {
+  readonly statusCode = 403
+  readonly workspaceId: string
+
+  constructor(workspaceId: string) {
+    super(`Workspace access denied: ${workspaceId}`)
+    this.name = 'WorkspaceAccessDeniedError'
+    this.workspaceId = workspaceId
+  }
+}
+
+export function isWorkspaceAccessDeniedError(error: unknown): error is WorkspaceAccessDeniedError {
+  return error instanceof WorkspaceAccessDeniedError
+}
+
 export async function assertActiveWorkspaceAccess(
   workspaceId: string,
   userId: string
 ): Promise<WorkspaceAccess> {
   const access = await checkWorkspaceAccess(workspaceId, userId)
   if (!access.exists || !access.hasAccess) {
-    throw new Error(`Active workspace access denied: ${workspaceId}`)
+    throw new WorkspaceAccessDeniedError(workspaceId)
   }
   return access
 }