fix(files): count the document body against the export limit

apps/sim/app/api/files/export/[id]/route.test.ts

@@ -4,6 +4,7 @@
 import { createMockRequest } from '@sim/testing'
 import JSZip from 'jszip'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { PayloadSizeLimitError } from '@/lib/core/utils/stream-limits'
 
 const {
   mockCheckAuth,
@@ -79,19 +80,6 @@ describe('markdown export bundling', () => {
     mockExtractEmbeddedImageIds.mockReturnValue([])
   })
 
-  it('rejects a document embedding more assets than an export may bundle', async () => {
-    mockExtractEmbeddedImageIds.mockReturnValue(
-      Array.from({ length: 501 }, (_, index) => `img-${index}`)
-    )
-
-    const response = await GET(request(), context)
-
-    expect(response.status).toBe(400)
-    expect((await response.json()).error).toContain('501')
-    // Rejected on the embed count alone: nothing was resolved or downloaded.
-    expect(mockGetFileMetadataById).toHaveBeenCalledTimes(1)
-  })
-
   it('rejects on declared asset bytes before downloading any of them', async () => {
     mockExtractEmbeddedImageIds.mockReturnValue(['a', 'b', 'c'])
     mockGetFileMetadataById.mockImplementation(async (id: string) =>
@@ -116,6 +104,39 @@ describe('markdown export bundling', () => {
     expect(mockDownloadFile).toHaveBeenCalledTimes(1)
   })
 
+  it('counts the document body against the export limit, not just its assets', async () => {
+    // Assets alone sit under the cap; the body is what carries the bundle over it.
+    mockExtractEmbeddedImageIds.mockReturnValue(['a'])
+    mockDownloadFile.mockResolvedValue(Buffer.alloc(250 * MB))
+
+    const response = await GET(request(), context)
+
+    expect(response.status).toBe(400)
+    expect((await response.json()).error).toContain('document and its embedded files')
+  })
+
+  it('caps the document body read rather than loading it unbounded', async () => {
+    mockExtractEmbeddedImageIds.mockReturnValue([])
+
+    await GET(request(), context)
+
+    const bodyCall = mockDownloadFile.mock.calls.find(([options]) => options.key.endsWith('doc.md'))
+    expect(bodyCall?.[0].maxBytes).toBe(250 * MB)
+  })
+
+  it('reports an oversized body as a size rejection, not a server error', async () => {
+    mockExtractEmbeddedImageIds.mockReturnValue([])
+    mockDownloadFile.mockRejectedValue(
+      new PayloadSizeLimitError({ label: 'storage file download', maxBytes: 1 })
+    )
+
+    const response = await GET(request(), context)
+
+    // The cap exists to produce a clear limit message; a 500 would hide it.
+    expect(response.status).toBe(400)
+    expect((await response.json()).error).toContain('export limit')
+  })
+
   it('caps each asset download rather than trusting its declared size', async () => {
     mockExtractEmbeddedImageIds.mockReturnValue(['a'])
 

apps/sim/app/api/files/export/[id]/route.ts

@@ -10,6 +10,7 @@ import { parseRequest } from '@/lib/api/server'
 import { checkSessionOrInternalAuth } from '@/lib/auth/hybrid'
 import { extractEmbeddedImageIds } from '@/lib/copilot/tools/server/files/embedded-image-refs'
 import { MATERIALIZE_CONCURRENCY, mapWithConcurrency } from '@/lib/core/utils/concurrency'
+import { isPayloadSizeLimitError } from '@/lib/core/utils/stream-limits'
 import { withRouteHandler } from '@/lib/core/utils/with-route-handler'
 import { captureServerEvent } from '@/lib/posthog/server'
 import type { StorageContext } from '@/lib/uploads/config'
@@ -23,16 +24,14 @@ import { encodeFilenameForHeader } from '@/app/api/files/utils'
 const logger = createLogger('FilesExportAPI')
 
 /**
- * Bundling caps. The embed list comes from scanning the document body, so its length
- * and the bytes behind it are whatever the author put there — without these the export
- * would materialize an unbounded number of unbounded assets in one request.
+ * Byte ceilings for a bundled export. The bytes behind an embed list are whatever the
+ * author put there, so without these the export would materialize unbounded assets in
+ * one request. They match the bulk-download route, so the two export surfaces reject at
+ * the same size.
  *
- * The byte ceilings are the real bound and match the bulk-download route, so the two
- * export surfaces reject at the same size. The count is only a guard on the metadata
- * lookups that precede the byte check, so it sits far above any hand-authored document
- * rather than at a number a screenshot-heavy doc could plausibly reach.
+ * There is deliberately no count cap here: `extractEmbeddedFileRefs` already stops at
+ * `MAX_EMBEDDED_IMAGES`, so the list this route receives is bounded before it arrives.
  */
-const MAX_EXPORT_ASSETS = 500
 const MAX_EXPORT_ASSET_BYTES = 25 * 1024 * 1024
 const MAX_EXPORT_TOTAL_BYTES = 250 * 1024 * 1024
 
@@ -128,10 +127,26 @@ export const GET = withRouteHandler(
       return NextResponse.redirect(new URL(servePath, request.url), { status: 302 })
     }
 
-    const mdBuffer = await downloadFile({
-      key: record.key,
-      context: record.context as StorageContext,
-    })
+    // Capped like everything else in the bundle: the document body is usually the
+    // largest single entry, so leaving it unbounded left the export limit unenforced
+    // against the one item most able to exceed it. A body that alone exceeds the limit
+    // is a size rejection, so it reports as one rather than as a server error.
+    let mdBuffer: Buffer
+    try {
+      mdBuffer = await downloadFile({
+        key: record.key,
+        context: record.context as StorageContext,
+        maxBytes: MAX_EXPORT_TOTAL_BYTES,
+      })
+    } catch (error) {
+      if (!isPayloadSizeLimitError(error)) throw error
+      return NextResponse.json(
+        {
+          error: `This document exceeds the ${formatFileSize(MAX_EXPORT_TOTAL_BYTES)} export limit.`,
+        },
+        { status: 400 }
+      )
+    }
     let mdContent = mdBuffer.toString('utf-8')
 
     const imageIds = extractEmbeddedImageIds(mdContent)
@@ -152,15 +167,6 @@ export const GET = withRouteHandler(
       })
     }
 
-    if (imageIds.length > MAX_EXPORT_ASSETS) {
-      return NextResponse.json(
-        {
-          error: `This document embeds ${imageIds.length} files, more than the ${MAX_EXPORT_ASSETS} an export can bundle.`,
-        },
-        { status: 400 }
-      )
-    }
-
     // Metadata first: declared sizes bound the download before a byte is read, and the
     // authorization check costs nothing to run here.
     const assetTargets = (
@@ -180,11 +186,14 @@ export const GET = withRouteHandler(
       })
     ).filter((target): target is NonNullable<typeof target> => target !== null)
 
-    const declaredAssetBytes = assetTargets.reduce((sum, target) => sum + target.record.size, 0)
-    if (declaredAssetBytes > MAX_EXPORT_TOTAL_BYTES) {
+    // The body counts against the same budget as its assets — the zip holds both, so a
+    // limit that measured only the attachments would not describe the archive produced.
+    const bundleBytes =
+      mdBuffer.length + assetTargets.reduce((sum, target) => sum + target.record.size, 0)
+    if (bundleBytes > MAX_EXPORT_TOTAL_BYTES) {
       return NextResponse.json(
         {
-          error: `Embedded files total ${formatFileSize(declaredAssetBytes)}, which exceeds the ${formatFileSize(MAX_EXPORT_TOTAL_BYTES)} export limit.`,
+          error: `This document and its embedded files total ${formatFileSize(bundleBytes)}, which exceeds the ${formatFileSize(MAX_EXPORT_TOTAL_BYTES)} export limit.`,
         },
         { status: 400 }
       )

apps/sim/app/api/v1/files/[fileId]/route.test.ts

@@ -0,0 +1,135 @@
+/**
+ * @vitest-environment node
+ */
+import { createMockRequest } from '@sim/testing'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+const {
+  mockCheckRateLimit,
+  mockValidateWorkspaceAccess,
+  mockGetWorkspaceFile,
+  mockFetchServableWorkspaceFileBuffer,
+} = vi.hoisted(() => ({
+  mockCheckRateLimit: vi.fn(),
+  mockValidateWorkspaceAccess: vi.fn(),
+  mockGetWorkspaceFile: vi.fn(),
+  mockFetchServableWorkspaceFileBuffer: vi.fn(),
+}))
+
+vi.mock('@/app/api/v1/middleware', () => ({
+  checkRateLimit: mockCheckRateLimit,
+  createRateLimitResponse: () => new Response('rate limited', { status: 429 }),
+  validateWorkspaceAccess: mockValidateWorkspaceAccess,
+}))
+vi.mock('@/lib/uploads/contexts/workspace', () => ({
+  getWorkspaceFile: mockGetWorkspaceFile,
+  fetchServableWorkspaceFileBuffer: mockFetchServableWorkspaceFileBuffer,
+}))
+vi.mock('@/lib/workspace-files/orchestration', () => ({
+  performDeleteWorkspaceFileItems: vi.fn(),
+}))
+vi.mock('@sim/audit', () => ({
+  recordAudit: vi.fn(),
+  AuditAction: { FILE_DOWNLOADED: 'file.downloaded', FILE_DELETED: 'file.deleted' },
+  AuditResourceType: { FILE: 'file' },
+}))
+vi.mock('@/lib/posthog/server', () => ({ captureServerEvent: vi.fn() }))
+
+import { DocCompileUserError } from '@/lib/copilot/tools/server/files/doc-compile'
+import { GET } from '@/app/api/v1/files/[fileId]/route'
+
+const WORKSPACE_ID = 'ws-1'
+const FILE_ID = 'file-1'
+const context = { params: Promise.resolve({ fileId: FILE_ID }) }
+
+const DOCX_MIME = 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
+
+function request() {
+  return createMockRequest(
+    'GET',
+    undefined,
+    {},
+    `http://localhost:3000/api/v1/files/${FILE_ID}?workspaceId=${WORKSPACE_ID}`
+  )
+}
+
+/** A generated document: the name carries the target extension, the type the source. */
+function generatedDocument(name = 'report.docx') {
+  return {
+    id: FILE_ID,
+    workspaceId: WORKSPACE_ID,
+    name,
+    key: `workspace/${WORKSPACE_ID}/${FILE_ID}`,
+    path: `/serve/${FILE_ID}`,
+    size: 6_242,
+    type: 'text/x-docxjs',
+    uploadedBy: 'user-1',
+    uploadedAt: new Date('2026-01-01'),
+    updatedAt: new Date('2026-01-01'),
+  }
+}
+
+describe('v1 file download', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    mockCheckRateLimit.mockResolvedValue({ allowed: true, userId: 'user-1' })
+    mockValidateWorkspaceAccess.mockResolvedValue(null)
+    mockGetWorkspaceFile.mockResolvedValue(generatedDocument())
+    mockFetchServableWorkspaceFileBuffer.mockResolvedValue({
+      buffer: Buffer.from('PKrendered'),
+      contentType: DOCX_MIME,
+    })
+  })
+
+  it('serves the rendered bytes and the rendered content type', async () => {
+    const response = await GET(request(), context)
+
+    expect(response.status).toBe(200)
+    // Not the record's `text/x-docxjs`, which describes the stored source.
+    expect(response.headers.get('Content-Type')).toBe(DOCX_MIME)
+    expect(Buffer.from(await response.arrayBuffer()).toString()).toContain('rendered')
+  })
+
+  it('names the download with an extension matching the served content type', async () => {
+    // The renderer picks its output format from the file name, so the two cannot
+    // disagree: a `.docx` renders to a docx. This pins that invariant.
+    const response = await GET(request(), context)
+
+    const disposition = response.headers.get('Content-Disposition') ?? ''
+    expect(disposition).toContain('report.docx')
+    expect(response.headers.get('Content-Type')).toBe(DOCX_MIME)
+  })
+
+  it('reports Content-Length from the rendered bytes, not the declared source size', async () => {
+    const rendered = Buffer.alloc(50_000)
+    mockFetchServableWorkspaceFileBuffer.mockResolvedValue({
+      buffer: rendered,
+      contentType: DOCX_MIME,
+    })
+
+    const response = await GET(request(), context)
+
+    expect(response.headers.get('Content-Length')).toBe(String(rendered.length))
+  })
+
+  it('returns a retryable 409 while the artifact is still compiling', async () => {
+    mockFetchServableWorkspaceFileBuffer.mockRejectedValue(
+      new DocCompileUserError('Document is still being generated')
+    )
+
+    const response = await GET(request(), context)
+
+    // A 500 would give the caller no reason to try again.
+    expect(response.status).toBe(409)
+    expect((await response.json()).error).toContain('still being generated')
+  })
+
+  it('404s a file that does not exist', async () => {
+    mockGetWorkspaceFile.mockResolvedValue(null)
+
+    const response = await GET(request(), context)
+
+    expect(response.status).toBe(404)
+    expect(mockFetchServableWorkspaceFileBuffer).not.toHaveBeenCalled()
+  })
+})