fix: gate file-touching commands behind allowWrite and fs access

The `takeScreenshot` (write) and `upload` (read) commands resolved
client-controlled paths without checking the `allowWrite` permission gate
or Vite's `server.fs` access rules. Add vendored
`assertBrowserApiWrite`/`assertBrowserFileAccess` helpers and apply them so
these commands respect the same protections as the built-in file commands.

Co-authored-by: OpenCode (claude-opus-4-8) <noreply@opencode.ai>

Author: hi-ogawa

src/commands/permissions.ts

@@ -0,0 +1,29 @@
+import type { TestProject } from 'vitest/node'
+import { isFileLoadingAllowed } from 'vitest/node'
+
+const BACKSLASH_RE = /\\/g
+const REPEATED_SLASH_RE = /\/+/g
+
+function slash(path: string): string {
+  return path.replace(BACKSLASH_RE, '/').replace(REPEATED_SLASH_RE, '/')
+}
+
+export function assertBrowserFileAccess(project: TestProject, path: string): void {
+  const normalized = slash(path)
+  if (
+    !isFileLoadingAllowed(project.vite.config, normalized)
+    && !isFileLoadingAllowed(project.vitest.vite.config, normalized)
+  ) {
+    throw new Error(
+      `Access denied to "${path}". See Vite config documentation for "server.fs": https://vitejs.dev/config/server-options.html#server-fs-strict.`,
+    )
+  }
+}
+
+export function assertBrowserApiWrite(project: TestProject, path: string): void {
+  if (!project.config.browser.api.allowWrite || !project.vitest.config.api.allowWrite) {
+    throw new Error(
+      `Cannot modify file "${path}". File writing is disabled because the server is exposed to the internet, see https://vitest.dev/config/browser/api.`,
+    )
+  }
+}

src/commands/screenshot.ts

@@ -6,6 +6,7 @@ import { mkdir, rm } from 'node:fs/promises'
 import { normalize as platformNormalize } from 'node:path'
 import { resolveScreenshotPath } from '@vitest/browser'
 import { dirname, normalize, resolve } from 'pathe'
+import { assertBrowserApiWrite, assertBrowserFileAccess } from './permissions'
 
 interface ScreenshotCommandOptions extends Omit<ScreenshotOptions, 'element' | 'mask'> {
   element?: SerializedLocator
@@ -43,6 +44,9 @@ export async function takeScreenshot(
   if (options.save) {
     savePath = normalize(path)
 
+    assertBrowserApiWrite(context.project, savePath)
+    assertBrowserFileAccess(context.project, savePath)
+
     await mkdir(dirname(savePath), { recursive: true })
   }
 

src/commands/upload.ts

@@ -2,6 +2,7 @@ import type { SerializedLocator } from '@vitest/browser'
 import type { UserEventUploadOptions } from 'vitest/browser'
 import type { UserEventCommand } from './utils'
 import { resolve } from 'pathe'
+import { assertBrowserFileAccess } from './permissions'
 
 export const upload: UserEventCommand<(element: SerializedLocator, files: Array<string | {
   name: string
@@ -29,6 +30,7 @@ export const upload: UserEventCommand<(element: SerializedLocator, files: Array<
 
   for (const file of files) {
     const filepath = resolve(root, file as string)
+    assertBrowserFileAccess(context.project, filepath)
     const remoteFilePath = await context.browser.uploadFile(filepath)
     await element.addValue(remoteFilePath)
   }