Sync alphalib 2025 12 29 (#273)

* Create playwright.mdc

* Update ai-chat.ts

Author: kvz

.cursor/rules/playwright.mdc

@@ -0,0 +1,11 @@
+---
+description: Playwright e2e guidelines distilled from PR #4601 feedback
+globs: _src/tests/**/*.pwtest.ts,playwright.config.ts
+alwaysApply: false
+---
+- Prefer user-centric locators: `getByRole`/`getByText` with accessible names; avoid `page.locator('body')`, `innerText()`, or raw CSS unless there is no accessible alternative.
+- Make positive assertions on expected UI/text instead of looping over regexes to assert absence.
+- Keep tests simple: no control-flow loops or extra variables for straightforward assertions.
+- Navigate with relative URLs (`page.goto('/path')`) by setting `baseURL` in `playwright.config.ts`; avoid stringing environment URLs in tests.
+- Stub or mock external/third‑party requests (Intercom, Sentry, etc.) and any auth/login endpoints to keep tests deterministic; return minimal valid JSON when the app expects data.
+- Each unexpected error should surface and fail the test.

src/alphalib/types/robots/ai-chat.ts

@@ -33,7 +33,8 @@ const imagePartSchema = z.object({
     z.string(),
     z.instanceof(Uint8Array),
     z.instanceof(ArrayBuffer),
-    z.instanceof(Buffer),
+    // Note: Buffer is not included here since it's Node.js-only and this code runs in browsers.
+    // Node.js Buffer extends Uint8Array, so Uint8Array validation handles Buffer values too.
     z.instanceof(URL),
   ]),
   mimeType: z.string().optional(),
@@ -45,7 +46,8 @@ const filePartSchema = z.object({
     z.string(),
     z.instanceof(Uint8Array),
     z.instanceof(ArrayBuffer),
-    z.instanceof(Buffer),
+    // Note: Buffer is not included here since it's Node.js-only and this code runs in browsers.
+    // Node.js Buffer extends Uint8Array, so Uint8Array validation handles Buffer values too.
     z.instanceof(URL),
   ]),
   mediaType: z.string(),
@@ -136,7 +138,7 @@ export const meta: RobotMetaInput = {
   trackOutputFileSize: true,
   isInternal: false,
   removeJobResultFilesFromDiskRightAfterStoringOnS3: false,
-  stage: 'ga',
+  stage: 'alpha',
 }
 
 export const vendorModelSchema = z