chore: replace prettier with oxfmt and enforce format:check in CI

.changeset/oxfmt-formatting.md

@@ -0,0 +1,7 @@
+---
+"@vercel/sandbox-mock": patch
+"@vercel/sandbox": patch
+"sandbox": patch
+---
+
+Format all JavaScript and TypeScript sources with [oxfmt](https://oxc.rs/docs/guide/usage/formatter) and enforce `pnpm run format:check` in CI, so pull requests no longer carry whitespace-only churn. No runtime behaviour changes.

.github/workflows/format.yml

@@ -0,0 +1,34 @@
+name: Format
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  format:
+    name: Check formatting
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repo
+        uses: actions/checkout@v4
+
+      - uses: pnpm/action-setup@v4
+        with:
+          run_install: false
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "24.16.0"
+          cache: "pnpm"
+
+      - run: pnpm install
+        shell: bash
+
+      - name: Check formatting
+        run: pnpm run format:check

.oxfmtrc.json

@@ -0,0 +1,20 @@
+{
+  "$schema": "./node_modules/oxfmt/configuration_schema.json",
+  "printWidth": 80,
+  "ignorePatterns": [
+    "**/dist/**",
+    "**/build/**",
+    "**/out/**",
+    "**/.next/**",
+    "**/.turbo/**",
+    "**/.vercel/**",
+    "**/*.json",
+    "**/*.jsonc",
+    "**/*.json5",
+    "**/*.md",
+    "**/*.mdx",
+    "**/*.yml",
+    "**/*.yaml",
+    "**/*.css"
+  ]
+}

CONTRIBUTING.md

@@ -1,5 +1,18 @@
 # Contributing
 
+## Formatting
+
+JavaScript and TypeScript are formatted with [oxfmt](https://oxc.rs/docs/guide/usage/formatter),
+configured in [`.oxfmtrc.json`](./.oxfmtrc.json). JSON and Markdown are still
+formatted with Prettier.
+
+- `pnpm run format` formats every JS/TS file in the repo.
+- `pnpm run format:check` reports files that are not formatted. CI runs this on
+  every pull request, so unformatted code fails the build.
+
+A `pre-commit` hook runs oxfmt over staged JS/TS files, so in practice you
+rarely need to run either command by hand.
+
 ## Running the tests
 
 NOTE: Running the tests creates actual sandboxes.

examples/ai-example/components/ui/badge.tsx

@@ -1,8 +1,8 @@
-import * as React from "react"
-import { Slot } from "@radix-ui/react-slot"
-import { cva, type VariantProps } from "class-variance-authority"
+import * as React from "react";
+import { Slot } from "@radix-ui/react-slot";
+import { cva, type VariantProps } from "class-variance-authority";
 
-import { cn } from "@/lib/utils"
+import { cn } from "@/lib/utils";
 
 const badgeVariants = cva(
   "inline-flex items-center justify-center rounded-md border px-2 py-0.5 text-xs font-medium w-fit whitespace-nowrap shrink-0 [&>svg]:size-3 gap-1 [&>svg]:pointer-events-none focus-visible:border-ring focus-visible:ring-ring/50 focus-visible:ring-[3px] aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive transition-[color,box-shadow] overflow-hidden",
@@ -22,8 +22,8 @@ const badgeVariants = cva(
     defaultVariants: {
       variant: "default",
     },
-  }
-)
+  },
+);
 
 function Badge({
   className,
@@ -32,15 +32,15 @@ function Badge({
   ...props
 }: React.ComponentProps<"span"> &
   VariantProps<typeof badgeVariants> & { asChild?: boolean }) {
-  const Comp = asChild ? Slot : "span"
+  const Comp = asChild ? Slot : "span";
 
   return (
     <Comp
       data-slot="badge"
       className={cn(badgeVariants({ variant }), className)}
       {...props}
     />
-  )
+  );
 }
 
-export { Badge, badgeVariants }
+export { Badge, badgeVariants };

examples/ai-example/components/ui/button.tsx

@@ -1,8 +1,8 @@
-import * as React from "react"
-import { Slot } from "@radix-ui/react-slot"
-import { cva, type VariantProps } from "class-variance-authority"
+import * as React from "react";
+import { Slot } from "@radix-ui/react-slot";
+import { cva, type VariantProps } from "class-variance-authority";
 
-import { cn } from "@/lib/utils"
+import { cn } from "@/lib/utils";
 
 const buttonVariants = cva(
   "inline-flex items-center justify-center gap-2 whitespace-nowrap rounded-md text-sm font-medium transition-all disabled:pointer-events-none disabled:opacity-50 [&_svg]:pointer-events-none [&_svg:not([class*='size-'])]:size-4 shrink-0 [&_svg]:shrink-0 outline-none focus-visible:border-ring focus-visible:ring-ring/50 focus-visible:ring-[3px] aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive",
@@ -32,8 +32,8 @@ const buttonVariants = cva(
       variant: "default",
       size: "default",
     },
-  }
-)
+  },
+);
 
 function Button({
   className,
@@ -43,17 +43,17 @@ function Button({
   ...props
 }: React.ComponentProps<"button"> &
   VariantProps<typeof buttonVariants> & {
-    asChild?: boolean
+    asChild?: boolean;
   }) {
-  const Comp = asChild ? Slot : "button"
+  const Comp = asChild ? Slot : "button";
 
   return (
     <Comp
       data-slot="button"
       className={cn(buttonVariants({ variant, size, className }))}
       {...props}
     />
-  )
+  );
 }
 
-export { Button, buttonVariants }
+export { Button, buttonVariants };

examples/ai-example/components/ui/card.tsx

@@ -1,18 +1,18 @@
-import * as React from "react"
+import * as React from "react";
 
-import { cn } from "@/lib/utils"
+import { cn } from "@/lib/utils";
 
 function Card({ className, ...props }: React.ComponentProps<"div">) {
   return (
     <div
       data-slot="card"
       className={cn(
         "bg-card text-card-foreground flex flex-col gap-6 rounded-xl border py-6 shadow-sm",
-        className
+        className,
       )}
       {...props}
     />
-  )
+  );
 }
 
 function CardHeader({ className, ...props }: React.ComponentProps<"div">) {
@@ -21,11 +21,11 @@ function CardHeader({ className, ...props }: React.ComponentProps<"div">) {
       data-slot="card-header"
       className={cn(
         "@container/card-header grid auto-rows-min grid-rows-[auto_auto] items-start gap-1.5 px-6 has-data-[slot=card-action]:grid-cols-[1fr_auto] [.border-b]:pb-6",
-        className
+        className,
       )}
       {...props}
     />
-  )
+  );
 }
 
 function CardTitle({ className, ...props }: React.ComponentProps<"div">) {
@@ -35,7 +35,7 @@ function CardTitle({ className, ...props }: React.ComponentProps<"div">) {
       className={cn("leading-none font-semibold", className)}
       {...props}
     />
-  )
+  );
 }
 
 function CardDescription({ className, ...props }: React.ComponentProps<"div">) {
@@ -45,7 +45,7 @@ function CardDescription({ className, ...props }: React.ComponentProps<"div">) {
       className={cn("text-muted-foreground text-sm", className)}
       {...props}
     />
-  )
+  );
 }
 
 function CardAction({ className, ...props }: React.ComponentProps<"div">) {
@@ -54,11 +54,11 @@ function CardAction({ className, ...props }: React.ComponentProps<"div">) {
       data-slot="card-action"
       className={cn(
         "col-start-2 row-span-2 row-start-1 self-start justify-self-end",
-        className
+        className,
       )}
       {...props}
     />
-  )
+  );
 }
 
 function CardContent({ className, ...props }: React.ComponentProps<"div">) {
@@ -68,7 +68,7 @@ function CardContent({ className, ...props }: React.ComponentProps<"div">) {
       className={cn("px-6", className)}
       {...props}
     />
-  )
+  );
 }
 
 function CardFooter({ className, ...props }: React.ComponentProps<"div">) {
@@ -78,7 +78,7 @@ function CardFooter({ className, ...props }: React.ComponentProps<"div">) {
       className={cn("flex items-center px-6 [.border-t]:pt-6", className)}
       {...props}
     />
-  )
+  );
 }
 
 export {
@@ -89,4 +89,4 @@ export {
   CardAction,
   CardDescription,
   CardContent,
-}
+};