From fb74cadd3747296f18cc97c12ec64b2db0b1a894 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 24 Sep 2026 14:54:41 +0000
Subject: [PATCH 1/6] Add Biome for linting and formatting

Co-authored-by: Anirudh Kamath <kamath@users.noreply.github.com>
---
 biome.json     | 42 ++++++++++++++++++++++
 package.json   | 10 ++++--
 pnpm-lock.yaml | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 144 insertions(+), 3 deletions(-)
 create mode 100644 biome.json

diff --git a/biome.json b/biome.json
new file mode 100644
index 0000000..f056836
--- /dev/null
+++ b/biome.json
@@ -0,0 +1,42 @@
+{
+  "$schema": "https://biomejs.dev/schemas/2.5.14/schema.json",
+  "vcs": {
+    "enabled": true,
+    "clientKind": "git",
+    "useIgnoreFile": true
+  },
+  "files": {
+    "ignoreUnknown": false,
+    "includes": ["**", "!**/worker-configuration.d.ts"]
+  },
+  "formatter": {
+    "enabled": true,
+    "indentStyle": "space",
+    "indentWidth": 2,
+    "lineWidth": 100
+  },
+  "linter": {
+    "enabled": true,
+    "rules": {
+      "preset": "recommended"
+    }
+  },
+  "javascript": {
+    "formatter": {
+      "quoteStyle": "double"
+    }
+  },
+  "css": {
+    "parser": {
+      "tailwindDirectives": true
+    }
+  },
+  "assist": {
+    "enabled": true,
+    "actions": {
+      "source": {
+        "organizeImports": "on"
+      }
+    }
+  }
+}
diff --git a/package.json b/package.json
index 78ef0e8..c529182 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,10 @@
   "packageManager": "pnpm@11.10.0",
   "scripts": {
     "build": "pnpm -r build",
-    "check": "pnpm -r check",
+    "check": "biome check . && pnpm -r check",
+    "lint": "biome check .",
+    "lint:fix": "biome check --write .",
+    "format": "biome format --write .",
     "test": "pnpm -r --if-present test",
     "test:e2e": "pnpm --filter @browse-code-mode/mcp-server test:e2e",
     "dev": "node scripts/dev.mjs",
@@ -21,7 +24,8 @@
     "example": "node scripts/example.mjs"
   },
   "devDependencies": {
-    "typescript": "^5.9.3",
-    "@types/node": "^22.19.0"
+    "@biomejs/biome": "2.5.14",
+    "@types/node": "^22.19.0",
+    "typescript": "^5.9.3"
   }
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 23fa8d8..8432ba8 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -8,6 +8,9 @@ importers:
 
   .:
     devDependencies:
+      '@biomejs/biome':
+        specifier: 2.5.14
+        version: 2.5.14
       '@types/node':
         specifier: ^22.19.0
         version: 22.20.4
@@ -364,6 +367,63 @@ packages:
     resolution: {integrity: sha512-Vj1jF3cPfxg7OAfoI7QnVKLoILlm2JF9pnVHrX8qx7AHMiYWT+NDAA7jChlNgRS4WTLc/fD1lXLmPixluj+3Gg==}
     engines: {node: '>=6.9.0'}
 
+  '@biomejs/biome@2.5.14':
+    resolution: {integrity: sha512-0FabLIjd4M/dm8VFI86RMaLLdgepzbdfiAL2R8cr7V81OYYrP1w7Z73KfAwPK5h9SrEBXTzNG2y+mBwPo9xRnw==}
+    engines: {node: '>=14.21.3'}
+    hasBin: true
+
+  '@biomejs/cli-darwin-arm64@2.5.14':
+    resolution: {integrity: sha512-UnzaXO65L4tsZimFITFP2M121GyhDcWFrT3pL5ZJ5U4XcS/0L5VHYytVohdCf/gnDUFHgl2I9xnt5bV/J1kxHQ==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [darwin]
+
+  '@biomejs/cli-darwin-x64@2.5.14':
+    resolution: {integrity: sha512-kiy8qA16K93J7uvFfWi4LgjqDpnRKyePAna6A0Y4jxyUga35SYpIZ2cNWlhy0lsfgqRenCpfymnJWEZ6mgpRgA==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [darwin]
+
+  '@biomejs/cli-linux-arm64-musl@2.5.14':
+    resolution: {integrity: sha512-SJ9PrZkBnnH9dHJDnxk34vKs0GB2dbsioaft6/hPhWJ7AHpwYH83Isnhj0FSRpFkGgpVfJ1lds23ApB2czUDLQ==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [linux]
+    libc: [musl]
+
+  '@biomejs/cli-linux-arm64@2.5.14':
+    resolution: {integrity: sha512-vO/9BaU1n30CiFNLx49gMTMtbCAAqlo/EqFoG0BU3deQInTbJrmXSmTQ9e3FoDZIKQnvSLDVNL4lx1ci7y1T1Q==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [linux]
+    libc: [glibc]
+
+  '@biomejs/cli-linux-x64-musl@2.5.14':
+    resolution: {integrity: sha512-2kI5PrMgW5dcEZYrstLPmUmCwkUwZY39rP4BN93Vxbwcs2O57LDQOktUZZYPvvspN5i0mhGr3TJtF5sU26NUWg==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [linux]
+    libc: [musl]
+
+  '@biomejs/cli-linux-x64@2.5.14':
+    resolution: {integrity: sha512-VHZRa7CCQBUWKxNwUvHJeuW03WFRgN5NWO//SDGOitc9QIeNyfA42V9zlKm+x82xFSG9Bzi5fi+hbhm9anO8yA==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [linux]
+    libc: [glibc]
+
+  '@biomejs/cli-win32-arm64@2.5.14':
+    resolution: {integrity: sha512-pHgAFffmZtaYoxavEsWEYNvcA7NwOIjLyqw2HXyLbt16xYryX0L4fMV2u0G9ag6LNYPIoqWaWqzUcnc6rLGGXg==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [win32]
+
+  '@biomejs/cli-win32-x64@2.5.14':
+    resolution: {integrity: sha512-oJWmBhoHsnhUKIke+0gXDX0mltJrWHA1UyHsrTlXwX0TL64ilVZAo+TYZm97baecV0esBdpzy3k96q+09JaZUQ==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [win32]
+
   '@cloudflare/kv-asset-handler@0.5.0':
     resolution: {integrity: sha512-jxQYkj8dSIzc0cD6cMMNdOc1UVjqSqu8BZdor5s8cGjW2I8BjODt/kWPVdY+u9zj3ms75Q5qaZgnxUad83+eAg==}
     engines: {node: '>=22.0.0'}
@@ -3368,6 +3428,41 @@ snapshots:
       '@babel/helper-string-parser': 7.29.7
       '@babel/helper-validator-identifier': 7.29.7
 
+  '@biomejs/biome@2.5.14':
+    optionalDependencies:
+      '@biomejs/cli-darwin-arm64': 2.5.14
+      '@biomejs/cli-darwin-x64': 2.5.14
+      '@biomejs/cli-linux-arm64': 2.5.14
+      '@biomejs/cli-linux-arm64-musl': 2.5.14
+      '@biomejs/cli-linux-x64': 2.5.14
+      '@biomejs/cli-linux-x64-musl': 2.5.14
+      '@biomejs/cli-win32-arm64': 2.5.14
+      '@biomejs/cli-win32-x64': 2.5.14
+
+  '@biomejs/cli-darwin-arm64@2.5.14':
+    optional: true
+
+  '@biomejs/cli-darwin-x64@2.5.14':
+    optional: true
+
+  '@biomejs/cli-linux-arm64-musl@2.5.14':
+    optional: true
+
+  '@biomejs/cli-linux-arm64@2.5.14':
+    optional: true
+
+  '@biomejs/cli-linux-x64-musl@2.5.14':
+    optional: true
+
+  '@biomejs/cli-linux-x64@2.5.14':
+    optional: true
+
+  '@biomejs/cli-win32-arm64@2.5.14':
+    optional: true
+
+  '@biomejs/cli-win32-x64@2.5.14':
+    optional: true
+
   '@cloudflare/kv-asset-handler@0.5.0': {}
 
   '@cloudflare/unenv-preset@2.16.1(unenv@2.0.0-rc.24)(workerd@1.20260921.1)':

From 21e0974fd02441397c87ffd1d7992f5eab89c70c Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 24 Sep 2026 14:54:42 +0000
Subject: [PATCH 2/6] Apply Biome formatting and safe lint fixes

Co-authored-by: Anirudh Kamath <kamath@users.noreply.github.com>
---
 README.md                                     |   4 +
 apps/web/src/lib/browser-api.ts               |  26 ++-
 apps/web/src/lib/browser-app.ts               |  10 +-
 apps/web/src/lib/mcp.ts                       |   5 +-
 apps/web/src/routes/__root.tsx                |   9 +-
 apps/web/src/routes/api.chat.ts               |  12 +-
 apps/web/src/routes/index.tsx                 |  59 +++---
 apps/web/src/styles.css                       |  51 ++++-
 apps/web/tests/browser-api.test.ts            |  61 ++++--
 apps/web/vite.config.ts                       |  39 ++--
 examples/01-hello-world/index.ts              |   4 +-
 examples/02-mcp-server/index.ts               |  10 +-
 packages/mcp-server/api/index.ts              |   4 +-
 packages/mcp-server/src/app.ts                |  50 +++--
 packages/mcp-server/src/browse/cdp.ts         |   3 +-
 packages/mcp-server/src/browse/commands.ts    |  33 +--
 packages/mcp-server/src/browse/driver.ts      |  45 +++-
 packages/mcp-server/src/browse/dts.ts         |  17 +-
 .../mcp-server/src/browse/host-functions.ts   |  10 +-
 packages/mcp-server/src/browse/page.ts        | 130 ++++++------
 packages/mcp-server/src/browse/provider.ts    |   4 +-
 packages/mcp-server/src/browse/providers.ts   |  27 +--
 packages/mcp-server/src/browse/transport.ts   |  31 +--
 packages/mcp-server/src/core.ts               |  38 ++--
 packages/mcp-server/src/index.ts              |  33 ++-
 packages/mcp-server/src/mcp/server.ts         |   7 +-
 packages/mcp-server/src/node/local-browser.ts |  39 ++--
 packages/mcp-server/src/runtime-bundled.ts    |  21 +-
 packages/mcp-server/src/runtime.ts            |   2 +-
 packages/mcp-server/src/sandbox/runner.ts     | 150 ++++++--------
 packages/mcp-server/src/worker.ts             |  23 +-
 packages/mcp-server/tests/browser.e2e.test.ts |   6 +-
 packages/mcp-server/tests/commands.test.ts    |  16 +-
 packages/mcp-server/tests/frames.e2e.test.ts  |  38 +++-
 packages/mcp-server/tests/lifecycle.test.ts   |  33 +--
 packages/mcp-server/tests/mcp.test.ts         |  24 ++-
 packages/mcp-server/tests/runtime.e2e.test.ts | 196 ++++++++----------
 packages/mcp-server/tests/sandbox.test.ts     |  13 +-
 packages/mcp-server/tsconfig.json             |  12 +-
 packages/tools/package.json                   |   8 +-
 packages/tools/src/ai-sdk.ts                  |  16 +-
 packages/tools/src/browser.ts                 |   2 +-
 packages/tools/src/index.ts                   |  43 ++--
 packages/tools/src/mastra.ts                  |  20 +-
 packages/tools/tests/browser.test.ts          |  12 +-
 packages/tools/tests/tools.test.ts            |  63 ++++--
 packages/tools/tsconfig.json                  |  12 +-
 scripts/chrome.mjs                            |   4 +-
 scripts/dev.mjs                               |  50 ++---
 49 files changed, 804 insertions(+), 721 deletions(-)

diff --git a/README.md b/README.md
index 8785057..fb864ca 100644
--- a/README.md
+++ b/README.md
@@ -268,6 +268,10 @@ pnpm --filter @browse-code-mode/mcp-server test:worker
 pnpm test:e2e  # existing browser on BROWSE_CDP_URL or port 9222
 ```
 
+`pnpm check` runs [Biome](https://biomejs.dev) (lint, formatting, import order)
+before type-checking every package. `pnpm lint:fix` applies Biome's safe fixes
+and formatting; `pnpm format` only formats.
+
 The runtime suites start an isolated Chrome and exercise real MCP execution,
 TypeScript, snapshot-ref clicks, loop interruption, screenshots, and lifecycle
 cleanup against Node and local workerd. They shut down their test processes.
diff --git a/apps/web/src/lib/browser-api.ts b/apps/web/src/lib/browser-api.ts
index 4837842..16584b4 100644
--- a/apps/web/src/lib/browser-api.ts
+++ b/apps/web/src/lib/browser-api.ts
@@ -1,12 +1,15 @@
-import { mcpHeaders } from "./env.ts";
 import { fetchBrowserApp } from "./browser-app.ts";
+import { mcpHeaders } from "./env.ts";
 
 /** Browser API calls are bounded; navigation/HMR cancellation is not a 500. */
-export async function proxyBrowserRequest(request: Request, path: "/browser" | "/screen", dispatch = fetchBrowserApp): Promise<Response> {
+export async function proxyBrowserRequest(
+  request: Request,
+  path: "/browser" | "/screen",
+  dispatch = fetchBrowserApp,
+): Promise<Response> {
   try {
-    const body = path === "/screen" || request.method === "DELETE"
-      ? await request.text()
-      : undefined;
+    const body =
+      path === "/screen" || request.method === "DELETE" ? await request.text() : undefined;
     const response = await dispatch(new URL(path, "http://browse.internal"), {
       method: request.method,
       headers: { ...mcpHeaders(), "content-type": "application/json" },
@@ -26,10 +29,13 @@ export async function proxyBrowserRequest(request: Request, path: "/browser" | "
   } catch (error) {
     if (request.signal.aborted) return new Response(null, { status: 499 });
     const timedOut = error instanceof Error && error.name === "TimeoutError";
-    return Response.json({
-      error: timedOut
-        ? "The browser service took too long to respond. Try again."
-        : "Cannot reach the browser service. Make sure pnpm dev is running, then try again.",
-    }, { status: timedOut ? 504 : 502 });
+    return Response.json(
+      {
+        error: timedOut
+          ? "The browser service took too long to respond. Try again."
+          : "Cannot reach the browser service. Make sure pnpm dev is running, then try again.",
+      },
+      { status: timedOut ? 504 : 502 },
+    );
   }
 }
diff --git a/apps/web/src/lib/browser-app.ts b/apps/web/src/lib/browser-app.ts
index 877e9d0..5c06fdc 100644
--- a/apps/web/src/lib/browser-app.ts
+++ b/apps/web/src/lib/browser-app.ts
@@ -1,9 +1,13 @@
 import { createConfiguredApp } from "@browse-code-mode/mcp-server/runtime";
 
 /** Request-local Hono app; no listener, loopback HTTP, or stored browser session. */
-export async function fetchBrowserApp(input: RequestInfo | URL, init?: RequestInit): Promise<Response> {
-  return createConfiguredApp({ ...process.env, MCP_ENDPOINT: "/mcp" })
-    .fetch(new Request(input, init));
+export async function fetchBrowserApp(
+  input: RequestInfo | URL,
+  init?: RequestInit,
+): Promise<Response> {
+  return createConfiguredApp({ ...process.env, MCP_ENDPOINT: "/mcp" }).fetch(
+    new Request(input, init),
+  );
 }
 
 /** Mount the complete Hono router beneath /api/browse. */
diff --git a/apps/web/src/lib/mcp.ts b/apps/web/src/lib/mcp.ts
index 25b3c4a..233c3a4 100644
--- a/apps/web/src/lib/mcp.ts
+++ b/apps/web/src/lib/mcp.ts
@@ -8,10 +8,9 @@
 import { Client } from "@modelcontextprotocol/sdk/client/index.js";
 import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
 import type { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
-import { dynamicTool, jsonSchema, type JSONSchema7, type ToolSet } from "ai";
-
-import { mcpHeaders } from "./env.ts";
+import { dynamicTool, type JSONSchema7, jsonSchema, type ToolSet } from "ai";
 import { fetchBrowserApp } from "./browser-app.ts";
+import { mcpHeaders } from "./env.ts";
 
 export interface McpSession {
   tools: ToolSet;
diff --git a/apps/web/src/routes/__root.tsx b/apps/web/src/routes/__root.tsx
index 873fe36..f07023a 100644
--- a/apps/web/src/routes/__root.tsx
+++ b/apps/web/src/routes/__root.tsx
@@ -1,4 +1,4 @@
-import { HeadContent, Outlet, Scripts, createRootRoute } from "@tanstack/react-router";
+import { createRootRoute, HeadContent, Outlet, Scripts } from "@tanstack/react-router";
 
 import styles from "../styles.css?url";
 
@@ -12,7 +12,12 @@ export const Route = createRootRoute({
     links: [{ rel: "stylesheet", href: styles }],
   }),
   component: RootDocument,
-  notFoundComponent: () => <main><h1>Page not found</h1><a href="/">Return to browser</a></main>,
+  notFoundComponent: () => (
+    <main>
+      <h1>Page not found</h1>
+      <a href="/">Return to browser</a>
+    </main>
+  ),
 });
 
 function RootDocument() {
diff --git a/apps/web/src/routes/api.chat.ts b/apps/web/src/routes/api.chat.ts
index e0aded6..150f084 100644
--- a/apps/web/src/routes/api.chat.ts
+++ b/apps/web/src/routes/api.chat.ts
@@ -1,11 +1,6 @@
 import { anthropic } from "@ai-sdk/anthropic";
 import { createFileRoute } from "@tanstack/react-router";
-import {
-  convertToModelMessages,
-  stepCountIs,
-  streamText,
-  type UIMessage,
-} from "ai";
+import { convertToModelMessages, stepCountIs, streamText, type UIMessage } from "ai";
 
 import { env } from "../lib/env.ts";
 import { openMcpSession } from "../lib/mcp.ts";
@@ -40,10 +35,7 @@ export const Route = createFileRoute("/api/chat")({
           cdpUrl?: string;
         };
         if (!cdpUrl || typeof cdpUrl !== "string")
-          return Response.json(
-            { error: "Start a browser first." },
-            { status: 400 },
-          );
+          return Response.json({ error: "Start a browser first." }, { status: 400 });
 
         let session;
         try {
diff --git a/apps/web/src/routes/index.tsx b/apps/web/src/routes/index.tsx
index e78492e..6274f5b 100644
--- a/apps/web/src/routes/index.tsx
+++ b/apps/web/src/routes/index.tsx
@@ -16,7 +16,7 @@ interface BrowserHandle {
 }
 
 async function responseError(response: Response): Promise<string> {
-  const body = await response.json().catch(() => null) as { error?: string } | null;
+  const body = (await response.json().catch(() => null)) as { error?: string } | null;
   return body?.error ?? `Browser request failed (HTTP ${response.status}).`;
 }
 
@@ -47,7 +47,9 @@ function Home() {
       try {
         if (next) sessionStorage.setItem("browse.browser", JSON.stringify(next));
         else sessionStorage.removeItem("browse.browser");
-      } catch { /* A blocked storage API must not prevent using the browser. */ }
+      } catch {
+        /* A blocked storage API must not prevent using the browser. */
+      }
     } catch (error) {
       setError(error instanceof Error ? error.message : String(error));
     } finally {
@@ -56,28 +58,31 @@ function Home() {
   };
   return (
     <div className="split">
-      <div
-        className="viewport"
-        style={{ display: "flex", flexDirection: "column" }}
-      >
+      <div className="viewport" style={{ display: "flex", flexDirection: "column" }}>
         <div style={{ padding: 12 }}>
           <button onClick={() => void lifecycle()} disabled={busy}>
             {busy ? "Working…" : browser ? "Stop browser" : "Start browser"}
           </button>
-          {browser ? <span role="status" style={{ marginLeft: 12 }}>Browser connected</span> : null}
-          {error ? <div className="error" role="alert">{error}</div> : null}
+          {browser ? (
+            <span role="status" style={{ marginLeft: 12 }}>
+              Browser connected
+            </span>
+          ) : null}
+          {error ? (
+            <div className="error" role="alert">
+              {error}
+            </div>
+          ) : null}
         </div>
         {browser ? (
           <LiveView browser={browser} />
         ) : (
-          <div className="viewport-empty" style={{ position: "static", flex: 1 }}>Start a browser to begin.</div>
+          <div className="viewport-empty" style={{ position: "static", flex: 1 }}>
+            Start a browser to begin.
+          </div>
         )}
       </div>
-      {browser ? (
-        <Chat key={browser.cdpUrl} cdpUrl={browser.cdpUrl} />
-      ) : (
-        <div className="chat" />
-      )}
+      {browser ? <Chat key={browser.cdpUrl} cdpUrl={browser.cdpUrl} /> : <div className="chat" />}
     </div>
   );
 }
@@ -154,9 +159,19 @@ function LiveView({ browser }: { browser: BrowserHandle }) {
       {src ? (
         <img className="frame" src={src} alt="" />
       ) : (
-        <div className="viewport-empty">{error ? "Browser preview unavailable" : "Waiting for the browser…"}</div>
+        <div className="viewport-empty">
+          {error ? "Browser preview unavailable" : "Waiting for the browser…"}
+        </div>
       )}
-      {error ? <div className="error" role="alert" style={{ position: "absolute", bottom: 16, left: 16, right: 16 }}>{error} Retrying…</div> : null}
+      {error ? (
+        <div
+          className="error"
+          role="alert"
+          style={{ position: "absolute", bottom: 16, left: 16, right: 16 }}
+        >
+          {error} Retrying…
+        </div>
+      ) : null}
     </div>
   );
 }
@@ -207,11 +222,7 @@ function Chat({ cdpUrl }: { cdpUrl: string }) {
           placeholder="Ask the browser to do something"
           rows={1}
         />
-        <button
-          type="button"
-          onClick={submit}
-          disabled={busy || input.trim().length === 0}
-        >
+        <button type="button" onClick={submit} disabled={busy || input.trim().length === 0}>
           Send
         </button>
       </div>
@@ -261,8 +272,7 @@ interface ToolCallView {
  * a tool-specific part type that only exists for statically declared tools.
  */
 function asToolCall(part: UIMessage["parts"][number]): ToolCallView | null {
-  if (part.type !== "dynamic-tool" && !part.type.startsWith("tool-"))
-    return null;
+  if (part.type !== "dynamic-tool" && !part.type.startsWith("tool-")) return null;
   const record = part as unknown as {
     type: string;
     toolName?: string;
@@ -284,8 +294,7 @@ function ToolCall({ call }: { call: ToolCallView }) {
   const code = codeOf(call.input);
   const output = call.errorText ?? textOf(call.output);
   const failed = Boolean(call.errorText) || call.state === "output-error";
-  const running =
-    call.state === "input-streaming" || call.state === "input-available";
+  const running = call.state === "input-streaming" || call.state === "input-available";
 
   return (
     <details
diff --git a/apps/web/src/styles.css b/apps/web/src/styles.css
index 75669fe..ff96444 100644
--- a/apps/web/src/styles.css
+++ b/apps/web/src/styles.css
@@ -18,9 +18,13 @@
   --error: #ff6b6b;
 }
 
-* { box-sizing: border-box; }
+* {
+  box-sizing: border-box;
+}
 
-html, body, #app {
+html,
+body,
+#app {
   height: 100%;
   margin: 0;
   /* Only the message list scrolls. Without this a wide code block in a tool
@@ -31,7 +35,12 @@ html, body, #app {
 body {
   background: var(--bg);
   color: var(--text);
-  font: 14px/1.5 ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
+  font:
+    14px / 1.5 ui-sans-serif,
+    system-ui,
+    -apple-system,
+    "Segoe UI",
+    sans-serif;
 }
 
 .split {
@@ -92,8 +101,15 @@ body {
   gap: 14px;
 }
 
-.msg { display: flex; flex-direction: column; gap: 8px; min-width: 0; }
-.msg-user { align-items: flex-end; }
+.msg {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  min-width: 0;
+}
+.msg-user {
+  align-items: flex-end;
+}
 
 .bubble {
   max-width: 92%;
@@ -103,8 +119,12 @@ body {
   overflow-wrap: anywhere;
 }
 
-.msg-user .bubble { background: #1e2a3d; }
-.msg-assistant .bubble { background: #17171a; }
+.msg-user .bubble {
+  background: #1e2a3d;
+}
+.msg-assistant .bubble {
+  background: #17171a;
+}
 
 /* Streamdown emits real block elements, so .bubble's `pre-wrap` would turn
    every source newline into a visible break and double the spacing. Streamdown
@@ -113,8 +133,12 @@ body {
   white-space: normal;
 }
 
-.markdown > :first-child { margin-top: 0; }
-.markdown > :last-child { margin-bottom: 0; }
+.markdown > :first-child {
+  margin-top: 0;
+}
+.markdown > :last-child {
+  margin-bottom: 0;
+}
 
 /* A wide table or code fence scrolls itself rather than widening the column. */
 .markdown table,
@@ -142,7 +166,9 @@ body {
   font: inherit;
 }
 
-.composer textarea:focus { outline: 1px solid var(--accent); }
+.composer textarea:focus {
+  outline: 1px solid var(--accent);
+}
 
 .composer button {
   align-self: flex-end;
@@ -155,7 +181,10 @@ body {
   cursor: pointer;
 }
 
-.composer button:disabled { opacity: 0.5; cursor: default; }
+.composer button:disabled {
+  opacity: 0.5;
+  cursor: default;
+}
 
 .error {
   margin: 0 16px 12px;
diff --git a/apps/web/tests/browser-api.test.ts b/apps/web/tests/browser-api.test.ts
index 7f640c6..71f49ba 100644
--- a/apps/web/tests/browser-api.test.ts
+++ b/apps/web/tests/browser-api.test.ts
@@ -11,10 +11,20 @@ test("TanStack mount exposes the Hono router and preserves authentication", asyn
   const previous = process.env.MCP_AUTH_TOKEN;
   try {
     process.env.MCP_AUTH_TOKEN = "test-token";
-    assert.equal((await mountedBrowserApp(new Request("http://localhost/api/browse/health"))).status, 401);
-    assert.equal((await mountedBrowserApp(new Request("http://localhost/api/browse/health", {
-      headers: { authorization: "Bearer test-token" },
-    }))).status, 200);
+    assert.equal(
+      (await mountedBrowserApp(new Request("http://localhost/api/browse/health"))).status,
+      401,
+    );
+    assert.equal(
+      (
+        await mountedBrowserApp(
+          new Request("http://localhost/api/browse/health", {
+            headers: { authorization: "Bearer test-token" },
+          }),
+        )
+      ).status,
+      200,
+    );
   } finally {
     if (previous === undefined) delete process.env.MCP_AUTH_TOKEN;
     else process.env.MCP_AUTH_TOKEN = previous;
@@ -25,7 +35,9 @@ test("chat discovers tools through in-process MCP without an HTTP server", async
   const session = await openMcpSession();
   try {
     assert.deepEqual(Object.keys(session.tools).sort(), ["browser_api", "browser_run"]);
-  } finally { await session.close(); }
+  } finally {
+    await session.close();
+  }
 });
 
 test("cancelled preview body reads return 499 instead of an unhandled 500", async (t) => {
@@ -39,15 +51,27 @@ test("cancelled preview body reads return 499 instead of an unhandled 500", asyn
     });
     return new Response(stream);
   });
-  const response = await proxyBrowserRequest(new Request("http://localhost/api/screen", {
-    method: "POST", body: '{"cdpUrl":"9222"}', signal: controller.signal,
-  }), "/screen", dispatch);
+  const response = await proxyBrowserRequest(
+    new Request("http://localhost/api/screen", {
+      method: "POST",
+      body: '{"cdpUrl":"9222"}',
+      signal: controller.signal,
+    }),
+    "/screen",
+    dispatch,
+  );
   assert.equal(response.status, 499);
 });
 
 test("an unreachable backend returns a useful start error", async (t) => {
-  const dispatch = t.mock.fn(async () => { throw new TypeError("fetch failed"); });
-  const response = await proxyBrowserRequest(new Request("http://localhost/api/browser", { method: "POST" }), "/browser", dispatch);
+  const dispatch = t.mock.fn(async () => {
+    throw new TypeError("fetch failed");
+  });
+  const response = await proxyBrowserRequest(
+    new Request("http://localhost/api/browser", { method: "POST" }),
+    "/browser",
+    dispatch,
+  );
   assert.equal(response.status, 502);
   assert.match((await response.json()).error, /pnpm dev/);
 });
@@ -55,11 +79,22 @@ test("an unreachable backend returns a useful start error", async (t) => {
 test("successful create and preview responses preserve their bodies", async (t) => {
   const handle = { provider: "cdp", cdpUrl: "9222" };
   const fetch = t.mock.fn(async () => Response.json(handle, { status: 201 }));
-  const response = await proxyBrowserRequest(new Request("http://localhost/api/browser", { method: "POST" }), "/browser", fetch);
+  const response = await proxyBrowserRequest(
+    new Request("http://localhost/api/browser", { method: "POST" }),
+    "/browser",
+    fetch,
+  );
   assert.equal(response.status, 201);
   assert.deepEqual(await response.json(), handle);
-  fetch.mock.mockImplementation(async () => new Response(new Uint8Array([255, 216, 255]), { headers: { "content-type": "image/jpeg" } }));
-  const preview = await proxyBrowserRequest(new Request("http://localhost/api/screen", { method: "POST", body: JSON.stringify(handle) }), "/screen", fetch);
+  fetch.mock.mockImplementation(
+    async () =>
+      new Response(new Uint8Array([255, 216, 255]), { headers: { "content-type": "image/jpeg" } }),
+  );
+  const preview = await proxyBrowserRequest(
+    new Request("http://localhost/api/screen", { method: "POST", body: JSON.stringify(handle) }),
+    "/screen",
+    fetch,
+  );
   assert.equal(preview.headers.get("content-type"), "image/jpeg");
   assert.deepEqual(new Uint8Array(await preview.arrayBuffer()), new Uint8Array([255, 216, 255]));
 });
diff --git a/apps/web/vite.config.ts b/apps/web/vite.config.ts
index 8979a54..a78f369 100644
--- a/apps/web/vite.config.ts
+++ b/apps/web/vite.config.ts
@@ -1,12 +1,11 @@
-import { fileURLToPath } from "node:url";
 import { readFileSync } from "node:fs";
-
-import { defineConfig, loadEnv } from "vite";
-import react from "@vitejs/plugin-react";
+import { fileURLToPath } from "node:url";
+import { cloudflare } from "@cloudflare/vite-plugin";
 import tailwindcss from "@tailwindcss/vite";
 import { tanstackStart } from "@tanstack/react-start/plugin/vite";
-import { cloudflare } from "@cloudflare/vite-plugin";
+import react from "@vitejs/plugin-react";
 import { nitro } from "nitro/vite";
+import { defineConfig, loadEnv } from "vite";
 
 const workspaceRoot = fileURLToPath(new URL("../..", import.meta.url));
 
@@ -21,28 +20,36 @@ export default defineConfig(({ mode, command }) => {
 
   return {
     resolve: {
-      alias: [{
-        find: "@browse-code-mode/mcp-server/runtime",
-        replacement: mode === "cloudflare"
-          ? "@browse-code-mode/mcp-server/worker-runtime"
-          : "@browse-code-mode/mcp-server/bundled-runtime",
-      }],
+      alias: [
+        {
+          find: "@browse-code-mode/mcp-server/runtime",
+          replacement:
+            mode === "cloudflare"
+              ? "@browse-code-mode/mcp-server/worker-runtime"
+              : "@browse-code-mode/mcp-server/bundled-runtime",
+        },
+      ],
     },
     server: { port: 3000, strictPort: true },
     plugins: [
       {
         name: "browse-node-wasm",
-        resolveId(id) { if (id === "virtual:browse-wasm") return "\0browse-wasm"; },
+        resolveId(id) {
+          if (id === "virtual:browse-wasm") return "\0browse-wasm";
+        },
         load(id) {
           if (id !== "\0browse-wasm") return;
-          const binary = readFileSync(new URL("../../packages/mcp-server/node_modules/@jitl/quickjs-wasmfile-release-sync/dist/emscripten-module.wasm", import.meta.url));
+          const binary = readFileSync(
+            new URL(
+              "../../packages/mcp-server/node_modules/@jitl/quickjs-wasmfile-release-sync/dist/emscripten-module.wasm",
+              import.meta.url,
+            ),
+          );
           return `export default Uint8Array.from(atob(${JSON.stringify(binary.toString("base64"))}), c => c.charCodeAt(0)).buffer;`;
         },
       },
       tailwindcss(),
-      ...(mode === "cloudflare"
-        ? [cloudflare({ viteEnvironment: { name: "ssr" } })]
-        : []),
+      ...(mode === "cloudflare" ? [cloudflare({ viteEnvironment: { name: "ssr" } })] : []),
       tanstackStart(),
       ...(mode === "cloudflare" || command !== "build"
         ? []
diff --git a/examples/01-hello-world/index.ts b/examples/01-hello-world/index.ts
index f369836..816a7b8 100644
--- a/examples/01-hello-world/index.ts
+++ b/examples/01-hello-world/index.ts
@@ -6,10 +6,10 @@
  */
 
 import { anthropic } from "@ai-sdk/anthropic";
-import { generateText, stepCountIs } from "ai";
+import { localProvider } from "@browse-code-mode/mcp-server/local-browser";
 import { browserTools, instructions } from "@browse-code-mode/tools/ai-sdk";
 import { providerBrowser } from "@browse-code-mode/tools/browser";
-import { localProvider } from "@browse-code-mode/mcp-server/local-browser";
+import { generateText, stepCountIs } from "ai";
 
 const prompt = process.argv[2] ?? "What's the weather in San Francisco right now?";
 
diff --git a/examples/02-mcp-server/index.ts b/examples/02-mcp-server/index.ts
index ae5b477..3a0541c 100644
--- a/examples/02-mcp-server/index.ts
+++ b/examples/02-mcp-server/index.ts
@@ -10,11 +10,10 @@
  */
 
 import { createServer } from "node:http";
-
+import { localProvider } from "@browse-code-mode/mcp-server/local-browser";
+import { createBrowserToolkit, providerBrowser } from "@browse-code-mode/tools";
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
-import { createBrowserToolkit, providerBrowser } from "@browse-code-mode/tools";
-import { localProvider } from "@browse-code-mode/mcp-server/local-browser";
 
 const port = Number(process.env.PORT ?? 3000);
 const host = "127.0.0.1";
@@ -56,7 +55,10 @@ function createMcpServer(): McpServer {
 
   server.registerTool(
     sessions.start.name,
-    { description: sessions.start.description, annotations: { readOnlyHint: false, openWorldHint: true } },
+    {
+      description: sessions.start.description,
+      annotations: { readOnlyHint: false, openWorldHint: true },
+    },
     async ({ signal }) => json(await sessions.start.execute(signal)),
   );
 
diff --git a/packages/mcp-server/api/index.ts b/packages/mcp-server/api/index.ts
index 23b9dfe..b5ab561 100644
--- a/packages/mcp-server/api/index.ts
+++ b/packages/mcp-server/api/index.ts
@@ -1,8 +1,8 @@
-import { handle } from "hono/vercel";
 import { Hono } from "hono";
+import { handle } from "hono/vercel";
 import { createApp } from "../src/app.ts";
-import { loadConfig } from "../src/config.ts";
 import { providerFromEnv } from "../src/browse/providers.ts";
+import { loadConfig } from "../src/config.ts";
 
 const app = createApp({ config: loadConfig(process.env), provider: providerFromEnv(process.env) });
 const router = new Hono();
diff --git a/packages/mcp-server/src/app.ts b/packages/mcp-server/src/app.ts
index b481d53..c694211 100644
--- a/packages/mcp-server/src/app.ts
+++ b/packages/mcp-server/src/app.ts
@@ -10,17 +10,16 @@
 import { WebStandardStreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/webStandardStreamableHttp.js";
 import { Hono } from "hono";
 import { z } from "zod";
-import { staticProvider } from "./browse/provider.ts";
 import { BrowserSession } from "./browse/driver.ts";
-import { captureScreenshot } from "./core.ts";
-
-import { renderApiDts, renderCheatsheet, PROGRAM_GUIDE } from "./browse/dts.ts";
+import { PROGRAM_GUIDE, renderApiDts, renderCheatsheet } from "./browse/dts.ts";
+import { staticProvider } from "./browse/provider.ts";
 import type { ServerConfig } from "./config.ts";
+import { captureScreenshot } from "./core.ts";
 import {
+  type CreateServerOptions,
   createMcpServer,
   SERVER_NAME,
   SERVER_VERSION,
-  type CreateServerOptions,
 } from "./mcp/server.ts";
 
 export interface AppDeps {
@@ -48,9 +47,21 @@ export function createApp({
   app.onError((error, c) => {
     if (c.req.raw.signal.aborted) return new Response(null, { status: 499 });
     if (error.name === "NoBrowserError")
-      return c.json({ error: "No browser configured. Run pnpm dev locally, or configure BROWSE_PROVIDER and its credentials." }, 503);
+      return c.json(
+        {
+          error:
+            "No browser configured. Run pnpm dev locally, or configure BROWSE_PROVIDER and its credentials.",
+        },
+        503,
+      );
     log(`Browser operation failed: ${error.message}`);
-    return c.json({ error: "Browser operation failed. Check the server logs and browser provider configuration." }, 500);
+    return c.json(
+      {
+        error:
+          "Browser operation failed. Check the server logs and browser provider configuration.",
+      },
+      500,
+    );
   });
 
   // ---------------------------------------------------------------- middleware
@@ -84,11 +95,8 @@ export function createApp({
   });
 
   app.delete("/browser", async (c) => {
-    const parsed = browserHandleSchema.safeParse(
-      await c.req.json().catch(() => null),
-    );
-    if (!parsed.success)
-      return c.json({ error: "A browser handle is required." }, 400);
+    const parsed = browserHandleSchema.safeParse(await c.req.json().catch(() => null));
+    if (!parsed.success) return c.json({ error: "A browser handle is required." }, 400);
     if (parsed.data.provider !== provider.name)
       return c.json({ error: "Wrong browser provider." }, 400);
     await provider.shutdown(parsed.data);
@@ -127,11 +135,7 @@ export function createApp({
   /** Inspect any local or hosted CDP browser without HTTP discovery endpoints. */
   app.get("/browser", async (c) => {
     const endpoint = c.req.query("cdpUrl") ?? config.defaultCdpUrl;
-    if (!endpoint)
-      return c.json(
-        { error: "No cdpUrl given and no default configured." },
-        400,
-      );
+    if (!endpoint) return c.json({ error: "No cdpUrl given and no default configured." }, 400);
 
     try {
       const session = await (connect ?? BrowserSession.connect)({
@@ -146,10 +150,7 @@ export function createApp({
         await session.close();
       }
     } catch (error) {
-      return c.json(
-        { error: error instanceof Error ? error.message : String(error) },
-        502,
-      );
+      return c.json({ error: error instanceof Error ? error.message : String(error) }, 502);
     }
   });
 
@@ -178,8 +179,7 @@ export function createApp({
           jsonrpc: "2.0",
           error: {
             code: -32000,
-            message:
-              "This server is stateless. Send requests as POSTs; no session is kept.",
+            message: "This server is stateless. Send requests as POSTs; no session is kept.",
           },
           id: null,
         },
@@ -265,9 +265,7 @@ async function closeQuietly(
 }
 
 function exposedOption(config: ServerConfig): { exposed?: readonly string[] } {
-  return config.allowCommands.length > 0
-    ? { exposed: config.allowCommands }
-    : {};
+  return config.allowCommands.length > 0 ? { exposed: config.allowCommands } : {};
 }
 
 /** Constant-time-ish comparison, to keep token checks from leaking length. */
diff --git a/packages/mcp-server/src/browse/cdp.ts b/packages/mcp-server/src/browse/cdp.ts
index d310624..3e9c75e 100644
--- a/packages/mcp-server/src/browse/cdp.ts
+++ b/packages/mcp-server/src/browse/cdp.ts
@@ -45,8 +45,7 @@ export async function resolveCdpUrl(
   }
 
   const payload = await fetchJson(new URL("/json/version", origin), timeoutMs, signal);
-  const webSocketDebuggerUrl = (payload as { webSocketDebuggerUrl?: unknown })
-    .webSocketDebuggerUrl;
+  const webSocketDebuggerUrl = (payload as { webSocketDebuggerUrl?: unknown }).webSocketDebuggerUrl;
   if (typeof webSocketDebuggerUrl !== "string") {
     throw new CdpEndpointError(
       `${origin} answered /json/version without a webSocketDebuggerUrl. Is it a Chrome DevTools endpoint?`,
diff --git a/packages/mcp-server/src/browse/commands.ts b/packages/mcp-server/src/browse/commands.ts
index e609564..bbb8358 100644
--- a/packages/mcp-server/src/browse/commands.ts
+++ b/packages/mcp-server/src/browse/commands.ts
@@ -149,8 +149,7 @@ export const COMMANDS: CommandSpec[] = [
     fn: "snapshot",
     wire: "snapshot",
     cli: "browse snapshot",
-    summary:
-      "Capture the accessibility tree and refresh the `@ref` map used by element commands.",
+    summary: "Capture the accessibility tree and refresh the `@ref` map used by element commands.",
     options: [
       {
         name: "full",
@@ -244,9 +243,7 @@ export const COMMANDS: CommandSpec[] = [
     cli: "browse highlight <target>",
     summary: "Flash a visual highlight around an element.",
     args: [{ name: "target", param: "selector", type: "string", doc: SELECTOR_DOC }],
-    options: [
-      { name: "durationMs", type: "number", doc: "Defaults to 2000." },
-    ],
+    options: [{ name: "durationMs", type: "number", doc: "Defaults to 2000." }],
     returns: "{ highlighted: true }",
   },
 
@@ -324,8 +321,8 @@ export const COMMANDS: CommandSpec[] = [
         name: "frame",
         type: "string",
         doc:
-          "Run inside an iframe instead of the top page: a snapshot frame index (`\"2\"` for refs `[2-…]`), " +
-          "the iframe's ref (`\"@0-10\"`), or an iframe selector (`\"#checkout\"`, `\"#outer >> iframe\"`). " +
+          'Run inside an iframe instead of the top page: a snapshot frame index (`"2"` for refs `[2-…]`), ' +
+          'the iframe\'s ref (`"@0-10"`), or an iframe selector (`"#checkout"`, `"#outer >> iframe"`). ' +
           "Cross-site frames work too.",
       },
     ],
@@ -364,9 +361,7 @@ export const COMMANDS: CommandSpec[] = [
       { name: "width", type: "number" },
       { name: "height", type: "number" },
     ],
-    options: [
-      { name: "scale", type: "number", doc: "Device pixel ratio. Defaults to 1." },
-    ],
+    options: [{ name: "scale", type: "number", doc: "Device pixel ratio. Defaults to 1." }],
     returns: "{ viewport: { height: number; width: number } }",
   },
   {
@@ -483,8 +478,7 @@ export const COMMANDS: CommandSpec[] = [
     cli: "browse tab new [url]",
     summary: "Open a new tab and make it active.",
     args: [{ name: "url", type: "string", optional: true }],
-    returns:
-      "{ active: true; index: number; targetId?: string; title?: string; url: string }",
+    returns: "{ active: true; index: number; targetId?: string; title?: string; url: string }",
   },
   {
     group: "tab",
@@ -500,8 +494,7 @@ export const COMMANDS: CommandSpec[] = [
         doc: "Prefer the `targetId` from `tab.list()`; indexes shift as tabs open and close.",
       },
     ],
-    returns:
-      "{ index: number; switched: true; targetId?: string; title?: string; url: string }",
+    returns: "{ index: number; switched: true; targetId?: string; title?: string; url: string }",
   },
   {
     group: "tab",
@@ -509,11 +502,8 @@ export const COMMANDS: CommandSpec[] = [
     wire: "tab.close",
     cli: "browse tab close [tab]",
     summary: "Close a tab. Defaults to the active tab; refuses to close the last one.",
-    args: [
-      { name: "tab", type: "string | number", optional: true, coerce: "string" },
-    ],
-    returns:
-      "{ closed: true; index: number; selectedTargetId?: string; targetId?: string }",
+    args: [{ name: "tab", type: "string | number", optional: true, coerce: "string" }],
+    returns: "{ closed: true; index: number; selectedTargetId?: string; targetId?: string }",
   },
 
   // ------------------------------------------------------------------- session
@@ -608,10 +598,7 @@ export function commandGroups(): GroupName[] {
  * Build driver params from the positional arguments and trailing options object
  * a sandbox program passed, following the spec's arg/option declarations.
  */
-export function buildParams(
-  spec: CommandSpec,
-  args: readonly unknown[],
-): Record<string, unknown> {
+export function buildParams(spec: CommandSpec, args: readonly unknown[]): Record<string, unknown> {
   const params: Record<string, unknown> = {};
   const argSpecs = spec.args ?? [];
 
diff --git a/packages/mcp-server/src/browse/driver.ts b/packages/mcp-server/src/browse/driver.ts
index 99894d7..17ca2c7 100644
--- a/packages/mcp-server/src/browse/driver.ts
+++ b/packages/mcp-server/src/browse/driver.ts
@@ -13,17 +13,21 @@
 
 import { NodeHtmlMarkdown } from "node-html-markdown";
 import {
-  connectBrowser,
   type BrowserContext,
+  connectBrowser,
   type LoadState,
   type MouseButton,
   type Page,
 } from "./page.ts";
+import {
+  emptyRefMaps,
+  type FrameTarget,
+  type RefMaps,
+  type ResolvedSelector,
+  resolveSelector,
+} from "./selectors.ts";
 import type { OpenSocket } from "./transport.ts";
 
-
-import { emptyRefMaps, resolveSelector, type FrameTarget, type RefMaps, type ResolvedSelector } from "./selectors.ts";
-
 /** Raised for command-level failures, mirroring the CLI's error surface. */
 export class BrowseCommandError extends Error {
   readonly code: string | undefined;
@@ -76,7 +80,12 @@ export class BrowserSession implements CommandRunner {
   }
 
   /** Attach to a browser that already exists. */
-  static async connect({ cdpUrl, signal, onEvent, openSocket }: ConnectOptions): Promise<BrowserSession> {
+  static async connect({
+    cdpUrl,
+    signal,
+    onEvent,
+    openSocket,
+  }: ConnectOptions): Promise<BrowserSession> {
     const context = await connectBrowser(cdpUrl, signal, openSocket);
     onEvent?.("attached over CDP");
     return new BrowserSession(context, cdpUrl);
@@ -89,7 +98,10 @@ export class BrowserSession implements CommandRunner {
   async run(command: string, params: Params): Promise<unknown> {
     const handler = HANDLERS[command];
     if (!handler) throw new BrowseCommandError(`Unknown command "${command}".`);
-    if (["open", "reload", "back", "forward", "tab.new", "tab.switch", "tab.close"].includes(command)) this.setRefMaps({});
+    if (
+      ["open", "reload", "back", "forward", "tab.new", "tab.switch", "tab.close"].includes(command)
+    )
+      this.setRefMaps({});
     return handler(this, params);
   }
 
@@ -340,13 +352,18 @@ const HANDLERS: Record<string, Handler> = {
     const quality = optNum(params, "quality");
     const clip = params.clip;
     const buffer = await page.screenshot({
-      ...(optBool(params, "fullPage") === undefined ? {} : { fullPage: optBool(params, "fullPage") }),
+      ...(optBool(params, "fullPage") === undefined
+        ? {}
+        : { fullPage: optBool(params, "fullPage") }),
       ...(type === undefined ? {} : { type: type as "png" | "jpeg" }),
       ...(quality === undefined ? {} : { quality }),
       ...(clip === undefined ? {} : { clip: clip as never }),
     });
 
-    if (optStr(params, "path")) throw new BrowseCommandError("Screenshot paths are unavailable; use the returned base64 data.");
+    if (optStr(params, "path"))
+      throw new BrowseCommandError(
+        "Screenshot paths are unavailable; use the returned base64 data.",
+      );
     return { base64: buffer };
   },
 
@@ -377,7 +394,9 @@ const HANDLERS: Record<string, Handler> = {
     } else if (type === "timeout") {
       const ms = Number(arg ?? 0);
       if (!Number.isInteger(ms) || ms < 0) {
-        throw new BrowseCommandError("wait timeout requires a non-negative integer of milliseconds.");
+        throw new BrowseCommandError(
+          "wait timeout requires a non-negative integer of milliseconds.",
+        );
       }
       await page.waitForTimeout(ms);
     } else {
@@ -487,7 +506,13 @@ const HANDLERS: Record<string, Handler> = {
     const active = await context.activePage();
     const resolved = tab
       ? await resolveTab(session, tab)
-      : { index: Math.max(0, pages.findIndex((p) => p.pageId === active?.pageId)), page: active ?? pages[0]! };
+      : {
+          index: Math.max(
+            0,
+            pages.findIndex((p) => p.pageId === active?.pageId),
+          ),
+          page: active ?? pages[0]!,
+        };
 
     const closedTargetId = resolved.page.pageId;
     await resolved.page.close();
diff --git a/packages/mcp-server/src/browse/dts.ts b/packages/mcp-server/src/browse/dts.ts
index aecb1b9..2db011c 100644
--- a/packages/mcp-server/src/browse/dts.ts
+++ b/packages/mcp-server/src/browse/dts.ts
@@ -6,7 +6,7 @@
  * types, and the sandbox globals at the same time.
  */
 
-import { COMMANDS, commandGroups, SHARED_TYPES, type CommandSpec } from "./commands.ts";
+import { COMMANDS, type CommandSpec, commandGroups, SHARED_TYPES } from "./commands.ts";
 
 export interface RenderOptions {
   /** Restrict output to these `group.fn` keys. Defaults to all. */
@@ -15,7 +15,8 @@ export interface RenderOptions {
 
 const GROUP_DOCS: Record<string, string> = {
   browse: "Top-level `browse` commands: navigation, snapshots, elements, and page state.",
-  mouse: "Raw coordinate input (`browse mouse ...`). Prefer refs when the element is in a snapshot.",
+  mouse:
+    "Raw coordinate input (`browse mouse ...`). Prefer refs when the element is in a snapshot.",
   tab: "Tab management (`browse tab ...`).",
   network: "Network capture (`browse network ...`).",
 };
@@ -89,7 +90,9 @@ export function renderCheatsheet(options: RenderOptions = {}): string {
     if (specs.length === 0) continue;
     lines.push(`## ${group}`);
     for (const spec of specs) {
-      lines.push(`- \`${spec.group}.${spec.fn}${signature(spec)}\` — ${spec.summary} (\`${spec.cli}\`)`);
+      lines.push(
+        `- \`${spec.group}.${spec.fn}${signature(spec)}\` — ${spec.summary} (\`${spec.cli}\`)`,
+      );
     }
     lines.push("");
   }
@@ -115,9 +118,7 @@ function docComment(spec: CommandSpec): string {
   const lines: string[] = [spec.summary, "", `CLI: \`${spec.cli}\``];
 
   const documented = [
-    ...(spec.args ?? [])
-      .filter((arg) => arg.doc)
-      .map((arg) => `@param ${arg.name} ${arg.doc}`),
+    ...(spec.args ?? []).filter((arg) => arg.doc).map((arg) => `@param ${arg.name} ${arg.doc}`),
     ...(spec.options ?? [])
       .filter((option) => option.doc)
       .map((option) => `@param options.${option.name} ${option.doc}`),
@@ -134,9 +135,7 @@ function signature(spec: CommandSpec): string {
   );
 
   if (spec.options?.length) {
-    const fields = spec.options
-      .map((option) => `${option.name}?: ${option.type}`)
-      .join("; ");
+    const fields = spec.options.map((option) => `${option.name}?: ${option.type}`).join("; ");
     params.push(`options?: { ${fields} }`);
   }
 
diff --git a/packages/mcp-server/src/browse/host-functions.ts b/packages/mcp-server/src/browse/host-functions.ts
index 56b11f2..54f2faf 100644
--- a/packages/mcp-server/src/browse/host-functions.ts
+++ b/packages/mcp-server/src/browse/host-functions.ts
@@ -12,8 +12,8 @@ type HostFunctions = Record<string, Record<string, (...args: unknown[]) => Promi
 import {
   buildParams,
   COMMANDS,
-  commandGroups,
   type CommandSpec,
+  commandGroups,
   type GroupName,
 } from "./commands.ts";
 import type { CommandRunner } from "./driver.ts";
@@ -71,7 +71,8 @@ export function createHostFunctions(options: HostFunctionOptions): HostFunctionB
     const key = `${spec.group}.${spec.fn}`;
     if (!isPermitted(key, options)) continue;
     exposed.push(key);
-    hostFunctions[spec.group]![spec.fn] = (...args: unknown[]) => invoke(spec, args, calls, counter, options);
+    hostFunctions[spec.group]![spec.fn] = (...args: unknown[]) =>
+      invoke(spec, args, calls, counter, options);
   }
 
   return { hostFunctions, calls, exposed };
@@ -146,10 +147,7 @@ function isPermitted(key: string, options: HostFunctionOptions): boolean {
  * Render a call as the shell command it stands for, so a program's trace reads
  * like the `browse` invocations an agent would otherwise have typed.
  */
-export function formatCall(
-  spec: CommandSpec,
-  params: Record<string, unknown>,
-): string {
+export function formatCall(spec: CommandSpec, params: Record<string, unknown>): string {
   const words = cliWords(spec.cli);
   const positional = (spec.args ?? [])
     .map((arg) => params[arg.param ?? arg.name])
diff --git a/packages/mcp-server/src/browse/page.ts b/packages/mcp-server/src/browse/page.ts
index 89545a5..9aa601b 100644
--- a/packages/mcp-server/src/browse/page.ts
+++ b/packages/mcp-server/src/browse/page.ts
@@ -1,13 +1,13 @@
 /** Direct CDP implementation: no browser extension, filesystem, or Node APIs. */
-import { CdpConnection, openWebSocket, type OpenSocket } from "./transport.ts";
+
 import { resolveCdpUrl } from "./cdp.ts";
 import type { FrameTarget, ResolvedSelector } from "./selectors.ts";
+import { CdpConnection, type OpenSocket, openWebSocket } from "./transport.ts";
 
 export type LoadState = "load" | "domcontentloaded" | "networkidle";
 export type MouseButton = "left" | "middle" | "right";
 type NavigationOptions = { timeout?: number; waitUntil?: LoadState };
-const pause = (ms: number) =>
-  new Promise<void>((resolve) => setTimeout(resolve, ms));
+const pause = (ms: number) => new Promise<void>((resolve) => setTimeout(resolve, ms));
 
 export async function connectBrowser(
   cdpUrl: string,
@@ -57,8 +57,7 @@ export class BrowserContext {
     const selected = pages.find((p) => p.pageId === this.selected);
     if (selected) return selected;
     for (const page of pages) {
-      if (await page.evaluate("document.hasFocus()").catch(() => false))
-        return page;
+      if (await page.evaluate("document.hasFocus()").catch(() => false)) return page;
     }
     return pages[0];
   }
@@ -93,12 +92,7 @@ export class Page {
   /** Each session's frames → the id of their main-world execution context. */
   private worlds = new Map<string, Map<string, number>>();
   private runtimeEnabled = new Map<string, Promise<unknown>>();
-  constructor(
-    cdp: CdpConnection,
-    id: string,
-    sessionId: string,
-    signal?: AbortSignal,
-  ) {
+  constructor(cdp: CdpConnection, id: string, sessionId: string, signal?: AbortSignal) {
     this.cdp = cdp;
     this.pageId = id;
     this.sessionId = sessionId;
@@ -127,10 +121,7 @@ export class Page {
       if (method === "Network.requestWillBeSent") {
         this.requests.add(params.requestId);
         this.networkChangedAt = Date.now();
-      } else if (
-        method === "Network.loadingFinished" ||
-        method === "Network.loadingFailed"
-      ) {
+      } else if (method === "Network.loadingFinished" || method === "Network.loadingFailed") {
         this.requests.delete(params.requestId);
         this.networkChangedAt = Date.now();
       }
@@ -168,8 +159,7 @@ export class Page {
   }
   private ownsSession(session: string | undefined): boolean {
     if (session === this.sessionId) return true;
-    for (const frame of this.oopifs.values())
-      if (frame.sessionId === session) return true;
+    for (const frame of this.oopifs.values()) if (frame.sessionId === session) return true;
     return false;
   }
   private trackWorld(session: string, method: string, params: any) {
@@ -207,7 +197,9 @@ export class Page {
       awaitPromise: true,
     });
     if (response.exceptionDetails)
-      throw new Error(response.exceptionDetails.exception?.description ?? response.exceptionDetails.text);
+      throw new Error(
+        response.exceptionDetails.exception?.description ?? response.exceptionDetails.text,
+      );
     return response.result.value;
   }
   /** Wait until every nested iframe target has been attached. */
@@ -230,7 +222,9 @@ export class Page {
       const entry = [...this.oopifs].find(([, frame]) => frame.sessionId === sessionId);
       if (!entry) throw new Error("The element's frame is no longer attached.");
       const [frameId, { parentSessionId }] = entry;
-      const { backendNodeId } = await this.sendTo(parentSessionId, "DOM.getFrameOwner", { frameId });
+      const { backendNodeId } = await this.sendTo(parentSessionId, "DOM.getFrameOwner", {
+        frameId,
+      });
       const { model } = await this.sendTo(parentSessionId, "DOM.getBoxModel", { backendNodeId });
       x += model.content[0];
       y += model.content[1];
@@ -247,11 +241,18 @@ export class Page {
     ];
     const perSession = await Promise.all(
       sessions.map(async ({ sessionId, parentSessionId }) => {
-        const { frameTree } = await this.sendTo(sessionId, "Page.getFrameTree").catch(() => ({ frameTree: undefined }));
+        const { frameTree } = await this.sendTo(sessionId, "Page.getFrameTree").catch(() => ({
+          frameTree: undefined,
+        }));
         if (!frameTree) return [];
         const found: SnapshotFrame[] = [];
         const walk = (node: any, root: boolean) => {
-          found.push({ frameId: node.frame.id, sessionId, ownerSession: root ? parentSessionId : sessionId, nodes: [] });
+          found.push({
+            frameId: node.frame.id,
+            sessionId,
+            ownerSession: root ? parentSessionId : sessionId,
+            nodes: [],
+          });
           for (const child of node.childFrames ?? []) walk(child, false);
         };
         walk(frameTree, true);
@@ -263,9 +264,13 @@ export class Page {
       frames.map(async (frame) => {
         // A frame can navigate or detach mid-snapshot; leave it out rather than fail.
         const [tree, owner] = await Promise.all([
-          this.sendTo(frame.sessionId, "Accessibility.getFullAXTree", { frameId: frame.frameId }).catch(() => undefined),
+          this.sendTo(frame.sessionId, "Accessibility.getFullAXTree", {
+            frameId: frame.frameId,
+          }).catch(() => undefined),
           frame.ownerSession
-            ? this.sendTo(frame.ownerSession, "DOM.getFrameOwner", { frameId: frame.frameId }).catch(() => undefined)
+            ? this.sendTo(frame.ownerSession, "DOM.getFrameOwner", {
+                frameId: frame.frameId,
+              }).catch(() => undefined)
             : undefined,
         ]);
         frame.nodes = tree?.nodes ?? [];
@@ -282,8 +287,7 @@ export class Page {
     });
     if (response.exceptionDetails)
       throw new Error(
-        response.exceptionDetails.exception?.description ??
-          response.exceptionDetails.text,
+        response.exceptionDetails.exception?.description ?? response.exceptionDetails.text,
       );
     return response.result.value;
   }
@@ -305,8 +309,7 @@ export class Page {
   private async history(delta: number, options: NavigationOptions) {
     const history = await this.send("Page.getNavigationHistory");
     const entry = history.entries[history.currentIndex + delta];
-    if (entry)
-      await this.send("Page.navigateToHistoryEntry", { entryId: entry.id });
+    if (entry) await this.send("Page.navigateToHistoryEntry", { entryId: entry.id });
     await this.waitForLoadState(options.waitUntil ?? "load", options.timeout);
   }
   goBack(options: NavigationOptions = {}) {
@@ -326,18 +329,13 @@ export class Page {
       const started = Date.now();
       return this.poll(
         async () =>
-          this.requests.size === 0 &&
-          Date.now() - Math.max(started, this.networkChangedAt) >= 500,
+          this.requests.size === 0 && Date.now() - Math.max(started, this.networkChangedAt) >= 500,
         timeout,
       );
     }
     await this.poll(async () => {
-      const ready = await this.evaluate("document.readyState").catch(
-        () => "loading",
-      );
-      return state === "domcontentloaded"
-        ? ready !== "loading"
-        : ready === "complete";
+      const ready = await this.evaluate("document.readyState").catch(() => "loading");
+      return state === "domcontentloaded" ? ready !== "loading" : ready === "complete";
     }, timeout);
   }
   async poll(check: () => Promise<boolean>, timeout: number) {
@@ -379,8 +377,7 @@ export class Page {
     const parts = combo.split("+");
     const key = parts.pop()!;
     const modifiers = parts.reduce(
-      (n, p) =>
-        n | ({ Alt: 1, Control: 2, Ctrl: 2, Meta: 4, Shift: 8 }[p] ?? 0),
+      (n, p) => n | ({ Alt: 1, Control: 2, Ctrl: 2, Meta: 4, Shift: 8 }[p] ?? 0),
       0,
     );
     const codes: Record<string, number> = {
@@ -399,12 +396,7 @@ export class Page {
       PageDown: 34,
     };
     const code = codes[key] ?? key.toUpperCase().charCodeAt(0);
-    const text =
-      key === "Enter"
-        ? "\r"
-        : key.length === 1 && !(modifiers & 7)
-          ? key
-          : undefined;
+    const text = key === "Enter" ? "\r" : key.length === 1 && !(modifiers & 7) ? key : undefined;
     await this.send("Input.dispatchKeyEvent", {
       type: "keyDown",
       key,
@@ -419,10 +411,7 @@ export class Page {
       windowsVirtualKeyCode: code,
     });
   }
-  async type(
-    text: string,
-    options?: { delay?: number; withMistakes?: boolean },
-  ) {
+  async type(text: string, options?: { delay?: number; withMistakes?: boolean }) {
     if (options?.delay || options?.withMistakes)
       for (const char of text) {
         if (options.withMistakes && Math.random() < 0.08) {
@@ -438,10 +427,7 @@ export class Page {
   async click(
     x: number,
     y: number,
-    {
-      button = "left",
-      clickCount = 1,
-    }: { button?: MouseButton; clickCount?: number } = {},
+    { button = "left", clickCount = 1 }: { button?: MouseButton; clickCount?: number } = {},
   ) {
     await this.hover(x, y);
     await this.send("Input.dispatchMouseEvent", {
@@ -524,9 +510,7 @@ export class Page {
     const { data } = await this.send("Page.captureScreenshot", {
       format: options.type ?? "png",
       ...(options.quality === undefined ? {} : { quality: options.quality }),
-      ...(clip
-        ? { clip: { ...clip, scale: 1 }, captureBeyondViewport: true }
-        : {}),
+      ...(clip ? { clip: { ...clip, scale: 1 }, captureBeyondViewport: true } : {}),
     });
     return data as string;
   }
@@ -578,7 +562,8 @@ export class Page {
         if (shown && ref) {
           // Resolve refs using backend node IDs, never a server-side page registry.
           xpathMap[ref] = `backend=${node.backendDOMNodeId}`;
-          const url = node.properties?.find((p: { name: string }) => p.name === "url")?.value?.value;
+          const url = node.properties?.find((p: { name: string }) => p.name === "url")?.value
+            ?.value;
           if (url) urlMap[ref] = url;
         }
         if (shown)
@@ -588,7 +573,8 @@ export class Page {
         const childDepth = depth + (shown ? 1 : 0);
         for (const child of node.childIds ?? [])
           visit(byId.get(child), childDepth, node.ignored ? parentName : name);
-        const inner = node.backendDOMNodeId && hosted.get(`${frame.sessionId}:${node.backendDOMNodeId}`);
+        const inner =
+          node.backendDOMNodeId && hosted.get(`${frame.sessionId}:${node.backendDOMNodeId}`);
         if (inner) renderFrame(inner, childDepth);
       };
       for (const node of frame.nodes)
@@ -681,7 +667,9 @@ export class Locator {
       if (index === hops.length - 1) return { sessionId, objectId: result.objectId };
 
       // Step into the iframe this hop matched.
-      const { node } = await this.page.sendTo(sessionId, "DOM.describeNode", { objectId: result.objectId });
+      const { node } = await this.page.sendTo(sessionId, "DOM.describeNode", {
+        objectId: result.objectId,
+      });
       await this.page.sendTo(sessionId, "Runtime.releaseObject", { objectId: result.objectId });
       if (!node.frameId) throw new Error(`"${hop}" is not an iframe, so ">>" cannot enter it.`);
       await this.page.settleFrames();
@@ -692,10 +680,14 @@ export class Locator {
         contextId = undefined;
       } else {
         // Same process: an isolated world shares the frame's DOM.
-        ({ executionContextId: contextId } = await this.page.sendTo(sessionId, "Page.createIsolatedWorld", {
-          frameId: node.frameId,
-          worldName: "browse",
-        }));
+        ({ executionContextId: contextId } = await this.page.sendTo(
+          sessionId,
+          "Page.createIsolatedWorld",
+          {
+            frameId: node.frameId,
+            worldName: "browse",
+          },
+        ));
       }
     }
     return null;
@@ -732,7 +724,9 @@ export class Locator {
         awaitPromise: true,
       });
       if (result.exceptionDetails)
-        throw new Error(result.exceptionDetails.exception?.description ?? "Element operation failed.");
+        throw new Error(
+          result.exceptionDetails.exception?.description ?? "Element operation failed.",
+        );
       return result.result.value;
     } finally {
       await this.page
@@ -782,19 +776,13 @@ export class Locator {
     );
   }
   textContent(): Promise<string> {
-    return this.apply(
-      "if (!el) throw new Error('Element not found'); return el.textContent;",
-    );
+    return this.apply("if (!el) throw new Error('Element not found'); return el.textContent;");
   }
   innerHtml(): Promise<string> {
-    return this.apply(
-      "if (!el) throw new Error('Element not found'); return el.innerHTML;",
-    );
+    return this.apply("if (!el) throw new Error('Element not found'); return el.innerHTML;");
   }
   inputValue(): Promise<string> {
-    return this.apply(
-      "if (!el) throw new Error('Element not found'); return el.value;",
-    );
+    return this.apply("if (!el) throw new Error('Element not found'); return el.value;");
   }
   isVisible(): Promise<boolean> {
     return this.apply(
diff --git a/packages/mcp-server/src/browse/provider.ts b/packages/mcp-server/src/browse/provider.ts
index 8bea218..4ccb927 100644
--- a/packages/mcp-server/src/browse/provider.ts
+++ b/packages/mcp-server/src/browse/provider.ts
@@ -46,9 +46,7 @@ export function staticProvider(defaultCdpUrl?: string): BrowserProvider {
 /** Adapter for vendor SDKs or REST APIs; no SDK enters the core runtime. */
 export function browserProvider(options: {
   name: string;
-  create: (
-    options: CreateBrowserOptions,
-  ) => Promise<Omit<BrowserHandle, "provider">>;
+  create: (options: CreateBrowserOptions) => Promise<Omit<BrowserHandle, "provider">>;
   shutdown: (browser: BrowserHandle) => Promise<void>;
 }): BrowserProvider {
   return {
diff --git a/packages/mcp-server/src/browse/providers.ts b/packages/mcp-server/src/browse/providers.ts
index dce8bd2..03c1901 100644
--- a/packages/mcp-server/src/browse/providers.ts
+++ b/packages/mcp-server/src/browse/providers.ts
@@ -1,17 +1,10 @@
 /** Hosted lifecycles use fetch only and retain no process-local session state. */
-import {
-  browserProvider,
-  staticProvider,
-  type BrowserProvider,
-} from "./provider.ts";
+import { type BrowserProvider, browserProvider, staticProvider } from "./provider.ts";
 
 type Env = Record<string, string | undefined>;
 type Fetch = typeof fetch;
 
-export function providerFromEnv(
-  env: Env,
-  request: Fetch = fetch,
-): BrowserProvider {
+export function providerFromEnv(env: Env, request: Fetch = fetch): BrowserProvider {
   const name = env.BROWSE_PROVIDER ?? "cdp";
   if (name === "cdp") return staticProvider(env.BROWSE_CDP_URL);
   const timeout = Number(env.BROWSER_TIMEOUT_SECONDS ?? 600);
@@ -39,15 +32,13 @@ export function providerFromEnv(
         : AbortSignal.timeout(30_000),
     });
     if (deleting && [404, 410].includes(response.status)) return null;
-    if (!response.ok)
-      throw new Error(`${name} ${method} failed (HTTP ${response.status}).`);
+    if (!response.ok) throw new Error(`${name} ${method} failed (HTTP ${response.status}).`);
     if (response.status === 204) return null;
     return response.json() as Promise<Record<string, unknown>>;
   };
   const field = (data: Record<string, unknown> | null, key: string): string => {
     const value = data?.[key];
-    if (typeof value !== "string" || !value)
-      throw new Error(`${name} returned no ${key}.`);
+    if (typeof value !== "string" || !value) throw new Error(`${name} returned no ${key}.`);
     return value;
   };
   if (name === "browserbase") {
@@ -60,9 +51,7 @@ export function providerFromEnv(
           "POST",
           headers,
           {
-            ...(env.BROWSERBASE_PROJECT_ID
-              ? { projectId: env.BROWSERBASE_PROJECT_ID }
-              : {}),
+            ...(env.BROWSERBASE_PROJECT_ID ? { projectId: env.BROWSERBASE_PROJECT_ID } : {}),
             keepAlive: true,
             timeout,
           },
@@ -74,8 +63,7 @@ export function providerFromEnv(
         };
       },
       async shutdown(browser) {
-        if (!browser.sessionId)
-          throw new Error("Browserbase sessionId is required.");
+        if (!browser.sessionId) throw new Error("Browserbase sessionId is required.");
         await api(
           `https://api.browserbase.com/v1/sessions/${encodeURIComponent(browser.sessionId)}`,
           "POST",
@@ -108,8 +96,7 @@ export function providerFromEnv(
         };
       },
       async shutdown(browser) {
-        if (!browser.sessionId)
-          throw new Error("Kernel sessionId is required.");
+        if (!browser.sessionId) throw new Error("Kernel sessionId is required.");
         await api(
           `https://api.onkernel.com/browsers/${encodeURIComponent(browser.sessionId)}`,
           "DELETE",
diff --git a/packages/mcp-server/src/browse/transport.ts b/packages/mcp-server/src/browse/transport.ts
index 1a68728..d601717 100644
--- a/packages/mcp-server/src/browse/transport.ts
+++ b/packages/mcp-server/src/browse/transport.ts
@@ -1,17 +1,11 @@
 /** Web-standard CDP transport. Cloudflare supplies a fetch-upgrade socket factory. */
-export type OpenSocket = (
-  url: string,
-  signal?: AbortSignal,
-) => Promise<WebSocket>;
+export type OpenSocket = (url: string, signal?: AbortSignal) => Promise<WebSocket>;
 
 export const openWebSocket: OpenSocket = (url, signal) =>
   new Promise((resolve, reject) => {
     signal?.throwIfAborted();
     const socket = new WebSocket(url);
-    const timer = setTimeout(
-      () => fail(new Error("CDP connection timed out.")),
-      10_000,
-    );
+    const timer = setTimeout(() => fail(new Error("CDP connection timed out.")), 10_000);
     const cleanup = () => {
       clearTimeout(timer);
       signal?.removeEventListener("abort", abort);
@@ -31,11 +25,9 @@ export const openWebSocket: OpenSocket = (url, signal) =>
       },
       { once: true },
     );
-    socket.addEventListener(
-      "error",
-      () => fail(new Error("CDP WebSocket connection failed.")),
-      { once: true },
-    );
+    socket.addEventListener("error", () => fail(new Error("CDP WebSocket connection failed.")), {
+      once: true,
+    });
   });
 
 type Pending = {
@@ -49,9 +41,7 @@ export class CdpConnection {
   private pending = new Map<number, Pending>();
   private nextId = 0;
   private signal: AbortSignal | undefined;
-  private listeners = new Set<
-    (method: string, params: any, sessionId?: string) => void
-  >();
+  private listeners = new Set<(method: string, params: any, sessionId?: string) => void>();
   private abort = () => this.close();
   constructor(socket: WebSocket, signal?: AbortSignal) {
     this.socket = socket;
@@ -80,14 +70,9 @@ export class CdpConnection {
     this.listeners.add(listener);
   }
 
-  send<T = any>(
-    method: string,
-    params: object = {},
-    sessionId?: string,
-  ): Promise<T> {
+  send<T = any>(method: string, params: object = {}, sessionId?: string): Promise<T> {
     this.signal?.throwIfAborted();
-    if (this.socket.readyState !== 1)
-      return Promise.reject(new Error("CDP connection is closed."));
+    if (this.socket.readyState !== 1) return Promise.reject(new Error("CDP connection is closed."));
     return new Promise<T>((resolve, reject) => {
       const id = ++this.nextId;
       const timer = setTimeout(() => {
diff --git a/packages/mcp-server/src/core.ts b/packages/mcp-server/src/core.ts
index 7479fb5..bfbc13d 100644
--- a/packages/mcp-server/src/core.ts
+++ b/packages/mcp-server/src/core.ts
@@ -10,25 +10,21 @@ import { z } from "zod";
 
 import { COMMANDS } from "./browse/commands.ts";
 import { BrowserSession, type CommandRunner } from "./browse/driver.ts";
-import {
-  staticProvider,
-  type BrowserHandle,
-  type BrowserProvider,
-} from "./browse/provider.ts";
 import { PROGRAM_GUIDE, renderApiDts, renderCheatsheet } from "./browse/dts.ts";
+import { type BrowserHandle, type BrowserProvider, staticProvider } from "./browse/provider.ts";
 import type { ServerConfig } from "./config.ts";
-import { runProgram, type ProgramResult } from "./sandbox/runner.ts";
+import { type ProgramResult, runProgram } from "./sandbox/runner.ts";
 
-export { loadConfig, type ServerConfig } from "./config.ts";
+export { PROGRAM_GUIDE, renderApiDts, renderCheatsheet } from "./browse/dts.ts";
 export {
-  browserProvider,
-  staticProvider,
-  NoBrowserError,
   type BrowserHandle,
   type BrowserProvider,
+  browserProvider,
+  NoBrowserError,
+  staticProvider,
 } from "./browse/provider.ts";
 export { providerFromEnv } from "./browse/providers.ts";
-export { PROGRAM_GUIDE, renderApiDts, renderCheatsheet } from "./browse/dts.ts";
+export { loadConfig, type ServerConfig } from "./config.ts";
 export type { ProgramResult, RunLimits } from "./sandbox/runner.ts";
 
 export const INSTRUCTIONS =
@@ -157,9 +153,10 @@ export function runToolDescription(config: ServerConfig, browserLine?: string):
     `read, filter — into one program and return just the data you need. Intermediate page`,
     `content stays in the sandbox instead of entering your context.`,
     ``,
-    browserLine ?? (config.defaultCdpUrl
-      ? `Browser: the CDP endpoint at \`${config.defaultCdpUrl}\`. Pass \`cdpUrl\` to drive a different one.`
-      : "Browser: pass `cdpUrl` to reuse a browser, or omit it to create a temporary browser with the configured provider."),
+    browserLine ??
+      (config.defaultCdpUrl
+        ? `Browser: the CDP endpoint at \`${config.defaultCdpUrl}\`. Pass \`cdpUrl\` to drive a different one.`
+        : "Browser: pass `cdpUrl` to reuse a browser, or omit it to create a temporary browser with the configured provider."),
     ``,
     `Each program attaches to the browser, runs, and detaches. Page state (tabs,`,
     `cookies, scroll) belongs to that browser and persists; snapshot refs do not,`,
@@ -214,9 +211,7 @@ export async function executeBrowserRun(
 
   let lease: BrowserHandle;
   try {
-    lease = cdpUrl
-      ? { provider: "cdp", cdpUrl }
-      : await provider.create(signal ? { signal } : {});
+    lease = cdpUrl ? { provider: "cdp", cdpUrl } : await provider.create(signal ? { signal } : {});
   } catch (error) {
     return failure(describeError(error));
   }
@@ -281,11 +276,16 @@ export async function executeBrowserRun(
 /** Attach, take one JPEG of the current page, detach. Returns base64. */
 export async function captureScreenshot(
   cdpUrl: string,
-  { connect = connectOverCdp, signal }: { connect?: ToolDeps["connect"]; signal?: AbortSignal | undefined } = {},
+  {
+    connect = connectOverCdp,
+    signal,
+  }: { connect?: ToolDeps["connect"]; signal?: AbortSignal | undefined } = {},
 ): Promise<string> {
   const session = await connect({ cdpUrl, ...(signal ? { signal } : {}) });
   try {
-    const result = (await session.run("screenshot", { type: "jpeg", quality: 70 })) as { base64: string };
+    const result = (await session.run("screenshot", { type: "jpeg", quality: 70 })) as {
+      base64: string;
+    };
     return result.base64;
   } finally {
     await session.close();
diff --git a/packages/mcp-server/src/index.ts b/packages/mcp-server/src/index.ts
index e48de37..c065cea 100644
--- a/packages/mcp-server/src/index.ts
+++ b/packages/mcp-server/src/index.ts
@@ -6,8 +6,8 @@
 import { serve } from "@hono/node-server";
 
 import { createApp } from "./app.ts";
-import { loadConfig } from "./config.ts";
 import { providerFromEnv } from "./browse/providers.ts";
+import { loadConfig } from "./config.ts";
 
 const command = process.argv[2];
 if (command && command !== "dev" && command !== "serve") {
@@ -17,9 +17,7 @@ if (command && command !== "dev" && command !== "serve") {
 // Local process ownership is confined to CLI dev, never the fetch application.
 const startup = new AbortController();
 let local: import("./node/local-browser.ts").LocalBrowser | undefined;
-let starting:
-  | Promise<import("./node/local-browser.ts").LocalBrowser>
-  | undefined;
+let starting: Promise<import("./node/local-browser.ts").LocalBrowser> | undefined;
 let stopping = false;
 const stop = async () => {
   if (stopping) return;
@@ -66,22 +64,17 @@ try {
     }),
   });
 
-  server = serve(
-    { fetch: app.fetch, hostname: config.host, port: config.port },
-    (info) => {
-      log(`listening on http://${config.host}:${info.port}${config.endpoint}`);
-      log(
-        config.defaultCdpUrl
-          ? `default browser: ${config.defaultCdpUrl}`
-          : "no BROWSE_CDP_URL set: callers must pass cdpUrl per request",
-      );
-      if (!config.authToken) {
-        log(
-          "no MCP_AUTH_TOKEN set: every caller on this host can drive the browser",
-        );
-      }
-    },
-  );
+  server = serve({ fetch: app.fetch, hostname: config.host, port: config.port }, (info) => {
+    log(`listening on http://${config.host}:${info.port}${config.endpoint}`);
+    log(
+      config.defaultCdpUrl
+        ? `default browser: ${config.defaultCdpUrl}`
+        : "no BROWSE_CDP_URL set: callers must pass cdpUrl per request",
+    );
+    if (!config.authToken) {
+      log("no MCP_AUTH_TOKEN set: every caller on this host can drive the browser");
+    }
+  });
 
   server.on("error", async (error) => {
     console.error(error);
diff --git a/packages/mcp-server/src/mcp/server.ts b/packages/mcp-server/src/mcp/server.ts
index 221686c..f5f96a7 100644
--- a/packages/mcp-server/src/mcp/server.ts
+++ b/packages/mcp-server/src/mcp/server.ts
@@ -11,20 +11,19 @@
  */
 
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
-
+import { renderApiDts } from "../browse/dts.ts";
 import {
   API_TOOL_DESCRIPTION,
-  INSTRUCTIONS,
   executeBrowserRun,
+  INSTRUCTIONS,
   renderBrowserApi,
   renderGuide,
   runInputShape,
   runToolDescription,
   type ToolDeps,
 } from "../core.ts";
-import { renderApiDts } from "../browse/dts.ts";
 
-export { EXAMPLE_PROGRAM, type Connection } from "../core.ts";
+export { type Connection, EXAMPLE_PROGRAM } from "../core.ts";
 
 export const SERVER_NAME = "browse-code-mode";
 export const SERVER_VERSION = "0.1.0";
diff --git a/packages/mcp-server/src/node/local-browser.ts b/packages/mcp-server/src/node/local-browser.ts
index 3ec7d47..47a05c0 100644
--- a/packages/mcp-server/src/node/local-browser.ts
+++ b/packages/mcp-server/src/node/local-browser.ts
@@ -1,9 +1,9 @@
 /** Node-only dev lifecycle. Never import this from a deployed fetch handler. */
-import { spawn, type ChildProcess } from "node:child_process";
+import { type ChildProcess, spawn } from "node:child_process";
 import { existsSync } from "node:fs";
 import { mkdtemp, rm } from "node:fs/promises";
-import { tmpdir } from "node:os";
 import { createServer } from "node:net";
+import { tmpdir } from "node:os";
 import { join } from "node:path";
 import type { BrowserHandle, BrowserProvider } from "../browse/provider.ts";
 
@@ -29,11 +29,7 @@ function findChrome(): string {
         ]
       : process.platform === "win32"
         ? ["C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe"]
-        : [
-            "/usr/bin/google-chrome",
-            "/usr/bin/chromium",
-            "/usr/bin/chromium-browser",
-          ];
+        : ["/usr/bin/google-chrome", "/usr/bin/chromium", "/usr/bin/chromium-browser"];
   const executable = candidates.find(existsSync);
   if (!executable) throw new Error("Chrome not found. Set CHROME_PATH.");
   return executable;
@@ -55,17 +51,14 @@ export async function createLocalBrowser({
   headless?: boolean;
   signal?: AbortSignal;
 } = {}): Promise<LocalBrowser> {
-  if (!Number.isInteger(port) || port < 1 || port > 65535)
-    throw new Error("Invalid CHROME_PORT.");
+  if (!Number.isInteger(port) || port < 1 || port > 65535) throw new Error("Invalid CHROME_PORT.");
   signal?.throwIfAborted();
   const browser = { provider: "cdp", cdpUrl: String(port) };
-  if (await cdpReady(port))
-    return { browser, owned: false, async shutdown() {} };
+  if (await cdpReady(port)) return { browser, owned: false, async shutdown() {} };
   const executable = findChrome();
   const temporary = !process.env.CHROME_USER_DATA_DIR;
   const profile =
-    process.env.CHROME_USER_DATA_DIR ??
-    (await mkdtemp(join(tmpdir(), "browse-cdp-")));
+    process.env.CHROME_USER_DATA_DIR ?? (await mkdtemp(join(tmpdir(), "browse-cdp-")));
   const child = spawn(
     executable,
     [
@@ -91,11 +84,7 @@ export async function createLocalBrowser({
   let shutdownPromise: Promise<void> | undefined;
   const shutdown = (): Promise<void> =>
     (shutdownPromise ??= (async () => {
-      if (
-        child.exitCode === null &&
-        child.signalCode === null &&
-        !launchError
-      ) {
+      if (child.exitCode === null && child.signalCode === null && !launchError) {
         child.kill("SIGTERM");
         const timer = setTimeout(() => child.kill("SIGKILL"), 3000);
         await exited;
@@ -111,8 +100,7 @@ export async function createLocalBrowser({
       if (launchError) throw launchError;
       if (child.exitCode !== null || child.signalCode !== null)
         throw new Error("Chrome exited before CDP was ready.");
-      if (await cdpReady(port))
-        return { browser, owned: true, process: child, shutdown };
+      if (await cdpReady(port)) return { browser, owned: true, process: child, shutdown };
       await new Promise((resolve) => setTimeout(resolve, 150));
     }
     throw new Error(`Chrome did not expose CDP on ${port}.`);
@@ -132,13 +120,20 @@ export async function createLocalBrowser({
 export function localProvider({
   port = Number(process.env.CHROME_PORT ?? 9222),
   headless = process.env.CHROME_HEADLESS !== "0",
-}: { port?: number; headless?: boolean } = {}): BrowserProvider {
+}: {
+  port?: number;
+  headless?: boolean;
+} = {}): BrowserProvider {
   const running = new Map<string, LocalBrowser>();
   return {
     name: "local",
     async create({ signal } = {}) {
       const target = running.has(String(port)) ? await freePort() : port;
-      const local = await createLocalBrowser({ port: target, headless, ...(signal ? { signal } : {}) });
+      const local = await createLocalBrowser({
+        port: target,
+        headless,
+        ...(signal ? { signal } : {}),
+      });
       running.set(local.browser.cdpUrl, local);
       return { provider: "local", cdpUrl: local.browser.cdpUrl, sessionId: local.browser.cdpUrl };
     },
diff --git a/packages/mcp-server/src/runtime-bundled.ts b/packages/mcp-server/src/runtime-bundled.ts
index 0cf5d76..3d5191a 100644
--- a/packages/mcp-server/src/runtime-bundled.ts
+++ b/packages/mcp-server/src/runtime-bundled.ts
@@ -1,15 +1,22 @@
-import { newVariant, newQuickJSWASMModuleFromVariant } from "quickjs-emscripten-core";
-import variant from "@jitl/quickjs-wasmfile-release-sync";
 import wasmBinary from "virtual:browse-wasm";
+import variant from "@jitl/quickjs-wasmfile-release-sync";
+import { newQuickJSWASMModuleFromVariant, newVariant } from "quickjs-emscripten-core";
 import { createApp } from "./app.ts";
-import { loadConfig } from "./config.ts";
 import { providerFromEnv } from "./browse/providers.ts";
+import { loadConfig } from "./config.ts";
 import { createProgramRunner } from "./sandbox/runner.ts";
 
-const run = createProgramRunner(() => newQuickJSWASMModuleFromVariant(newVariant(
-  variant as unknown as Exclude<Awaited<Parameters<typeof newQuickJSWASMModuleFromVariant>[0]>, { default: unknown }>,
-  { wasmBinary },
-)));
+const run = createProgramRunner(() =>
+  newQuickJSWASMModuleFromVariant(
+    newVariant(
+      variant as unknown as Exclude<
+        Awaited<Parameters<typeof newQuickJSWASMModuleFromVariant>[0]>,
+        { default: unknown }
+      >,
+      { wasmBinary },
+    ),
+  ),
+);
 
 export function createConfiguredApp(env: Record<string, string | undefined>) {
   return createApp({ config: loadConfig(env), provider: providerFromEnv(env), run });
diff --git a/packages/mcp-server/src/runtime.ts b/packages/mcp-server/src/runtime.ts
index 183341f..e12aeb5 100644
--- a/packages/mcp-server/src/runtime.ts
+++ b/packages/mcp-server/src/runtime.ts
@@ -1,6 +1,6 @@
 import { createApp } from "./app.ts";
-import { loadConfig } from "./config.ts";
 import { providerFromEnv } from "./browse/providers.ts";
+import { loadConfig } from "./config.ts";
 
 export function createConfiguredApp(env: Record<string, string | undefined>) {
   return createApp({ config: loadConfig(env), provider: providerFromEnv(env) });
diff --git a/packages/mcp-server/src/sandbox/runner.ts b/packages/mcp-server/src/sandbox/runner.ts
index 5c3c078..cb5bd4f 100644
--- a/packages/mcp-server/src/sandbox/runner.ts
+++ b/packages/mcp-server/src/sandbox/runner.ts
@@ -1,18 +1,16 @@
 /** QuickJS/WASM sandbox shared by Node, Vercel and Cloudflare Workers.
  * Only JSON values cross the boundary; the guest has no host globals. */
+
+import variant from "@jitl/quickjs-wasmfile-release-sync";
 import {
   newQuickJSWASMModuleFromVariant,
-  type QuickJSWASMModule,
-  type QuickJSHandle,
   type QuickJSDeferredPromise,
+  type QuickJSHandle,
+  type QuickJSWASMModule,
 } from "quickjs-emscripten-core";
-import variant from "@jitl/quickjs-wasmfile-release-sync";
 import { transform } from "sucrase";
 import type { CommandRunner } from "../browse/driver.ts";
-import {
-  createHostFunctions,
-  type CommandCall,
-} from "../browse/host-functions.ts";
+import { type CommandCall, createHostFunctions } from "../browse/host-functions.ts";
 export interface RunLimits {
   timeoutMs?: number;
   maxBridgeRequests?: number;
@@ -68,8 +66,7 @@ const loadQuickJS: LoadQuickJS = () =>
     variant as unknown as Parameters<typeof newQuickJSWASMModuleFromVariant>[0],
   );
 
-export const runProgram = (options: RunProgramOptions) =>
-  createProgramRunner(loadQuickJS)(options);
+export const runProgram = (options: RunProgramOptions) => createProgramRunner(loadQuickJS)(options);
 
 export function createProgramRunner(load: LoadQuickJS) {
   return async (options: RunProgramOptions): Promise<ProgramResult> => {
@@ -89,9 +86,7 @@ export function createProgramRunner(load: LoadQuickJS) {
     });
     const module = await load();
     const runtime = module.newRuntime();
-    runtime.setMemoryLimit(
-      options.limits?.memoryLimitBytes ?? 32 * 1024 * 1024,
-    );
+    runtime.setMemoryLimit(options.limits?.memoryLimitBytes ?? 32 * 1024 * 1024);
     runtime.setMaxStackSize(512 * 1024);
     let interrupts = 0;
     let budgetExceeded = false;
@@ -99,9 +94,7 @@ export function createProgramRunner(load: LoadQuickJS) {
     // bounds synchronous loops there, without needing a worker thread.
     runtime.setInterruptHandler(() => {
       budgetExceeded = ++interrupts > (options.limits?.maxInterrupts ?? 10_000);
-      return (
-        budgetExceeded || Date.now() >= deadline || !!options.signal?.aborted
-      );
+      return budgetExceeded || Date.now() >= deadline || !!options.signal?.aborted;
     });
     const vm = runtime.newContext();
     let alive = true;
@@ -115,67 +108,57 @@ export function createProgramRunner(load: LoadQuickJS) {
         throw new Error("Result exceeds maxResultBytes.");
       return vm.newString(json);
     };
-    const host = vm.newFunction(
-      "__host",
-      (groupHandle, fnHandle, argsHandle) => {
-        const group = vm.getString(groupHandle);
-        const fn = vm.getString(fnHandle);
-        const functions = Object.hasOwn(hostFunctions, group)
-          ? hostFunctions[group]
-          : undefined;
-        const callback =
-          functions && Object.hasOwn(functions, fn) ? functions[fn] : undefined;
-        if (!callback)
-          return {
-            error: vm.newError(`Unknown host function: ${group}.${fn}`),
-          };
-        if (++commands > maxCommands)
-          return { error: vm.newError("Command budget exceeded.") };
-        const args = JSON.parse(vm.getString(argsHandle)) as unknown[];
-        const deferred = vm.newPromise();
-        deferreds.add(deferred);
-        const task = Promise.resolve()
-          .then(() => {
-            if (alive) return callback(...args);
-          })
-          .then(
-            (value) => {
-              if (!alive) return;
-              const handle = encode(value);
-              deferred.resolve(handle);
-              handle.dispose();
-            },
-            () => {
-              if (!alive) return;
-              const error = vm.newError("Host function failed.");
-              deferred.reject(error);
-              error.dispose();
-            },
-          )
-          .catch((error) => {
+    const host = vm.newFunction("__host", (groupHandle, fnHandle, argsHandle) => {
+      const group = vm.getString(groupHandle);
+      const fn = vm.getString(fnHandle);
+      const functions = Object.hasOwn(hostFunctions, group) ? hostFunctions[group] : undefined;
+      const callback = functions && Object.hasOwn(functions, fn) ? functions[fn] : undefined;
+      if (!callback)
+        return {
+          error: vm.newError(`Unknown host function: ${group}.${fn}`),
+        };
+      if (++commands > maxCommands) return { error: vm.newError("Command budget exceeded.") };
+      const args = JSON.parse(vm.getString(argsHandle)) as unknown[];
+      const deferred = vm.newPromise();
+      deferreds.add(deferred);
+      const task = Promise.resolve()
+        .then(() => {
+          if (alive) return callback(...args);
+        })
+        .then(
+          (value) => {
             if (!alive) return;
-            const handle = vm.newError(
-              error instanceof Error ? error.message : String(error),
-            );
-            deferred.reject(handle);
+            const handle = encode(value);
+            deferred.resolve(handle);
             handle.dispose();
-          })
-          .finally(() => {
-            pending.delete(task);
-            if (alive) {
-              deferred.dispose();
-              deferreds.delete(deferred);
-            }
-          });
-        pending.add(task);
-        return deferred.handle;
-      },
-    );
+          },
+          () => {
+            if (!alive) return;
+            const error = vm.newError("Host function failed.");
+            deferred.reject(error);
+            error.dispose();
+          },
+        )
+        .catch((error) => {
+          if (!alive) return;
+          const handle = vm.newError(error instanceof Error ? error.message : String(error));
+          deferred.reject(handle);
+          handle.dispose();
+        })
+        .finally(() => {
+          pending.delete(task);
+          if (alive) {
+            deferred.dispose();
+            deferreds.delete(deferred);
+          }
+        });
+      pending.add(task);
+      return deferred.handle;
+    });
     const log = vm.newFunction("__log", (levelHandle, argsHandle) => {
       const json = vm.getString(argsHandle);
       logBytes += new TextEncoder().encode(json).byteLength;
-      if (logBytes > maxBytes)
-        return { error: vm.newError("Log output exceeds maxResultBytes.") };
+      if (logBytes > maxBytes) return { error: vm.newError("Log output exceeds maxResultBytes.") };
       const entry = {
         level: vm.getString(levelHandle) as LogEntry["level"],
         args: JSON.parse(json) as unknown[],
@@ -192,10 +175,10 @@ export function createProgramRunner(load: LoadQuickJS) {
     let abort: (() => void) | undefined;
     try {
       options.signal?.throwIfAborted();
-      const source = transform(
-        `async function __program() {\n${options.code}\n}\n__program()`,
-        { transforms: ["typescript"], filePath: "program.ts" },
-      ).code;
+      const source = transform(`async function __program() {\n${options.code}\n}\n__program()`, {
+        transforms: ["typescript"],
+        filePath: "program.ts",
+      }).code;
       const setup = vm.evalCode(`
         for (const group of ["browse", "mouse", "tab"]) {
           globalThis[group] = new Proxy({}, { get(_, fn) {
@@ -216,8 +199,7 @@ export function createProgramRunner(load: LoadQuickJS) {
             ),
           Math.max(1, deadline - Date.now()),
         );
-        abort = () =>
-          reject(options.signal?.reason ?? new Error("Program aborted."));
+        abort = () => reject(options.signal?.reason ?? new Error("Program aborted."));
         options.signal?.addEventListener("abort", abort, { once: true });
       });
       while (true) {
@@ -232,10 +214,7 @@ export function createProgramRunner(load: LoadQuickJS) {
         if (state.type === "fulfilled") {
           const value = vm.dump(state.value);
           state.value.dispose();
-          if (pending.size)
-            throw new Error(
-              "Program returned with unawaited browser commands.",
-            );
+          if (pending.size) throw new Error("Program returned with unawaited browser commands.");
           const check = encode(value);
           check.dispose();
           return {
@@ -253,8 +232,7 @@ export function createProgramRunner(load: LoadQuickJS) {
             name: detail.name ?? "Error",
           });
         }
-        if (!pending.size)
-          throw new Error("Program left an unresolved promise.");
+        if (!pending.size) throw new Error("Program left an unresolved promise.");
         await Promise.race([stopped, ...pending]);
       }
     } catch (error) {
@@ -263,11 +241,7 @@ export function createProgramRunner(load: LoadQuickJS) {
       return {
         status: "failed",
         error: {
-          name: timedOut
-            ? "RunTimeoutError"
-            : error instanceof Error
-              ? error.name
-              : "Error",
+          name: timedOut ? "RunTimeoutError" : error instanceof Error ? error.name : "Error",
           message: timedOut
             ? "Program exceeded its time or instruction budget."
             : error instanceof Error
diff --git a/packages/mcp-server/src/worker.ts b/packages/mcp-server/src/worker.ts
index aaf644b..f939149 100644
--- a/packages/mcp-server/src/worker.ts
+++ b/packages/mcp-server/src/worker.ts
@@ -1,15 +1,12 @@
-import {
-  newVariant,
-  newQuickJSWASMModuleFromVariant,
-} from "quickjs-emscripten-core";
 import variant from "@jitl/quickjs-wasmfile-release-sync";
+import { newQuickJSWASMModuleFromVariant, newVariant } from "quickjs-emscripten-core";
 import wasmModule from "../node_modules/@jitl/quickjs-wasmfile-release-sync/dist/emscripten-module.wasm";
 import { createApp } from "./app.ts";
-import { loadConfig } from "./config.ts";
 import { BrowserSession } from "./browse/driver.ts";
-import { createProgramRunner } from "./sandbox/runner.ts";
-import type { OpenSocket } from "./browse/transport.ts";
 import { providerFromEnv } from "./browse/providers.ts";
+import type { OpenSocket } from "./browse/transport.ts";
+import { loadConfig } from "./config.ts";
+import { createProgramRunner } from "./sandbox/runner.ts";
 
 const run = createProgramRunner(() =>
   newQuickJSWASMModuleFromVariant(
@@ -35,12 +32,12 @@ const openSocket: OpenSocket = async (url, signal) => {
 };
 
 export function createConfiguredApp(env: Record<string, string | undefined>) {
-    return createApp({
-      config: loadConfig({ ...env }),
-      run,
-      provider: providerFromEnv({ ...env }),
-      connect: (options) => BrowserSession.connect({ ...options, openSocket }),
-    });
+  return createApp({
+    config: loadConfig({ ...env }),
+    run,
+    provider: providerFromEnv({ ...env }),
+    connect: (options) => BrowserSession.connect({ ...options, openSocket }),
+  });
 }
 
 export default {
diff --git a/packages/mcp-server/tests/browser.e2e.test.ts b/packages/mcp-server/tests/browser.e2e.test.ts
index 7713d2f..60ff8ac 100644
--- a/packages/mcp-server/tests/browser.e2e.test.ts
+++ b/packages/mcp-server/tests/browser.e2e.test.ts
@@ -11,7 +11,7 @@ import assert from "node:assert/strict";
 import { test } from "node:test";
 
 import { BrowserSession } from "../src/browse/driver.ts";
-import { runProgram, type ProgramResult } from "../src/sandbox/runner.ts";
+import { type ProgramResult, runProgram } from "../src/sandbox/runner.ts";
 
 const enabled = process.env.BROWSE_E2E === "1";
 const CDP_URL = process.env.BROWSE_CDP_URL ?? "9222";
@@ -26,7 +26,9 @@ async function run(code: string): Promise<ProgramResult> {
   }
 }
 
-test("a program drives a real browser and returns only its result", { skip: !enabled }, async () => {
+test("a program drives a real browser and returns only its result", {
+  skip: !enabled,
+}, async () => {
   const result = await run(`
     await browse.open("https://example.com");
     const { tree } = await browse.snapshot();
diff --git a/packages/mcp-server/tests/commands.test.ts b/packages/mcp-server/tests/commands.test.ts
index de7fb83..b82b167 100644
--- a/packages/mcp-server/tests/commands.test.ts
+++ b/packages/mcp-server/tests/commands.test.ts
@@ -1,14 +1,9 @@
 import assert from "node:assert/strict";
 import { test } from "node:test";
 
-import {
-  buildParams,
-  COMMANDS,
-  findCommand,
-  WIRE_COMMANDS,
-} from "../src/browse/commands.ts";
-import { formatCall } from "../src/browse/host-functions.ts";
+import { buildParams, COMMANDS, findCommand, WIRE_COMMANDS } from "../src/browse/commands.ts";
 import { renderApiDts, renderCheatsheet } from "../src/browse/dts.ts";
+import { formatCall } from "../src/browse/host-functions.ts";
 
 test("every driver command is reachable from the sandbox", () => {
   const wired = new Set(COMMANDS.map((spec) => spec.wire));
@@ -93,7 +88,12 @@ test("optional arguments may be omitted", () => {
 test("calls render as the shell command they stand for", () => {
   const cases: Array<[string, string, unknown[], string]> = [
     ["browse", "click", ["@0-12"], "browse click @0-12"],
-    ["browse", "fill", ["#q", "hi there", { pressEnter: true }], 'browse fill #q "hi there" --press-enter'],
+    [
+      "browse",
+      "fill",
+      ["#q", "hi there", { pressEnter: true }],
+      'browse fill #q "hi there" --press-enter',
+    ],
     ["browse", "snapshot", [{ maxDepth: 4 }], "browse snapshot --max-depth 4"],
     ["mouse", "scroll", [10, 20, 0, 600], "browse mouse scroll 10 20 0 600"],
     ["tab", "list", [], "browse tab list"],
diff --git a/packages/mcp-server/tests/frames.e2e.test.ts b/packages/mcp-server/tests/frames.e2e.test.ts
index 8693ca4..2170fa1 100644
--- a/packages/mcp-server/tests/frames.e2e.test.ts
+++ b/packages/mcp-server/tests/frames.e2e.test.ts
@@ -10,8 +10,8 @@ import assert from "node:assert/strict";
 import { after, before, test } from "node:test";
 
 import { BrowserSession } from "../src/browse/driver.ts";
-import { runProgram, type ProgramResult } from "../src/sandbox/runner.ts";
-import { serveHardPages, type HardPages } from "./helpers/hard-pages.ts";
+import { type ProgramResult, runProgram } from "../src/sandbox/runner.ts";
+import { type HardPages, serveHardPages } from "./helpers/hard-pages.ts";
 
 const enabled = process.env.BROWSE_E2E === "1";
 const CDP_URL = process.env.BROWSE_CDP_URL ?? "9222";
@@ -55,9 +55,12 @@ async function onHardPage(body: string): Promise<unknown> {
   return result.value;
 }
 
-test("the snapshot includes every frame, cross-site and nested ones too", { skip: !enabled }, async () => {
+test("the snapshot includes every frame, cross-site and nested ones too", {
+  skip: !enabled,
+}, async () => {
   const tree = (await onHardPage(`return tree;`)) as string;
-  const refOf = (name: string) => /\[(\d+)-\d+\]/.exec(tree.split("\n").find((l) => l.includes(name)) ?? "")?.[1];
+  const refOf = (name: string) =>
+    /\[(\d+)-\d+\]/.exec(tree.split("\n").find((l) => l.includes(name)) ?? "")?.[1];
 
   for (const name of [
     "Top button",
@@ -67,12 +70,20 @@ test("the snapshot includes every frame, cross-site and nested ones too", { skip
     "Button in shadow frame",
     "Open shadow button",
     "Closed shadow button",
-  ]) assert.ok(refOf(name) !== undefined, `${name} missing from:\n${tree}`);
+  ])
+    assert.ok(refOf(name) !== undefined, `${name} missing from:\n${tree}`);
 
   // The frame index in a ref says which document the element belongs to.
   assert.equal(refOf("Top button"), "0");
   assert.equal(refOf("Open shadow button"), "0");
-  const frames = new Set(["Same-origin button", "Cross-site button", "Nested frame button", "Button in shadow frame"].map(refOf));
+  const frames = new Set(
+    [
+      "Same-origin button",
+      "Cross-site button",
+      "Nested frame button",
+      "Button in shadow frame",
+    ].map(refOf),
+  );
   assert.equal(frames.size, 4);
   assert.ok(![...frames].includes("0"));
 
@@ -103,7 +114,9 @@ test("refs click inside every frame and shadow root", { skip: !enabled }, async
   ]);
 });
 
-test("fill, select, read, and type work in cross-site and same-origin frames", { skip: !enabled }, async () => {
+test("fill, select, read, and type work in cross-site and same-origin frames", {
+  skip: !enabled,
+}, async () => {
   const value = await onHardPage(`
     await browse.fill(ref("Cross-site input"), "filled");
     await browse.select(ref("Same-origin select"), ["b"]);
@@ -122,7 +135,12 @@ test("fill, select, read, and type work in cross-site and same-origin frames", {
     crossText: "Text inside the cross-site frame",
     crossValue: "filled",
     typed: "typed",
-    events: ["change:cross-input=filled", "change:same-select=b", "change:cross-input=", "click:cross-input"],
+    events: [
+      "change:cross-input=filled",
+      "change:same-select=b",
+      "change:cross-input=",
+      "click:cross-input",
+    ],
   });
 });
 
@@ -144,7 +162,9 @@ test("CSS pierces open shadow roots and hops into frames with >>", { skip: !enab
   });
 });
 
-test("get box returns page coordinates that mouse.click can use, even in a nested cross-site frame", { skip: !enabled }, async () => {
+test("get box returns page coordinates that mouse.click can use, even in a nested cross-site frame", {
+  skip: !enabled,
+}, async () => {
   const events = await onHardPage(`
     const { x, y } = await browse.get("box", ref("Nested frame button"));
     await mouse.click(x, y);
diff --git a/packages/mcp-server/tests/lifecycle.test.ts b/packages/mcp-server/tests/lifecycle.test.ts
index a76df58..e957132 100644
--- a/packages/mcp-server/tests/lifecycle.test.ts
+++ b/packages/mcp-server/tests/lifecycle.test.ts
@@ -1,11 +1,11 @@
 import assert from "node:assert/strict";
 import { test } from "node:test";
+import { Client } from "@modelcontextprotocol/sdk/client/index.js";
+import { InMemoryTransport } from "@modelcontextprotocol/sdk/inMemory.js";
 import { createApp } from "../src/app.ts";
-import { loadConfig } from "../src/config.ts";
 import { browserProvider, staticProvider } from "../src/browse/provider.ts";
 import { providerFromEnv } from "../src/browse/providers.ts";
-import { Client } from "@modelcontextprotocol/sdk/client/index.js";
-import { InMemoryTransport } from "@modelcontextprotocol/sdk/inMemory.js";
+import { loadConfig } from "../src/config.ts";
 import { createMcpServer } from "../src/mcp/server.ts";
 
 test("provider shutdown still runs when CDP disconnect throws", async () => {
@@ -13,10 +13,18 @@ test("provider shutdown still runs when CDP disconnect throws", async () => {
   const server = createMcpServer({
     config: loadConfig(),
     provider: browserProvider({
-      name: "test", create: async () => ({ cdpUrl: "wss://example.test" }),
-      shutdown: async () => { stopped = true; },
+      name: "test",
+      create: async () => ({ cdpUrl: "wss://example.test" }),
+      shutdown: async () => {
+        stopped = true;
+      },
+    }),
+    connect: async () => ({
+      run: async () => null,
+      close: async () => {
+        throw new Error("disconnect failed");
+      },
     }),
-    connect: async () => ({ run: async () => null, close: async () => { throw new Error("disconnect failed"); } }),
   });
   const client = new Client({ name: "cleanup-test", version: "1" });
   const [clientTransport, serverTransport] = InMemoryTransport.createLinkedPair();
@@ -26,7 +34,10 @@ test("provider shutdown still runs when CDP disconnect throws", async () => {
     const result = await client.callTool({ name: "browser_run", arguments: { code: "return 1;" } });
     assert.equal(result.isError, true);
     assert.equal(stopped, true);
-  } finally { await client.close(); await server.close(); }
+  } finally {
+    await client.close();
+    await server.close();
+  }
 });
 
 test("a serialized handle can be shut down on a fresh instance", async () => {
@@ -43,9 +54,7 @@ test("a serialized handle can be shut down on a fresh instance", async () => {
       },
     });
   const create = createApp({ config: loadConfig(), provider: provider() });
-  const result = await create.fetch(
-    new Request("http://test/browser", { method: "POST" }),
-  );
+  const result = await create.fetch(new Request("http://test/browser", { method: "POST" }));
   assert.equal(result.status, 201);
   const handle = await result.json();
   const fresh = createApp({ config: loadConfig(), provider: provider() });
@@ -101,9 +110,7 @@ for (const name of ["kernel", "browserbase"]) {
     const body = JSON.parse(String(calls[0]?.init?.body));
     assert.equal(name === "kernel" ? body.timeout_seconds : body.timeout, 600);
     if (name === "browserbase") assert.equal(body.keepAlive, true);
-    await providerFromEnv(env, request).shutdown(
-      JSON.parse(JSON.stringify(handle)),
-    );
+    await providerFromEnv(env, request).shutdown(JSON.parse(JSON.stringify(handle)));
     assert.match(calls[1]!.url, /\/one$/);
     assert.equal(calls[1]?.init?.method, name === "kernel" ? "DELETE" : "POST");
   });
diff --git a/packages/mcp-server/tests/mcp.test.ts b/packages/mcp-server/tests/mcp.test.ts
index b200632..8369484 100644
--- a/packages/mcp-server/tests/mcp.test.ts
+++ b/packages/mcp-server/tests/mcp.test.ts
@@ -8,7 +8,12 @@ import { LoggingMessageNotificationSchema } from "@modelcontextprotocol/sdk/type
 
 import { createApp } from "../src/app.ts";
 import { loadConfig } from "../src/config.ts";
-import { createFakeBrowser, echoHandler, type FakeBrowser, type FakeHandler } from "./helpers/fake-browser.ts";
+import {
+  createFakeBrowser,
+  echoHandler,
+  type FakeBrowser,
+  type FakeHandler,
+} from "./helpers/fake-browser.ts";
 
 const cleanups: Array<() => Promise<void>> = [];
 
@@ -81,10 +86,10 @@ test("the server advertises exactly the code mode surface", async () => {
   assert.ok(run?.inputSchema.properties && "cdpUrl" in run.inputSchema.properties);
 
   const { resources } = await client.listResources();
-  assert.deepEqual(
-    resources.map((resource) => resource.uri).sort(),
-    ["browse://api.d.ts", "browse://guide.md"],
-  );
+  assert.deepEqual(resources.map((resource) => resource.uri).sort(), [
+    "browse://api.d.ts",
+    "browse://guide.md",
+  ]);
 });
 
 test("the transport is stateless: no session id is issued", async () => {
@@ -227,7 +232,9 @@ test("a provider supplies the browser and is released after the program", async
           liveViewUrl: `https://cloud.example/watch/${sessionId}`,
         };
       },
-      async shutdown(browser) { released.push(browser.sessionId!); },
+      async shutdown(browser) {
+        released.push(browser.sessionId!);
+      },
     },
     connect: async () => createFakeBrowser(),
   });
@@ -253,7 +260,10 @@ test("a provider supplies the browser and is released after the program", async
   });
 
   assert.equal(result.isError, false);
-  assert.equal((result.structuredContent as { cdpUrl: string }).cdpUrl, "wss://cloud.example/session-1");
+  assert.equal(
+    (result.structuredContent as { cdpUrl: string }).cdpUrl,
+    "wss://cloud.example/session-1",
+  );
   assert.deepEqual(acquired, ["session-1"]);
   assert.deepEqual(released, ["session-1"], "the session must be ended, not orphaned");
 
diff --git a/packages/mcp-server/tests/runtime.e2e.test.ts b/packages/mcp-server/tests/runtime.e2e.test.ts
index f4851db..11e4fff 100644
--- a/packages/mcp-server/tests/runtime.e2e.test.ts
+++ b/packages/mcp-server/tests/runtime.e2e.test.ts
@@ -4,7 +4,7 @@ import { createServer } from "node:net";
 import { test } from "node:test";
 import { Client } from "@modelcontextprotocol/sdk/client/index.js";
 import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
-import { createLocalBrowser, cdpReady } from "../src/node/local-browser.ts";
+import { cdpReady, createLocalBrowser } from "../src/node/local-browser.ts";
 
 async function freePort(): Promise<number> {
   const server = createServer();
@@ -15,74 +15,61 @@ async function freePort(): Promise<number> {
   return address.port;
 }
 
-test(
-  "deployed runtime executes a program and leaves borrowed Chrome alive",
-  { timeout: 90_000 },
-  async () => {
-    const chromePort = await freePort();
-    const port = await freePort();
-    const local = await createLocalBrowser({ port: chromePort });
-    const worker = process.env.BROWSE_RUNTIME === "worker";
-    const child = spawn(
-      worker ? "pnpm" : process.execPath,
-      worker
-        ? [
-            "exec",
-            "wrangler",
-            "dev",
-            "--port",
-            String(port),
-            "--var",
-            `BROWSE_CDP_URL:${chromePort}`,
-          ]
-        : ["src/index.ts", "dev"],
-      {
-        cwd: new URL("..", import.meta.url),
-        env: {
-          ...process.env,
-          PORT: String(port),
-          CHROME_PORT: String(chromePort),
-          MCP_AUTH_TOKEN: "",
-          BROWSE_PROVIDER: "cdp",
-        },
-        stdio: "pipe",
-        detached: process.platform !== "win32",
+test("deployed runtime executes a program and leaves borrowed Chrome alive", {
+  timeout: 90_000,
+}, async () => {
+  const chromePort = await freePort();
+  const port = await freePort();
+  const local = await createLocalBrowser({ port: chromePort });
+  const worker = process.env.BROWSE_RUNTIME === "worker";
+  const child = spawn(
+    worker ? "pnpm" : process.execPath,
+    worker
+      ? ["exec", "wrangler", "dev", "--port", String(port), "--var", `BROWSE_CDP_URL:${chromePort}`]
+      : ["src/index.ts", "dev"],
+    {
+      cwd: new URL("..", import.meta.url),
+      env: {
+        ...process.env,
+        PORT: String(port),
+        CHROME_PORT: String(chromePort),
+        MCP_AUTH_TOKEN: "",
+        BROWSE_PROVIDER: "cdp",
       },
-    );
-    let output = "";
-    child.stdout.on("data", (data) => {
-      output += data;
-    });
-    child.stderr.on("data", (data) => {
-      output += data;
-    });
-    const exit = new Promise<void>((resolve) =>
-      child.once("exit", () => resolve()),
-    );
-    const client = new Client({ name: "runtime-test", version: "1" });
-    const base = `http://127.0.0.1:${port}`;
-    try {
-      const deadline = Date.now() + 30_000;
-      while (true) {
-        if (Date.now() >= deadline || child.exitCode !== null)
-          throw new Error(`Runtime did not start: ${output}`);
-        try {
-          if ((await fetch(`${base}/health`)).ok) break;
-        } catch {}
-        await new Promise((resolve) => setTimeout(resolve, 100));
-      }
-      const create = await fetch(`${base}/browser`, { method: "POST" });
-      assert.equal(create.status, 201);
-      const browser = (await create.json()) as { cdpUrl: string };
-      await client.connect(
-        new StreamableHTTPClientTransport(new URL(`${base}/mcp`)),
-      );
-      const call = (code: string) =>
-        client.callTool({
-          name: "browser_run",
-          arguments: { code, cdpUrl: browser.cdpUrl },
-        });
-      const result = await call(`
+      stdio: "pipe",
+      detached: process.platform !== "win32",
+    },
+  );
+  let output = "";
+  child.stdout.on("data", (data) => {
+    output += data;
+  });
+  child.stderr.on("data", (data) => {
+    output += data;
+  });
+  const exit = new Promise<void>((resolve) => child.once("exit", () => resolve()));
+  const client = new Client({ name: "runtime-test", version: "1" });
+  const base = `http://127.0.0.1:${port}`;
+  try {
+    const deadline = Date.now() + 30_000;
+    while (true) {
+      if (Date.now() >= deadline || child.exitCode !== null)
+        throw new Error(`Runtime did not start: ${output}`);
+      try {
+        if ((await fetch(`${base}/health`)).ok) break;
+      } catch {}
+      await new Promise((resolve) => setTimeout(resolve, 100));
+    }
+    const create = await fetch(`${base}/browser`, { method: "POST" });
+    assert.equal(create.status, 201);
+    const browser = (await create.json()) as { cdpUrl: string };
+    await client.connect(new StreamableHTTPClientTransport(new URL(`${base}/mcp`)));
+    const call = (code: string) =>
+      client.callTool({
+        name: "browser_run",
+        arguments: { code, cdpUrl: browser.cdpUrl },
+      });
+    const result = await call(`
       await browse.open("data:text/html,<title>Runtime</title><h1>Hello</h1><input id=name><button>Go</button>");
       await browse.fill("#name", "Cloudflare");
       const {tree} = await browse.snapshot();
@@ -92,41 +79,40 @@ test(
       const answer: number = 42;
       return {answer, title: await browse.get("title"), value: await browse.get("value", "#name")};
     `);
-      assert.equal(result.isError, false, JSON.stringify(result));
-      assert.deepEqual((result.structuredContent as { value: unknown }).value, {
-        answer: 42,
-        title: { title: "Runtime" },
-        value: { value: "Cloudflare" },
-      });
-      const loop = await call("while (true) {}");
-      assert.equal(loop.isError, true);
-      assert.equal(
-        (loop.structuredContent as { error: { name: string } }).error.name,
-        "RunTimeoutError",
-      );
-      const screenshot = await fetch(`${base}/screen`, {
-        method: "POST",
-        body: JSON.stringify(browser),
-      });
-      assert.equal(screenshot.status, 200);
-      assert.equal(screenshot.headers.get("content-type"), "image/jpeg");
-      assert.ok((await screenshot.arrayBuffer()).byteLength > 100);
-      const shutdown = await fetch(`${base}/browser`, {
-        method: "DELETE",
-        body: JSON.stringify(browser),
-      });
-      assert.equal(shutdown.status, 204);
-    } finally {
-      await client.close().catch(() => {});
-      if (child.pid && child.exitCode === null) {
-        if (process.platform === "win32") child.kill("SIGTERM");
-        else process.kill(-child.pid, "SIGTERM");
-        await exit;
-      }
-      const borrowedSurvived = await cdpReady(chromePort);
-      await local.shutdown();
-      assert.equal(borrowedSurvived, true);
-      assert.equal(await cdpReady(chromePort), false);
+    assert.equal(result.isError, false, JSON.stringify(result));
+    assert.deepEqual((result.structuredContent as { value: unknown }).value, {
+      answer: 42,
+      title: { title: "Runtime" },
+      value: { value: "Cloudflare" },
+    });
+    const loop = await call("while (true) {}");
+    assert.equal(loop.isError, true);
+    assert.equal(
+      (loop.structuredContent as { error: { name: string } }).error.name,
+      "RunTimeoutError",
+    );
+    const screenshot = await fetch(`${base}/screen`, {
+      method: "POST",
+      body: JSON.stringify(browser),
+    });
+    assert.equal(screenshot.status, 200);
+    assert.equal(screenshot.headers.get("content-type"), "image/jpeg");
+    assert.ok((await screenshot.arrayBuffer()).byteLength > 100);
+    const shutdown = await fetch(`${base}/browser`, {
+      method: "DELETE",
+      body: JSON.stringify(browser),
+    });
+    assert.equal(shutdown.status, 204);
+  } finally {
+    await client.close().catch(() => {});
+    if (child.pid && child.exitCode === null) {
+      if (process.platform === "win32") child.kill("SIGTERM");
+      else process.kill(-child.pid, "SIGTERM");
+      await exit;
     }
-  },
-);
+    const borrowedSurvived = await cdpReady(chromePort);
+    await local.shutdown();
+    assert.equal(borrowedSurvived, true);
+    assert.equal(await cdpReady(chromePort), false);
+  }
+});
diff --git a/packages/mcp-server/tests/sandbox.test.ts b/packages/mcp-server/tests/sandbox.test.ts
index e1c3684..8660680 100644
--- a/packages/mcp-server/tests/sandbox.test.ts
+++ b/packages/mcp-server/tests/sandbox.test.ts
@@ -5,21 +5,28 @@ import { runProgram } from "../src/sandbox/runner.ts";
 import { createFakeBrowser, echoHandler } from "./helpers/fake-browser.ts";
 
 test("TypeScript is stripped inside the sandbox boundary", async () => {
-  const result = await runProgram({ code: "const value: number = 42; return value;", session: createFakeBrowser() });
+  const result = await runProgram({
+    code: "const value: number = 42; return value;",
+    session: createFakeBrowser(),
+  });
   assert.equal(result.value, 42);
 });
 
 test("a timeout disposes pending host promises without crashing the runtime", async () => {
   const result = await runProgram({
     code: 'return await browse.get("url");',
-    session: createFakeBrowser(() => new Promise(() => {})), limits: { timeoutMs: 30 },
+    session: createFakeBrowser(() => new Promise(() => {})),
+    limits: { timeoutMs: 30 },
   });
   assert.equal(result.status, "failed");
   assert.equal(result.error?.name, "RunTimeoutError");
 });
 
 test("host prototype members are not sandbox capabilities", async () => {
-  const result = await runProgram({ code: 'return await __host("constructor", "constructor", "[]");', session: createFakeBrowser() });
+  const result = await runProgram({
+    code: 'return await __host("constructor", "constructor", "[]");',
+    session: createFakeBrowser(),
+  });
   assert.equal(result.status, "failed");
   assert.match(result.error?.message ?? "", /Unknown host function/);
 });
diff --git a/packages/mcp-server/tsconfig.json b/packages/mcp-server/tsconfig.json
index e8241d2..486440a 100644
--- a/packages/mcp-server/tsconfig.json
+++ b/packages/mcp-server/tsconfig.json
@@ -1,14 +1,10 @@
 {
   "compilerOptions": {
     "target": "ES2023",
-    "lib": [
-      "ES2023", "DOM"
-    ],
+    "lib": ["ES2023", "DOM"],
     "module": "NodeNext",
     "moduleResolution": "nodenext",
-    "types": [
-      "node"
-    ],
+    "types": ["node"],
     "outDir": "dist",
     "rootDir": "src",
     "strict": true,
@@ -25,7 +21,5 @@
     "isolatedModules": true,
     "rewriteRelativeImportExtensions": true
   },
-  "include": [
-    "src/**/*.ts"
-  ]
+  "include": ["src/**/*.ts"]
 }
diff --git a/packages/tools/package.json b/packages/tools/package.json
index 94e175e..399cc8c 100644
--- a/packages/tools/package.json
+++ b/packages/tools/package.json
@@ -26,8 +26,12 @@
     "ai": "^7.0.0"
   },
   "peerDependenciesMeta": {
-    "@mastra/core": { "optional": true },
-    "ai": { "optional": true }
+    "@mastra/core": {
+      "optional": true
+    },
+    "ai": {
+      "optional": true
+    }
   },
   "devDependencies": {
     "@mastra/core": "1.67.0",
diff --git a/packages/tools/src/ai-sdk.ts b/packages/tools/src/ai-sdk.ts
index bc7af9f..526680a 100644
--- a/packages/tools/src/ai-sdk.ts
+++ b/packages/tools/src/ai-sdk.ts
@@ -15,24 +15,28 @@
 import { tool } from "ai";
 
 import {
-  createBrowserToolkit,
-  liveViewModelOutput,
-  toModelOutput,
   type Browser,
   type BrowserToolkit,
   type BrowserToolsOptions,
+  createBrowserToolkit,
+  liveViewModelOutput,
   type SessionToolkit,
+  toModelOutput,
 } from "./index.ts";
 
-export { instructions, type BrowserToolsOptions, type BrowserRunOutput } from "./index.ts";
+export { type BrowserRunOutput, type BrowserToolsOptions, instructions } from "./index.ts";
 
 type RunTools = ReturnType<typeof runTools>;
 type SessionTools = ReturnType<typeof sessionTools>;
 
 /** With a `browser`, the session tools join `browser_api` and `browser_run`. */
-export function browserTools(options: BrowserToolsOptions & { browser: Browser }): RunTools & SessionTools;
+export function browserTools(
+  options: BrowserToolsOptions & { browser: Browser },
+): RunTools & SessionTools;
 export function browserTools(options?: BrowserToolsOptions): RunTools;
-export function browserTools(options: BrowserToolsOptions = {}): RunTools | (RunTools & SessionTools) {
+export function browserTools(
+  options: BrowserToolsOptions = {},
+): RunTools | (RunTools & SessionTools) {
   const toolkit = createBrowserToolkit(options);
   const tools = runTools(toolkit);
   return toolkit.sessions ? { ...tools, ...sessionTools(toolkit.sessions) } : tools;
diff --git a/packages/tools/src/browser.ts b/packages/tools/src/browser.ts
index 9b8f7c2..58b9918 100644
--- a/packages/tools/src/browser.ts
+++ b/packages/tools/src/browser.ts
@@ -23,8 +23,8 @@
  */
 
 import {
-  captureScreenshot,
   type BrowserProvider,
+  captureScreenshot,
   type ToolDeps,
 } from "@browse-code-mode/mcp-server/core";
 
diff --git a/packages/tools/src/index.ts b/packages/tools/src/index.ts
index e7fd1a0..96899ad 100644
--- a/packages/tools/src/index.ts
+++ b/packages/tools/src/index.ts
@@ -7,36 +7,36 @@
  * `./ai-sdk` and `./mastra` wrap this toolkit in each framework's tool type.
  */
 
-import { z } from "zod";
 import {
   API_TOOL_DESCRIPTION,
-  INSTRUCTIONS,
+  type BrowserProvider,
   executeBrowserRun,
+  INSTRUCTIONS,
   loadConfig,
   providerFromEnv,
   renderBrowserApi,
   runInputShape,
   runToolDescription,
   staticProvider,
-  type BrowserProvider,
   type ToolDeps,
 } from "@browse-code-mode/mcp-server/core";
+import { z } from "zod";
 
 import type { Browser, BrowserSession, LiveView } from "./browser.ts";
 
 export {
+  type BrowserHandle,
+  type BrowserProvider,
   browserProvider,
   providerFromEnv,
   staticProvider,
-  type BrowserHandle,
-  type BrowserProvider,
 } from "@browse-code-mode/mcp-server/core";
 export {
-  providerBrowser,
   type Browser,
   type BrowserSession,
   type LiveView,
   type ProviderBrowser,
+  providerBrowser,
 } from "./browser.ts";
 
 export interface BrowserToolsOptions {
@@ -115,7 +115,10 @@ export function createBrowserToolkit(options: BrowserToolsOptions = {}) {
     : undefined;
 
   const sessionIdInput = z.object({
-    sessionId: z.string().min(1).describe("A session id from `browser_start` or `browser_list_sessions`."),
+    sessionId: z
+      .string()
+      .min(1)
+      .describe("A session id from `browser_start` or `browser_list_sessions`."),
   });
   const runShape = runInputShape(config);
   const runInputSchema = browser
@@ -168,7 +171,12 @@ export function createBrowserToolkit(options: BrowserToolsOptions = {}) {
           const session = sessionId ? sessions.find((s) => s.id === sessionId) : sessions.at(-1);
           if (sessionId && !session) {
             const text = `Unknown browser session: ${sessionId}. Call browser_list_sessions for the open ones.`;
-            return { text, isError: true, status: "failed", error: { name: "Error", message: text } };
+            return {
+              text,
+              isError: true,
+              status: "failed",
+              error: { name: "Error", message: text },
+            };
           }
           if (session) input.cdpUrl = session.cdpUrl;
           label = session ? `session ${session.id}` : "temporary session";
@@ -216,8 +224,10 @@ export function createBrowserToolkit(options: BrowserToolsOptions = {}) {
               "See a browser session as it is now: a screenshot of the current page, " +
               "plus a URL a person can open to watch it live when the provider has one.",
             inputSchema: sessionIdInput,
-            execute: ({ sessionId }: { sessionId: string }, signal?: AbortSignal): Promise<LiveView> =>
-              browser.liveView(sessionId, signal ? { signal } : {}),
+            execute: (
+              { sessionId }: { sessionId: string },
+              signal?: AbortSignal,
+            ): Promise<LiveView> => browser.liveView(sessionId, signal ? { signal } : {}),
           },
         }
       : undefined,
@@ -255,8 +265,17 @@ export function liveViewModelOutput({ url, screenshot }: LiveView) {
   return {
     type: "content" as const,
     value: [
-      { type: "text" as const, text: url ? `Live view: ${url}` : "No live view URL for this session; screenshot of the current page:" },
-      { type: "file" as const, mediaType: screenshot.mediaType, data: { type: "data" as const, data: screenshot.base64 } },
+      {
+        type: "text" as const,
+        text: url
+          ? `Live view: ${url}`
+          : "No live view URL for this session; screenshot of the current page:",
+      },
+      {
+        type: "file" as const,
+        mediaType: screenshot.mediaType,
+        data: { type: "data" as const, data: screenshot.base64 },
+      },
     ],
   };
 }
diff --git a/packages/tools/src/mastra.ts b/packages/tools/src/mastra.ts
index 3c89339..7d267e6 100644
--- a/packages/tools/src/mastra.ts
+++ b/packages/tools/src/mastra.ts
@@ -14,26 +14,30 @@
 import { createTool } from "@mastra/core/tools";
 
 import {
-  createBrowserToolkit,
-  liveViewModelOutput,
-  toModelOutput,
-  type BrowserRunOutput,
-  type LiveView,
   type Browser,
+  type BrowserRunOutput,
   type BrowserToolkit,
   type BrowserToolsOptions,
+  createBrowserToolkit,
+  type LiveView,
+  liveViewModelOutput,
   type SessionToolkit,
+  toModelOutput,
 } from "./index.ts";
 
-export { instructions, type BrowserToolsOptions, type BrowserRunOutput } from "./index.ts";
+export { type BrowserRunOutput, type BrowserToolsOptions, instructions } from "./index.ts";
 
 type RunTools = ReturnType<typeof runTools>;
 type SessionTools = ReturnType<typeof sessionTools>;
 
 /** With a `browser`, the session tools join `browser_api` and `browser_run`. */
-export function browserTools(options: BrowserToolsOptions & { browser: Browser }): RunTools & SessionTools;
+export function browserTools(
+  options: BrowserToolsOptions & { browser: Browser },
+): RunTools & SessionTools;
 export function browserTools(options?: BrowserToolsOptions): RunTools;
-export function browserTools(options: BrowserToolsOptions = {}): RunTools | (RunTools & SessionTools) {
+export function browserTools(
+  options: BrowserToolsOptions = {},
+): RunTools | (RunTools & SessionTools) {
   const toolkit = createBrowserToolkit(options);
   const tools = runTools(toolkit);
   return toolkit.sessions ? { ...tools, ...sessionTools(toolkit.sessions) } : tools;
diff --git a/packages/tools/tests/browser.test.ts b/packages/tools/tests/browser.test.ts
index 32d2f39..0d3f1f1 100644
--- a/packages/tools/tests/browser.test.ts
+++ b/packages/tools/tests/browser.test.ts
@@ -25,7 +25,10 @@ test("hosted sessions are created on start and released once on close", async (t
     requests.push(`${init.method} ${url}`);
     if (!url.endsWith("/sessions")) return Response.json({});
     created += 1;
-    return Response.json({ id: `session-${created}`, connectUrl: `wss://browserbase/session-${created}` });
+    return Response.json({
+      id: `session-${created}`,
+      connectUrl: `wss://browserbase/session-${created}`,
+    });
   });
 
   const browser = providerBrowser(
@@ -52,7 +55,12 @@ test("live view returns a screenshot, plus the provider's URL when it has one",
     {
       name: "test",
       async create() {
-        return { provider: "test", cdpUrl: "ws://watched", sessionId: "s1", liveViewUrl: "https://live/s1" };
+        return {
+          provider: "test",
+          cdpUrl: "ws://watched",
+          sessionId: "s1",
+          liveViewUrl: "https://live/s1",
+        };
       },
       async shutdown() {},
     },
diff --git a/packages/tools/tests/tools.test.ts b/packages/tools/tests/tools.test.ts
index 97dd7e9..f733687 100644
--- a/packages/tools/tests/tools.test.ts
+++ b/packages/tools/tests/tools.test.ts
@@ -5,14 +5,14 @@ import { generateText, stepCountIs } from "ai";
 import { MockLanguageModelV4 } from "ai/test";
 
 import { browserTools as aiSdkTools } from "../src/ai-sdk.ts";
-import { browserTools as mastraTools } from "../src/mastra.ts";
 import {
-  providerBrowser,
   type BrowserRunOutput,
   type BrowserToolsOptions,
   type LiveView,
+  providerBrowser,
   type SessionSummary,
 } from "../src/index.ts";
+import { browserTools as mastraTools } from "../src/mastra.ts";
 
 /** Answers commands like a page titled "Fake"; no Chrome needed. */
 function fakeBrowser() {
@@ -46,14 +46,16 @@ test("AI SDK: the model runs a program and reads the compact result text", async
       prompts.push(prompt);
       if (prompts.length === 1) {
         return {
-          content: [{
-            type: "tool-call",
-            toolCallId: "call-1",
-            toolName: "browser_run",
-            input: JSON.stringify({
-              code: `await browse.open("https://example.com"); return (await browse.get("title")).title;`,
-            }),
-          }],
+          content: [
+            {
+              type: "tool-call",
+              toolCallId: "call-1",
+              toolName: "browser_run",
+              input: JSON.stringify({
+                code: `await browse.open("https://example.com"); return (await browse.get("title")).title;`,
+              }),
+            },
+          ],
           finishReason: { unified: "tool-calls", raw: undefined },
           usage,
           warnings: [],
@@ -98,7 +100,11 @@ test("AI SDK: a failed program is reported to the model as an error", async () =
   )) as BrowserRunOutput;
   assert.equal(output.isError, true);
   assert.match(output.text, /unexpected command back/);
-  const modelOutput = await tools.browser_run.toModelOutput!({ toolCallId: "1", input: { code: "" }, output });
+  const modelOutput = await tools.browser_run.toModelOutput!({
+    toolCallId: "1",
+    input: { code: "" },
+    output,
+  });
   assert.equal(modelOutput.type, "error-text");
 });
 
@@ -107,7 +113,10 @@ test("Mastra: tools share ids, descriptions, and execution", async () => {
   const tools = mastraTools({ cdpUrl: "ws://fake", connect, env: {} });
   assert.equal(tools.browser_run.id, "browser_run");
   assert.match(tools.browser_run.description, /Evaluate a TypeScript program/);
-  assert.match(await tools.browser_api.execute!({}, {} as never) as string, /declare const browse/);
+  assert.match(
+    (await tools.browser_api.execute!({}, {} as never)) as string,
+    /declare const browse/,
+  );
 
   const output = (await tools.browser_run.execute!(
     { code: `return (await browse.get("title")).title;` },
@@ -134,7 +143,10 @@ test("without cdpUrl, each program leases and releases a provider browser", asyn
       },
     },
   });
-  await tools.browser_run.execute!({ code: `return 1;` }, { toolCallId: "1", messages: [], context: {} });
+  await tools.browser_run.execute!(
+    { code: `return 1;` },
+    { toolCallId: "1", messages: [], context: {} },
+  );
   assert.deepEqual(lifecycle, ["create", "shutdown"]);
   assert.deepEqual(state.endpoints, ["ws://leased"]);
 });
@@ -172,7 +184,10 @@ test("with a Browser, the model starts a session, drives it by id, watches it, a
   assert.deepEqual(Object.keys(started).sort(), ["id", "provider", "startedAt"]);
   await tools.browser_start!.execute!({}, options);
 
-  const first = (await tools.browser_run.execute!({ code: `return 1;`, sessionId: "s1" }, options)) as BrowserRunOutput;
+  const first = (await tools.browser_run.execute!(
+    { code: `return 1;`, sessionId: "s1" },
+    options,
+  )) as BrowserRunOutput;
   await tools.browser_run.execute!({ code: `return 1;` }, options);
   assert.match(first.text, /· session s1\n/);
   assert.doesNotMatch(JSON.stringify(first), /ws:\/\//);
@@ -186,13 +201,22 @@ test("with a Browser, the model starts a session, drives it by id, watches it, a
   assert.match(unknown.text, /Unknown browser session: nope/);
 
   const view = (await tools.browser_live_view!.execute!({ sessionId: "s1" }, options)) as LiveView;
-  const viewOutput = await tools.browser_live_view!.toModelOutput!({ toolCallId: "1", input: { sessionId: "s1" }, output: view });
+  const viewOutput = await tools.browser_live_view!.toModelOutput!({
+    toolCallId: "1",
+    input: { sessionId: "s1" },
+    output: view,
+  });
   assert.equal(viewOutput.type, "content");
   assert.match(JSON.stringify(viewOutput), /"mediaType":"image\/jpeg".*"SlBFRw=="/);
 
   await tools.browser_stop!.execute!({ sessionId: "s1" }, options);
-  const { sessions } = (await tools.browser_list_sessions!.execute!({}, options)) as { sessions: SessionSummary[] };
-  assert.deepEqual(sessions.map((s) => s.id), ["s2"]);
+  const { sessions } = (await tools.browser_list_sessions!.execute!({}, options)) as {
+    sessions: SessionSummary[];
+  };
+  assert.deepEqual(
+    sessions.map((s) => s.id),
+    ["s2"],
+  );
   assert.deepEqual(shutdowns, ["s1"]);
 });
 
@@ -219,5 +243,8 @@ test("with a Browser and no open session, browser_run uses a temporary one", asy
 test("without a Browser there are no session tools", () => {
   const tools = aiSdkTools({ cdpUrl: "ws://fake", env: {} });
   assert.deepEqual(Object.keys(tools).sort(), ["browser_api", "browser_run"]);
-  assert.throws(() => aiSdkTools({ cdpUrl: "ws://fake", browser: providerBrowser({} as never) }), /not both/);
+  assert.throws(
+    () => aiSdkTools({ cdpUrl: "ws://fake", browser: providerBrowser({} as never) }),
+    /not both/,
+  );
 });
diff --git a/packages/tools/tsconfig.json b/packages/tools/tsconfig.json
index 31f4bb8..3a11ed5 100644
--- a/packages/tools/tsconfig.json
+++ b/packages/tools/tsconfig.json
@@ -1,14 +1,10 @@
 {
   "compilerOptions": {
     "target": "ES2023",
-    "lib": [
-      "ES2023", "DOM"
-    ],
+    "lib": ["ES2023", "DOM"],
     "module": "NodeNext",
     "moduleResolution": "nodenext",
-    "types": [
-      "node"
-    ],
+    "types": ["node"],
     "rootDir": ".",
     "strict": true,
     "exactOptionalPropertyTypes": true,
@@ -23,7 +19,5 @@
     "isolatedModules": true,
     "rewriteRelativeImportExtensions": true
   },
-  "include": [
-    "src/**/*.ts", "tests/**/*.ts", "../mcp-server/src/**/*.d.ts"
-  ]
+  "include": ["src/**/*.ts", "tests/**/*.ts", "../mcp-server/src/**/*.d.ts"]
 }
diff --git a/scripts/chrome.mjs b/scripts/chrome.mjs
index 3ffcad6..4175c6d 100755
--- a/scripts/chrome.mjs
+++ b/scripts/chrome.mjs
@@ -16,9 +16,7 @@ process.on("SIGINT", () => void stop());
 process.on("SIGTERM", () => void stop());
 try {
   const browser = await starting;
-  console.log(
-    `CDP browser on ${browser.browser.cdpUrl} (${browser.owned ? "owned" : "borrowed"})`,
-  );
+  console.log(`CDP browser on ${browser.browser.cdpUrl} (${browser.owned ? "owned" : "borrowed"})`);
   if (!browser.owned) process.exit(0);
   browser.process?.once("exit", async () => {
     await browser.shutdown();
diff --git a/scripts/dev.mjs b/scripts/dev.mjs
index de414f2..ef7ce2e 100755
--- a/scripts/dev.mjs
+++ b/scripts/dev.mjs
@@ -129,12 +129,10 @@ async function shutdown(code = 0) {
   startup.abort();
   await Promise.all(
     children.map(async ({ child }) => {
-      if (!child.pid || child.exitCode !== null || child.signalCode !== null)
-        return;
+      if (!child.pid || child.exitCode !== null || child.signalCode !== null) return;
       const kill = (signal) => {
         try {
-          if (process.platform !== "win32" && child.pid)
-            process.kill(-child.pid, signal);
+          if (process.platform !== "win32" && child.pid) process.kill(-child.pid, signal);
           else child.kill(signal);
         } catch {}
       };
@@ -145,8 +143,7 @@ async function shutdown(code = 0) {
       clearTimeout(timer);
     }),
   );
-  const browser =
-    localBrowser ?? (await startingBrowser?.catch(() => undefined));
+  const browser = localBrowser ?? (await startingBrowser?.catch(() => undefined));
   await browser?.shutdown();
   process.exit(code);
 }
@@ -157,9 +154,7 @@ process.on("SIGTERM", () => shutdown(0));
 // ------------------------------------------------------------- 0. preflight
 // A stale server on either port would let this script report success while the
 // UI talked to yesterday's code, so refuse to start rather than guess.
-for (const [label, port] of [
-  ["web app", WEB_PORT],
-]) {
+for (const [label, port] of [["web app", WEB_PORT]]) {
   if (await portInUse(port)) {
     log("dev", `Port ${port} is already in use, so the ${label} cannot start.`);
     log(
@@ -182,10 +177,7 @@ try {
     await localBrowser.shutdown();
     process.exit(0);
   }
-  log(
-    "chrome",
-    `${localBrowser.owned ? "started" : "borrowed"} browser on :${CHROME_PORT}`,
-  );
+  log("chrome", `${localBrowser.owned ? "started" : "borrowed"} browser on :${CHROME_PORT}`);
   localBrowser.process?.once("exit", () => {
     void shutdown(1);
   });
@@ -197,26 +189,16 @@ try {
 {
   // ----------------------------------------------------------------- 3. web app
   if (!process.env.ANTHROPIC_API_KEY) {
-    log(
-      "web",
-      "ANTHROPIC_API_KEY is not set — the UI will load but chat will fail.",
-    );
+    log("web", "ANTHROPIC_API_KEY is not set — the UI will load but chat will fail.");
   }
-  run(
-    "web",
-    "pnpm",
-    ["--filter", "@browse-code-mode/web", "dev", "--port", String(WEB_PORT)],
-    {
-      env: {
-    BROWSE_PROVIDER: "cdp",
-    PORT: String(WEB_PORT),
-        BROWSE_CDP_URL: String(CHROME_PORT),
-      },
+  run("web", "pnpm", ["--filter", "@browse-code-mode/web", "dev", "--port", String(WEB_PORT)], {
+    env: {
+      BROWSE_PROVIDER: "cdp",
+      PORT: String(WEB_PORT),
+      BROWSE_CDP_URL: String(CHROME_PORT),
     },
-  );
-  if (
-    !(await waitForHttp(`http://localhost:${WEB_PORT}/`, 60_000, "web app"))
-  ) {
+  });
+  if (!(await waitForHttp(`http://localhost:${WEB_PORT}/`, 60_000, "web app"))) {
     shutdown(1);
   }
 
@@ -225,11 +207,7 @@ try {
   log("dev", `ready — ${url}`);
   if (process.env.NO_OPEN !== "1") {
     const opener =
-      process.platform === "darwin"
-        ? "open"
-        : process.platform === "win32"
-          ? "start"
-          : "xdg-open";
+      process.platform === "darwin" ? "open" : process.platform === "win32" ? "start" : "xdg-open";
     spawn(opener, [url], { stdio: "ignore", detached: true }).unref();
   }
 }

From 6037cdc464b94c70aa6cfc635d8212c0514bbd35 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 24 Sep 2026 15:01:39 +0000
Subject: [PATCH 3/6] Fix Biome lint diagnostics

Replace non-null assertions with explicit narrowing, type the CDP
accessibility and frame-tree payloads that snapshots read, and route
remaining untyped CDP JSON through one documented CdpPayload alias.
Add a button type, and split message part rendering so the index key
lives in one place.

Co-authored-by: Anirudh Kamath <kamath@users.noreply.github.com>
---
 apps/web/src/routes/api.chat.ts               |  4 +-
 apps/web/src/routes/index.tsx                 | 56 +++++++------
 examples/02-mcp-server/index.ts               |  9 ++-
 packages/mcp-server/src/app.ts                |  9 +--
 packages/mcp-server/src/browse/driver.ts      | 18 ++---
 .../mcp-server/src/browse/host-functions.ts   |  5 +-
 packages/mcp-server/src/browse/page.ts        | 78 ++++++++++++-------
 packages/mcp-server/src/browse/selectors.ts   |  3 +-
 packages/mcp-server/src/browse/transport.ts   | 15 +++-
 packages/mcp-server/tests/frames.e2e.test.ts  |  3 +-
 packages/mcp-server/tests/lifecycle.test.ts   |  6 +-
 packages/mcp-server/tests/mcp.test.ts         |  4 +-
 packages/tools/src/index.ts                   |  7 +-
 packages/tools/tests/tools.test.ts            | 59 ++++++++------
 14 files changed, 168 insertions(+), 108 deletions(-)

diff --git a/apps/web/src/routes/api.chat.ts b/apps/web/src/routes/api.chat.ts
index 150f084..3253095 100644
--- a/apps/web/src/routes/api.chat.ts
+++ b/apps/web/src/routes/api.chat.ts
@@ -3,7 +3,7 @@ import { createFileRoute } from "@tanstack/react-router";
 import { convertToModelMessages, stepCountIs, streamText, type UIMessage } from "ai";
 
 import { env } from "../lib/env.ts";
-import { openMcpSession } from "../lib/mcp.ts";
+import { type McpSession, openMcpSession } from "../lib/mcp.ts";
 
 const SYSTEM = `You drive a real web browser by writing TypeScript programs and running them with the browser_run tool.
 
@@ -37,7 +37,7 @@ export const Route = createFileRoute("/api/chat")({
         if (!cdpUrl || typeof cdpUrl !== "string")
           return Response.json({ error: "Start a browser first." }, { status: 400 });
 
-        let session;
+        let session: McpSession;
         try {
           session = await openMcpSession(cdpUrl);
         } catch (error) {
diff --git a/apps/web/src/routes/index.tsx b/apps/web/src/routes/index.tsx
index 6274f5b..3abb655 100644
--- a/apps/web/src/routes/index.tsx
+++ b/apps/web/src/routes/index.tsx
@@ -60,7 +60,7 @@ function Home() {
     <div className="split">
       <div className="viewport" style={{ display: "flex", flexDirection: "column" }}>
         <div style={{ padding: 12 }}>
-          <button onClick={() => void lifecycle()} disabled={busy}>
+          <button type="button" onClick={() => void lifecycle()} disabled={busy}>
             {busy ? "Working…" : browser ? "Stop browser" : "Start browser"}
           </button>
           {browser ? (
@@ -187,6 +187,7 @@ function Chat({ cdpUrl }: { cdpUrl: string }) {
 
   // Scroll the list itself. `scrollIntoView` walks up the ancestor chain and
   // will scroll the document too, which drags the whole two-pane layout.
+  // biome-ignore lint/correctness/useExhaustiveDependencies: the dependencies are the triggers; the effect reads only the ref.
   useEffect(() => {
     const list = listRef.current;
     if (list) list.scrollTop = list.scrollHeight;
@@ -233,32 +234,41 @@ function Chat({ cdpUrl }: { cdpUrl: string }) {
 function Message({ message }: { message: UIMessage }) {
   return (
     <div className={`msg msg-${message.role}`}>
-      {message.parts.map((part, index) => {
-        if (part.type === "text") {
-          if (!part.text.trim()) return null;
-          // Assistant replies use tables and lists, so they render as markdown;
-          // a user's own words are shown verbatim rather than reinterpreted as
-          // markup. Streamdown rather than react-markdown because it renders
-          // markdown that is still arriving, so a half-written table or fence
-          // does not flash as raw text mid-stream.
-          return message.role === "assistant" ? (
-            <div key={index} className="bubble markdown">
-              <Streamdown>{part.text}</Streamdown>
-            </div>
-          ) : (
-            <div key={index} className="bubble">
-              {part.text}
-            </div>
-          );
-        }
-
-        const call = asToolCall(part);
-        return call ? <ToolCall key={index} call={call} /> : null;
-      })}
+      {message.parts.map((part, index) => (
+        // biome-ignore lint/suspicious/noArrayIndexKey: parts only append and text parts have no id, so the index is stable.
+        <MessagePart key={index} role={message.role} part={part} />
+      ))}
     </div>
   );
 }
 
+function MessagePart({
+  role,
+  part,
+}: {
+  role: UIMessage["role"];
+  part: UIMessage["parts"][number];
+}) {
+  if (part.type === "text") {
+    if (!part.text.trim()) return null;
+    // Assistant replies use tables and lists, so they render as markdown;
+    // a user's own words are shown verbatim rather than reinterpreted as
+    // markup. Streamdown rather than react-markdown because it renders
+    // markdown that is still arriving, so a half-written table or fence
+    // does not flash as raw text mid-stream.
+    return role === "assistant" ? (
+      <div className="bubble markdown">
+        <Streamdown>{part.text}</Streamdown>
+      </div>
+    ) : (
+      <div className="bubble">{part.text}</div>
+    );
+  }
+
+  const call = asToolCall(part);
+  return call ? <ToolCall call={call} /> : null;
+}
+
 interface ToolCallView {
   name: string;
   state: string;
diff --git a/examples/02-mcp-server/index.ts b/examples/02-mcp-server/index.ts
index 3a0541c..7d40401 100644
--- a/examples/02-mcp-server/index.ts
+++ b/examples/02-mcp-server/index.ts
@@ -11,7 +11,11 @@
 
 import { createServer } from "node:http";
 import { localProvider } from "@browse-code-mode/mcp-server/local-browser";
-import { createBrowserToolkit, providerBrowser } from "@browse-code-mode/tools";
+import {
+  createBrowserToolkit,
+  providerBrowser,
+  type SessionToolkit,
+} from "@browse-code-mode/tools";
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
 
@@ -22,7 +26,8 @@ const host = "127.0.0.1";
 // Sessions outlive each stateless request because they live in this process.
 const browser = providerBrowser(localProvider());
 const toolkit = createBrowserToolkit({ browser });
-const sessions = toolkit.sessions!;
+if (!toolkit.sessions) throw new Error("A toolkit created with a browser has session tools.");
+const sessions: SessionToolkit = toolkit.sessions;
 
 const json = (value: unknown) => ({
   content: [{ type: "text" as const, text: JSON.stringify(value, null, 2) }],
diff --git a/packages/mcp-server/src/app.ts b/packages/mcp-server/src/app.ts
index c694211..128aed4 100644
--- a/packages/mcp-server/src/app.ts
+++ b/packages/mcp-server/src/app.ts
@@ -187,15 +187,12 @@ export function createApp({
       );
     }
 
+    const cdpUrl = c.req.header("x-browse-cdp-url");
     const server = createMcpServer({
-      config: c.req.header("x-browse-cdp-url")
-        ? { ...config, defaultCdpUrl: c.req.header("x-browse-cdp-url")! }
-        : config,
+      config: cdpUrl ? { ...config, defaultCdpUrl: cdpUrl } : config,
       ...(run ? { run } : {}),
       ...(connect ? { connect } : {}),
-      provider: c.req.header("x-browse-cdp-url")
-        ? staticProvider(c.req.header("x-browse-cdp-url"))
-        : provider,
+      provider: cdpUrl ? staticProvider(cdpUrl) : provider,
     });
     // No `sessionIdGenerator`: the transport runs in stateless mode.
     const transport = new WebStandardStreamableHTTPServerTransport();
diff --git a/packages/mcp-server/src/browse/driver.ts b/packages/mcp-server/src/browse/driver.ts
index 17ca2c7..ee2f674 100644
--- a/packages/mcp-server/src/browse/driver.ts
+++ b/packages/mcp-server/src/browse/driver.ts
@@ -511,8 +511,9 @@ const HANDLERS: Record<string, Handler> = {
             0,
             pages.findIndex((p) => p.pageId === active?.pageId),
           ),
-          page: active ?? pages[0]!,
+          page: active ?? pages[0],
         };
+    if (!resolved.page) throw new BrowseCommandError("No tab is open.");
 
     const closedTargetId = resolved.page.pageId;
     await resolved.page.close();
@@ -563,10 +564,11 @@ async function resolveTab(
   }
 
   const index = pages.findIndex((page) => page.pageId === tab);
-  if (index === -1) {
+  const page = pages[index];
+  if (!page) {
     throw new BrowseCommandError(`Tab "${tab}" was not found. Call tab.list() for current tabs.`);
   }
-  return { index, page: pages[index]! };
+  return { index, page };
 }
 
 async function safeTitle(page: Page): Promise<string> {
@@ -632,17 +634,15 @@ export function formatTree(
   if (filter) {
     const match = matcher(filter);
     const keep = new Set<number>();
-    const ancestors: number[] = [];
+    const ancestors: Array<{ index: number; depth: number }> = [];
     lines.forEach((line, index) => {
       const depth = indentWidth(line);
-      while (ancestors.length > 0 && indentWidth(lines[ancestors.at(-1)!]!) >= depth) {
-        ancestors.pop();
-      }
+      while ((ancestors.at(-1)?.depth ?? -1) >= depth) ancestors.pop();
       if (match(line)) {
         keep.add(index);
-        for (const ancestor of ancestors) keep.add(ancestor);
+        for (const ancestor of ancestors) keep.add(ancestor.index);
       }
-      ancestors.push(index);
+      ancestors.push({ index, depth });
     });
     lines = lines.filter((_, index) => keep.has(index));
   }
diff --git a/packages/mcp-server/src/browse/host-functions.ts b/packages/mcp-server/src/browse/host-functions.ts
index 54f2faf..93b0fbf 100644
--- a/packages/mcp-server/src/browse/host-functions.ts
+++ b/packages/mcp-server/src/browse/host-functions.ts
@@ -71,8 +71,9 @@ export function createHostFunctions(options: HostFunctionOptions): HostFunctionB
     const key = `${spec.group}.${spec.fn}`;
     if (!isPermitted(key, options)) continue;
     exposed.push(key);
-    hostFunctions[spec.group]![spec.fn] = (...args: unknown[]) =>
-      invoke(spec, args, calls, counter, options);
+    const group = hostFunctions[spec.group] ?? {};
+    hostFunctions[spec.group] = group;
+    group[spec.fn] = (...args: unknown[]) => invoke(spec, args, calls, counter, options);
   }
 
   return { hostFunctions, calls, exposed };
diff --git a/packages/mcp-server/src/browse/page.ts b/packages/mcp-server/src/browse/page.ts
index 9aa601b..3724ff5 100644
--- a/packages/mcp-server/src/browse/page.ts
+++ b/packages/mcp-server/src/browse/page.ts
@@ -2,7 +2,7 @@
 
 import { resolveCdpUrl } from "./cdp.ts";
 import type { FrameTarget, ResolvedSelector } from "./selectors.ts";
-import { CdpConnection, type OpenSocket, openWebSocket } from "./transport.ts";
+import { CdpConnection, type CdpPayload, type OpenSocket, openWebSocket } from "./transport.ts";
 
 export type LoadState = "load" | "domcontentloaded" | "networkidle";
 export type MouseButton = "left" | "middle" | "right";
@@ -102,7 +102,7 @@ export class Page {
         if (params.targetInfo?.type !== "iframe") return;
         this.oopifs.set(params.targetInfo.targetId, {
           sessionId: params.sessionId,
-          parentSessionId: session!,
+          parentSessionId: session,
         });
         // A cross-site frame can hold cross-site frames of its own.
         this.watch(this.autoAttach(params.sessionId));
@@ -114,7 +114,7 @@ export class Page {
         return;
       }
       if (method.startsWith("Runtime.executionContext") && this.ownsSession(session)) {
-        this.trackWorld(session!, method, params);
+        this.trackWorld(session, method, params);
         return;
       }
       if (session !== sessionId) return;
@@ -157,14 +157,17 @@ export class Page {
     const tracked = pending.catch(() => {}).finally(() => this.attaching.delete(tracked));
     this.attaching.add(tracked);
   }
-  private ownsSession(session: string | undefined): boolean {
+  private ownsSession(session: string | undefined): session is string {
     if (session === this.sessionId) return true;
     for (const frame of this.oopifs.values()) if (frame.sessionId === session) return true;
     return false;
   }
-  private trackWorld(session: string, method: string, params: any) {
+  private trackWorld(session: string, method: string, params: CdpPayload) {
     let worlds = this.worlds.get(session);
-    if (!worlds) this.worlds.set(session, (worlds = new Map()));
+    if (!worlds) {
+      worlds = new Map();
+      this.worlds.set(session, worlds);
+    }
     if (method === "Runtime.executionContextsCleared") return worlds.clear();
     if (method === "Runtime.executionContextDestroyed") {
       for (const [frameId, id] of worlds)
@@ -180,7 +183,7 @@ export class Page {
    * only reports context ids after Runtime.enable, so enable it per session on
    * first use; existing contexts arrive before enable returns.
    */
-  async evaluateIn(frame: FrameTarget, expression: string): Promise<any> {
+  async evaluateIn<T = unknown>(frame: FrameTarget, expression: string): Promise<T> {
     let enabling = this.runtimeEnabled.get(frame.sessionId);
     if (!enabling) {
       enabling = this.sendTo(frame.sessionId, "Runtime.enable");
@@ -246,7 +249,7 @@ export class Page {
         }));
         if (!frameTree) return [];
         const found: SnapshotFrame[] = [];
-        const walk = (node: any, root: boolean) => {
+        const walk = (node: FrameTreeNode, root: boolean) => {
           found.push({
             frameId: node.frame.id,
             sessionId,
@@ -279,7 +282,7 @@ export class Page {
     );
     return frames;
   }
-  async evaluate(expression: string): Promise<any> {
+  async evaluate<T = unknown>(expression: string): Promise<T> {
     const response = await this.send("Runtime.evaluate", {
       expression,
       returnByValue: true,
@@ -375,7 +378,7 @@ export class Page {
   }
   async keyPress(combo: string) {
     const parts = combo.split("+");
-    const key = parts.pop()!;
+    const key = parts.pop() ?? "";
     const modifiers = parts.reduce(
       (n, p) => n | ({ Alt: 1, Control: 2, Ctrl: 2, Meta: 4, Shift: 8 }[p] ?? 0),
       0,
@@ -549,8 +552,8 @@ export class Page {
     const renderFrame = (frame: SnapshotFrame, depth: number) => {
       const index = nextFrame++;
       frameMap[index] = { sessionId: frame.sessionId, frameId: frame.frameId };
-      const byId = new Map<string, any>(frame.nodes.map((node: any) => [node.nodeId, node]));
-      const visit = (node: any, depth: number, parentName: string | undefined) => {
+      const byId = new Map(frame.nodes.map((node) => [node.nodeId, node]));
+      const visit = (node: AXNode | undefined, depth: number, parentName: string | undefined) => {
         if (!node) return;
         const role = node.role?.value ?? "node";
         const name = node.name?.value ?? "";
@@ -562,9 +565,8 @@ export class Page {
         if (shown && ref) {
           // Resolve refs using backend node IDs, never a server-side page registry.
           xpathMap[ref] = `backend=${node.backendDOMNodeId}`;
-          const url = node.properties?.find((p: { name: string }) => p.name === "url")?.value
-            ?.value;
-          if (url) urlMap[ref] = url;
+          const url = node.properties?.find((p) => p.name === "url")?.value?.value;
+          if (typeof url === "string" && url) urlMap[ref] = url;
         }
         if (shown)
           lines.push(
@@ -593,9 +595,31 @@ interface SnapshotFrame {
   /** Session holding the <iframe> element; unset for the top frame. */
   ownerSession: string | undefined;
   ownerNode?: number;
-  nodes: any[];
+  nodes: AXNode[];
+}
+
+/** The fields of CDP's `Accessibility.AXNode` that snapshots read. */
+interface AXNode {
+  nodeId: string;
+  parentId?: string;
+  childIds?: string[];
+  backendDOMNodeId?: number;
+  ignored?: boolean;
+  role?: { value?: string };
+  name?: { value?: string };
+  value?: { value?: unknown };
+  properties?: Array<{ name: string; value?: { value?: unknown } }>;
 }
 
+/** CDP's `Page.FrameTree`, trimmed to what `frames()` walks. */
+interface FrameTreeNode {
+  frame: { id: string };
+  childFrames?: FrameTreeNode[];
+}
+
+/** CDP's `DOM.Quad`: four corners as x/y pairs, clockwise. */
+type Quad = [number, number, number, number, number, number, number, number];
+
 /** Where a resolved element lives: its frame's session and a remote object. */
 interface ElementHandle {
   sessionId: string;
@@ -713,9 +737,9 @@ export class Locator {
     });
   }
   /** Run `body` with `el` bound to the element, or to null when nothing matches. */
-  private async apply(body: string): Promise<any> {
+  private async apply<T = unknown>(body: string): Promise<T> {
     const element = await this.resolve();
-    if (!element) return this.page.evaluate(`(() => { const el = null; ${body} })()`);
+    if (!element) return this.page.evaluate<T>(`(() => { const el = null; ${body} })()`);
     try {
       const result = await this.page.sendTo(element.sessionId, "Runtime.callFunctionOn", {
         objectId: element.objectId,
@@ -799,22 +823,20 @@ export class Locator {
       const { quads } = await this.page
         .sendTo(sessionId, "DOM.getContentQuads", { objectId })
         .catch(() => ({ quads: [] }));
-      const quad = (quads as number[][]).find((q) => area(q) > 0);
+      const quad = (quads as Quad[]).find((q) => area(q) > 0);
       if (!quad) throw new Error("Element is not visible");
+      const [x1, y1, x2, y2, x3, y3, x4, y4] = quad;
       const offset = await this.page.offsetOf(sessionId);
       return {
-        x: offset.x + (quad[0]! + quad[2]! + quad[4]! + quad[6]!) / 4,
-        y: offset.y + (quad[1]! + quad[3]! + quad[5]! + quad[7]!) / 4,
+        x: offset.x + (x1 + x2 + x3 + x4) / 4,
+        y: offset.y + (y1 + y2 + y3 + y4) / 4,
       };
     });
   }
 }
 
-function area(quad: number[]): number {
-  let sum = 0;
-  for (let i = 0; i < 8; i += 2) {
-    const [x1, y1, x2, y2] = [quad[i]!, quad[i + 1]!, quad[(i + 2) % 8]!, quad[(i + 3) % 8]!];
-    sum += x1 * y2 - x2 * y1;
-  }
-  return Math.abs(sum) / 2;
+function area([x1, y1, x2, y2, x3, y3, x4, y4]: Quad): number {
+  return (
+    Math.abs(x1 * y2 - x2 * y1 + x2 * y3 - x3 * y2 + x3 * y4 - x4 * y3 + x4 * y1 - x1 * y4) / 2
+  );
 }
diff --git a/packages/mcp-server/src/browse/selectors.ts b/packages/mcp-server/src/browse/selectors.ts
index 8385f6f..bea8f56 100644
--- a/packages/mcp-server/src/browse/selectors.ts
+++ b/packages/mcp-server/src/browse/selectors.ts
@@ -67,6 +67,7 @@ export function resolveSelector(selector: string, refMaps: RefMaps): ResolvedSel
         `(this program has ${known}).`,
     );
   }
-  const frame = refMaps.frameMap[ref.split("-")[0]!];
+  const [frameIndex = ""] = ref.split("-");
+  const frame = refMaps.frameMap[frameIndex];
   return frame ? { selector: xpath, frame } : { selector: xpath };
 }
diff --git a/packages/mcp-server/src/browse/transport.ts b/packages/mcp-server/src/browse/transport.ts
index d601717..810db2c 100644
--- a/packages/mcp-server/src/browse/transport.ts
+++ b/packages/mcp-server/src/browse/transport.ts
@@ -30,8 +30,15 @@ export const openWebSocket: OpenSocket = (url, signal) =>
     });
   });
 
+/**
+ * A decoded CDP message body. Payloads arrive as unvalidated JSON, and callers
+ * read only the fields their command documents.
+ */
+// biome-ignore lint/suspicious/noExplicitAny: the wire format is untyped; typing every CDP domain is out of scope.
+export type CdpPayload = any;
+
 type Pending = {
-  resolve(value: any): void;
+  resolve(value: CdpPayload): void;
   reject(error: Error): void;
   timer: ReturnType<typeof setTimeout>;
 };
@@ -41,7 +48,7 @@ export class CdpConnection {
   private pending = new Map<number, Pending>();
   private nextId = 0;
   private signal: AbortSignal | undefined;
-  private listeners = new Set<(method: string, params: any, sessionId?: string) => void>();
+  private listeners = new Set<(method: string, params: CdpPayload, sessionId?: string) => void>();
   private abort = () => this.close();
   constructor(socket: WebSocket, signal?: AbortSignal) {
     this.socket = socket;
@@ -66,11 +73,11 @@ export class CdpConnection {
     if (signal?.aborted) this.close();
   }
 
-  onEvent(listener: (method: string, params: any, sessionId?: string) => void) {
+  onEvent(listener: (method: string, params: CdpPayload, sessionId?: string) => void) {
     this.listeners.add(listener);
   }
 
-  send<T = any>(method: string, params: object = {}, sessionId?: string): Promise<T> {
+  send<T = CdpPayload>(method: string, params: object = {}, sessionId?: string): Promise<T> {
     this.signal?.throwIfAborted();
     if (this.socket.readyState !== 1) return Promise.reject(new Error("CDP connection is closed."));
     return new Promise<T>((resolve, reject) => {
diff --git a/packages/mcp-server/tests/frames.e2e.test.ts b/packages/mcp-server/tests/frames.e2e.test.ts
index 2170fa1..550aeb7 100644
--- a/packages/mcp-server/tests/frames.e2e.test.ts
+++ b/packages/mcp-server/tests/frames.e2e.test.ts
@@ -91,7 +91,8 @@ test("the snapshot includes every frame, cross-site and nested ones too", {
   const lines = tree.split("\n");
   const iframe = lines.findIndex((l) => l.includes("Iframe: Cross-site frame"));
   const button = lines.findIndex((l) => l.includes("button: Cross-site button"));
-  assert.ok(button > iframe && lines[button]!.search(/\S/) > lines[iframe]!.search(/\S/));
+  const indent = (index: number) => lines[index]?.search(/\S/) ?? -1;
+  assert.ok(iframe !== -1 && button > iframe && indent(button) > indent(iframe));
   assert.ok(!tree.includes("InlineTextBox"));
   assert.ok(!tree.includes("StaticText: Top button"));
 });
diff --git a/packages/mcp-server/tests/lifecycle.test.ts b/packages/mcp-server/tests/lifecycle.test.ts
index e957132..46d76a4 100644
--- a/packages/mcp-server/tests/lifecycle.test.ts
+++ b/packages/mcp-server/tests/lifecycle.test.ts
@@ -41,7 +41,7 @@ test("provider shutdown still runs when CDP disconnect throws", async () => {
 });
 
 test("a serialized handle can be shut down on a fresh instance", async () => {
-  const stopped: string[] = [];
+  const stopped: Array<string | undefined> = [];
   const provider = () =>
     browserProvider({
       name: "test",
@@ -50,7 +50,7 @@ test("a serialized handle can be shut down on a fresh instance", async () => {
         cdpUrl: "wss://browser.example/session-1",
       }),
       shutdown: async (browser) => {
-        stopped.push(browser.sessionId!);
+        stopped.push(browser.sessionId);
       },
     });
   const create = createApp({ config: loadConfig(), provider: provider() });
@@ -111,7 +111,7 @@ for (const name of ["kernel", "browserbase"]) {
     assert.equal(name === "kernel" ? body.timeout_seconds : body.timeout, 600);
     if (name === "browserbase") assert.equal(body.keepAlive, true);
     await providerFromEnv(env, request).shutdown(JSON.parse(JSON.stringify(handle)));
-    assert.match(calls[1]!.url, /\/one$/);
+    assert.match(calls[1]?.url ?? "", /\/one$/);
     assert.equal(calls[1]?.init?.method, name === "kernel" ? "DELETE" : "POST");
   });
 }
diff --git a/packages/mcp-server/tests/mcp.test.ts b/packages/mcp-server/tests/mcp.test.ts
index 8369484..4c1485a 100644
--- a/packages/mcp-server/tests/mcp.test.ts
+++ b/packages/mcp-server/tests/mcp.test.ts
@@ -215,7 +215,7 @@ test("health reports the stateless deployment", async () => {
 test("a provider supplies the browser and is released after the program", async () => {
   // Stands in for a hosted provider: create a session on acquire, end it after.
   const acquired: string[] = [];
-  const released: string[] = [];
+  const released: Array<string | undefined> = [];
 
   const config = loadConfig({} as NodeJS.ProcessEnv);
   const app = createApp({
@@ -233,7 +233,7 @@ test("a provider supplies the browser and is released after the program", async
         };
       },
       async shutdown(browser) {
-        released.push(browser.sessionId!);
+        released.push(browser.sessionId);
       },
     },
     connect: async () => createFakeBrowser(),
diff --git a/packages/tools/src/index.ts b/packages/tools/src/index.ts
index 96899ad..e2e96a8 100644
--- a/packages/tools/src/index.ts
+++ b/packages/tools/src/index.ts
@@ -110,8 +110,9 @@ export function createBrowserToolkit(options: BrowserToolsOptions = {}) {
     ...(options.connect ? { connect: options.connect } : {}),
     ...(options.run ? { run: options.run } : {}),
   };
-  const notify = options.onEvent
-    ? (level: BrowserEvent["level"], data: unknown) => options.onEvent!({ level, data })
+  const { onEvent } = options;
+  const notify = onEvent
+    ? (level: BrowserEvent["level"], data: unknown) => onEvent({ level, data })
     : undefined;
 
   const sessionIdInput = z.object({
@@ -246,7 +247,7 @@ function temporarySessions(browser: Browser): BrowserProvider {
       return { provider: session.provider, cdpUrl: session.cdpUrl, sessionId: session.id };
     },
     async shutdown(handle) {
-      await browser.stop(handle.sessionId!);
+      if (handle.sessionId) await browser.stop(handle.sessionId);
     },
   };
 }
diff --git a/packages/tools/tests/tools.test.ts b/packages/tools/tests/tools.test.ts
index f733687..a6b3117 100644
--- a/packages/tools/tests/tools.test.ts
+++ b/packages/tools/tests/tools.test.ts
@@ -81,7 +81,9 @@ test("AI SDK: the model runs a program and reads the compact result text", async
   assert.deepEqual(state.endpoints, ["ws://fake"]);
   assert.equal(state.closed, 1);
 
-  const output = result.steps[0]!.toolResults[0]!.output as BrowserRunOutput;
+  const toolResult = result.steps[0]?.toolResults[0];
+  assert.ok(toolResult);
+  const output = toolResult.output as BrowserRunOutput;
   assert.equal(output.status, "completed");
   assert.equal(output.value, "Fake");
 
@@ -93,14 +95,19 @@ test("AI SDK: the model runs a program and reads the compact result text", async
 
 test("AI SDK: a failed program is reported to the model as an error", async () => {
   const { connect } = fakeBrowser();
-  const tools = aiSdkTools({ cdpUrl: "ws://fake", connect, env: {} });
-  const output = (await tools.browser_run.execute!(
+  const { execute, toModelOutput } = aiSdkTools({
+    cdpUrl: "ws://fake",
+    connect,
+    env: {},
+  }).browser_run;
+  assert.ok(toModelOutput);
+  const output = (await execute(
     { code: `await browse.back();` },
     { toolCallId: "1", messages: [], context: {} },
   )) as BrowserRunOutput;
   assert.equal(output.isError, true);
   assert.match(output.text, /unexpected command back/);
-  const modelOutput = await tools.browser_run.toModelOutput!({
+  const modelOutput = await toModelOutput({
     toolCallId: "1",
     input: { code: "" },
     output,
@@ -113,12 +120,13 @@ test("Mastra: tools share ids, descriptions, and execution", async () => {
   const tools = mastraTools({ cdpUrl: "ws://fake", connect, env: {} });
   assert.equal(tools.browser_run.id, "browser_run");
   assert.match(tools.browser_run.description, /Evaluate a TypeScript program/);
+  assert.ok(tools.browser_api.execute && tools.browser_run.execute);
   assert.match(
-    (await tools.browser_api.execute!({}, {} as never)) as string,
+    (await tools.browser_api.execute({}, {} as never)) as string,
     /declare const browse/,
   );
 
-  const output = (await tools.browser_run.execute!(
+  const output = (await tools.browser_run.execute(
     { code: `return (await browse.get("title")).title;` },
     {} as never,
   )) as BrowserRunOutput;
@@ -143,7 +151,7 @@ test("without cdpUrl, each program leases and releases a provider browser", asyn
       },
     },
   });
-  await tools.browser_run.execute!(
+  await tools.browser_run.execute(
     { code: `return 1;` },
     { toolCallId: "1", messages: [], context: {} },
   );
@@ -154,7 +162,7 @@ test("without cdpUrl, each program leases and releases a provider browser", asyn
 test("with a Browser, the model starts a session, drives it by id, watches it, and stops it", async () => {
   const { state, connect } = fakeBrowser();
   let created = 0;
-  const shutdowns: string[] = [];
+  const shutdowns: Array<string | undefined> = [];
   const browser = providerBrowser(
     {
       name: "test",
@@ -163,7 +171,7 @@ test("with a Browser, the model starts a session, drives it by id, watches it, a
         return { provider: "test", cdpUrl: `ws://session-${created}`, sessionId: `s${created}` };
       },
       async shutdown(handle) {
-        shutdowns.push(handle.sessionId!);
+        shutdowns.push(handle.sessionId);
       },
     },
     {
@@ -177,31 +185,37 @@ test("with a Browser, the model starts a session, drives it by id, watches it, a
   );
   const tools = aiSdkTools({ browser, connect, env: {} });
   const options = { toolCallId: "1", messages: [], context: {} };
+  const run = tools.browser_run.execute;
+  const start = tools.browser_start?.execute;
+  const stop = tools.browser_stop?.execute;
+  const list = tools.browser_list_sessions?.execute;
+  const liveView = tools.browser_live_view;
+  assert.ok(start);
+  assert.ok(stop);
+  assert.ok(list);
+  assert.ok(liveView?.toModelOutput);
 
   // The CDP URL is a credential: it never reaches the model.
   assert.doesNotMatch(JSON.stringify(tools.browser_run.inputSchema), /cdpUrl/);
-  const started = await tools.browser_start!.execute!({}, options);
+  const started = await start({}, options);
   assert.deepEqual(Object.keys(started).sort(), ["id", "provider", "startedAt"]);
-  await tools.browser_start!.execute!({}, options);
+  await start({}, options);
 
-  const first = (await tools.browser_run.execute!(
-    { code: `return 1;`, sessionId: "s1" },
-    options,
-  )) as BrowserRunOutput;
-  await tools.browser_run.execute!({ code: `return 1;` }, options);
+  const first = (await run({ code: `return 1;`, sessionId: "s1" }, options)) as BrowserRunOutput;
+  await run({ code: `return 1;` }, options);
   assert.match(first.text, /· session s1\n/);
   assert.doesNotMatch(JSON.stringify(first), /ws:\/\//);
   assert.deepEqual(state.endpoints, ["ws://session-1", "ws://session-2"]);
 
-  const unknown = (await tools.browser_run.execute!(
+  const unknown = (await run(
     { code: `return 1;`, sessionId: "nope" },
     options,
   )) as BrowserRunOutput;
   assert.equal(unknown.isError, true);
   assert.match(unknown.text, /Unknown browser session: nope/);
 
-  const view = (await tools.browser_live_view!.execute!({ sessionId: "s1" }, options)) as LiveView;
-  const viewOutput = await tools.browser_live_view!.toModelOutput!({
+  const view = (await liveView.execute({ sessionId: "s1" }, options)) as LiveView;
+  const viewOutput = await liveView.toModelOutput({
     toolCallId: "1",
     input: { sessionId: "s1" },
     output: view,
@@ -209,8 +223,8 @@ test("with a Browser, the model starts a session, drives it by id, watches it, a
   assert.equal(viewOutput.type, "content");
   assert.match(JSON.stringify(viewOutput), /"mediaType":"image\/jpeg".*"SlBFRw=="/);
 
-  await tools.browser_stop!.execute!({ sessionId: "s1" }, options);
-  const { sessions } = (await tools.browser_list_sessions!.execute!({}, options)) as {
+  await stop({ sessionId: "s1" }, options);
+  const { sessions } = (await list({}, options)) as {
     sessions: SessionSummary[];
   };
   assert.deepEqual(
@@ -234,7 +248,8 @@ test("with a Browser and no open session, browser_run uses a temporary one", asy
     },
   });
   const tools = mastraTools({ browser, connect, env: {} });
-  await tools.browser_run.execute!({ code: `return 1;` }, {} as never);
+  assert.ok(tools.browser_run.execute);
+  await tools.browser_run.execute({ code: `return 1;` }, {} as never);
   assert.deepEqual(lifecycle, ["create", "shutdown"]);
   assert.deepEqual(state.endpoints, ["ws://temporary"]);
   assert.deepEqual(await browser.listSessions(), []);

From 452a70901d46d48eadd4736970f8e80a17b715d6 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 24 Sep 2026 15:15:40 +0000
Subject: [PATCH 4/6] Run Biome in a pre-push hook and fail on warnings

---
 README.md           |  5 ++++-
 package.json        | 11 ++++++++---
 pnpm-lock.yaml      |  9 +++++++++
 pnpm-workspace.yaml |  4 +++-
 4 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index fb864ca..9c58f64 100644
--- a/README.md
+++ b/README.md
@@ -270,7 +270,10 @@ pnpm test:e2e  # existing browser on BROWSE_CDP_URL or port 9222
 
 `pnpm check` runs [Biome](https://biomejs.dev) (lint, formatting, import order)
 before type-checking every package. `pnpm lint:fix` applies Biome's safe fixes
-and formatting; `pnpm format` only formats.
+and formatting; `pnpm format` only formats. Biome warnings fail the check.
+
+`pnpm install` adds a pre-push hook that runs `pnpm lint`, and CI runs the same
+check on every pull request. Set `SKIP_SIMPLE_GIT_HOOKS=1` to skip the hook.
 
 The runtime suites start an isolated Chrome and exercise real MCP execution,
 TypeScript, snapshot-ref clicks, loop interruption, screenshots, and lifecycle
diff --git a/package.json b/package.json
index c529182..bddae41 100644
--- a/package.json
+++ b/package.json
@@ -10,8 +10,8 @@
   "packageManager": "pnpm@11.10.0",
   "scripts": {
     "build": "pnpm -r build",
-    "check": "biome check . && pnpm -r check",
-    "lint": "biome check .",
+    "check": "pnpm lint && pnpm -r check",
+    "lint": "biome check --error-on-warnings .",
     "lint:fix": "biome check --write .",
     "format": "biome format --write .",
     "test": "pnpm -r --if-present test",
@@ -21,11 +21,16 @@
     "dev:server": "pnpm --filter @browse-code-mode/mcp-server dev",
     "dev:web": "pnpm --filter @browse-code-mode/web dev",
     "chrome": "node scripts/chrome.mjs",
-    "example": "node scripts/example.mjs"
+    "example": "node scripts/example.mjs",
+    "prepare": "simple-git-hooks"
+  },
+  "simple-git-hooks": {
+    "pre-push": "pnpm lint"
   },
   "devDependencies": {
     "@biomejs/biome": "2.5.14",
     "@types/node": "^22.19.0",
+    "simple-git-hooks": "2.14.0",
     "typescript": "^5.9.3"
   }
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 8432ba8..ddddb3c 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -14,6 +14,9 @@ importers:
       '@types/node':
         specifier: ^22.19.0
         version: 22.20.4
+      simple-git-hooks:
+        specifier: 2.14.0
+        version: 2.14.0
       typescript:
         specifier: ^5.9.3
         version: 5.9.3
@@ -2874,6 +2877,10 @@ packages:
     resolution: {integrity: sha512-bzyZ1e88w9O1iNJbKnOlvYTrWPDl46O1bG0D3XInv+9tkPrxrN8jUUTiFlDkkmKWgn1M6CfIA13SuGqOa9Korw==}
     engines: {node: '>=14'}
 
+  simple-git-hooks@2.14.0:
+    resolution: {integrity: sha512-kkTORPAuxQz2g1QUuN0J8yGWT28tjGBfPOdJ4xT7Vbeu30veKUZQIoID2qGgCDAakaQn59UeZJJ4cFGB8PVP2A==}
+    hasBin: true
+
   source-map-js@1.2.1:
     resolution: {integrity: sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==}
     engines: {node: '>=0.10.0'}
@@ -5981,6 +5988,8 @@ snapshots:
 
   signal-exit@4.1.0: {}
 
+  simple-git-hooks@2.14.0: {}
+
   source-map-js@1.2.1: {}
 
   source-map@0.7.6: {}
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
index 1dfddb6..1edea2c 100644
--- a/pnpm-workspace.yaml
+++ b/pnpm-workspace.yaml
@@ -4,7 +4,9 @@ packages:
   - examples/*
 
 # esbuild's platform binary arrives through its optional dependencies, so its
-# install script is not needed. Declined explicitly so installs do not prompt.
+# install script is not needed. simple-git-hooks is installed by the root
+# `prepare` script instead. Declined explicitly so installs do not prompt.
 allowBuilds:
   esbuild: false
+  simple-git-hooks: false
   workerd: true

From 41553eadc4fb42a8e6ea695e161aab8b54575fe5 Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 24 Sep 2026 15:15:40 +0000
Subject: [PATCH 5/6] Add CI workflow running biome ci

---
 .github/workflows/ci.yml | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 .github/workflows/ci.yml

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..5ca67f6
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,18 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  biome:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      # Picks up the Biome version pinned in pnpm-lock.yaml.
+      - uses: biomejs/setup-biome@v2
+      - run: biome ci --error-on-warnings .

From db912ba744a8168cd997add3b916d39b0551da5e Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Thu, 24 Sep 2026 16:03:42 +0000
Subject: [PATCH 6/6] Build, type-check, and run unit tests in CI

---
 .github/workflows/ci.yml | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5ca67f6..e46d3d5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,3 +16,19 @@ jobs:
       # Picks up the Biome version pinned in pnpm-lock.yaml.
       - uses: biomejs/setup-biome@v2
       - run: biome ci --error-on-warnings .
+
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      # Installs the pnpm pinned in packageManager, then runs pnpm install.
+      # Tests run .ts files directly, which needs Node 22.18 or newer.
+      - uses: pnpm/setup@v3
+        with:
+          runtime: node@22
+          cache: true
+          require-lockfile: true
+      # The web app's type-check imports routeTree.gen.ts, which the build generates.
+      - run: pnpm build
+      - run: pnpm -r check
+      - run: pnpm test