vscode-dev-workbench

name	vscode-dev-workbench
description	Use when the user wants to run the vscode.dev server locally and exercise the VS Code web workbench in the integrated browser against local VS Code sources. Covers starting the dev server, the `vscode-quality=dev` URL, browser-driven interaction patterns, mobile emulation, reloads, and troubleshooting.

Running vscode.dev Against Local VS Code Sources

The vscode-dev repo is the vscode.dev server. When run locally with ?vscode-quality=dev, it serves the VS Code web workbench from the sibling vscode checkout. This is the fastest way to validate web-only changes to the workbench without shipping an Insiders build.

Layout assumption

vscode-dev and vscode must be sibling folders:

<workRoot>/
  vscode/          # microsoft/vscode checkout
  vscode-dev/      # microsoft/vscode-dev checkout

If your paths differ, check server/ in vscode-dev for the source root resolution — the /vscode-sources/* route maps to ../vscode.

Start the dev server

Critical: Run npm run dev from the vscode-dev folder, NOT from vscode. The vscode repo has no dev script and will fail with npm error Missing script: "dev". Terminal tools that simplify/strip leading cd into separate commands will silently keep the cwd of a previous terminal — always use an absolute pushd or verify with pwd before npm run dev.

cd /path/to/vscode-dev     # NOT /path/to/vscode
npm run dev                # runs watch + nodemon; serves https://127.0.0.1:3000

If you're driving this through an agent/terminal tool, prefer:

pushd /absolute/path/to/vscode-dev >/dev/null && pwd && npm run dev

On first start you may see one crash like Cannot find module './indexes' — it's the watcher racing the first build. nodemon restarts automatically once out/ finishes compiling. The server is ready when curl -sk -o /dev/null -w "%{http_code}" https://127.0.0.1:3000/ returns 200.

URLs

• https://127.0.0.1:3000/?vscode-quality=dev — main workbench, local dev sources
• https://127.0.0.1:3000/?vscode-version=<commit> — pinned production commit
• Add &vscode-log=trace for verbose client logging

Interacting via the integrated browser

Use open_browser_page and the standard browser tools.

Hard-reloading after a rebuild

The service worker caches client assets aggressively. A plain reload can still serve stale modules:

await page.evaluate(async () => {
  const regs = await navigator.serviceWorker?.getRegistrations() ?? [];
  await Promise.all(regs.map(r => r.unregister()));
  const keys = await caches?.keys() ?? [];
  await Promise.all(keys.map(k => caches.delete(k)));
});
await page.reload({ waitUntil: 'domcontentloaded' });

Simulating mobile (only when explicitly requested)

The integrated browser panel clamps width, so page.setViewportSize() and CDP setDeviceMetricsOverride narrow the viewport only as far as the panel allows. User-Agent override and touch emulation work fine:

const client = await page.context().newCDPSession(page);
await client.send('Emulation.setUserAgentOverride', {
  userAgent: 'Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1',
  platform: 'iPhone'
});
await client.send('Emulation.setTouchEmulationEnabled', { enabled: true, maxTouchPoints: 5 });
await client.send('Emulation.setDeviceMetricsOverride', {
  width: 393, height: 852, deviceScaleFactor: 3, mobile: true,
  screenOrientation: { type: 'portraitPrimary', angle: 0 }
});
await page.reload();

For a true mobile viewport, drive a standalone Playwright script with devices['iPhone 14 Pro'] instead of the integrated browser. If a mobile-responsive overlay intercepts pointer events during automation, fall back to { force: true } on click().

Known-noise console messages (ignore)

• Canceled: Canceled at clipboardService.js — cancelled permission probes on hover.
• NotAllowedError: Failed to execute 'write' on 'Clipboard' — web clipboard requires a user gesture.
• The web worker extension host is started in a same-origin iframe! — expected in dev.
• Unrecognized feature: 'local-network-access' — dev manifest warning.
• [LEAKED DISPOSABLE] stacks — GC-based tracker; only real if reproducible across reloads.

Troubleshooting

Symptom	Cause	Fix
Cannot find module './indexes' on first run	nodemon started before TS compile finished	Wait; it auto-restarts
Workspace picker opens native dialog and hangs automation	Select Folder… needs a real file dialog	Pick a workspace URL scheme instead, or skip in automation
Stale UI after editing vscode/ sources	Service worker cache	Unregister SWs + clear caches (snippet above)