{
  "slug": "wrangler-dev-supports-experimental-headful-browser-rendering-604eedae65d4",
  "title": "wrangler dev supports experimental headful browser rendering",
  "tools": [
    "wrangler"
  ],
  "tags": [
    "agent"
  ],
  "introduced_at": "2026-04-02T12:17:02.000Z",
  "announced_at": "2026-04-02T12:17:02.000Z",
  "effective_at": null,
  "date_basis": "source-publication",
  "status": "unknown",
  "how": {
    "incantation": "When debugging local development with the Browser Rendering API, set `X_BROWSER_HEADFUL=true` before starting `wrangler dev` or `vite dev` to show Chrome. This is experimental; with `@cloudflare/playwright`, two Chrome windows may appear because of browser contexts via CDP.",
    "examples": [
      "X_BROWSER_HEADFUL=true wrangler dev",
      "X_BROWSER_HEADFUL=true vite dev"
    ],
    "gotchas": [
      "Version: 4.80.0",
      "Availability: Experimental; may be removed or changed without notice.",
      "X_BROWSER_HEADFUL=true (required): Environment variable that enables visible (headful) browser mode during local development.",
      "wrangler dev / vite dev (required): Start the local development server with the environment variable set before the command.",
      "Prerequisite: Use for local development with the Browser Rendering API; the feature is experimental and may change or be removed.",
      "When using `@cloudflare/playwright`, two Chrome windows may appear: an initial blank page and the page created by `browser.newPage()`. This is expected behavior due to how Playwright handles browser contexts via CDP."
    ]
  },
  "why_it_matters": "Debug local development that uses the Browser Rendering API by viewing its browser window.",
  "sources": [
    "https://github.com/cloudflare/workers-sdk/releases/tag/wrangler%404.80.0",
    "https://github.com/cloudflare/workers-sdk/releases/tag/wrangler@4.80.0",
    "https://developers.cloudflare.com/browser-run/faq/"
  ],
  "rank": 0.92017,
  "judge": {
    "publish": true,
    "judge_model": "codex-cli/gpt-6-luna+typesafe/jev-1.13.0",
    "prompt_version": "extract-v7+enrich-v1+judge-v2x3+jev-publish-v1"
  },
  "review_state": "approved",
  "provenance": {
    "run_id": "backfill-20261007",
    "verdict_id": "backfill-20261007:backfill-20261007-6e5b9cae32949ffa-1:gate",
    "evidence_hash": "61340fd593c1bbe957014b28a038cb5f7b969ca660dc4e91cd7857550a809918"
  },
  "review": {
    "draft_hash": "159d8f99b1a5809fc11621f53a487d6e0afa76b6ba2104649039a25adfab0cf2",
    "reviewer": "publication-gate",
    "reviewed_at": "2026-10-07T00:00:00.000Z",
    "decision": "backfill-20261007:gate",
    "reason": "3 of 3 judge runs approved with p_yes >= 0.9 (mean 0.92 >= 0.9; 2 needed) and Jev gave 0.67 (>= 0.6 needed)."
  }
}