sprinter-patchright-compat

Compatibility patch for Patchright when connecting over CDP to a Sprinter browser session.

What It Fixes

Sprinter's CDP gateway emits internal traffic with rewritten or unrelated response IDs (for example 1900000016, or success/error frames for the gateway's own Browser.getVersion warmup). Patchright's CRSession._onMessage asserts on any unmatched id-bearing frame, which crashes the process during chromium.connectOverCDP(...) — typically only on the first run, since a second attempt finds the gateway in steady state.

This package rewrites patchright-core/lib/server/chromium/crConnection.js so the CDP client:

• maps Sprinter's 1900000000 + id response IDs back to the pending Patchright callback,
• silently drops every other id-bearing response (success or error) that Patchright never registered,
• still raises real CDP errors that belong to outstanding Patchright calls.

The wider drop covers all error codes (the previous v0.1 patch only ignored -32001), which is what eliminates the "first run panics, second run works" pattern.

Usage

From a project that has patchright installed:

npx sprinter-patchright-compat

For local development from this checkout:

node bin/sprinter-patchright-compat.js --root /path/to/project

Wire it into a consuming project's package.json so reinstalls don't wipe the patch:

{
  "scripts": {
    "postinstall": "sprinter-patchright-compat"
  }
}

The patcher is idempotent and will upgrade installs that still carry the v0.1 patch.

Auto Viewport

After running npx sprinter-patchright-compat, every page created on a Patchright BrowserContext is automatically pinned to 1920x947 — Sprinter's expected viewport (1080p Xvfb minus chrome's tab + URL bars). Customer code is unchanged:

const { chromium } = require("patchright");

const browser = await chromium.connectOverCDP(sessionUrl);
const context = browser.contexts()[0] || await browser.newContext();
const page = await context.newPage();      // viewport already 1920x947
await page.goto("https://example.com/");

Opt out per-process: SPRINTER_DISABLE_VIEWPORT=1. If a single page needs a different viewport, just call page.setViewportSize(...) after newPage() — the customer's call wins.

For programmatic access (constant, or applying to a page you got via Target.attachedToTarget or another non-newPage path):

const { SPRINTER_VIEWPORT, applyViewport, autoApplyViewport } = require("sprinter-patchright-compat");

Smoke Test

const { chromium } = require("patchright");

(async () => {
  const browser = await chromium.connectOverCDP("ws://127.0.0.1:19012/devtools/browser");
  const context = browser.contexts()[0] || await browser.newContext();
  const page = await context.newPage();
  await page.goto("https://example.com/", { waitUntil: "domcontentloaded" });
  console.log(await page.viewportSize()); // { width: 1920, height: 947 }
  console.log(await page.title());
  await browser.close();
})();

Notes

Both patch sites are runtime modifications of Patchright's generated package files. Treat as narrow compatibility shims until upstream support lands. The patcher is idempotent and self-detects already-patched files.