Capture closed Shadow DOM

Closed roots deliberately return null through element.shadowRoot. Domstamp can capture author-created closed roots only when a Playwright preload observes their creation.

Install before navigation

import { chromium } from 'playwright';
import { createDomstamp } from 'domstamp';
import {
  installClosedShadowInstrumentation,
  playwrightAdapter
} from '@domstamp/playwright';

const browser = await chromium.launch();
const context = await browser.newContext();
const closedShadowRoots = await installClosedShadowInstrumentation(context);
const page = await context.newPage();

const domstamp = createDomstamp(playwrightAdapter({ closedShadowRoots }));

await page.goto('https://example.com');
const snapshot = await domstamp.capture(page, {
  features: { dom: { shadowRoots: 'all-available' } }
});

Install the preload before creating or navigating pages. Installing it after a document has created closed roots cannot recover those earlier references.

Read the provenance

Schema 3 adds one closed-shadow-dom evidence record per captured frame:

const coverage = snapshot.evidence.filter(
  (entry) => entry.kind === 'closed-shadow-dom'
);

for (const entry of coverage) {
  console.log(entry.frameId, entry.completeness, entry.details.capturedRoots);
}

Expected fields:

• source: preload-instrumentation.
• completeness: instrumented, or unavailable when a frame could not expose the preload.
• privilege: instrumented.
• sensitivity: sensitive.
• details.capturedRoots: closed roots represented in that frame document.
• details.instrumentationAvailable: whether the registry accessor existed during capture.

instrumented means every root retained by the preload was eligible for capture. It does not mean the browser exposed every possible closed or user-agent root.

Traversal and limits

Instrumented roots use ordinary bounded traversal. Nested and dynamically created roots participate in maxNodesPerFrame, maxDepth, focus scope, mutation consistency, structural redaction, validation, and TQ1 round trips. The s path segment crosses both open and instrumented closed-root boundaries.

Cross-origin frames receive the same context preload. Each frame keeps its own evidence record, so a missing instrument cannot be mistaken for an empty frame.

Dispose deliberately

await closedShadowRoots.dispose();

Disposal removes the preload from future documents. Documents that already executed it remain instrumented until they are discarded or navigated.

Non-claims

The instrumented path does not promise access to:

• roots created before installation;
• browser-owned user-agent shadow trees;
• a page that replaces or defeats the hook;
• browser chrome, extension UI, or JavaScript heap state.

Use an isolated browser context. Treat closed-root content as sensitive and exercise the same sentinel-redaction tests used for light DOM.