⚗️ collect Network Efficiency Guardrails document-policy-violation reports as errors

[thomasbertet]

Motivation

Add support for the Network Efficiency Guardrails experimental browser API (currently available in Edge 146+ and Chromium behind the --enable-experimental-web-platform-features flag).

When a page opts in via the Document-Policy: network-efficiency-guardrails header, the browser fires document-policy-violation reports for resources that violate the policy (e.g. uncompressed JS/CSS). This change collects those reports as SDK errors/logs, following the same pattern as csp_violation, intervention, and deprecation.

Jira: PROF-15113

Changes

• browser-core — browser.types.ts: Added DocumentPolicyViolationReport and DocumentPolicyViolationReportBody interfaces; widened Report.body union and ReportType union.
• browser-core — reportObservable.ts: Added RawReportType.networkEfficiencyGuardrails = 'network-efficiency-guardrails'; buildReportObserverTypes() maps it to the document-policy-violation ReportingObserver type; buildRawReportErrorFromReport() handles the new type (filters to NEG featureId, reuses csp.disposition field).
• browser-rum-core — trackReportError.ts: Added networkEfficiencyGuardrails to the subscribed report types so RUM collects these as errors.
• browser-core tests — mockReportingObserver.ts: Added FAKE_DOCUMENT_POLICY_VIOLATION_REPORT fixture. reportObservable.spec.ts: 3 new unit tests (notification, stack trace, featureId filter).
• E2E — mock.ts: Added /?network-efficiency-guardrails=true query param (sets Document-Policy header) and /uncompressed-script.js endpoint. networkEfficiencyGuardrails.scenario.ts: 3 new E2E tests (RUM errors, Logs forwarding ON, Logs forwarding OFF).

Test instructions

E2E tests require Chromium with --enable-experimental-web-platform-features (handled automatically by test.use({ launchOptions }) in the scenario file):

yarn build
yarn test:e2e -g "network efficiency"

Unit tests:

yarn test:unit --spec packages/browser-core/src/domain/report/reportObservable.spec.ts

Checklist

• Tested locally
• Tested on staging
• Added unit tests for this change.
• Added e2e/integration tests for this change.
• Updated documentation and/or relevant AGENTS.md file

[datadog-prod-us1-3]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 82.61%
• Overall Coverage: 76.80% (-0.01%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 9df763e | Docs | Datadog PR Page | Give us feedback!}

[cit-pr-commenter-54b7da]

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	172.04 KiB	172.45 KiB	+424 B	+0.24%	✅
Rum Profiler	8.01 KiB	8.01 KiB	0 B	0.00%	✅
Rum Recorder	21.09 KiB	21.09 KiB	0 B	0.00%	✅
Logs	54.21 KiB	54.70 KiB	+502 B	+0.90%	✅
Rum Slim	129.72 KiB	130.13 KiB	+424 B	+0.32%	✅
Worker	22.96 KiB	22.96 KiB	0 B	0.00%	✅