Motivation

Create a clean isolation layer between SDK code and native browser APIs. The long-term goal is to scope BrowserStack unit tests exclusively to this package — all other packages can then run without real-browser testing since their browser API access goes through testable wrappers.

Changes

New package: @datadog/browser-native

Zero-dependency package at the base of the dependency graph (below @datadog/browser-core). Exposes native browser API callsites as standalone named functions, matching browser API names where applicable and using a getter/setter convention for property accesses.

Exports:

• fetch / sendBeacon — network APIs (with Zone.js bypass for fetch)
• addEventListener / removeEventListener — event APIs (with Zone.js bypass + EventTarget.prototype pattern)
• getCookie / setCookie — document.cookie accessor
• getReadyState — document.readyState
• getVisibilityState — document.visibilityState
• now — performance.now()

Migration: packages/core/src/browser/

Updated all direct native callsites in core/src/browser/ to import from @datadog/browser-native instead:

• fetch.ts → re-exports fetch from @datadog/browser-native
• cookie.ts → uses getCookie / setCookie
• addEventListener.ts → uses addEventListener / removeEventListener (removes manual listenerTarget computation and getZoneJsOriginalValue calls)
• runOnReadyState.ts → uses getReadyState
• pageMayExitObservable.ts → uses getVisibilityState

Note: Planning artifacts (design doc, implementation plan) are in .planning/plans/. This code was largely AI agent generated.

Test instructions

yarn test:unit
yarn typecheck
yarn lint

All unit tests (3226), typecheck, and lint pass.

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