test(sdk): cover local V4 extension setup

[shrey150]

Summary

• document the managed-local browser setup used by V4 extension installation
• add regression coverage proving branded Chrome remains on the supported post-launch CDP extension path
• leave runtime behavior and every CLI command unchanged

Finding

Branded Chrome ignored the attempted launch-time unpacked-extension flags. Treating the extension as preloaded then made Stagehand wait for a connection that never arrived. The discarded preload experiment is not part of this pull request; managed-local sessions continue to install the packaged extension after launch through CDP.

Refreshed on 2026-08-10 against the current parent and v4-spike commit d7556e9a.

E2E Test Matrix

Command / flow	Observed output	Confidence / sufficiency
2026-08-10 cumulative stack refresh on Chrome Stable 151	pnpm build passed 6/6 tasks; pnpm check passed 11/11 tasks with 0 errors; the full pnpm test graph exited 0, including 17/17 protocol browser tests and 15/15 local SDK browser tests	Proves the updated six-PR stack is compatible with v4-spike d7556e9a across build, static checks, unit tests, and real-browser suites.
Clean coordinated-release tarball consumer at the cumulative tip	Packed workspace Stagehand and Browse, installed both into an empty npm project, opened example.com, produced a snapshot, clicked through to IANA, filled an injected input, and read back published-v4-ok	Proves the intended co-published artifacts work outside the monorepo with a real Chrome session; it does not substitute for a credentialed Browserbase smoke.
corepack pnpm exec vitest run packages/sdk-ts/tests/browser/localBrowser.test.ts	1 file passed; 3/3 tests passed	Isolated proof of the managed-local Chrome setup and post-launch extension path.
Full JavaScript workspace test:unit graph at the final stack	13/13 tasks passed; 1,788 tests passed and 10 todo	Confirms this test-only layer remains compatible with the refreshed parent and every downstream runtime layer.
Python CI-equivalent suite	455 passed, 1 skipped; generation, lock, Ruff format/lint, and ty checks passed	Checks cross-language protocol/runtime drift after the refreshed V4 merge.
Go 1.26.5 CI-equivalent suite with Chrome Stable 151	Generation and embedded-extension drift checks, gofmt, vet, build, generator tests, and live Chrome tests passed	Proves the rebuilt deterministic extension archive is valid and usable by the Go SDK.
Final corepack pnpm build / corepack pnpm check	6/6 build tasks; 11/11 checks; 400 warnings and 0 errors	Proves repository gates pass at the final refreshed stack.

No changeset is included because this pull request changes tests and explanatory comments only.

Final release validation (2026-08-10)

At the cumulative stack tip:

• release validation now recognizes public browse changesets
• a Changesets version dry run resolves browse 0.9.7, Stagehand 4.0.1, extension 1.0.1, and Go 4.0.1
• the packed Browse 0.9.7 manifest rewrites workspace:* to exact Stagehand 4.0.1
• a clean npm consumer installed those versioned tarballs and completed real-Chrome open, snapshot, model-free click, URL read, and stop with zero audit vulnerabilities

[changeset-bot]

⚠️ No Changeset found

Latest commit: b76d6bf

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[shrey150]

Superseded by the clean replacement stack. The extension-facing needs are now implemented as public Stagehand APIs in #2831 (cursor overlay) and #2832 (typed network capture), then consumed and validated by the CLI runtime in #2834. A standalone extension-setup PR is no longer needed. Closing this draft.