fix(browser): strip PYTHONPATH/PYTHONHOME from browser-use CLI subprocess env (salvage #83471)

[teknium1]

Summary

browser_exec no longer crashes with pydantic_core ABI mismatch / ModuleNotFoundError when the parent process carries PYTHONPATH/PYTHONHOME — the browser-use CLI subprocess env now strips both, so the CLI's own interpreter resolves its own packages.

Root cause: the CLI runs under its own Python (uv tool / uvx), but a child interpreter honors inherited PYTHONPATH/PYTHONHOME ahead of its own site-packages — importing C-extensions built for Hermes's venv interpreter. Hit the desktop backend on py3.14 and any shell exporting PYTHONPATH.

Fixes #83427, #84841, #86006, #86104.

Salvage of #83471 by @n1majne3 (earliest of two independent fixes; #84022 by @jklance16 covered PYTHONPATH only) — the contributor branch bundled unrelated desktop commits via a merge, so the browser hunk was surgically reapplied with authorship preserved.

Changes

• tools/browser_use_cli.py: _base_subprocess_env() pops PYTHONPATH and PYTHONHOME.
• tests/tools/test_browser_use_cli.py: regression test — both vars stripped, unrelated env preserved (the test shape suggested in fix(browser): strip PYTHONPATH/PYTHONHOME from browser-use CLI subprocess env #83471's review).

Validation

	Before	After
desktop backend, py3.14	pydantic_core ABI crash	clean run
shell exports PYTHONPATH	ModuleNotFoundError	clean run
tests/tools/test_browser_use_cli.py	—	85/85 passing

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⚠️ Warnings

CI timings · View report · View job

Wall time 7m38s vs 5m22s (+42.2%). 12 job(s) slower, 10 faster, 2 unchanged.

• Python tests / Run tests slice 3/12: +33.0s
• OS-specific tests / macOS-only tests: +21.0s
• Python tests / Run tests slice 12/12: +20.0s
• Python tests / Run tests slice 4/12: +16.0s
• Python tests / Run tests slice 11/12: -16.0s

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OSV vulnerability scan · View job

5 known vulnerabilities found in pinned dependencies.

• CVE-2026-67213 in package-lock.json
• CVE-2026-67213 in website/package-lock.json
• CVE-2026-70608 in package-lock.json
• CVE-2026-56876 in package-lock.json
• CVE-2026-70606 in package-lock.json

How to fix:

Review the findings in the Security tab. Update the affected dependencies if a patched version is available.