Add local browser mode as an automatic fallback when Browserbase
credentials are not configured. Uses the same agent-browser CLI with
--session (local Chromium) instead of --cdp (cloud Browserbase).
The agent-facing API is completely unchanged — all 10 browser_* tools
produce identical output in both modes. Auto-detection:
- BROWSERBASE_API_KEY set → cloud mode (existing behavior)
- No key → local mode (new, free, headless Chromium)
Changes:
- _is_local_mode(): auto-detect based on env vars
- _create_local_session(): lightweight session (no API call)
- _get_session_info(): branches on local vs cloud
- _run_browser_command(): --session in local, --cdp in cloud
- check_browser_requirements(): only needs agent-browser CLI in local mode
- _emergency_cleanup: CLI close in local, API release in cloud
- cleanup_browser/browser_close: skip BB API calls in local mode
- Registry: removed requires_env — check_fn handles both modes
Setup for local mode:
npm install -g agent-browser
agent-browser install # downloads Chromium
agent-browser install --with-deps # also installs system libs (Docker/Debian)
Closes#374 (Phase 1)