feat(mcp): add playwright preset to hermes mcp add - #63771
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Adds @playwright/mcp to the built-in MCP preset registry alongside the existing codex preset (issue NousResearch#19760). Key design decisions (addressing maintainer review of PR NousResearch#19768): - codex preset is preserved; both entries coexist in _MCP_PRESETS - _playwright_browser_args() uses platform-aware detection via shutil.which() across the common Chrome/Chromium binary names (google-chrome, google-chrome-stable, chromium-browser, chromium, chrome) instead of a single /opt/google/chrome/chrome path that would misclassify PATH installs, /usr/bin installs, snap packages, macOS, and Windows as 'browser absent' - --no-sandbox added only on Linux when euid==0 (root/VPS/Docker) - --browser=chromium fallback added only when NO system browser is found on the current PATH (so default Playwright behavior is preserved for normal user installs) 7 tests in TestPlaywrightMcpPreset: - playwright registered alongside codex - preset uses npx command - --no-sandbox on Linux root - --no-sandbox NOT added on macOS - --browser=chromium added when no system browser found - --browser=chromium NOT added when google-chrome on PATH - /usr/bin/chromium-browser also counts as system browser Fixes NousResearch#19760
Documents the new playwright preset in the built-in-presets table at website/docs/user-guide/features/mcp.md, including the root/VPS --no-sandbox behavior and the Playwright bundled Chromium fallback.
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teknium1
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Jul 16, 2026
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Thanks for preserving the existing codex preset and adding focused tests and MCP documentation.
Problems
hermes_cli/mcp_config.py:68only usesshutil.which()to decide whether a browser exists. That still misses standard macOS app bundles and Windows install directories; current main'shermes_cli/browser_connect.py:22-124explicitly checks those platform locations. The forced fallback can therefore change behavior for ordinary non-PATH browser installs.- The PR body says
Fixes #19760, but #19760 is the closed NixnpmDepsHashreport, not a Playwright MCP request.
Suggested changes
- Use an equivalent platform-aware resolver (and add macOS/Windows non-PATH tests), or retain the upstream standard
npx @playwright/mcp@latestarguments rather than forcing a browser choice. - Correct the issue linkage.
Automated hermes-sweeper review.
| "chromium-browser", "chromium", | ||
| "chrome", | ||
| ) | ||
| _found_system_browser = any(shutil.which(name) for name in _chrome_names) |
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shutil.which() alone still reports no browser for standard macOS app-bundle installs and Windows install locations. hermes_cli/browser_connect.py:22-124 covers those paths; use equivalent platform-aware detection (with macOS/Windows regressions), or avoid forcing the fallback.
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…eset Per teknium1's review of NousResearch#63771 ('add macOS/Windows non-PATH tests'), only the macOS .app-bundle case was added. Add the matching Windows standard-install-directory case, confirming the platform-aware get_chrome_debug_candidates() resolver -- not a bare shutil.which() name list -- is what determines browser availability on Windows too. 68/68 tests pass in tests/hermes_cli/test_mcp_config.py.
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Problem
hermes mcp add had no playwright preset (issue #19760). Previous PR #19768 added it but used a single /opt/google/chrome path check (classifying PATH installs, /usr/bin, macOS, Windows as browser absent) and dropped the codex preset.
Fix
Verification
7 tests in TestPlaywrightMcpPreset: preset registered, npx command, --no-sandbox on Linux root, not on macOS, chromium fallback when absent, no fallback when found, /usr/bin/chromium-browser counts. 7/7 pass.
Fixes #19760