Monorepo Packages

Browser Packages

playwright-chromium, playwright-firefox, playwright-webkit — per-browser distributions. playwright-browser-chromium, playwright-browser-firefox, playwright-browser-webkit — binary packages.

Tooling Packages

Component Testing

playwright-ct-core, playwright-ct-react, playwright-ct-vue

Key Directories

Build

npm run build       # Full build
npm run watch       # Watch mode (recommended during development)

Assume watch is running and code is up to date. Generated files (types, channels, validators) are produced by watch automatically.

Lint and type check

npm run flint

Runs all lint checks in parallel: eslint, tsc, doclint, check-deps, generate_channels, generate_types, lint-tests, test-types, lint-packages, code-snippet linting.

Always run flint before committing. Do not use tsc --noEmit or individual lint commands separately.

Test Commands

Filtering

npm run ctest tests/page/locator-click.spec.ts         # Specific file
npm run ctest tests/page/locator-click.spec.ts:12      # Specific location
npm run ctest -- --grep "should click"                 # By test name
npm run ctest-mcp snapshot                             # By file name part

Test Directories and Fixtures

Decision rule: Does the test need browser/browserType/context → tests/library/. Just needs page + server → tests/page/.

DEPS System

Import boundaries are enforced via DEPS.list files (52+ across the repo), checked by npm run flint.

Key rule: Client code NEVER imports server code. Server code NEVER imports client code. Communication is only through the protocol. When creating or moving files, update the relevant DEPS.list to declare allowed imports. Files marked "strict" can only import what is explicitly listed.

Coding Convention

For exported classes:

• private _method() — only used within the class itself
• _method() (no private) — used by other code in the same file, but not outside the file
• method() (public) — used in other files

Non-exported classes have no naming convention; they are internal implementation details.

Commit Convention

Before committing, run npm run flint and fix errors.

Semantic commit messages: label(scope): description

Labels: fix, feat, chore, docs, test, devops

git checkout -b fix-39562
# ... make changes ...
git add <changed-files>
git commit -m "$(cat <<'EOF'
fix(proxy): handle SOCKS proxy authentication

Fixes: https://github.com/microsoft/playwright/issues/39562
EOF
)"
# **Never `git push` without an explicit instruction to push.**
git push origin fix-39562
gh pr create --repo microsoft/playwright --head username:fix-39562 \
  --title "fix(proxy): handle SOCKS proxy authentication" \
  --body "$(cat <<'EOF'
## Summary
- <describe the change very! briefly>

Fixes https://github.com/microsoft/playwright/issues/39562
EOF
)"

Never add Co-Authored-By agents in commit message. Never add "Generated with" in commit message. Never add test plan to PR description. Keep PR description short — a few bullet points at most. Branch naming for issue fixes: fix-<issue-number>

Never amend commits. Always create a new commit for follow-up changes, even when iterating on an open PR. Amending rewrites history and forces a force-push, losing the incremental review trail. Only amend if the user explicitly says so.

Never git push without an explicit instruction to push. Applies even when a PR is already open for the branch — additional commits are immediately visible to reviewers. Commit locally, report what was committed, and wait. Only push when the user's message contains "push", "upload", "create PR", "ship it", or equivalent.

Development Guides

Detailed guides for common development tasks:

• Architecture: Client, Server, and Dispatchers — package layout, protocol layer, ChannelOwner/SdkObject/Dispatcher base classes, DEPS rules, end-to-end RPC flow, object lifecycle
• Adding and Modifying APIs — 6-step process: define docs → implement client → define protocol → implement dispatcher → implement server → write tests
• MCP Tools and CLI Commands — defineTool()/defineTabTool(), tool capabilities, CLI declareCommand(), config options, testing with MCP fixtures
• Vendoring Dependencies — bundle architecture, esbuild setup, typed wrappers, adding deps to existing bundles

Source: CLAUDE.md