playwright

A set of guidelines for writing Playwright end-to-end tests, which check a website by using it like a user.

In plain words
What is it for?
It helps structure tests for navigation, localized pages, forms, third-party requests, authentication, and unexpected errors.
Why use it?
It reduces brittle browser tests by encouraging accessible selectors, deterministic test data, and checks of visible results.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/transloadit/node-sdk/playwright
Clone the repo
git clone --depth 1 https://github.com/transloadit/node-sdk
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 300 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00300
Opus 5 $0.00000 $0.00150
Sonnet 5 $0.00000 $0.00060
Haiku 4.5 $0.00000 $0.00030

Measured yesterday against content hash 562806840602, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

playwright scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.ai/rules/playwright.mdc · 17 lines

What it actually says

  • Prefer user-centric locators: getByRole/getByText with accessible names; avoid page.locator('body'), innerText(), or raw CSS unless there is no accessible alternative.
  • Treat data-* attributes as implementation details in browser tests unless they are the only stable contract available. If UI needs testing via state such as notifications, prefer adding or using an accessible role/name/state contract over asserting hidden implementation attributes.
  • Make positive assertions on expected UI/text instead of looping over regexes to assert absence.
  • Keep tests simple: no control-flow loops or extra variables for straightforward assertions.
  • For localized route work, cover page chrome as well as body content: navbar/mobile nav, search labels, subnav, post metadata/bylines, dynamic cards, html lang, canonical, and hreflang.
  • Navigate with relative URLs (page.goto('/path')) by setting baseURL in playwright.config.ts; avoid stringing environment URLs in tests.
  • Stub or mock external/third‑party requests (Intercom, Sentry, etc.) and any auth/login endpoints to keep tests deterministic; return minimal valid JSON when the app expects data.
  • Each unexpected error should surface and fail the test.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 17 lines · 0 tokens per session scan A 562806840602

Subscribe to this mod's changes

playwright is a cursor rule published in the GitHub repository transloadit/node-sdk (73 stars, last pushed 2d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 300 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.