Playwright or Stagehand v4? Choose by the job
Playwright remains the stronger default for repeatable product tests; Stagehand v4 is useful when an agent must navigate changing third-party pages.
Can Stagehand v4 replace Playwright? The useful answer is task-dependent. Playwright is a mature test framework with assertions and support for Chromium, Firefox, and WebKit. Stagehand v4 provides browser-agent methods such as act, observe, and extract, plus self-healing actions for changing interfaces.
Neither choice makes a workflow infallible. “100% identical every time” is a requirement to test for, not a guarantee from any tool. Stagehand can recover from some page changes, but its behavior still needs validation, and AI-assisted steps may involve model cost.
Use Playwright for product regression
When you control the application, write deterministic tests around known user flows, assertions, and fixtures. Playwright is the better fit for deployment gates and cross-browser checks involving Firefox or WebKit. It can run without an LLM call for every browser action, though browsers and CI still have operating costs.
Use Stagehand for changing external pages
When the target is a third-party site, an agent may need to find controls or extract data despite layout changes. Stagehand v4 offers natural-language actions and structured extraction for that work. It can also help with repetitive upload flows, provided each final submission is checked and the target platform permits automation.
Keep a clear boundary between the two
A practical setup uses Playwright for your own release checks and Stagehand for external research or assisted operations. Stagehand v4 is Chromium-only and does not accept a Playwright Page directly, so plan separate workflows rather than assuming the two SDKs can be dropped into the same session.