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Playwright test agents are LLM-driven execution loops that wrap Playwright's browser automation in a goal-oriented reasoning layer. Instead of executing pre-written scripts, an agent receives high-level intent ("complete checkout and verify the success modal"), inspects the page's accessibility tree, and chooses which Playwright tool to invoke next. The Model Context Protocol (MCP) is the standardized bridge that exposes Playwright capabilities to the LLM and returns structured page context back.

Playwright is the standard for modern browser automation in 2026. It provides superior execution speed, native auto-waiting, and deep browser context control. However, running any automation framework at enterprise scale exposes operational friction. When engineering teams move from local execution to continuous integration, they encounter a consistent set of playwright pain points that the framework's official documentation rarely surfaces clearly.

Native Playwright visual regression is free to start and expensive to scale. The cost shows up in CI, not on day one. Cross-OS rendering breaks pixel diffs: Windows, macOS, and Linux render fonts and spacing differently, so the same code produces different baselines on different machines. Component snapshots beat full-page captures: smaller scope means clearer failure signal, fewer timeouts, and less flake on asset-heavy pages.

Five diagnostic patterns. One decision tree. A senior practitioner's triage playbook for Playwright flakiness in 2026. Flakiness is architectural, not framework-borne: Almost every flake traces back to async state, locator drift, session pollution, environment variance, or AI-agent non-determinism — not to Playwright itself.