From mock-only-works to real-world-works: 48 hours of reCAPTCHA debugging

An open-source QA MCP server spent 48 hours debugging a reCAPTCHA solver before it worked on Google’s live demo.

The solver passed unit tests and a mock fixture, but failed in reality because the iframe included header and footer space the grid math ignored.

The fix was to stop estimating tile positions and instead use each tile’s actual DOM bounding box.

The case shows how test-only success can hide layout and selector bugs, and why live dogfooding matters for browser automation tools.