Build-an-X workflow that produces a test-case matrix from a **live, undocumented feature** - running app at a URL, screen recording, screenshot, or verbal brief - by combining structured exploration (Playwright trace / DevTools / accessibility tree) with the four canonical heuristic test-design models bundled in references/ (Bach's HTSM / SFDPOT product elements, Whittaker's How-to-Break-Software attacks, Bolton's FEW HICCUPPS consistency oracles, ISO/IEC 25010 quality characteristics). Output is a structured case matrix, not an exploratory session charter. Use when there is no story, no AC, and no documentation - only a live feature - or as the heuristic reference layer for zero-documentation test design.