Use when adding or changing a Playwright webtest in web/e2e/**/*.spec.ts for a calibration flow (XY/XZ/YZ, pressure advance, extrusion multiplier, input shaper, or any future flow), for coupon gcode generation, or for slicer preset import, or when a measurement-engine change needs a test that would actually catch it, before committing the change.
Use when adding or changing a Vitest unit test under web/tests/**, when reviewing unit tests, or when a code change needs a unit test that would actually catch a real bug, before committing the change.
Use when writing or revising the README, landing text, release announcements, or any outward-facing text meant to attract new users. Evidence-backed rules for converting a technical hobbyist audience.
Use when adding or changing anything in a coupon G-code generator (a new printed region, raster fill, perimeter, travel/retract logic, line widths, speeds, or layer plan) in web/src/engine/*/gcodeGenerator.ts, before committing the change.
Use when writing or changing any user-facing guidance text (tips, hints, warnings, step instructions, status messages) in the web app, before committing the change. Ensures critical constraints are actually seen and instructions survive skimming.