Left-handed players could already mirror the highway, but only via a buried
Settings toggle they had to find AFTER setup -- so a lefty went through the tour,
the tuner and calibration all right-handed first (community callout).
Add a "Handedness: Right / Left" row to the v3 instrument badge popover, alongside
Instrument / Strings / Tuning (all player-orientation choices). It writes the same
lefty preference -- highway.setLefty when a live highway exists (flips it
immediately + persists), else the 'lefty' localStorage key the highway reads on
init -- and keeps the Settings "Left-handed" checkbox in sync. The first-run
tour's "Choose your instrument" step, which runs before the tuner/audio-
calibration steps, now calls it out so lefties flip it up front.
Frontend-only, additive. Full core JS suite green (938). Tests:
tests/js/badges_handedness.test.js.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UR2Cr7GEu3yMY7SrfxH6c1
