Moves 12 pure-function / compile-time-constant exports from the screen.js
IIFE into a new src/utils.js ES module:
Color utils: _h3dHexToInt, _clampByteI, _darkenInt, _lightenInt
String-count: resolveStringCount
Tuning/pitch: _NOTE_NAMES_SHARP, _BASE_OPEN_MIDI_BASS4/5, _BASE_OPEN_MIDI_GUITAR6/7/8,
_baseOpenStringMidis, _midiToPitchLabel, _openStringPitchLabelsForTuning
Splitscreen: _ssActive, _ssIsCanvasFocused
Free-identifier audit: all clean. resolveStringCount uses MAX_RENDER_STRINGS
and NSTR — copied as compile-time constants (both = 6) matching IIFE values.
_ssActive/_ssIsCanvasFocused read window.feedBackSplitscreen live per call.
Survey discrepancy declared: the 12 functions span two non-contiguous regions
in current screen.js (lines 741–882 and 1490–1503) rather than the plan's
original 1703–2193 range; function list from the plan is exact.
New test file highway_3d_utils.test.js: 19 class-killer tests.
Mutation-verified (3-char shorthand removal → RED, original → GREEN).
Panel-controls sandbox: 16 stubs added for the new imports.
Suite: node --test tests/js/highway_3d*.test.js plugins/highway_3d/tests/*.test.js
188→207/207 pass.
Plugin: 3.38.0 → 3.39.0
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014uZ169yfoFYArXz962g7KW
