refactor(app): carve the tuning-display helpers out of app.js (R3a)

static/js/tuning-display.js (228 lines) — bodies VERBATIM. app.js 9,838 → 9,650.
A LEAF: imports nothing.

Tuning NAME resolution (Drop D / Eb Standard / raw-offset fallback), bass
detection, effective string count, and the target FREQUENCIES + note names the
tuner checks against. Pure functions over a small MIDI/note-name table; the 3
_TUNING_* tables are read nowhere else and move in.

NOT A SLICE — a node-level extract. The span 2309-2535 INTERLEAVES the functions
with the `window.*` / `window.feedBack.*` assignments that publish them, and one
of those is `window.feedBack = window.feedBack || {}` — the BUS BOOTSTRAP, not
tuning code at all. Every ExpressionStatement stays exactly where it was; only the
16 functions and 3 tables move. app.js re-exposes the imported bindings from the
same lines, so the public surface and its ordering are untouched (constitution II
names window.feedBack).

  app.js -> { plugin-loader, viz, diagnostics-export, dom, highway-colors,
              tuning-display }

HARNESSES — 4 broke, and 3 of them broke in the SAME informative way: they sliced
app.js from `function isBassArrangement(` UP TO the marker
`window.feedBack.parseRawTuningOffsets = parseRawTuningOffsets;` — an end-marker
that (correctly) stayed behind in app.js. The module is now nothing BUT the tuning
helpers, so there is no block to slice: they read it whole and strip `export ` so
the vm sandbox still evaluates it as a script.
  tuner_auto_open is SPLIT — its autoplay-gate test still reads app.js, so it keeps
  APP_JS and gains TUNING_JS. Retargeting its path wholesale (my first attempt)
  silently pointed the autoplay test at the wrong file.

VERIFIED BY DRIVING THE CONTRACT. A/B against origin/main in two browsers, through
the real window surface: displayTuningName -> "E Standard" / "Drop D" /
"Eb Standard", parseRawTuningOffsets('-2,0,0,0,0,0') -> [-2,0,0,0,0,0],
isBassArrangement, effectiveStringCount, displayTuningTargets, and
window.feedBack.displayTuningName / .songTuningContext — IDENTICAL on both, zero
console/page errors either side.

pytest 2396, node 1038/1038, ESLint 0, tailwind-fresh clean, Codex 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

static/app.js

@@ -24,6 +24,15 @@ import {
     hwcInitSettingsUI,
     initHighwayColors,
 } from './js/highway-colors.js';
+import {
+    displayTuningName,
+    displayTuningTargetDetails,
+    displayTuningTargets,
+    effectiveStringCount,
+    isBassArrangement,
+    parseRawTuningOffsets,
+    songTuningContext,
+} from './js/tuning-display.js';
 
 // Demo analytics — real impl set by demo.js; no-op in normal builds
 window.feedBackDemoTrack = window.feedBackDemoTrack ?? null;
@@ -2305,227 +2314,31 @@ function toggleAllFavoriteArtists(expand) {
     _toggleAllInTree('fav-tree', expand, _FAV_TREE_EXPAND_KEY);
 }
 
-// Display-only tuning label helpers — never mutate offsets or affect playback.
-function _looksLikeRawTuningOffsets(str) {
-    if (!str || typeof str !== 'string') return false;
-    const s = str.trim();
-    if (!s) return false;
-    if (/^-?\d+$/.test(s)) return true;
-    if (/^-?\d+(?: -?\d+)+$/.test(s)) return true;
-    if (/^-?\d+(?:,-?\d+)+$/.test(s)) return true;
-    if (/^-?\d+(-?\d+){2,}$/.test(s)) return true;
-    return false;
-}
 
-function _tuningNameFromOffsets(offsets) {
-    if (!offsets || !offsets.length) return '';
-    const standard = {
-        0: 'E Standard', '-1': 'Eb Standard', '-2': 'D Standard',
-        '-3': 'C# Standard', '-4': 'C Standard', '-5': 'B Standard',
-        '-6': 'Bb Standard', '-7': 'A Standard',
-        1: 'F Standard', 2: 'F# Standard',
-    };
-    // Uniform offsets across 4 (bass) / 5 / 6 strings name the same Standard;
-    // a 4-string bass [0,0,0,0] must read "E Standard", not "Custom Tuning".
-    if (offsets.length >= 4 && offsets.every((o) => o === offsets[0])) {
-        const name = standard[offsets[0]];
-        if (name) return name;
-    }
-    if (offsets.length >= 4 && offsets[0] === offsets[1] - 2
-            && offsets.slice(1).every((o) => o === offsets[1])) {
-        const noteNames = ['E', 'F', 'F#', 'G', 'Ab', 'A', 'Bb', 'B', 'C', 'C#', 'D', 'Eb'];
-        return 'Drop ' + noteNames[((offsets[0] % 12) + 12) % 12];
-    }
-    const named = {
-        '-2,0,0,0,0,0': 'Drop D',
-        '-4,-2,-2,-2,-2,-2': 'Drop C',
-        '-2,-2,0,0,0,0': 'Double Drop D',
-        '0,0,0,-1,0,0': 'Open G',
-        '-2,-2,0,0,-2,-2': 'Open D',
-        '-2,0,0,0,-2,0': 'DADGAD',
-        '0,2,2,1,0,0': 'Open E',
-        '-2,0,0,2,3,2': 'Open D (alt)',
-    };
-    if (offsets.length === 6) {
-        const key = offsets.join(',');
-        if (named[key]) return named[key];
-    }
-    return 'Custom Tuning';
-}
 
-function displayTuningName(value, offsets) {
-    // Explicit offsets win — always name them.
-    if (Array.isArray(offsets) && offsets.length > 0) {
-        return _tuningNameFromOffsets(offsets);
-    }
-    if (value && typeof value === 'string') {
-        const trimmed = value.trim();
-        if (!trimmed || trimmed === 'Unknown') return '';
-        if (!_looksLikeRawTuningOffsets(trimmed)) {
-            return trimmed;
-        }
-        // A raw offset string (now served by the API) — parse and name it so a
-        // known tuning like "-1 -1 -1 -1 -1 -1" reads "Eb Standard" rather than
-        // collapsing to "Custom Tuning".
-        const parsed = (typeof parseRawTuningOffsets === 'function')
-            ? parseRawTuningOffsets(trimmed) : null;
-        if (parsed && parsed.length) return _tuningNameFromOffsets(parsed);
-        return 'Custom Tuning';
-    }
-    return '';
-}
 
 window.displayTuningName = displayTuningName;
 window.feedBack = window.feedBack || {};
 window.slopsmith = window.feedBack;
 window.feedBack.displayTuningName = displayTuningName;
 
-function isBassArrangement(context) {
-    const ctx = context && typeof context === 'object' ? context : {};
-    if (typeof ctx.isBass === 'boolean') return ctx.isBass;
-    const label = ((ctx.arrangement || '') + ' ' + (ctx.arrangement_smart_name || '')).toLowerCase();
-    if (/\bbass\b/.test(label)) return true;
-    if (/\b(lead|rhythm|combo|guitar)\b/.test(label)) return false;
-    return false;
-}
 
-function effectiveStringCount(offsets, context) {
-    if (!Array.isArray(offsets) || !offsets.length) return 0;
-    const ctx = context && typeof context === 'object' ? context : {};
-    const isBass = isBassArrangement(ctx);
-    let sc = ctx.stringCount > 0 ? Number(ctx.stringCount) : 0;
-    if (!isBass) {
-        if (sc > 0 && sc <= 5 && offsets.length >= 6) sc = 6;
-        if (!sc) sc = offsets.length >= 6 ? offsets.length : 6;
-    } else if (!sc) {
-        sc = offsets.length >= 5 ? offsets.length : 4;
-    }
-    return Math.min(sc, offsets.length);
-}
 
-function songTuningContext(songInfo) {
-    if (!songInfo || typeof songInfo !== 'object') return {};
-    return {
-        stringCount: songInfo.stringCount,
-        arrangement: songInfo.arrangement,
-        arrangement_smart_name: songInfo.arrangement_smart_name,
-    };
-}
 
 window.feedBack.isBassArrangement = isBassArrangement;
 window.feedBack.effectiveStringCount = effectiveStringCount;
 window.feedBack.songTuningContext = songTuningContext;
 
-// Open-string target notes (display only) — mirrors plugins/tuner/utils/tuning-utils.js.
-const _TUNING_BASE_MIDI = {
-    4: [28, 33, 38, 43],
-    5: [23, 28, 33, 38, 43],
-    6: [40, 45, 50, 55, 59, 64],
-    7: [35, 40, 45, 50, 55, 59, 64],
-    8: [30, 35, 40, 45, 50, 55, 59, 64],
-};
-const _TUNING_NOTE_SHARP = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B'];
-const _TUNING_NOTE_FLAT = ['C', 'Db', 'D', 'Eb', 'E', 'F', 'Gb', 'G', 'Ab', 'A', 'Bb', 'B'];
 
-function _tuningMidiToFreq(m) {
-    return Math.pow(2, (m - 69) / 12) * 440;
-}
 
-function _tuningOffsetsToFreqs(offsets, isBass) {
-    const len = offsets.length;
-    let base;
-    if (len === 4 || len === 5) {
-        base = isBass ? _TUNING_BASE_MIDI[len] : _TUNING_BASE_MIDI[6];
-    } else {
-        base = _TUNING_BASE_MIDI[len] || _TUNING_BASE_MIDI[6];
-    }
-    return offsets.map((offset, i) => {
-        const root = i < base.length ? base[i] : base[base.length - 1];
-        return _tuningMidiToFreq(root + offset);
-    });
-}
 
-function _noteNameFromFreq(freq, useFlats) {
-    const midi = 69 + 12 * Math.log2(freq / 440);
-    const rounded = Math.round(midi);
-    const names = useFlats ? _TUNING_NOTE_FLAT : _TUNING_NOTE_SHARP;
-    return names[((rounded % 12) + 12) % 12];
-}
 
-function _octaveNoteFromFreq(freq, useFlats) {
-    const midi = 69 + 12 * Math.log2(freq / 440);
-    const rounded = Math.round(midi);
-    const octave = Math.floor(rounded / 12) - 1;
-    return _noteNameFromFreq(freq, useFlats) + octave;
-}
 
-function _stringOrdinalLabel(n) {
-    const v = n % 100;
-    if (v >= 11 && v <= 13) return n + 'th';
-    const suffix = { 1: 'st', 2: 'nd', 3: 'rd' }[n % 10] || 'th';
-    return n + suffix;
-}
 
-function _tuningTargetFreqs(offsets, context) {
-    if (!Array.isArray(offsets) || !offsets.length) return [];
-    const ctx = context && typeof context === 'object' ? context : {};
-    const stringCount = effectiveStringCount(offsets, ctx);
-    const trimmed = offsets.slice(0, stringCount);
-    if (!trimmed.length) return [];
-    const isBass = isBassArrangement(ctx);
-    try {
-        return _tuningOffsetsToFreqs(trimmed, isBass);
-    } catch (_) {
-        return [];
-    }
-}
 
-// Flat vs sharp spelling. A caller that knows the preference can pass
-// ctx.useFlats; otherwise we infer from a flat-keyed tuning name. The v3
-// card/HUD pass "Custom Tuning" (raw offsets carry no key), so those default
-// to sharps unless an explicit useFlats is supplied.
-function _resolveTargetUseFlats(ctx) {
-    if (typeof ctx.useFlats === 'boolean') return ctx.useFlats;
-    return typeof ctx.tuningName === 'string' && /\b[A-G]b\b/.test(ctx.tuningName);
-}
 
-function displayTuningTargetDetails(offsets, context) {
-    const ctx = context && typeof context === 'object' ? context : {};
-    const useFlats = _resolveTargetUseFlats(ctx);
-    const freqs = _tuningTargetFreqs(offsets, ctx);
-    return freqs.map((f, i) => {
-        const stringNumber = freqs.length - i;
-        const note = _noteNameFromFreq(f, useFlats);
-        const octaveNote = _octaveNoteFromFreq(f, useFlats);
-        return {
-            stringNumber,
-            note,
-            octaveNote,
-            title: _stringOrdinalLabel(stringNumber) + ' string: ' + octaveNote,
-        };
-    });
-}
 
-function displayTuningTargets(offsets, context) {
-    const ctx = context && typeof context === 'object' ? context : {};
-    const useFlats = _resolveTargetUseFlats(ctx);
-    const freqs = _tuningTargetFreqs(offsets, ctx);
-    if (!freqs.length) return '';
-    return freqs.map((f) => _noteNameFromFreq(f, useFlats)).join(' ');
-}
 
-function parseRawTuningOffsets(value) {
-    if (Array.isArray(value) && value.length) return value;
-    if (!value || typeof value !== 'string') return null;
-    const s = value.trim();
-    if (/^-?\d+(?: -?\d+)+$/.test(s)) {
-        return s.split(/\s+/).map((n) => Number(n));
-    }
-    if (/^-?\d+(?:,-?\d+)+$/.test(s)) {
-        return s.split(',').map((n) => Number(n));
-    }
-    return null;
-}
 
 window.displayTuningTargets = displayTuningTargets;
 window.displayTuningTargetDetails = displayTuningTargetDetails;

static/js/tuning-display.js

@@ -0,0 +1,228 @@
+// Tuning display — naming, string counts, and target frequencies.
+//
+// Carved verbatim out of static/app.js (R3a). A LEAF module: imports nothing.
+//
+// Turns raw per-string semitone offsets into things a human reads: a tuning NAME
+// ("Drop D", "Eb Standard", or a raw-offsets fallback), whether an arrangement is
+// bass, its effective string count, and the target FREQUENCIES + note names the
+// tuner checks against. Pure functions over a small MIDI/note-name table.
+//
+// The window / window.feedBack assignments for these stay in app.js — they are the
+// public contract (constitution II names window.feedBack), and app.js re-exposes
+// the imported bindings from exactly where it always did, so nothing about the
+// surface or its ordering changes.
+
+// Display-only tuning label helpers — never mutate offsets or affect playback.
+function _looksLikeRawTuningOffsets(str) {
+    if (!str || typeof str !== 'string') return false;
+    const s = str.trim();
+    if (!s) return false;
+    if (/^-?\d+$/.test(s)) return true;
+    if (/^-?\d+(?: -?\d+)+$/.test(s)) return true;
+    if (/^-?\d+(?:,-?\d+)+$/.test(s)) return true;
+    if (/^-?\d+(-?\d+){2,}$/.test(s)) return true;
+    return false;
+}
+
+function _tuningNameFromOffsets(offsets) {
+    if (!offsets || !offsets.length) return '';
+    const standard = {
+        0: 'E Standard', '-1': 'Eb Standard', '-2': 'D Standard',
+        '-3': 'C# Standard', '-4': 'C Standard', '-5': 'B Standard',
+        '-6': 'Bb Standard', '-7': 'A Standard',
+        1: 'F Standard', 2: 'F# Standard',
+    };
+    // Uniform offsets across 4 (bass) / 5 / 6 strings name the same Standard;
+    // a 4-string bass [0,0,0,0] must read "E Standard", not "Custom Tuning".
+    if (offsets.length >= 4 && offsets.every((o) => o === offsets[0])) {
+        const name = standard[offsets[0]];
+        if (name) return name;
+    }
+    if (offsets.length >= 4 && offsets[0] === offsets[1] - 2
+            && offsets.slice(1).every((o) => o === offsets[1])) {
+        const noteNames = ['E', 'F', 'F#', 'G', 'Ab', 'A', 'Bb', 'B', 'C', 'C#', 'D', 'Eb'];
+        return 'Drop ' + noteNames[((offsets[0] % 12) + 12) % 12];
+    }
+    const named = {
+        '-2,0,0,0,0,0': 'Drop D',
+        '-4,-2,-2,-2,-2,-2': 'Drop C',
+        '-2,-2,0,0,0,0': 'Double Drop D',
+        '0,0,0,-1,0,0': 'Open G',
+        '-2,-2,0,0,-2,-2': 'Open D',
+        '-2,0,0,0,-2,0': 'DADGAD',
+        '0,2,2,1,0,0': 'Open E',
+        '-2,0,0,2,3,2': 'Open D (alt)',
+    };
+    if (offsets.length === 6) {
+        const key = offsets.join(',');
+        if (named[key]) return named[key];
+    }
+    return 'Custom Tuning';
+}
+
+export function displayTuningName(value, offsets) {
+    // Explicit offsets win — always name them.
+    if (Array.isArray(offsets) && offsets.length > 0) {
+        return _tuningNameFromOffsets(offsets);
+    }
+    if (value && typeof value === 'string') {
+        const trimmed = value.trim();
+        if (!trimmed || trimmed === 'Unknown') return '';
+        if (!_looksLikeRawTuningOffsets(trimmed)) {
+            return trimmed;
+        }
+        // A raw offset string (now served by the API) — parse and name it so a
+        // known tuning like "-1 -1 -1 -1 -1 -1" reads "Eb Standard" rather than
+        // collapsing to "Custom Tuning".
+        const parsed = (typeof parseRawTuningOffsets === 'function')
+            ? parseRawTuningOffsets(trimmed) : null;
+        if (parsed && parsed.length) return _tuningNameFromOffsets(parsed);
+        return 'Custom Tuning';
+    }
+    return '';
+}
+
+export function isBassArrangement(context) {
+    const ctx = context && typeof context === 'object' ? context : {};
+    if (typeof ctx.isBass === 'boolean') return ctx.isBass;
+    const label = ((ctx.arrangement || '') + ' ' + (ctx.arrangement_smart_name || '')).toLowerCase();
+    if (/\bbass\b/.test(label)) return true;
+    if (/\b(lead|rhythm|combo|guitar)\b/.test(label)) return false;
+    return false;
+}
+
+export function effectiveStringCount(offsets, context) {
+    if (!Array.isArray(offsets) || !offsets.length) return 0;
+    const ctx = context && typeof context === 'object' ? context : {};
+    const isBass = isBassArrangement(ctx);
+    let sc = ctx.stringCount > 0 ? Number(ctx.stringCount) : 0;
+    if (!isBass) {
+        if (sc > 0 && sc <= 5 && offsets.length >= 6) sc = 6;
+        if (!sc) sc = offsets.length >= 6 ? offsets.length : 6;
+    } else if (!sc) {
+        sc = offsets.length >= 5 ? offsets.length : 4;
+    }
+    return Math.min(sc, offsets.length);
+}
+
+export function songTuningContext(songInfo) {
+    if (!songInfo || typeof songInfo !== 'object') return {};
+    return {
+        stringCount: songInfo.stringCount,
+        arrangement: songInfo.arrangement,
+        arrangement_smart_name: songInfo.arrangement_smart_name,
+    };
+}
+
+// Open-string target notes (display only) — mirrors plugins/tuner/utils/tuning-utils.js.
+const _TUNING_BASE_MIDI = {
+    4: [28, 33, 38, 43],
+    5: [23, 28, 33, 38, 43],
+    6: [40, 45, 50, 55, 59, 64],
+    7: [35, 40, 45, 50, 55, 59, 64],
+    8: [30, 35, 40, 45, 50, 55, 59, 64],
+};
+
+const _TUNING_NOTE_SHARP = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B'];
+
+const _TUNING_NOTE_FLAT = ['C', 'Db', 'D', 'Eb', 'E', 'F', 'Gb', 'G', 'Ab', 'A', 'Bb', 'B'];
+
+function _tuningMidiToFreq(m) {
+    return Math.pow(2, (m - 69) / 12) * 440;
+}
+
+function _tuningOffsetsToFreqs(offsets, isBass) {
+    const len = offsets.length;
+    let base;
+    if (len === 4 || len === 5) {
+        base = isBass ? _TUNING_BASE_MIDI[len] : _TUNING_BASE_MIDI[6];
+    } else {
+        base = _TUNING_BASE_MIDI[len] || _TUNING_BASE_MIDI[6];
+    }
+    return offsets.map((offset, i) => {
+        const root = i < base.length ? base[i] : base[base.length - 1];
+        return _tuningMidiToFreq(root + offset);
+    });
+}
+
+function _noteNameFromFreq(freq, useFlats) {
+    const midi = 69 + 12 * Math.log2(freq / 440);
+    const rounded = Math.round(midi);
+    const names = useFlats ? _TUNING_NOTE_FLAT : _TUNING_NOTE_SHARP;
+    return names[((rounded % 12) + 12) % 12];
+}
+
+function _octaveNoteFromFreq(freq, useFlats) {
+    const midi = 69 + 12 * Math.log2(freq / 440);
+    const rounded = Math.round(midi);
+    const octave = Math.floor(rounded / 12) - 1;
+    return _noteNameFromFreq(freq, useFlats) + octave;
+}
+
+function _stringOrdinalLabel(n) {
+    const v = n % 100;
+    if (v >= 11 && v <= 13) return n + 'th';
+    const suffix = { 1: 'st', 2: 'nd', 3: 'rd' }[n % 10] || 'th';
+    return n + suffix;
+}
+
+function _tuningTargetFreqs(offsets, context) {
+    if (!Array.isArray(offsets) || !offsets.length) return [];
+    const ctx = context && typeof context === 'object' ? context : {};
+    const stringCount = effectiveStringCount(offsets, ctx);
+    const trimmed = offsets.slice(0, stringCount);
+    if (!trimmed.length) return [];
+    const isBass = isBassArrangement(ctx);
+    try {
+        return _tuningOffsetsToFreqs(trimmed, isBass);
+    } catch (_) {
+        return [];
+    }
+}
+
+// Flat vs sharp spelling. A caller that knows the preference can pass
+// ctx.useFlats; otherwise we infer from a flat-keyed tuning name. The v3
+// card/HUD pass "Custom Tuning" (raw offsets carry no key), so those default
+// to sharps unless an explicit useFlats is supplied.
+function _resolveTargetUseFlats(ctx) {
+    if (typeof ctx.useFlats === 'boolean') return ctx.useFlats;
+    return typeof ctx.tuningName === 'string' && /\b[A-G]b\b/.test(ctx.tuningName);
+}
+
+export function displayTuningTargetDetails(offsets, context) {
+    const ctx = context && typeof context === 'object' ? context : {};
+    const useFlats = _resolveTargetUseFlats(ctx);
+    const freqs = _tuningTargetFreqs(offsets, ctx);
+    return freqs.map((f, i) => {
+        const stringNumber = freqs.length - i;
+        const note = _noteNameFromFreq(f, useFlats);
+        const octaveNote = _octaveNoteFromFreq(f, useFlats);
+        return {
+            stringNumber,
+            note,
+            octaveNote,
+            title: _stringOrdinalLabel(stringNumber) + ' string: ' + octaveNote,
+        };
+    });
+}
+
+export function displayTuningTargets(offsets, context) {
+    const ctx = context && typeof context === 'object' ? context : {};
+    const useFlats = _resolveTargetUseFlats(ctx);
+    const freqs = _tuningTargetFreqs(offsets, ctx);
+    if (!freqs.length) return '';
+    return freqs.map((f) => _noteNameFromFreq(f, useFlats)).join(' ');
+}
+
+export function parseRawTuningOffsets(value) {
+    if (Array.isArray(value) && value.length) return value;
+    if (!value || typeof value !== 'string') return null;
+    const s = value.trim();
+    if (/^-?\d+(?: -?\d+)+$/.test(s)) {
+        return s.split(/\s+/).map((n) => Number(n));
+    }
+    if (/^-?\d+(?:,-?\d+)+$/.test(s)) {
+        return s.split(',').map((n) => Number(n));
+    }
+    return null;
+}

tests/js/tuner_auto_open.test.js

@@ -7,20 +7,23 @@ const path = require('node:path');
 const vm = require('node:vm');
 
 const APP_JS = path.join(__dirname, '..', '..', 'static', 'app.js');
+// The tuning-display helpers were carved out of app.js into their own module (R3a);
+// the autoplay-gate test below still reads app.js.
+const TUNING_JS = path.join(__dirname, '..', '..', 'static', 'js', 'tuning-display.js');
 const TUNER_SCREEN_JS = path.join(__dirname, '..', '..', 'plugins', 'tuner', 'screen.js');
 const TUNING_UTILS_JS = path.join(__dirname, '..', '..', 'plugins', 'tuner', 'utils', 'tuning-utils.js');
 const TUNER_UI_JS = path.join(__dirname, '..', '..', 'plugins', 'tuner', 'utils', 'ui.js');
 
 function loadTuningHelpers() {
-    const src = fs.readFileSync(APP_JS, 'utf8');
-    const start = src.indexOf('function isBassArrangement(');
-    const endMarker = 'window.feedBack.parseRawTuningOffsets = parseRawTuningOffsets;';
-    const end = src.indexOf(endMarker);
-    if (start === -1 || end === -1) throw new Error('tuning helper block not found in app.js');
+    const src = fs.readFileSync(TUNING_JS, 'utf8');
+    // The module is nothing BUT the tuning helpers now, so there is no block to
+    // slice out — take it whole. `export` is stripped so the vm sandbox can still
+    // evaluate it as a plain script (the window.* contract lives in app.js).
+    const body = src.replace(/^export /gm, '');
     const sandbox = { window: { feedBack: {} }, exports: {} };
     vm.createContext(sandbox);
     vm.runInContext(
-        src.slice(start, end + endMarker.length),
+        body,
         sandbox
     );
     return sandbox.window.feedBack;

tests/js/tuning_display.test.js

@@ -6,7 +6,8 @@ const fs = require('node:fs');
 const path = require('node:path');
 const vm = require('node:vm');
 
-const APP_JS = path.join(__dirname, '..', '..', 'static', 'app.js');
+// The tuning-display helpers were carved out of app.js into their own module (R3a).
+const APP_JS = path.join(__dirname, '..', '..', 'static', 'js', 'tuning-display.js');
 const HIGHWAY_JS = path.join(__dirname, '..', '..', 'static', 'highway.js');
 const V3_HTML = path.join(__dirname, '..', '..', 'static', 'v3', 'index.html');
 

tests/js/tuning_targets.test.js

@@ -6,7 +6,8 @@ const fs = require('node:fs');
 const path = require('node:path');
 const vm = require('node:vm');
 
-const APP_JS = path.join(__dirname, '..', '..', 'static', 'app.js');
+// The tuning-display helpers were carved out of app.js into their own module (R3a).
+const APP_JS = path.join(__dirname, '..', '..', 'static', 'js', 'tuning-display.js');
 const HIGHWAY_JS = path.join(__dirname, '..', '..', 'static', 'highway.js');
 const TUNER_UI_JS = path.join(__dirname, '..', '..', 'plugins', 'tuner', 'utils', 'ui.js');
 const TUNER_SCREEN_JS = path.join(__dirname, '..', '..', 'plugins', 'tuner', 'screen.js');
@@ -14,14 +15,14 @@ const V3_HTML = path.join(__dirname, '..', '..', 'static', 'v3', 'index.html');
 
 function loadTuningHelpers() {
     const src = fs.readFileSync(APP_JS, 'utf8');
-    const start = src.indexOf('function isBassArrangement(');
-    const endMarker = 'window.feedBack.parseRawTuningOffsets = parseRawTuningOffsets;';
-    const end = src.indexOf(endMarker);
-    if (start === -1 || end === -1) throw new Error('tuning helper block not found in app.js');
+    // The module is nothing BUT the tuning helpers now, so there is no block to
+    // slice out — take it whole. `export` is stripped so the vm sandbox can still
+    // evaluate it as a plain script (the window.* contract lives in app.js).
+    const body = src.replace(/^export /gm, '');
     const sandbox = { window: { feedBack: {} }, exports: {} };
     vm.createContext(sandbox);
     vm.runInContext(
-        src.slice(start, end + endMarker.length) + '\n'
+        body + '\n'
         + 'exports.displayTuningTargets = displayTuningTargets;\n'
         + 'exports.displayTuningTargetDetails = displayTuningTargetDetails;\n'
         + 'exports.isBassArrangement = isBassArrangement;\n'

tests/js/v3_songs_tuning.test.js

@@ -7,7 +7,8 @@ const path = require('node:path');
 const vm = require('node:vm');
 
 const SONGS_JS = path.join(__dirname, '..', '..', 'static', 'v3', 'songs.js');
-const APP_JS = path.join(__dirname, '..', '..', 'static', 'app.js');
+// The tuning-display helpers were carved out of app.js into their own module (R3a).
+const APP_JS = path.join(__dirname, '..', '..', 'static', 'js', 'tuning-display.js');
 
 function extractBlock(src, startMarker) {
     const start = src.indexOf(startMarker);
@@ -27,14 +28,14 @@ function extractBlock(src, startMarker) {
 
 function loadTuningHelpers() {
     const src = fs.readFileSync(APP_JS, 'utf8');
-    const start = src.indexOf('function _looksLikeRawTuningOffsets(');
-    const endMarker = 'window.feedBack.parseRawTuningOffsets = parseRawTuningOffsets;';
-    const end = src.indexOf(endMarker);
-    if (start === -1 || end === -1) throw new Error('tuning helpers not found');
+    // The module is nothing BUT the tuning helpers now, so there is no block to
+    // slice out — take it whole. `export` is stripped so the vm sandbox can still
+    // evaluate it as a plain script (the window.* contract lives in app.js).
+    const body = src.replace(/^export /gm, '');
     const sandbox = { window: { feedBack: {} }, exports: {} };
     vm.createContext(sandbox);
     vm.runInContext(
-        src.slice(start, end + endMarker.length) + '\n'
+        body + '\n'
         + 'exports.displayTuningName = displayTuningName;\n'
         + 'exports.displayTuningTargets = displayTuningTargets;\n'
         + 'exports.parseRawTuningOffsets = parseRawTuningOffsets;',