diff --git a/plugins/highway_3d/plugin.json b/plugins/highway_3d/plugin.json
index bc61390..5800bd9 100644
--- a/plugins/highway_3d/plugin.json
+++ b/plugins/highway_3d/plugin.json
@@ -1,7 +1,7 @@
 {
     "id": "highway_3d",
     "name": "3D Highway",
-    "version": "3.36.0",
+    "version": "3.37.0",
     "type": "visualization",
     "scriptType": "module",
     "bundled": true,
diff --git a/plugins/highway_3d/screen.js b/plugins/highway_3d/screen.js
index 8c2b5ae..2f77983 100644
--- a/plugins/highway_3d/screen.js
+++ b/plugins/highway_3d/screen.js
@@ -6,7 +6,7 @@
 // main player and per-panel in splitscreen without any architectural
 // changes.
 
-import { geoFretX, dZ, slideTrailEnd, camBaseDistU, camLowFretPullbackU, computeBPM, _makeGaussTex } from './src/geometry.js'; // h3d-carve-1
+import { geoFretX, dZ, slideTrailEnd, camBaseDistU, camLowFretPullbackU, computeBPM, _makeGaussTex, RENDER_ORDER_LAYER_STACK, RENDER_ORDER_LAYER_INDEX, RENDER_ORDER_AT_Z_ZERO, RENDER_ORDER_FAR_CLAMP, renderOrderForLayerAtZ, _noteKey, lowerBoundT, hwyFirstRelevantFrettedTime, geoFretMid } from './src/geometry.js'; // h3d-carve-1b
 
 (function () {
     'use strict';
@@ -971,58 +971,8 @@ import { geoFretX, dZ, slideTrailEnd, camBaseDistU, camLowFretPullbackU, compute
     /** Note travel speed. */
     const TS = 230 * K;
 
-    const RENDER_ORDER_LAYER_STACK = Object.freeze([
-        'CHORD_FILL',
-        'CHORD_STRUM_FILL',
-        'CHORD_STRUM_LINE',
-        'SUSTAIN_TRAIL',
-        'CHORD_FRAME',
-        'CHORD_EDGE_GLOW',
-        'CONNECTOR_LINE',
-        'FRET_COLUMN',
-        'ARP_CONNECTOR_LINE',
-        'NOTE_OUTLINE',
-        'NOTE_CORE',
-        'TECHNIQUE_MARKER',
-        'BOARD_STRING',
-        'BOARD_FRET_WIRE',
-        'NOTE_FRET_LABEL',
-        'ARP_NOTE_FRET_LABEL',
-        'CHORD_FRET_LABEL',
-    ]);
-    const RENDER_ORDER_LAYER_INDEX = Object.freeze(RENDER_ORDER_LAYER_STACK.reduce(
-        (indexByLayer, layerName, layerIndex) => {
-            indexByLayer[layerName] = layerIndex;
-            return indexByLayer;
-        },
-        Object.create(null)
-    ));
-
-    const RENDER_ORDER_AT_Z_ZERO = 700;
-    const RENDER_ORDER_FAR_CLAMP = 50;
-
-    /**
-     * Computes renderOrder from world depth plus a named layer.
-     * Closer objects receive larger values and paint over farther objects; the
-     * layer stack breaks ties at the same depth, keeping labels above note gems.
-     *
-     * The layer index is added as a sub-unit fraction (< 1) so the integer
-     * depth bucket STRICTLY dominates: a farther object can never outrank a
-     * nearer one merely because it sits on a higher layer. Adding the raw index
-     * (0..N-1) directly would let the ~N-wide layer span leak across depth
-     * buckets and re-introduce far-over-near bleed for notes within ~N draw
-     * units of each other. Fraction granularity (1/N ≈ 0.06) stays well above
-     * the 0.0001 intra-element sub-increments used at some call sites.
-     */
-    function renderOrderForLayerAtZ(worldZ, layerName) {
-        const layerIndex = RENDER_ORDER_LAYER_INDEX[layerName];
-        if (layerIndex === undefined) throw new Error(`Unknown 3D highway depth layer: ${layerName}`);
-        const depthRenderOrder = Math.max(
-            RENDER_ORDER_FAR_CLAMP,
-            Math.round(RENDER_ORDER_AT_Z_ZERO + worldZ / K)
-        );
-        return depthRenderOrder + layerIndex / RENDER_ORDER_LAYER_STACK.length;
-    }
+    // RENDER_ORDER_LAYER_STACK, RENDER_ORDER_LAYER_INDEX, RENDER_ORDER_AT_Z_ZERO,
+    // RENDER_ORDER_FAR_CLAMP, renderOrderForLayerAtZ — moved to src/geometry.js (h3d-carve-1b).
 
     /** Match `nextNoteByString` onset to this note (float + chart rounding; avoids ghost / glow flicker). */
     const NEXT_ON_STRING_T_EPS = 0.06;
@@ -1285,80 +1235,7 @@ import { geoFretX, dZ, slideTrailEnd, camBaseDistU, camLowFretPullbackU, compute
         return cadence.slice(i0, i1);
     }
 
-    // Fast integer key for (t, s) pairs — avoids per-frame string allocation in
-    // hot-path Set lookups. Encodes chart time in 0.1 ms steps (sufficient for
-    // chart-format note precision) combined with the string index.
-    // t range 0–600 s → 0–6,000,000; * 10 + s(0–7) = max 60,000,007 < 2^53 ✓.
-    // The |0 truncates to int32 but the outer multiply stays in float64, so the
-    // key is always a safe JS integer for songs ≤ 214,748 s (well above any song).
-    function _noteKey(t, s) { return ((t * 10000 + 0.5) | 0) * 10 + s; }
-
-    // Binary lower-bound: returns the first index i in arr where arr[i].t >= t.
-    // Assumes arr is sorted ascending by .t (bundle.notes / bundle.chords always are).
-    // Byte-identical to core's bundle.lowerBoundT — kept as a local because this
-    // plugin must run on downlevel hosts whose bundles don't carry the helper
-    // (it's called from ~30 sites incl. top-level helpers that don't receive a
-    // bundle). New code that already holds a bundle should prefer
-    // bundle.lowerBoundT / bundle.lowerBoundTime.
-    function lowerBoundT(arr, t) {
-        let lo = 0, hi = arr.length;
-        while (lo < hi) {
-            const mid = (lo + hi) >>> 1;
-            if (arr[mid].t < t) lo = mid + 1;
-            else hi = mid;
-        }
-        return lo;
-    }
-
-    /**
-     * Return the chart time of the first fretted event that can still affect
-     * the camera at `now`, or the next fretted onset after it.
-     *
-     * This is intentionally a one-time full-chart scan. It runs only when a
-     * new song/arrangement's arrays first arrive, allowing the camera to frame
-     * the opening phrase during a silent intro instead of waiting for that
-     * phrase to enter the live targeting window. Open strings do not define a
-     * horizontal fret target, and malformed/out-of-range strings are ignored.
-     *
-     * Events already inside the behind-window, plus older sustains that are
-     * still ringing at `now`, return `now` so bootstrap framing matches the
-     * ordinary live path. Future events return their onset time.
-     */
-    function hwyFirstRelevantFrettedTime(notes, chords, now, behind, stringCount) {
-        const nStrings = Number.isFinite(stringCount) ? Math.max(0, Math.floor(stringCount)) : 0;
-        const cameraFloor = now - Math.max(0, Number(behind) || 0);
-        let first = Infinity;
-
-        const validFretted = n => n
-            && n.f > 0
-            && Number.isInteger(n.s)
-            && n.s >= 0
-            && n.s < nStrings;
-        const consider = (eventTime, sustain) => {
-            const t = Number(eventTime);
-            if (!Number.isFinite(t)) return;
-            const sus = Number(sustain);
-            const end = t + (Number.isFinite(sus) && sus > 0 ? sus : 0);
-            if (t < cameraFloor && end < now) return;
-            const relevantTime = t <= now ? now : t;
-            if (relevantTime < first) first = relevantTime;
-        };
-
-        if (notes) {
-            for (const n of notes) {
-                if (validFretted(n)) consider(n.t, n.sus);
-            }
-        }
-        if (chords) {
-            for (const ch of chords) {
-                if (!ch || !ch.notes) continue;
-                for (const cn of ch.notes) {
-                    if (validFretted(cn)) consider(ch.t, cn.sus);
-                }
-            }
-        }
-        return Number.isFinite(first) ? first : null;
-    }
+    // _noteKey, lowerBoundT, hwyFirstRelevantFrettedTime — moved to src/geometry.js (h3d-carve-1b).
 
     // Last arrangement <anchor> at or before chart time `t` (sorted by .time).
     // Mirrors static/highway.js getAnchorAt — until t reaches the first anchor’s
@@ -1540,7 +1417,7 @@ import { geoFretX, dZ, slideTrailEnd, camBaseDistU, camLowFretPullbackU, compute
         _bgEmitChange('fretSpacing');
     };
 
-    const fretMid = f => (f <= 0 ? -2 * K : (fretX(f - 1) + fretX(f)) / 2);
+    const fretMid = f => geoFretMid(f, _h3dFretUniform); // h3d-carve-1b: delegator (1 beyond-subst)
     /** World-space width of fret column (wires f−1 .. f); used to scale row markers past ~12. */
     function fretColumnWorldW(f) {
         const fi = Math.round(Number(f));
diff --git a/plugins/highway_3d/src/geometry.js b/plugins/highway_3d/src/geometry.js
index 04492e7..5f71f76 100644
--- a/plugins/highway_3d/src/geometry.js
+++ b/plugins/highway_3d/src/geometry.js
@@ -107,6 +107,150 @@ export function computeBPM(beats, t) {
     return count > 0 && sum > 0 ? 60 / (sum / count) : 120;
 }
 
+// ── Render-order layer stack — h3d-carve-1b ───────────────────────────────────
+
+export const RENDER_ORDER_LAYER_STACK = Object.freeze([
+    'CHORD_FILL',
+    'CHORD_STRUM_FILL',
+    'CHORD_STRUM_LINE',
+    'SUSTAIN_TRAIL',
+    'CHORD_FRAME',
+    'CHORD_EDGE_GLOW',
+    'CONNECTOR_LINE',
+    'FRET_COLUMN',
+    'ARP_CONNECTOR_LINE',
+    'NOTE_OUTLINE',
+    'NOTE_CORE',
+    'TECHNIQUE_MARKER',
+    'BOARD_STRING',
+    'BOARD_FRET_WIRE',
+    'NOTE_FRET_LABEL',
+    'ARP_NOTE_FRET_LABEL',
+    'CHORD_FRET_LABEL',
+]);
+export const RENDER_ORDER_LAYER_INDEX = Object.freeze(RENDER_ORDER_LAYER_STACK.reduce(
+    (indexByLayer, layerName, layerIndex) => {
+        indexByLayer[layerName] = layerIndex;
+        return indexByLayer;
+    },
+    Object.create(null)
+));
+
+export const RENDER_ORDER_AT_Z_ZERO = 700;
+export const RENDER_ORDER_FAR_CLAMP = 50;
+
+/**
+ * Computes renderOrder from world depth plus a named layer.
+ * Closer objects receive larger values and paint over farther objects; the
+ * layer stack breaks ties at the same depth, keeping labels above note gems.
+ *
+ * The layer index is added as a sub-unit fraction (< 1) so the integer
+ * depth bucket STRICTLY dominates: a farther object can never outrank a
+ * nearer one merely because it sits on a higher layer. Adding the raw index
+ * (0..N-1) directly would let the ~N-wide layer span leak across depth
+ * buckets and re-introduce far-over-near bleed for notes within ~N draw
+ * units of each other. Fraction granularity (1/N ≈ 0.06) stays well above
+ * the 0.0001 intra-element sub-increments used at some call sites.
+ */
+export function renderOrderForLayerAtZ(worldZ, layerName) {
+    const layerIndex = RENDER_ORDER_LAYER_INDEX[layerName];
+    if (layerIndex === undefined) throw new Error(`Unknown 3D highway depth layer: ${layerName}`);
+    const depthRenderOrder = Math.max(
+        RENDER_ORDER_FAR_CLAMP,
+        Math.round(RENDER_ORDER_AT_Z_ZERO + worldZ / K)
+    );
+    return depthRenderOrder + layerIndex / RENDER_ORDER_LAYER_STACK.length;
+}
+
+// ── Note key and binary search — h3d-carve-1b ─────────────────────────────────
+
+// Fast integer key for (t, s) pairs — avoids per-frame string allocation in
+// hot-path Set lookups. Encodes chart time in 0.1 ms steps (sufficient for
+// chart-format note precision) combined with the string index.
+// t range 0–600 s → 0–6,000,000; * 10 + s(0–7) = max 60,000,007 < 2^53 ✓.
+// The |0 truncates to int32 but the outer multiply stays in float64, so the
+// key is always a safe JS integer for songs ≤ 214,748 s (well above any song).
+export function _noteKey(t, s) { return ((t * 10000 + 0.5) | 0) * 10 + s; }
+
+// Binary lower-bound: returns the first index i in arr where arr[i].t >= t.
+// Assumes arr is sorted ascending by .t (bundle.notes / bundle.chords always are).
+// Byte-identical to core's bundle.lowerBoundT — kept as a local because this
+// plugin must run on downlevel hosts whose bundles don't carry the helper
+// (it's called from ~30 sites incl. top-level helpers that don't receive a
+// bundle). New code that already holds a bundle should prefer
+// bundle.lowerBoundT / bundle.lowerBoundTime.
+export function lowerBoundT(arr, t) {
+    let lo = 0, hi = arr.length;
+    while (lo < hi) {
+        const mid = (lo + hi) >>> 1;
+        if (arr[mid].t < t) lo = mid + 1;
+        else hi = mid;
+    }
+    return lo;
+}
+
+/**
+ * Return the chart time of the first fretted event that can still affect
+ * the camera at `now`, or the next fretted onset after it.
+ *
+ * This is intentionally a one-time full-chart scan. It runs only when a
+ * new song/arrangement's arrays first arrive, allowing the camera to frame
+ * the opening phrase during a silent intro instead of waiting for that
+ * phrase to enter the live targeting window. Open strings do not define a
+ * horizontal fret target, and malformed/out-of-range strings are ignored.
+ *
+ * Events already inside the behind-window, plus older sustains that are
+ * still ringing at `now`, return `now` so bootstrap framing matches the
+ * ordinary live path. Future events return their onset time.
+ */
+export function hwyFirstRelevantFrettedTime(notes, chords, now, behind, stringCount) {
+    const nStrings = Number.isFinite(stringCount) ? Math.max(0, Math.floor(stringCount)) : 0;
+    const cameraFloor = now - Math.max(0, Number(behind) || 0);
+    let first = Infinity;
+
+    const validFretted = n => n
+        && n.f > 0
+        && Number.isInteger(n.s)
+        && n.s >= 0
+        && n.s < nStrings;
+    const consider = (eventTime, sustain) => {
+        const t = Number(eventTime);
+        if (!Number.isFinite(t)) return;
+        const sus = Number(sustain);
+        const end = t + (Number.isFinite(sus) && sus > 0 ? sus : 0);
+        if (t < cameraFloor && end < now) return;
+        const relevantTime = t <= now ? now : t;
+        if (relevantTime < first) first = relevantTime;
+    };
+
+    if (notes) {
+        for (const n of notes) {
+            if (validFretted(n)) consider(n.t, n.sus);
+        }
+    }
+    if (chords) {
+        for (const ch of chords) {
+            if (!ch || !ch.notes) continue;
+            for (const cn of ch.notes) {
+                if (validFretted(cn)) consider(ch.t, cn.sus);
+            }
+        }
+    }
+    return Number.isFinite(first) ? first : null;
+}
+
+// ── Fret mid — h3d-carve-1b ───────────────────────────────────────────────────
+
+/**
+ * World-space X of the midpoint of fret column f.
+ * f <= 0 → nut-side sentinel (−2K).
+ * screen.js keeps `const fretMid = f => geoFretMid(f, _h3dFretUniform);`
+ * so no call-site changes in screen.js.
+ * @param {number}  f       fret number
+ * @param {boolean} uniform true → uniform spacing; false → logarithmic
+ */
+export const geoFretMid = (f, uniform) => f <= 0 ? -2 * K : (geoFretX(f - 1, uniform) + geoFretX(f, uniform)) / 2;
+
 // ── Gaussian bloom texture ────────────────────────────────────────────────────
 
 // Build a horizontal gaussian DataTexture for the sustain-rail bloom effect.
diff --git a/tests/js/highway_3d_camera_bootstrap.test.js b/tests/js/highway_3d_camera_bootstrap.test.js
index bc12193..f68e0d2 100644
--- a/tests/js/highway_3d_camera_bootstrap.test.js
+++ b/tests/js/highway_3d_camera_bootstrap.test.js
@@ -13,6 +13,9 @@ const path = require('node:path');
 
 const SCREEN_JS = path.join(__dirname, '..', '..', 'plugins', 'highway_3d', 'screen.js');
 const src = fs.readFileSync(SCREEN_JS, 'utf8');
+// Since h3d-carve-1b, hwyFirstRelevantFrettedTime lives in geometry.js.
+const GEOMETRY_JS = path.join(__dirname, '..', '..', 'plugins', 'highway_3d', 'src', 'geometry.js');
+const geoSrc = fs.readFileSync(GEOMETRY_JS, 'utf8');
 
 function extractFn(source, name) {
     const start = source.indexOf('function ' + name);
@@ -36,7 +39,7 @@ function sourceBetween(startText, endText) {
 
 const hwyFirstRelevantFrettedTime = new Function(
     '"use strict";'
-    + extractFn(src, 'hwyFirstRelevantFrettedTime')
+    + extractFn(geoSrc, 'hwyFirstRelevantFrettedTime')
     + '\nreturn hwyFirstRelevantFrettedTime;',
 )();
 
diff --git a/tests/js/highway_3d_geometry.test.js b/tests/js/highway_3d_geometry.test.js
index 92a98c8..23947f1 100644
--- a/tests/js/highway_3d_geometry.test.js
+++ b/tests/js/highway_3d_geometry.test.js
@@ -99,6 +99,67 @@ test('camLowFretPullbackU is clamped to zero — high fret gives 0 not negative'
     assert.strictEqual(camLowFretPullbackU(10),  0, 'fret 10: clamped to 0, not -20');
 });
 
+// ── Cut 1b class-killers ───────────────────────────────────────────────────────
+
+test('RENDER_ORDER_LAYER_STACK has 17 layers with CHORD_FILL first and CHORD_FRET_LABEL last', async () => {
+    const { RENDER_ORDER_LAYER_STACK } = await import(GEOMETRY_JS);
+    assert.strictEqual(RENDER_ORDER_LAYER_STACK.length, 17, 'stack must have exactly 17 layers');
+    assert.strictEqual(RENDER_ORDER_LAYER_STACK[0], 'CHORD_FILL', 'first layer must be CHORD_FILL');
+    assert.strictEqual(RENDER_ORDER_LAYER_STACK[RENDER_ORDER_LAYER_STACK.length - 1], 'CHORD_FRET_LABEL', 'last layer must be CHORD_FRET_LABEL');
+});
+
+test('RENDER_ORDER_LAYER_INDEX maps CHORD_FILL to 0 and NOTE_CORE to 10', async () => {
+    // Mutation: wrong layer order → NOTE_CORE would not map to 10.
+    const { RENDER_ORDER_LAYER_INDEX } = await import(GEOMETRY_JS);
+    assert.strictEqual(RENDER_ORDER_LAYER_INDEX['CHORD_FILL'], 0, 'CHORD_FILL must be index 0 (bottom of stack)');
+    assert.strictEqual(RENDER_ORDER_LAYER_INDEX['NOTE_CORE'], 10, 'NOTE_CORE must be index 10');
+});
+
+test('renderOrderForLayerAtZ applies the far clamp — worldZ=-5 gives 50 not 33', async () => {
+    // Mutation: remove Math.max(RENDER_ORDER_FAR_CLAMP, ...) clamp.
+    // K=2.25/300=0.0075; Math.round(700+(-5)/0.0075)=Math.round(33.33)=33; max(50,33)=50.
+    // Without clamp: 33 + 0/17 ≈ 33. Test pins the clamped value.
+    const { renderOrderForLayerAtZ } = await import(GEOMETRY_JS);
+    assert.strictEqual(renderOrderForLayerAtZ(-5, 'CHORD_FILL'), 50, 'far objects must be clamped to RENDER_ORDER_FAR_CLAMP=50');
+});
+
+test('renderOrderForLayerAtZ throws for unknown layer names', async () => {
+    const { renderOrderForLayerAtZ } = await import(GEOMETRY_JS);
+    assert.throws(() => renderOrderForLayerAtZ(0, 'NONEXISTENT'), /Unknown 3D highway depth layer/);
+});
+
+test('_noteKey integer-truncates float times — _noteKey(1.5, 3) is 150003 not 150008', async () => {
+    // Mutation: drop |0 → (15000.5)*10+3 = 150008.
+    const { _noteKey } = await import(GEOMETRY_JS);
+    assert.strictEqual(_noteKey(1.5, 3), 150003, '|0 truncation must give 150003, not float-derived 150008');
+    assert.strictEqual(_noteKey(0, 0), 0);
+});
+
+test('lowerBoundT returns first index where arr[i].t >= t (strict lower bound)', async () => {
+    // Mutation: < → <= causes lowerBoundT([{t:1},{t:3},{t:5}], 3) → 2 instead of 1.
+    const { lowerBoundT } = await import(GEOMETRY_JS);
+    const arr = [{ t: 1 }, { t: 3 }, { t: 5 }];
+    assert.strictEqual(lowerBoundT(arr, 3), 1, 'strict lower-bound: first index where .t >= 3 is 1 (not 2)');
+    assert.strictEqual(lowerBoundT(arr, 0), 0, 'value before all: must return 0');
+    assert.strictEqual(lowerBoundT(arr, 6), 3, 'value after all: must return length');
+});
+
+test('hwyFirstRelevantFrettedTime returns null for empty/all-open input', async () => {
+    const { hwyFirstRelevantFrettedTime } = await import(GEOMETRY_JS);
+    assert.strictEqual(hwyFirstRelevantFrettedTime([], [], 0, 0.2, 6), null);
+});
+
+test('geoFretMid returns -2K sentinel for f<=0, positive for f=1', async () => {
+    // Mutation: drop f<=0 guard → geoFretMid(0, true) returns (0+0)/2=0, not -0.015.
+    const { geoFretMid } = await import(GEOMETRY_JS);
+    const K = 2.25 / 300;
+    assert.ok(Math.abs(geoFretMid(0, true) - (-2 * K)) < 1e-10, 'f=0 must return -2K sentinel (≈-0.015)');
+    assert.ok(geoFretMid(1, true) > 0, 'f=1 must return positive X');
+    // In uniform mode: geoFretX(0,true)=0, geoFretX(1,true)=step, so mid=step/2.
+    // geoFretMid(2,true) = (step+2step)/2 = 1.5step. Ratio 3 catches wrong f offset.
+    assert.ok(Math.abs(geoFretMid(2, true) / geoFretMid(1, true) - 3) < 1e-9, 'uniform mid(2)/mid(1) must equal 3');
+});
+
 test('_makeGaussTex peak alpha is 255 at the centre pixel', async () => {
     // Mutation: default sigma changed to 0 → (u-0.5)/0 = NaN chain → all Uint8Array writes
     // become 0 (TypedArray coerces NaN to 0). Test calls without explicit sigma so the
diff --git a/tests/js/highway_3d_panel_controls.test.js b/tests/js/highway_3d_panel_controls.test.js
index cc71427..26139f6 100644
--- a/tests/js/highway_3d_panel_controls.test.js
+++ b/tests/js/highway_3d_panel_controls.test.js
@@ -55,7 +55,7 @@ function loadHighway3dStatics() {
             },
         },
         // Geometry stubs — panel-controls test only reads factory statics;
-        // it never invokes the render path where these are called (h3d-carve-1).
+        // it never invokes the render path where these are called (h3d-carve-1b).
         geoFretX: (f, _uniform) => f * 0.1,
         dZ: dt => -dt,
         slideTrailEnd: () => null,
@@ -63,6 +63,15 @@ function loadHighway3dStatics() {
         camLowFretPullbackU: () => 0,
         computeBPM: () => 120,
         _makeGaussTex: () => ({}),
+        RENDER_ORDER_LAYER_STACK: Object.freeze([]),
+        RENDER_ORDER_LAYER_INDEX: Object.freeze(Object.create(null)),
+        RENDER_ORDER_AT_Z_ZERO: 700,
+        RENDER_ORDER_FAR_CLAMP: 50,
+        renderOrderForLayerAtZ: () => 0,
+        _noteKey: () => 0,
+        lowerBoundT: () => 0,
+        hwyFirstRelevantFrettedTime: () => null,
+        geoFretMid: (f, _uniform) => f * 0.1,
     };
     vm.createContext(sandbox);
     vm.runInContext(instrumented, sandbox, { filename: SCREEN_JS });
diff --git a/tests/js/highway_3d_render_order.test.js b/tests/js/highway_3d_render_order.test.js
index e3bbc23..ea2bb95 100644
--- a/tests/js/highway_3d_render_order.test.js
+++ b/tests/js/highway_3d_render_order.test.js
@@ -41,6 +41,9 @@ const fs = require('node:fs');
 const path = require('node:path');
 
 const SCREEN_JS = path.join(__dirname, '..', '..', 'plugins', 'highway_3d', 'screen.js');
+// Since h3d-carve-1b, RENDER_ORDER_* constants and renderOrderForLayerAtZ
+// live in geometry.js; screen.js imports them.
+const GEOMETRY_JS = path.join(__dirname, '..', '..', 'plugins', 'highway_3d', 'src', 'geometry.js');
 
 // ---------------------------------------------------------------------------
 // Helpers
@@ -53,9 +56,16 @@ function src() {
     return _src;
 }
 
-/** Parses the declared render-order layer stack from screen.js. */
+let _geo;
+/** Returns the cached geometry source (render-order constants + renderOrderForLayerAtZ). */
+function geo() {
+    if (!_geo) _geo = fs.readFileSync(GEOMETRY_JS, 'utf8');
+    return _geo;
+}
+
+/** Parses the declared render-order layer stack from geometry.js. */
 function layers() {
-    const match = src().match(/const\s+RENDER_ORDER_LAYER_STACK\s*=\s*Object\.freeze\(\s*\[([\s\S]*?)\]\s*\)/);
+    const match = geo().match(/const\s+RENDER_ORDER_LAYER_STACK\s*=\s*Object\.freeze\(\s*\[([\s\S]*?)\]\s*\)/);
     assert.ok(match, 'RENDER_ORDER_LAYER_STACK must be declared');
     return Array.from(match[1].matchAll(/'([^']+)'/g), m => m[1]);
 }
@@ -70,7 +80,7 @@ function layerIndex(name) {
 
 /** Reads the render-order base used for objects at z = 0. */
 function zZeroRenderOrder() {
-    const match = src().match(/const\s+RENDER_ORDER_AT_Z_ZERO\s*=\s*(-?\d+(?:\.\d+)?)\s*;/);
+    const match = geo().match(/const\s+RENDER_ORDER_AT_Z_ZERO\s*=\s*(-?\d+(?:\.\d+)?)\s*;/);
     assert.ok(match, 'RENDER_ORDER_AT_Z_ZERO must be declared');
     return Number(match[1]);
 }
@@ -301,14 +311,15 @@ test('chordFrameRenderOrder uses renderOrderForLayerAtZ(z, CHORD_FRAME)', () =>
         /const\s+chordFrameRenderOrder\s*=\s*renderOrderForLayerAtZ\(\s*z\s*,\s*'CHORD_FRAME'\s*\)\s*;/,
         'chordFrameRenderOrder must use renderOrderForLayerAtZ(z, CHORD_FRAME)',
     );
-    assert.match(src(), /const\s+RENDER_ORDER_LAYER_INDEX\s*=\s*Object\.freeze\(\s*RENDER_ORDER_LAYER_STACK\.reduce\(/);
-    assert.match(src(), /const\s+layerIndex\s*=\s*RENDER_ORDER_LAYER_INDEX\[layerName\]\s*;/);
-    assert.match(src(), /if\s*\(\s*layerIndex\s*===\s*undefined\s*\)\s*throw\s+new\s+Error\(`Unknown 3D highway depth layer: \$\{layerName\}`\)\s*;/);
-    assert.match(src(), /const\s+depthRenderOrder\s*=\s*Math\.max\(\s*RENDER_ORDER_FAR_CLAMP\s*,\s*Math\.round\(\s*RENDER_ORDER_AT_Z_ZERO\s*\+\s*worldZ\s*\/\s*K\s*\)\s*\)\s*;/);
+    // renderOrderForLayerAtZ implementation lives in geometry.js since h3d-carve-1b.
+    assert.match(geo(), /const\s+RENDER_ORDER_LAYER_INDEX\s*=\s*Object\.freeze\(\s*RENDER_ORDER_LAYER_STACK\.reduce\(/);
+    assert.match(geo(), /const\s+layerIndex\s*=\s*RENDER_ORDER_LAYER_INDEX\[layerName\]\s*;/);
+    assert.match(geo(), /if\s*\(\s*layerIndex\s*===\s*undefined\s*\)\s*throw\s+new\s+Error\(`Unknown 3D highway depth layer: \$\{layerName\}`\)\s*;/);
+    assert.match(geo(), /const\s+depthRenderOrder\s*=\s*Math\.max\(\s*RENDER_ORDER_FAR_CLAMP\s*,\s*Math\.round\(\s*RENDER_ORDER_AT_Z_ZERO\s*\+\s*worldZ\s*\/\s*K\s*\)\s*\)\s*;/);
     // Layer is a sub-unit fraction so the integer depth bucket strictly
     // dominates (a farther object can't outrank a nearer one via a higher
     // layer); the layer only breaks ties within the same depth bucket.
-    assert.match(src(), /return\s+depthRenderOrder\s*\+\s*layerIndex\s*\/\s*RENDER_ORDER_LAYER_STACK\.length\s*;/);
+    assert.match(geo(), /return\s+depthRenderOrder\s*\+\s*layerIndex\s*\/\s*RENDER_ORDER_LAYER_STACK\.length\s*;/);
     assert.ok(layerIndex('CHORD_FRAME') < layerIndex('NOTE_OUTLINE'));
 });