got-feedBack · byrongamatos · Jul 10, 2026 · Jul 10, 2026 · Jul 10, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -18,6 +18,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **The loop region, bar selection and scroll viewport moved to `src/loop.js`
+  (R2, step 28).** 528 lines: the A/B loop strip and its drag/nudge/keyboard
+  handling, bar-range selection, the scroll-bounds math, and `snapTime` — the one
+  place a raw time becomes a snapped one, which every timeline placement goes
+  through. `src/main.js` is down to 7,183 — **66%** below where it started.
+  Three main.js symbols arrive as host hooks (seek, snap step, Loop-in-3D
+  refresh); the loop-region and scroll functions and `snapTime` are themselves
+  host hooks now resolving here. Also removes a leftover dead `_guideTimerSync`
+  import in main.js from the audio step.
+
+
 - **The audio subsystem now lives in `src/audio.js` (R2, step 27).** 1,039 lines:
   the playback engine, the waveform, the onset strip, follow-scroll, and the
   WebAudio graph, plus the guide claps, the metronome, the A/B reference loop,

diff --git a/src/host.js b/src/host.js
@@ -114,6 +114,12 @@ export const host = {
      */
     finalizeActiveDrag: () => {},
 
+    // ── Seek and snap, for src/loop.js ────────────────────────────────
+    /** Move the cursor/transport to a chart time. */
+    editorSeekToTime: () => {},
+    /** The current snap step in seconds. */
+    editorSnapStepSeconds: () => 0,
+
     // ── Rendering and scroll, for src/audio.js ────────────────────────
     /** Force an immediate synchronous repaint (draw() is rAF-coalesced). */
     drawNow: () => {},

diff --git a/src/loop.js b/src/loop.js
diff --git a/src/main.js b/src/main.js
diff --git a/tests/group_move_snap.test.js b/tests/group_move_snap.test.js
@@ -22,10 +22,10 @@ const fs = require('fs');
 const path = require('path');
 const assert = require('assert');
 
-const src = fs.readFileSync(path.join(__dirname, '..', 'src', 'main.js'), 'utf8');
+const src = fs.readFileSync(path.join(__dirname, '..', 'src', 'loop.js'), 'utf8');
 const m = src.match(/\/\* @pure:group-time-delta:start[\s\S]*?@pure:group-time-delta:end \*\//);
 if (!m) { console.error('FAIL: @pure:group-time-delta block not found'); process.exit(1); }
-const { _groupTimeDeltaPure } = new Function('"use strict";' + m[0] + '\nreturn { _groupTimeDeltaPure };')();
+const { _groupTimeDeltaPure } = new Function('"use strict";' + m[0].replace(/^export\s+/gm, '') + '\nreturn { _groupTimeDeltaPure };')();
 
 // A 1/2-unit snap grid, and "snap off" (identity).
 const snapHalf = t => Math.round(t * 2) / 2;

diff --git a/tests/loop_ab.test.js b/tests/loop_ab.test.js
@@ -13,12 +13,12 @@ const path = require('path');
 const assert = require('assert');
 
 const src = fs.readFileSync(path.join(__dirname, '..', 'src', 'audio.js'), 'utf8');
-// _setLoopRegionEnabled stayed in main.js (it drives the loop-region UI, not the
-// audio engine); slice it from there when a case needs the real disarm path.
-const mainSrc = fs.readFileSync(path.join(__dirname, '..', 'src', 'main.js'), 'utf8');
+// _setLoopRegionEnabled moved to src/loop.js (the loop-region UI); slice it from
+// there when a case needs the real disarm path.
+const loopSrc = fs.readFileSync(path.join(__dirname, '..', 'src', 'loop.js'), 'utf8');
 const _m0 = src.match(/\/\* @pure:loop-ab:start \*\/[\s\S]*?\/\* @pure:loop-ab:end \*\//);
 if (!_m0) {
-    console.error('FAIL: @pure:loop-ab block not found in src/main.js');
+    console.error('FAIL: @pure:loop-ab block not found in src/audio.js');
     process.exit(1);
 }
 const m = [_m0[0].replace(/^export\s+/gm, '')];
@@ -154,9 +154,9 @@ function buildAB(opts) {
     // drives the true loop-disarm path (for the "restore ref on disable" test).
     let loopArm = '';
     if (opts.withLoopArm) {
-        const mm = mainSrc.match(/function _setLoopRegionEnabled\(enabled\) \{[\s\S]*?\n\}/);
+        const mm = loopSrc.match(/(?:export )?function _setLoopRegionEnabled\(enabled\) \{[\s\S]*?\n\}/);
         if (!mm) { console.error('FAIL: _setLoopRegionEnabled not found'); process.exit(1); }
-        loopArm = '\n' + mm[0];
+        loopArm = '\n' + mm[0].replace(/^export\s+/gm, '');
     }
     // The A/B runtime reaches main.js through `host` now; map its two methods to
     // the same spies the injected params used to be.

diff --git a/tests/loop_beats.test.mjs b/tests/loop_beats.test.mjs
@@ -31,7 +31,8 @@ import { setHostHooks } from '../src/host.js';
 import { S as realS } from '../src/state.js';
 import { TempoGridCmd } from '../src/tempo.js';
 
-const src = fs.readFileSync(new URL('../src/main.js', import.meta.url), 'utf8');
+// The loop-beats helpers moved to src/loop.js; slice them from there.
+const src = fs.readFileSync(new URL('../src/loop.js', import.meta.url), 'utf8');
 
 function extractFn(name) {
     const start = src.indexOf('function ' + name + '(');

diff --git a/tests/loop_nudge.test.mjs b/tests/loop_nudge.test.mjs
@@ -12,7 +12,7 @@
 import assert from 'node:assert';
 import fs from 'node:fs';
 
-const src = fs.readFileSync(new URL('../src/main.js', import.meta.url), 'utf8');
+const src = fs.readFileSync(new URL('../src/loop.js', import.meta.url), 'utf8');
 // The two loop pures moved to src/transport.js (#178). The rest of this file's
 // sliced @pure:loop-region block still calls them by name, so prepend their real
 // source to the slice — same scope, same behaviour, no re-implementation.
@@ -40,7 +40,7 @@ function extract(name) {
         '/\\* @pure:' + name + ':start \\*/[\\s\\S]*?/\\* @pure:' + name + ':end \\*/');
     const m = src.match(re);
     if (!m) { console.error(`FAIL: @pure:${name} block missing`); process.exit(1); }
-    return m[0];
+    return m[0].replace(/^export\s+/gm, '');
 }
 
 const api = new Function(

diff --git a/tests/loop_nudge_live.test.mjs b/tests/loop_nudge_live.test.mjs
@@ -17,7 +17,7 @@
 import assert from 'node:assert';
 import fs from 'node:fs';
 
-const src = fs.readFileSync(new URL('../src/main.js', import.meta.url), 'utf8');
+const src = fs.readFileSync(new URL('../src/loop.js', import.meta.url), 'utf8');
 // The two loop pures moved to src/transport.js (#178). The rest of this file's
 // sliced @pure:loop-region block still calls them by name, so prepend their real
 // source to the slice — same scope, same behaviour, no re-implementation.
@@ -45,12 +45,12 @@ function extract(name) {
         '/\\* @pure:' + name + ':start \\*/[\\s\\S]*?/\\* @pure:' + name + ':end \\*/');
     const m = src.match(re);
     if (!m) { console.error(`FAIL: @pure:${name} block missing`); process.exit(1); }
-    return m[0];
+    return m[0].replace(/^export\s+/gm, '');
 }
 function fn(name) {
-    const m = src.match(new RegExp('function ' + name + '\\([\\s\\S]*?\\n\\}'));
+    const m = src.match(new RegExp('(?:export )?function ' + name + '\\([\\s\\S]*?\\n\\}'));
     if (!m) { console.error(`FAIL: function ${name} not found`); process.exit(1); }
-    return m[0];
+    return m[0].replace(/^export\s+/gm, '');
 }
 
 const region = extract('loop-region');
@@ -66,23 +66,28 @@ const DUR = 10;
 function build({ barSel, pref = 'bar', snapEnabled = false, snapIdx = 1,
                  downbeats = DOWNBEATS, snapStep = 0.5, duration = DUR }) {
     const S = { barSel, beats: [], duration, snapEnabled, snapIdx };
+    // _loopNudgeEdge reaches main.js through `host` now (seek, snap step, the
+    // Loop-in-3D refresh, draw). Snap step comes from host.editorSnapStepSeconds.
+    const host = {
+        editorSnapStepSeconds: () => snapStep,
+        editorSeekToTime: () => {}, updateLoopIn3DBtn: () => {}, draw: () => {},
+    };
     const factory = new Function(
-        'S', '_downbeatTimes', '_loopSnapModePref', '_editorSnapStepSeconds',
+        'S', 'host', '_downbeatTimes', '_loopSnapModePref',
         'snapTime', 'SNAP_VALUES', '_editorEffectiveSnapValuePure',
-        '_updateLoopIn3DBtn', '_renderLoopStrip', 'draw', '_setBarSel',
+        '_renderLoopStrip', '_setBarSel',
         '"use strict";'
         + _loopPuresSrc() + region + '\n' + nudgePure + '\n' + liveModeSrc + '\n' + nudgeSrc
         + '\nreturn _loopNudgeEdge;'
     );
     const nudge = factory(
-        S,
+        S, host,
         () => downbeats,          // _downbeatTimes
         pref,                     // _loopSnapModePref
-        () => snapStep,           // _editorSnapStepSeconds
         (t) => t,                 // snapTime (identity)
         SNAP_VALUES,
         (en, v) => (en ? v : 0),  // _editorEffectiveSnapValuePure
-        () => {}, () => {}, () => {},
+        () => {},                 // _renderLoopStrip
         (r) => { S.barSel = r; return r; }   // _setBarSel: assign (β-sync isn't under test here)
     );
     return { S, nudge };

diff --git a/tests/loop_region.test.mjs b/tests/loop_region.test.mjs
@@ -1,12 +1,12 @@
 /*
- * Loop-region helper tests for src/main.js.
+ * Loop-region helper tests for src/loop.js.
  *
  * Run: node tests/loop_region.test.mjs
  */
 import assert from 'node:assert';
 import fs from 'node:fs';
 
-const src = fs.readFileSync(new URL('../src/main.js', import.meta.url), 'utf8');
+const src = fs.readFileSync(new URL('../src/loop.js', import.meta.url), 'utf8');
 // The two loop pures moved to src/transport.js (#178). The rest of this file's
 // sliced @pure:loop-region block still calls them by name, so prepend their real
 // source to the slice — same scope, same behaviour, no re-implementation.
@@ -29,11 +29,12 @@ function _loopPuresSrc() {
     return out.join('\n') + '\n';
 }
 
-const m = src.match(/\/\* @pure:loop-region:start \*\/[\s\S]*?\/\* @pure:loop-region:end \*\//);
-if (!m) {
-    console.error('FAIL: @pure:loop-region block not found in src/main.js');
+const _mRaw = src.match(/\/\* @pure:loop-region:start \*\/[\s\S]*?\/\* @pure:loop-region:end \*\//);
+if (!_mRaw) {
+    console.error('FAIL: @pure:loop-region block not found in src/loop.js');
     process.exit(1);
 }
+const m = [_mRaw[0].replace(/^export\s+/gm, '')];
 
 const api = new Function(
     '"use strict";' + _loopPuresSrc() + m[0] + '\nreturn { _barSpanForTimesPure, _adjustBarSelEdgePure, _normalizeLoopRegionPure, _loopPlaybackRestartTimePure };'

diff --git a/tests/loop_snap_modes.test.mjs b/tests/loop_snap_modes.test.mjs
@@ -19,7 +19,7 @@
 import assert from 'node:assert';
 import fs from 'node:fs';
 
-const src = fs.readFileSync(new URL('../src/main.js', import.meta.url), 'utf8');
+const src = fs.readFileSync(new URL('../src/loop.js', import.meta.url), 'utf8');
 // The two loop pures moved to src/transport.js (#178). The rest of this file's
 // sliced @pure:loop-region block still calls them by name, so prepend their real
 // source to the slice — same scope, same behaviour, no re-implementation.
@@ -42,11 +42,12 @@ function _loopPuresSrc() {
     return out.join('\n') + '\n';
 }
 
-const m = src.match(/\/\* @pure:loop-region:start \*\/[\s\S]*?\/\* @pure:loop-region:end \*\//);
-if (!m) {
-    console.error('FAIL: @pure:loop-region block not found in src/main.js');
+const _mRaw = src.match(/\/\* @pure:loop-region:start \*\/[\s\S]*?\/\* @pure:loop-region:end \*\//);
+if (!_mRaw) {
+    console.error('FAIL: @pure:loop-region block not found in src/loop.js');
     process.exit(1);
 }
+const m = [_mRaw[0].replace(/^export\s+/gm, '')];
 
 const api = new Function(
     '"use strict";' + _loopPuresSrc() + m[0]

diff --git a/tests/loop_undo_mode.test.mjs b/tests/loop_undo_mode.test.mjs
@@ -28,7 +28,10 @@ import { setHostHooks } from '../src/host.js';
 import { S as realS } from '../src/state.js';
 import { TempoMapCmd } from '../src/tempo.js';
 
-const src = fs.readFileSync(new URL('../src/main.js', import.meta.url), 'utf8');
+// The loop helpers moved to src/loop.js; the @pure:pending-view block stayed in
+// src/main.js. Slice each from its own source.
+const src = fs.readFileSync(new URL('../src/loop.js', import.meta.url), 'utf8');
+const mainSrc = fs.readFileSync(new URL('../src/main.js', import.meta.url), 'utf8');
 
 function extractFn(name) {
     const start = src.indexOf('function ' + name + '(');
@@ -43,7 +46,7 @@ function extractFn(name) {
 }
 
 // ── The A4 loop helpers are still inline in main.js; TempoMapCmd is imported ──
-const pm = src.match(/\/\* @pure:pending-view:start \*\/[\s\S]*?\/\* @pure:pending-view:end \*\//);
+const pm = mainSrc.match(/\/\* @pure:pending-view:start \*\/[\s\S]*?\/\* @pure:pending-view:end \*\//);
 if (!pm) { console.error('FAIL: @pure:pending-view block not found'); process.exit(1); }
 
 const { _resolvePendingViewStatePure } = new Function(

diff --git a/tests/onset_snap.test.js b/tests/onset_snap.test.js
@@ -19,9 +19,9 @@ const fs = require('fs');
 const path = require('path');
 const assert = require('assert');
 
-// @pure:onset-snap moved to src/audio.js; snapTime is still in src/main.js.
+// @pure:onset-snap moved to src/audio.js; snapTime moved to src/loop.js.
 const src = fs.readFileSync(path.join(__dirname, '..', 'src', 'audio.js'), 'utf8');
-const mainSrc = fs.readFileSync(path.join(__dirname, '..', 'src', 'main.js'), 'utf8');
+const mainSrc = fs.readFileSync(path.join(__dirname, '..', 'src', 'loop.js'), 'utf8');
 
 const _m0 = src.match(/\/\* @pure:onset-snap:start \*\/[\s\S]*?\/\* @pure:onset-snap:end \*\//);
 if (!_m0) {
@@ -33,7 +33,7 @@ const { _nearestOnsetTimePure } = new Function(
     '"use strict";' + m[0] + '\nreturn { _nearestOnsetTimePure };'
 )();
 
-// Extract snapTime by name (brace matching — the tempo_beat_drag harness) and
+// Extract snapTime (moved to src/loop.js) by name (brace matching) and
 // inject its free identifiers so we can drive the onset-vs-grid routing.
 function extractFn(name) {
     const start = mainSrc.indexOf('function ' + name);