diff --git a/src/components/ChordPickerPopup.tsx b/src/components/ChordPickerPopup.tsx
index 68c1f9f..35c08ea 100644
--- a/src/components/ChordPickerPopup.tsx
+++ b/src/components/ChordPickerPopup.tsx
@@ -65,7 +65,7 @@ function createFallbackDescriptor(value: string): ChordDescriptor {
 }
 
 function normalizeDescriptor(descriptor: ChordDescriptor): ChordDescriptor {
-  let quality = descriptor.quality;
+  const quality = descriptor.quality;
   let extensions = [...descriptor.extensions];
 
   const dedupe = (nextExtensions: ChordExtension[]) => Array.from(new Set(nextExtensions));
diff --git a/src/components/KGOnePanel.tsx b/src/components/KGOnePanel.tsx
index 5272efb..7f86e6b 100644
--- a/src/components/KGOnePanel.tsx
+++ b/src/components/KGOnePanel.tsx
@@ -79,11 +79,11 @@ function formatKGOneTabLabel(tab: Tab): string {
   return 'Separator';
 }
 
-export function getDefaultKGOneTab(mode: KGOneMode): Tab {
+function getDefaultKGOneTab(mode: KGOneMode): Tab {
   return mode === 'local-separator' ? 'separator' : 'fullsong';
 }
 
-export function getKGOneMode(): KGOneMode {
+function getKGOneMode(): KGOneMode {
   const enabled = (ConfigManager.instance().get('general.kgone.enabled') as boolean | undefined) ?? false;
   return enabled ? 'server' : 'local-separator';
 }
diff --git a/src/components/MainContent.tsx b/src/components/MainContent.tsx
index bc67358..6f98476 100644
--- a/src/components/MainContent.tsx
+++ b/src/components/MainContent.tsx
@@ -1270,7 +1270,7 @@ const MainContent: React.FC<MainContentProps> = ({
     }
 
     const sortedRegions = [...chordRegions]
-      .sort((left, right) => left.getStartFromBeat() - right.getStartFromBeat())
+      .sort((left, right) => left.getStartFromBeat() - right.getStartFromBeat());
     const targetRegion = direction === 'forward'
       ? sortedRegions.find(region => region.getStartFromBeat() > currentStartBeat && region.getStartFromBeat() <= targetBarBeat)
       : [...sortedRegions]
diff --git a/src/components/piano-roll/PianoRoll.test.ts b/src/components/piano-roll/PianoRoll.test.ts
index 1a4b761..2ba3ef6 100644
--- a/src/components/piano-roll/PianoRoll.test.ts
+++ b/src/components/piano-roll/PianoRoll.test.ts
@@ -36,7 +36,7 @@ import {
   getRegionStartScrollLeft,
   getRegionPlayheadRelation,
   getScrollLeftForViewportRequest,
-} from './PianoRoll';
+} from './pianoRollViewport';
 import type { SheetMeasureMetric } from './sheetNotationTypes';
 
 function createContainer({ clientWidth, scrollWidth }: { clientWidth: number; scrollWidth: number }): HTMLDivElement {
diff --git a/src/components/piano-roll/PianoRoll.tsx b/src/components/piano-roll/PianoRoll.tsx
index fac6e52..0da1aee 100644
--- a/src/components/piano-roll/PianoRoll.tsx
+++ b/src/components/piano-roll/PianoRoll.tsx
@@ -25,37 +25,12 @@ import {
 import type { PianoRollAutomationType } from './pianoRollAutomation';
 import type { SheetMeasureMetric } from './sheetNotationTypes';
 import { getSheetPlayheadPixel, getSheetQuantizationOptions, parseSheetQuantization } from './sheetNotation';
-
-type RegionPlayheadRelation = 'before' | 'inside' | 'after';
-type ViewportSwitchAlignment = 'center' | 'region-start' | 'region-end';
-type ViewportClampScope = 'region' | 'track';
-
-interface PendingModeSwitchRequest {
-  sourceSheetMusicViewEnabled: boolean;
-  destinationSheetMusicViewEnabled: boolean;
-  destinationSheetMusicTrackScopeEnabled: boolean;
-  alignment: ViewportSwitchAlignment;
-  anchorBeat: number;
-  clampScope: ViewportClampScope;
-}
-
-interface ModeSwitchRequestOptions {
-  playheadBeat: number;
-  regionStartBeat: number;
-  regionEndBeat: number;
-  sourceSheetMusicViewEnabled: boolean;
-  destinationSheetMusicViewEnabled: boolean;
-  destinationSheetMusicTrackScopeEnabled: boolean;
-}
-
-interface ScrollLeftForViewportRequestOptions {
-  request: PendingModeSwitchRequest;
-  container: HTMLDivElement;
-  sheetMeasureMetrics: SheetMeasureMetric[];
-  activeRegionStartBeat: number;
-  activeRegionEndBeat: number;
-  songEndBeat: number;
-}
+import {
+  createPendingModeSwitchRequest,
+  getRegionStartScrollLeft,
+  getScrollLeftForViewportRequest,
+  type PendingModeSwitchRequest,
+} from './pianoRollViewport';
 
 interface PianoRollProps {
   onClose: () => void;
@@ -1389,233 +1364,3 @@ const PianoRoll: React.FC<PianoRollProps> = ({
 };
 
 export default PianoRoll; 
-
-export function getRegionPlayheadRelation(
-  playheadBeat: number,
-  regionStartBeat: number,
-  regionEndBeat: number
-): RegionPlayheadRelation {
-  if (playheadBeat < regionStartBeat) {
-    return 'before';
-  }
-
-  if (playheadBeat > regionEndBeat) {
-    return 'after';
-  }
-
-  return 'inside';
-}
-
-export function createPendingModeSwitchRequest({
-  playheadBeat,
-  regionStartBeat,
-  regionEndBeat,
-  sourceSheetMusicViewEnabled,
-  destinationSheetMusicViewEnabled,
-  destinationSheetMusicTrackScopeEnabled,
-}: ModeSwitchRequestOptions): PendingModeSwitchRequest {
-  const relation = getRegionPlayheadRelation(playheadBeat, regionStartBeat, regionEndBeat);
-  const enteringTrackScopeSheet = (
-    !sourceSheetMusicViewEnabled &&
-    destinationSheetMusicViewEnabled &&
-    destinationSheetMusicTrackScopeEnabled
-  );
-
-  if (relation === 'inside') {
-    return {
-      sourceSheetMusicViewEnabled,
-      destinationSheetMusicViewEnabled,
-      destinationSheetMusicTrackScopeEnabled,
-      alignment: 'center',
-      anchorBeat: playheadBeat,
-      clampScope: destinationSheetMusicTrackScopeEnabled ? 'track' : 'region',
-    };
-  }
-
-  if (enteringTrackScopeSheet) {
-    return {
-      sourceSheetMusicViewEnabled,
-      destinationSheetMusicViewEnabled,
-      destinationSheetMusicTrackScopeEnabled,
-      alignment: 'center',
-      anchorBeat: playheadBeat,
-      clampScope: 'track',
-    };
-  }
-
-  return {
-    sourceSheetMusicViewEnabled,
-    destinationSheetMusicViewEnabled,
-    destinationSheetMusicTrackScopeEnabled,
-    alignment: relation === 'before' ? 'region-start' : 'region-end',
-    anchorBeat: relation === 'before' ? regionStartBeat : regionEndBeat,
-    clampScope: 'region',
-  };
-}
-
-function getHorizontalViewportMetrics(container: HTMLDivElement, sheetMusicViewEnabled: boolean): {
-  visibleWidth: number;
-  keysWidth: number;
-} {
-  const keysWidth = sheetMusicViewEnabled
-    ? 0
-    : (parseInt(
-        getComputedStyle(document.documentElement).getPropertyValue('--region-piano-key-width')
-      ) || 60);
-
-  return {
-    visibleWidth: Math.max(0, container.clientWidth - keysWidth),
-    keysWidth,
-  };
-}
-
-function getPixelForAbsoluteBeat(
-  beat: number,
-  sheetMusicViewEnabled: boolean,
-  sheetMusicTrackScopeEnabled: boolean,
-  sheetMeasureMetrics: SheetMeasureMetric[],
-  activeRegionStartBeat: number
-): number {
-  if (sheetMusicViewEnabled) {
-    return getSheetPlayheadPixel(
-      sheetMusicTrackScopeEnabled
-        ? Math.max(0, beat)
-        : Math.max(0, beat - activeRegionStartBeat),
-      sheetMeasureMetrics
-    );
-  }
-
-  const beatWidth = parseInt(
-    getComputedStyle(document.documentElement).getPropertyValue('--region-grid-beat-width')
-  ) || 40;
-  return beat * beatWidth;
-}
-
-function getScopeBoundsInPixels(
-  request: PendingModeSwitchRequest,
-  sheetMeasureMetrics: SheetMeasureMetric[],
-  activeRegionStartBeat: number,
-  activeRegionEndBeat: number,
-  songEndBeat: number
-): { startPx: number; endPx: number } {
-  if (request.destinationSheetMusicViewEnabled) {
-    if (request.clampScope === 'track') {
-      return {
-        startPx: getSheetPlayheadPixel(0, sheetMeasureMetrics),
-        endPx: getSheetPlayheadPixel(songEndBeat, sheetMeasureMetrics),
-      };
-    }
-
-    return {
-      startPx: getSheetPlayheadPixel(0, sheetMeasureMetrics),
-      endPx: getSheetPlayheadPixel(activeRegionEndBeat - activeRegionStartBeat, sheetMeasureMetrics),
-    };
-  }
-
-  const beatWidth = parseInt(
-    getComputedStyle(document.documentElement).getPropertyValue('--region-grid-beat-width')
-  ) || 40;
-
-  if (request.clampScope === 'track') {
-    return {
-      startPx: 0,
-      endPx: songEndBeat * beatWidth,
-    };
-  }
-
-  return {
-    startPx: activeRegionStartBeat * beatWidth,
-    endPx: activeRegionEndBeat * beatWidth,
-  };
-}
-
-function clampScrollLeftToContainer(container: HTMLDivElement, scrollLeft: number): number {
-  return Math.max(0, Math.min(scrollLeft, container.scrollWidth - container.clientWidth));
-}
-
-function getCenteredScrollLeft({
-  pixelPosition,
-  visibleWidth,
-  scopeStartPx,
-  scopeEndPx,
-  container,
-}: {
-  pixelPosition: number;
-  visibleWidth: number;
-  scopeStartPx: number;
-  scopeEndPx: number;
-  container: HTMLDivElement;
-}): number {
-  const unclamped = pixelPosition - visibleWidth / 2;
-  const maxScopeScrollLeft = Math.max(scopeStartPx, scopeEndPx - visibleWidth);
-  const clampedToScope = Math.max(scopeStartPx, Math.min(unclamped, maxScopeScrollLeft));
-  return clampScrollLeftToContainer(container, clampedToScope);
-}
-
-function getRegionEndAlignedScrollLeft({
-  visibleWidth,
-  scopeEndPx,
-  container,
-}: {
-  visibleWidth: number;
-  scopeEndPx: number;
-  container: HTMLDivElement;
-}): number {
-  return clampScrollLeftToContainer(container, Math.max(0, scopeEndPx - visibleWidth));
-}
-
-export function getScrollLeftForViewportRequest({
-  request,
-  container,
-  sheetMeasureMetrics,
-  activeRegionStartBeat,
-  activeRegionEndBeat,
-  songEndBeat,
-}: ScrollLeftForViewportRequestOptions): number {
-  const { visibleWidth } = getHorizontalViewportMetrics(
-    container,
-    request.destinationSheetMusicViewEnabled
-  );
-  const pixelPosition = getPixelForAbsoluteBeat(
-    request.anchorBeat,
-    request.destinationSheetMusicViewEnabled,
-    request.destinationSheetMusicTrackScopeEnabled,
-    sheetMeasureMetrics,
-    activeRegionStartBeat
-  );
-  const { startPx, endPx } = getScopeBoundsInPixels(
-    request,
-    sheetMeasureMetrics,
-    activeRegionStartBeat,
-    activeRegionEndBeat,
-    songEndBeat
-  );
-
-  if (request.alignment === 'region-start') {
-    return clampScrollLeftToContainer(container, startPx);
-  }
-
-  if (request.alignment === 'region-end') {
-    return getRegionEndAlignedScrollLeft({
-      visibleWidth,
-      scopeEndPx: endPx,
-      container,
-    });
-  }
-
-  return getCenteredScrollLeft({
-    pixelPosition,
-    visibleWidth,
-    scopeStartPx: startPx,
-    scopeEndPx: endPx,
-    container,
-  });
-}
-
-export function getRegionStartScrollLeft(startBeat: number): number {
-  const beatWidth = parseInt(
-    getComputedStyle(document.documentElement).getPropertyValue('--region-grid-beat-width')
-  ) || TOOLBAR_CONSTANTS.BASE_BAR_WIDTH;
-
-  return Math.max(0, startBeat * beatWidth);
-}
diff --git a/src/components/piano-roll/PianoRollAutomationLane.tsx b/src/components/piano-roll/PianoRollAutomationLane.tsx
index 32b4427..44e1eda 100644
--- a/src/components/piano-roll/PianoRollAutomationLane.tsx
+++ b/src/components/piano-roll/PianoRollAutomationLane.tsx
@@ -613,7 +613,7 @@ const PianoRollAutomationLane: React.FC<PianoRollAutomationLaneProps> = ({
       return;
     }
 
-    let nextSelection = lassoShiftKeyRef.current ? new Set(selectedPointIdSet) : new Set<string>();
+    const nextSelection = lassoShiftKeyRef.current ? new Set(selectedPointIdSet) : new Set<string>();
 
     renderedPointsSorted.forEach(point => {
       const isIntersecting = (
diff --git a/src/components/piano-roll/SheetMusicView.test.tsx b/src/components/piano-roll/SheetMusicView.test.tsx
index eda0754..dc59f04 100644
--- a/src/components/piano-roll/SheetMusicView.test.tsx
+++ b/src/components/piano-roll/SheetMusicView.test.tsx
@@ -74,8 +74,8 @@ vi.mock('vexflow', () => {
       return this;
     }
 
-    addKeySignature() {
-      vexflowMocks.addKeySignatureMock(...arguments);
+    addKeySignature(...args: unknown[]) {
+      vexflowMocks.addKeySignatureMock(...args);
       return this;
     }
 
diff --git a/src/components/piano-roll/pianoRollViewport.ts b/src/components/piano-roll/pianoRollViewport.ts
new file mode 100644
index 0000000..7fba92b
--- /dev/null
+++ b/src/components/piano-roll/pianoRollViewport.ts
@@ -0,0 +1,264 @@
+import { TOOLBAR_CONSTANTS } from '../../constants';
+import type { SheetMeasureMetric } from './sheetNotationTypes';
+import { getSheetPlayheadPixel } from './sheetNotation';
+
+export type RegionPlayheadRelation = 'before' | 'inside' | 'after';
+type ViewportSwitchAlignment = 'center' | 'region-start' | 'region-end';
+type ViewportClampScope = 'region' | 'track';
+
+export interface PendingModeSwitchRequest {
+  sourceSheetMusicViewEnabled: boolean;
+  destinationSheetMusicViewEnabled: boolean;
+  destinationSheetMusicTrackScopeEnabled: boolean;
+  alignment: ViewportSwitchAlignment;
+  anchorBeat: number;
+  clampScope: ViewportClampScope;
+}
+
+export interface ModeSwitchRequestOptions {
+  playheadBeat: number;
+  regionStartBeat: number;
+  regionEndBeat: number;
+  sourceSheetMusicViewEnabled: boolean;
+  destinationSheetMusicViewEnabled: boolean;
+  destinationSheetMusicTrackScopeEnabled: boolean;
+}
+
+export interface ScrollLeftForViewportRequestOptions {
+  request: PendingModeSwitchRequest;
+  container: HTMLDivElement;
+  sheetMeasureMetrics: SheetMeasureMetric[];
+  activeRegionStartBeat: number;
+  activeRegionEndBeat: number;
+  songEndBeat: number;
+}
+
+export function getRegionPlayheadRelation(
+  playheadBeat: number,
+  regionStartBeat: number,
+  regionEndBeat: number
+): RegionPlayheadRelation {
+  if (playheadBeat < regionStartBeat) {
+    return 'before';
+  }
+
+  if (playheadBeat > regionEndBeat) {
+    return 'after';
+  }
+
+  return 'inside';
+}
+
+export function createPendingModeSwitchRequest({
+  playheadBeat,
+  regionStartBeat,
+  regionEndBeat,
+  sourceSheetMusicViewEnabled,
+  destinationSheetMusicViewEnabled,
+  destinationSheetMusicTrackScopeEnabled,
+}: ModeSwitchRequestOptions): PendingModeSwitchRequest {
+  const relation = getRegionPlayheadRelation(playheadBeat, regionStartBeat, regionEndBeat);
+  const enteringTrackScopeSheet = (
+    !sourceSheetMusicViewEnabled &&
+    destinationSheetMusicViewEnabled &&
+    destinationSheetMusicTrackScopeEnabled
+  );
+
+  if (relation === 'inside') {
+    return {
+      sourceSheetMusicViewEnabled,
+      destinationSheetMusicViewEnabled,
+      destinationSheetMusicTrackScopeEnabled,
+      alignment: 'center',
+      anchorBeat: playheadBeat,
+      clampScope: destinationSheetMusicTrackScopeEnabled ? 'track' : 'region',
+    };
+  }
+
+  if (enteringTrackScopeSheet) {
+    return {
+      sourceSheetMusicViewEnabled,
+      destinationSheetMusicViewEnabled,
+      destinationSheetMusicTrackScopeEnabled,
+      alignment: 'center',
+      anchorBeat: playheadBeat,
+      clampScope: 'track',
+    };
+  }
+
+  return {
+    sourceSheetMusicViewEnabled,
+    destinationSheetMusicViewEnabled,
+    destinationSheetMusicTrackScopeEnabled,
+    alignment: relation === 'before' ? 'region-start' : 'region-end',
+    anchorBeat: relation === 'before' ? regionStartBeat : regionEndBeat,
+    clampScope: 'region',
+  };
+}
+
+function getHorizontalViewportMetrics(container: HTMLDivElement, sheetMusicViewEnabled: boolean): {
+  visibleWidth: number;
+  keysWidth: number;
+} {
+  const keysWidth = sheetMusicViewEnabled
+    ? 0
+    : (parseInt(
+        getComputedStyle(document.documentElement).getPropertyValue('--region-piano-key-width')
+      ) || 60);
+
+  return {
+    visibleWidth: Math.max(0, container.clientWidth - keysWidth),
+    keysWidth,
+  };
+}
+
+function getPixelForAbsoluteBeat(
+  beat: number,
+  sheetMusicViewEnabled: boolean,
+  sheetMusicTrackScopeEnabled: boolean,
+  sheetMeasureMetrics: SheetMeasureMetric[],
+  activeRegionStartBeat: number
+): number {
+  if (sheetMusicViewEnabled) {
+    return getSheetPlayheadPixel(
+      sheetMusicTrackScopeEnabled
+        ? Math.max(0, beat)
+        : Math.max(0, beat - activeRegionStartBeat),
+      sheetMeasureMetrics
+    );
+  }
+
+  const beatWidth = parseInt(
+    getComputedStyle(document.documentElement).getPropertyValue('--region-grid-beat-width')
+  ) || 40;
+  return beat * beatWidth;
+}
+
+function getScopeBoundsInPixels(
+  request: PendingModeSwitchRequest,
+  sheetMeasureMetrics: SheetMeasureMetric[],
+  activeRegionStartBeat: number,
+  activeRegionEndBeat: number,
+  songEndBeat: number
+): { startPx: number; endPx: number } {
+  if (request.destinationSheetMusicViewEnabled) {
+    if (request.clampScope === 'track') {
+      return {
+        startPx: getSheetPlayheadPixel(0, sheetMeasureMetrics),
+        endPx: getSheetPlayheadPixel(songEndBeat, sheetMeasureMetrics),
+      };
+    }
+
+    return {
+      startPx: getSheetPlayheadPixel(0, sheetMeasureMetrics),
+      endPx: getSheetPlayheadPixel(activeRegionEndBeat - activeRegionStartBeat, sheetMeasureMetrics),
+    };
+  }
+
+  const beatWidth = parseInt(
+    getComputedStyle(document.documentElement).getPropertyValue('--region-grid-beat-width')
+  ) || 40;
+
+  if (request.clampScope === 'track') {
+    return {
+      startPx: 0,
+      endPx: songEndBeat * beatWidth,
+    };
+  }
+
+  return {
+    startPx: activeRegionStartBeat * beatWidth,
+    endPx: activeRegionEndBeat * beatWidth,
+  };
+}
+
+function clampScrollLeftToContainer(container: HTMLDivElement, scrollLeft: number): number {
+  return Math.max(0, Math.min(scrollLeft, container.scrollWidth - container.clientWidth));
+}
+
+function getCenteredScrollLeft({
+  pixelPosition,
+  visibleWidth,
+  scopeStartPx,
+  scopeEndPx,
+  container,
+}: {
+  pixelPosition: number;
+  visibleWidth: number;
+  scopeStartPx: number;
+  scopeEndPx: number;
+  container: HTMLDivElement;
+}): number {
+  const unclamped = pixelPosition - visibleWidth / 2;
+  const maxScopeScrollLeft = Math.max(scopeStartPx, scopeEndPx - visibleWidth);
+  const clampedToScope = Math.max(scopeStartPx, Math.min(unclamped, maxScopeScrollLeft));
+  return clampScrollLeftToContainer(container, clampedToScope);
+}
+
+function getRegionEndAlignedScrollLeft({
+  visibleWidth,
+  scopeEndPx,
+  container,
+}: {
+  visibleWidth: number;
+  scopeEndPx: number;
+  container: HTMLDivElement;
+}): number {
+  return clampScrollLeftToContainer(container, Math.max(0, scopeEndPx - visibleWidth));
+}
+
+export function getScrollLeftForViewportRequest({
+  request,
+  container,
+  sheetMeasureMetrics,
+  activeRegionStartBeat,
+  activeRegionEndBeat,
+  songEndBeat,
+}: ScrollLeftForViewportRequestOptions): number {
+  const { visibleWidth } = getHorizontalViewportMetrics(
+    container,
+    request.destinationSheetMusicViewEnabled
+  );
+  const pixelPosition = getPixelForAbsoluteBeat(
+    request.anchorBeat,
+    request.destinationSheetMusicViewEnabled,
+    request.destinationSheetMusicTrackScopeEnabled,
+    sheetMeasureMetrics,
+    activeRegionStartBeat
+  );
+  const { startPx, endPx } = getScopeBoundsInPixels(
+    request,
+    sheetMeasureMetrics,
+    activeRegionStartBeat,
+    activeRegionEndBeat,
+    songEndBeat
+  );
+
+  if (request.alignment === 'region-start') {
+    return clampScrollLeftToContainer(container, startPx);
+  }
+
+  if (request.alignment === 'region-end') {
+    return getRegionEndAlignedScrollLeft({
+      visibleWidth,
+      scopeEndPx: endPx,
+      container,
+    });
+  }
+
+  return getCenteredScrollLeft({
+    pixelPosition,
+    visibleWidth,
+    scopeStartPx: startPx,
+    scopeEndPx: endPx,
+    container,
+  });
+}
+
+export function getRegionStartScrollLeft(startBeat: number): number {
+  const beatWidth = parseInt(
+    getComputedStyle(document.documentElement).getPropertyValue('--region-grid-beat-width')
+  ) || TOOLBAR_CONSTANTS.BASE_BAR_WIDTH;
+
+  return Math.max(0, startBeat * beatWidth);
+}
diff --git a/src/components/track/TrackAutomationLane.test.ts b/src/components/track/TrackAutomationLane.test.ts
index e73ba0b..95db842 100644
--- a/src/components/track/TrackAutomationLane.test.ts
+++ b/src/components/track/TrackAutomationLane.test.ts
@@ -15,7 +15,7 @@ vi.mock('../../stores/projectStore', () => ({
   }),
 }));
 
-const { __trackAutomationTestUtils } = await import('./TrackAutomationLane');
+const __trackAutomationTestUtils = await import('./trackAutomationLaneUtils');
 
 describe('TrackAutomationLane mapping', () => {
   it('maps volume 0.0dB to the visual midpoint and back', () => {
diff --git a/src/components/track/TrackAutomationLane.tsx b/src/components/track/TrackAutomationLane.tsx
index fff95da..e4c205f 100644
--- a/src/components/track/TrackAutomationLane.tsx
+++ b/src/components/track/TrackAutomationLane.tsx
@@ -11,6 +11,14 @@ import { PIANO_ROLL_CONSTANTS } from '../../constants';
 import { AUDIO_INTERFACE_CONSTANTS } from '../../constants/coreConstants';
 import { isModifierKeyPressed } from '../../util/osUtil';
 import { KGMainContentState } from '../../core/state/KGMainContentState';
+import {
+  formatAutomationValue,
+  getLaneMetrics,
+  volumeToY,
+  yToVolume,
+  panToY,
+  yToPan,
+} from './trackAutomationLaneUtils';
 
 interface TrackAutomationLaneProps {
   track: KGTrack;
@@ -32,7 +40,6 @@ interface PreviewPoint {
   value: number;
 }
 
-const LANE_PADDING_Y = 12;
 const POINT_RADIUS = 5;
 const SELECTED_POINT_COLOR = '#FFFFFF';
 const TRACK_AUTOMATION_COLORS: Record<TrackAutomationType, string> = {
@@ -40,105 +47,6 @@ const TRACK_AUTOMATION_COLORS: Record<TrackAutomationType, string> = {
   pan: '#90EE90',
 };
 
-function formatAutomationValue(automationType: TrackAutomationType, value: number): string {
-  if (automationType === 'volume') {
-    if (value <= AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB) {
-      return '−∞';
-    }
-
-    return `${value >= 0 ? '+' : ''}${value.toFixed(1)}dB`;
-  }
-
-  const logicPanValue = value <= 0
-    ? Math.round(value * 64)
-    : Math.round(value * 63);
-  return `${logicPanValue >= 0 ? '+' : ''}${logicPanValue}`;
-}
-
-function getLaneMetrics(laneHeight: number) {
-  const top = LANE_PADDING_Y;
-  const bottom = laneHeight - LANE_PADDING_Y;
-  const middle = Math.round((top + bottom) / 2);
-  return { top, middle, bottom };
-}
-
-function volumeToY(value: number, laneHeight: number): number {
-  const clamped = Math.max(
-    AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB,
-    Math.min(AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB, value)
-  );
-  const { top, middle, bottom } = getLaneMetrics(laneHeight);
-
-  if (clamped >= 0) {
-    const normalized = clamped / AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB;
-    return middle - (middle - top) * normalized;
-  }
-
-  const normalized = clamped / AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB;
-  return middle + (bottom - middle) * normalized;
-}
-
-function yToVolume(y: number, laneHeight: number): number {
-  const { top, middle, bottom } = getLaneMetrics(laneHeight);
-  const clampedY = Math.min(bottom, Math.max(top, y));
-
-  if (clampedY <= middle) {
-    const normalized = middle === top ? 0 : (middle - clampedY) / (middle - top);
-    return Math.min(
-      AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB,
-      Math.max(0, normalized * AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB)
-    );
-  }
-
-  const normalized = bottom === middle ? 0 : (clampedY - middle) / (bottom - middle);
-  return Math.max(
-    AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB,
-    Math.min(0, normalized * AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB)
-  );
-}
-
-function panToY(value: number, laneHeight: number): number {
-  const clamped = Math.max(-1, Math.min(1, value));
-  const { top, middle, bottom } = getLaneMetrics(laneHeight);
-
-  if (clamped === 0) {
-    return middle;
-  }
-
-  if (clamped > 0) {
-    return middle - (middle - top) * clamped;
-  }
-
-  return middle + (bottom - middle) * Math.abs(clamped);
-}
-
-function yToPan(y: number, laneHeight: number): number {
-  const { top, middle, bottom } = getLaneMetrics(laneHeight);
-  const clampedY = Math.min(bottom, Math.max(top, y));
-
-  // Reserve a full pixel around the midpoint for exact center.
-  if (Math.abs(clampedY - middle) <= 0.5) {
-    return 0;
-  }
-
-  if (clampedY < middle) {
-    const normalized = middle === top ? 0 : (middle - clampedY) / (middle - top);
-    return Math.max(0, Math.min(1, normalized));
-  }
-
-  const normalized = bottom === middle ? 0 : (clampedY - middle) / (bottom - middle);
-  return Math.max(-1, Math.min(0, -normalized));
-}
-
-export const __trackAutomationTestUtils = {
-  formatAutomationValue,
-  getLaneMetrics,
-  volumeToY,
-  yToVolume,
-  panToY,
-  yToPan,
-};
-
 const TrackAutomationLane: React.FC<TrackAutomationLaneProps> = ({
   track,
   automationType,
@@ -467,7 +375,7 @@ const TrackAutomationLane: React.FC<TrackAutomationLaneProps> = ({
       return;
     }
 
-    let nextSelection = lassoShiftKeyRef.current ? new Set(selectedPointIdSet) : new Set<string>();
+    const nextSelection = lassoShiftKeyRef.current ? new Set(selectedPointIdSet) : new Set<string>();
     renderedPoints.forEach(point => {
       const isIntersecting = (
         point.x + POINT_RADIUS >= left &&
diff --git a/src/components/track/trackAutomationLaneUtils.ts b/src/components/track/trackAutomationLaneUtils.ts
new file mode 100644
index 0000000..8dd3b2e
--- /dev/null
+++ b/src/components/track/trackAutomationLaneUtils.ts
@@ -0,0 +1,93 @@
+import { AUDIO_INTERFACE_CONSTANTS } from '../../constants/coreConstants';
+import type { TrackAutomationType } from '../../core/track/KGTrackAutomationPoint';
+
+const LANE_PADDING_Y = 12;
+
+export function formatAutomationValue(automationType: TrackAutomationType, value: number): string {
+  if (automationType === 'volume') {
+    if (value <= AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB) {
+      return '−∞';
+    }
+
+    return `${value >= 0 ? '+' : ''}${value.toFixed(1)}dB`;
+  }
+
+  const logicPanValue = value <= 0
+    ? Math.round(value * 64)
+    : Math.round(value * 63);
+  return `${logicPanValue >= 0 ? '+' : ''}${logicPanValue}`;
+}
+
+export function getLaneMetrics(laneHeight: number) {
+  const top = LANE_PADDING_Y;
+  const bottom = laneHeight - LANE_PADDING_Y;
+  const middle = Math.round((top + bottom) / 2);
+  return { top, middle, bottom };
+}
+
+export function volumeToY(value: number, laneHeight: number): number {
+  const clamped = Math.max(
+    AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB,
+    Math.min(AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB, value)
+  );
+  const { top, middle, bottom } = getLaneMetrics(laneHeight);
+
+  if (clamped >= 0) {
+    const normalized = clamped / AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB;
+    return middle - (middle - top) * normalized;
+  }
+
+  const normalized = clamped / AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB;
+  return middle + (bottom - middle) * normalized;
+}
+
+export function yToVolume(y: number, laneHeight: number): number {
+  const { top, middle, bottom } = getLaneMetrics(laneHeight);
+  const clampedY = Math.min(bottom, Math.max(top, y));
+
+  if (clampedY <= middle) {
+    const normalized = middle === top ? 0 : (middle - clampedY) / (middle - top);
+    return Math.min(
+      AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB,
+      Math.max(0, normalized * AUDIO_INTERFACE_CONSTANTS.MAX_TRACK_VOLUME_DB)
+    );
+  }
+
+  const normalized = bottom === middle ? 0 : (clampedY - middle) / (bottom - middle);
+  return Math.max(
+    AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB,
+    Math.min(0, normalized * AUDIO_INTERFACE_CONSTANTS.MIN_TRACK_VOLUME_DB)
+  );
+}
+
+export function panToY(value: number, laneHeight: number): number {
+  const clamped = Math.max(-1, Math.min(1, value));
+  const { top, middle, bottom } = getLaneMetrics(laneHeight);
+
+  if (clamped === 0) {
+    return middle;
+  }
+
+  if (clamped > 0) {
+    return middle - (middle - top) * clamped;
+  }
+
+  return middle + (bottom - middle) * Math.abs(clamped);
+}
+
+export function yToPan(y: number, laneHeight: number): number {
+  const { top, middle, bottom } = getLaneMetrics(laneHeight);
+  const clampedY = Math.min(bottom, Math.max(top, y));
+
+  if (Math.abs(clampedY - middle) <= 0.5) {
+    return 0;
+  }
+
+  if (clampedY < middle) {
+    const normalized = middle === top ? 0 : (middle - clampedY) / (middle - top);
+    return Math.max(0, Math.min(1, normalized));
+  }
+
+  const normalized = bottom === middle ? 0 : (clampedY - middle) / (bottom - middle);
+  return Math.max(-1, Math.min(0, -normalized));
+}
diff --git a/src/util/localSeparatorGpuDsp.ts b/src/util/localSeparatorGpuDsp.ts
index c3f70dc..41cb0e4 100644
--- a/src/util/localSeparatorGpuDsp.ts
+++ b/src/util/localSeparatorGpuDsp.ts
@@ -10,12 +10,73 @@ function localSeparatorLog(message: string, payload?: unknown): void {
   console.log(`[localSeparator] ${message}`, payload);
 }
 
-type GPUDeviceLike = any;
-type GPUBufferLike = any;
-type GPUComputePipelineLike = any;
+interface GPUBufferLike {
+  destroy(): void;
+  mapAsync(mode: number): Promise<void>;
+  getMappedRange(): ArrayBuffer;
+  unmap(): void;
+}
 
-declare const GPUBufferUsage: any;
-declare const GPUMapMode: any;
+interface GPUComputePassEncoderLike {
+  setPipeline(pipeline: GPUComputePipelineLike): void;
+  setBindGroup(index: number, bindGroup: unknown): void;
+  dispatchWorkgroups(x: number): void;
+  end(): void;
+}
+
+interface GPUCommandEncoderLike {
+  copyBufferToBuffer(source: GPUBufferLike, sourceOffset: number, destination: GPUBufferLike, destinationOffset: number, size: number): void;
+  beginComputePass(): GPUComputePassEncoderLike;
+  finish(): unknown;
+}
+
+interface GPUComputePipelineLike {
+  getBindGroupLayout(index: number): unknown;
+}
+
+interface GPUDeviceLike {
+  queue: {
+    submit(commands: unknown[]): void;
+    writeBuffer(buffer: GPUBufferLike, bufferOffset: number, data: BufferSource): void;
+  };
+  createBuffer(descriptor: { size: number; usage: number }): GPUBufferLike;
+  createCommandEncoder(): GPUCommandEncoderLike;
+  createBindGroup(descriptor: { layout: unknown; entries: Array<{ binding: number; resource: { buffer: GPUBufferLike } }> }): unknown;
+  createComputePipeline(descriptor: {
+    layout: 'auto';
+    compute: {
+      module: unknown;
+      entryPoint: string;
+    };
+  }): GPUComputePipelineLike;
+  createShaderModule(descriptor: { code: string }): unknown;
+}
+
+interface GPUAdapterLike {
+  features?: {
+    values?(): IterableIterator<unknown>;
+  };
+  limits?: unknown;
+  info?: unknown;
+  requestDevice(): Promise<GPUDeviceLike>;
+}
+
+interface NavigatorWithGpu {
+  gpu?: {
+    requestAdapter(options: { powerPreference: string }): Promise<GPUAdapterLike | null>;
+  };
+}
+
+declare const GPUBufferUsage: {
+  COPY_DST: number;
+  MAP_READ: number;
+  STORAGE: number;
+  COPY_SRC: number;
+  UNIFORM: number;
+};
+declare const GPUMapMode: {
+  READ: number;
+};
 
 const FRAMING_SHADER = `
 struct Params {
@@ -85,7 +146,7 @@ export class LocalSeparatorGpuDsp {
     }
 
     localSeparatorLog('Requesting WebGPU adapter for GPU DSP.');
-    const adapter = await (navigator as { gpu?: { requestAdapter: (options: { powerPreference: string }) => Promise<any> } }).gpu?.requestAdapter({
+    const adapter = await (navigator as NavigatorWithGpu).gpu?.requestAdapter({
       powerPreference: 'high-performance',
     });
     if (!adapter) {