refactor(typography): lazy getTypographySettingsStore + fix effect leak

Convert the eager typographySettingsStore singleton to getTypographySettingsStore()
(+ __resetTypographySettingsStore for tests) and update barrels and consumers
(TypographyMenu, FontSampler, SampleList, ComparisonView Line/SliderArea,
comparisonStore + its mock).

Fix a latent leak while here: the store ran $effect.root and discarded the
returned cleanup, so its storage-sync effects outlived every instance. Capture
the disposer and expose destroy(), which __reset now calls.

src/features/AdjustTypography/index.ts

@@ -1,9 +1,9 @@
 export {
     createTypographySettingsStore,
+    getTypographySettingsStore,
     MULTIPLIER_L,
     MULTIPLIER_M,
     MULTIPLIER_S,
     type TypographySettingsStore,
-    typographySettingsStore,
 } from './model';
 export { TypographyMenu } from './ui';

src/features/AdjustTypography/model/index.ts

@@ -5,6 +5,6 @@ export {
 } from './const/const';
 export {
     createTypographySettingsStore,
+    getTypographySettingsStore,
     type TypographySettingsStore,
-    typographySettingsStore,
 } from './store/typographySettingsStore/typographySettingsStore.svelte';

src/features/AdjustTypography/model/store/typographySettingsStore/typographySettingsStore.svelte.ts

@@ -94,6 +94,12 @@ export class TypographySettingsStore {
      * The underlying font size before responsive scaling is applied
      */
     #baseSize = $state(DEFAULT_FONT_SIZE);
+    /**
+     * Disposes the $effect.root that backs the storage-sync effects.
+     * $effect.root lives outside component lifecycle, so callers must invoke
+     * destroy() to avoid leaking the subscriptions.
+     */
+    #disposeEffects: () => void;
 
     constructor(configs: ControlModel<ControlId>[], storage: PersistentStore<TypographySettings>) {
         this.#storage = storage;
@@ -117,7 +123,7 @@ export class TypographySettingsStore {
 
         // The Sync Effect (UI -> Storage)
         // We access .value explicitly to ensure Svelte 5 tracks the dependency
-        $effect.root(() => {
+        this.#disposeEffects = $effect.root(() => {
             $effect(() => {
                 // EXPLICIT DEPENDENCIES: Accessing these triggers the effect
                 const fontSize = this.#baseSize;
@@ -155,6 +161,13 @@ export class TypographySettingsStore {
         });
     }
 
+    /**
+     * Tears down the storage-sync effects. Call on unmount / store disposal.
+     */
+    destroy(): void {
+        this.#disposeEffects();
+    }
+
     /**
      * Gets initial value for a control from storage or defaults
      */
@@ -336,10 +349,24 @@ export function createTypographySettingsStore(
     return new TypographySettingsStore(configs, storage);
 }
 
+export type TypographySettingsStoreInstance = ReturnType<typeof createTypographySettingsStore>;
+
+let _typographySettingsStore: TypographySettingsStoreInstance | undefined;
+
 /**
- * App-wide typography settings singleton, keyed for the comparison view.
+ * App-wide typography settings store, keyed for the comparison view.
+ * Created on first access so its persistent-store sync effects aren't set up
+ * at module load.
  */
-export const typographySettingsStore = createTypographySettingsStore(
+export function getTypographySettingsStore(): TypographySettingsStoreInstance {
+    return (_typographySettingsStore ??= createTypographySettingsStore(
         DEFAULT_TYPOGRAPHY_CONTROLS_DATA,
         COMPARISON_STORAGE_KEY,
-);
+    ));
+}
+
+// test-only reset, so specs don't share persisted typography state or leak effects
+export function __resetTypographySettingsStore() {
+    _typographySettingsStore?.destroy();
+    _typographySettingsStore = undefined;
+}

src/features/AdjustTypography/ui/TypographyMenu/TypographyMenu.svelte

@@ -23,7 +23,7 @@ import {
     MULTIPLIER_L,
     MULTIPLIER_M,
     MULTIPLIER_S,
-    typographySettingsStore,
+    getTypographySettingsStore,
 } from '../../model';
 
 interface Props {
@@ -46,6 +46,7 @@ interface Props {
 let { class: className, hidden = false, open = $bindable(false) }: Props = $props();
 
 const responsive = getContext<ResponsiveManager>('responsive');
+const typographySettingsStore = getTypographySettingsStore();
 
 /**
  * Sets the common font size multiplier based on the current responsive state.

src/features/DisplayFont/ui/FontSampler/FontSampler.svelte

@@ -9,7 +9,7 @@ import {
     type FontLoadStatus,
     type UnifiedFont,
 } from '$entities/Font';
-import { typographySettingsStore } from '$features/AdjustTypography/model';
+import { getTypographySettingsStore } from '$features/AdjustTypography/model';
 import {
     Badge,
     ContentEditable,
@@ -43,6 +43,8 @@ interface Props {
 
 let { font, status, text = $bindable(), index = 0 }: Props = $props();
 
+const typographySettingsStore = getTypographySettingsStore();
+
 // Extract provider badge with fallback
 const providerBadge = $derived(
     font.providerBadge

src/widgets/ComparisonView/model/stores/comparisonStore.svelte.ts

@@ -24,7 +24,10 @@ import {
     fontLifecycleManager,
     getFontCatalog,
 } from '$entities/Font/model';
-import { typographySettingsStore } from '$features/AdjustTypography/model';
+import {
+    type TypographySettingsStore,
+    getTypographySettingsStore,
+} from '$features/AdjustTypography/model';
 import { createPersistentStore } from '$shared/lib';
 import { untrack } from 'svelte';
 import { getPretextFontString } from '../../lib';
@@ -101,11 +104,14 @@ export class ComparisonStore {
 
     #fontCatalog: FontCatalogStore;
 
+    #typography: TypographySettingsStore;
+
     constructor() {
         // Synchronously seed the batch store with any IDs already in storage
         const { fontAId, fontBId } = storage.value;
         this.#fontsByIdsStore = new FontsByIdsStore(fontAId && fontBId ? [fontAId, fontBId] : []);
         this.#fontCatalog = getFontCatalog();
+        this.#typography = getTypographySettingsStore();
 
         $effect.root(() => {
             // Sync batch results → fontA / fontB
@@ -134,7 +140,7 @@ export class ComparisonStore {
             $effect(() => {
                 const fa = this.#fontA;
                 const fb = this.#fontB;
-                const weight = typographySettingsStore.weight;
+                const weight = this.#typography.weight;
 
                 if (!fa || !fb) {
                     return;
@@ -195,7 +201,7 @@ export class ComparisonStore {
             $effect(() => {
                 const fa = this.#fontA;
                 const fb = this.#fontB;
-                const w = typographySettingsStore.weight;
+                const w = this.#typography.weight;
                 if (fa) {
                     fontLifecycleManager.pin(fa.id, w, fa.features?.isVariable);
                 }
@@ -226,8 +232,8 @@ export class ComparisonStore {
             return;
         }
 
-        const weight = typographySettingsStore.weight;
+        const weight = this.#typography.weight;
-        const size = typographySettingsStore.renderedSize;
+        const size = this.#typography.renderedSize;
         const fontAName = this.#fontA?.name;
         const fontBName = this.#fontB?.name;
 
@@ -356,7 +362,7 @@ export class ComparisonStore {
         this.#fontB = undefined;
         this.#fontsByIdsStore.setIds([]);
         storage.clear();
-        typographySettingsStore.reset();
+        this.#typography.reset();
     }
 }
 

src/widgets/ComparisonView/model/stores/comparisonStore.test.ts

@@ -89,12 +89,14 @@ vi.mock('$features/AdjustTypography', () => ({
     })),
 }));
 
-vi.mock('$features/AdjustTypography/model', () => ({
+const mockTypography = vi.hoisted(() => ({
-    typographySettingsStore: {
     weight: 400,
     renderedSize: 48,
     reset: vi.fn(),
-    },
+}));
+
+vi.mock('$features/AdjustTypography/model', () => ({
+    getTypographySettingsStore: () => mockTypography,
 }));
 
 import * as proxyFonts from '$entities/Font/api/proxy/proxyFonts';

src/widgets/ComparisonView/ui/Line/Line.svelte

@@ -11,7 +11,7 @@ import {
     type ComparisonLine,
     computeLineRenderModel,
 } from '$entities/Font';
-import { typographySettingsStore } from '$features/AdjustTypography';
+import { getTypographySettingsStore } from '$features/AdjustTypography';
 import { getComparisonStore } from '../../model';
 import Character from '../Character/Character.svelte';
 
@@ -36,7 +36,7 @@ const comparisonStore = getComparisonStore();
 
 const model = $derived(computeLineRenderModel(line, split, windowSize));
 
-const typography = $derived(typographySettingsStore);
+const typography = getTypographySettingsStore();
 const fontA = $derived(comparisonStore.fontA);
 const fontB = $derived(comparisonStore.fontB);
 

src/widgets/ComparisonView/ui/SliderArea/SliderArea.svelte

@@ -18,7 +18,7 @@ import {
     MULTIPLIER_M,
     MULTIPLIER_S,
     TypographyMenu,
-    typographySettingsStore,
+    getTypographySettingsStore,
 } from '$features/AdjustTypography';
 import {
     type ResponsiveManager,
@@ -81,7 +81,7 @@ const SLIDER_STEP_COARSE = 10;
 const fontA = $derived(comparisonStore.fontA);
 const fontB = $derived(comparisonStore.fontB);
 const isLoading = $derived(comparisonStore.isLoading || !comparisonStore.isReady);
-const typography = $derived(typographySettingsStore);
+const typography = getTypographySettingsStore();
 
 let container = $state<HTMLElement>();
 

src/widgets/SampleList/ui/SampleList/SampleList.svelte

@@ -15,7 +15,7 @@ import {
 } from '$entities/Font/model';
 import {
     TypographyMenu,
-    typographySettingsStore,
+    getTypographySettingsStore,
 } from '$features/AdjustTypography';
 import { FontSampler } from '$features/DisplayFont';
 import { throttle } from '$shared/lib/utils';
@@ -23,6 +23,7 @@ import { Skeleton } from '$shared/ui';
 import { layoutManager } from '../../model';
 
 const fontCatalog = getFontCatalog();
+const typographySettingsStore = getTypographySettingsStore();
 
 // FontSampler chrome heights — derived from Tailwind classes in FontSampler.svelte.
 // Header: py-3 (12+12px padding) + ~32px content row ≈ 56px.