src/features/GetFonts/model/index.ts

@@ -17,7 +17,7 @@ export {
      * Low-level property selection store
      */
     filtersStore,
-} from './store/filters.svelte';
+} from './store/filters/filters.svelte';
 
 /**
  * Main filter controller
@@ -67,4 +67,4 @@ export {
      * Reactive store for the current sort selection
      */
     sortStore,
-} from './store/sortStore.svelte';
+} from './store/sortStore/sortStore.svelte';

src/features/GetFonts/model/store/bindings.svelte.ts

@@ -13,8 +13,8 @@ import { fontStore } from '$entities/Font';
 import { untrack } from 'svelte';
 import { mapManagerToParams } from '../../lib/mapper/mapManagerToParams';
 import { filterManager } from './filterManager/filterManager.svelte';
-import { filtersStore } from './filters.svelte';
+import { filtersStore } from './filters/filters.svelte';
-import { sortStore } from './sortStore.svelte';
+import { sortStore } from './sortStore/sortStore.svelte';
 
 $effect.root(() => {
     /**

src/features/GetFonts/model/store/filters/filters.svelte.ts

@@ -31,7 +31,7 @@ import {
  * Fetches and caches filter metadata using fetchProxyFilters()
  * Provides reactive access to filter data
  */
-class FiltersStore {
+export class FiltersStore {
     /**
      * TanStack Query result state
      */

src/features/GetFonts/model/store/filters/filters.test.ts

@@ -0,0 +1,116 @@
+import { queryClient } from '$shared/api/queryClient';
+import {
+    afterEach,
+    beforeEach,
+    describe,
+    expect,
+    it,
+    vi,
+} from 'vitest';
+import * as filtersApi from '../../../api/filters/filters';
+import type { FilterMetadata } from '../../../api/filters/filters';
+import { FiltersStore } from './filters.svelte';
+
+/**
+ * Build a minimal FilterMetadata fixture for tests.
+ */
+function metadata(id: string, optionValues: string[] = []): FilterMetadata {
+    return {
+        id,
+        name: id,
+        description: '',
+        type: 'enum',
+        options: optionValues.map(value => ({
+            id: value,
+            name: value,
+            value,
+            count: 1,
+        })),
+    } as FilterMetadata;
+}
+
+describe('FiltersStore', () => {
+    let store: FiltersStore;
+
+    beforeEach(() => {
+        queryClient.clear();
+        // TanStack defaults retry=3 with exponential backoff, which would
+        // make the error-path test wait >5s. Disable for deterministic timing.
+        queryClient.setDefaultOptions({ queries: { retry: false } });
+        vi.clearAllMocks();
+    });
+
+    afterEach(() => {
+        store?.destroy();
+    });
+
+    describe('initial state', () => {
+        it('starts with an empty filter list', () => {
+            vi.spyOn(filtersApi, 'fetchProxyFilters').mockResolvedValue([]);
+            store = new FiltersStore();
+            expect(store.filters).toEqual([]);
+        });
+
+        it('reports null error before any failure', () => {
+            vi.spyOn(filtersApi, 'fetchProxyFilters').mockResolvedValue([]);
+            store = new FiltersStore();
+            expect(store.error).toBeNull();
+        });
+    });
+
+    describe('successful fetch', () => {
+        it('populates filters with the fetched metadata', async () => {
+            const data = [
+                metadata('providers', ['google', 'fontshare']),
+                metadata('categories', ['serif', 'sans-serif']),
+            ];
+            vi.spyOn(filtersApi, 'fetchProxyFilters').mockResolvedValue(data);
+
+            store = new FiltersStore();
+
+            await vi.waitFor(() => expect(store.filters).toEqual(data), { timeout: 1000 });
+            expect(store.isError).toBe(false);
+            expect(store.error).toBeNull();
+        });
+
+        it('calls fetchProxyFilters exactly once for the initial load', async () => {
+            const spy = vi.spyOn(filtersApi, 'fetchProxyFilters').mockResolvedValue([]);
+            store = new FiltersStore();
+
+            await vi.waitFor(() => expect(spy).toHaveBeenCalledTimes(1), { timeout: 1000 });
+        });
+    });
+
+    describe('error handling', () => {
+        it('flips isError and exposes the error message on fetch failure', async () => {
+            vi.spyOn(filtersApi, 'fetchProxyFilters').mockRejectedValue(new Error('boom'));
+            store = new FiltersStore();
+
+            await vi.waitFor(() => expect(store.isError).toBe(true), { timeout: 1000 });
+            expect(store.error).toBe('boom');
+            expect(store.filters).toEqual([]);
+        });
+    });
+
+    describe('caching', () => {
+        it('does not trigger a second fetch when another instance shares the query key', async () => {
+            const data = [metadata('providers', ['google'])];
+            const spy = vi.spyOn(filtersApi, 'fetchProxyFilters').mockResolvedValue(data);
+
+            store = new FiltersStore();
+            await vi.waitFor(() => expect(store.filters).toEqual(data), { timeout: 1000 });
+            expect(spy).toHaveBeenCalledTimes(1);
+
+            // A second observer on the same query key should reuse the cached
+            // result rather than triggering a new request.
+            const second = new FiltersStore();
+            try {
+                // Give the new observer a tick to potentially refetch (it shouldn't).
+                await new Promise(r => setTimeout(r, 50));
+                expect(spy).toHaveBeenCalledTimes(1);
+            } finally {
+                second.destroy();
+            }
+        });
+    });
+});

src/features/GetFonts/model/store/sortStore/sortStore.svelte.ts

@@ -17,7 +17,7 @@ export const SORT_MAP: Record<SortOption, 'name' | 'popularity' | 'lastModified'
 
 export type SortApiValue = (typeof SORT_MAP)[SortOption];
 
-function createSortStore(initial: SortOption = 'Popularity') {
+export function createSortStore(initial: SortOption = 'Popularity') {
     let current = $state<SortOption>(initial);
 
     return {

src/features/GetFonts/model/store/sortStore/sortStore.test.ts

@@ -0,0 +1,68 @@
+import {
+    describe,
+    expect,
+    it,
+} from 'vitest';
+import {
+    SORT_MAP,
+    SORT_OPTIONS,
+    type SortOption,
+    createSortStore,
+    sortStore,
+} from './sortStore.svelte';
+
+describe('createSortStore', () => {
+    describe('initialization', () => {
+        it('defaults to Popularity when no initial value is provided', () => {
+            const store = createSortStore();
+            expect(store.value).toBe('Popularity');
+        });
+
+        it('accepts an explicit initial value', () => {
+            const store = createSortStore('Newest');
+            expect(store.value).toBe('Newest');
+        });
+    });
+
+    describe('apiValue mapping', () => {
+        it.each<[SortOption, (typeof SORT_MAP)[SortOption]]>([
+            ['Name', 'name'],
+            ['Popularity', 'popularity'],
+            ['Newest', 'lastModified'],
+        ])('maps %s to %s', (display, api) => {
+            const store = createSortStore(display);
+            expect(store.apiValue).toBe(api);
+        });
+    });
+
+    describe('set()', () => {
+        it('updates both value and apiValue together', () => {
+            const store = createSortStore('Name');
+            store.set('Newest');
+            expect(store.value).toBe('Newest');
+            expect(store.apiValue).toBe('lastModified');
+        });
+
+        it('is idempotent — setting the current value keeps state consistent', () => {
+            const store = createSortStore('Popularity');
+            store.set('Popularity');
+            expect(store.value).toBe('Popularity');
+        });
+    });
+});
+
+describe('sortStore singleton', () => {
+    it('exposes the same shape as a factory instance', () => {
+        expect(typeof sortStore.value).toBe('string');
+        expect(typeof sortStore.apiValue).toBe('string');
+        expect(typeof sortStore.set).toBe('function');
+    });
+
+    it('accepts all SORT_OPTIONS as valid set() inputs', () => {
+        for (const option of SORT_OPTIONS) {
+            sortStore.set(option);
+            expect(sortStore.value).toBe(option);
+            expect(sortStore.apiValue).toBe(SORT_MAP[option]);
+        }
+    });
+});