feat(fonts): implement Phase 2 - Unified Font Store

- Implemented UnifiedFontStore extending BaseFontStore
- Added pagination support with derived metadata
- Added provider-specific shortcuts (setProvider, setCategory, etc.)
- Added pagination methods (nextPage, prevPage, goToPage)
- Added category getter shortcuts (sansSerifFonts, serifFonts, etc.)
- Updated store exports to include unified store
- Fixed typo in googleFontsStore.svelte.ts (createGoogleFontsStore)

Phase 2/7: Proxy API Integration for GlyphDiff

src/entities/Font/model/store/googleFontsStore.svelte.ts

@@ -20,7 +20,7 @@ export class GoogleFontsStore extends BaseFontStore<GoogleFontsParams> {
     }
 }
 
-export function createFontshareStore(params: GoogleFontsParams = {}) {
+export function createGoogleFontsStore(params: GoogleFontsParams = {}) {
     return new GoogleFontsStore(params);
 }
 

src/entities/Font/model/store/index.ts

@@ -6,18 +6,29 @@
  * Single export point for the unified font store infrastructure.
  */
 
-// export {
-//     createUnifiedFontStore,
-//     UNIFIED_FONT_STORE_KEY,
-//     type UnifiedFontStore,
-// } from './unifiedFontStore.svelte';
+// Primary store (unified)
+export {
+    createUnifiedFontStore,
+    type UnifiedFontStore,
+    unifiedFontStore,
+} from './unifiedFontStore.svelte';
 
+// Applied fonts manager (CSS loading - unchanged)
+export { appliedFontsManager } from './appliedFontsStore/appliedFontsStore.svelte';
+
+// Selected fonts store (user selection - unchanged)
+export { selectedFontsStore } from './selectedFontsStore/selectedFontsStore.svelte';
+
+// DEPRECATED: Fontshare store (will be removed in Phase 6)
 export {
     createFontshareStore,
     type FontshareStore,
     fontshareStore,
 } from './fontshareStore.svelte';
 
-export { appliedFontsManager } from './appliedFontsStore/appliedFontsStore.svelte';
-
-export { selectedFontsStore } from './selectedFontsStore/selectedFontsStore.svelte';
+// DEPRECATED: Google Fonts store (will be removed in Phase 6)
+export {
+    createGoogleFontsStore,
+    type GoogleFontsStore,
+    googleFontsStore,
+} from './googleFontsStore.svelte';

src/entities/Font/model/store/unifiedFontStore.svelte.ts

@@ -1,25 +1,275 @@
-import { type Filter } from '$shared/lib';
-import { SvelteMap } from 'svelte/reactivity';
-import type { FontProvider } from '../types';
-import type { CheckboxFilter } from '../types/common';
-import type { BaseFontStore } from './baseFontStore.svelte';
-import { createFontshareStore } from './fontshareStore.svelte';
-import type { ProviderParams } from './types';
+/**
+ * Unified font store
+ *
+ * Single source of truth for font data, powered by the proxy API.
+ * Extends BaseFontStore for TanStack Query integration and reactivity.
+ *
+ * Key features:
+ * - Provider-agnostic (proxy API handles provider logic)
+ * - Reactive to filter changes
+ * - Optimistic updates via TanStack Query
+ * - Pagination support
+ * - Provider-specific shortcuts for common operations
+ */
 
-export class UnitedFontStore {
-    private sources: Partial<Record<FontProvider, BaseFontStore<ProviderParams>>>;
+import type { ProxyFontsParams } from '../../api';
+import { fetchProxyFonts } from '../../api';
+import type { UnifiedFont } from '../types';
+import type { FontCategory } from '../types';
+import { BaseFontStore } from './baseFontStore.svelte';
 
-    filters: SvelteMap<CheckboxFilter, Filter>;
-    queryValue = $state('');
+/**
+ * Unified font store wrapping TanStack Query with Svelte 5 runes
+ *
+ * Extends BaseFontStore to provide:
+ * - Reactive state management
+ * - TanStack Query integration for caching
+ * - Dynamic parameter binding for filters
+ * - Pagination support
+ *
+ * @example
+ * ```ts
+ * const store = new UnifiedFontStore({
+ *     provider: 'google',
+ *     category: 'sans-serif',
+ *     limit: 50
+ * });
+ *
+ * // Access reactive state
+ * $effect(() => {
+ *     console.log(store.fonts);
+ *     console.log(store.isLoading);
+ *     console.log(store.pagination);
+ * });
+ *
+ * // Update parameters
+ * store.setCategory('serif');
+ * store.nextPage();
+ * ```
+ */
+export class UnifiedFontStore extends BaseFontStore<ProxyFontsParams> {
+    /**
+     * Store pagination metadata separately from fonts
+     * This is a workaround for TanStack Query's type system
+     */
+    #paginationMetadata = $state<
+        {
+            total: number;
+            limit: number;
+            offset: number;
+        } | null
+    >(null);
 
-    constructor(initialConfig: Partial<Record<FontProvider, ProviderParams>> = {}) {
-        this.sources = {
-            fontshare: createFontshareStore(initialConfig?.fontshare),
+    /**
+     * Pagination metadata (derived from proxy API response)
+     */
+    readonly pagination = $derived.by(() => {
+        if (this.#paginationMetadata) {
+            const { total, limit, offset } = this.#paginationMetadata;
+            return {
+                total,
+                limit,
+                offset,
+                hasMore: offset + limit < total,
+                page: Math.floor(offset / limit) + 1,
+                totalPages: Math.ceil(total / limit),
             };
-        this.filters = new SvelteMap();
+        }
+        return {
+            total: 0,
+            limit: this.params.limit || 50,
+            offset: this.params.offset || 0,
+            hasMore: false,
+            page: 1,
+            totalPages: 0,
+        };
+    });
+
+    constructor(initialParams: ProxyFontsParams = {}) {
+        super(initialParams);
     }
 
-    get fonts() {
-        return Object.values(this.sources).map(store => store.fonts).flat();
+    /**
+     * Query key for TanStack Query caching
+     * Normalizes params to treat empty arrays/strings as undefined
+     */
+    protected getQueryKey(params: ProxyFontsParams) {
+        // Normalize params to treat empty arrays/strings as undefined
+        const normalized = Object.entries(params).reduce((acc, [key, value]) => {
+            if (value === '' || (Array.isArray(value) && value.length === 0)) {
+                return acc;
+            }
+            return { ...acc, [key]: value };
+        }, {});
+
+        return ['unifiedFonts', normalized] as const;
+    }
+
+    /**
+     * Fetch function that calls the proxy API
+     * Returns the full response including pagination metadata
+     */
+    protected async fetchFn(params: ProxyFontsParams): Promise<UnifiedFont[]> {
+        const response = await fetchProxyFonts(params);
+
+        // Store pagination metadata separately for derived values
+        this.#paginationMetadata = {
+            total: response.total,
+            limit: response.limit,
+            offset: response.offset,
+        };
+
+        return response.fonts;
+    }
+
+    // --- Getters (proxied from BaseFontStore) ---
+
+    /**
+     * Get all fonts from current query result
+     */
+    get fonts(): UnifiedFont[] {
+        // The result.data is UnifiedFont[] (from TanStack Query)
+        return (this.result.data as UnifiedFont[] | undefined) ?? [];
+    }
+
+    /**
+     * Check if loading initial data
+     */
+    get isLoading(): boolean {
+        return this.result.isLoading;
+    }
+
+    /**
+     * Check if fetching (including background refetches)
+     */
+    get isFetching(): boolean {
+        return this.result.isFetching;
+    }
+
+    /**
+     * Check if error occurred
+     */
+    get isError(): boolean {
+        return this.result.isError;
+    }
+
+    /**
+     * Check if result is empty (not loading and no fonts)
+     */
+    get isEmpty(): boolean {
+        return !this.isLoading && this.fonts.length === 0;
+    }
+
+    // --- Provider-specific shortcuts ---
+
+    /**
+     * Set provider filter
+     */
+    setProvider(provider: 'google' | 'fontshare' | undefined) {
+        this.setParams({ provider });
+    }
+
+    /**
+     * Set category filter
+     */
+    setCategory(category: ProxyFontsParams['category']) {
+        this.setParams({ category });
+    }
+
+    /**
+     * Set subset filter
+     */
+    setSubset(subset: ProxyFontsParams['subset']) {
+        this.setParams({ subset });
+    }
+
+    /**
+     * Set search query
+     */
+    setSearch(search: string) {
+        this.setParams({ q: search || undefined });
+    }
+
+    /**
+     * Set sort order
+     */
+    setSort(sort: ProxyFontsParams['sort']) {
+        this.setParams({ sort });
+    }
+
+    // --- Pagination methods ---
+
+    /**
+     * Go to next page
+     */
+    nextPage() {
+        if (this.pagination.hasMore) {
+            this.setParams({
+                offset: this.pagination.offset + this.pagination.limit,
+            });
+        }
+    }
+
+    /**
+     * Go to previous page
+     */
+    prevPage() {
+        if (this.pagination.page > 1) {
+            this.setParams({
+                offset: this.pagination.offset - this.pagination.limit,
+            });
+        }
+    }
+
+    /**
+     * Go to specific page
+     */
+    goToPage(page: number) {
+        if (page >= 1 && page <= this.pagination.totalPages) {
+            this.setParams({
+                offset: (page - 1) * this.pagination.limit,
+            });
+        }
+    }
+
+    /**
+     * Set limit (items per page)
+     */
+    setLimit(limit: number) {
+        this.setParams({ limit });
+    }
+
+    // --- Category shortcuts (for convenience) ---
+
+    get sansSerifFonts() {
+        return this.fonts.filter(f => f.category === 'sans-serif');
+    }
+
+    get serifFonts() {
+        return this.fonts.filter(f => f.category === 'serif');
+    }
+
+    get displayFonts() {
+        return this.fonts.filter(f => f.category === 'display');
+    }
+
+    get handwritingFonts() {
+        return this.fonts.filter(f => f.category === 'handwriting');
+    }
+
+    get monospaceFonts() {
+        return this.fonts.filter(f => f.category === 'monospace');
     }
 }
+
+/**
+ * Factory function to create unified font store
+ */
+export function createUnifiedFontStore(params: ProxyFontsParams = {}) {
+    return new UnifiedFontStore(params);
+}
+
+/**
+ * Singleton instance for global use
+ */
+export const unifiedFontStore = new UnifiedFontStore();