feat(appliedFontsStore): improvement that allow to use correct urls for variable fonts and fixes font weight problems

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

@@ -52,16 +52,27 @@ class AppliedFontsManager {
         }
     }
 
-    #getFontKey(id: string, weight: number): string {
-        return `${id.toLowerCase()}@${weight}`;
+    #getFontKey(config: FontConfigRequest): string {
+        if (config.isVariable) {
+            // For variable fonts, the ID is unique enough.
+            // Loading "Roboto" once covers "Roboto 400" and "Roboto 700"
+            return `${config.id.toLowerCase()}@vf`;
+        }
+        // For static fonts, we still need weight separation
+        return `${config.id.toLowerCase()}@${config.weight}`;
     }
 
     touch(configs: FontConfigRequest[]) {
         const now = Date.now();
         configs.forEach(config => {
-            const key = this.#getFontKey(config.id, config.weight);
+            // Pass the whole config to get key
+            const key = this.#getFontKey(config);
+
             this.#usageTracker.set(key, now);
 
+            // If it's already loaded, we don't need to do anything
+            if (this.statuses.get(key) === 'loaded') return;
+
             if (!this.#idToBatch.has(key) && !this.#queue.has(key)) {
                 this.#queue.set(key, config);
 
@@ -71,8 +82,10 @@ class AppliedFontsManager {
         });
     }
 
-    getFontStatus(id: string, weight: number) {
-        return this.statuses.get(this.#getFontKey(id, weight));
+    getFontStatus(id: string, weight: number, isVariable: boolean = false) {
+        // Construct a temp config to generate key
+        const key = this.#getFontKey({ id, weight, name: '', url: '', isVariable });
+        return this.statuses.get(key);
     }
 
     #processQueue() {
@@ -97,27 +110,31 @@ class AppliedFontsManager {
             this.statuses.set(key, 'loading');
             this.#idToBatch.set(key, batchId);
 
-            // Construct the @font-face rule
-            // Using format('truetype') for .ttf
+            // If variable, allow the full weight range.
+            // If static, lock it to the specific weight.
+            const weightRule = config.isVariable
+                ? '100 900' // Variable range (standard coverage)
+                : config.weight;
+            const fontFormat = config.isVariable ? 'truetype-variations' : 'truetype';
+
             cssRules += `
-                @font-face {
-                    font-family: '${config.name}';
-                    src: url('${config.url}') format('truetype');
-                    font-weight: ${config.weight};
-                    font-style: normal;
-                    font-display: swap;
-                }
-            `;
+                    @font-face {
+                        font-family: '${config.name}';
+                        src: url('${config.url}') format('${fontFormat}');
+                        font-weight: ${weightRule};
+                        font-style: normal;
+                        font-display: swap;
+                    }
+                `;
         });
 
-        // Create and inject the style tag
         const style = document.createElement('style');
         style.dataset.batchId = batchId;
         style.innerHTML = cssRules;
         document.head.appendChild(style);
         this.#batchElements.set(batchId, style);
 
-        // Verify loading via Font Loading API
+        // Use the requested weight for verification, even if the rule covers a range
         batchEntries.forEach(([key, config]) => {
             document.fonts.load(`${config.weight} 1em "${config.name}"`)
                 .then(loaded => {
@@ -126,7 +143,6 @@ class AppliedFontsManager {
                 .catch(() => this.statuses.set(key, 'error'));
         });
     }
-
     #purgeUnused() {
         const now = Date.now();
         const batchesToRemove = new Set<string>();

src/entities/Font/ui/FontApplicator/FontApplicator.svelte

@@ -26,6 +26,8 @@ interface Props {
      * Font weight
      */
     weight?: number;
+
+    isVariable?: boolean;
     /**
      * Additional classes
      */
@@ -36,27 +38,42 @@ interface Props {
     children?: Snippet;
 }
 
-let { name, id, url, weight = 400, className, children }: Props = $props();
+let { name, id, url, weight = 400, isVariable = false, className, children }: Props = $props();
 let element: Element;
 
 // Track if the user has actually scrolled this into view
 let hasEnteredViewport = $state(false);
+const status = $derived(appliedFontsManager.getFontStatus(id, weight, isVariable));
 
 $effect(() => {
+    if (status === 'loaded' || status === 'error') {
+        hasEnteredViewport = true;
+        return;
+    }
+
     const observer = new IntersectionObserver(entries => {
         if (entries[0].isIntersecting) {
             hasEnteredViewport = true;
-            appliedFontsManager.touch([{ id, weight, name, url }]);
 
-            // Once it has entered, we can stop observing to save CPU
+            // Touch ensures it's in the queue.
+            // It's safe to call this even if VirtualList called it
+            // (Manager dedupes based on key)
+            appliedFontsManager.touch([{
+                id,
+                weight,
+                name,
+                url,
+                isVariable,
+            }]);
+
             observer.unobserve(element);
         }
     });
-    observer.observe(element);
+
+    if (element) observer.observe(element);
     return () => observer.disconnect();
 });
 
-const status = $derived(appliedFontsManager.getFontStatus(id, weight));
 // The "Show" condition: Element is in view AND (Font is ready OR it errored out)
 const shouldReveal = $derived(hasEnteredViewport && (status === 'loaded' || status === 'error'));
 
@@ -69,7 +86,7 @@ const transitionClasses = $derived(
 
 <div
     bind:this={element}
-    style:font-family={name}
+    style:font-family={shouldReveal ? `'${name}'` : 'sans-serif'}
     class={cn(
         transitionClasses,
         // If reduced motion is on, we skip the transform/blur entirely

src/entities/Font/ui/FontVirtualList/FontVirtualList.svelte

@@ -4,9 +4,10 @@
     - Handles font registration with the manager
 -->
 <script lang="ts" generics="T extends UnifiedFont">
-import type { FontConfigRequest } from '$entities/Font/model/store/appliedFontsStore/appliedFontsStore.svelte';
 import { VirtualList } from '$shared/ui';
 import type { ComponentProps } from 'svelte';
+import { getFontUrl } from '../../lib';
+import type { FontConfigRequest } from '../../model';
 import {
     type UnifiedFont,
     appliedFontsManager,
@@ -21,16 +22,25 @@ interface Props extends Omit<ComponentProps<typeof VirtualList<T>>, 'onVisibleIt
 let { items, children, onVisibleItemsChange, onNearBottom, weight, ...rest }: Props = $props();
 
 function handleInternalVisibleChange(visibleItems: T[]) {
+    const configs: FontConfigRequest[] = [];
+
+    visibleItems.forEach(item => {
+        const url = getFontUrl(item, weight);
+
+        if (url) {
+            configs.push({
+                id: item.id,
+                name: item.name,
+                weight,
+                url,
+                isVariable: item.features?.isVariable,
+            });
+        }
+    });
     // Auto-register fonts with the manager
-    const configs = visibleItems.map<FontConfigRequest>(item => ({
-        id: item.id,
-        name: item.name,
-        weight,
-        url: item.styles.regular!,
-    }));
     appliedFontsManager.touch(configs);
 
-    // // Forward the call to any external listener
+    // Forward the call to any external listener
     // onVisibleItemsChange?.(visibleItems);
 }