refactor: extract #processFont and #scheduleProcessing from touch and #processQueue

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

@@ -131,26 +131,31 @@ export class AppliedFontsManager {
                 hasNewItems = true;
             }
 
-            // Schedule queue processing if we have new items and no existing timer
             if (hasNewItems && !this.#timeoutId) {
-                // Prefer requestIdleCallback for better performance (waits for browser idle)
+                this.#scheduleProcessing();
-                if (typeof requestIdleCallback !== 'undefined') {
-                    this.#timeoutId = requestIdleCallback(
-                        () => this.#processQueue(),
-                        { timeout: 150 },
-                    ) as unknown as ReturnType<typeof setTimeout>;
-                    this.#pendingType = 'idle';
-                } else {
-                    // Fallback to setTimeout with ~60fps timing
-                    this.#timeoutId = setTimeout(() => this.#processQueue(), 16);
-                    this.#pendingType = 'timeout';
-                }
             }
         } catch (error) {
             console.error(error);
         }
     }
 
+    /**
+     * Schedules `#processQueue()` via `requestIdleCallback` (150ms timeout) when available,
+     * falling back to `setTimeout(16ms)` for ~60fps timing.
+     */
+    #scheduleProcessing(): void {
+        if (typeof requestIdleCallback !== 'undefined') {
+            this.#timeoutId = requestIdleCallback(
+                () => this.#processQueue(),
+                { timeout: 150 },
+            ) as unknown as ReturnType<typeof setTimeout>;
+            this.#pendingType = 'idle';
+        } else {
+            this.#timeoutId = setTimeout(() => this.#processQueue(), 16);
+            this.#pendingType = 'timeout';
+        }
+    }
+
     /** Returns true if data-saver mode is enabled (defers non-critical weights). */
     #shouldDeferNonCritical(): boolean {
         return (navigator as any).connection?.saveData === true;
@@ -229,19 +234,7 @@ export class AppliedFontsManager {
                 continue;
             }
 
-            try {
+            await this.#processFont(key, config, buffer);
-                // Parse buffer into FontFace and register with document
-                const font = await loadFont(config, buffer);
-                this.#loadedFonts.set(key, font);
-                this.#urlByKey.set(key, config.url);
-                this.statuses.set(key, 'loaded');
-            } catch (e) {
-                if (e instanceof FontParseError) {
-                    console.error(`Font parse failed: ${config.name}`, e);
-                    this.statuses.set(key, 'error');
-                    this.#queue.incrementRetry(key);
-                }
-            }
 
             // Yield to main thread if needed (prevents UI blocking)
             // Chromium: use isInputPending() for optimal responsiveness
@@ -257,6 +250,25 @@ export class AppliedFontsManager {
         }
     }
 
+    /**
+     * Parses a fetched buffer into a {@link FontFace}, registers it with `document.fonts`,
+     * and updates reactive status. On failure, sets status to `'error'` and increments the retry count.
+     */
+    async #processFont(key: string, config: FontLoadRequestConfig, buffer: ArrayBuffer): Promise<void> {
+        try {
+            const font = await loadFont(config, buffer);
+            this.#loadedFonts.set(key, font);
+            this.#urlByKey.set(key, config.url);
+            this.statuses.set(key, 'loaded');
+        } catch (e) {
+            if (e instanceof FontParseError) {
+                console.error(`Font parse failed: ${config.name}`, e);
+                this.statuses.set(key, 'error');
+                this.#queue.incrementRetry(key);
+            }
+        }
+    }
+
     /** Removes fonts unused within TTL (LRU-style cleanup). Runs every PURGE_INTERVAL. Pinned fonts are never evicted. */
     #purgeUnused() {
         const now = Date.now();