fix: long track name displaying issue; wrong separator model name mapping; imported generated full song not adjusting max bars; implemented retry mechanism for K.G.One server calls.

src/util/retryUtil.ts

@@ -0,0 +1,56 @@
+import { KGONE_CONSTANTS } from '../constants/coreConstants';
+
+export interface RetryConfig {
+  maxAttempts?: number;
+  initialDelayMs?: number;
+  backoffMultiplier?: number;
+}
+
+/**
+ * Wraps fetch() with exponential-backoff retry on non-200 responses or
+ * network errors. AbortErrors propagate immediately — no retry.
+ *
+ * Use only for idempotent calls (polling, downloads).
+ * Do NOT use for load-model or job-submission calls.
+ */
+export async function fetchWithRetry(
+  url: string,
+  options: RequestInit,
+  config: RetryConfig = {}
+): Promise<Response> {
+  const {
+    maxAttempts      = KGONE_CONSTANTS.MAX_RETRY_ATTEMPTS,
+    initialDelayMs   = KGONE_CONSTANTS.RETRY_INITIAL_DELAY_MS,
+    backoffMultiplier = KGONE_CONSTANTS.RETRY_BACKOFF_MULTIPLIER,
+  } = config;
+
+  const signal = options.signal as AbortSignal | undefined;
+  let delay = initialDelayMs;
+  let lastError: Error = new Error('Unknown error');
+
+  for (let attempt = 0; attempt < maxAttempts; attempt++) {
+    try {
+      const resp = await fetch(url, options);
+      if (resp.ok) return resp;
+
+      const body = await resp.text().catch(() => '');
+      lastError = new Error(`HTTP ${resp.status}${body ? `: ${body}` : ''}`);
+    } catch (err) {
+      // Propagate abort immediately — user cancelled, do not retry
+      if (err instanceof DOMException && err.name === 'AbortError') throw err;
+      lastError = err instanceof Error ? err : new Error(String(err));
+    }
+
+    if (attempt < maxAttempts - 1) {
+      // Abort-aware sleep before the next attempt
+      await new Promise<void>(resolve => {
+        const t = setTimeout(resolve, delay);
+        signal?.addEventListener('abort', () => { clearTimeout(t); resolve(); }, { once: true });
+      });
+      if (signal?.aborted) throw new DOMException('Aborted', 'AbortError');
+      delay *= backoffMultiplier;
+    }
+  }
+
+  throw lastError;
+}