feat: implement stability fixes and enhance error handling

src/lib/antigravity/retry-utils.ts

@@ -0,0 +1,49 @@
+/** Jitter factor: ±20% */
+const JITTER_FACTOR = 0.2;
+
+/** Maximum retry delay in milliseconds (30 seconds) */
+const MAX_DELAY_MS = 30000;
+
+/**
+ * Apply jitter to a delay value to prevent thundering herd
+ * Returns delay ± JITTER_FACTOR (e.g., 1000ms ± 20% = 800-1200ms)
+ *
+ * @param delayMs - Base delay in milliseconds
+ * @returns Jittered delay (minimum 1ms)
+ */
+export function applyJitter(delayMs: number): number {
+  if (delayMs <= 0) {
+    return 1;
+  }
+
+  const jitterRange = delayMs * JITTER_FACTOR;
+  const jitter = (Math.random() * 2 - 1) * jitterRange;
+  return Math.max(1, Math.round(delayMs + jitter));
+}
+
+/**
+ * Calculate retry delay with exponential backoff and jitter
+ *
+ * @param attempt - Current attempt number (0-indexed)
+ * @param baseMs - Base delay for first retry (default 1000ms)
+ * @returns Delay in milliseconds with jitter applied
+ */
+export function calculateRetryDelay(attempt: number, baseMs: number = 1000): number {
+  // Exponential backoff: 1s, 2s, 4s, 8s, ...
+  const exponentialDelay = baseMs * Math.pow(2, attempt);
+
+  // Cap at maximum delay
+  const cappedDelay = Math.min(exponentialDelay, MAX_DELAY_MS);
+
+  // Apply jitter
+  return applyJitter(cappedDelay);
+}
+
+/**
+ * Sleep for specified milliseconds
+ *
+ * @param ms - Milliseconds to sleep
+ */
+export function sleep(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}