Add retrying. Improve diff format

utils/retry.ts

@@ -0,0 +1,47 @@
+import { log } from "./cli.ts";
+
+export type RetryOptions = {
+  maxAttempts?: number;
+  delayMs?: number;
+  shouldRetry?: (error: unknown) => boolean;
+  label?: string;
+};
+
+const defaultShouldRetry = (error: unknown): boolean => {
+  if (!(error instanceof Error)) return false;
+  // retry on transient network errors
+  return (
+    error.name === "AbortError" ||
+    error.message.includes("fetch failed") ||
+    error.message.includes("ECONNRESET") ||
+    error.message.includes("ETIMEDOUT")
+  );
+};
+
+export async function retry<T>(fn: () => Promise<T>, options: RetryOptions = {}): Promise<T> {
+  const maxAttempts = options.maxAttempts ?? 3;
+  const delayMs = options.delayMs ?? 1000;
+  const shouldRetry = options.shouldRetry ?? defaultShouldRetry;
+  const label = options.label ?? "operation";
+
+  let lastError: unknown;
+
+  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
+    try {
+      return await fn();
+    } catch (error) {
+      lastError = error;
+
+      if (attempt === maxAttempts || !shouldRetry(error)) {
+        throw error;
+      }
+
+      const delay = delayMs * attempt;
+      log.warning(`» ${label} failed (attempt ${attempt}/${maxAttempts}), retrying in ${delay}ms...`);
+      await new Promise((resolve) => setTimeout(resolve, delay));
+    }
+  }
+
+  throw lastError;
+}
+