feat(sync): add Octokit retry/throttle and rate-limited status

packages/backend/tests/unit/rate-limit.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, test } from 'vitest';
+
+import { isRateLimitError } from '../../convex/githubClient';
+
+describe('isRateLimitError', () => {
+  test('detects a 403 primary rate limit via ratelimit-remaining header', () => {
+    expect(
+      isRateLimitError({
+        status: 403,
+        response: { headers: { 'x-ratelimit-remaining': '0' } },
+      }),
+    ).toBe(true);
+  });
+
+  test('detects a 429 status', () => {
+    expect(isRateLimitError({ status: 429 })).toBe(true);
+  });
+
+  test('detects a secondary rate limit via message', () => {
+    expect(
+      isRateLimitError({ status: 403, message: 'secondary rate limit' }),
+    ).toBe(true);
+  });
+
+  test('returns false for a 404', () => {
+    expect(isRateLimitError({ status: 404 })).toBe(false);
+  });
+
+  test('returns false for a 500', () => {
+    expect(isRateLimitError({ status: 500 })).toBe(false);
+  });
+
+  test('returns false for a generic Error', () => {
+    expect(isRateLimitError(new Error('boom'))).toBe(false);
+  });
+
+  test('returns false for non-object values', () => {
+    expect(isRateLimitError(null)).toBe(false);
+    expect(isRateLimitError(undefined)).toBe(false);
+    expect(isRateLimitError('rate limit')).toBe(false);
+  });
+});