Make 400-retry integration tests deterministic (retry-then-succeed)

Addresses Copilot review: the timing-based calls>1 assertion could be flaky on
slow CI. Now the stub returns a transient 400 twice then a 200, so the retry count
is exact regardless of scheduling.

Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>

tests/test_retries.py

@@ -21,9 +21,11 @@ def response(status_code, json_body=None):
 
 
 def fast_retries():
-    # Tiny, jitter-free budget so retry() exhausts in milliseconds during tests.
+    # Jitter-free, 1ms intervals. Budget is generous so these tests terminate on
+    # success / non-retryable status rather than on the elapsed-time timeout, which
+    # keeps `calls` counts deterministic regardless of CI scheduling overhead.
     backoff = BackoffStrategy(
-        initial_interval=1, max_interval=1, exponent=1.0, max_elapsed_time=20, jitter_ms=0
+        initial_interval=1, max_interval=1, exponent=1.0, max_elapsed_time=10000, jitter_ms=0
     )
     return Retries(RetryConfig("backoff", backoff, retry_connection_errors=True), ["5XX"])
 
@@ -46,17 +48,19 @@ class WrapsTransientInnerCodeTests(unittest.TestCase):
 
 
 class RetryIntegrationTests(unittest.TestCase):
-    def test_retries_400_wrapping_transient_code(self):
+    def test_retries_400_wrapping_transient_code_then_succeeds(self):
         calls = 0
 
         def func():
             nonlocal calls
             calls += 1
-            return response(400, {"error": {"message": "Provider returned error", "code": 502}})
+            if calls < 3:
+                return response(400, {"error": {"message": "Provider returned error", "code": 502}})
+            return response(200, {"ok": True})
 
         result = retry(func, fast_retries())
-        self.assertEqual(result.status_code, 400)
+        self.assertEqual(result.status_code, 200)
-        self.assertGreater(calls, 1)  # it retried
+        self.assertEqual(calls, 3)  # retried twice, then succeeded
 
     def test_does_not_retry_plain_400(self):
         calls = 0
@@ -70,17 +74,19 @@ class RetryIntegrationTests(unittest.TestCase):
         self.assertEqual(result.status_code, 400)
         self.assertEqual(calls, 1)  # not retried
 
-    def test_async_retries_400_wrapping_transient_code(self):
+    def test_async_retries_400_wrapping_transient_code_then_succeeds(self):
         calls = 0
 
         async def func():
             nonlocal calls
             calls += 1
-            return response(400, {"error": {"code": 503}})
+            if calls < 3:
+                return response(400, {"error": {"code": 503}})
+            return response(200, {"ok": True})
 
         result = asyncio.run(retry_async(func, fast_retries()))
-        self.assertEqual(result.status_code, 400)
+        self.assertEqual(result.status_code, 200)
-        self.assertGreater(calls, 1)
+        self.assertEqual(calls, 3)
 
 
 if __name__ == "__main__":