fix: honor HTTP-date Retry-After in async requests

.sampo/changesets/async-retry-after-date.md

@@ -0,0 +1,5 @@
+---
+pypi/posthog: patch
+---
+
+Honor HTTP-date Retry-After headers in asynchronous requests while preserving the existing retry backoff and delay cap.

posthog/_async_request.py

@@ -11,7 +11,7 @@
 from urllib.parse import quote, urljoin, urlsplit
 
 from .capture_compression import CaptureCompression
-from .capture_v1 import _send_v1_batch
+from .capture_v1 import _parse_retry_after, _send_v1_batch
 from .request import (
     APIError,
     DatetimeSerializer,
@@ -100,21 +100,11 @@ def _serialize_flags_body(
     }
 
 
-def _parse_retry_after(response: Any) -> Optional[float]:
-    value = response.headers.get("Retry-After")
-    if value is None:
-        return None
-    try:
-        return float(value)
-    except (TypeError, ValueError):
-        return None
-
-
 def _process_response(response: Any) -> None:
     if response.status_code == 200:
         return
 
-    retry_after = _parse_retry_after(response)
+    retry_after = _parse_retry_after(response.headers.get("Retry-After"))
     try:
         payload = response.json()
         detail = payload["detail"]

posthog/test/test_async_consumer.py

@@ -1,9 +1,12 @@
 from __future__ import annotations
 
 import asyncio
+import json
 from unittest import mock
 
+import httpx
 import pytest
+from freezegun import freeze_time
 
 from posthog._async_consumer import _AsyncConsumer
 from posthog.capture_compression import CaptureCompression
@@ -60,6 +63,56 @@ async def test_request_retries_transient_failures_until_success(
     assert [call.args[0] for call in sleep.await_args_list] == expected_delays
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    ("retry_after", "expected_delay"),
+    [
+        ("Tue, 08 Sep 2026 00:00:10 GMT", 10),
+        ("Tue, 08 Sep 2026 00:01:00 GMT", 30),
+        ("Mon, 07 Sep 2026 23:59:59 GMT", 1),
+        ("5", 5),
+        ("0", 1),
+        ("-1", 1),
+        ("invalid", 1),
+        (None, 1),
+    ],
+)
+async def test_request_honors_retry_after_from_http_response(
+    retry_after, expected_delay
+):
+    headers = {"Retry-After": retry_after} if retry_after is not None else {}
+    responses = [
+        httpx.Response(503, headers=headers, json={"detail": "temporary"}),
+        httpx.Response(200, json={"ok": True}),
+    ]
+    requests = []
+
+    def handle_request(request):
+        requests.append(request)
+        return responses.pop(0)
+
+    consumer = make_consumer(retries=1)
+    batch = [{"event": "test", "distinct_id": "test-user"}]
+    async with httpx.AsyncClient(
+        base_url="https://example.com", transport=httpx.MockTransport(handle_request)
+    ) as client:
+        consumer.http_client = client
+        with (
+            freeze_time("2026-09-08 00:00:00", real_asyncio=True),
+            mock.patch(
+                "posthog._async_consumer.asyncio.sleep", new=mock.AsyncMock()
+            ) as sleep,
+        ):
+            await consumer.request(batch)
+
+    sleep.assert_awaited_once_with(expected_delay)
+    assert len(requests) == 2
+    assert [json.loads(request.content)["batch"] for request in requests] == [
+        batch,
+        batch,
+    ]
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize("status", [400, 401, 413])
 async def test_request_does_not_retry_terminal_client_errors(status):