Restore async iterator compatibility

src/httpx2/CHANGELOG.md

@@ -4,6 +4,14 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## Unreleased
+
+### Fixed
+
+* Restore `AsyncIterator[bytes]` as the return annotation of `Response.aiter_bytes()` and
+  `Response.aiter_raw()`, so that they can be overridden with any async iterator.
+  ([#1168](https://github.com/pydantic/httpx2/pull/1168))
+
 ## 2.12.0 (August 18th, 2026)
 
 ### Changed

src/httpx2/httpx2/_models.py

@@ -972,11 +972,13 @@ async def aread(self) -> bytes:
         Read and return the response content.
         """
         if not hasattr(self, "_content"):
-            async with contextlib.aclosing(self.aiter_bytes()) as parts:
+            parts = self.aiter_bytes()
+            closing = contextlib.aclosing(parts) if isinstance(parts, AsyncGenerator) else contextlib.nullcontext()
+            async with closing:
                 self._content = b"".join([part async for part in parts])
         return self._content
 
-    async def aiter_bytes(self, chunk_size: int | None = None) -> typing.AsyncGenerator[bytes, None]:
+    async def aiter_bytes(self, chunk_size: int | None = None) -> typing.AsyncIterator[bytes]:
         """
         A byte-iterator over the decoded response content.
         This allows us to handle gzip, deflate, brotli, and zstd encoded responses.
@@ -989,7 +991,13 @@ async def aiter_bytes(self, chunk_size: int | None = None) -> typing.AsyncGenera
             decoder = self._get_content_decoder()
             chunker = ByteChunker(chunk_size=chunk_size)
             with request_context(request=self._request):
-                async with contextlib.aclosing(self.aiter_raw()) as raw_stream:
+                raw_stream = self.aiter_raw()
+                closing = (
+                    contextlib.aclosing(raw_stream)
+                    if isinstance(raw_stream, AsyncGenerator)
+                    else contextlib.nullcontext()
+                )
+                async with closing:
                     async for raw_bytes in raw_stream:
                         for decoded in decoder.decode(raw_bytes):
                             for chunk in chunker.decode(decoded):
@@ -1028,7 +1036,7 @@ async def aiter_lines(self) -> typing.AsyncIterator[str]:
             for line in decoder.flush():
                 yield line
 
-    async def aiter_raw(self, chunk_size: int | None = None) -> typing.AsyncGenerator[bytes, None]:
+    async def aiter_raw(self, chunk_size: int | None = None) -> typing.AsyncIterator[bytes]:
         """
         A byte-iterator over the raw response content.
         """

tests/httpx2/models/test_responses.py

@@ -27,6 +27,20 @@ async def async_streaming_body() -> typing.AsyncIterator[bytes]:
     yield b"world!"
 
 
+class PlainAsyncIterator:
+    def __init__(self, chunks: list[bytes]) -> None:
+        self._chunks = iter(chunks)
+
+    def __aiter__(self) -> PlainAsyncIterator:
+        return self
+
+    async def __anext__(self) -> bytes:
+        try:
+            return next(self._chunks)
+        except StopIteration:
+            raise StopAsyncIteration from None
+
+
 def autodetect(content: bytes) -> str | None:
     return chardet.detect(content).get("encoding")
 
@@ -493,6 +507,26 @@ async def test_aiter_raw_with_chunksize() -> None:
     assert parts == [b"Hello, world!"]
 
 
+@pytest.mark.anyio
+async def test_aiter_bytes_override() -> None:
+    class CustomResponse(httpx2.Response):
+        def aiter_bytes(self, chunk_size: int | None = None) -> typing.AsyncIterator[bytes]:
+            return PlainAsyncIterator([b"Hello, ", b"world!"])
+
+    response = CustomResponse(200, content=async_streaming_body())
+    assert await response.aread() == b"Hello, world!"
+
+
+@pytest.mark.anyio
+async def test_aiter_raw_override() -> None:
+    class CustomResponse(httpx2.Response):
+        def aiter_raw(self, chunk_size: int | None = None) -> typing.AsyncIterator[bytes]:
+            return PlainAsyncIterator([b"Hello, ", b"world!"])
+
+    response = CustomResponse(200, content=async_streaming_body())
+    assert await response.aread() == b"Hello, world!"
+
+
 @pytest.mark.anyio
 async def test_aiter_raw_on_sync() -> None:
     response = httpx2.Response(