_stream_rejection discards bytes already read, so it works only by luck of buffer sizes

changelog.d/tsk-ocjut3-stream-rejection-buffer.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- `_stream_rejection` in `tests/test_a2a.py` now accumulates all received data into a single buffer until the `\r\n\r\n` separator is found, instead of discarding already-read bytes across separate 128-byte chunk reads. This eliminates the latent fragility where the function worked only by luck of buffer sizes.

tests/test_a2a.py

@@ -368,41 +368,31 @@ def _stream_rejection(live_server: str, path: str, timeout: float = 3.0) -> tupl
             f"GET {path} HTTP/1.1\r\nHost: {host}:{port}\r\nConnection: close\r\n\r\n".encode()
         )
         sock.settimeout(timeout)
-        line = b""
-        while b"\r\n" not in line:
+        data = b""
+        while b"\r\n\r\n" not in data:
             try:
-                chunk = sock.recv(128)
+                chunk = sock.recv(4096)
             except (socket.timeout, TimeoutError) as exc:
-                raise AssertionError(f"timed out reading stream status line: {exc}") from exc
+                raise AssertionError(f"timed out reading stream response: {exc}") from exc
             if not chunk:
                 break
-            line += chunk
-        status_line = line.decode("utf-8", "replace").splitlines()[0]
+            data += chunk
+
+        header_text, _, body_text = data.partition(b"\r\n\r\n")
+
+        status_line = header_text.decode("utf-8", "replace").splitlines()[0]
         status = int(status_line.split()[1])
 
         if status == 200:
             return status, None
 
-        headers_raw = b""
-        while b"\r\n\r\n" not in headers_raw:
-            try:
-                chunk = sock.recv(128)
-            except (socket.timeout, TimeoutError) as exc:
-                raise AssertionError(f"timed out reading response headers: {exc}") from exc
-            if not chunk:
-                break
-            headers_raw += chunk
-
-        header_text = headers_raw.decode("utf-8", "replace")
-        body_start = header_text.find("\r\n\r\n") + 4
-        body_bytes = header_text[body_start:].encode("utf-8")
-
         content_length = None
-        for h in header_text.splitlines()[1:]:
+        for h in header_text.decode("utf-8", "replace").splitlines()[1:]:
             if h.lower().startswith("content-length:"):
                 content_length = int(h.split(":", 1)[1].strip())
                 break
 
+        body_bytes = body_text
         if content_length is not None:
             remaining = content_length - len(body_bytes)
             while remaining > 0: