From 76bcfc9d3a41679cd38112c74bf1e4e5e5994b18 Mon Sep 17 00:00:00 2001
From: DDDonut <265319989+daleselaji-dev@users.noreply.github.com>
Date: Thu, 6 Aug 2026 10:44:05 +0800
Subject: [PATCH 1/3] fix(client): bound empty GET stream retries

---
 src/mcp/client/streamable_http.py    |  7 +++++--
 tests/client/test_streamable_http.py | 25 +++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/mcp/client/streamable_http.py b/src/mcp/client/streamable_http.py
index 226b0fecf9..a20416dbf3 100644
--- a/src/mcp/client/streamable_http.py
+++ b/src/mcp/client/streamable_http.py
@@ -214,7 +214,9 @@ async def handle_get_stream(self, client: httpx2.AsyncClient, read_stream_writer
                     event_source.response.raise_for_status()
                     logger.debug("GET SSE connection established")
 
+                    saw_event = False
                     async for sse in event_source:
+                        saw_event = True
                         # Track last event ID for reconnection
                         if sse.id:
                             last_event_id = sse.id
@@ -224,8 +226,9 @@ async def handle_get_stream(self, client: httpx2.AsyncClient, read_stream_writer
 
                         await self._handle_sse_event(sse, read_stream_writer)
 
-                    # Stream ended normally (server closed) - reset attempt counter
-                    attempt = 0
+                    # A clean stream close is retryable only when the server sent an event.
+                    # An empty stream is a terminated endpoint, so count it against the retry budget.
+                    attempt = 0 if saw_event else attempt + 1
 
             except Exception:
                 logger.debug("GET stream error", exc_info=True)
diff --git a/tests/client/test_streamable_http.py b/tests/client/test_streamable_http.py
index d21f520daf..5afe9aa721 100644
--- a/tests/client/test_streamable_http.py
+++ b/tests/client/test_streamable_http.py
@@ -736,6 +736,31 @@ async def test_exhausted_reconnection_attempts_resolve_the_request_with_an_error
     receive.close()
 
 
+@pytest.mark.anyio
+async def test_empty_get_stream_exhausts_reconnection_attempts(monkeypatch: pytest.MonkeyPatch) -> None:
+    """An empty, cleanly closed GET stream must not reset the reconnection budget."""
+    requests: list[httpx2.Request] = []
+
+    def handler(request: httpx2.Request) -> httpx2.Response:
+        requests.append(request)
+        return httpx2.Response(200, headers={"content-type": "text/event-stream"}, content=b"")
+
+    async def no_sleep(_delay: float) -> None:
+        pass
+
+    monkeypatch.setattr("mcp.client.streamable_http.anyio.sleep", no_sleep)
+    transport = StreamableHTTPTransport("http://test/mcp")
+    transport.session_id = "session-1"
+    send, receive = create_context_streams[SessionMessage | Exception](0)
+
+    async with httpx2.AsyncClient(transport=httpx2.MockTransport(handler)) as http:
+        await transport.handle_get_stream(http, send)
+
+    assert len(requests) == MAX_RECONNECTION_ATTEMPTS
+    send.close()
+    receive.close()
+
+
 @pytest.mark.anyio
 async def test_resolving_an_abandoned_request_after_the_reader_closed_is_contained() -> None:
     """Teardown race: a stream dying after the reader closed resolves best-effort and must not crash."""

From e18574208c89eeee836004a60f8666d5bcaae926 Mon Sep 17 00:00:00 2001
From: DDDonut <265319989+daleselaji-dev@users.noreply.github.com>
Date: Thu, 6 Aug 2026 11:35:51 +0800
Subject: [PATCH 2/3] test: bound empty stream regression

---
 tests/client/test_streamable_http.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/client/test_streamable_http.py b/tests/client/test_streamable_http.py
index 5afe9aa721..5763975c04 100644
--- a/tests/client/test_streamable_http.py
+++ b/tests/client/test_streamable_http.py
@@ -754,7 +754,8 @@ async def no_sleep(_delay: float) -> None:
     send, receive = create_context_streams[SessionMessage | Exception](0)
 
     async with httpx2.AsyncClient(transport=httpx2.MockTransport(handler)) as http:
-        await transport.handle_get_stream(http, send)
+        with anyio.fail_after(5):
+            await transport.handle_get_stream(http, send)
 
     assert len(requests) == MAX_RECONNECTION_ATTEMPTS
     send.close()

From c068360453575602e935afbac61c52fae88720d8 Mon Sep 17 00:00:00 2001
From: DDDonut <265319989+daleselaji-dev@users.noreply.github.com>
Date: Thu, 6 Aug 2026 12:42:19 +0800
Subject: [PATCH 3/3] test: remove covered no-cover pragma

---
 src/mcp/client/streamable_http.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mcp/client/streamable_http.py b/src/mcp/client/streamable_http.py
index a20416dbf3..a2ed5b036a 100644
--- a/src/mcp/client/streamable_http.py
+++ b/src/mcp/client/streamable_http.py
@@ -234,7 +234,7 @@ async def handle_get_stream(self, client: httpx2.AsyncClient, read_stream_writer
                 logger.debug("GET stream error", exc_info=True)
                 attempt += 1
 
-            if attempt >= MAX_RECONNECTION_ATTEMPTS:  # pragma: no cover
+            if attempt >= MAX_RECONNECTION_ATTEMPTS:
                 logger.debug(f"GET stream max reconnection attempts ({MAX_RECONNECTION_ATTEMPTS}) exceeded")
                 return