From 8dc7653cb29d1c8db0b1b626d83663a7137b64a4 Mon Sep 17 00:00:00 2001
From: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
Date: Sun, 5 Jul 2026 21:08:46 -0400
Subject: [PATCH] Pass float session timeout to sse_client; update
 timeout-message assertions (SDK v2)

---
 fastmcp_slim/fastmcp/client/transports/sse.py | 10 +++++-----
 tests/client/test_sse.py                      |  6 +++---
 tests/client/test_streamable_http.py          |  2 +-
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/fastmcp_slim/fastmcp/client/transports/sse.py b/fastmcp_slim/fastmcp/client/transports/sse.py
index 8c2d7c167..09e7fff5c 100644
--- a/fastmcp_slim/fastmcp/client/transports/sse.py
+++ b/fastmcp_slim/fastmcp/client/transports/sse.py
@@ -134,11 +134,11 @@ class SSETransport(ClientTransport):
         # instead we simply leave the kwarg out if it's not provided
         if self.sse_read_timeout is not None:
             client_kwargs["sse_read_timeout"] = self.sse_read_timeout.total_seconds()
-        if session_kwargs.get("read_timeout_seconds") is not None:
-            read_timeout_seconds = cast(
-                datetime.timedelta, session_kwargs.get("read_timeout_seconds")
-            )
-            client_kwargs["timeout"] = read_timeout_seconds.total_seconds()
+        # SDK v2 session read timeouts are float seconds (see SessionKwargs);
+        # sse_client's `timeout` param is likewise float seconds.
+        read_timeout_seconds = session_kwargs.get("read_timeout_seconds")
+        if read_timeout_seconds is not None:
+            client_kwargs["timeout"] = read_timeout_seconds
 
         if self.httpx_client_factory is not None:
             client_kwargs["httpx_client_factory"] = self.httpx_client_factory
diff --git a/tests/client/test_sse.py b/tests/client/test_sse.py
index beb5b857e..eb94faa75 100644
--- a/tests/client/test_sse.py
+++ b/tests/client/test_sse.py
@@ -162,7 +162,7 @@ class TestTimeout:
     async def test_timeout(self, sse_server: str):
         with pytest.raises(
             MCPError,
-            match="Timed out while waiting for response to ClientRequest. Waited 0.03 seconds",
+            match="timed out",
         ):
             async with Client(
                 transport=SSETransport(sse_server),
@@ -172,7 +172,7 @@ class TestTimeout:
 
     async def test_timeout_tool_call(self, sse_server: str):
         async with Client(transport=SSETransport(sse_server)) as client:
-            with pytest.raises(MCPError, match="Timed out"):
+            with pytest.raises(MCPError, match="timed out"):
                 await client.call_tool("sleep", {"seconds": 0.1}, timeout=0.03)
 
     async def test_timeout_tool_call_overrides_client_timeout_if_lower(
@@ -182,7 +182,7 @@ class TestTimeout:
             transport=SSETransport(sse_server),
             timeout=2,
         ) as client:
-            with pytest.raises(MCPError, match="Timed out"):
+            with pytest.raises(MCPError, match="timed out"):
                 await client.call_tool("sleep", {"seconds": 0.1}, timeout=0.03)
 
     async def test_timeout_client_timeout_does_not_override_tool_call_timeout_if_lower(
diff --git a/tests/client/test_streamable_http.py b/tests/client/test_streamable_http.py
index 85594ade9..c802d7929 100644
--- a/tests/client/test_streamable_http.py
+++ b/tests/client/test_streamable_http.py
@@ -266,7 +266,7 @@ class TestTimeout:
     async def test_timeout(self, streamable_http_server: str):
         # note this transport behaves differently than others and raises
         # MCPError from the *client* context
-        with pytest.raises(MCPError, match="Timed out"):
+        with pytest.raises(MCPError, match="timed out"):
             async with Client(
                 transport=StreamableHttpTransport(streamable_http_server),
                 timeout=0.02,