Reconcile the interaction suite with main's httpx2 rename and re-drive the era-gate test through the public request seam

Port the branch-authored httpx/httpx_sse lines main's rename never saw to
httpx2, including the four aconnect_sse readers in the modern hosting
tests, and delete the dead httpx_sse import. Drive the 2026
resources/subscribe era-gate test through ClientSession.send_request
instead of the deprecated typed subscribe wrapper.

Author: maxisbey

tests/interaction/auth/test_as_handlers.py

@@ -303,7 +303,7 @@ async def test_a_non_loopback_http_redirect_uri_is_accepted_at_registration(
 
 @requirement("hosting:auth:as:register-echo-application-type")
 async def test_register_echoes_native_for_a_client_that_registered_application_type_web(
-    as_app: tuple[httpx.AsyncClient, InMemoryAuthorizationServerProvider],
+    as_app: tuple[httpx2.AsyncClient, InMemoryAuthorizationServerProvider],
 ) -> None:
     """A client registering `application_type: "web"` is told `"native"` in the registration echo.
 

tests/interaction/auth/test_flow.py

@@ -221,7 +221,7 @@ async def test_dcr_defaults_grant_types_to_authorization_code_and_refresh_token_
 
     The metadata is built directly rather than via `oauth_client_metadata()`, which sets `grant_types`.
     """
-    requests: list[httpx.Request] = []
+    requests: list[httpx2.Request] = []
     provider = InMemoryAuthorizationServerProvider()
     server = Server("guarded", on_list_tools=list_tools)
     client_metadata = OAuthClientMetadata(client_name="interaction-suite", redirect_uris=[AnyUrl(REDIRECT_URI)])
@@ -253,7 +253,7 @@ async def test_dcr_sends_consumer_set_grant_types_verbatim() -> None:
 
     The value deliberately differs from the default pair so pass-through is distinguishable from defaulting.
     """
-    requests: list[httpx.Request] = []
+    requests: list[httpx2.Request] = []
     provider = InMemoryAuthorizationServerProvider()
     server = Server("guarded", on_list_tools=list_tools)
     client_metadata = OAuthClientMetadata(
@@ -281,7 +281,7 @@ async def test_dcr_sends_a_consumer_set_application_type_verbatim() -> None:
     `"web"` against a loopback redirect URI is deliberately not what redirect-URI derivation
     would produce, so pass-through stays distinguishable from any future derivation strategy.
     """
-    requests: list[httpx.Request] = []
+    requests: list[httpx2.Request] = []
     provider = InMemoryAuthorizationServerProvider()
     server = Server("guarded", on_list_tools=list_tools)
     client_metadata = OAuthClientMetadata(

tests/interaction/lowlevel/test_mrtr.py

@@ -921,7 +921,7 @@ def _meta_envelope() -> dict[str, object]:
 async def test_retry_with_malformed_input_responses_is_rejected_with_invalid_params() -> None:
     """A retry whose inputResponses do not parse is rejected with invalid params before dispatch (spec SHOULD).
 
-    Raw httpx against the mounted modern entry: the typed API rejects garbage inputResponses at
+    Raw httpx2 against the mounted modern entry: the typed API rejects garbage inputResponses at
     construction, so the violation is unproducible above this seam.
     """
 

tests/interaction/lowlevel/test_resources.py

@@ -264,17 +264,20 @@ async def test_resources_subscribe_on_a_2026_connection_is_method_not_found_desp
     """On a 2026-07-28 connection, `resources/subscribe` is METHOD_NOT_FOUND even with a handler registered.
 
     resources/subscribe is removed from the 2026-07-28 surface; the registry rejects it before handler lookup.
+    The request is sent through the generic `send_request` seam because the typed subscribe method
+    is retired along with the 2025-era capability it drives.
     """
 
     async def subscribe_resource(ctx: ServerRequestContext, params: types.SubscribeRequestParams) -> EmptyResult:
         """Registered so the rejection provably comes from the era gate, not a missing handler."""
         raise NotImplementedError
 
     server = Server("library", on_subscribe_resource=subscribe_resource)
+    subscribe = types.SubscribeRequest(params=types.SubscribeRequestParams(uri="file:///watched.txt"))
 
     async with connect(server) as client:
         with pytest.raises(MCPError) as exc_info:
-            await client.subscribe_resource("file:///watched.txt")
+            await client.session.send_request(subscribe, EmptyResult)
 
     assert exc_info.value.error == snapshot(
         ErrorData(code=METHOD_NOT_FOUND, message="Method not found", data="resources/subscribe")

tests/interaction/transports/test_hosting_http_modern.py

@@ -14,7 +14,6 @@
 import anyio
 import httpx2
 import pytest
-from httpx_sse import aconnect_sse
 from inline_snapshot import snapshot
 from mcp_types import (
     CLIENT_CAPABILITIES_META_KEY,
@@ -684,9 +683,9 @@ async def call_tool(ctx: ServerRequestContext, params: CallToolRequestParams) ->
 
     server = Server("sentinel-name", on_list_tools=list_tools, on_call_tool=call_tool)
 
-    requests: list[httpx.Request] = []
+    requests: list[httpx2.Request] = []
 
-    async def on_request(request: httpx.Request) -> None:
+    async def on_request(request: httpx2.Request) -> None:
         requests.append(request)
 
     discover = DiscoverResult(
@@ -717,9 +716,9 @@ async def test_sentinel_lookalike_argument_value_is_base64_wrapped_in_its_param_
 
     Spec-mandated by the sentinel-collision rule, the only encoding trigger: the value is otherwise header-safe ASCII.
     """
-    requests: list[httpx.Request] = []
+    requests: list[httpx2.Request] = []
 
-    async def on_request(request: httpx.Request) -> None:
+    async def on_request(request: httpx2.Request) -> None:
         requests.append(request)
 
     discover = DiscoverResult(
@@ -757,9 +756,9 @@ async def test_null_and_absent_annotated_arguments_emit_no_param_headers_and_the
     argument against its `Mcp-Param-*` header and would reject an orphan header for the null or
     absent argument (a header matching no annotation is ignored).
     """
-    requests: list[httpx.Request] = []
+    requests: list[httpx2.Request] = []
 
-    async def on_request(request: httpx.Request) -> None:
+    async def on_request(request: httpx2.Request) -> None:
         requests.append(request)
 
     discover = DiscoverResult(
@@ -971,11 +970,11 @@ async def call_tool(ctx: ServerRequestContext, params: CallToolRequestParams) ->
     with anyio.fail_after(5):
         async with (
             mounted_app(Server("modern", on_call_tool=call_tool)) as (http, _),
-            aconnect_sse(
-                http, "POST", "/mcp", json=body, headers=_modern_headers(method="tools/call", name="noisy")
+            http.sse(
+                "/mcp", method="POST", json=body, headers=_modern_headers(method="tools/call", name="noisy")
             ) as source,
         ):
-            events = [event async for event in source.aiter_sse()]
+            events = [event async for event in source]
 
     assert source.response.status_code == 200
     assert source.response.headers["content-type"].split(";", 1)[0] == "text/event-stream"
@@ -1023,25 +1022,25 @@ async def call_tool(ctx: ServerRequestContext, params: CallToolRequestParams) ->
 
     server = Server("scoped", on_call_tool=call_tool)
 
-    emit_responses: list[httpx.Response] = []
+    emit_responses: list[httpx2.Response] = []
     emit_frames: list[JSONRPCMessage] = []
-    quiet_responses: list[httpx.Response] = []
+    quiet_responses: list[httpx2.Response] = []
 
-    async def post_emit(http: httpx.AsyncClient) -> None:
+    async def post_emit(http: httpx2.AsyncClient) -> None:
         body = {
             "jsonrpc": "2.0",
             "id": 1,
             "method": "tools/call",
             "params": {"name": "emit", "arguments": {}, "_meta": _meta_envelope()},
         }
-        async with aconnect_sse(
-            http, "POST", "/mcp", json=body, headers=_modern_headers(method="tools/call", name="emit")
+        async with http.sse(
+            "/mcp", method="POST", json=body, headers=_modern_headers(method="tools/call", name="emit")
         ) as source:
-            events = [event async for event in source.aiter_sse()]
+            events = [event async for event in source]
             emit_responses.append(source.response)
             emit_frames.extend(parse_sse_messages(events))
 
-    async def post_quiet(http: httpx.AsyncClient) -> None:
+    async def post_quiet(http: httpx2.AsyncClient) -> None:
         body = {
             "jsonrpc": "2.0",
             "id": 2,
@@ -1111,12 +1110,12 @@ async def call_tool(ctx: ServerRequestContext, params: CallToolRequestParams) ->
     with anyio.fail_after(5):
         async with (
             mounted_app(Server("modern", on_call_tool=call_tool)) as (http, _),
-            aconnect_sse(
-                http, "POST", "/mcp", json=body, headers=_modern_headers(method="tools/call", name="noisy")
+            http.sse(
+                "/mcp", method="POST", json=body, headers=_modern_headers(method="tools/call", name="noisy")
             ) as source,
         ):
             # Drained only so teardown is clean.
-            async for _ in source.aiter_sse():
+            async for _ in source:
                 pass
 
     assert source.response.headers["x-accel-buffering"] == "no"
@@ -1227,7 +1226,7 @@ async def test_modern_encoded_mcp_name_matching_the_body_after_decode_is_served(
     """A sentinel-encoded ``Mcp-Name`` whose decoded value matches the body is served, not rejected.
 
     Spec-mandated: the server decodes the header before validation -- a plain string comparison
-    would have answered 400 HeaderMismatch. The typed client sends ASCII bare, hence raw httpx.
+    would have answered 400 HeaderMismatch. The typed client sends ASCII bare, hence raw httpx2.
     """
     body = {
         "jsonrpc": "2.0",
@@ -1262,9 +1261,9 @@ async def get_prompt(ctx: ServerRequestContext, params: GetPromptRequestParams)
 
     server = Server("sentinel-prompt", on_get_prompt=get_prompt)
 
-    requests: list[httpx.Request] = []
+    requests: list[httpx2.Request] = []
 
-    async def on_request(request: httpx.Request) -> None:
+    async def on_request(request: httpx2.Request) -> None:
         requests.append(request)
 
     discover = DiscoverResult(
@@ -1324,11 +1323,11 @@ async def call_tool(ctx: ServerRequestContext, params: CallToolRequestParams) ->
     }
     with anyio.fail_after(5):
         async with mounted_app(Server("modern", on_call_tool=call_tool)) as (http, _):
-            async with aconnect_sse(
-                http, "POST", "/mcp", json=body, headers=_modern_headers(method="tools/call", name="park")
+            async with http.sse(
+                "/mcp", method="POST", json=body, headers=_modern_headers(method="tools/call", name="park")
             ) as source:
                 # Advanced once only: a full `async for` would wait for the close that is ours to perform.
-                events = source.aiter_sse()
+                events = aiter(source)
                 first = await anext(events)
             # Awaited while the app is still mounted: after mounted_app exits, the bridge's
             # teardown cancellation would make this pass vacuously.
@@ -1458,7 +1457,7 @@ async def test_modern_mcp_param_header_disagreeing_with_body_argument_is_rejecte
 
     Spec-mandated: the server resolves the ``x-mcp-header`` annotation from the tool's advertised
     ``inputSchema`` via its own tools/list handler and rejects the decoded-header/body disagreement
-    before dispatch. Raw httpx because the HTTP status is a wire-only observable and the typed
+    before dispatch. Raw httpx2 because the HTTP status is a wire-only observable and the typed
     client cannot emit a mismatching header by construction.
     """