Ensure headers get set when rest clients receive an aiohttp.ClientSession instance

changelog.md

@@ -1,3 +1,14 @@
+# Microsoft 365 Agents SDK for Python - Release Notes v1.9.0 (Unreleased)
+
+**Release Date:** Unreleased
+**Previous Version:** 1.8.0 (Released 2026-10-01)
+
+## Bug Fixes
+
+- **Connector User-Agent Headers**: Added the SDK `User-Agent` header to `MCSConnectorClient` and ensured `ConnectorClient`, `TeamsConnectorClient`, and `UserTokenClient` apply it to caller-provided `ClientSession` instances.
+
+---
+
 # Microsoft 365 Agents SDK for Python - Release Notes v1.8.0
 
 **Release Date:** 2026-10-01

libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/connector/client/connector_client.py

@@ -781,18 +781,17 @@ def __init__(
         if not endpoint.endswith("/"):
             endpoint += "/"
 
+        # Create session with the base URL
+        session = session or ClientSession(base_url=endpoint)
+
         # Configure headers with JSON acceptance
         headers = {
             "Accept": "application/json",
             "Content-Type": "application/json",
-            "User-Agent": get_product_info(),
+            "User-Agent": session.headers.get("User-Agent", get_product_info()),
         }
+        session.headers.update(headers)
 
-        # Create session with the base URL
-        session = session or ClientSession(
-            base_url=endpoint,
-            headers=headers,
-        )
         logger.debug(
             "ConnectorClient initialized with endpoint: %s and headers: %s",
             endpoint,

libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/connector/client/user_token_client.py

@@ -57,18 +57,16 @@ def __init__(
         if not endpoint.endswith("/"):
             endpoint += "/"
 
+        # Create session with the base URL
+        session = session or ClientSession(base_url=endpoint)
+
         # Configure headers with JSON acceptance
         headers = {
             "Accept": "application/json",
             "Content-Type": "application/json",
-            "User-Agent": get_product_info(),
+            "User-Agent": session.headers.get("User-Agent", get_product_info()),
         }
-
-        # Create session with the base URL
-        session = session or ClientSession(
-            base_url=endpoint,
-            headers=headers,
-        )
+        session.headers.update(headers)
         logger.debug(
             "Creating UserTokenClient with endpoint: %s and headers: %s",
             endpoint,

libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/connector/mcs/mcs_connector_client.py

@@ -14,6 +14,7 @@
 from ..conversations_base import ConversationsBase
 from ..client._base_client import _BaseClient
 from .._utils import _handle_request_error
+from ..get_product_info import get_product_info
 
 logger = logging.getLogger(__name__)
 
@@ -224,6 +225,13 @@ def __init__(self, endpoint: str, client: Optional[ClientSession] = None):
 
         self._endpoint = endpoint
         self._client = client or ClientSession()
+        headers = {
+            "Accept": "application/json",
+            "Content-Type": "application/json",
+            "User-Agent": self._client.headers.get("User-Agent", get_product_info()),
+        }
+        self._client.headers.update(headers)
+
         self._conversations = MCSConversations(self._client, self._endpoint)
         self._attachments = MCSAttachments()
 

tests/hosting_core/connector/test_connector_client.py

@@ -21,6 +21,8 @@
     ConnectorClient,
     ConversationsOperations,
 )
+from microsoft_agents.hosting.core.connector.get_product_info import get_product_info
+from microsoft_agents.hosting.core.connector.teams import TeamsConnectorClient
 from microsoft_agents.hosting.core.header_propagation import HeaderPropagationContext
 
 
@@ -945,3 +947,77 @@ async def handler(request):
             assert "conv_sub_id" in captured["raw_path"]
         finally:
             await server.close()
+
+
+class TestUserAgentHeader:
+    """Ensures ConnectorClient and TeamsConnectorClient send a User-Agent header."""
+
+    @pytest.mark.asyncio
+    async def test_connector_client_sets_user_agent_header(self):
+        client = ConnectorClient(endpoint="https://example.org/", token="token")
+        try:
+            assert client.client.headers["User-Agent"] == get_product_info()
+        finally:
+            await client.client.close()
+
+    @pytest.mark.asyncio
+    async def test_connector_client_sends_user_agent_header_on_request(self):
+        captured = {}
+
+        async def handler(request):
+            captured["user_agent"] = request.headers.get("User-Agent")
+            return web.json_response({"id": "activity-id-123"})
+
+        routes = [web.post("/v3/conversations/{conversation_id}/activities", handler)]
+        app = _create_app(routes)
+
+        server = TestServer(app)
+        await server.start_server()
+        session = ClientSession(base_url=str(server.make_url("/")))
+        try:
+            client = ConnectorClient(
+                endpoint=str(server.make_url("/")), token="token", session=session
+            )
+            assert client.client is session
+            await client.conversations.send_to_conversation(
+                "conv-1", Activity(type="message", text="hi")
+            )
+        finally:
+            await server.close()
+            await session.close()
+
+        assert captured["user_agent"] == get_product_info()
+
+    @pytest.mark.asyncio
+    async def test_teams_connector_client_sets_user_agent_header(self):
+        client = TeamsConnectorClient(endpoint="https://example.org/", token="token")
+        try:
+            assert client.client.headers["User-Agent"] == get_product_info()
+        finally:
+            await client.client.close()
+
+    @pytest.mark.asyncio
+    async def test_teams_connector_client_sends_user_agent_header_on_request(self):
+        captured = {}
+
+        async def handler(request):
+            captured["user_agent"] = request.headers.get("User-Agent")
+            return web.json_response({"id": "team-1"})
+
+        routes = [web.get("/v3/teams/{team_id}", handler)]
+        app = _create_app(routes)
+
+        server = TestServer(app)
+        await server.start_server()
+        session = ClientSession(base_url=str(server.make_url("/")))
+        try:
+            client = TeamsConnectorClient(
+                endpoint=str(server.make_url("/")), token="token", session=session
+            )
+            assert client.client is session
+            await client.fetch_team_details("team-1")
+        finally:
+            await server.close()
+            await session.close()
+
+        assert captured["user_agent"] == get_product_info()

tests/hosting_core/connector/test_mcs_connector_client.py

@@ -0,0 +1,50 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+"""Tests for MCSConnectorClient User-Agent header behavior."""
+
+import pytest
+from aiohttp import web
+from aiohttp.test_utils import TestServer
+
+from microsoft_agents.activity import Activity
+from microsoft_agents.hosting.core.connector.get_product_info import get_product_info
+from microsoft_agents.hosting.core.connector.mcs import MCSConnectorClient
+
+
+class TestMCSConnectorClientUserAgentHeader:
+    """Ensures MCSConnectorClient sends a User-Agent header."""
+
+    @pytest.mark.asyncio
+    async def test_sets_user_agent_header(self):
+        client = MCSConnectorClient(endpoint="https://example.org/endpoint")
+        try:
+            assert client._client.headers.get("User-Agent") == get_product_info()
+        finally:
+            await client.close()
+
+    @pytest.mark.asyncio
+    async def test_sends_user_agent_header_on_request(self):
+        captured = {}
+
+        async def handler(request):
+            captured["user_agent"] = request.headers.get("User-Agent")
+            return web.json_response({"id": "activity-id-123"})
+
+        app = web.Application()
+        app.router.add_post("/endpoint", handler)
+        server = TestServer(app)
+        await server.start_server()
+        try:
+            endpoint = str(server.make_url("/endpoint"))
+            client = MCSConnectorClient(endpoint=endpoint)
+            try:
+                await client.conversations.send_to_conversation(
+                    "conv-1", Activity(type="message", text="hi")
+                )
+            finally:
+                await client.close()
+        finally:
+            await server.close()
+
+        assert captured["user_agent"] == get_product_info()

tests/hosting_core/connector/test_user_token_client.py

@@ -21,6 +21,7 @@
     UserToken,
     UserTokenClient,
 )
+from microsoft_agents.hosting.core.connector.get_product_info import get_product_info
 from microsoft_agents.hosting.core.header_propagation import HeaderPropagationContext
 
 
@@ -407,3 +408,44 @@ async def handler(request):
             await server.close()
 
         assert exc_info.value.status == 500
+
+
+class TestUserTokenClientUserAgentHeader:
+    """Ensures UserTokenClient sends a User-Agent header."""
+
+    @pytest.mark.asyncio
+    async def test_sets_user_agent_header(self):
+        client = UserTokenClient("https://example.org/", token="", app_id="app-id")
+        try:
+            assert client.client.headers["User-Agent"] == get_product_info()
+        finally:
+            await client.close()
+
+    @pytest.mark.asyncio
+    async def test_sends_user_agent_header_on_request(self):
+        captured = {}
+
+        async def handler(request):
+            captured["user_agent"] = request.headers.get("User-Agent")
+            return web.json_response({"token": "token"})
+
+        app = web.Application()
+        app.router.add_get("/api/usertoken/GetToken", handler)
+        server = TestServer(app)
+        await server.start_server()
+
+        session = ClientSession(base_url=str(server.make_url("/")))
+        try:
+            client = UserTokenClient(
+                str(server.make_url("/")),
+                token="",
+                app_id="app-id",
+                session=session,
+            )
+            assert client.client is session
+            await client.get_user_token("user", "connection", "msteams")
+        finally:
+            await session.close()
+            await server.close()
+
+        assert captured["user_agent"] == get_product_info()