Support for http request injection propagation in StreamableHttp (#833)

tests/shared/test_streamable_http.py

@@ -4,6 +4,7 @@ Tests for the StreamableHTTP server and client transport.
 Contains tests for both server and client sides of the StreamableHTTP transport.
 """
 
+import json
 import multiprocessing
 import socket
 import time
@@ -17,6 +18,7 @@ import requests
 import uvicorn
 from pydantic import AnyUrl
 from starlette.applications import Starlette
+from starlette.requests import Request
 from starlette.routing import Mount
 
 import mcp.types as types
@@ -1223,3 +1225,203 @@ async def test_streamablehttp_server_sampling(basic_server, basic_server_url):
                 captured_message_params.messages[0].content.text
                 == "Server needs client sampling"
             )
+
+
+# Context-aware server implementation for testing request context propagation
+class ContextAwareServerTest(Server):
+    def __init__(self):
+        super().__init__("ContextAwareServer")
+
+        @self.list_tools()
+        async def handle_list_tools() -> list[Tool]:
+            return [
+                Tool(
+                    name="echo_headers",
+                    description="Echo request headers from context",
+                    inputSchema={"type": "object", "properties": {}},
+                ),
+                Tool(
+                    name="echo_context",
+                    description="Echo request context with custom data",
+                    inputSchema={
+                        "type": "object",
+                        "properties": {
+                            "request_id": {"type": "string"},
+                        },
+                        "required": ["request_id"],
+                    },
+                ),
+            ]
+
+        @self.call_tool()
+        async def handle_call_tool(name: str, args: dict) -> list[TextContent]:
+            ctx = self.request_context
+
+            if name == "echo_headers":
+                # Access the request object from context
+                headers_info = {}
+                if ctx.request and isinstance(ctx.request, Request):
+                    headers_info = dict(ctx.request.headers)
+                return [
+                    TextContent(
+                        type="text",
+                        text=json.dumps(headers_info),
+                    )
+                ]
+
+            elif name == "echo_context":
+                # Return full context information
+                context_data = {
+                    "request_id": args.get("request_id"),
+                    "headers": {},
+                    "method": None,
+                    "path": None,
+                }
+                if ctx.request and isinstance(ctx.request, Request):
+                    request = ctx.request
+                    context_data["headers"] = dict(request.headers)
+                    context_data["method"] = request.method
+                    context_data["path"] = request.url.path
+                return [
+                    TextContent(
+                        type="text",
+                        text=json.dumps(context_data),
+                    )
+                ]
+
+            return [TextContent(type="text", text=f"Unknown tool: {name}")]
+
+
+# Server runner for context-aware testing
+def run_context_aware_server(port: int):
+    """Run the context-aware test server."""
+    server = ContextAwareServerTest()
+
+    session_manager = StreamableHTTPSessionManager(
+        app=server,
+        event_store=None,
+        json_response=False,
+    )
+
+    app = Starlette(
+        debug=True,
+        routes=[
+            Mount("/mcp", app=session_manager.handle_request),
+        ],
+        lifespan=lambda app: session_manager.run(),
+    )
+
+    server_instance = uvicorn.Server(
+        config=uvicorn.Config(
+            app=app,
+            host="127.0.0.1",
+            port=port,
+            log_level="error",
+        )
+    )
+    server_instance.run()
+
+
+@pytest.fixture
+def context_aware_server(basic_server_port: int) -> Generator[None, None, None]:
+    """Start the context-aware server in a separate process."""
+    proc = multiprocessing.Process(
+        target=run_context_aware_server, args=(basic_server_port,), daemon=True
+    )
+    proc.start()
+
+    # Wait for server to be running
+    max_attempts = 20
+    attempt = 0
+    while attempt < max_attempts:
+        try:
+            with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+                s.connect(("127.0.0.1", basic_server_port))
+                break
+        except ConnectionRefusedError:
+            time.sleep(0.1)
+            attempt += 1
+    else:
+        raise RuntimeError(
+            f"Context-aware server failed to start after {max_attempts} attempts"
+        )
+
+    yield
+
+    proc.kill()
+    proc.join(timeout=2)
+    if proc.is_alive():
+        print("Context-aware server process failed to terminate")
+
+
+@pytest.mark.anyio
+async def test_streamablehttp_request_context_propagation(
+    context_aware_server: None, basic_server_url: str
+) -> None:
+    """Test that request context is properly propagated through StreamableHTTP."""
+    custom_headers = {
+        "Authorization": "Bearer test-token",
+        "X-Custom-Header": "test-value",
+        "X-Trace-Id": "trace-123",
+    }
+
+    async with streamablehttp_client(
+        f"{basic_server_url}/mcp", headers=custom_headers
+    ) as (read_stream, write_stream, _):
+        async with ClientSession(read_stream, write_stream) as session:
+            result = await session.initialize()
+            assert isinstance(result, InitializeResult)
+            assert result.serverInfo.name == "ContextAwareServer"
+
+            # Call the tool that echoes headers back
+            tool_result = await session.call_tool("echo_headers", {})
+
+            # Parse the JSON response
+            assert len(tool_result.content) == 1
+            assert isinstance(tool_result.content[0], TextContent)
+            headers_data = json.loads(tool_result.content[0].text)
+
+            # Verify headers were propagated
+            assert headers_data.get("authorization") == "Bearer test-token"
+            assert headers_data.get("x-custom-header") == "test-value"
+            assert headers_data.get("x-trace-id") == "trace-123"
+
+
+@pytest.mark.anyio
+async def test_streamablehttp_request_context_isolation(
+    context_aware_server: None, basic_server_url: str
+) -> None:
+    """Test that request contexts are isolated between StreamableHTTP clients."""
+    contexts = []
+
+    # Create multiple clients with different headers
+    for i in range(3):
+        headers = {
+            "X-Request-Id": f"request-{i}",
+            "X-Custom-Value": f"value-{i}",
+            "Authorization": f"Bearer token-{i}",
+        }
+
+        async with streamablehttp_client(
+            f"{basic_server_url}/mcp", headers=headers
+        ) as (read_stream, write_stream, _):
+            async with ClientSession(read_stream, write_stream) as session:
+                await session.initialize()
+
+                # Call the tool that echoes context
+                tool_result = await session.call_tool(
+                    "echo_context", {"request_id": f"request-{i}"}
+                )
+
+                assert len(tool_result.content) == 1
+                assert isinstance(tool_result.content[0], TextContent)
+                context_data = json.loads(tool_result.content[0].text)
+                contexts.append(context_data)
+
+    # Verify each request had its own context
+    assert len(contexts) == 3
+    for i, ctx in enumerate(contexts):
+        assert ctx["request_id"] == f"request-{i}"
+        assert ctx["headers"].get("x-request-id") == f"request-{i}"
+        assert ctx["headers"].get("x-custom-value") == f"value-{i}"
+        assert ctx["headers"].get("authorization") == f"Bearer token-{i}"