@@ -0,0 +1,367 @@
+"""MCP unified conformance test client.
+
+This client is designed to work with the @modelcontextprotocol/conformance npm package.
+It handles all conformance test scenarios via environment variables and CLI arguments.
+
+Contract:
+    - MCP_CONFORMANCE_SCENARIO env var -> scenario name
+    - MCP_CONFORMANCE_CONTEXT env var -> optional JSON (for client-credentials scenarios)
+    - Server URL as last CLI argument (sys.argv[1])
+    - Must exit 0 within 30 seconds
+
+Scenarios:
+    initialize                              - Connect, initialize, list tools, close
+    tools_call                              - Connect, call add_numbers(a=5, b=3), close
+    sse-retry                               - Connect, call test_reconnection, close
+    elicitation-sep1034-client-defaults     - Elicitation with default accept callback
+    auth/client-credentials-jwt             - Client credentials with private_key_jwt
+    auth/client-credentials-basic           - Client credentials with client_secret_basic
+    auth/*                                  - Authorization code flow (default for auth scenarios)
+"""
+
+import asyncio
+import json
+import logging
+import os
+import sys
+from collections.abc import Callable, Coroutine
+from typing import Any, cast
+from urllib.parse import parse_qs, urlparse
+
+import httpx
+from pydantic import AnyUrl
+
+from mcp import ClientSession, types
+from mcp.client.auth import OAuthClientProvider, TokenStorage
+from mcp.client.auth.extensions.client_credentials import (
+    ClientCredentialsOAuthProvider,
+    PrivateKeyJWTOAuthProvider,
+    SignedJWTParameters,
+)
+from mcp.client.streamable_http import streamable_http_client
+from mcp.shared.auth import OAuthClientInformationFull, OAuthClientMetadata, OAuthToken
+from mcp.shared.context import RequestContext
+
+# Set up logging to stderr (stdout is for conformance test output)
+logging.basicConfig(
+    level=logging.DEBUG,
+    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+    stream=sys.stderr,
+)
+logger = logging.getLogger(__name__)
+
+# Type for async scenario handler functions
+ScenarioHandler = Callable[[str], Coroutine[Any, None, None]]
+
+# Registry of scenario handlers
+HANDLERS: dict[str, ScenarioHandler] = {}
+
+
+def register(name: str) -> Callable[[ScenarioHandler], ScenarioHandler]:
+    """Register a scenario handler."""
+
+    def decorator(fn: ScenarioHandler) -> ScenarioHandler:
+        HANDLERS[name] = fn
+        return fn
+
+    return decorator
+
+
+def get_conformance_context() -> dict[str, Any]:
+    """Load conformance test context from MCP_CONFORMANCE_CONTEXT environment variable."""
+    context_json = os.environ.get("MCP_CONFORMANCE_CONTEXT")
+    if not context_json:
+        raise RuntimeError(
+            "MCP_CONFORMANCE_CONTEXT environment variable not set. "
+            "Expected JSON with client_id, client_secret, and/or private_key_pem."
+        )
+    try:
+        return json.loads(context_json)
+    except json.JSONDecodeError as e:
+        raise RuntimeError(f"Failed to parse MCP_CONFORMANCE_CONTEXT as JSON: {e}") from e
+
+
+class InMemoryTokenStorage(TokenStorage):
+    """Simple in-memory token storage for conformance testing."""
+
+    def __init__(self) -> None:
+        self._tokens: OAuthToken | None = None
+        self._client_info: OAuthClientInformationFull | None = None
+
+    async def get_tokens(self) -> OAuthToken | None:
+        return self._tokens
+
+    async def set_tokens(self, tokens: OAuthToken) -> None:
+        self._tokens = tokens
+
+    async def get_client_info(self) -> OAuthClientInformationFull | None:
+        return self._client_info
+
+    async def set_client_info(self, client_info: OAuthClientInformationFull) -> None:
+        self._client_info = client_info
+
+
+class ConformanceOAuthCallbackHandler:
+    """OAuth callback handler that automatically fetches the authorization URL
+    and extracts the auth code, without requiring user interaction.
+    """
+
+    def __init__(self) -> None:
+        self._auth_code: str | None = None
+        self._state: str | None = None
+
+    async def handle_redirect(self, authorization_url: str) -> None:
+        """Fetch the authorization URL and extract the auth code from the redirect."""
+        logger.debug(f"Fetching authorization URL: {authorization_url}")
+
+        async with httpx.AsyncClient() as client:
+            response = await client.get(
+                authorization_url,
+                follow_redirects=False,
+            )
+
+            if response.status_code in (301, 302, 303, 307, 308):
+                location = cast(str, response.headers.get("location"))
+                if location:
+                    redirect_url = urlparse(location)
+                    query_params: dict[str, list[str]] = parse_qs(redirect_url.query)
+
+                    if "code" in query_params:
+                        self._auth_code = query_params["code"][0]
+                        state_values = query_params.get("state")
+                        self._state = state_values[0] if state_values else None
+                        logger.debug(f"Got auth code from redirect: {self._auth_code[:10]}...")
+                        return
+                    else:
+                        raise RuntimeError(f"No auth code in redirect URL: {location}")
+                else:
+                    raise RuntimeError(f"No redirect location received from {authorization_url}")
+            else:
+                raise RuntimeError(f"Expected redirect response, got {response.status_code} from {authorization_url}")
+
+    async def handle_callback(self) -> tuple[str, str | None]:
+        """Return the captured auth code and state."""
+        if self._auth_code is None:
+            raise RuntimeError("No authorization code available - was handle_redirect called?")
+        auth_code = self._auth_code
+        state = self._state
+        self._auth_code = None
+        self._state = None
+        return auth_code, state
+
+
+# --- Scenario Handlers ---
+
+
+@register("initialize")
+async def run_initialize(server_url: str) -> None:
+    """Connect, initialize, list tools, close."""
+    async with streamable_http_client(url=server_url) as (read_stream, write_stream, _):
+        async with ClientSession(read_stream, write_stream) as session:
+            await session.initialize()
+            logger.debug("Initialized successfully")
+            await session.list_tools()
+            logger.debug("Listed tools successfully")
+
+
+@register("tools_call")
+async def run_tools_call(server_url: str) -> None:
+    """Connect, initialize, list tools, call add_numbers(a=5, b=3), close."""
+    async with streamable_http_client(url=server_url) as (read_stream, write_stream, _):
+        async with ClientSession(read_stream, write_stream) as session:
+            await session.initialize()
+            await session.list_tools()
+            result = await session.call_tool("add_numbers", {"a": 5, "b": 3})
+            logger.debug(f"add_numbers result: {result}")
+
+
+@register("sse-retry")
+async def run_sse_retry(server_url: str) -> None:
+    """Connect, initialize, list tools, call test_reconnection, close."""
+    async with streamable_http_client(url=server_url) as (read_stream, write_stream, _):
+        async with ClientSession(read_stream, write_stream) as session:
+            await session.initialize()
+            await session.list_tools()
+            result = await session.call_tool("test_reconnection", {})
+            logger.debug(f"test_reconnection result: {result}")
+
+
+async def default_elicitation_callback(
+    context: RequestContext["ClientSession", Any],
+    params: types.ElicitRequestParams,
+) -> types.ElicitResult | types.ErrorData:
+    """Accept elicitation and apply defaults from the schema (SEP-1034)."""
+    content: dict[str, str | int | float | bool | list[str] | None] = {}
+
+    # For form mode, extract defaults from the requested_schema
+    if isinstance(params, types.ElicitRequestFormParams):
+        schema = params.requestedSchema
+        logger.debug(f"Elicitation schema: {schema}")
+        properties = schema.get("properties", {})
+        for prop_name, prop_schema in properties.items():
+            if "default" in prop_schema:
+                content[prop_name] = prop_schema["default"]
+        logger.debug(f"Applied defaults: {content}")
+
+    return types.ElicitResult(action="accept", content=content)
+
+
+@register("elicitation-sep1034-client-defaults")
+async def run_elicitation_defaults(server_url: str) -> None:
+    """Connect with elicitation callback that applies schema defaults."""
+    async with streamable_http_client(url=server_url) as (read_stream, write_stream, _):
+        async with ClientSession(
+            read_stream, write_stream, elicitation_callback=default_elicitation_callback
+        ) as session:
+            await session.initialize()
+            await session.list_tools()
+            result = await session.call_tool("test_client_elicitation_defaults", {})
+            logger.debug(f"test_client_elicitation_defaults result: {result}")
+
+
+@register("auth/client-credentials-jwt")
+async def run_client_credentials_jwt(server_url: str) -> None:
+    """Client credentials flow with private_key_jwt authentication."""
+    context = get_conformance_context()
+    client_id = context.get("client_id")
+    private_key_pem = context.get("private_key_pem")
+    signing_algorithm = context.get("signing_algorithm", "ES256")
+
+    if not client_id:
+        raise RuntimeError("MCP_CONFORMANCE_CONTEXT missing 'client_id'")
+    if not private_key_pem:
+        raise RuntimeError("MCP_CONFORMANCE_CONTEXT missing 'private_key_pem'")
+
+    jwt_params = SignedJWTParameters(
+        issuer=client_id,
+        subject=client_id,
+        signing_algorithm=signing_algorithm,
+        signing_key=private_key_pem,
+    )
+
+    oauth_auth = PrivateKeyJWTOAuthProvider(
+        server_url=server_url,
+        storage=InMemoryTokenStorage(),
+        client_id=client_id,
+        assertion_provider=jwt_params.create_assertion_provider(),
+    )
+
+    await _run_auth_session(server_url, oauth_auth)
+
+
+@register("auth/client-credentials-basic")
+async def run_client_credentials_basic(server_url: str) -> None:
+    """Client credentials flow with client_secret_basic authentication."""
+    context = get_conformance_context()
+    client_id = context.get("client_id")
+    client_secret = context.get("client_secret")
+
+    if not client_id:
+        raise RuntimeError("MCP_CONFORMANCE_CONTEXT missing 'client_id'")
+    if not client_secret:
+        raise RuntimeError("MCP_CONFORMANCE_CONTEXT missing 'client_secret'")
+
+    oauth_auth = ClientCredentialsOAuthProvider(
+        server_url=server_url,
+        storage=InMemoryTokenStorage(),
+        client_id=client_id,
+        client_secret=client_secret,
+        token_endpoint_auth_method="client_secret_basic",
+    )
+
+    await _run_auth_session(server_url, oauth_auth)
+
+
+async def run_auth_code_client(server_url: str) -> None:
+    """Authorization code flow (default for auth/* scenarios)."""
+    callback_handler = ConformanceOAuthCallbackHandler()
+    storage = InMemoryTokenStorage()
+
+    # Check for pre-registered client credentials from context
+    context_json = os.environ.get("MCP_CONFORMANCE_CONTEXT")
+    if context_json:
+        try:
+            context = json.loads(context_json)
+            client_id = context.get("client_id")
+            client_secret = context.get("client_secret")
+            if client_id:
+                await storage.set_client_info(
+                    OAuthClientInformationFull(
+                        client_id=client_id,
+                        client_secret=client_secret,
+                        redirect_uris=[AnyUrl("http://localhost:3000/callback")],
+                        token_endpoint_auth_method="client_secret_basic" if client_secret else "none",
+                    )
+                )
+                logger.debug(f"Pre-loaded client credentials: client_id={client_id}")
+        except json.JSONDecodeError:
+            logger.exception("Failed to parse MCP_CONFORMANCE_CONTEXT")
+
+    oauth_auth = OAuthClientProvider(
+        server_url=server_url,
+        client_metadata=OAuthClientMetadata(
+            client_name="conformance-client",
+            redirect_uris=[AnyUrl("http://localhost:3000/callback")],
+            grant_types=["authorization_code", "refresh_token"],
+            response_types=["code"],
+        ),
+        storage=storage,
+        redirect_handler=callback_handler.handle_redirect,
+        callback_handler=callback_handler.handle_callback,
+        client_metadata_url="https://conformance-test.local/client-metadata.json",
+    )
+
+    await _run_auth_session(server_url, oauth_auth)
+
+
+async def _run_auth_session(server_url: str, oauth_auth: OAuthClientProvider) -> None:
+    """Common session logic for all OAuth flows."""
+    client = httpx.AsyncClient(auth=oauth_auth, timeout=30.0)
+    async with streamable_http_client(url=server_url, http_client=client) as (read_stream, write_stream, _):
+        async with ClientSession(
+            read_stream, write_stream, elicitation_callback=default_elicitation_callback
+        ) as session:
+            await session.initialize()
+            logger.debug("Initialized successfully")
+
+            tools_result = await session.list_tools()
+            logger.debug(f"Listed tools: {[t.name for t in tools_result.tools]}")
+
+            # Call the first available tool (different tests have different tools)
+            if tools_result.tools:
+                tool_name = tools_result.tools[0].name
+                try:
+                    result = await session.call_tool(tool_name, {})
+                    logger.debug(f"Called {tool_name}, result: {result}")
+                except Exception as e:
+                    logger.debug(f"Tool call result/error: {e}")
+
+    logger.debug("Connection closed successfully")
+
+
+def main() -> None:
+    """Main entry point for the conformance client."""
+    if len(sys.argv) < 2:
+        print(f"Usage: {sys.argv[0]} <server-url>", file=sys.stderr)
+        sys.exit(1)
+
+    server_url = sys.argv[1]
+    scenario = os.environ.get("MCP_CONFORMANCE_SCENARIO")
+
+    if scenario:
+        logger.debug(f"Running explicit scenario '{scenario}' against {server_url}")
+        handler = HANDLERS.get(scenario)
+        if handler:
+            asyncio.run(handler(server_url))
+        elif scenario.startswith("auth/"):
+            asyncio.run(run_auth_code_client(server_url))
+        else:
+            print(f"Unknown scenario: {scenario}", file=sys.stderr)
+            sys.exit(1)
+    else:
+        logger.debug(f"Running default auth flow against {server_url}")
+        asyncio.run(run_auth_code_client(server_url))
+
+
+if __name__ == "__main__":
+    main()
@@ -0,0 +1,9 @@
+# Known conformance test failures for v1.x
+# These are tracked and should be removed as they're fixed.
+#
+# auth/resource-mismatch: Client must validate that the Protected Resource
+# Metadata (PRM) resource field matches the server URL before proceeding
+# with authorization (RFC 8707). Implemented on main (PR #2010), needs
+# backport to v1.x.
+client:
+  - auth/resource-mismatch