Upgrade to FastMCP 4 for MCP discovery support

conduit/tests/test_protocol_compatibility.py

@@ -0,0 +1,88 @@
+"""Wire-level checks for the MCP protocol versions used by clients."""
+
+import json
+from unittest import IsolatedAsyncioTestCase
+
+import httpx
+
+from conduit.conduit import ConduitApp, PhabricatorConfig
+
+
+class TestProtocolCompatibility(IsolatedAsyncioTestCase):
+    def setUp(self):
+        config = PhabricatorConfig(token="x" * 32, url="https://example.invalid/api/")
+        conduit = ConduitApp(config, transport="http")
+        conduit.register_tools()
+        self.asgi_app = conduit.mcp.http_app(path="/mcp", stateless_http=True)
+
+    async def _post(self, client, method, params, version):
+        headers = {
+            "Accept": "application/json, text/event-stream",
+            "MCP-Protocol-Version": version,
+        }
+        if version == "2026-07-28":
+            headers["Mcp-Method"] = method
+
+        response = await client.post(
+            "/mcp",
+            json={"jsonrpc": "2.0", "id": 1, "method": method, "params": params},
+            headers=headers,
+        )
+        self.assertEqual(response.status_code, 200)
+        if response.headers["content-type"].startswith("text/event-stream"):
+            data = next(
+                line.removeprefix("data: ")
+                for line in response.text.splitlines()
+                if line.startswith("data: ")
+            )
+            return json.loads(data)
+        return response.json()
+
+    async def test_modern_discovery_and_tool_listing(self):
+        meta = {
+            "io.modelcontextprotocol/protocolVersion": "2026-07-28",
+            "io.modelcontextprotocol/clientInfo": {"name": "test", "version": "1"},
+            "io.modelcontextprotocol/clientCapabilities": {},
+        }
+        async with self.asgi_app.lifespan(self.asgi_app):
+            async with httpx.AsyncClient(
+                transport=httpx.ASGITransport(app=self.asgi_app),
+                base_url="http://localhost",
+            ) as client:
+                discovery = await self._post(
+                    client, "server/discover", {"_meta": meta}, "2026-07-28"
+                )
+                tools = await self._post(
+                    client, "tools/list", {"_meta": meta}, "2026-07-28"
+                )
+
+        self.assertIn("2026-07-28", discovery["result"]["supportedVersions"])
+        self.assertIn("tools", discovery["result"]["capabilities"])
+        self.assertIn(
+            "pha_user_whoami",
+            {tool["name"] for tool in tools["result"]["tools"]},
+        )
+
+    async def test_legacy_initialize_and_tool_listing(self):
+        async with self.asgi_app.lifespan(self.asgi_app):
+            async with httpx.AsyncClient(
+                transport=httpx.ASGITransport(app=self.asgi_app),
+                base_url="http://localhost",
+            ) as client:
+                initialization = await self._post(
+                    client,
+                    "initialize",
+                    {
+                        "protocolVersion": "2025-11-25",
+                        "capabilities": {},
+                        "clientInfo": {"name": "test", "version": "1"},
+                    },
+                    "2025-11-25",
+                )
+                tools = await self._post(client, "tools/list", {}, "2025-11-25")
+
+        self.assertEqual(initialization["result"]["protocolVersion"], "2025-11-25")
+        self.assertIn(
+            "pha_user_whoami",
+            {tool["name"] for tool in tools["result"]["tools"]},
+        )

pyproject.toml

@@ -27,7 +27,8 @@ classifiers = [
     "Topic :: Software Development :: Bug Tracking",
 ]
 dependencies = [
-    "fastmcp>=3,<4",
+    "fastmcp==4.0.10",
+    "mcp==2.2.0",
     "httpx[socks]",
     "python-dotenv",
 ]
@@ -65,4 +66,4 @@ exclude = ["tests*"]
 [tool.pytest.ini_options]
 markers = [
     "integration: requires a live Phabricator/Phorge instance (deselect with '-m \"not integration\"')",
-]
+]