Integrate FastMCP

This commit integrates FastMCP, a high-level MCP server implementation originally written by Jeremiah Lowin,
into the official MCP SDK. It also updates dependencies and adds new dev dependencies.
It moves the existing SDK into a .lowlevel .

tests/server/fastmcp/servers/test_file_server.py

@@ -0,0 +1,114 @@
+import json
+from mcp.server.fastmcp import FastMCP
+import pytest
+from pathlib import Path
+
+
+@pytest.fixture()
+def test_dir(tmp_path_factory) -> Path:
+    """Create a temporary directory with test files."""
+    tmp = tmp_path_factory.mktemp("test_files")
+
+    # Create test files
+    (tmp / "example.py").write_text("print('hello world')")
+    (tmp / "readme.md").write_text("# Test Directory\nThis is a test.")
+    (tmp / "config.json").write_text('{"test": true}')
+
+    return tmp
+
+
+@pytest.fixture
+def mcp() -> FastMCP:
+    mcp = FastMCP()
+
+    return mcp
+
+
+@pytest.fixture(autouse=True)
+def resources(mcp: FastMCP, test_dir: Path) -> FastMCP:
+    @mcp.resource("dir://test_dir")
+    def list_test_dir() -> list[str]:
+        """List the files in the test directory"""
+        return [str(f) for f in test_dir.iterdir()]
+
+    @mcp.resource("file://test_dir/example.py")
+    def read_example_py() -> str:
+        """Read the example.py file"""
+        try:
+            return (test_dir / "example.py").read_text()
+        except FileNotFoundError:
+            return "File not found"
+
+    @mcp.resource("file://test_dir/readme.md")
+    def read_readme_md() -> str:
+        """Read the readme.md file"""
+        try:
+            return (test_dir / "readme.md").read_text()
+        except FileNotFoundError:
+            return "File not found"
+
+    @mcp.resource("file://test_dir/config.json")
+    def read_config_json() -> str:
+        """Read the config.json file"""
+        try:
+            return (test_dir / "config.json").read_text()
+        except FileNotFoundError:
+            return "File not found"
+
+    return mcp
+
+
+@pytest.fixture(autouse=True)
+def tools(mcp: FastMCP, test_dir: Path) -> FastMCP:
+    @mcp.tool()
+    def delete_file(path: str) -> bool:
+        # ensure path is in test_dir
+        if Path(path).resolve().parent != test_dir:
+            raise ValueError(f"Path must be in test_dir: {path}")
+        Path(path).unlink()
+        return True
+
+    return mcp
+
+
+async def test_list_resources(mcp: FastMCP):
+    resources = await mcp.list_resources()
+    assert len(resources) == 4
+
+    assert [str(r.uri) for r in resources] == [
+        "dir://test_dir",
+        "file://test_dir/example.py",
+        "file://test_dir/readme.md",
+        "file://test_dir/config.json",
+    ]
+
+
+async def test_read_resource_dir(mcp: FastMCP):
+    files = await mcp.read_resource("dir://test_dir")
+    files = json.loads(files)
+
+    assert sorted([Path(f).name for f in files]) == [
+        "config.json",
+        "example.py",
+        "readme.md",
+    ]
+
+
+async def test_read_resource_file(mcp: FastMCP):
+    result = await mcp.read_resource("file://test_dir/example.py")
+    assert result == "print('hello world')"
+
+
+async def test_delete_file(mcp: FastMCP, test_dir: Path):
+    await mcp.call_tool(
+        "delete_file", arguments=dict(path=str(test_dir / "example.py"))
+    )
+    assert not (test_dir / "example.py").exists()
+
+
+async def test_delete_file_and_check_resources(mcp: FastMCP, test_dir: Path):
+    await mcp.call_tool(
+        "delete_file", arguments=dict(path=str(test_dir / "example.py"))
+    )
+    result = await mcp.read_resource("file://test_dir/example.py")
+    assert result == "File not found"