feat: implement MCP HTTP server endpoint with authentication (#18670)

# Add MCP HTTP server with streamable transport support

- Add MCP HTTP server with streamable transport support
- Integrate with existing toolsdk for Coder workspace operations
- Add comprehensive E2E tests with OAuth2 bearer token support
- Register MCP endpoint at /api/experimental/mcp/http with authentication
- Support RFC 6750 Bearer token authentication for MCP clients

Change-Id: Ib9024569ae452729908797c42155006aa04330af
Signed-off-by: Thomas Kosiewski <tk@coder.com>

coderd/mcp/mcp.go

@@ -0,0 +1,135 @@
+package mcp
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/mark3labs/mcp-go/mcp"
+	"github.com/mark3labs/mcp-go/server"
+	"golang.org/x/xerrors"
+
+	"cdr.dev/slog"
+
+	"github.com/coder/coder/v2/buildinfo"
+	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/coder/v2/codersdk/toolsdk"
+)
+
+const (
+	// MCPServerName is the name used for the MCP server.
+	MCPServerName = "Coder"
+	// MCPServerInstructions is the instructions text for the MCP server.
+	MCPServerInstructions = "Coder MCP Server providing workspace and template management tools"
+)
+
+// Server represents an MCP HTTP server instance
+type Server struct {
+	Logger slog.Logger
+
+	// mcpServer is the underlying MCP server
+	mcpServer *server.MCPServer
+
+	// streamableServer handles HTTP transport
+	streamableServer *server.StreamableHTTPServer
+}
+
+// NewServer creates a new MCP HTTP server
+func NewServer(logger slog.Logger) (*Server, error) {
+	// Create the core MCP server
+	mcpSrv := server.NewMCPServer(
+		MCPServerName,
+		buildinfo.Version(),
+		server.WithInstructions(MCPServerInstructions),
+	)
+
+	// Create logger adapter for mcp-go
+	mcpLogger := &mcpLoggerAdapter{logger: logger}
+
+	// Create streamable HTTP server with configuration
+	streamableServer := server.NewStreamableHTTPServer(mcpSrv,
+		server.WithHeartbeatInterval(30*time.Second),
+		server.WithLogger(mcpLogger),
+	)
+
+	return &Server{
+		Logger:           logger,
+		mcpServer:        mcpSrv,
+		streamableServer: streamableServer,
+	}, nil
+}
+
+// ServeHTTP implements http.Handler interface
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	s.streamableServer.ServeHTTP(w, r)
+}
+
+// RegisterTools registers all available MCP tools with the server
+func (s *Server) RegisterTools(client *codersdk.Client) error {
+	if client == nil {
+		return xerrors.New("client cannot be nil: MCP HTTP server requires authenticated client")
+	}
+
+	// Create tool dependencies
+	toolDeps, err := toolsdk.NewDeps(client)
+	if err != nil {
+		return xerrors.Errorf("failed to initialize tool dependencies: %w", err)
+	}
+
+	// Register all available tools
+	for _, tool := range toolsdk.All {
+		s.mcpServer.AddTools(mcpFromSDK(tool, toolDeps))
+	}
+
+	return nil
+}
+
+// mcpFromSDK adapts a toolsdk.Tool to go-mcp's server.ServerTool
+func mcpFromSDK(sdkTool toolsdk.GenericTool, tb toolsdk.Deps) server.ServerTool {
+	if sdkTool.Schema.Properties == nil {
+		panic("developer error: schema properties cannot be nil")
+	}
+
+	return server.ServerTool{
+		Tool: mcp.Tool{
+			Name:        sdkTool.Name,
+			Description: sdkTool.Description,
+			InputSchema: mcp.ToolInputSchema{
+				Type:       "object",
+				Properties: sdkTool.Schema.Properties,
+				Required:   sdkTool.Schema.Required,
+			},
+		},
+		Handler: func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+			var buf bytes.Buffer
+			if err := json.NewEncoder(&buf).Encode(request.Params.Arguments); err != nil {
+				return nil, xerrors.Errorf("failed to encode request arguments: %w", err)
+			}
+			result, err := sdkTool.Handler(ctx, tb, buf.Bytes())
+			if err != nil {
+				return nil, err
+			}
+			return &mcp.CallToolResult{
+				Content: []mcp.Content{
+					mcp.NewTextContent(string(result)),
+				},
+			}, nil
+		},
+	}
+}
+
+// mcpLoggerAdapter adapts slog.Logger to the mcp-go util.Logger interface
+type mcpLoggerAdapter struct {
+	logger slog.Logger
+}
+
+func (l *mcpLoggerAdapter) Infof(format string, v ...any) {
+	l.logger.Info(context.Background(), fmt.Sprintf(format, v...))
+}
+
+func (l *mcpLoggerAdapter) Errorf(format string, v ...any) {
+	l.logger.Error(context.Background(), fmt.Sprintf(format, v...))
+}