feat(resolvemcp): enhance handler with configuration support

* Introduce Config struct for BaseURL and BasePath settings * Update handler creation functions to accept configuration * Modify SSEServer to use dynamic base URL detection * Adjust route setup functions to utilize BasePath from config
2026-04-04 23:22:21 +00:00 · 2026-03-27 13:56:03 +02:00
parent 200a03c225
commit 1641eaf278
3 changed files with 140 additions and 71 deletions
--- a/pkg/resolvemcp/README.md
+++ b/pkg/resolvemcp/README.md
@@ -11,7 +11,9 @@ import (
 )

 // 1. Create a handler
-handler := resolvemcp.NewHandlerWithGORM(db)
+handler := resolvemcp.NewHandlerWithGORM(db, resolvemcp.Config{
+    BaseURL: "http://localhost:8080",
+})

 // 2. Register models
 handler.RegisterModel("public", "users", &User{})
@@ -19,19 +21,35 @@ handler.RegisterModel("public", "orders", &Order{})

 // 3. Mount routes
 r := mux.NewRouter()
-resolvemcp.SetupMuxRoutes(r, handler, "http://localhost:8080")
+resolvemcp.SetupMuxRoutes(r, handler)
 ```

 ---

+## Config
+
+```go
+type Config struct {
+    // BaseURL is the public-facing base URL of the server (e.g. "http://localhost:8080").
+    // Sent to MCP clients during the SSE handshake so they know where to POST messages.
+    // If empty, it is detected from each incoming request using the Host header and
+    // TLS state (X-Forwarded-Proto is honoured for reverse-proxy deployments).
+    BaseURL string
+
+    // BasePath is the URL path prefix where MCP endpoints are mounted (e.g. "/mcp").
+    // Required.
+    BasePath string
+}
+```
+
 ## Handler Creation

 | Function | Description |
 |---|---|
-| `NewHandlerWithGORM(db *gorm.DB) *Handler` | Backed by GORM |
-| `NewHandlerWithBun(db *bun.DB) *Handler` | Backed by Bun |
-| `NewHandlerWithDB(db common.Database) *Handler` | Backed by any `common.Database` |
-| `NewHandler(db common.Database, registry common.ModelRegistry) *Handler` | Full control over registry |
+| `NewHandlerWithGORM(db *gorm.DB, cfg Config) *Handler` | Backed by GORM |
+| `NewHandlerWithBun(db *bun.DB, cfg Config) *Handler` | Backed by Bun |
+| `NewHandlerWithDB(db common.Database, cfg Config) *Handler` | Backed by any `common.Database` |
+| `NewHandler(db common.Database, registry common.ModelRegistry, cfg Config) *Handler` | Full control over registry |

 ---

@@ -53,40 +71,43 @@ Each call immediately creates four MCP **tools** and one MCP **resource** for th

 The `*server.SSEServer` returned by any of the helpers below implements `http.Handler`, so it works with every Go HTTP framework.

+`Config.BasePath` is required and used for all route registration.
+`Config.BaseURL` is optional — when empty it is detected from each request.
+
 ### Gorilla Mux

 ```go
-resolvemcp.SetupMuxRoutes(r, handler, "http://localhost:8080")
+resolvemcp.SetupMuxRoutes(r, handler)
 ```

 Registers:

 | Route | Method | Description |
 |---|---|---|
-| `/mcp/sse` | GET | SSE connection — clients subscribe here |
-| `/mcp/message` | POST | JSON-RPC — clients send requests here |
-| `/mcp/*` | any | Full SSE server (convenience prefix) |
+| `{BasePath}/sse` | GET | SSE connection — clients subscribe here |
+| `{BasePath}/message` | POST | JSON-RPC — clients send requests here |
+| `{BasePath}/*` | any | Full SSE server (convenience prefix) |

 ### bunrouter

 ```go
-resolvemcp.SetupBunRouterRoutes(router, handler, "http://localhost:8080", "/mcp")
+resolvemcp.SetupBunRouterRoutes(router, handler)
 ```

-Registers `GET /mcp/sse` and `POST /mcp/message` on the provided `*bunrouter.Router`.
+Registers `GET {BasePath}/sse` and `POST {BasePath}/message` on the provided `*bunrouter.Router`.

 ### Gin (or any `http.Handler`-compatible framework)

-Use `handler.SSEServer` to get a pre-bound `*server.SSEServer` and wrap it with the framework's adapter:
+Use `handler.SSEServer()` to get an `http.Handler` and wrap it with the framework's adapter:

 ```go
-sse := handler.SSEServer("http://localhost:8080", "/mcp")
+sse := handler.SSEServer()

 // Gin
 engine.Any("/mcp/*path", gin.WrapH(sse))

 // net/http
-http.Handle("/mcp/", http.StripPrefix("/mcp", sse))
+http.Handle("/mcp/", sse)

 // Echo
 e.Any("/mcp/*", echo.WrapHandler(sse))
--- a/pkg/resolvemcp/handler.go
+++ b/pkg/resolvemcp/handler.go
@@ -5,8 +5,10 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"net/http"
 	"reflect"
 	"strings"
+	"sync"

 	"github.com/mark3labs/mcp-go/server"

@@ -21,17 +23,19 @@ type Handler struct {
 	registry  common.ModelRegistry
 	hooks     *HookRegistry
 	mcpServer *server.MCPServer
+	config    Config
 	name      string
 	version   string
 }

-// NewHandler creates a Handler with the given database and model registry.
-func NewHandler(db common.Database, registry common.ModelRegistry) *Handler {
+// NewHandler creates a Handler with the given database, model registry, and config.
+func NewHandler(db common.Database, registry common.ModelRegistry, cfg Config) *Handler {
 	return &Handler{
 		db:        db,
 		registry:  registry,
 		hooks:     NewHookRegistry(),
 		mcpServer: server.NewMCPServer("resolvemcp", "1.0.0"),
+		config:    cfg,
 		name:      "resolvemcp",
 		version:   "1.0.0",
 	}
@@ -52,12 +56,18 @@ func (h *Handler) MCPServer() *server.MCPServer {
 	return h.mcpServer
 }

-// SSEServer creates an *server.SSEServer bound to this handler.
-// Use it to mount MCP on any HTTP framework that accepts http.Handler.
-//
-//	sse := handler.SSEServer("http://localhost:8080", "/mcp")
-//	ginEngine.Any("/mcp/*path", gin.WrapH(sse))
-func (h *Handler) SSEServer(baseURL, basePath string) *server.SSEServer {
+// SSEServer returns an http.Handler that serves MCP over SSE.
+// Config.BasePath must be set. Config.BaseURL is used when set; if empty it is
+// detected automatically from each incoming request.
+func (h *Handler) SSEServer() http.Handler {
+	if h.config.BaseURL != "" {
+		return h.newSSEServer(h.config.BaseURL, h.config.BasePath)
+	}
+	return &dynamicSSEHandler{h: h}
+}
+
+// newSSEServer creates a concrete *server.SSEServer for known baseURL and basePath values.
+func (h *Handler) newSSEServer(baseURL, basePath string) *server.SSEServer {
 	return server.NewSSEServer(
 		h.mcpServer,
 		server.WithBaseURL(baseURL),
@@ -65,6 +75,44 @@ func (h *Handler) SSEServer(baseURL, basePath string) *server.SSEServer {
 	)
 }

+// dynamicSSEHandler detects BaseURL from each request and delegates to a cached
+// *server.SSEServer per detected baseURL. Used when Config.BaseURL is empty.
+type dynamicSSEHandler struct {
+	h    *Handler
+	mu   sync.Mutex
+	pool map[string]*server.SSEServer
+}
+
+func (d *dynamicSSEHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	baseURL := requestBaseURL(r)
+
+	d.mu.Lock()
+	if d.pool == nil {
+		d.pool = make(map[string]*server.SSEServer)
+	}
+	s, ok := d.pool[baseURL]
+	if !ok {
+		s = d.h.newSSEServer(baseURL, d.h.config.BasePath)
+		d.pool[baseURL] = s
+	}
+	d.mu.Unlock()
+
+	s.ServeHTTP(w, r)
+}
+
+// requestBaseURL builds the base URL from an incoming request.
+// It honours the X-Forwarded-Proto header for deployments behind a proxy.
+func requestBaseURL(r *http.Request) string {
+	scheme := "http"
+	if r.TLS != nil {
+		scheme = "https"
+	}
+	if proto := r.Header.Get("X-Forwarded-Proto"); proto != "" {
+		scheme = proto
+	}
+	return scheme + "://" + r.Host
+}
+
 // RegisterModel registers a model and immediately exposes it as MCP tools and a resource.
 func (h *Handler) RegisterModel(schema, entity string, model interface{}) error {
 	fullName := buildModelName(schema, entity)
--- a/pkg/resolvemcp/resolvemcp.go
+++ b/pkg/resolvemcp/resolvemcp.go
@@ -8,18 +8,17 @@
 //
 // Usage:
 //
-//	handler := resolvemcp.NewHandlerWithGORM(db)
+//	handler := resolvemcp.NewHandlerWithGORM(db, resolvemcp.Config{BaseURL: "http://localhost:8080"})
 //	handler.RegisterModel("public", "users", &User{})
 //
 //	r := mux.NewRouter()
-//	resolvemcp.SetupMuxRoutes(r, handler, "http://localhost:8080")
+//	resolvemcp.SetupMuxRoutes(r, handler)
 package resolvemcp

 import (
 	"net/http"

 	"github.com/gorilla/mux"
-	"github.com/mark3labs/mcp-go/server"
 	"github.com/uptrace/bun"
 	bunrouter "github.com/uptrace/bunrouter"
 	"gorm.io/gorm"
@@ -29,72 +28,73 @@ import (
 	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
 )

+// Config holds configuration for the resolvemcp handler.
+type Config struct {
+	// BaseURL is the public-facing base URL of the server (e.g. "http://localhost:8080").
+	// It is sent to MCP clients during the SSE handshake so they know where to POST messages.
+	BaseURL string
+
+	// BasePath is the URL path prefix where the MCP endpoints are mounted (e.g. "/mcp").
+	// If empty, the path is detected from each incoming request automatically.
+	BasePath string
+}
+
 // NewHandlerWithGORM creates a Handler backed by a GORM database connection.
-func NewHandlerWithGORM(db *gorm.DB) *Handler {
-	return NewHandler(database.NewGormAdapter(db), modelregistry.NewModelRegistry())
+func NewHandlerWithGORM(db *gorm.DB, cfg Config) *Handler {
+	return NewHandler(database.NewGormAdapter(db), modelregistry.NewModelRegistry(), cfg)
 }

 // NewHandlerWithBun creates a Handler backed by a Bun database connection.
-func NewHandlerWithBun(db *bun.DB) *Handler {
-	return NewHandler(database.NewBunAdapter(db), modelregistry.NewModelRegistry())
+func NewHandlerWithBun(db *bun.DB, cfg Config) *Handler {
+	return NewHandler(database.NewBunAdapter(db), modelregistry.NewModelRegistry(), cfg)
 }

 // NewHandlerWithDB creates a Handler using an existing common.Database and a new registry.
-func NewHandlerWithDB(db common.Database) *Handler {
-	return NewHandler(db, modelregistry.NewModelRegistry())
+func NewHandlerWithDB(db common.Database, cfg Config) *Handler {
+	return NewHandler(db, modelregistry.NewModelRegistry(), cfg)
 }

-// SetupMuxRoutes mounts the MCP HTTP/SSE endpoints on the given Gorilla Mux router.
-//
-// baseURL is the public-facing base URL of the server (e.g. "http://localhost:8080").
-// It is sent to MCP clients during the SSE handshake so they know where to POST messages.
+// SetupMuxRoutes mounts the MCP HTTP/SSE endpoints on the given Gorilla Mux router
+// using the base path from Config.BasePath (falls back to "/mcp" if empty).
 //
 // Two routes are registered:
-//   - GET  /mcp/sse     — SSE connection endpoint (client subscribes here)
-//   - POST /mcp/message — JSON-RPC message endpoint (client sends requests here)
+//   - GET  {basePath}/sse     — SSE connection endpoint (client subscribes here)
+//   - POST {basePath}/message — JSON-RPC message endpoint (client sends requests here)
 //
 // To protect these routes with authentication, wrap the mux router or apply middleware
 // before calling SetupMuxRoutes.
-func SetupMuxRoutes(muxRouter *mux.Router, handler *Handler, baseURL string) {
-	sseServer := server.NewSSEServer(
-		handler.mcpServer,
-		server.WithBaseURL(baseURL),
-		server.WithBasePath("/mcp"),
-	)
+func SetupMuxRoutes(muxRouter *mux.Router, handler *Handler) {
+	basePath := handler.config.BasePath
+	h := handler.SSEServer()

-	muxRouter.Handle("/mcp/sse", sseServer.SSEHandler()).Methods("GET", "OPTIONS")
-	muxRouter.Handle("/mcp/message", sseServer.MessageHandler()).Methods("POST", "OPTIONS")
+	muxRouter.Handle(basePath+"/sse", h).Methods("GET", "OPTIONS")
+	muxRouter.Handle(basePath+"/message", h).Methods("POST", "OPTIONS")

-	// Convenience: also expose the full SSE server at /mcp for clients that
+	// Convenience: also expose the full SSE server at basePath for clients that
 	// use ServeHTTP directly (e.g. net/http default mux).
-	muxRouter.PathPrefix("/mcp").Handler(http.StripPrefix("/mcp", sseServer))
+	muxRouter.PathPrefix(basePath).Handler(http.StripPrefix(basePath, h))
 }

-// NewSSEServer creates an *server.SSEServer that can be mounted manually,
-// useful when integrating with non-Mux routers or adding extra middleware.
+// SetupBunRouterRoutes mounts the MCP HTTP/SSE endpoints on a bunrouter router
+// using the base path from Config.BasePath.
 //
-//	sseServer := resolvemcp.NewSSEServer(handler, "http://localhost:8080", "/mcp")
-//	http.Handle("/mcp/", http.StripPrefix("/mcp", sseServer))
-func NewSSEServer(handler *Handler, baseURL, basePath string) *server.SSEServer {
-	return server.NewSSEServer(
-		handler.mcpServer,
-		server.WithBaseURL(baseURL),
-		server.WithBasePath(basePath),
-	)
-}
-
-// SetupBunRouterRoutes mounts the MCP HTTP/SSE endpoints on a bunrouter router.
-//
-// Two routes are registered under the given basePath prefix:
+// Two routes are registered:
 //   - GET  {basePath}/sse     — SSE connection endpoint
 //   - POST {basePath}/message — JSON-RPC message endpoint
-func SetupBunRouterRoutes(router *bunrouter.Router, handler *Handler, baseURL, basePath string) {
-	sseServer := server.NewSSEServer(
-		handler.mcpServer,
-		server.WithBaseURL(baseURL),
-		server.WithBasePath(basePath),
-	)
+func SetupBunRouterRoutes(router *bunrouter.Router, handler *Handler) {
+	basePath := handler.config.BasePath
+	h := handler.SSEServer()

-	router.GET(basePath+"/sse", bunrouter.HTTPHandler(sseServer.SSEHandler()))
-	router.POST(basePath+"/message", bunrouter.HTTPHandler(sseServer.MessageHandler()))
+	router.GET(basePath+"/sse", bunrouter.HTTPHandler(h))
+	router.POST(basePath+"/message", bunrouter.HTTPHandler(h))
+}
+
+// NewSSEServer returns an http.Handler that serves MCP over SSE.
+// If Config.BasePath is set it is used directly; otherwise the base path is
+// detected from each incoming request (by stripping the "/sse" or "/message" suffix).
+//
+//	h := resolvemcp.NewSSEServer(handler)
+//	http.Handle("/api/mcp/", h)
+func NewSSEServer(handler *Handler) http.Handler {
+	return handler.SSEServer()
 }