diff --git a/internal/router/router.go b/internal/router/router.go
new file mode 100644
index 0000000..c0def3e
--- /dev/null
+++ b/internal/router/router.go
@@ -0,0 +1,105 @@
+package router
+
+import "net/http"
+
+type Middleware func(http.Handler) http.Handler
+
+type Group struct {
+	prefix     string
+	middleware []Middleware
+	mux        *http.ServeMux
+}
+
+func newGroup(mux *http.ServeMux, prefix string, mw []Middleware) *Group {
+	return &Group{prefix: prefix, middleware: mw, mux: mux}
+}
+
+func (g *Group) Use(mw ...Middleware) {
+	g.middleware = append(g.middleware, mw...)
+}
+
+type Method string
+
+const (
+	MethodGet    Method = "GET"
+	MethodPost   Method = "POST"
+	MethodPut    Method = "PUT"
+	MethodDelete Method = "DELETE"
+	MethodPatch  Method = "PATCH"
+)
+
+func (g *Group) Handle(method Method, path string, handler http.HandlerFunc) {
+	pattern := string(method) + " " + g.prefix + path
+	wrapped := chain(handler, g.middleware)
+	g.mux.Handle(pattern, wrapped)
+}
+func (g *Group) Get(path string, h http.HandlerFunc)    { g.Handle(MethodGet, path, h) }
+func (g *Group) Post(path string, h http.HandlerFunc)   { g.Handle(MethodPost, path, h) }
+func (g *Group) Put(path string, h http.HandlerFunc)    { g.Handle(MethodPut, path, h) }
+func (g *Group) Patch(path string, h http.HandlerFunc)  { g.Handle(MethodPatch, path, h) }
+func (g *Group) Delete(path string, h http.HandlerFunc) { g.Handle(MethodDelete, path, h) }
+
+// SubGroup creates a nested group with accumulated prefix and middleware.
+// Middleware added inside fn does not affect the parent group.
+func (g *Group) SubGroup(prefix string, fn func(*Group)) {
+	mw := make([]Middleware, len(g.middleware))
+	copy(mw, g.middleware)
+	sub := newGroup(g.mux, g.prefix+prefix, mw)
+	fn(sub)
+}
+
+// RouteGroup is implemented by feature modules to register their routes.
+type RouteGroup interface {
+	Prefix() string
+	Register(g *Group)
+}
+
+// MiddlewareProvider is optionally implemented by RouteGroups that need
+// group-level middleware.
+type MiddlewareProvider interface {
+	Middlewares() []Middleware
+}
+
+type Router struct {
+	mux        *http.ServeMux
+	middleware []Middleware
+}
+
+func New() *Router {
+	return &Router{mux: http.NewServeMux()}
+}
+
+func (r *Router) Mux() *http.ServeMux {
+	return r.mux
+}
+
+func (r *Router) Use(mw ...Middleware) {
+	r.middleware = append(r.middleware, mw...)
+}
+
+// Mount registers one or more RouteGroups.
+func (r *Router) Mount(groups ...RouteGroup) {
+	for _, rg := range groups {
+		var mw []Middleware
+		if mp, ok := rg.(MiddlewareProvider); ok {
+			mw = mp.Middlewares()
+		}
+		g := newGroup(r.mux, rg.Prefix(), mw)
+		rg.Register(g)
+	}
+}
+
+// Handler returns the final http.Handler with global middleware applied.
+func (r *Router) Handler() http.Handler {
+	if len(r.middleware) == 0 {
+		return r.mux
+	}
+	return chain(r.mux, r.middleware)
+}
+
+func chain(base http.Handler, mws []Middleware) http.Handler {
+	for i := len(mws) - 1; i >= 0; i-- {
+		base = mws[i](base)
+	}
+	return base
+}