feat(api): add iterator-based spec group registration

Co-Authored-By: Virgil <virgil@lethean.io>

spec_registry.go

@@ -25,10 +25,27 @@ var specRegistry struct {
 //
 //	api.RegisterSpecGroups(api.NewToolBridge("/mcp"))
 func RegisterSpecGroups(groups ...RouteGroup) {
+	RegisterSpecGroupsIter(slices.Values(groups))
+}
+
+// RegisterSpecGroupsIter adds route groups from an iterator to the package-level
+// spec registry.
+//
+// Nil groups are ignored. Registered groups are returned by RegisteredSpecGroups
+// in the order they were added.
+//
+// Example:
+//
+//	api.RegisterSpecGroupsIter(api.RegisteredSpecGroupsIter())
+func RegisterSpecGroupsIter(groups iter.Seq[RouteGroup]) {
+	if groups == nil {
+		return
+	}
+
 	specRegistry.mu.Lock()
 	defer specRegistry.mu.Unlock()
 
-	for _, group := range groups {
+	for group := range groups {
 		if group == nil {
 			continue
 		}

spec_registry_test.go

@@ -3,6 +3,7 @@
 package api_test
 
 import (
+	"iter"
 	"testing"
 
 	"github.com/gin-gonic/gin"
@@ -75,3 +76,37 @@ func TestRegisterSpecGroups_Good_IteratorReturnsSnapshot(t *testing.T) {
 		t.Fatalf("expected iterator snapshot to preserve alpha at /alpha, got %s at %s", groups[0].Name(), groups[0].BasePath())
 	}
 }
+
+func TestRegisterSpecGroupsIter_Good_DeduplicatesAndRegisters(t *testing.T) {
+	snapshot := api.RegisteredSpecGroups()
+	api.ResetSpecGroups()
+	t.Cleanup(func() {
+		api.ResetSpecGroups()
+		api.RegisterSpecGroups(snapshot...)
+	})
+
+	first := &specRegistryStubGroup{name: "alpha", basePath: "/alpha"}
+	second := &specRegistryStubGroup{name: "alpha", basePath: "/alpha"}
+	third := &specRegistryStubGroup{name: "gamma", basePath: "/gamma"}
+
+	groups := iter.Seq[api.RouteGroup](func(yield func(api.RouteGroup) bool) {
+		for _, group := range []api.RouteGroup{first, second, nil, third, first} {
+			if !yield(group) {
+				return
+			}
+		}
+	})
+
+	api.RegisterSpecGroupsIter(groups)
+
+	registered := api.RegisteredSpecGroups()
+	if len(registered) != 2 {
+		t.Fatalf("expected 2 unique groups, got %d", len(registered))
+	}
+	if registered[0].Name() != "alpha" || registered[0].BasePath() != "/alpha" {
+		t.Fatalf("expected first group to be alpha at /alpha, got %s at %s", registered[0].Name(), registered[0].BasePath())
+	}
+	if registered[1].Name() != "gamma" || registered[1].BasePath() != "/gamma" {
+		t.Fatalf("expected second group to be gamma at /gamma, got %s at %s", registered[1].Name(), registered[1].BasePath())
+	}
+}