feat(openapi): add info license metadata

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

openapi.go

@@ -11,6 +11,8 @@ import (
 )
 
 // SpecBuilder constructs an OpenAPI 3.1 specification from registered RouteGroups.
+// Title, Description, Version, and optional licence metadata populate the
+// OpenAPI info block.
 //
 // Example:
 //
@@ -21,6 +23,8 @@ type SpecBuilder struct {
 	Description string
 	Version     string
 	Servers     []string
+	LicenseName string
+	LicenseURL  string
 }
 
 // Build generates the complete OpenAPI 3.1 JSON spec.
@@ -47,6 +51,16 @@ func (sb *SpecBuilder) Build(groups []RouteGroup) ([]byte, error) {
 		},
 	}
 
+	if sb.LicenseName != "" {
+		license := map[string]any{
+			"name": sb.LicenseName,
+		}
+		if sb.LicenseURL != "" {
+			license["url"] = sb.LicenseURL
+		}
+		spec["info"].(map[string]any)["license"] = license
+	}
+
 	if servers := normaliseServers(sb.Servers); len(servers) > 0 {
 		out := make([]map[string]any, 0, len(servers))
 		for _, server := range servers {

openapi_test.go

@@ -146,6 +146,38 @@ func TestSpecBuilder_Good_EmptyGroups(t *testing.T) {
 	}
 }
 
+func TestSpecBuilder_Good_InfoIncludesLicenseMetadata(t *testing.T) {
+	sb := &api.SpecBuilder{
+		Title:       "Test",
+		Description: "Licensed test API",
+		Version:     "1.2.3",
+		LicenseName: "EUPL-1.2",
+		LicenseURL:  "https://eupl.eu/1.2/en/",
+	}
+
+	data, err := sb.Build(nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	var spec map[string]any
+	if err := json.Unmarshal(data, &spec); err != nil {
+		t.Fatalf("invalid JSON: %v", err)
+	}
+
+	info := spec["info"].(map[string]any)
+	license, ok := info["license"].(map[string]any)
+	if !ok {
+		t.Fatal("expected license metadata in spec info")
+	}
+	if license["name"] != "EUPL-1.2" {
+		t.Fatalf("expected license name EUPL-1.2, got %v", license["name"])
+	}
+	if license["url"] != "https://eupl.eu/1.2/en/" {
+		t.Fatalf("expected license url to be preserved, got %v", license["url"])
+	}
+}
+
 func TestSpecBuilder_Good_WithDescribableGroup(t *testing.T) {
 	sb := &api.SpecBuilder{
 		Title:       "Test",