feat(api): add iterator for spec registry

Adds RegisteredSpecGroupsIter so CLI consumers can range over a snapshot of the package-level spec registry without copying the slice manually.

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

spec_registry.go

@@ -2,7 +2,12 @@
 
 package api
 
-import "sync"
+import (
+	"iter"
+	"sync"
+
+	"slices"
+)
 
 // specRegistry stores RouteGroups that should be included in CLI-generated
 // OpenAPI documents. Packages can register their groups during init and the
@@ -49,6 +54,19 @@ func RegisteredSpecGroups() []RouteGroup {
 	return out
 }
 
+// RegisteredSpecGroupsIter returns an iterator over the route groups registered
+// for CLI-generated OpenAPI documents.
+//
+// The iterator snapshots the current registry contents so callers can range
+// over it without holding the registry lock.
+func RegisteredSpecGroupsIter() iter.Seq[RouteGroup] {
+	specRegistry.mu.RLock()
+	groups := slices.Clone(specRegistry.groups)
+	specRegistry.mu.RUnlock()
+
+	return slices.Values(groups)
+}
+
 // ResetSpecGroups clears the package-level spec registry.
 // It is primarily intended for tests that need to isolate global state.
 //

spec_registry_test.go

@@ -45,3 +45,33 @@ func TestRegisterSpecGroups_Good_DeduplicatesByIdentity(t *testing.T) {
 		t.Fatalf("expected second group to be beta at /beta, got %s at %s", groups[1].Name(), groups[1].BasePath())
 	}
 }
+
+func TestRegisterSpecGroups_Good_IteratorReturnsSnapshot(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: "beta", basePath: "/beta"}
+
+	api.RegisterSpecGroups(first)
+
+	iter := api.RegisteredSpecGroupsIter()
+
+	api.RegisterSpecGroups(second)
+
+	var groups []api.RouteGroup
+	for group := range iter {
+		groups = append(groups, group)
+	}
+
+	if len(groups) != 1 {
+		t.Fatalf("expected iterator snapshot to contain 1 group, got %d", len(groups))
+	}
+	if groups[0].Name() != "alpha" || groups[0].BasePath() != "/alpha" {
+		t.Fatalf("expected iterator snapshot to preserve alpha at /alpha, got %s at %s", groups[0].Name(), groups[0].BasePath())
+	}
+}