feat: expose CreateRoom in pkg/olcrtc public API

Add olcrtc.CreateRoom(ctx, authName) that delegates to the auth
provider's RoomCreator interface. Returns ErrRoomCreationUnsupported
for providers that don't support room creation (e.g. telemost).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pkg/olcrtc/olcrtc.go

@@ -43,6 +43,8 @@ var (
 	ErrURLRequired = errors.New("olcrtc: URL required when using direct engine mode")
 	// ErrTokenRequired is returned when direct mode is used without a token.
 	ErrTokenRequired = errors.New("olcrtc: Token required when using direct engine mode")
+	// ErrRoomCreationUnsupported is returned when the auth provider cannot create rooms.
+	ErrRoomCreationUnsupported = errors.New("olcrtc: auth provider does not support room creation")
 )
 
 // Config is the input to [New].
@@ -228,3 +230,23 @@ func (s *Session) SetEndedCallback(cb func(reason string)) {
 func (s *Session) SetShouldReconnect(fn func() bool) {
 	s.inner.SetShouldReconnect(fn)
 }
+
+// CreateRoom creates a new room via the auth provider and returns the room ID.
+// Only works when the session was created with Auth set to a provider that
+// supports room creation (wbstream, jazz). Returns [ErrRoomCreationUnsupported]
+// for providers that don't support it (e.g. telemost).
+func CreateRoom(ctx context.Context, authName string) (string, error) {
+	p, err := auth.Get(authName)
+	if err != nil {
+		return "", fmt.Errorf("olcrtc: auth provider %q not registered: %w", authName, err)
+	}
+	creator, ok := p.(auth.RoomCreator)
+	if !ok {
+		return "", fmt.Errorf("%w: %s", ErrRoomCreationUnsupported, authName)
+	}
+	roomID, err := creator.CreateRoom(ctx, auth.Config{})
+	if err != nil {
+		return "", fmt.Errorf("olcrtc: create room: %w", err)
+	}
+	return roomID, nil
+}

pkg/olcrtc/olcrtc_test.go

@@ -60,11 +60,22 @@ func (a stubAuth) Issue(_ context.Context, cfg auth.Config) (auth.Credentials, e
 	return auth.Credentials{URL: "wss://stub/", Token: stubToken}, nil
 }
 
+type stubAuthWithRoomCreator struct{ stubAuth }
+
+func (stubAuthWithRoomCreator) CreateRoom(_ context.Context, _ auth.Config) (string, error) {
+	return "created-room-id", nil
+}
+
 func registerStubAuth(t *testing.T, name, engineName string) {
 	t.Helper()
 	auth.Register(name, stubAuth{engineName: engineName})
 }
 
+func registerStubAuthWithCreator(t *testing.T, name, engineName string) {
+	t.Helper()
+	auth.Register(name, stubAuthWithRoomCreator{stubAuth{engineName: engineName}})
+}
+
 // --- tests ---
 
 func TestNewDirect_MissingURL(t *testing.T) {
@@ -159,6 +170,28 @@ func TestRegisterDefaults_Idempotent(_ *testing.T) {
 	olcrtc.RegisterDefaults()
 }
 
+func TestCreateRoom_Unsupported(t *testing.T) {
+	registerStubAuth(t, "stub-nocreate", "stub-direct")
+
+	_, err := olcrtc.CreateRoom(context.Background(), "stub-nocreate")
+	if !errors.Is(err, olcrtc.ErrRoomCreationUnsupported) {
+		t.Fatalf("CreateRoom(no creator) = %v, want ErrRoomCreationUnsupported", err)
+	}
+}
+
+func TestCreateRoom_OK(t *testing.T) {
+	registerStubEngine(t, "stub-creator-engine")
+	registerStubAuthWithCreator(t, "stub-creator", "stub-creator-engine")
+
+	roomID, err := olcrtc.CreateRoom(context.Background(), "stub-creator")
+	if err != nil {
+		t.Fatalf("CreateRoom() error = %v", err)
+	}
+	if roomID == "" {
+		t.Fatal("CreateRoom() returned empty room ID")
+	}
+}
+
 func TestDial_RoundTrip(t *testing.T) {
 	registerStubEngine(t, "stub-dial")