feat: support in-memory authentication

client.go

@@ -24,7 +24,10 @@ const (
 	availabilityTTL        = 60 * time.Second
 )
 
-type Option func(*Client) error
+type ClientOption func(*Client) error
+
+// Option is kept as an alias for compatibility with existing callers.
+type Option = ClientOption
 
 // WithHTTPClient configures the HTTP transport used by the client.
 func WithHTTPClient(httpClient *http.Client) Option {
@@ -58,6 +61,7 @@ func WithQRWriter(writer io.Writer) Option {
 
 type Client struct {
 	authPath        string
+	authDataChanged func(AuthData) error
 	authMu          sync.RWMutex
 	authData        AuthData
 	loginMu         sync.Mutex
@@ -80,8 +84,34 @@ func NewClient(authPath string, options ...Option) (*Client, error) {
 	if err != nil {
 		return nil, err
 	}
+	client, err := newClient(options...)
+	if err != nil {
+		return nil, err
+	}
+	client.authPath = resolvedPath
+	if err := client.loadAuthData(); err != nil {
+		return nil, err
+	}
+	client.ensureIdentity()
+	return client, nil
+}
+
+// NewClientWithAuthData creates a client whose authentication state is kept in memory.
+// Zero AuthData is accepted for QR login; non-zero AuthData must be complete.
+func NewClientWithAuthData(authData AuthData, options ...ClientOption) (*Client, error) {
+	if !authData.zero() && !authData.complete() {
+		return nil, fmt.Errorf("incomplete auth data")
+	}
+	client, err := newClient(options...)
+	if err != nil {
+		return nil, err
+	}
+	client.setAuthData(authData)
+	return client, nil
+}
+
+func newClient(options ...ClientOption) (*Client, error) {
 	client := &Client{
-		authPath:        resolvedPath,
 		httpClient:      http.DefaultClient,
 		baseURL:         defaultBaseURL,
 		loginURL:        defaultLoginURL,
@@ -97,14 +127,22 @@ func NewClient(authPath string, options ...Option) (*Client, error) {
 			return nil, err
 		}
 	}
-	if err := client.loadAuthData(); err != nil {
-		return nil, err
-	}
-	client.ensureIdentity()
 	client.initSession()
 	return client, nil
 }
 
+// WithAuthDataChanged configures serialized persistence for in-memory auth updates.
+// The callback runs under login serialization, but never while the auth data lock is held.
+func WithAuthDataChanged(callback func(AuthData) error) ClientOption {
+	return func(client *Client) error {
+		if callback == nil {
+			return fmt.Errorf("auth data changed callback must not be nil")
+		}
+		client.authDataChanged = callback
+		return nil
+	}
+}
+
 func resolveAuthPath(authPath string) (string, error) {
 	if authPath == "" {
 		home, err := os.UserHomeDir()