diff --git a/mobile/unibus.go b/mobile/unibus.go
new file mode 100644
index 0000000..d2a6a9c
--- /dev/null
+++ b/mobile/unibus.go
@@ -0,0 +1,108 @@
+// Package mobile exposes a flat, gomobile-friendly API over the unibus client
+// so an Android app can join rooms, publish, and receive messages with the same
+// end-to-end encryption as any native Go peer.
+//
+// gomobile only supports a limited set of types across the binding boundary
+// (string, []byte, int, bool, error, named structs, and interfaces). This layer
+// translates the richer client API into those primitives and delivers incoming
+// frames through a Java/Kotlin-implemented FrameListener callback. No protocol
+// or cryptography is reimplemented here: every call delegates to pkg/client,
+// which is the single source of truth shared with every other peer on the bus.
+package mobile
+
+import (
+	"time"
+
+	"github.com/enmanuel/unibus/pkg/client"
+	"github.com/enmanuel/unibus/pkg/frame"
+	"github.com/enmanuel/unibus/pkg/room"
+)
+
+// FrameListener receives decrypted messages for a subscribed room. The Android
+// side implements this interface. Its methods are invoked from a NATS delivery
+// goroutine, so implementations must hop back to the UI thread (for example via
+// a coroutine on the main dispatcher) before touching Android views.
+type FrameListener interface {
+	OnFrame(roomID string, sender string, msgID string, text string)
+}
+
+// Session is a connected unibus peer. Create it with NewSession and close it
+// with Close when the app stops.
+type Session struct {
+	c *client.Client
+}
+
+// GenerateIdentity creates (or loads) the long-term keypair stored at path.
+// Call it once on first launch. The resulting file holds the peer's private
+// Ed25519 and X25519 keys and must be kept private to the app sandbox.
+func GenerateIdentity(path string) error {
+	_, err := client.LoadOrCreateIdentity(path)
+	return err
+}
+
+// NewSession loads the identity at idPath and connects to the bus. natsURL is
+// the data plane (for example nats://host:4250) and ctrlURL is the control
+// plane HTTP endpoint (for example http://host:8470).
+func NewSession(idPath, natsURL, ctrlURL string) (*Session, error) {
+	id, err := client.LoadOrCreateIdentity(idPath)
+	if err != nil {
+		return nil, err
+	}
+	c, err := client.New(natsURL, ctrlURL, id)
+	if err != nil {
+		return nil, err
+	}
+	return &Session{c: c}, nil
+}
+
+// EndpointID returns this peer's stable endpoint identifier, derived from its
+// signing public key. It is the value that appears as the sender of frames.
+func (s *Session) EndpointID() string {
+	return s.c.Endpoint().ID
+}
+
+// CreateRoom opens a room on the given subject. mode is "matrix" for the
+// encrypted, persisted and signed policy, or "nats" for plain cleartext. It
+// returns the room id used by Join, Publish and Subscribe.
+func (s *Session) CreateRoom(subject, mode string) (string, error) {
+	p := room.ModeNATS
+	if mode == "matrix" {
+		p = room.ModeMatrix
+	}
+	return s.c.CreateRoom(subject, p)
+}
+
+// Join fetches the room key when the room is encrypted and prepares the session
+// to publish to and receive from the room.
+func (s *Session) Join(roomID string) error {
+	return s.c.Join(roomID)
+}
+
+// Publish sends a UTF-8 text message to the room.
+func (s *Session) Publish(roomID, text string) error {
+	return s.c.Publish(roomID, []byte(text))
+}
+
+// Subscribe streams decrypted messages of the room to the listener until the
+// session is closed.
+func (s *Session) Subscribe(roomID string, l FrameListener) error {
+	_, err := s.c.Subscribe(roomID, func(f frame.Frame, plaintext []byte) {
+		l.OnFrame(roomID, f.Sender, f.MsgID, string(plaintext))
+	})
+	return err
+}
+
+// Request performs an RPC request/reply against subject and returns the reply
+// payload as text. timeoutMs bounds the wait in milliseconds.
+func (s *Session) Request(subject, text string, timeoutMs int) (string, error) {
+	out, err := s.c.Request(subject, []byte(text), time.Duration(timeoutMs)*time.Millisecond)
+	if err != nil {
+		return "", err
+	}
+	return string(out), nil
+}
+
+// Close disconnects the peer from the bus.
+func (s *Session) Close() error {
+	return s.c.Close()
+}