1. Supports payload received ack sync for sender

2. Supports safe-to-disconnect check (no auto reconnect or auto resume transfer yet)

PiperOrigin-RevId: 517191691

connections/implementation/proto/offline_wire_formats.proto

@@ -125,6 +125,7 @@ message ConnectionResponseFrame {
   // means bt supports multiplex while 0x00 means not. Refer to ClientProxy.java
   // for the bit usages.
   optional int32 multiplex_socket_bitmask = 5;
+  optional int32 nearby_connections_version = 6;
 }
 
 message PayloadTransferFrame {
@@ -165,6 +166,7 @@ message PayloadTransferFrame {
       UNKNOWN_EVENT_TYPE = 0;
       PAYLOAD_ERROR = 1;
       PAYLOAD_CANCELED = 2;
+      PAYLOAD_RECEIVED_ACK = 3;
     }
 
     optional EventType event = 1;
@@ -296,7 +298,12 @@ message KeepAliveFrame {
 // in other situations to trigger a faster disconnection event than waiting for
 // socket closed on the remote side.
 message DisconnectionFrame {
-  // Empty on purpose.
+  // Apply safe-to-disconnect protocol if true.
+  optional bool request_safe_to_disconnect = 1;
+
+  // Ack of receiving Disconnection frame will be sent to the sender
+  // frame.
+  optional bool ack_safe_to_disconnect = 2;
 }
 
 // A paired key encryption packet sent between devices, contains signed data.

proto/connections_enums.proto

@@ -205,6 +205,12 @@ enum PayloadStatus {
 
   // The connection not encrypted yet.
   ENDPOINT_UNENCRYPTED = 9;
+
+  // The payload was stopped by the local client disconnection.
+  LOCAL_CLIENT_DISCONNECTION = 10;
+
+  // The payload was stopped by the remote client disconnection.
+  REMOTE_CLIENT_DISCONNECTION = 11;
 }
 
 // The bandwidth of the mediums.