SSH reconnect reliability (#19398)

Release Notes:

- SSH Remoting: Fix message reliability across restarts

---------

Co-authored-by: Nathan <nathan@zed.dev>

crates/proto/proto/zed.proto

@@ -12,6 +12,7 @@ message Envelope {
     uint32 id = 1;
     optional uint32 responding_to = 2;
     optional PeerId original_sender_id = 3;
+    optional uint32 ack_id = 266;
 
     oneof payload {
         Hello hello = 4;
@@ -295,7 +296,9 @@ message Envelope {
         OpenServerSettings open_server_settings = 263;
 
         GetPermalinkToLine get_permalink_to_line = 264;
-        GetPermalinkToLineResponse get_permalink_to_line_response = 265;  // current max
+        GetPermalinkToLineResponse get_permalink_to_line_response = 265;
+
+        FlushBufferedMessages flush_buffered_messages = 267;
     }
 
     reserved 87 to 88;
@@ -2521,3 +2524,6 @@ message GetPermalinkToLine {
 message GetPermalinkToLineResponse {
     string permalink = 1;
 }
+
+message FlushBufferedMessages {}
+message FlushBufferedMessagesResponse {}

crates/proto/src/macros.rs

@@ -32,6 +32,7 @@ macro_rules! messages {
                         responding_to,
                         original_sender_id,
                         payload: Some(envelope::Payload::$name(self)),
+                        ack_id: None,
                     }
                 }
 

crates/proto/src/proto.rs

@@ -372,6 +372,7 @@ messages!(
     (OpenServerSettings, Foreground),
     (GetPermalinkToLine, Foreground),
     (GetPermalinkToLineResponse, Foreground),
+    (FlushBufferedMessages, Foreground),
 );
 
 request_messages!(
@@ -498,6 +499,7 @@ request_messages!(
     (RemoveWorktree, Ack),
     (OpenServerSettings, OpenBufferResponse),
     (GetPermalinkToLine, GetPermalinkToLineResponse),
+    (FlushBufferedMessages, Ack),
 );
 
 entity_messages!(