Allow subscribing to pane viewport updates (renders) from the CLI (#4814)

* initial subscribe implementation

* tests for subscribe

* update cli help

* rustfmt

* add pr

2 files changed, 20 insertions, 0 deletions

diff --git a/zellij-utils/src/client_server_contract/client_to_server.proto b/zellij-utils/src/client_server_contract/client_to_server.proto
index 7d922e6d..8fdedac2 100644
--- a/zellij-utils/src/client_server_contract/client_to_server.proto
+++ b/zellij-utils/src/client_server_contract/client_to_server.proto
@@ -21,6 +21,7 @@ message ClientToServerMsg {
     WebServerStartedMsg web_server_started = 14;
     FailedToStartWebServerMsg failed_to_start_web_server = 15;
     AttachWatcherClientMsg attach_watcher_client = 16;
+    SubscribeToPaneRendersMsg subscribe_to_pane_renders = 17;
   }
 }
 
@@ -97,3 +98,8 @@ message WebServerStartedMsg {
 message FailedToStartWebServerMsg {
   string error = 1;
 }
+
+message SubscribeToPaneRendersMsg {
+  repeated PaneId pane_ids = 1;
+  optional uint32 scrollback = 2;
+}
diff --git a/zellij-utils/src/client_server_contract/server_to_client.proto b/zellij-utils/src/client_server_contract/server_to_client.proto
index 57813ebb..e0b8b529 100644
--- a/zellij-utils/src/client_server_contract/server_to_client.proto
+++ b/zellij-utils/src/client_server_contract/server_to_client.proto
@@ -18,6 +18,8 @@ message ServerToClientMsg {
     StartWebServerMsg start_web_server = 11;
     RenamedSessionMsg renamed_session = 12;
     ConfigFileUpdatedMsg config_file_updated = 13;
+    PaneRenderUpdateMsg pane_render_update = 14;
+    SubscribedPaneClosedMsg subscribed_pane_closed = 15;
   }
 }
 
@@ -74,3 +76,15 @@ message RenamedSessionMsg {
 message ConfigFileUpdatedMsg {
   // Empty message
 }
+
+message PaneRenderUpdateMsg {
+  PaneId pane_id = 1;
+  repeated string viewport = 2;
+  repeated string scrollback = 3;
+  bool has_scrollback = 4;
+  bool is_initial = 5;
+}
+
+message SubscribedPaneClosedMsg {
+  PaneId pane_id = 1;
+}