diff --git a/src/sharer.rs b/src/sharer.rs
index 513e4a5..3b122ed 100644
--- a/src/sharer.rs
+++ b/src/sharer.rs
@@ -579,6 +579,11 @@ pub enum UpstreamMessage {
 
     /// The sharer removed a pending user as a session guest.
     RemovePendingGuest { email: String },
+
+    /// The sharer's environment setup (repo clone, setup commands, MCP
+    /// discovery, skill loading) has completed. Viewers use this to
+    /// transition out of the setup-commands UI phase.
+    EnvironmentSetupComplete,
 }
 
 impl UpstreamMessage {
diff --git a/src/viewer.rs b/src/viewer.rs
index 16fbfd2..90052ae 100644
--- a/src/viewer.rs
+++ b/src/viewer.rs
@@ -259,6 +259,10 @@ pub enum DownstreamMessage {
     /// A response to a [`UpstreamMessage::Ping`].
     /// Used to demonstrate that the server is still alive.
     Pong { data: Vec<u8> },
+
+    /// The sharer's environment setup has completed. Viewers use this to
+    /// transition out of the setup-commands UI phase.
+    EnvironmentSetupComplete,
 }
 
 impl DownstreamMessage {