feat: tui beta for collab (#9690)

https://github.com/user-attachments/assets/1ca07e7a-3d82-40da-a5b0-8ab2eef0bb69

codex-rs/tui/src/slash_command.rs

@@ -26,6 +26,7 @@ pub enum SlashCommand {
     Init,
     Compact,
     Collab,
+    Agent,
     // Undo,
     Diff,
     Mention,
@@ -60,6 +61,7 @@ impl SlashCommand {
             SlashCommand::Ps => "list background terminals",
             SlashCommand::Model => "choose what model and reasoning effort to use",
             SlashCommand::Collab => "change collaboration mode (experimental)",
+            SlashCommand::Agent => "switch the active agent thread",
             SlashCommand::Approvals => "choose what Codex can do without approval",
             SlashCommand::Permissions => "choose what Codex is allowed to do",
             SlashCommand::ElevateSandbox => "set up elevated agent sandbox",
@@ -105,6 +107,7 @@ impl SlashCommand {
             SlashCommand::Rollout => true,
             SlashCommand::TestApproval => true,
             SlashCommand::Collab => true,
+            SlashCommand::Agent => true,
         }
     }