feat: Added an .undo command to the REPL to let users have more control over the conversation

src/repl/mod.rs

@@ -52,7 +52,7 @@ pub const DEFAULT_CONTINUATION_PROMPT: &str = indoc! {"
     4. Continue with the next pending item now. Call tools immediately."
 };
 
-static REPL_COMMANDS: LazyLock<[ReplCommand; 50]> = LazyLock::new(|| {
+static REPL_COMMANDS: LazyLock<[ReplCommand; 51]> = LazyLock::new(|| {
     [
         ReplCommand::new(".help", "Show this help guide", AssertState::pass()),
         ReplCommand::new(".info", "Show system info", AssertState::pass()),
@@ -125,6 +125,11 @@ static REPL_COMMANDS: LazyLock<[ReplCommand; 50]> = LazyLock::new(|| {
             "Clear session messages",
             AssertState::True(StateFlags::SESSION),
         ),
+        ReplCommand::new(
+            ".undo",
+            "Undo the last exchange and restore the prompt",
+            AssertState::True(StateFlags::SESSION),
+        ),
         ReplCommand::new(
             ".compress session",
             "Compress session messages",
@@ -390,6 +395,10 @@ Type ".help" for additional help.
                             if exit {
                                 break;
                             }
+                            if let Some(text) = self.ctx.write().pending_prefill.take() {
+                                self.editor
+                                    .run_edit_commands(&[EditCommand::InsertString(text)]);
+                            }
                         }
                         Err(err) => {
                             render_error(err);
@@ -966,6 +975,9 @@ pub async fn run_repl_command(
                     println!(r#"Usage: .empty session"#)
                 }
             },
+            ".undo" => {
+                ctx.undo_last_exchange()?;
+            }
             ".rebuild" => match args {
                 Some("rag") => {
                     ctx.rebuild_rag(abort_signal.clone()).await?;