fix(forge_select): enter alternate screen to keep prompt visible (#3492)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: amitksingh1490

crates/forge_main/src/ui.rs

@@ -3251,9 +3251,10 @@ impl<A: API + ConsoleWriter + 'static, F: Fn(ForgeConfig) -> A + Send + Sync> UI
             server.wait_for_code().await?
         } else {
             // Prompt user to paste authorization code
-            let code = ForgeWidget::input("Paste the authorization code")
-                .prompt()?
-                .ok_or_else(|| anyhow::anyhow!("Authorization code input cancelled"))?;
+            let code =
+                ForgeWidget::input(format!("Paste the authorization code for {provider_id}"))
+                    .prompt()?
+                    .ok_or_else(|| anyhow::anyhow!("Authorization code input cancelled"))?;
 
             if code.trim().is_empty() {
                 anyhow::bail!("Authorization code cannot be empty");

crates/forge_select/src/input.rs

@@ -1,7 +1,9 @@
-use std::io::IsTerminal;
+use std::io::{self, IsTerminal};
 
 use anyhow::Result;
 use colored::Colorize;
+use crossterm::execute;
+use crossterm::terminal::{EnterAlternateScreen, LeaveAlternateScreen};
 use rustyline::DefaultEditor;
 use tracing::debug;
 
@@ -63,6 +65,13 @@ impl InputBuilder {
             return Ok(None);
         }
 
+        // Enter the alternate screen so that the prompt is always visible and
+        // cannot be scrolled out of the viewport. This fixes an issue in
+        // terminals like VS Code (xterm.js) where rustyline's per-keystroke
+        // redraw causes the viewport to jump back to the cursor position,
+        // scrolling the prompt out of view.
+        let _guard = AlternateScreenGuard::enter();
+
         let mut rl = DefaultEditor::new()?;
 
         // On Windows, rustyline miscounts ANSI escape bytes as visible characters,
@@ -103,6 +112,24 @@ impl InputBuilder {
     }
 }
 
+/// Guard that enters the terminal alternate screen on creation and exits it on
+/// drop. Failures are silently ignored — the alternate screen is a cosmetic
+/// best-effort fix for terminal viewport issues.
+struct AlternateScreenGuard;
+
+impl AlternateScreenGuard {
+    fn enter() -> Option<Self> {
+        execute!(io::stdout(), EnterAlternateScreen).ok()?;
+        Some(Self)
+    }
+}
+
+impl Drop for AlternateScreenGuard {
+    fn drop(&mut self) {
+        let _ = execute!(io::stdout(), LeaveAlternateScreen);
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use pretty_assertions::assert_eq;