playtest mode

kiln-tui/src/main.rs

@@ -195,6 +195,9 @@ fn run(terminal: &mut ratatui::DefaultTerminal, mode: &mut Mode, ui: &mut Ui) ->
         // Apply any Play↔Edit switch a menu action requested this frame.
         apply_pending_mode(mode, ui);
 
+        // Enter/leave a playtest if the editor or a playtest Esc requested it.
+        apply_playtest_transition(mode, ui);
+
         // A menu action may have set should_quit; exit once any close animation finishes.
         if ui.should_quit && ui.active_animation.is_none() {
             return Ok(());
@@ -229,6 +232,40 @@ fn apply_pending_mode(mode: &mut Mode, ui: &mut Ui) {
     }
 }
 
+/// Applies a pending **playtest** enter or exit, swapping the top-level [`Mode`].
+///
+/// Entering: the editor parked a built [`GameState`] in
+/// [`EditorState::pending_playtest`]; swap to [`Mode::Play`] and stash the editor in
+/// [`Ui::suspended_editor`] so `Esc` can restore it. Taking the option first drops the
+/// `&mut EditorState` borrow before [`std::mem::replace`], whose return value hands us
+/// the old `Mode::Edit` (so the editor is preserved with no placeholder variant).
+///
+/// Exiting (`Esc` during a playtest set [`Ui::exit_playtest`]): drop the playtest game
+/// and restore the suspended editor verbatim. The deep-copied playtest world is simply
+/// dropped, so the editor's own boards were never touched.
+fn apply_playtest_transition(mode: &mut Mode, ui: &mut Ui) {
+    // Enter: take the parked game (this ends the editor borrow before the swap).
+    let new_game = if let Mode::Edit(ed) = mode {
+        ed.pending_playtest.take()
+    } else {
+        None
+    };
+    if let Some(game) = new_game {
+        let old = std::mem::replace(mode, Mode::Play(game));
+        if let Mode::Edit(editor) = old {
+            ui.suspended_editor = Some(editor);
+        }
+    }
+
+    // Exit: restore the parked editor, dropping the playtest game.
+    if ui.exit_playtest {
+        ui.exit_playtest = false;
+        if let Some(editor) = ui.suspended_editor.take() {
+            *mode = Mode::Edit(editor);
+        }
+    }
+}
+
 /// Render a single frame for the active [`Mode`], then the overlay layer on top.
 ///
 /// The body of the frame is either the play view ([`draw_play`]) or the editor
@@ -286,6 +323,13 @@ fn draw_play(frame: &mut Frame, game: &GameState, ui: &mut Ui) {
     // Borrow the board for the duration of the frame (no script runs during draw).
     let board = &game.board();
 
+    // A playtest (launched from the editor) marks its title so it's distinct from play.
+    let title = if ui.suspended_editor.is_some() {
+        format!(" {} (playtest) ", board.name)
+    } else {
+        format!(" {} ", board.name)
+    };
+
     if ui.log.open {
         // Split the screen: board on top, log panel of `height` at the bottom.
         let [board_area, log_area] =
@@ -294,7 +338,7 @@ fn draw_play(frame: &mut Frame, game: &GameState, ui: &mut Ui) {
                 .areas(frame.area());
 
         let block = Block::bordered()
-            .title(format!(" {} ", board.name))
+            .title(title)
             .merge_borders(MergeStrategy::Exact);
         let inner = block.inner(board_area);
         frame.render_widget(block, board_area);
@@ -302,7 +346,7 @@ fn draw_play(frame: &mut Frame, game: &GameState, ui: &mut Ui) {
         frame.render_stateful_widget(LogWidget::new(&game.log), log_area, &mut ui.log);
     } else {
         // Panel closed: board fills the screen, latest message in the border.
-        let mut block = Block::bordered().title(format!(" {} ", board.name));
+        let mut block = Block::bordered().title(title);
         block = block.title_bottom(log_preview_line(&game.log).left_aligned());
         let inner = block.inner(frame.area());
         frame.render_widget(block, frame.area());