feat(tui): auto-fit the to-do strip to its step count

The top work strip rendered at a fixed persisted height regardless of
content: a two-step plan floated in a band of blank water, and a long
plan scrolled inside a short window (user request, 2026-07-23 session).

height() now fits the content — the selectable rows plus the pinned
progress receipt and the divider — and treats the persisted
work_surface_top_height as a cap rather than a fixed size, together
with the existing half-terminal cap. Drag-resizing the divider and the
settings key keep working; they now bound how tall the strip may grow.
The default cap rises from 3 to 8 so a typical plan is visible in full,
matching the requested ceiling, while short terminals still clamp to
half their height.

Verified: cargo test -p codewhale-tui --bin codewhale-tui —
work_surface 57/57 (new top_strip_auto_fits_step_count_up_to_caps
pins content-fit, cap-wins, short-terminal, and empty cases), tui::ui
625/625, settings 104/104.

crates/tui/src/settings.rs

@@ -448,7 +448,9 @@ impl Default for Settings {
             fancy_animations: true,
             ocean_treatment: "ombre".to_string(),
             work_surface_placement: "top".to_string(),
-            work_surface_top_height: 3,
+            // Cap, not fixed height: the top strip auto-fits its rows and
+            // only grows to this many lines (user request, 2026-07-23).
+            work_surface_top_height: 8,
             work_surface_side_width: 30,
             constrained_frame_rate: false,
             bracketed_paste: true,

crates/tui/src/tui/work_surface/mod.rs

@@ -493,6 +493,34 @@ mod tests {
         assert_eq!(app.work_surface.hitboxes[0].row_y, 1);
     }
 
+    #[test]
+    fn top_strip_auto_fits_step_count_up_to_caps() {
+        // Two steps: divider + progress receipt + 2 rows = 4 lines, not a
+        // fixed-height band of blank water.
+        let mut two_steps = app();
+        two_steps.work_surface.top_height = 8;
+        add_todos(&mut two_steps, 2);
+        assert_eq!(super::height(&mut two_steps, 100, 40, false), 4);
+
+        // Ten steps: content wants 12 lines, the default 8-line cap wins.
+        let mut ten_steps = app();
+        ten_steps.work_surface.top_height = 8;
+        add_todos(&mut ten_steps, 10);
+        assert_eq!(super::height(&mut ten_steps, 100, 40, false), 8);
+
+        // Short terminal: the half-terminal cap beats both content and the
+        // configured cap.
+        let mut short_terminal = app();
+        short_terminal.work_surface.top_height = 8;
+        add_todos(&mut short_terminal, 10);
+        assert_eq!(super::height(&mut short_terminal, 100, 12, false), 6);
+
+        // Nothing to show: no strip at all.
+        let mut empty = app();
+        empty.work_surface.top_height = 8;
+        assert_eq!(super::height(&mut empty, 100, 40, false), 0);
+    }
+
     #[test]
     fn minimum_top_surface_keeps_a_numbered_todo_selectable() {
         let mut app = app();

crates/tui/src/tui/work_surface/render.rs

@@ -55,10 +55,22 @@ pub fn height(app: &mut App, width: u16, terminal_height: u16, classic_shell: bo
     if app.work_surface.effective_placement != WorkSurfacePlacement::Top {
         return 0;
     }
+    // The strip auto-fits its content: the literal selectable list plus the
+    // pinned progress receipt and the divider row. `top_height` (drag-resize
+    // / settings) and half the terminal act as caps, so a two-step plan
+    // takes two rows while an eight-step plan grows to show all eight —
+    // never a fixed-height band of blank water.
     let terminal_cap = terminal_height
         .saturating_div(2)
         .clamp(super::model::TOP_HEIGHT_MIN, super::model::TOP_HEIGHT_MAX);
-    app.work_surface.top_height.min(terminal_cap)
+    let cap = app.work_surface.top_height.min(terminal_cap);
+    let selectable = rows.iter().filter(|row| row.selectable).count();
+    let progress = u16::from(top_todo_progress(app, &rows).is_some());
+    let desired = u16::try_from(selectable)
+        .unwrap_or(u16::MAX)
+        .saturating_add(progress)
+        .saturating_add(1);
+    desired.clamp(super::model::TOP_HEIGHT_MIN, cap)
 }
 
 /// Split the transcript slot for a side rail. Top placement consumes its own