Research in the library: rooms, spells, towers, traps and doors are discovered in a fixed order

- studying creatures collect research points (mages and owls best, higher levels faster); studying gives less mana than before
- free play starts with the basics; campaign missions know what their story allows and can research what the next four missions would bring
- research shown in the top bar; the library's info lists the current item and what comes next; locked tools say whether they can be researched

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui.rs

@@ -327,6 +327,7 @@ pub struct Ui {
     minimap_tex: Texture2D,
     minimap_t: f64,
     minimap_rect: Rect,
+    pub last_locked: Option<usize>, // the locked tool clicked last
     end_buttons: Vec<(Rect, u8)>,
     goals_rect: Rect, // mission goals panel (click: briefing) // end dialog: 0 new game, 1 next/again, 2 campaign
     lang_rects: Vec<(Rect, String)>,
@@ -378,6 +379,7 @@ impl Ui {
             minimap_tex: tex,
             minimap_t: -1.0,
             minimap_rect: Rect::new(0.0, 0.0, 0.0, 0.0),
+            last_locked: None,
             end_buttons: Vec::new(),
             goals_rect: Rect::new(0.0, 0.0, 0.0, 0.0),
             lang_rects: Vec::new(),
@@ -433,7 +435,10 @@ impl Ui {
                     self.open_cat = None;
                     UiAction::OpenMenu
                 }
-                TBtn::Tool(i) if !g.tool_allowed(i) => UiAction::Locked,
+                TBtn::Tool(i) if !g.tool_allowed(i) => {
+                    self.last_locked = Some(i);
+                    UiAction::Locked
+                }
                 TBtn::Tool(i) => {
                     self.open_cat = None;
                     self.tip = Some((i, get_time()));
@@ -442,6 +447,7 @@ impl Ui {
                 TBtn::Cat(c) => {
                     let tools = CATS[c].1;
                     if tools.len() == 1 && !g.tool_allowed(tools[0]) {
+                        self.last_locked = Some(tools[0]);
                         UiAction::Locked
                     } else if tools.len() == 1 {
                         self.open_cat = None;
@@ -518,6 +524,11 @@ impl Ui {
             let left = (limit - g.time).max(0.0);
             segs.insert(0, vec![txt(tr("hud.time_left"), if left < 120.0 { RED } else { GOLD }), Part::Gap, txt(mmss(left), TXT)]);
         }
+        if let Some(k) = g.research_target().filter(|_| g.counts[4] > 0) {
+            let (tool, cost) = crate::research::RESEARCH[k];
+            let name: String = tool_info(TOOLS[tool]).name.chars().take(18).collect();
+            segs.push(vec![txt(tr("hud.research"), BLUE), Part::Gap, txt(name, TXT), Part::Gap, Part::Bar(g.research / cost, BLUE)]);
+        }
         segs.push(vec![txt(tr("hud.payday"), if g.payday <= PAYDAY_WARN { RED } else { GOLD }), Part::Gap, txt(mmss(g.payday), TXT)]);
         segs.push(vec![txt(tr("hud.army"), TXT), Part::Gap, txt((g.army_value() as i32).to_string(), TXT)]);
         if !g.hand.is_empty() {
@@ -1215,6 +1226,21 @@ pub fn hover_info(g: &Game, ent: Option<usize>, tile: Option<(i32, i32)>) -> Vec
                 out.push((tr(ROOM_NAMES[r]), FRAME_HI));
                 match k {
                     Kind::Farm => out.push((trf("farm.food", &[(t.food as i32).to_string()]), GREEN)),
+                    Kind::Library => {
+                        let q = g.research_queue(4);
+                        if q.is_empty() {
+                            out.push((tr("research.done"), DIM));
+                        }
+                        for (n, k) in q.iter().enumerate() {
+                            let (tool, cost) = crate::research::RESEARCH[*k];
+                            let name = tool_info(TOOLS[tool]).name;
+                            if n == 0 {
+                                out.push((trf("research.now", &[name, ((g.research / cost * 100.0).min(99.0) as i32).to_string()]), BLUE));
+                            } else {
+                                out.push((trf("research.next", &[name]), DIM));
+                            }
+                        }
+                    }
                     Kind::Treasury if t.gold > 0 => {
                         let what = ["res.gold", "res.silver", "res.ruby", "res.diamond"][(t.res & 3) as usize];
                         out.push((trf("treasury.content", &[t.gold.to_string(), tr(what)]), GOLD));