palette changes

kiln-core/src/layer.rs

@@ -43,6 +43,9 @@ pub(crate) struct Layer {
 ///   layer of identical floor).
 /// - `sparse` — a list of `{ x, y, ch }` cells over an otherwise all-spaces grid
 ///   (handy for a layer holding just a few objects).
+///
+/// A space (`' '`) is always a transparent empty cell and is never a palette key
+/// (any `" "` entry in `palette` is ignored).
 #[derive(Deserialize, Serialize)]
 pub(crate) struct LayerData {
     /// Multi-line grid string; one char per cell, looked up in `palette`.
@@ -341,12 +344,14 @@ pub(crate) fn build_layer(
     errors: &mut Vec<LogLine>,
 ) -> Result<(Layer, Vec<Placement>), String> {
     // Resolve each palette entry once (per-cell work like generators happens below).
+    // Space is always a transparent empty cell, so it is never a palette key — any
+    // `" "` entry is ignored.
     let resolved: HashMap<char, Resolved> = data
         .palette
         .iter()
-        .map(|(key, entry)| {
+        .filter_map(|(key, entry)| {
             let ch = key.chars().next().unwrap_or(' ');
-            (ch, resolve_entry(ch, entry, errors))
+            (ch != ' ').then(|| (ch, resolve_entry(ch, entry, errors)))
         })
         .collect();
 
@@ -358,6 +363,11 @@ pub(crate) fn build_layer(
     let mut placements: Vec<Placement> = Vec::new();
     for (y, row) in grid.iter().enumerate() {
         for (x, &ch) in row.iter().enumerate() {
+            // A space is always a transparent empty cell, palette or not.
+            if ch == ' ' {
+                cells.push((Glyph::transparent(), Archetype::Empty));
+                continue;
+            }
             match resolved.get(&ch) {
                 Some(Resolved::Cell(g, a)) => cells.push((*g, *a)),
                 Some(Resolved::FloorGen(g)) => cells.push((g.generate(rng), Archetype::Empty)),