Tilemaps are a new placeable asset type that is painted with autotiles in the scene view, with layers, brush, eraser and rectangle, and is drawn at runtime and in the export (#128)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/editor/state.ts

@@ -139,6 +139,19 @@ function pickIds(input: readonly string[], primary?: string): { ids: string[]; p
   return { ids, primary: primary && ids.includes(primary) ? primary : ids[ids.length - 1]! };
 }
 
+/**
+ * Select leaves the scene view as it is – the map is picked up and moved like any other object.
+ * The other three paint: brush the chosen autotile cell by cell, erase clears, rect fills the box
+ * a drag spans. Painting is a mode on purpose; a map one cannot move would be worse than a click.
+ */
+export type TilemapTool = 'select' | 'brush' | 'erase' | 'rect';
+
+export interface TilemapPaint {
+  tool: TilemapTool;
+  autotileId: string;
+  layerId: string;
+}
+
 export type EditorMode = 'edit' | 'play';
 export type SaveStatus = 'saved' | 'dirty' | 'saving' | 'error' | 'conflict';
 
@@ -184,6 +197,12 @@ export class EditorState {
   notice = '';
   /** Keys copied in the Animation tab (#102). Lives for the session, across animations and projects. */
   keyClipboard: KeyClipboard | null = null;
+  /**
+   * What the scene view paints a tilemap with (#128): the tool, the autotile and the layer it goes
+   * on. Editor state, not model state – like the picked tile of the Animation tab, it is a way of
+   * working rather than something the project remembers.
+   */
+  tilemapPaint: TilemapPaint = { tool: 'select', autotileId: '', layerId: '' };
   /** The real (saved) model and its undo stack while `project` is the play-mode copy. */
   private edit: { project: Project; commands: CommandStack } | null = null;
 
@@ -603,6 +622,12 @@ export class EditorState {
    * Shows `message` in the toolbar and, unless `quiet`, keeps it in the console panel. Quiet is
    * for the play status lines, which state a mode rather than report an event.
    */
+  /** Changes what the scene view paints with; the inspector marks it and the view repaints. */
+  setTilemapPaint(patch: Partial<TilemapPaint>): void {
+    this.tilemapPaint = { ...this.tilemapPaint, ...patch };
+    this.emit('selection');
+  }
+
   setNotice(message: string, level: NoticeLevel = 'info'): void {
     this.notice = message;
     if (message !== '' && level !== 'quiet') consoleLog.push(level, message);