The 3D board textures can be extracted as WebP: each player downloads about 4.7 MB less on a cold start (#186)

Only the extraction (tools/local-extract) and the manifest pointer change; no official textures are committed and nothing in play changes. Contributed by @Cloudnyco.

test/render/boardart.test.js

@@ -18,6 +18,7 @@ import { FX_KINDS, fxSpec, tilesAround } from '../../public/js/render/fx.js';
 import { statusIconKey } from '../../public/js/render/style.js';
 import { STATUS_KEYS } from '../../public/js/render/textures.js';
 import { createAssets, localAssetUrl } from '../../public/js/assets.js';
+import { loadBoardArt, resetBoardArt, sourceUrl } from '../../public/js/render/boardArt.js';
 
 const ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../..');
 const stages = JSON.parse(readFileSync(path.join(ROOT, 'data/stages.json'), 'utf8'));
@@ -311,4 +312,26 @@ describe('local-art manifest helpers', () => {
     const broken = createAssets({ manifest: {}, fetch: async () => { throw new Error('offline'); } });
     assert.equal(await broken.local(), null);
   });
+
+  test('board art loads the crop-table textures at the URLs the manifest lists (one download with the 3D board)', async () => {
+    const at = (n, ext) => `/assets/local/map/autochess/${n}.${ext}`;
+    const m = { groups: { 'map/autochess': { TX_autochessi_D: { path: at('TX_autochessi_D', 'webp') }, TX_autochessi_BG: { path: at('TX_autochessi_BG', 'webp') } } } };
+    const asked = [];
+    const store = { local: async () => m, localUrl: (g, n) => localAssetUrl(m, g, n), image: async (u) => { asked.push(u); return { width: 4 }; } };
+    assert.equal(sourceUrl(store, at('TX_autochessi_D', 'png')), at('TX_autochessi_D', 'webp'));
+    assert.equal(sourceUrl(store, at('TX_autochessi_common_D', 'png')), at('TX_autochessi_common_D', 'png'), 'not in the manifest: the table path');
+    assert.equal(sourceUrl({}, '/x/y.png'), '/x/y.png');
+    const tiles = { version: 2, materials: {}, source: { D: { path: at('TX_autochessi_D', 'png') }, common: { path: at('TX_autochessi_common_D', 'png') }, BG: { path: at('TX_autochessi_BG', 'png') } } };
+    const realFetch = globalThis.fetch;
+    globalThis.fetch = async (u) => (u === '/assets/local/map/autochess/tiles.json' ? { ok: true, json: async () => tiles } : { ok: false, status: 404 });
+    try {
+      resetBoardArt();
+      const art = await loadBoardArt(store);
+      assert.ok(art?.images.D && art.images.common && art.images.BG);
+      assert.deepEqual(asked.sort(), [at('TX_autochessi_BG', 'webp'), at('TX_autochessi_D', 'webp'), at('TX_autochessi_common_D', 'png')]);
+    } finally {
+      globalThis.fetch = realFetch;
+      resetBoardArt();
+    }
+  });
 });