feat(write-sprite): compose atlas image + UV-JSON + lock output

tests/write-sprite.test.js

@@ -0,0 +1,46 @@
+const { test } = require('node:test');
+const assert = require('node:assert');
+const fs = require('node:fs');
+const path = require('node:path');
+const os = require('node:os');
+const Jimp = require('jimp');
+const { writeSpriteOutputs, buildUvJson } = require('../src/write-sprite');
+
+test('buildUvJson: emits atlas_id + atlas_size + sprites table', () => {
+    const placed = [
+        { alias: 'bed1', x: 0,  y: 0, w: 64, h: 32, sourceFile: 'Bed1.png' },
+        { alias: 'sack', x: 64, y: 0, w: 32, h: 32, sourceFile: 'Sack.png' },
+    ];
+    const json = buildUvJson('tcbasics', 96, 32, placed);
+    const parsed = JSON.parse(json);
+    assert.strictEqual(parsed.atlas_id, 'tcbasics');
+    assert.deepStrictEqual(parsed.atlas_size, [96, 32]);
+    assert.strictEqual(parsed.sprites.bed1.x, 0);
+    assert.strictEqual(parsed.sprites.bed1.w, 64);
+    assert.strictEqual(parsed.sprites.bed1.source_file, 'Bed1.png');
+    assert.strictEqual(parsed.sprites.sack.x, 64);
+});
+
+test('writeSpriteOutputs: produces 3 files', async (t) => {
+    const tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'write-sprite-test-'));
+    t.after(() => fs.rmSync(tmp, { recursive: true, force: true }));
+
+    // Build a 2-sprite atlas in memory
+    const a = new Jimp(32, 32, 0xff0000ff);
+    const b = new Jimp(32, 32, 0x00ff00ff);
+    const placed = [
+        { alias: 'red',   x: 0,  y: 0, w: 32, h: 32, sourceFile: 'Red.png',   image: a, padPx: 0 },
+        { alias: 'green', x: 32, y: 0, w: 32, h: 32, sourceFile: 'Green.png', image: b, padPx: 0 },
+    ];
+    await writeSpriteOutputs({
+        atlasId: 'test',
+        outDir: tmp,
+        placed,
+        boundsW: 64,
+        boundsH: 32,
+        lock: { atlas_id: 'test', version: 1, aliases: ['red', 'green'], sources: { red: 'Red.png', green: 'Green.png' } },
+    });
+    assert.ok(fs.existsSync(path.join(tmp, 'test/sprites.diffuse.atlas.png')));
+    assert.ok(fs.existsSync(path.join(tmp, 'test/sprites.uv.json')));
+    assert.ok(fs.existsSync(path.join(tmp, 'test/sprites.atlas.lock.json')));
+});