fix: dataset layout data/<tier>/<seed>, mix tests, cli hardening

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

src/bench/cli.ts

@@ -15,7 +15,10 @@ function parseSeeds(s: string): number[] {
 
 function arg(args: string[], name: string, def: string): string {
   const i = args.indexOf(`--${name}`);
-  return i >= 0 && args[i + 1] ? args[i + 1]! : def;
+  if (i < 0) return def;
+  const v = args[i + 1];
+  if (v === undefined || v.startsWith("--")) throw new Error(`missing value for --${name}`);
+  return v;
 }
 
 async function main() {
@@ -23,7 +26,7 @@ async function main() {
   switch (cmd) {
     case "gen": {
       const tiers = arg(rest, "tiers", "t1a,t1b,t1c,t1d").split(",") as TierId[];
-      for (const t of tiers) if (!(t in TIERS)) throw new Error(`unknown tier: ${t}`);
+      for (const t of tiers) if (!Object.hasOwn(TIERS, t)) throw new Error(`unknown tier: ${t}`);
       const seeds = parseSeeds(arg(rest, "seeds", "1-5"));
       const root = arg(rest, "root", "data");
       for (const t of tiers) for (const s of seeds) {

src/bench/dataset.ts

@@ -10,16 +10,16 @@ import { mixStemsScaled } from "../audio/mix.ts";
 import { readWav, writeWav } from "../audio/wav.ts";
 import { encodeMp3 } from "../audio/mp3.ts";
 
-const SF2_PATH = "node_modules/@coderline/alphatab/dist/soundfont/sonivox.sf2";
+const SF2_PATH = join(import.meta.dir, "../../node_modules/@coderline/alphatab/dist/soundfont/sonivox.sf2");
 const SR = 44100;
 
 /**
- * Build one song into `<root>/<tier>-<seed>/`. Idempotent: skipped when mix.mp3 exists and song.json matches.
+ * Build one song into `<root>/<tier>/<seed>/`. Idempotent: skipped when mix.mp3 exists and song.json matches.
  * stems/<track>.wav are exactly each track's contribution to mix.wav (post-fx, post-pan, gain, normalisation),
  * so the stems sum to the mix up to PCM16 rounding.
  */
 export async function buildSong(tier: TierId, seed: number, root = "data"): Promise<string> {
-  const dir = join(root, `${tier}-${seed}`);
+  const dir = join(root, tier, String(seed));
   const song = generateSong(tier, seed);
   const songJson = JSON.stringify(song, null, 1);
   const jsonFile = Bun.file(join(dir, "song.json"));