Add HyperFrames skills (from heygen-com/hyperframes, Apache-2.0)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FXVsD1DgdzZLiPuwtKzMSY

.claude/skills/media-use/audio/scripts/lib/bgm.test.mjs

@@ -0,0 +1,74 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { existsSync, mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { appendRecord } from "../../../scripts/lib/manifest.mjs";
+import {
+  BGM_BED_VOLUME,
+  BGM_SILENT_VOLUME,
+  bgmDefaultVolume,
+  generateBgmDetached,
+} from "./bgm.mjs";
+
+// Regression: narrated pipelines used to ship BGM at 0.8 (≈ -2 dB), ~16 dB
+// hotter than a music bed under a voice should be. The default under narration
+// must be a proper bed (≈ -18 dB); a silent film keeps the louder default.
+
+const dbfs = (linear) => 20 * Math.log10(linear);
+
+test("BGM under narration is a bed near -18 dB", () => {
+  assert.equal(bgmDefaultVolume(true), BGM_BED_VOLUME);
+  assert.equal(BGM_BED_VOLUME, 0.12);
+  const db = dbfs(BGM_BED_VOLUME);
+  assert.ok(db < -17 && db > -19, `bed should be ≈ -18 dB, got ${db.toFixed(1)} dB`);
+});
+
+test("a silent film (no voice) keeps BGM forward", () => {
+  assert.equal(bgmDefaultVolume(false), BGM_SILENT_VOLUME);
+  assert.equal(BGM_SILENT_VOLUME, 0.9);
+});
+
+test("the narrated default is well below the voice (≈ 0 dBFS)", () => {
+  // Voice sits at data-volume="1" (0 dBFS); the bed must be ~16+ dB under it.
+  const separation = dbfs(1) - dbfs(bgmDefaultVolume(true));
+  assert.ok(
+    separation >= 16,
+    `bed should sit ≥16 dB under the voice, got ${separation.toFixed(1)} dB`,
+  );
+});
+
+test(
+  "generating music again clears the engine's old track, so waiting cannot mistake it for the new one",
+  { skip: process.platform === "win32" && "the fake python is a shell script" },
+  (t) => {
+    const dir = mkdtempSync(join(tmpdir(), "hf-bgm-"));
+    const path = process.env.PATH;
+    t.after(() => {
+      process.env.PATH = path;
+      rmSync(dir, { recursive: true, force: true });
+    });
+    mkdirSync(join(dir, "bin"));
+    for (const name of ["python3", "python"])
+      writeFileSync(join(dir, "bin", name), "#!/bin/sh\nexit 0\n", { mode: 0o755 });
+    process.env.PATH = `${join(dir, "bin")}:${path}`;
+    mkdirSync(join(dir, "assets/bgm"), { recursive: true });
+    writeFileSync(join(dir, "assets/bgm/track.wav"), "last run's track");
+    appendRecord(dir, {
+      id: "bgm_001",
+      type: "bgm",
+      path: "assets/bgm/track.wav",
+      source: "generated",
+    });
+
+    const gen = generateBgmDetached({
+      prompt: "calm",
+      durationS: 5,
+      hyperframesDir: dir,
+      anomalies: [],
+    });
+
+    assert.equal(gen.path, "assets/bgm/track.wav");
+    assert.equal(existsSync(join(dir, "assets/bgm/track.wav")), false);
+  },
+);