Add HyperFrames skills

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011h6NB8JQtfPc6eRCefEzBB

.agents/skills/media-use/audio/scripts/lib/python.mjs

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+// python.mjs — resolve which Python 3 executable to spawn, per platform.
+//
+// The audio engine (tts.mjs, bgm.mjs) shells out to `python3` for ElevenLabs
+// TTS and the local Lyria/MusicGen BGM paths. `python3` is the right name on
+// macOS/Linux, but on Windows the python.org installer only creates
+// `python.exe` plus the `py` launcher — there is no `python3.exe` (only the
+// Microsoft Store build adds one). So a bare `spawn("python3", …)` ENOENTs on a
+// standard Windows Python install, silently disabling every Python-backed audio
+// feature until the user hand-creates a `python3.exe` shim (reported twice).
+//
+// Resolve once, per process: probe the platform's candidates in order and take
+// the first that actually runs. `py` is the launcher, so it needs a `-3` arg to
+// select Python 3 — hence candidates are argv PREFIXES, not bare names.
+//
+// `HYPERFRAMES_PYTHON` (the documented PEP 668 venv setup) wins over the PATH probe, matching
+// the CLI's `findPython()`; ignoring it made BGM silently disable itself (#4614).
+
+import { spawnSync } from "node:child_process";
+
+// Accept only an interpreter whose `--version` reports Python 3, as the CLI's
+// `validatePythonOverride()` does. Exit status alone would take a Python 2
+// `python` (or any executable that exits 0) that `doctor` rejects. Python 2
+// prints its version to stderr, so read both streams.
+export function defaultProbe(cmd, args) {
+  try {
+    const result = spawnSync(cmd, args, { encoding: "utf-8", timeout: 5000 });
+    return result.status === 0 && /Python 3/.test(`${result.stdout}${result.stderr}`);
+  } catch {
+    return false;
+  }
+}
+
+/**
+ * Pick the argv prefix that launches Python 3 on this platform.
+ * Returns e.g. `["python3"]`, `["python"]`, or `["py", "-3"]`.
+ *
+ * Pure except for `probe` (which runs `<cmd> … --version`); `platform`, `probe`
+ * and `env` are injectable so every branch is unit-testable without spawning.
+ * If nothing probes OK, falls back to the canonical name for the platform so
+ * the eventual spawn fails loudly exactly as it did before — never worse.
+ */
+export function resolvePythonCommand(
+  platform = process.platform,
+  probe = defaultProbe,
+  env = process.env,
+) {
+  const override = env.HYPERFRAMES_PYTHON;
+  if (override && probe(override, ["--version"])) return [override];
+  const candidates =
+    platform === "win32" ? [["python3"], ["python"], ["py", "-3"]] : [["python3"], ["python"]];
+  for (const prefix of candidates) {
+    if (probe(prefix[0], [...prefix.slice(1), "--version"])) return prefix;
+  }
+  return candidates[0];
+}
+
+let cached = null;
+
+/** Cached `resolvePythonCommand()` — probing spawns, so resolve at most once. */
+export function pythonCommand() {
+  if (!cached) cached = resolvePythonCommand();
+  return cached;
+}
+
+/**
+ * Build a `{ cmd, args }` for running Python 3 with `extraArgs`, using the
+ * resolved (or supplied) prefix. Keeps the launcher's `-3` (and any future
+ * prefix args) ahead of the caller's own arguments.
+ */
+export function pythonInvocation(extraArgs, prefix = pythonCommand()) {
+  return { cmd: prefix[0], args: [...prefix.slice(1), ...extraArgs] };
+}
+
+/** Test-only: clear the cached resolution so a test can re-probe. */
+export function _resetPythonCommandCacheForTests() {
+  cached = null;
+}