Adds two zero-shot voice-cloning TTS engines requested in #498, both
opt-in and subprocess-isolated with their own dedicated venv — the same
pattern as IndexTTS-2. The dedicated venv is forced, not just chosen:
each upstream pins a transformers version that conflicts with the
parent's >=5.3 (MOSS-TTS-v1.5 ==5.0.0, dots.tts ==4.57.0), so they cannot
share the parent interpreter.
Because they use the clone+venv bootstrap (env var -> clone -> uv venv),
this touches no pyproject.toml / uv.lock / bun.lock — `uv sync
--all-extras` and Docker's `bun install --frozen-lockfile` are unchanged,
so main's CI/Docker matrix stays green.
Engines:
- moss-tts-v15: 8B, 31 langs, ~16 GB weights, 24 kHz. AutoModel/
AutoProcessor via trust_remote_code. gpu_compat=(cuda,cpu) — MPS is
undocumented/untested upstream so it is never claimed; on a Mac it runs
on CPU. Apache-2.0, no license gate.
- dots-tts: 2B, 24 langs, ~9 GB weights, 48 kHz. DotsTtsRuntime;
continuation cloning (prompt_audio_path+prompt_text). Upstream is
Linux/macOS-only, so is_available() gates it off cleanly on Windows
(cross-platform parity rule — it is opt-in, never a broken default).
Wiring: registered in _LAZY_REGISTRY + _INSTALL_HINTS. list_backends()
surfaces both as subprocess/[cuda,cpu]/available-until-installed; the
data-driven Settings engine picker needs no frontend change.
Tests (19, fail-before/pass-after): registry resolution, subprocess
marker, no-MPS gpu_compat, the Windows gate, not-installed honesty, and
the parent-side generate() kwarg arbitration. Existing engine suite still
55 passed / 5 skipped. Sidecar inference follows the upstream-documented
APIs but, like IndexTTS/Supertonic, can't be executed in CI without the
multi-GB model clones.
Docs (same-PR per docs-sync rule): README + README_CN engine tables, new
docs/engines/moss-tts-v15.md + dots-tts.md, disk-usage.md (torch-dedup
note), CHANGELOG.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
