ace-step + stable-audio-open: deploy music + SFX generation to irv-ml1

Two new audio-generation stacks alongside the TTS slate:

ace-step :8210 — Apache 2.0 music generation foundation model
(hybrid diffusion + LLM). Lyric-aware multi-minute songs. ~10-12 GB
VRAM during inference, A6000-pinned. Custom Dockerfile patches
upstream's torch/cu126 resolution bug (--extra-index-url cu126 was
falling back to pypi-default cu13 wheels, mismatching torchvision).

stable-audio-open :8211 — Stability AI 1.21B latent-diffusion SFX +
ambience. Up to 47s clips at 44.1 kHz. ~6 GB VRAM in fp16,
A6000-pinned. Custom FastAPI shim around diffusers' StableAudioPipeline
(no upstream HTTP server). Dockerfile pins torchsde explicitly —
diffusers doesn't pull it as a hard dep but
CosineDPMSolverMultistepScheduler needs it.

stacks/ace-step/.env.example

@@ -0,0 +1,47 @@
+# ACE-Step 1.5 stack tunables. Copy to `.env` on irv-ml1 before
+# deploying.
+
+# ── build pin ────────────────────────────────────────────────────────
+# SHA of ace-step/ACE-Step to build from. Use the FULL 40-char SHA —
+# docker buildx git source resolver rejects short hashes. `main` works
+# at first deploy; pin to a real SHA before any production cutover so
+# upstream commits don't surprise you on next rebuild.
+ACE_STEP_SHA=main
+
+# Local image tag — bump when you change build context to force a
+# fresh layer build.
+ACE_STEP_TAG=v1
+
+# ── network ──────────────────────────────────────────────────────────
+# Host port (container listens on 8000 internally — infer-api.py
+# hardcodes uvicorn.run(host=0.0.0.0, port=8000)).
+# Reservations on irv-ml1: 8188 ComfyUI, 8190 CosyVoice, 8191 Qwen3-TTS,
+# 8192 IndexTTS-2, 8193 Kokoro, 8194 VibeVoice, 8195 Fish, 8196
+# Chatterbox, 8197 Voxtral, 8765 Parakeet ASR. 8210 starts the
+# audio-generation block (music + SFX) so future TTS adds can keep
+# going from 8198+.
+ACE_STEP_PORT=8210
+ACE_STEP_BIND=0.0.0.0
+
+# ── runtime / GPU ────────────────────────────────────────────────────
+# GPU pinning. "0" = RTX 3090 (24 GB), "1" = RTX A6000 (48 GB).
+# A6000 (1) recommended — Fish s2-pro lives there at ~17 GB, and
+# ACE-Step adds ~10-12 GB during inference, leaving comfortable
+# headroom on the 48 GB card. The 3090 is full with the TTS slate.
+ACE_STEP_GPU_DEVICES=1
+
+# ── persistent storage on the host ───────────────────────────────────
+# Model checkpoints — primary spot for any manually-staged checkpoints.
+# ACE-Step's auto-download lands in HF_HOME (cache dir below).
+ACE_STEP_CHECKPOINTS_DIR=/worktank/ace-step/checkpoints
+
+# Generated audio output — clients can pull from here via the
+# returned file path in the /generate response.
+ACE_STEP_OUTPUTS_DIR=/worktank/ace-step/outputs
+
+# Application logs.
+ACE_STEP_LOGS_DIR=/worktank/ace-step/logs
+
+# HF cache — first start pulls the ACE-Step checkpoint (~5-10 GB)
+# into this dir. Persistent across container recreates.
+ACE_STEP_CACHE_DIR=/worktank/ace-step/hf_cache