diff --git a/stacks/chatterbox-fast/.env.example b/stacks/chatterbox-fast/.env.example
new file mode 100644
index 0000000..7b628a7
--- /dev/null
+++ b/stacks/chatterbox-fast/.env.example
@@ -0,0 +1,47 @@
+# chatterbox-fast stack tunables. Copy to `.env` on irv-ml1 before deploying.
+
+# ── image / build ────────────────────────────────────────────────────
+# Local image tag for this stack. Bump to force a fresh layer build.
+CBF_TAG=v1
+
+# Base image tag — the sibling `chatterbox` stack's local image, which
+# carries the chatterbox lib + torch + fastapi. Must exist on irv-ml1
+# (built by the `chatterbox` stack). Bump in lockstep if that rebuilds.
+CBF_BASE_TAG=v1
+
+# ── network ──────────────────────────────────────────────────────────
+# Host port. Container listens on 8197 internally.
+# Reserved on irv-ml1: 8188 ComfyUI, 8190 CosyVoice, 8191 Qwen3-TTS,
+# 8192 IndexTTS-2, 8193 Kokoro, 8194 VibeVoice, 8196 Chatterbox,
+# 8765 Parakeet. 8197 picked here.
+CBF_PORT=8197
+
+# Bind address. 0.0.0.0 exposes on all interfaces (incl. the WG tunnel
+# interface 10.100.79.3); 127.0.0.1 restricts to local-only.
+CBF_BIND=0.0.0.0
+
+# ── runtime / GPU ────────────────────────────────────────────────────
+# Device visible inside the container.
+#   1 = RTX A6000 (~12 GB free; the safe default).
+#   0 = RTX 3090  — TIGHT: turbo loads FP32 (not fp16), and the 3090 idles
+#       ~20.5 GB used (shared dev stack), leaving ~3.8 GB free. Measure the
+#       actual footprint before pinning here; it likely will NOT fit in fp32.
+CBF_GPU_DEVICES=1
+
+# Default reference voice (a *.wav stem in CBF_REFERENCE_DIR, or an absolute
+# path). The server prepares this at startup so first request is warm.
+CBF_DEFAULT_VOICE=glados_25s
+
+# Perf levers (Ampere-safe, free). Off with 0. Measured: they don't move TTFA
+# (AR-decode-bound) but don't hurt; bf16 is deferred (fp32 model, no clean cast).
+CBF_TF32=1
+CBF_SDPA_FLASH=1
+
+# ── persistent storage on the host ───────────────────────────────────
+# Reference / predefined voice wavs (mounted at /refs). Shared with the
+# `chatterbox` stack. `_`-prefixed files (bench/A-B scratch) are ignored.
+CBF_REFERENCE_DIR=/worktank/chatterbox/reference_audio
+
+# HuggingFace cache — Chatterbox-Turbo weights. Reused from the `chatterbox`
+# stack (already populated, ~3.8 GB); no re-download. Excluded from restic.
+CBF_CACHE_DIR=/worktank/chatterbox/cache
diff --git a/stacks/chatterbox-fast/Dockerfile b/stacks/chatterbox-fast/Dockerfile
new file mode 100644
index 0000000..34b7804
--- /dev/null
+++ b/stacks/chatterbox-fast/Dockerfile
@@ -0,0 +1,19 @@
+# chatterbox-fast — streaming TTS server.
+#
+# Layers our streaming server (app.py + scheduler.py) on top of the proven
+# chatterbox base image (devnen's, already built locally by the sibling
+# `chatterbox` stack). That base carries the chatterbox lib + torch +
+# fastapi/uvicorn/pydantic — verified present — so this stays a thin overlay.
+#
+# Build on irv-ml1, where local/chatterbox:<tag> exists. Bump the base via the
+# CHATTERBOX_BASE build arg (compose passes it from .env: CBF_BASE_TAG).
+ARG CHATTERBOX_BASE=local/chatterbox:v1
+FROM ${CHATTERBOX_BASE}
+
+# Only the two runtime modules — tests/bench/README stay out of the image.
+COPY scheduler.py app.py /cbf/
+WORKDIR /cbf
+
+# The base image sets devnen's own entrypoint; clear it and run our server.
+ENTRYPOINT []
+CMD ["python", "app.py"]
diff --git a/stacks/chatterbox-fast/README.md b/stacks/chatterbox-fast/README.md
index 7c13fb4..d441b41 100644
--- a/stacks/chatterbox-fast/README.md
+++ b/stacks/chatterbox-fast/README.md
@@ -39,8 +39,21 @@ regardless of chunking. That is why this is the chatterbox-specific answer.
 | `test_scheduler.py` | GPU-free simulation: asserts no-starvation + ratchet. `python test_scheduler.py` or `pytest`. |
 | `app.py` | FastAPI server: model holder + `POST /tts` (StreamingResponse) + `GET /health`. |
 | `bench.py` | Client: ground-truth TTFB + real 1×-consumer starvation check; saves `.wav` for A/B. |
+| `Dockerfile` | Thin overlay: `FROM local/chatterbox:v1` + our two modules. |
+| `compose.yaml` · `.env.example` | Deploy on irv-ml1 alongside the live `chatterbox`. |
 
-Phase 3 will add `compose.yaml`, `Dockerfile`, `.env.example`.
+## Deploy (Phase 3)
+
+```bash
+scripts/deploy-stack.sh irv-ml1 chatterbox-fast      # push compose+code to the host
+# then on irv-ml1, in /opt/docker/compose/chatterbox-fast/ (after copying .env):
+docker compose build && docker compose up -d
+```
+
+`Dockerfile` is `FROM local/chatterbox:v1` (the sibling stack's image — must exist
+on irv-ml1) + `COPY scheduler.py app.py`. GPU pin and voices/cache paths come from
+`.env` (see `.env.example`). Default GPU is **device 1 (A6000)** — turbo loads fp32,
+so the 3090's tight free VRAM likely won't fit; measure before pinning device 0.
 
 ## API
 
diff --git a/stacks/chatterbox-fast/compose.yaml b/stacks/chatterbox-fast/compose.yaml
new file mode 100644
index 0000000..882d547
--- /dev/null
+++ b/stacks/chatterbox-fast/compose.yaml
@@ -0,0 +1,55 @@
+# chatterbox-fast — custom streaming TTS server (sub-second time-to-first-audio
+# via adaptive buffer-ratchet chunking on Chatterbox-Turbo). Deployed ALONGSIDE
+# the live `chatterbox` (:8196) on irv-ml1 — burn in, then flip the catalog.
+#
+# Convention note: mirrors the sibling `chatterbox` stack on this host — GPU via
+# `runtime: nvidia` + NVIDIA_VISIBLE_DEVICES (not the repo's generic device_ids),
+# and accessed by host IP:port (no traefik-net; these GPU TTS services aren't
+# traefik-fronted). Kept consistent with the proven sibling over the generic rule.
+#
+# All tunables live in .env — edit that, not this file.
+
+services:
+  chatterbox-fast:
+    image: local/chatterbox-fast:${CBF_TAG:-v1}
+    build:
+      context: .
+      dockerfile: Dockerfile
+      args:
+        CHATTERBOX_BASE: local/chatterbox:${CBF_BASE_TAG:-v1}
+    container_name: chatterbox-fast
+    restart: unless-stopped
+    runtime: nvidia
+    ports:
+      - "${CBF_BIND:-0.0.0.0}:${CBF_PORT:-8197}:8197"
+    environment:
+      # GPU pin. Default device 1 (A6000) — turbo loads fp32 (~not the fp16 old
+      # notes assumed), so the 3090's tight free VRAM may not fit; see .env.example.
+      - NVIDIA_VISIBLE_DEVICES=${CBF_GPU_DEVICES:-1}
+      - HF_HOME=/app/hf_cache
+      - CBF_MODEL_DEVICE=cuda
+      - CBF_VOICES_DIR=/refs
+      - CBF_DEFAULT_VOICE=${CBF_DEFAULT_VOICE:-glados_25s}
+      - CBF_BIND=0.0.0.0
+      - CBF_PORT=8197
+      - CBF_TF32=${CBF_TF32:-1}
+      - CBF_SDPA_FLASH=${CBF_SDPA_FLASH:-1}
+    volumes:
+      - ${CBF_REFERENCE_DIR:-/worktank/chatterbox/reference_audio}:/refs
+      - ${CBF_CACHE_DIR:-/worktank/chatterbox/cache}:/app/hf_cache
+    healthcheck:
+      # Our app exposes /health → {"status":"ok",...} once the model is loaded.
+      # python urllib (devnen base ships no curl); strip spaces so the match is
+      # formatting-agnostic. 127.0.0.1 explicitly (uvicorn binds IPv4 only).
+      test: ["CMD-SHELL", "python3 -c \"import urllib.request,sys; b=urllib.request.urlopen('http://127.0.0.1:8197/health',timeout=5).read(); sys.exit(0 if b'\\\"status\\\":\\\"ok\\\"' in b.replace(b' ',b'') else 1)\""]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      # Weights are HF-cached already (~16s load measured); generous anyway.
+      start_period: 120s
+    labels:
+      - homepage.group=AI Systems
+      - homepage.name=Chatterbox Fast
+      - homepage.icon=mdi-account-music-outline
+      - homepage.description=Streaming TTS — sub-second first-audio, adaptive-chunk (irv-ml1)
+      - homepage.href=http://10.100.79.3:${CBF_PORT:-8197}