diff --git a/stacks/comfyui/compose.yaml b/stacks/comfyui/compose.yaml
index d11454b..44a455a 100644
--- a/stacks/comfyui/compose.yaml
+++ b/stacks/comfyui/compose.yaml
@@ -1,8 +1,9 @@
 # ComfyUI — node-based Stable Diffusion / Flux inference UI.
 #
-# Runs on irv-ml1 (dual GPU: RTX 3090 + RTX A6000). Both GPUs are
-# exposed via NVIDIA_VISIBLE_DEVICES=all so GPU selection happens
-# per-workflow inside ComfyUI.
+# Runs on irv-ml1 (dual GPU: RTX 3090 + RTX A6000). PINNED to the A6000
+# (device 1) via NVIDIA_VISIBLE_DEVICES=1 — the 3090 hosts the audio/TTS
+# zoo (chatterbox, parakeet, vibevoice, ytvc, kokoro) so ComfyUI gets the
+# full 48 GB A6000 to itself (operator consolidation 2026-06-18).
 #
 # All user state — models, workflows, custom_nodes, input, output —
 # lives under a single BASE_DIRECTORY tree on /worktank (462 GB
@@ -30,7 +31,11 @@ services:
     ports:
       - "${COMFYUI_BIND:-0.0.0.0}:${COMFYUI_PORT}:8188"
     environment:
-      - NVIDIA_VISIBLE_DEVICES=all
+      - NVIDIA_VISIBLE_DEVICES=1
+      # Pin torch at the current 2.12.1+cu129 so the boot script stops
+      # auto-upgrading it — compiled SageAttention kernels must not drift
+      # (comfy-dev torch-pin, operator-approved 2026-06-18).
+      - DISABLE_UPGRADES=true
       - WANTED_UID=${COMFYUI_UID}
       - WANTED_GID=${COMFYUI_GID}
       - BASE_DIRECTORY=/basedir
diff --git a/stacks/parakeet/compose.yaml b/stacks/parakeet/compose.yaml
index 7a0cb5d..133ddea 100644
--- a/stacks/parakeet/compose.yaml
+++ b/stacks/parakeet/compose.yaml
@@ -29,7 +29,7 @@ services:
     ports:
       - "${PARAKEET_BIND:-0.0.0.0}:${PARAKEET_PORT}:8000"
     environment:
-      - NVIDIA_VISIBLE_DEVICES=all
+      - NVIDIA_VISIBLE_DEVICES=0
       - MODEL_DIR=/models
       - MODEL_URL=${PARAKEET_MODEL_URL}
       - PROVIDER=${PARAKEET_PROVIDER:-cuda}