# blender

**Blender 5.2.2 LTS on fv-ml1 GPU 3, on demand.** Agents drive it; there is also a browser
desktop to watch it or take over. Prime, 2026-09-27: "go ahead with gpu 3, both". He does not
use Blender himself, so the agent side (MCP) is the primary interface.

| | |
|---|---|
| **Desktop** | `https://10.251.50.54:3001` (self-signed cert). Basic auth: user `blender`, password `secret get fv-ml1/blender-web-password`. |
| **Image** | `lscr.io/linuxserver/blender:5.2.2-ls241@sha256:9216c77a…` (Selkies 2.0 Wayland desktop, NVENC stream). |
| **GPU** | GPU 3 only (`NVIDIA_VISIBLE_DEVICES=3`). About 270 MiB is held while the desktop runs. |
| **Files** | `/work` → `/tank/blender` (projects, assets, renders; **not backed up**). `/config` → `/opt/docker/data/blender` (prefs, add-ons; restic). Files are owned by infra-ops (uid 1002), so agents can `scp` in and out. |

## ⚠ On demand: GPU 3 is borrowed

GPU 3 is the fleet's reserve card for a full-size vLLM seat (`servers/fv-ml1/README.md`).
Blender uses it only while in use:

```bash
ssh infra-ops@10.251.50.54 'cd /opt/docker/compose/blender && docker compose up -d'   # start
ssh infra-ops@10.251.50.54 'cd /opt/docker/compose/blender && docker compose down'    # stop, card back to 0
```

`restart: "no"`, so a reboot never brings it back. **When a big seat moves onto GPU 3, Blender
stays down.**

## Headless rendering (no desktop needed)

```bash
ssh infra-ops@10.251.50.54 'docker exec -u abc blender blender -b /work/<file>.blend -E CYCLES -o /work/out/frame_#### -a -- --cycles-device OPTIX'
```

Run as `-u abc`, the image's user, mapped to uid 1002, so outputs land owned by infra-ops.

## Acceptance (2026-09-27, 1356)

- Cycles sees the card on both OptiX and CUDA: "NVIDIA RTX PRO 6000 Blackwell Max-Q Workstation
  Edition". The build ships `kernel_sm_120.cubin` plus OptiX PTX.
- Self-test (`/tank/blender/render_test.py`): a subdivided glass monkey, 1920×1080, 1024 samples,
  32 bounces, no denoise. **OptiX 3.54 s against CPU 22.71 s (96 threads).** That is n=1 per
  device: a functional check that the GPU is really used, not a benchmark. A trivial default-cube
  scene could not separate them (0.59 s against 0.65 s), which is why the self-test scene is heavy.
- Web auth: no credentials gives 401, a wrong password 401, the right one 200.
- Selkies: "Render node 1 encodes H264, AV1, H265 on nvenc"; the Wayland renderer runs GL on GPU 3.

## Agent control (MCP)

Being researched with dvalin-smithy-dev: which Blender MCP server, and how it reaches Blender
across hosts. This section fills in once the choice is made. ⚠ Most Blender MCP add-ons expose
"run arbitrary Python inside Blender" on a TCP port. Treat that port like a shell: bind it to
the container or the LAN only, never publish it wider.