Blender is now a mandatory stage in draupnir's pipeline (Prime, 2026-09-28), and draupnir asked
for eight add-ons from extensions.blender.org: SurfacePsycho 0.10.4, CAD Sketcher 0.32.1,
3D-Print Toolbox 1.4.1, STEP Importer 1.2.1, Bool Tool 2.1.0, LoopTools 4.7.7, MeasureIt 1.8.4,
3MF Import/Export 2.7.7.
- stacks/blender/extensions.lock pins each by version and archive sha256.
- scripts/blender-extensions sync builds fv-ml1:/tank/blender-extensions/5.2/system with Blender's
own install-file, pre-warms and byte-compiles it, checks a read-only enable, then swaps it in.
It refuses while the GUI or a blender-run job holds the old directory.
- conf/scripts/startup/fleet_extensions.py enables every package in the System repo: in a timer
in the GUI (after the prefs load), and as --python ahead of the caller's args in
blender-run --extensions (a failed enable exits 1 before the caller's script).
- It also patches SurfacePsycho's sp_overwrite_segment_selection from eval() to literal_eval():
the eval walked past MCP safe mode (control: unpatched ran code, patched refuses).
- blender-run: --extensions (bind mounts via --mount so a missing source fails instead of being
created); USER/LOGNAME set, which CAD Sketcher's getpass needs.
- compose.yaml mounts the repo read-only and the hook into the GUI container. NOT yet deployed.
- scripts/blender-probes/extensions_acceptance.py: one operator run per add-on, safe-mode
compliant. Headless 8/9 online and with --network none; CAD Sketcher sketching is GUI-only.
A Python audit hook saw no network/process events (positive control fired).
The MCP server (mcp-for-blender 2.1.1, frozen requirements) runs inside the Blender
container. Its add-on is vendored at upstream 41a18432 (MIT) and started by a
startup hook. scripts/blender-mcp carries the stdio over ssh + docker exec, so the
add-on socket, which runs arbitrary Python with no auth, stays on the container's
localhost with no published port. It also runs there because viewport screenshots
need a filesystem shared by server and Blender. Telemetry is off and safe mode is
on. The hook also defaults Cycles to OptiX on GPU 3, because safe mode forbids
agents from touching preferences.
Verified end to end from nh3-dev: 36 tools; a GPU render of an agent-built scene;
a viewport screenshot; and safe mode refusing 'import os'. Blender left down
(on demand).
Uses linuxserver/blender (Selkies Wayland desktop, NVENC), digest-pinned. The
container sees only GPU 3, has restart "no", and runs only while in use,
because GPU 3 is the reserve card for a full-size vLLM seat. Web desktop on
:3001 with basic auth (vault fv-ml1/blender-web-password). /work is on /tank
and is not backed up; /config lives under /opt/docker (restic).
Acceptance: Cycles finds the card on OptiX and CUDA (sm_120 kernels ship in the
build). The heavy self-test renders in 3.54 s on OptiX vs 22.71 s on CPU, a
functional check with n=1. Web auth answers 401 without credentials and with a
wrong password, and 200 with the right one.
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