The armed boot reached the engine and died in its own preflight:
halogen npu: /dev/accel/accel0 is here, but this process cannot open it
(crw-rw---- nobody:nogroup).
The node is root:render 0660 and a rootless container maps exactly one uid/gid,
so `render` is unmapped inside it and `--group-add keep-groups` — the vendor's
advice, and the ComfyUI pattern for /dev/kfd — cannot grant a group the
namespace does not map. Measured 2026-10-19 from a `dank` shell already in
`render`: without the flag denied, with the flag denied, with the udev mode
0666 the open succeeds (OPEN_OK). Same wall 99-comfyui-gpu-access.rules already
solved for the GPU compute nodes, so the accel node gets its counterpart:
dankclaw/udev/98-halogen-npu-access.rules — KERNEL=="accel[0-9]*",
SUBSYSTEM=="accel", MODE="0666"
The deployer installs the rule, reloads rules, re-triggers the node and only
then checks the mode; the serve script refuses any node that is not
other-writable, naming the rule, so this cannot return as a crash loop (189
restarts while chat was down is the failure mode being closed).
Both checks read the permission bit directly: `[ -o FILE ]` is not
"other-writable" — it means "exists" and `-o` doubles as the OR operator inside
test, which is why the first cut of the gate refused everything.
Dragoon seam: 33 -> 35 tests. The fixture node is 0666 like the installed one,
a 0660 node is refused with the rule named and nothing rendered, and the rule
file's shape plus the deployer's install/trigger are asserted.
The first revision guarded the kfd line with SUBSYSTEM=="misc", which never
matches (misc-class devices carry no subsystem for udev matching), so the rule
was read but never fired and /dev/kfd stayed 0660 root:render. Name-only match
applies 0666 on creation and on trigger.
Also fixes test-changed.sh to exit 0 when changed paths map to zero tests
(udev rules are mapped-but-untestable) instead of invoking bats with an empty
selection.
The comfyui container is spawned by a systemd user unit whose spawn context
carries no supplementary groups, so render-group access to /dev/kfd and
renderD128 was structurally unreachable (keep-groups preserved an empty set;
named group_add 'render' fails name lookup inside the userns). World-mode on
the compute nodes is the only spawn-context-independent grant; display cards
keep their modes. Apply: install to /etc/udev/rules.d, udevadm control
--reload-rules, then trigger by subsystem to re-apply modes to live nodes.
Also maps dankclaw/udev/* in the focused-test selector (not bats-testable).
Frank