---
name: halogen-npu-lane-boot-loop-triage
description: "Triage a frank-dragoon (halogen-flash-server) unit crash-loop caused by the NPU lane: signature classification, restart-debris trap, XRT mount-path census, and the transient env-file proof boot."
---

Triage when `frank-dragoon` (or any halogen-flash-server unit with `HALOGEN_NPU_MODELS` armed) sits in `activating (auto-restart)` with `ExecStart … code=exited, status=1/FAILURE` seconds after start, while `/health` stays dark.

## 1. Classify the exit BEFORE touching the config
- `NRestarts` climbing + exit in <5 s = refusal, not an engine fault. Read `journalctl -u frank-dragoon --since "-30m"` AND the engine log `/home/dank/logs/frank_dragoon.log` (engine stdout never goes to the journal).
- Lane signature: log ends with `halogen npu: … <name>: N files checked against this image's record` then `halogen-npu: No such library '<path>'` + `the NPU engine exited before it was ready (rc=1)` → **the NPU lane exit is fatal to the whole container** (supervisor kills the Flash engine with it). Chat-down is the lane's fault even though chat code never changed.
- KV/pre-flight lines present but no `locked in RAM` line = died before weight pinning.

## 2. The restart-debris trap
`Restart=always` re-runs the failing boot every ~10 s; each attempt leaves GPU/NPU handles being released, and the next boot logs `GTT in use before this start: N GiB … held by 1 process(es)`. That NOTE is debris from your own crash-loop — do not chase it as a foreign co-tenant (real co-tenants: ComfyUI `python` on `/dev/kfd`, find with `sudo fuser -v /dev/dri/renderD128 /dev/kfd`). `sudo systemctl stop <unit>` FIRST, then any diagnosis.

## 3. XRT path census (the `No such library '/opt/xilinx/lib/<multiarch>/libxrt_*.so.2'` case)
- The image ships NO XRT at all (`find / -xdev -name "libxrt*"` inside the image = empty); the NPU child `dlopen`s the host's libs through the serve script's mounts, which land at TWO destinations only: `/opt/xilinx/xrt/lib/<L>` and `$XRT_DIR/<L>`. A child searching `/opt/xilinx/lib/<multiarch>/` names a THIRD prefix nobody mounts.
- The serve loop resolves `REAL="$(readlink -f …)"` and mounts resolved files — if a host package upgrade retargets the symlinks (check `grep libxrt /var/log/dpkg.log` + `ldconfig -p | grep xrt` mtimes vs the last good boot), the file set the child expects can change under byte-identical mounts.
- Rootless gotcha: `podman mount` fails outside `podman unshare` and leaves `$M` EMPTY — `grep -r pat "$M/opt"` then greps your CWD = HOST tree (false hits like `/opt/fastflowlm`). Always `podman unshare bash -c 'M=$(podman mount $C); …'` or `--entrypoint ls|cat` probes instead, and distrust hits that name host-only paths.

## 4. Proof boot without touching production
The serve script honors `FRANK_DRAGOON_ENV_FILE` (sanctioned seam). Throwaway script on the host:
1. scratch env: `source /home/dank/serverAppConfigs/scripts/frank-dragoon.env` + the knob under test.
2. `sed` the serve script to inject the candidate extra mounts into the `NPU_ARGS+=(--device …` line — mount RESOLVED real files (`.so.2.25.00`), never symlinks (vendor: dangling links inside the container).
3. `export FRANK_DRAGOON_ENV_FILE=/tmp/… FRANK_DRAGOON_LOG=/tmp/…; FRANK_DRAGOON_CONTAINER=<scratch-name> timeout 1200 /tmp/serve-test.sh` — the container still publishes 7770, so `systemctl stop` the unit first (port binds at CREATE, exit 126 on race).
4. Retire same session: `podman rm -f <scratch-name>`, trash `/tmp` scripts; the unit stays stopped until the real fix deploys.

## 5. Restore chat while the lane is unfixed
`HALOGEN_NPU_MODELS=` (blank) is the documented one-line lane-off switch — lane absent = endpoint exactly as before the lane existed. Land through git + `deploy.sh dankclaw --service frank-dragoon`; never hand-edit the remote env.