diff --git a/infra/deploy/forgejo/README.md b/infra/deploy/forgejo/README.md
index caf2ffe..8ad737d 100644
--- a/infra/deploy/forgejo/README.md
+++ b/infra/deploy/forgejo/README.md
@@ -109,36 +109,40 @@ labels where there used to be two separate runners.
 
 ## Custom CI job image (`ci-runner/`)
 
-`ci-runner/Dockerfile` replaces the stock `node:20-bookworm` image most
-`docker`-labeled workflow jobs run in. That base is leftover from when the
-frontend was Python/Jinja and the old GitHub runner also built JS assets for
-it — the frontend is Go now, nothing in `.forgejo/workflows/` uses npm/node.
-Every `docker`-labeled build-push job also currently re-installs the Docker
-CLI on each run (`apt-get install docker.io`), which pulls in the classic
-builder rather than BuildKit (the classic builder mishandles `COPY
---chown=<name>` group resolution — a real bug hit during the frontend Go
-rewrite). `ci-runner` is a slim Debian base with `docker-ce-cli` +
-`docker-buildx-plugin` (BuildKit) preinstalled, plus `git`/`python3`/
-`python3-yaml` for the other jobs that need them (`shell-lint`,
-`observability-validate`).
+`ci-runner/Dockerfile` still bases on `node:20-bookworm` — Node is a hard
+requirement, not leftover: Forgejo's runner executes `actions/checkout@v4`
+(used by every workflow) as `node dist/index.js` *inside the job container*,
+regardless of whether the workflow itself uses npm/node. (v1 of this image
+tried a Node-free Debian-slim base and broke every job's checkout step —
+`node: executable file not found` — within a minute of going live; reverted
+immediately.) What it actually fixes: every `docker`-labeled build-push job
+currently re-installs the Docker CLI on each run (`apt-get install
+docker.io`), which pulls in the classic builder rather than BuildKit (the
+classic builder mishandles `COPY --chown=<name>` group resolution — a real
+bug hit during the frontend Go rewrite). `ci-runner` adds `docker-ce-cli` +
+`docker-buildx-plugin` (BuildKit) on top of the same Node base, plus
+`git`/`python3`/`python3-yaml` for the other jobs that need them
+(`shell-lint`, `observability-validate`).
 
-Pushed as `git.thermograph.org/emi/thermograph/ci-runner:v1`. Rebuild/push
-(requires a PAT with `write:package` scope — the embedded git-remote token
-lacks it, same requirement documented in `backend-build-push.yml`):
+Current tag: `git.thermograph.org/emi/thermograph/ci-runner:v2` (`v1` is
+broken — do not register any runner against it). Rebuild/push (requires a PAT
+with `write:package` scope — the embedded git-remote token lacks it, same
+requirement documented in `backend-build-push.yml`):
 
 ```bash
-docker build -t git.thermograph.org/emi/thermograph/ci-runner:v1 deploy/forgejo/ci-runner
-docker push git.thermograph.org/emi/thermograph/ci-runner:v1
+docker build -t git.thermograph.org/emi/thermograph/ci-runner:vN deploy/forgejo/ci-runner
+docker push git.thermograph.org/emi/thermograph/ci-runner:vN
 ```
 
-`register-lan-runner.sh`'s `LABELS` default now points at this image, so
+`register-lan-runner.sh`'s `LABELS` default points at the current tag, so
 fresh registrations pick it up automatically. The live runner is cut over by
 editing the `labels` array in `~/forgejo-runner/.runner` on the desktop (same
-runner id/token, no re-registration needed) and restarting the service. Only
-after a real job has run successfully under the new image should the
+runner id/token, no re-registration needed) and restarting the service —
+**verify a real job runs green under the new image before relying on it**,
+same way v1's break was caught. Only after that verification should the
 now-redundant `apt-get install docker.io` / `python3-yaml` steps be removed
-from the workflows that had them — removing them first would break
-every job still running on `node:20-bookworm`.
+from the workflows that had them — removing them first would break every job
+still running on the stock `node:20-bookworm` image.
 
 ## Why Postgres here and not the Thermograph app's TimescaleDB
 
diff --git a/infra/deploy/forgejo/ci-runner/Dockerfile b/infra/deploy/forgejo/ci-runner/Dockerfile
index 4db36b6..e4259e0 100644
--- a/infra/deploy/forgejo/ci-runner/Dockerfile
+++ b/infra/deploy/forgejo/ci-runner/Dockerfile
@@ -2,17 +2,21 @@
 # jobs (see ../register-lan-runner.sh) — used by every backend/frontend
 # build-push, deploy, and validation workflow that needs `docker build`.
 #
-# Replaces the stock node:20-bookworm image. That base is pure leftover from
-# when the frontend was a Python/Jinja app the old GitHub runner also built
-# JS assets for; the frontend is Go now (no npm/node anywhere in
-# .forgejo/workflows/) so carrying a full Node runtime here just adds weight.
-# Every workflow using the `docker` label also currently re-provisions the
-# Docker CLI itself on each run via `apt-get install docker.io` — that step
-# costs ~15-20s per job and, more importantly, installs the CLASSIC Docker
-# builder rather than BuildKit, which mishandles `COPY --chown=<name>` group
-# resolution on images without a matching system group (a real bug hit during
-# the frontend Go rewrite). Installing docker-buildx-plugin here makes
-# BuildKit the default, closing that bug class, on a much smaller base.
+# Base stays node:20-bookworm, NOT a Node-free slim image (v1 of this file
+# tried that and broke every job: `actions/checkout@v4` is a JS action that
+# Forgejo's runner execs as `node dist/index.js` *inside the job container*,
+# so a Node runtime is a hard requirement regardless of whether the workflow
+# itself uses npm/node — this repo's own workflows don't, but the checkout
+# step every one of them starts with does).
+#
+# What this image actually fixes: every workflow using the `docker` label
+# currently re-provisions the Docker CLI on each run via `apt-get install
+# docker.io` — that step costs ~15-20s per job and, more importantly,
+# installs the CLASSIC Docker builder rather than BuildKit, which mishandles
+# `COPY --chown=<name>` group resolution on images without a matching system
+# group (a real bug hit during the frontend Go rewrite). Installing
+# docker-buildx-plugin here makes BuildKit the default, closing that bug
+# class, and skips the per-job install entirely.
 #
 # Build/push (manual — see ../README.md for when to rebuild):
 #   docker build -t git.thermograph.org/emi/thermograph/ci-runner:vN \
@@ -23,7 +27,7 @@
 # in ~/forgejo-runner/.runner on the runner host directly (same runner
 # id/token, no re-registration needed) and updating register-lan-runner.sh's
 # LABELS default so future re-provisioning picks it up too.
-FROM debian:bookworm-slim
+FROM node:20-bookworm
 
 RUN apt-get update -qq \
     && apt-get install -y -qq --no-install-recommends \
@@ -38,4 +42,5 @@ RUN apt-get update -qq \
     && rm -rf /var/lib/apt/lists/* /etc/apt/sources.list.d/docker.list
 
 RUN docker --version && docker buildx version && git --version \
+    && node --version \
     && python3 -c "import yaml; print('PyYAML', yaml.__version__)"
diff --git a/infra/deploy/forgejo/register-lan-runner.sh b/infra/deploy/forgejo/register-lan-runner.sh
index 6edb92b..c35660d 100755
--- a/infra/deploy/forgejo/register-lan-runner.sh
+++ b/infra/deploy/forgejo/register-lan-runner.sh
@@ -26,7 +26,7 @@ set -euo pipefail
 FORGEJO_URL="${1:?usage: $0 <forgejo_url> <registration_token>}"
 TOKEN="${2:?}"
 RUNNER_DIR="${RUNNER_DIR:-$HOME/forgejo-runner}"
-LABELS="${LABELS:-docker:docker://git.thermograph.org/emi/thermograph/ci-runner:v1,thermograph-lan}"
+LABELS="${LABELS:-docker:docker://git.thermograph.org/emi/thermograph/ci-runner:v2,thermograph-lan}"
 
 echo "==> Stopping and disabling the old GitHub Actions runner service, if present"
 systemctl --user stop github-actions-runner 2>/dev/null || true