The host runner's Docker CLI forces the buildx path when DOCKER_BUILDKIT=1
is set, but buildx isn't installed on the runner, so the build errored
before starting. Revert the env var and remove the two RUN --mount=type=cache
directives so the legacy builder can parse the Dockerfile. Normal layer
caching still applies; only the npm download cache reuse is lost.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The host runner's docker build was falling back to the legacy builder,
which can't parse the BuildKit-only RUN --mount=type=cache syntax in the
Dockerfile. Set DOCKER_BUILDKIT=1 to route the build through the daemon's
integrated BuildKit engine.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
jason
Jason Stedwell