One base (Temurin 21 JDK, node/npm/tsc, php/composer, maven, sqlite, bwrap)
built only when its Dockerfile or dependencies change, plus a browser variant;
engine/search/VM images FROM base@sha256 with the code in the last layer; the
image workflow runs on dispatch, tags, Dockerfile or pin changes, with a build
cache. Executor NPROC bound relative to the current process count.
Co-Authored-By: Claude Fable 5.1 <[email protected]>
