- test_host_updater: stub git/docker now model cat-file/show/rev-parse --verify and compose config/image inspect. The two update-path tests were failing on Linux CI (skipped locally on macOS, no flock). Adds tests for pull-before-checkout + .env pins, a missing pinned image leaving the node unchanged, and a pre-pinning target still updating. - drb-update.sh: load image-tags.sh via a variable + eval and confirm the functions exist; `source <(git show ...)` "succeeded" with nothing defined when git show failed, wedging every later update. - install.sh: skip pinning (warn) when the checked-out ref predates scripts/image-tags.sh instead of dying on the missing file. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>