BACKLOG — phase `samever`

Build backlog

M1 — resolver reads head version; step-back chain; unit tests. (CLAIMED 2026-06-17)
- abra.head_compose_version(recipe) — parse coop-cloud.<stack>.version from head compose.yml
- warm_reconcile.version_key + newest_older_version — single coop-cloud ordering source
- resolver chain: override → (canonical if ≠ head) → (newest-older if canonical==head) → main-tip → skip
- unit tests extended (13 pass): step-back, canonical≠head unchanged, no-older→skip, ordering, None-head
M2 — prove in real CI: nightly steady-state (canonical==latest) cold-on-latest steps back (base_version < latest); PR form (non-version-bump PR, head==canonical); discourse #4 version-bump UNAFFECTED; spot-check ≥1 other enrolled recipe. Awaiting M1 PASS before starting real-CI runs.

Run A (custom-html cold-on-latest, /root/samever-runA.log on cc-ci): launched 04:3xZ. No canonical yet → upgrade base kind=skip (head==main tip); on green promotes canonical→latest 1.13.0+1.31.1.
Run B (next): cold-on-latest again → canonical==head → expect step-back base 1.11.0+1.29.0 (<latest).