The unified regeneration engine, version stamping, and staleness detection that let the whole live fleet be improved without taking anything down.
Because a Doozer site is generated from data, every site can be regenerated by today's pipeline. With 2,400+ live sites, the challenge is doing that safely, at scale, without ever going dark. The Foundation Sprint built the machinery.
Every generated artifact is version-stamped, so the system can detect which sites were built by an older pipeline and are now stale. This is what makes a fleet-wide upgrade knowable instead of guesswork: "which sites still need the new section framework / family fix?"
includes/regeneration.php — regenerationRun($bizId, $mode). Modes: recolor, redesign, reroll, content, full, fix_readability. Each is cost-aware (content-only regen is ~$0.02 and keeps the design) and quality-gated with rollback — a regeneration that fails the quality check is reverted, so a bad AI run can never degrade a live site. This retires the old "magical regen" in favor of à la carte control (checkboxes: photos / vision / recolor / new-muse / content / full).
Key fact: content regen never touches the muse. The muse is resolved via a shared cascade (museResolve), not stored per-business, so regenerating content leaves the design identity intact.
The Foundation endgame is one System Health / Upgrade cockpit: see fleet version distribution, detect stale, and run the fleet upgrade runner that calls the unified engine at scale (e.g. converting the elks.club sites in one pass). Supported by the Schema Audit tool (master-schema-vs-live drift) so a feature never silently no-ops in prod because a column drifted.
This is the maintenance backbone that lets the flywheel keep turning: the fleet gets better as the pipeline does, on purpose, without downtime.