**Motivations :**
- keep deploy-by-script-to strict when source-of-truth site slugs are unavailable
- align ia_dev deploy wrappers with lecoffreio-only deployment model
- avoid hidden default behavior in secrets layout validation
**Root causes :**
- deploy-by-script-to still had a fallback that reintroduced implicit site assumptions
- helper comments and branch-align wording still referenced removed multisite lines
**Correctifs :**
- remove fallback site injection in deploy-by-script-to and fail explicitly on empty site list
- update change-to-all-branches orchestration comment to source-of-truth semantics
- align deploy-conf-handling nested secrets guidance with lecoffreio-only tree
**Evolutions :**
- strengthen strict mode behavior for deployment prerequisites
**Page affectées :**
- deploy/deploy-by-script-to.sh
- deploy/change-to-all-branches.sh
- deploy/lib/deploy-conf-handling.sh