main
u
1
u
2
u
3
s̄
main
= 6.8 (σ = 1.2)
staging
u
4
u
5
s̄
staging
= 7.4 (σ = 1.1)
▼
s̄
staging
> s̄
main
?
(Welch's
t
-test, α = 0.05,
n
min
= 20)
yes ▼
no ▼
PROMOTE
staging → new main
FREEZE
retain for audit, hide from runtime