How it works
A migration is a loop over pages. Understanding the loop explains almost everything people find surprising, including why the pages-checked number dwarfs the pages-changed number.
It also explains the safety model: every changed page becomes a new version, and nothing is ever deleted.
#In this section
The migration lifecycleWhat actually happens between pressing Start migration and reading the results.How pages are foundSearch decides the scope, which explains the counts, the ordering, and the pages that quietly drop out.How a page is rewrittenEvery changed page becomes a new version labelled "Migrated by Capable", and unchanged pages are left completely alone.What is never touchedThe guarantees worth knowing before you run anything: what is created, what is read, and what is never deleted.Permissions and the admin keyWho can run a migration, which pages it can reach, and what the admin key actually changes.How long a migration takesWhat drives the clock, what the estimate is based on, and why the tab has to stay open.
#Related
A loop over pages. Everything else is tidying.
