The host kept its own copy of the version-naming rule, byte-identical to
the one in contract/migration: slice the leading 13 characters, no check.
Two copies of a convention that applications also have to follow is two
things to keep in step, and the copies had already stopped matching - core
now rejects a name that carries no timestamp, and this one still accepted
"add_orders.go" and registered a migration under that string as its
version, which nothing would ever match and nothing would report.
Delegate instead, so there is one implementation of the rule and an app's
migration and a host migration derive their version the same way.
The test pins the reject case, not just the happy path: a re-divergence
that only sliced would still pass the happy path.
Claude-Session: https://claude.ai/code/session_01HPTAw8b8tAdFNFn8rKdPYx
core's sdk/contract/migration keeps its own process-wide registry, because
that is the only door open to an application that must not import the host.
Nothing here ever opened it: ForApp("crm").SetVersion(...) compiled,
registered, and then never ran - no error, no mention in status, nothing.
mergedEntries unions the host's own registry with contract/migration's
Snapshot(), and status, run and AppCodes all read through it, so migrate,
status, --dry-run and --app see an application's migrations exactly as they
see the host's. Version namespacing already keeps the two apart, so a key
collision should not be reachable; the host's own registration wins if one
ever is, rather than being silently replaced.
Claude-Session: https://claude.ai/code/session_01HPTAw8b8tAdFNFn8rKdPYx
An applied migration printed its count - a bare '1' - so a database with
seven of them wrote seven lines of '1' at every start, and a failure said
only which error, never which migration.
It now names each one as it applies, reports the total, and says so when
there is nothing to do.
zhangwenjian