Phase 3 built the seam; nothing stopped it being undone one convenient import at
a time. Two rules, both proven able to fail.
TestDatabaseSQLImportersAreDeclared freezes the blast radius of database/sql.
Twenty packages import it today and that set is now explicit. A new package that
needs its own SQL must be added deliberately, with a reason. The rule also fails
in the other direction — if a listed package stops importing database/sql, the
list must shrink, so it cannot rot into a meaningless allowlist.
TestThreadedConsumersStayOffSQL is the concrete regression guard: internal/
playback was moved onto catalog.Store, and this fails if it reaches for *sql.DB
again.
Both checks read non-test files only, so a package that needs database/sql
purely to build a test database is not forced onto the list.
Proven by breaking each on purpose:
- dropping internal/media from the list -> "imports database/sql but is not
in sqlImporters"
- adding internal/natsort (no SQL) -> "is listed ... but no longer
imports database/sql"
- re-adding database/sql to playback -> "undoes the seam"
All restored afterwards and the files verified unchanged.
Seven arch rules now, each able to fail. gofmt clean, build 0, vet 0, 25
packages pass.
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