Live read-only checks found four duplicate imports: swsh9.5tg, swsh10.5tg, swsh11.5tg and swsh12.5tg. Each has the same 30 TG numbers and French names already available in its parent expansion through the existing *tg aliases.

The API omits these duplicate set entries and resolves their legacy set URLs to the parent. Duplicate imports are not additive companion subsets: they must not append a second copy of the cards or inflate the total (245 remains 245 for Silver Tempest). The four expansions are Brilliant Stars, Astral Radiance, Lost Origin and Silver Tempest.

Six new regression tests failed before the fix; all 1044 API tests pass after it, including TypeScript compilation. Coverage includes all four aliases, localized set lists, paginated URLs, collector identity, counts and read-only queries.

This removes catalogue duplicates, not stored card records. Holdings, direct card lookup and price history remain intact; physical duplicate-card identity reconciliation would require a separate reviewed migration. No migration, production deployment or mobile build was performed. Deploy the backend through the approved process before expecting the installed app to reflect the change.