diff --git a/migrations/20260906000002_drop_legacy_share_tables.sql b/migrations/20260906000002_drop_legacy_share_tables.sql
new file mode 100644
index 00000000..4cf8b9ca
--- /dev/null
+++ b/migrations/20260906000002_drop_legacy_share_tables.sql
@@ -0,0 +1,38 @@
+-- Drop the pre-Round-3 per-domain share tables. Every reader/writer
+-- was retired in the Rust cleanup landing alongside this migration:
+--
+--   * `CalendarUseCase::{list_shared_calendars, share_calendar,
+--     remove_calendar_sharing, get_calendar_shares}` — gone
+--   * `AddressBookUseCase::{share_address_book, unshare_address_book,
+--     get_address_book_shares}` — gone
+--   * `CalendarRepository` / `AddressBookRepository` share methods — gone
+--   * SQL bodies in `calendar_pg_repository.rs` /
+--     `address_book_pg_repository.rs` that touched these tables — gone
+--
+-- Data lives on in `storage.role_grants` (backfilled by
+-- `20260906000001_backfill_calendar_address_book_role_grants.sql`).
+-- The one-release rollback window between the backfill and this drop
+-- was left implicit — no external process reads either table today.
+
+DROP TABLE IF EXISTS caldav.calendar_shares;
+DROP TABLE IF EXISTS carddav.address_book_shares;
+
+-- Post-flight introspection: refuse to complete if either table is
+-- still present. Guards against a name-collision resurrection by an
+-- older seed file or hand-rolled restore step.
+DO $$
+DECLARE
+    stray_count INT;
+BEGIN
+    SELECT COUNT(*) INTO stray_count
+    FROM pg_class c
+    JOIN pg_namespace n ON n.oid = c.relnamespace
+    WHERE (n.nspname = 'caldav'  AND c.relname = 'calendar_shares')
+       OR (n.nspname = 'carddav' AND c.relname = 'address_book_shares');
+
+    IF stray_count > 0 THEN
+        RAISE EXCEPTION
+            'Migration 20260906000002 finished with % legacy share table(s) still present',
+            stray_count;
+    END IF;
+END $$;
diff --git a/src/domain/repositories/address_book_repository.rs b/src/domain/repositories/address_book_repository.rs
index f9841c11..6e86c9cb 100644
--- a/src/domain/repositories/address_book_repository.rs
+++ b/src/domain/repositories/address_book_repository.rs
@@ -12,9 +12,8 @@ pub type AddressBookRepositoryResult<T> = Result<T, DomainError>;
 /// The pre-Round-3 methods that read/wrote `carddav.address_book_shares`
 /// (`get_shared_address_books`, `share_address_book`,
 /// `unshare_address_book`, `get_address_book_shares`) have been removed
-/// from this trait. The `carddav.address_book_shares` table still
-/// exists for one-release rollback safety; a follow-up migration drops
-/// it.
+/// from this trait, and the backing table was dropped in
+/// `20260906000002_drop_legacy_share_tables.sql`.
 pub trait AddressBookRepository: Send + Sync + 'static {
     async fn create_address_book(
         &self,
diff --git a/src/domain/repositories/calendar_repository.rs b/src/domain/repositories/calendar_repository.rs
index 1216353e..8719fbdb 100644
--- a/src/domain/repositories/calendar_repository.rs
+++ b/src/domain/repositories/calendar_repository.rs
@@ -10,9 +10,8 @@ pub type CalendarRepositoryResult<T> = Result<T, DomainError>;
 /// the pre-Round-3 methods that read/wrote `caldav.calendar_shares`
 /// (`list_calendars_shared_with_user`, `user_has_calendar_access`,
 /// `share_calendar`, `remove_calendar_sharing`, `get_calendar_shares`)
-/// have been removed from this trait. The `caldav.calendar_shares` table
-/// still exists for one-release rollback safety; a follow-up migration
-/// drops it.
+/// have been removed from this trait, and the backing table was dropped
+/// in `20260906000002_drop_legacy_share_tables.sql`.
 pub trait CalendarRepository: Send + Sync + 'static {
     /// Creates a new calendar
     async fn create_calendar(&self, calendar: Calendar) -> CalendarRepositoryResult<Calendar>;