first commit

server/prisma/migrations/20260505170000_harden_instance_destroy_idempotency/migration.sql

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+-- Remove historical duplicate destroy markers before adding the guard.
+-- Balance remediation for duplicate refunds must be handled separately because
+-- those rows already affected user balances.
+CREATE TABLE IF NOT EXISTS "user_destroy_records_duplicate_archive" AS
+SELECT a.*, now() AS "archived_at"
+FROM "user_destroy_records" a
+JOIN "user_destroy_records" b
+  ON a."instance_id" = b."instance_id"
+WHERE a."destroyed_at" < b."destroyed_at"
+  OR (a."destroyed_at" = b."destroyed_at" AND a."id" < b."id");
+
+DELETE FROM "user_destroy_records" a
+USING "user_destroy_records" b
+WHERE a."instance_id" = b."instance_id"
+  AND (
+    a."destroyed_at" < b."destroyed_at"
+    OR (a."destroyed_at" = b."destroyed_at" AND a."id" < b."id")
+  );
+
+CREATE UNIQUE INDEX "user_destroy_records_instance_id_key"
+ON "user_destroy_records"("instance_id");