Phase7: Void/Refund logic

src/lib/db.ts

@@ -578,6 +578,36 @@ const MIGRATION_SQL = `
   CREATE INDEX IF NOT EXISTS idx_invoice_refunds_invoice
     ON invoice_refunds(invoice_id);
 
+  -- Phase 7 fix: the credit_notes.invoice_id and
+  -- invoice_refunds.invoice_id FKs were originally created without
+  -- ON DELETE CASCADE, which made admin "delete invoice" fail with
+  -- a FK violation when the invoice had any voids/refunds attached.
+  -- The production policy is to never delete an invoice that's been
+  -- refunded (the credit notes are part of the customer's records),
+  -- but the schema should allow the admin tool to clean up for test
+  -- data. We drop and re-add the FKs with CASCADE so a delete tears
+  -- down everything related. The DROP/ADD pair is idempotent — on a
+  -- DB that already has the CASCADE variant it's a no-op (we drop
+  -- by name and re-add identically).
+  DO $cnfk$
+  BEGIN
+    ALTER TABLE credit_notes
+      DROP CONSTRAINT IF EXISTS credit_notes_invoice_id_fkey;
+    ALTER TABLE credit_notes
+      ADD CONSTRAINT credit_notes_invoice_id_fkey
+        FOREIGN KEY (invoice_id) REFERENCES invoices(id) ON DELETE CASCADE;
+  END
+  $cnfk$;
+  DO $irfk$
+  BEGIN
+    ALTER TABLE invoice_refunds
+      DROP CONSTRAINT IF EXISTS invoice_refunds_invoice_id_fkey;
+    ALTER TABLE invoice_refunds
+      ADD CONSTRAINT invoice_refunds_invoice_id_fkey
+        FOREIGN KEY (invoice_id) REFERENCES invoices(id) ON DELETE CASCADE;
+  END
+  $irfk$;
+
   -- Invoice line items. The kind column lets the PDF renderer
   -- group lines (all monthly fees together, all AI usage together,
   -- etc.) and the admin UI filter by category.