diff --git a/services/mam-api/src/db/migrations/015-add-growing-retention-setting.sql b/services/mam-api/src/db/migrations/015-add-growing-retention-setting.sql
new file mode 100644
index 0000000..a2db10f
--- /dev/null
+++ b/services/mam-api/src/db/migrations/015-add-growing-retention-setting.sql
@@ -0,0 +1,6 @@
+-- Migration 015: Add growing_retention_days to settings table
+-- Default 30 days. ON CONFLICT DO NOTHING is idempotent -- safe to re-run.
+
+INSERT INTO settings (key, value)
+VALUES ('growing_retention_days', '30')
+ON CONFLICT (key) DO NOTHING;