diff --git a/control_plane/attachment_service/src/persistence.rs b/control_plane/attachment_service/src/persistence.rs
new file mode 100644
index 0000000000..870b784479
--- /dev/null
+++ b/control_plane/attachment_service/src/persistence.rs
@@ -0,0 +1,13 @@
+/// The attachment service does not store most of its state durably.
+///
+/// The essential things to store durably are:
+/// - generation numbers, as these must always advance monotonically to ensure data safety.
+/// - PlacementPolicy and TenantConfig, as these are set externally.
+struct Persistence {}
+
+/// Parts of TenantState that are stored durably
+struct TenantPersistence {
+    pub(crate) generation: Generation,
+    pub(crate) policy: PlacementPolicy,
+    pub(crate) config: TenantConfig,
+}