Refuse orphan state without Domain Store authority

crates/lazaret-state-anchor/src/lib.rs

@@ -425,6 +425,33 @@ pub enum StateAnchorResetScope<'a> {
     Selected(&'a Path),
 }
 
+/// Proves that no physical State Anchor exists under either retained Domain authority.
+///
+/// # Errors
+/// Refuses changed authority, links, inaccessible paths, or any persistent or runtime anchor.
+pub fn require_state_anchor_absent(
+    configuration: &ResolvedDomainConfiguration,
+) -> Result<(), StateAnchorError> {
+    for plan in [
+        configuration.persistent_domain_root(),
+        configuration.runtime_domain_root(),
+    ] {
+        let root = plan
+            .open_authority()
+            .map_err(|_| StateAnchorError::InvalidLayout("Domain authority changed"))?;
+        match open_directory(&root, Path::new("state-anchor")) {
+            Ok(_) => {
+                return Err(StateAnchorError::InvalidLayout(
+                    "State Anchor exists without Domain Store authority",
+                ));
+            }
+            Err(StateAnchorError::Io(error)) if error.kind() == io::ErrorKind::NotFound => {}
+            Err(error) => return Err(error),
+        }
+    }
+    Ok(())
+}
+
 /// Refuses an orphan reset quarantine without opening transient mount paths.
 ///
 /// # Errors