diff --git a/src/api/router/snapshot_descriptor_upgrade_tests.rs b/src/api/router/snapshot_descriptor_upgrade_tests.rs
index 9cb37b3b..c57bc57b 100644
--- a/src/api/router/snapshot_descriptor_upgrade_tests.rs
+++ b/src/api/router/snapshot_descriptor_upgrade_tests.rs
@@ -85,7 +85,20 @@ async fn captured_87b_descriptor_upgrade_preserves_owners_oids_and_replays_missi
     )
     .await
     .unwrap();
+    let reader = core.begin().await.unwrap();
+    let registrations = reader
+        .query_one_raw(Statement::from_string(
+            DbBackend::Postgres,
+            "SELECT (SELECT count(*) FROM mst2_metadata_namespace) AS namespaces,
+                    (SELECT count(*) FROM mst2_qualified_family_policy) AS policies",
+        ))
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(registrations.try_get::<i64>("", "namespaces").unwrap(), 2);
+    assert_eq!(registrations.try_get::<i64>("", "policies").unwrap(), 1);
     apply_migrations(core, false).await.unwrap();
+    reader.rollback().await.unwrap();
     assert_upgrade_ledgers(core).await;
     assert_eq!(descriptor_matches_stored(&fixture).await, 1);
     assert_eq!(policy(core).await, stamp);
diff --git a/src/api/router/snapshot_reader_retention_tests.rs b/src/api/router/snapshot_reader_retention_tests.rs
index 52890bd7..3feadd29 100644
--- a/src/api/router/snapshot_reader_retention_tests.rs
+++ b/src/api/router/snapshot_reader_retention_tests.rs
@@ -266,14 +266,32 @@ async fn stale_actual_reader_cannot_read_or_finish_a_reissued_uuid() {
         ),
     );
     let app = fixture.app.clone();
-    let pending = tokio::spawn(with_rooted_reader_barriers(
+    let mut pending = tokio::spawn(with_rooted_reader_barriers(
         admitted.clone(),
         resume.clone(),
         async move { app.oneshot(request).await.unwrap() },
     ));
-    tokio::time::timeout(Duration::from_secs(4), admitted.wait())
-        .await
-        .unwrap();
+    // Admission includes a database lock wait of up to five seconds and a
+    // committed owner. Observe an early HTTP failure as well as the barrier.
+    let admission = tokio::time::timeout(Duration::from_secs(30), async {
+        tokio::select! {
+            _ = admitted.wait() => {}
+            response = &mut pending => {
+                let response = response.unwrap();
+                let status = response.status();
+                let body = to_bytes(response.into_body(), 16 * 1024).await.unwrap();
+                panic!(
+                    "reader request ended before its admission barrier: {status}: {}",
+                    String::from_utf8_lossy(&body)
+                );
+            }
+        }
+    })
+    .await;
+    if let Err(error) = admission {
+        pending.abort();
+        panic!("reader admission barrier timed out: {error}");
+    }
     let txn = transaction(&fixture).await;
     let owner=txn.query_one_raw(Statement::from_string(DbBackend::Postgres,
         "SELECT operation_id::text,reader_issuance,to_jsonb(r) AS owner FROM mst2_metadata_reader_operation r WHERE state='ACTIVE'"))
@@ -333,7 +351,7 @@ async fn stale_actual_reader_cannot_read_or_finish_a_reissued_uuid() {
         [old.0.clone().into(),next.into(),source_id.into(),source_root.into(),source_generation.into(),source_certificate.into()])).await.unwrap().is_empty());
     txn.commit().await.unwrap();
     resume.wait().await;
-    let response = tokio::time::timeout(Duration::from_secs(4), pending)
+    let response = tokio::time::timeout(Duration::from_secs(30), pending)
         .await
         .unwrap()
         .unwrap();
diff --git a/src/jupiter/migration/qualified_native_runtime_upgrade.rs b/src/jupiter/migration/qualified_native_runtime_upgrade.rs
index 85cd256b..0aeaba5f 100644
--- a/src/jupiter/migration/qualified_native_runtime_upgrade.rs
+++ b/src/jupiter/migration/qualified_native_runtime_upgrade.rs
@@ -391,8 +391,11 @@ async fn upgrade_to(
             ))
             .await?;
     }
+    // Route admission reads these immutable registrations before waiting for
+    // mono. Exclude concurrent writers and DDL while allowing those reads to
+    // complete without a relation-lock/mono-lock cycle.
     connection.execute_unprepared(&format!(
-        "LOCK TABLE {c}.mst2_metadata_namespace,{c}.mst2_qualified_family_policy IN ACCESS EXCLUSIVE MODE"
+        "LOCK TABLE {c}.mst2_metadata_namespace,{c}.mst2_qualified_family_policy IN SHARE ROW EXCLUSIVE MODE"
     )).await?;
     let policy=connection.query_one_raw(Statement::from_string(DbBackend::Postgres,
         format!("SELECT implementation_fingerprint,expected_shape,authority_catalog FROM {c}.mst2_qualified_family_policy WHERE singleton=1")))