diff --git a/crates/db/tests/object_fields.rs b/crates/db/tests/object_fields.rs
index 7c14c53..8d8a24f 100644
--- a/crates/db/tests/object_fields.rs
+++ b/crates/db/tests/object_fields.rs
@@ -163,3 +163,212 @@ async fn unknown_field_and_type_mismatch_are_rejected(pool: PgPool) {
     ));
     drop(tx);
 }
+
+#[sqlx::test]
+async fn authority_field_enforces_kind(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(
+        &db,
+        "maker",
+        FieldType::Authority {
+            kind: Some(domain::AuthorityKind::Person),
+        },
+    )
+    .await;
+
+    let mut tx = db.pool().begin().await.unwrap();
+    let person = db::authority::create_authority(
+        &mut tx,
+        &domain::NewAuthority {
+            kind: domain::AuthorityKind::Person,
+            external_uri: None,
+            labels: label("Carl"),
+        },
+    )
+    .await
+    .unwrap();
+    let place = db::authority::create_authority(
+        &mut tx,
+        &domain::NewAuthority {
+            kind: domain::AuthorityKind::Place,
+            external_uri: None,
+            labels: label("Stockholm"),
+        },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let ok = serde_json::json!({ "maker": person.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, ok.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let bad = serde_json::json!({ "maker": place.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::Unresolved { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn term_from_wrong_vocabulary_is_rejected(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    let material = vocab::create_vocabulary(db.pool(), "material")
+        .await
+        .unwrap();
+    let technique = vocab::create_vocabulary(db.pool(), "technique")
+        .await
+        .unwrap();
+    define(
+        &db,
+        "material",
+        FieldType::Term {
+            vocabulary_id: material.id,
+        },
+    )
+    .await;
+
+    // a real term, but in the WRONG vocabulary
+    let mut tx = db.pool().begin().await.unwrap();
+    let other = vocab::add_term(
+        &mut tx,
+        &domain::NewTerm {
+            vocabulary_id: technique.id,
+            external_uri: None,
+            labels: label("forged"),
+        },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let bad = serde_json::json!({ "material": other.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::Unresolved { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn localized_text_round_trips(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "title", FieldType::LocalizedText).await;
+
+    let values = serde_json::json!({ "title": { "sv": "Vas", "en": "Vase" } });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert_eq!(obj.fields["title"]["sv"], "Vas");
+    assert_eq!(obj.fields["title"]["en"], "Vase");
+
+    let bad = serde_json::json!({ "title": { "sv": 5 } });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::TypeMismatch { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn replace_semantics_remove_a_field_and_audit_it(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+    define(&db, "year", FieldType::Integer).await;
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        id,
+        serde_json::json!({ "comments": "x", "year": 1850 })
+            .as_object()
+            .unwrap(),
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        id,
+        serde_json::json!({ "comments": "x" }).as_object().unwrap(),
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert!(obj.fields.get("year").is_none());
+
+    let history = audit::history_for(db.pool(), "object", id.to_uuid())
+        .await
+        .unwrap();
+    let last = history.last().unwrap();
+    let year = last
+        .changes
+        .iter()
+        .find(|c| c.field == "year")
+        .expect("year removal recorded");
+    assert!(year.before.is_some());
+    assert!(year.after.is_none());
+}
+
+#[sqlx::test]
+async fn no_op_set_records_no_audit(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+
+    let values = serde_json::json!({ "comments": "x" });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let before = audit::history_for(db.pool(), "object", id.to_uuid())
+        .await
+        .unwrap()
+        .len();
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let after = audit::history_for(db.pool(), "object", id.to_uuid())
+        .await
+        .unwrap()
+        .len();
+    assert_eq!(before, after, "a no-op set must not add an audit entry");
+}
+
+#[sqlx::test]
+async fn set_on_missing_object_errors(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let mut tx = db.pool().begin().await.unwrap();
+    let err = catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        domain::ObjectId::new(),
+        serde_json::json!({}).as_object().unwrap(),
+    )
+    .await;
+    assert!(matches!(err, Err(FieldError::ObjectNotFound)));
+}