diff --git a/crates/domain/src/id.rs b/crates/domain/src/id.rs
index e408193..f7cc745 100644
--- a/crates/domain/src/id.rs
+++ b/crates/domain/src/id.rs
@@ -64,6 +64,10 @@ id_newtype!(
     /// Identifier for an authority record (person, organisation, or place).
     AuthorityId
 );
+id_newtype!(
+    /// Identifier for a catalogue object (or group of objects).
+    ObjectId
+);
 
 #[cfg(test)]
 mod tests {
diff --git a/crates/domain/src/lib.rs b/crates/domain/src/lib.rs
index d5809c4..8c46507 100644
--- a/crates/domain/src/lib.rs
+++ b/crates/domain/src/lib.rs
@@ -4,10 +4,12 @@ mod audit;
 mod authority;
 mod id;
 mod label;
+mod object;
 mod vocabulary;
 
 pub use audit::{AuditAction, AuditActor, AuditEntry, FieldChange, NewAuditEvent};
 pub use authority::{Authority, AuthorityKind, AuthorityRef, NewAuthority};
-pub use id::{AuthorityId, OrgId, TermId, VocabularyId};
+pub use id::{AuthorityId, ObjectId, OrgId, TermId, VocabularyId};
 pub use label::{LocalizedLabel, pick_label};
+pub use object::{CatalogueObject, ObjectInput, Visibility};
 pub use vocabulary::{NewTerm, Term, TermRef, Vocabulary};
diff --git a/crates/domain/src/object.rs b/crates/domain/src/object.rs
new file mode 100644
index 0000000..82fe50e
--- /dev/null
+++ b/crates/domain/src/object.rs
@@ -0,0 +1,98 @@
+use serde::{Deserialize, Serialize};
+use time::{Date, OffsetDateTime};
+
+use crate::ObjectId;
+
+/// Publication state of a catalogue record.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum Visibility {
+    /// Work in progress; not shown anywhere public.
+    #[default]
+    Draft,
+    /// Complete but internal-only.
+    Internal,
+    /// Published; eligible for the public API.
+    Public,
+}
+
+impl Visibility {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Visibility::Draft => "draft",
+            Visibility::Internal => "internal",
+            Visibility::Public => "public",
+        }
+    }
+
+    pub fn from_db(s: &str) -> Option<Self> {
+        match s {
+            "draft" => Some(Visibility::Draft),
+            "internal" => Some(Visibility::Internal),
+            "public" => Some(Visibility::Public),
+            _ => None,
+        }
+    }
+}
+
+/// The mutable inventory-minimum fields of a catalogue object.
+#[derive(Debug, Clone, PartialEq)]
+pub struct ObjectInput {
+    pub object_number: String,
+    pub object_name: String,
+    pub number_of_objects: i32,
+    pub brief_description: Option<String>,
+    pub current_location: Option<String>,
+    pub current_owner: Option<String>,
+    pub recorder: Option<String>,
+    pub recording_date: Option<Date>,
+    pub visibility: Visibility,
+}
+
+/// A catalogue object (or group of objects), read back from storage.
+#[derive(Debug, Clone, PartialEq)]
+pub struct CatalogueObject {
+    pub id: ObjectId,
+    pub object_number: String,
+    pub object_name: String,
+    pub number_of_objects: i32,
+    pub brief_description: Option<String>,
+    pub current_location: Option<String>,
+    pub current_owner: Option<String>,
+    pub recorder: Option<String>,
+    pub recording_date: Option<Date>,
+    pub visibility: Visibility,
+    pub created_at: OffsetDateTime,
+    pub updated_at: OffsetDateTime,
+}
+
+impl CatalogueObject {
+    /// The mutable fields as an [`ObjectInput`] (used to diff against an update).
+    pub fn to_input(&self) -> ObjectInput {
+        ObjectInput {
+            object_number: self.object_number.clone(),
+            object_name: self.object_name.clone(),
+            number_of_objects: self.number_of_objects,
+            brief_description: self.brief_description.clone(),
+            current_location: self.current_location.clone(),
+            current_owner: self.current_owner.clone(),
+            recorder: self.recorder.clone(),
+            recording_date: self.recording_date,
+            visibility: self.visibility,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn visibility_round_trips_and_defaults_to_draft() {
+        for v in [Visibility::Draft, Visibility::Internal, Visibility::Public] {
+            assert_eq!(Visibility::from_db(v.as_str()), Some(v));
+        }
+        assert_eq!(Visibility::from_db("secret"), None);
+        assert_eq!(Visibility::default(), Visibility::Draft);
+    }
+}