diff --git a/apps/gridcraft/src/main.rs b/apps/gridcraft/src/main.rs
index 5366bdb44..9357d0796 100644
--- a/apps/gridcraft/src/main.rs
+++ b/apps/gridcraft/src/main.rs
@@ -311,15 +311,16 @@ fn main() -> eframe::Result<()> {
     {
         log::warn!("sample {s}: {e}");
     }
-    if session.documents().is_empty() {
-        session.new_workbook();
-    }
     let mut app = SheetApp::new(session, services());
     app.watch_desktop_theme();
     app.start_update_check();
-    app.after_engine(); // Show warnings from the sample.
     let control_port = control_port;
     load_prefs(&mut app);
+    // Stamp the startup workbook's author from the persisted user name.
+    if app.session.documents().is_empty() {
+        app.session.new_workbook();
+    }
+    app.after_engine(); // Show warnings from the sample.
     // Files named on the command line (a double-click on Windows and Linux) open as File › Open
     // opens them: a password-protected one asks for its password, and errors are shown, not
     // only logged. Each replaces the untouched blank Book1, as a file opened from Finder does.
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index d23e6fbd3..3ae4ac95a 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -587,6 +587,7 @@ impl Session {
     pub fn new_workbook(&mut self) -> usize {
         let n = (1..).find(|n| !self.docs.iter().any(|d| d.title == format!("Book{n}") && d.path.is_none())).unwrap_or(1);
         let mut wb = Workbook::new();
+        wb.props.author = self.prefs.user_name.clone();
         for _ in 1..self.prefs.sheets_in_new_workbook.clamp(1, 255) {
             let name = wb.next_sheet_name();
             wb.sheets.push(Arc::new(gridcraft_model::Sheet::new(name)));
diff --git a/crates/engine/tests/it/main.rs b/crates/engine/tests/it/main.rs
index 28d0831e3..20898e152 100644
--- a/crates/engine/tests/it/main.rs
+++ b/crates/engine/tests/it/main.rs
@@ -29,4 +29,5 @@ mod sparse_clear_invalidation;
 mod stored_list_shape;
 mod table_resize_overlap;
 mod table_total_row_last_row;
+mod workbook_author;
 mod wrap_row_height;
diff --git a/crates/engine/tests/it/workbook_author.rs b/crates/engine/tests/it/workbook_author.rs
new file mode 100644
index 000000000..7af8b5d68
--- /dev/null
+++ b/crates/engine/tests/it/workbook_author.rs
@@ -0,0 +1,50 @@
+//! Regression tests for the default author of newly created workbooks.
+
+use gridcraft_engine::{DocState, Session, Trust, io, model::Workbook};
+
+#[test]
+fn new_workbook_stamps_the_configured_user_name_at_creation() {
+    let mut session = Session::new();
+
+    session.prefs.user_name = "Ada Lovelace".into();
+    let first = session.new_workbook();
+
+    assert_eq!(session.documents()[first].wb.props.author, "Ada Lovelace");
+
+    // Changing the preference must not rewrite an existing workbook.
+    session.prefs.user_name = "Grace Hopper".into();
+
+    assert_eq!(session.documents()[first].wb.props.author, "Ada Lovelace");
+
+    // A new workbook uses the preference as it exists at creation.
+    let second = session.new_workbook();
+
+    assert_eq!(session.documents()[second].wb.props.author, "Grace Hopper");
+
+    assert_eq!(session.documents()[first].wb.props.author, "Ada Lovelace");
+}
+
+#[test]
+fn opening_and_resaving_preserves_the_existing_workbook_author() {
+    // An existing XLSX has its own author metadata.
+    let mut source = Workbook::new();
+    source.props.author = "Original Spreadsheet Author".into();
+
+    let bytes = io::save_bytes(&source, "source.xlsx").unwrap();
+    let (opened, _) = io::open_bytes("source.xlsx", &bytes).unwrap();
+
+    let mut session = Session::new();
+    session.prefs.user_name = "Current GridCraft User".into();
+
+    session.add_document(DocState::new(opened, None, "source".into(), Trust::FromFile));
+
+    // Opening an existing workbook must not replace its author.
+    assert_eq!(session.doc().unwrap().wb.props.author, "Original Spreadsheet Author");
+
+    // The original author must survive another XLSX save and reopen.
+    let saved = io::save_bytes(&session.doc().unwrap().wb, "saved.xlsx").unwrap();
+
+    let (reopened, _) = io::open_bytes("saved.xlsx", &saved).unwrap();
+
+    assert_eq!(reopened.props.author, "Original Spreadsheet Author");
+}