diff --git a/crates/engine/src/components.rs b/crates/engine/src/components.rs
index f011625d..c0612bcd 100644
--- a/crates/engine/src/components.rs
+++ b/crates/engine/src/components.rs
@@ -116,6 +116,23 @@ pub fn inside_instance(doc: &Document, id: NodeId) -> bool {
     enclosing_instance(doc, id).is_some()
 }
 
+/// Mark the `modes` override on layers inside instances whose variable modes differ from their
+/// main layer's, for files from before `modes` was an override group. Copies follow their main
+/// layer's modes, so a layer on other modes chose them itself.
+pub fn mark_layer_modes(doc: &mut Document) {
+    let chose: Vec<NodeId> = doc
+        .nodes()
+        .filter(|n| !n.overrides.contains("modes") && n.source.and_then(|s| doc.node(s)).is_some_and(|m| m.var_modes != n.var_modes))
+        .map(|n| n.id)
+        .filter(|id| inside_instance(doc, *id))
+        .collect();
+    for id in chose {
+        if let Some(n) = doc.node_mut(id) {
+            n.overrides.insert("modes".into());
+        }
+    }
+}
+
 /// The slot property frame `id` stands for (its name and preferred components): a frame bound to
 /// a slot property of its component, or an instance's copy of one (followed through its sources).
 pub fn slot_def(doc: &Document, id: NodeId) -> Option<(&str, &[NodeId])> {
diff --git a/crates/engine/src/instance_modes_tests.rs b/crates/engine/src/instance_modes_tests.rs
index 0836048f..43de3ca4 100644
--- a/crates/engine/src/instance_modes_tests.rs
+++ b/crates/engine/src/instance_modes_tests.rs
@@ -175,3 +175,22 @@ fn a_mode_set_on_an_icon_inside_a_placed_instance_survives_main_edits() {
     run(&mut s, "component.resetInstance", json!({"ids": [placed]}));
     assert_eq!(fill(&s, icon), "FF0000", "reset all brings back the main's mode");
 }
+
+#[test]
+fn a_file_from_before_modes_were_overrides_keeps_the_modes_chosen_inside_its_instances() {
+    let mut s = Session::new();
+    let (button, _, nested) = modal(&mut s);
+    // Saved before `modes` was an override group: the copy has its mode but no marker.
+    s.doc_mut().unwrap().node_mut(nested).unwrap().overrides.remove("modes");
+    let path = std::env::temp_dir().join(format!("figcraft-instance-modes-{}.figcraft", std::process::id()));
+    let p = path.to_string_lossy().into_owned();
+    run(&mut s, "file.saveAs", json!({"path": p}));
+    let mut s = Session::new();
+    run(&mut s, "file.open", json!({"path": p}));
+    let _ = std::fs::remove_file(&path);
+    let doc = s.doc().unwrap();
+    assert!(doc.node(nested).unwrap().overrides.contains("modes"), "opening it marks the mode the copy chose");
+    assert!(doc.nodes().filter(|n| n.id != nested).all(|n| !n.overrides.contains("modes")), "layers on their main's modes stay unmarked");
+    run(&mut s, "node.set", json!({"ids": [button], "layout": "horizontal"}));
+    assert_eq!(fill(&s, nested), "0000FF", "a rebuild keeps it");
+}
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index 79e7be0d..d878d6ab 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -413,6 +413,7 @@ impl DocState {
         }
         doc.link_layer_text_styles();
         cmd::styles::apply_paint_bindings_on_load(&mut doc);
+        components::mark_layer_modes(&mut doc);
         // Initial import settlement belongs to the saved baseline, not the user's first edit.
         let page = doc.current_page.filter(|p| doc.pages.contains(p)).or_else(|| doc.first_page()).unwrap_or(NodeId(0));
         let doc = Arc::new(doc);
diff --git a/crates/engine/src/library.rs b/crates/engine/src/library.rs
index 26863561..9740182c 100644
--- a/crates/engine/src/library.rs
+++ b/crates/engine/src/library.rs
@@ -553,11 +553,18 @@ fn stat(_path: &str) -> std::result::Result<Stamp, String> {
     Err(NO_FILES.into())
 }
 
+/// A library read from a file or a server, with the modes chosen inside its instances marked when
+/// it was published before they were overrides ([`crate::components::mark_layer_modes`]).
+pub(crate) fn settled(mut lib: PublishedLibrary) -> PublishedLibrary {
+    crate::components::mark_layer_modes(Arc::make_mut(&mut lib.doc));
+    lib
+}
+
 #[cfg(not(target_arch = "wasm32"))]
 fn read_file(path: &str) -> std::result::Result<PublishedLibrary, String> {
     let f = crate::file_access::open(path).map_err(|e| e.to_string())?;
     match figcraft_format::read_library(std::io::BufReader::new(f)) {
-        Ok(Some(lib)) => Ok(lib),
+        Ok(Some(lib)) => Ok(settled(lib)),
         Ok(None) => Err(format!("{path} has no published library: open it and publish it first (Libraries ▸ Publish library…)")),
         Err(e) => Err(format!("{path}: {e}")),
     }
diff --git a/crates/engine/src/library_server.rs b/crates/engine/src/library_server.rs
index 99d5f29a..10852b5f 100644
--- a/crates/engine/src/library_server.rs
+++ b/crates/engine/src/library_server.rs
@@ -53,7 +53,7 @@ pub fn archive(lib: &PublishedLibrary) -> Result<Vec<u8>> {
 /// The library in an archive from a server (untrusted: read with the library file's limits).
 pub fn read_archive(bytes: &[u8]) -> std::result::Result<PublishedLibrary, String> {
     match figcraft_format::read_library(Cursor::new(bytes)) {
-        Ok(Some(lib)) => Ok(lib),
+        Ok(Some(lib)) => Ok(crate::library::settled(lib)),
         Ok(None) => Err("the server sent a file without a library".into()),
         Err(e) => Err(format!("the server sent a library that can't be read ({e})")),
     }
diff --git a/crates/engine/src/library_variables_tests.rs b/crates/engine/src/library_variables_tests.rs
index 7104164b..b4a4171a 100644
--- a/crates/engine/src/library_variables_tests.rs
+++ b/crates/engine/src/library_variables_tests.rs
@@ -345,32 +345,42 @@ fn library_style_bindings_ignore_unrelated_local_variables() {
     let _ = std::fs::remove_dir_all(&d);
 }
 
+/// A library "Modal" holding a Button instance whose icon copy is on mode Dark: (the Button main,
+/// the icon copy in Modal).
+fn nested_mode_kit(lib: &mut Session) -> (NodeId, NodeId) {
+    theme(lib);
+    let f = idv(&ex(lib, "frame.create", json!({"x": 0, "y": 0, "width": 20, "height": 20, "name": "Icon"})));
+    ex(lib, "variable.bind", json!({"ids": [f], "field": "fill", "variable": "primary"}));
+    let icon = idv(&ex(lib, "component.create", json!({"ids": [f]})));
+    let b = idv(&ex(lib, "frame.create", json!({"x": 100, "y": 0, "width": 60, "height": 40, "name": "Button"})));
+    ex(lib, "instance.create", json!({"component": icon, "x": 10, "y": 10, "parent": b}));
+    let button = idv(&ex(lib, "component.create", json!({"ids": [b]})));
+    let m = idv(&ex(lib, "frame.create", json!({"x": 300, "y": 0, "width": 200, "height": 100, "name": "Modal"})));
+    let close = idv(&ex(lib, "instance.create", json!({"component": button, "x": 10, "y": 10, "parent": m})));
+    let nested = lib.doc().unwrap().node(close).unwrap().children[0];
+    ex(lib, "variable.setMode", json!({"ids": [nested], "collection": "Theme", "mode": "Dark"}));
+    ex(lib, "component.create", json!({"ids": [m]}));
+    (button, nested)
+}
+
+/// The icon inside the Button inside library Modal instance `inst`.
+fn modal_icon(s: &Session, inst: NodeId) -> NodeId {
+    let doc = s.doc().unwrap();
+    doc.node(doc.node(inst).unwrap().children[0]).unwrap().children[0]
+}
+
 #[test]
 fn modes_set_inside_nested_instances_come_along() {
     let d = dir("nested-modes");
     let lib_path = path_str(&d.join("kit.figcraft"));
     let mut lib = Session::new();
-    theme(&mut lib);
-    let f = idv(&ex(&mut lib, "frame.create", json!({"x": 0, "y": 0, "width": 20, "height": 20, "name": "Icon"})));
-    ex(&mut lib, "variable.bind", json!({"ids": [f], "field": "fill", "variable": "primary"}));
-    let icon = idv(&ex(&mut lib, "component.create", json!({"ids": [f]})));
-    let b = idv(&ex(&mut lib, "frame.create", json!({"x": 100, "y": 0, "width": 60, "height": 40, "name": "Button"})));
-    ex(&mut lib, "instance.create", json!({"component": icon, "x": 10, "y": 10, "parent": b}));
-    let button = idv(&ex(&mut lib, "component.create", json!({"ids": [b]})));
-    let m = idv(&ex(&mut lib, "frame.create", json!({"x": 300, "y": 0, "width": 200, "height": 100, "name": "Modal"})));
-    let close = idv(&ex(&mut lib, "instance.create", json!({"component": button, "x": 10, "y": 10, "parent": m})));
-    let nested = lib.doc().unwrap().node(close).unwrap().children[0];
-    ex(&mut lib, "variable.setMode", json!({"ids": [nested], "collection": "Theme", "mode": "Dark"}));
-    ex(&mut lib, "component.create", json!({"ids": [m]}));
+    let (button, _) = nested_mode_kit(&mut lib);
     let lid = publish_to(&mut lib, &lib_path);
 
     let mut s = Session::new();
     ex(&mut s, "library.add", json!({"path": lib_path}));
     let inst = idv(&ex(&mut s, "library.place", json!({"library": lid, "component": "Modal", "x": 0, "y": 0})));
-    let copy = |s: &Session| {
-        let doc = s.doc().unwrap();
-        doc.node(doc.node(inst).unwrap().children[0]).unwrap().children[0]
-    };
+    let copy = |s: &Session| modal_icon(s, inst);
     assert_eq!(fill(&s, copy(&s)), "FFFFFF", "the Dark mode set on the nested icon comes along");
     // An update that rebuilds the Button copies keeps it too.
     ex(&mut lib, "node.set", json!({"ids": [button], "layout": "horizontal"}));
@@ -380,3 +390,21 @@ fn modes_set_inside_nested_instances_come_along() {
     healthy(&s);
     let _ = std::fs::remove_dir_all(&d);
 }
+
+#[test]
+fn a_library_published_before_modes_were_overrides_keeps_the_modes_set_inside_nested_instances() {
+    let d = dir("nested-modes-old");
+    let lib_path = path_str(&d.join("kit.figcraft"));
+    let mut lib = Session::new();
+    let (_, nested) = nested_mode_kit(&mut lib);
+    // Published before `modes` was an override group: the copy has its mode but no marker.
+    lib.doc_mut().unwrap().node_mut(nested).unwrap().overrides.remove("modes");
+    let lid = publish_to(&mut lib, &lib_path);
+
+    let mut s = Session::new();
+    ex(&mut s, "library.add", json!({"path": lib_path}));
+    let inst = idv(&ex(&mut s, "library.place", json!({"library": lid, "component": "Modal", "x": 0, "y": 0})));
+    assert_eq!(fill(&s, modal_icon(&s, inst)), "FFFFFF", "the Dark mode comes along");
+    healthy(&s);
+    let _ = std::fs::remove_dir_all(&d);
+}