diff --git a/crates/ui-egui/tests/it/main.rs b/crates/ui-egui/tests/it/main.rs
index 6b4c08912..8573f83b2 100644
--- a/crates/ui-egui/tests/it/main.rs
+++ b/crates/ui-egui/tests/it/main.rs
@@ -68,6 +68,7 @@ mod ui_text_edit;
 mod ui_text_range_handles;
 mod ui_theme_favorites;
 mod ui_time_zoom_controls;
+mod ui_timeline_audio_levels;
 mod ui_timeline_effect_label;
 mod ui_timeline_pan;
 mod ui_timeline_shapes;
diff --git a/crates/ui-egui/tests/it/ui_timeline_audio_levels.rs b/crates/ui-egui/tests/it/ui_timeline_audio_levels.rs
new file mode 100644
index 000000000..e1c626489
--- /dev/null
+++ b/crates/ui-egui/tests/it/ui_timeline_audio_levels.rs
@@ -0,0 +1,107 @@
+//! Audio Levels' channel link in the Timeline (#2485): off by default; linked, an edit to one
+//! channel moves the other by the same dB, so the stereo balance stays, typed or scrubbed, on a
+//! static or animated property, and one Undo takes it back.
+
+use effectcraft_engine::Session;
+use effectcraft_engine::project::LayerId;
+use effectcraft_ui_egui::EffectcraftApp;
+use egui::{Event, Key, Modifiers, PointerButton, Pos2, pos2, vec2};
+use egui_kittest::Harness;
+use serde_json::json;
+
+fn center(h: &Harness<'_, EffectcraftApp>, id: &str) -> Pos2 {
+    let e = h.state().auto.find(id).unwrap_or_else(|| panic!("no {id}"));
+    pos2(e.rect[0] + e.rect[2] / 2.0, e.rect[1] + e.rect[3] / 2.0)
+}
+
+/// Press on `from`, move to `to` in `steps`, release there.
+fn drag(h: &mut Harness<'_, EffectcraftApp>, from: Pos2, to: Pos2, steps: u32) {
+    h.input_mut().events.push(Event::PointerMoved(from));
+    h.step();
+    h.input_mut().events.push(Event::PointerButton { pos: from, button: PointerButton::Primary, pressed: true, modifiers: Modifiers::NONE });
+    h.step();
+    for k in 1..=steps {
+        h.input_mut().events.push(Event::PointerMoved(from + (to - from) * (k as f32 / steps as f32)));
+        h.step();
+    }
+    h.input_mut().events.push(Event::PointerButton { pos: to, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE });
+    h.run_steps(3);
+}
+
+fn click(h: &mut Harness<'_, EffectcraftApp>, id: &str) {
+    let p = center(h, id);
+    drag(h, p, p, 1);
+}
+
+fn type_value(h: &mut Harness<'_, EffectcraftApp>, id: &str, v: &str) {
+    click(h, id);
+    h.input_mut().events.push(Event::Text(v.into()));
+    h.step();
+    h.input_mut().events.push(Event::Key { key: Key::Enter, physical_key: None, pressed: true, repeat: false, modifiers: Modifiers::NONE });
+    h.run_steps(3);
+}
+
+#[test]
+fn linked_audio_levels_move_both_channels_by_the_same_db() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "Sound", "width": 64, "height": 36, "duration": 4})).unwrap();
+    s.execute("comp.new", json!({"name": "Main", "width": 320, "height": 180, "duration": 4})).unwrap();
+    let l = s.execute("layer.addItem", json!({"item": "Sound"})).unwrap()["layer"].as_u64().unwrap();
+    let uid = s.active_comp().unwrap().layer(LayerId(l)).unwrap().props.prop("audio/levels").unwrap().uid;
+    s.execute("prop.set", json!({"layer": l, "path": "audio/levels", "value": [-6.0, -12.0]})).unwrap();
+    let mut h = Harness::builder().with_size(vec2(1600.0, 1000.0)).build_eframe(|_| EffectcraftApp::new(s));
+    h.state_mut().ui.timeline.open_layers.insert(l);
+    h.state_mut().ui.timeline.layer_reveal.insert(l, vec!["props".into()]);
+    h.state_mut().ui.timeline.reveal_props.insert(uid);
+    h.run_steps(3);
+    let levels =
+        |h: &Harness<'_, EffectcraftApp>| h.state().session.active_comp().unwrap().layer(LayerId(l)).unwrap().props.prop("audio/levels").unwrap().clone();
+    let set = |h: &mut Harness<'_, EffectcraftApp>, v: [f64; 2]| {
+        h.state_mut().session.execute("prop.set", json!({"layer": l, "path": "audio/levels", "value": v})).unwrap();
+        h.run_steps(2);
+    };
+    let undo = |h: &mut Harness<'_, EffectcraftApp>| {
+        h.state_mut().session.execute("edit.undo", json!({})).unwrap();
+        h.run_steps(2);
+    };
+    let (left, right, link) = (format!("timeline.prop.{uid}.value.0"), format!("timeline.prop.{uid}.value.1"), format!("timeline.prop.{uid}.link"));
+    assert_eq!(h.state().auto.find(&link).unwrap().label, "Link Channels");
+
+    type_value(&mut h, &left, "-3");
+    assert_eq!(levels(&h).value.components(), vec![-3.0, -12.0], "unlinked by default, one channel moves alone");
+    set(&mut h, [-6.0, -12.0]);
+
+    click(&mut h, &link);
+    type_value(&mut h, &left, "-3");
+    assert_eq!(levels(&h).value.components(), vec![-3.0, -9.0], "linked, both rise 3 dB and keep their 6 dB balance");
+    undo(&mut h);
+    assert_eq!(levels(&h).value.components(), vec![-6.0, -12.0], "one Undo takes back both channels");
+
+    type_value(&mut h, &right, "0");
+    assert_eq!(levels(&h).value.components(), vec![6.0, 0.0], "the right channel leads just the same");
+    set(&mut h, [0.0, 0.0]);
+    type_value(&mut h, &left, "-6");
+    assert_eq!(levels(&h).value.components(), vec![-6.0, -6.0], "equal channels at 0 dB stay equal");
+
+    set(&mut h, [-6.0, -12.0]);
+    let from = center(&h, &left);
+    drag(&mut h, from, from + vec2(30.0, 0.0), 6);
+    let c = levels(&h).value.components();
+    assert!(c[0] > -6.0, "the scrub raised the left channel: {c:?}");
+    assert!((c[0] - c[1] - 6.0).abs() < 1e-9, "a linked scrub keeps the balance: {c:?}");
+    undo(&mut h);
+    assert_eq!(levels(&h).value.components(), vec![-6.0, -12.0], "one Undo takes back the whole scrub");
+
+    // Animated: the edit at the current time changes that key's two channels together.
+    h.state_mut().session.execute("prop.addKey", json!({"layer": l, "path": "audio/levels", "time": 0.0, "value": [-6.0, -12.0]})).unwrap();
+    h.state_mut().session.execute("prop.addKey", json!({"layer": l, "path": "audio/levels", "time": 1.0, "value": [0.0, 0.0]})).unwrap();
+    h.run_steps(2);
+    type_value(&mut h, &left, "-10");
+    let keys: Vec<Vec<f64>> = levels(&h).keys.iter().map(|k| k.value.components()).collect();
+    assert_eq!(keys, vec![vec![-10.0, -16.0], vec![0.0, 0.0]], "the key at the current time moves both channels");
+
+    click(&mut h, &link);
+    type_value(&mut h, &left, "-4");
+    let keys: Vec<Vec<f64>> = levels(&h).keys.iter().map(|k| k.value.components()).collect();
+    assert_eq!(keys[0], vec![-4.0, -16.0], "unlinked again, the right channel stays");
+}