diff --git a/crates/ui-egui/src/panels/viewer.rs b/crates/ui-egui/src/panels/viewer.rs
index 2e3dc9be0..f150cfc08 100644
--- a/crates/ui-egui/src/panels/viewer.rs
+++ b/crates/ui-egui/src/panels/viewer.rs
@@ -1255,6 +1255,39 @@ fn phase_dragstart(app: &mut EffectcraftApp, ui: &mut egui::Ui, ectx: &EvalCtx,
     v.puppet_layers = puppet_layers;
 }
 
+/// Auto-pan (#999): a mask vertex, tangent or Pen drag held at (or past) the edge of the view
+/// pans it, as in After Effects, so the point moves on past what was visible. Returns the map
+/// of the panned view.
+fn edge_pan(app: &mut EffectcraftApp, ctx: &egui::Context, g: &Gesture, map: ViewerMap, pos: Pos2) -> ViewerMap {
+    if !matches!(g, Gesture::Vertices { .. } | Gesture::Tangent { .. } | Gesture::Pen { .. }) {
+        return map;
+    }
+    let d = edge_pan_speed(map.area, pos) * ctx.input(|i| i.stable_dt).min(0.1);
+    if d == egui::Vec2::ZERO {
+        return map;
+    }
+    app.ui.viewer.pan = [app.ui.viewer.pan[0] + d.x, app.ui.viewer.pan[1] + d.y];
+    ctx.request_repaint();
+    ViewerMap { origin: map.origin + d, ..map }
+}
+
+/// How fast (points per second, per axis) the view pans under a drag at `pos`: within 24 points
+/// of an edge of `area`, or past it, toward that edge and faster the further out.
+fn edge_pan_speed(area: Rect, pos: Pos2) -> egui::Vec2 {
+    const ZONE: f32 = 24.0;
+    let axis = |p: f32, lo: f32, hi: f32| {
+        let depth = if p < lo + ZONE {
+            lo + ZONE - p
+        } else if p > hi - ZONE {
+            hi - ZONE - p
+        } else {
+            0.0
+        };
+        (depth / ZONE).clamp(-3.0, 3.0) * 400.0
+    };
+    vec2(axis(pos.x, area.min.x, area.max.x), axis(pos.y, area.min.y, area.max.y))
+}
+
 fn phase_drag(app: &mut EffectcraftApp, ui: &mut egui::Ui, ectx: &EvalCtx, resp: &egui::Response, v: &mut Vw<'_>) {
     let t = v.t;
     let zoom = v.zoom;
@@ -1265,6 +1298,7 @@ fn phase_drag(app: &mut EffectcraftApp, ui: &mut egui::Ui, ectx: &EvalCtx, resp:
     let painter = v.painter.clone();
     let gesture: Option<Gesture> = ui.data(|d| d.get_temp(gid));
     if let (Some(g), Some(pos)) = (gesture.clone(), resp.interact_pointer_pos()) {
+        let map = edge_pan(app, &ctx, &g, map, pos);
         let cpt = map.to_comp(pos);
         let merge = format!("viewer-drag-{}", ui.data(|d| d.get_temp::<u64>(egui::Id::unique("viewer-drag-n")).unwrap_or(0)));
         match g {
diff --git a/crates/ui-egui/src/panels/viewer/tests.rs b/crates/ui-egui/src/panels/viewer/tests.rs
index cb5bffe65..f9d3ef2f4 100644
--- a/crates/ui-egui/src/panels/viewer/tests.rs
+++ b/crates/ui-egui/src/panels/viewer/tests.rs
@@ -139,3 +139,15 @@ fn gizmo_segments_clip_at_the_near_plane() {
     assert!(s[1][0] > 10.0 && s[1][0].is_finite(), "toward the camera it grows, never flips: {s:?}");
     assert!(project_segment(&pc, vec3(0.0, 0.0, -200.0), vec3(0.0, 0.0, -300.0)).is_none());
 }
+
+/// #999: a vertex drag pans the view only near or past the edge, toward it, faster further out.
+#[test]
+fn edge_pan_speed_moves_toward_the_edge() {
+    let area = Rect::from_min_max(pos2(100.0, 50.0), pos2(900.0, 650.0));
+    assert_eq!(edge_pan_speed(area, pos2(500.0, 350.0)), egui::Vec2::ZERO);
+    let left = edge_pan_speed(area, pos2(105.0, 350.0));
+    assert!(left.x > 0.0 && left.y == 0.0, "near the left edge the view moves right to show more: {left:?}");
+    assert!(edge_pan_speed(area, pos2(20.0, 350.0)).x > left.x, "faster past the edge");
+    let corner = edge_pan_speed(area, pos2(950.0, 700.0));
+    assert!(corner.x < 0.0 && corner.y < 0.0, "{corner:?}");
+}
diff --git a/crates/ui-egui/tests/it/ui_viewer.rs b/crates/ui-egui/tests/it/ui_viewer.rs
index fb7557c83..41cf5fe43 100644
--- a/crates/ui-egui/tests/it/ui_viewer.rs
+++ b/crates/ui-egui/tests/it/ui_viewer.rs
@@ -831,6 +831,48 @@ fn shift_drag_keeps_a_mask_vertex_to_one_axis() {
     assert!(free[0] > shifted[0] && free[1] > shifted[1], "without Shift both axes move: {shifted:?} -> {free:?}");
 }
 
+/// #999: a mask vertex dragged against the edge of the Composition panel pans the view, and the
+/// vertex keeps moving while the pointer is held there, as in After Effects.
+#[test]
+fn a_vertex_held_at_the_viewer_edge_pans_the_view() {
+    let mut h = harness();
+    let plate = layer_id(&h, "Plate");
+    let corners = [[100.0, 60.0], [500.0, 60.0], [500.0, 300.0], [100.0, 300.0]];
+    let mask = {
+        let s = &mut h.state_mut().session;
+        s.execute("layer.select", json!({"layers": [plate]})).unwrap();
+        let m = s.execute("mask.new", json!({"layer": plate, "vertices": corners, "closed": true})).unwrap()["mask"].as_u64().unwrap();
+        s.execute("mask.selectVertices", json!({"vertices": [{"layer": plate, "mask": m, "index": 0}]})).unwrap();
+        m
+    };
+    h.run_steps(2);
+    let pan0 = h.state().ui.viewer.pan;
+    let from = rect(&h, &format!("viewer.mask.{mask}.vertex.0")).center();
+    let edge = pos2(2.0, from.y);
+    h.input_mut().events.push(Event::PointerMoved(from));
+    h.input_mut().events.push(Event::PointerButton { pos: from, button: egui::PointerButton::Primary, pressed: true, modifiers: Default::default() });
+    h.step();
+    for i in 1..=6 {
+        h.input_mut().events.push(Event::PointerMoved(from + (edge - from) * (i as f32 / 6.0)));
+        h.step();
+    }
+    let reached = mask_path(&h, "Plate").vertices[0];
+    for _ in 0..20 {
+        h.step();
+    }
+    h.input_mut().events.push(Event::PointerButton { pos: edge, button: egui::PointerButton::Primary, pressed: false, modifiers: Default::default() });
+    h.run_steps(2);
+    let pan = h.state().ui.viewer.pan;
+    assert!(pan[0] > pan0[0] && pan[1] == pan0[1], "the view panned right to show more on the left: {pan0:?} -> {pan:?}");
+    let after = mask_path(&h, "Plate").vertices[0];
+    assert!(after[0] < reached[0], "the vertex kept moving left with the view: {reached:?} -> {after:?}");
+    // Back inside the view, nothing pans.
+    let still = h.state().ui.viewer.pan;
+    let mid = rect(&h, "viewer.comp").center();
+    drag(&mut h, mid, mid + vec2(5.0, 0.0));
+    assert_eq!(h.state().ui.viewer.pan, still);
+}
+
 /// #1769: a hidden masked layer keeps its mask path and vertices, and they remain editable.
 #[test]
 fn hidden_masked_layer_keeps_its_mask_path_editable() {