diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 9b931d0d..68de1341 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -5841,6 +5841,204 @@ fn box_of(s: &mut Session, id: u64) -> serde_json::Value {
     s.execute("shape.inspect", &json!({"id": id})).unwrap()["box"].clone()
 }
 
+/// Two selected boxes with different sizes and aligned right edges, on a blank slide.
+fn resize_selection_scene() -> (Session, [u64; 2]) {
+    let mut s = session();
+    s.execute("slide.new", &json!({"layout": "blank"})).unwrap();
+    s.prefs.smart_guides = false;
+    s.prefs.snap_to_grid = false;
+    let ids = [[100, 100, 100, 80], [120, 300, 80, 100]]
+        .map(|rect| s.execute("shape.insert", &json!({"preset": "rect", "rect": rect, "text": "Resize test"})).unwrap()["id"].as_u64().unwrap());
+    s.execute("edit.select", &json!({"ids": ids})).unwrap();
+    (s, ids)
+}
+
+/// Simulate file-loaded shapes whose stored boxes have not yet been fitted to their text.
+fn pending_resize_autofit(s: &mut Session, ids: &[u64]) {
+    s.edit(|doc, sel| {
+        let shapes = crate::shapes_mut(doc, sel).unwrap();
+        for id in ids {
+            let sh = deckcraft_model::find_shape_mut(shapes, ShapeId(*id as u32)).unwrap();
+            sh.text.as_mut().unwrap().body.autofit = Some(deckcraft_model::text::AutoFit::Shape);
+        }
+        Ok(())
+    })
+    .unwrap();
+}
+
+/// Resizing multiple selected shapes scales them proportionally around their anchors in one undo step.
+#[test]
+fn resizing_selected_shapes_is_one_undo_step() {
+    let (mut s, [a, b]) = resize_selection_scene();
+    let before = s.doc().unwrap().doc.clone();
+    let steps = s.doc().unwrap().history.undo.len();
+    let down = drag_gesture(&mut s, (200.0, 180.0), (250.0, 210.0));
+    assert_eq!(down["hit"]["kind"], "resize");
+    assert_eq!(down["hit"]["id"], a);
+    for (id, expected) in [(a, [100.0, 100.0, 150.0, 110.0]), (b, [120.0, 300.0, 120.0, 137.5])] {
+        let actual = box_of(&mut s, id);
+        for (key, value) in ["x", "y", "w", "h"].into_iter().zip(expected) {
+            assert_eq!(actual[key], value, "{id}: {key}");
+        }
+    }
+    assert_eq!(s.doc().unwrap().history.undo.len(), steps + 1);
+    let after = s.doc().unwrap().doc.clone();
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(s.doc().unwrap().doc, before, "one undo restores both shapes");
+    s.execute("edit.redo", &json!({})).unwrap();
+    assert_eq!(s.doc().unwrap().doc, after, "one redo resizes both shapes again");
+}
+
+/// Resizing selected shapes refits their text boxes inside the same undo transaction.
+#[test]
+fn resizing_selected_shapes_refits_text_in_the_same_undo_step() {
+    let (mut s, ids) = resize_selection_scene();
+    pending_resize_autofit(&mut s, &ids);
+    let before = s.doc().unwrap().doc.clone();
+    let steps = s.doc().unwrap().history.undo.len();
+    // An east-handle drag changes width only; a height change must come from text fitting.
+    drag_gesture(&mut s, (200.0, 140.0), (250.0, 140.0));
+    for (id, old_height) in ids.into_iter().zip([80.0, 100.0]) {
+        assert_ne!(box_of(&mut s, id)["h"], old_height, "both shapes' text is refitted");
+    }
+    assert_eq!(s.doc().unwrap().history.undo.len(), steps + 1);
+    let after = s.doc().unwrap().doc.clone();
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(s.doc().unwrap().doc, before);
+    s.execute("edit.redo", &json!({})).unwrap();
+    assert_eq!(s.doc().unwrap().doc, after, "redo includes the final text fit");
+}
+
+/// Clicking a resize handle without dragging neither modifies shapes nor triggers text autofit.
+#[test]
+fn clicking_a_resize_handle_does_not_change_or_refit_selected_shapes() {
+    let (mut s, ids) = resize_selection_scene();
+    pending_resize_autofit(&mut s, &ids);
+    let before = s.doc().unwrap().doc.clone();
+    let steps = s.doc().unwrap().history.undo.len();
+    let revision = s.doc().unwrap().revision;
+    for kind in [PointerKind::Down, PointerKind::Up] {
+        s.pointer(PointerEvent { kind, x: 200.0, y: 180.0, tol: 3.0, ..Default::default() }).unwrap();
+    }
+    assert_eq!(s.doc().unwrap().doc, before);
+    assert_eq!(s.doc().unwrap().history.undo.len(), steps, "a click creates no undo entry");
+    assert_eq!(s.doc().unwrap().revision, revision);
+    assert!(std::sync::Arc::ptr_eq(&s.doc().unwrap().doc, &before), "a click does not dirty the document");
+    // Ensure this fixture would catch an accidental refit on release.
+    for id in ids {
+        cmd::text::fit_text_box(&mut s, ShapeId(id as u32)).unwrap();
+    }
+    assert_ne!(s.doc().unwrap().doc, before);
+}
+
+/// Locked shapes in a multi-selection are excluded from both resizing and post-resize text fitting.
+#[test]
+fn resizing_selected_shapes_skips_locked_shapes_and_their_text_fit() {
+    let (mut s, [a, b]) = resize_selection_scene();
+    pending_resize_autofit(&mut s, &[b]);
+    s.execute("shape.lock", &json!({"ids": [b], "locked": true})).unwrap();
+    s.execute("edit.select", &json!({"ids": [a, b]})).unwrap();
+    let locked = s.doc().unwrap().shape(ShapeId(b as u32)).unwrap().clone();
+    let before = s.doc().unwrap().doc.clone();
+    let steps = s.doc().unwrap().history.undo.len();
+    drag_gesture(&mut s, (200.0, 180.0), (250.0, 210.0));
+    assert_eq!(box_of(&mut s, a)["w"], 150.0);
+    assert_eq!(box_of(&mut s, a)["h"], 110.0);
+    assert_eq!(s.doc().unwrap().shape(ShapeId(b as u32)).unwrap(), &locked, "the locked shape is neither resized nor refitted");
+    assert_eq!(s.doc().unwrap().history.undo.len(), steps + 1);
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(s.doc().unwrap().doc, before);
+}
+
+/// Resizing selected shapes excludes other selected resize targets from smart-guide snapping.
+#[test]
+fn resizing_selected_shapes_does_not_snap_to_other_resize_targets() {
+    for reverse in [false, true] {
+        let (mut s, [a, b]) = resize_selection_scene();
+        s.prefs.smart_guides = true;
+        let ids = if reverse { [b, a] } else { [a, b] };
+        s.execute("edit.select", &json!({"ids": ids})).unwrap();
+        // Within snap tolerance of the other selected shape's original right edge.
+        drag_gesture(&mut s, (200.0, 140.0), (203.0, 140.0));
+        assert_eq!(box_of(&mut s, a)["w"], 103.0, "first shape must not snap back");
+        assert_eq!(box_of(&mut s, b)["w"], 82.4, "selection order must not affect snapping");
+    }
+}
+
+/// Resizing selected shapes snaps the active shape against unselected stationary shapes and scales others proportionally.
+#[test]
+fn resizing_selected_shapes_still_snaps_to_stationary_shapes() {
+    let (mut s, [a, b]) = resize_selection_scene();
+    let fixed = s.execute("shape.insert", &json!({"preset": "rect", "rect": [207, 430, 100, 80]})).unwrap()["id"].as_u64().unwrap();
+    let fixed_before = box_of(&mut s, fixed);
+    s.execute("edit.select", &json!({"ids": [a, b]})).unwrap();
+    s.prefs.smart_guides = true;
+    drag_gesture(&mut s, (200.0, 140.0), (203.0, 140.0));
+    assert_eq!(box_of(&mut s, a)["w"], 107.0);
+    assert!((box_of(&mut s, b)["w"].as_f64().unwrap() - 85.6).abs() < 1e-9);
+    assert_eq!(box_of(&mut s, fixed), fixed_before);
+}
+
+/// Secondary pictures resize uniformly around their anchor, preserving independent flips
+/// and keeping the complete multi-selection resize in one undo step.
+#[test]
+fn resizing_selected_shapes_resizes_secondary_pictures() {
+    // Pointer destination, Alt, expected rectangle, expected picture, expected flips.
+    let cases = [
+        ((180.0, 200.0), false, [100.0, 100.0, 80.0, 100.0], [300.0, 300.0, 80.0, 80.0], [false, false]),
+        ((200.0, 180.0), false, [100.0, 100.0, 100.0, 80.0], [300.0, 300.0, 80.0, 80.0], [false, false]),
+        ((220.0, 200.0), false, [100.0, 100.0, 120.0, 100.0], [300.0, 300.0, 120.0, 120.0], [false, false]),
+        ((200.0, 220.0), false, [100.0, 100.0, 100.0, 120.0], [300.0, 300.0, 120.0, 120.0], [false, false]),
+        ((180.0, 200.0), true, [120.0, 100.0, 60.0, 100.0], [320.0, 320.0, 60.0, 60.0], [false, false]),
+        ((200.0, 180.0), true, [100.0, 120.0, 100.0, 60.0], [320.0, 320.0, 60.0, 60.0], [false, false]),
+        ((80.0, 200.0), false, [80.0, 100.0, 20.0, 100.0], [280.0, 300.0, 20.0, 20.0], [true, false]),
+        ((200.0, 80.0), false, [100.0, 80.0, 100.0, 20.0], [300.0, 280.0, 20.0, 20.0], [false, true]),
+    ];
+
+    for (to, alt, expected_rect, expected_picture, flips) in cases {
+        let mut s = session();
+        s.execute("slide.new", &json!({"layout": "blank"})).unwrap();
+        s.prefs.smart_guides = false;
+        s.prefs.snap_to_grid = false;
+
+        let rect = s.execute("shape.insert", &json!({"preset": "rect", "rect": [100, 100, 100, 100]})).unwrap()["id"].as_u64().unwrap();
+        let picture = ramp_picture(&mut s, 1, [300, 300, 100, 100]).as_u64().unwrap();
+        s.execute("edit.select", &json!({"ids": [rect, picture]})).unwrap();
+
+        let before = s.doc().unwrap().doc.clone();
+        let steps = s.doc().unwrap().history.undo.len();
+        let mods = Mods { alt, ..Default::default() };
+        let ev = |kind, (x, y): (f64, f64)| PointerEvent { kind, x, y, mods, tol: 3.0, pressure: None };
+
+        let down = s.pointer(ev(PointerKind::Down, (200.0, 200.0))).unwrap();
+        assert_eq!(down["hit"]["kind"], "resize");
+        assert_eq!(down["hit"]["id"], rect);
+        assert_eq!(down["hit"]["handle"], 4);
+
+        s.pointer(ev(PointerKind::Drag, ((200.0 + to.0) / 2.0, (200.0 + to.1) / 2.0))).unwrap();
+        s.pointer(ev(PointerKind::Drag, to)).unwrap();
+        s.pointer(ev(PointerKind::Up, to)).unwrap();
+
+        for (id, expected) in [(rect, expected_rect), (picture, expected_picture)] {
+            let actual = box_of(&mut s, id);
+            for (key, value) in ["x", "y", "w", "h"].into_iter().zip(expected) {
+                let got = actual[key].as_f64().unwrap();
+                assert!((got - value).abs() < 1e-9, "{to:?}, alt={alt}, shape={id}, {key}: expected {value}, got {got}");
+            }
+
+            let xfrm = s.doc().unwrap().shape(ShapeId(id as u32)).unwrap().xfrm.unwrap();
+            assert_eq!([xfrm.flip_h, xfrm.flip_v], flips, "{to:?}, alt={alt}, shape={id}");
+        }
+
+        assert_eq!(s.doc().unwrap().history.undo.len(), steps + 1);
+        let after = s.doc().unwrap().doc.clone();
+        s.execute("edit.undo", &json!({})).unwrap();
+        assert_eq!(s.doc().unwrap().doc, before);
+        s.execute("edit.redo", &json!({})).unwrap();
+        assert_eq!(s.doc().unwrap().doc, after);
+    }
+}
+
 /// #961: dragging the east handle snaps the dragged (right) edge, even when the fixed left edge
 /// already lines up with another shape. The nearest line used to be the fixed edge's, at distance 0.
 #[test]
diff --git a/crates/engine/src/tools.rs b/crates/engine/src/tools.rs
index 78c6ed35..82f53dfc 100644
--- a/crates/engine/src/tools.rs
+++ b/crates/engine/src/tools.rs
@@ -150,8 +150,10 @@ enum Drag {
     },
     Resize {
         id: ShapeId,
-        handle: u8,
         orig: Xfrm,
+        ids: Vec<ShapeId>,
+        handle: u8,
+        origs: Vec<(ShapeId, Xfrm)>,
         start: Point,
     },
     LineEnd {
diff --git a/crates/engine/src/tools/drag.rs b/crates/engine/src/tools/drag.rs
index 21aac4f3..dcee9cf7 100644
--- a/crates/engine/src/tools/drag.rs
+++ b/crates/engine/src/tools/drag.rs
@@ -13,6 +13,7 @@ struct MoveDrag {
 }
 
 impl Session {
+    /// Update the active drag interaction using the pointer position and modifiers.
     pub(super) fn drag(&mut self, p: Point, mods: Mods, tol: f64) -> Result<Value> {
         let Some(drag) = self.tool.drag.clone() else { return Ok(Value::Null) };
         match drag {
@@ -26,10 +27,48 @@ impl Session {
             Drag::Move { ids, start, origs, moved, duplicate, enter_text } => {
                 return self.drag_move(MoveDrag { ids, start, origs, moved, duplicate, enter_text }, p, mods, tol);
             }
-            Drag::Resize { id, handle, orig, start } => {
-                let nx = resize_box(&orig, handle, p - start, mods.shift || self.is_picture(id), mods.alt);
-                let nx = self.snap_resize(nx, &orig, handle, id, tol);
-                self.set_xfrm(id, nx)?;
+            Drag::Resize { id, orig, ids, handle, origs, start } => {
+                let keep_aspect = mods.shift || self.is_picture(id);
+                let nx = resize_box(&orig, handle, p - start, keep_aspect, mods.alt);
+                let nx = self.snap_resize(nx, handle, &ids, tol);
+                let sx = if orig.w > 1e-9 { (nx.w / orig.w) * if nx.flip_h != orig.flip_h { -1.0 } else { 1.0 } - 1.0 } else { 0.0 };
+                let sy = if orig.h > 1e-9 { (nx.h / orig.h) * if nx.flip_v != orig.flip_v { -1.0 } else { 1.0 } - 1.0 } else { 0.0 };
+                let div = if mods.alt { 2.0 } else { 1.0 };
+                let hx = match handle {
+                    0 | 6 | 7 => -1.0,
+                    2..=4 => 1.0,
+                    _ => 0.0,
+                };
+                let hy = match handle {
+                    0..=2 => -1.0,
+                    4..=6 => 1.0,
+                    _ => 0.0,
+                };
+                for (tid, o) in &origs {
+                    let target_nx = if *tid == id {
+                        nx
+                    } else {
+                        let picture = self.is_picture(*tid);
+                        let (sx, sy) = if picture && matches!(handle, 0 | 2 | 4 | 6) {
+                            // Use the axis with the larger relative change so an unchanged
+                            // dimension cannot cancel shrinking. Preserve each axis's flip.
+                            let scale_x = 1.0 + sx;
+                            let scale_y = 1.0 + sy;
+                            let scale = if sx.abs() >= sy.abs() { scale_x.abs() } else { scale_y.abs() };
+                            (scale.copysign(scale_x) - 1.0, scale.copysign(scale_y) - 1.0)
+                        } else {
+                            (sx, sy)
+                        };
+
+                        let lp = Affine::rotate(o.rot.to_radians())
+                            * Point::new(
+                                hx * sx * o.w / div * if o.flip_h { -1.0 } else { 1.0 },
+                                hy * sy * o.h / div * if o.flip_v { -1.0 } else { 1.0 },
+                            );
+                        resize_box(o, handle, Vec2::new(lp.x, lp.y), picture, mods.alt)
+                    };
+                    self.set_xfrm(*tid, target_nx)?;
+                }
             }
             Drag::LineEnd { id, end, orig } => {
                 let a = orig.affine();
diff --git a/crates/engine/src/tools/geometry.rs b/crates/engine/src/tools/geometry.rs
index 536a4ead..cbbd0127 100644
--- a/crates/engine/src/tools/geometry.rs
+++ b/crates/engine/src/tools/geometry.rs
@@ -228,7 +228,7 @@ impl Session {
     }
 
     /// Snap the edges that resize handle `handle` drags in the resized box `x` to the smart guides.
-    pub(super) fn snap_resize(&mut self, x: Xfrm, _orig: &Xfrm, handle: u8, id: ShapeId, tol: f64) -> Xfrm {
+    pub(super) fn snap_resize(&mut self, x: Xfrm, handle: u8, exclude: &[ShapeId], tol: f64) -> Xfrm {
         if x.rot != 0.0 {
             self.tool.guides.clear();
             return x;
@@ -241,7 +241,7 @@ impl Session {
         let (top, bottom) = (matches!(handle, 0..=2), matches!(handle, 4..=6));
         let (moves_left, moves_right) = if x.flip_h { (right, left) } else { (left, right) };
         let (moves_top, moves_bottom) = if x.flip_v { (bottom, top) } else { (top, bottom) };
-        let (off, guides) = self.snap_edges(r, &[id], tol * 1.5, true, [moves_left, false, moves_right], [moves_top, false, moves_bottom]);
+        let (off, guides) = self.snap_edges(r, exclude, tol * 1.5, true, [moves_left, false, moves_right], [moves_top, false, moves_bottom]);
         let mut nx = x;
         if moves_left {
             nx.x += off.x;
diff --git a/crates/engine/src/tools/pointer.rs b/crates/engine/src/tools/pointer.rs
index cb71cfed..d20ae931 100644
--- a/crates/engine/src/tools/pointer.rs
+++ b/crates/engine/src/tools/pointer.rs
@@ -220,6 +220,7 @@ impl Session {
         }
     }
 
+    /// Handle a pointer press and start the applicable tool interaction.
     fn down(&mut self, p: Point, mods: Mods, tol: f64) -> Result<Value> {
         if let Some(Drag::Freeform { mode, mut points, .. }) = self.tool.drag.clone() {
             // Next click of a freeform: close on the start point, else add a vertex.
@@ -303,8 +304,12 @@ impl Session {
             Some(Hit::TableRow { id, row }) => self.begin_table_border(id, false, row, p)?,
             Some(Hit::Resize { id, handle }) => {
                 let orig = st.shape(id).map(|s| xfrm_of(&st.doc, &st.selection, s)).unwrap_or_default();
+                let ids: Vec<ShapeId> = if st.selection.shapes.contains(&id) { st.selection.shapes.clone() } else { vec![id] };
+                let origs: Vec<(ShapeId, Xfrm)> =
+                    ids.iter().filter_map(|i| st.shape(*i).filter(|s| !s.locked).map(|s| (*i, xfrm_of(&st.doc, &st.selection, s)))).collect();
+                let ids: Vec<ShapeId> = origs.iter().map(|(id, _)| *id).collect();
                 self.begin("Size");
-                self.tool.drag = Some(Drag::Resize { id, handle, orig, start: p });
+                self.tool.drag = Some(Drag::Resize { id, orig, ids, handle, origs, start: p });
             }
             Some(Hit::LineEnd { id, end }) => {
                 let orig = st.shape(id).map(|s| xfrm_of(&st.doc, &st.selection, s)).unwrap_or_default();
@@ -436,6 +441,7 @@ impl Session {
         Ok(json!({"hit": serde_json::to_value(&hit).unwrap_or_default()}))
     }
 
+    /// Handle a pointer release and finalize the active tool interaction.
     fn up(&mut self, p: Point, mods: Mods) -> Result<Value> {
         let drag = self.tool.drag.take();
         self.tool.guides.clear();
@@ -558,10 +564,22 @@ impl Session {
                     out = self.add_ink(points)?;
                 }
             }
-            Some(Drag::Resize { id, .. }) => {
+            Some(Drag::Resize { origs, .. }) => {
+                let changed: Vec<ShapeId> = origs
+                    .iter()
+                    .filter_map(|(id, orig)| {
+                        let current = self.active().and_then(|st| st.shape(*id).map(|s| xfrm_of(&st.doc, &st.selection, s)))?;
+
+                        (current != *orig).then_some(*id)
+                    })
+                    .collect();
+                if !changed.is_empty() {
+                    for id in changed {
+                        let _ = cmd::text::fit_text_box(self, id);
+                        self.refit_after_resize(id)?;
+                    }
+                }
                 self.commit();
-                let _ = cmd::text::fit_text_box(self, id);
-                self.refit_after_resize(id)?;
             }
             Some(Drag::TextSelect { before, .. }) => {
                 out = self.paint_if_selection_changed(before, out)?;