diff --git a/mock/e2e/phy.spec.ts b/mock/e2e/phy.spec.ts
index 51803a8..6a51259 100644
--- a/mock/e2e/phy.spec.ts
+++ b/mock/e2e/phy.spec.ts
@@ -706,3 +706,37 @@ test("キャンバスのviewBoxはツールバーを除いたSVGの大きさに
   expect(Math.abs(w! - box.width)).toBeLessThan(1);
   expect(Math.abs(h! - box.height)).toBeLessThan(1);
 });
+
+test("スイッチ・スタビの十字はトグルで出し、スタビ候補を複数選べる", async ({ page }) => {
+  const key = page.locator('[data-node-type="key"]').first();
+  const id = await key.getAttribute("data-node-id");
+  await expect(page.locator(".mount-layer")).toHaveCount(0);
+  await page.getByRole("button", { name: "スイッチ・スタビライザーの位置" }).click();
+  const mark = page.locator(`[data-mount-id="${id}"]`);
+  await expect(mark.locator(".switch")).toHaveCount(1);
+  await expect(mark.locator(".stab")).toHaveCount(0);
+
+  await key.click();
+  await expect(page.locator(".stabilizers")).toContainText("候補なし");
+  await page.getByLabel("Width").fill("6.25");
+  await page.getByLabel("Width").blur();
+  for (const label of ["±50mm", "±40mm", "±42.5mm"]) await expect(page.getByLabel(label)).not.toBeChecked();
+  await page.getByLabel("±50mm").check();
+  await page.getByLabel("±40mm").check();
+  await expect(mark.locator(".stab")).toHaveCount(4);
+
+  const switchX = async () => (await mark.locator(".switch").boundingBox())!.x;
+  const before = await switchX();
+  await page.getByLabel("switchOffset X").fill("0.625");
+  await page.getByLabel("switchOffset X").blur();
+  await expect.poll(switchX).toBeGreaterThan(before + 10);
+  await expect(mark.locator(".stab")).toHaveCount(4);
+
+  await page.getByRole("button", { name: "Undo" }).click();
+  await page.getByRole("button", { name: "Undo" }).click();
+  await expect(mark.locator(".stab")).toHaveCount(2);
+  await expect(page.getByLabel("±40mm")).not.toBeChecked();
+
+  await page.getByRole("button", { name: "スイッチ・スタビライザーの位置" }).click();
+  await expect(page.locator(".mount-layer")).toHaveCount(0);
+});
diff --git a/mock/src/domain/stabilizers.ts b/mock/src/domain/stabilizers.ts
new file mode 100644
index 0000000..7daefc1
--- /dev/null
+++ b/mock/src/domain/stabilizers.ts
@@ -0,0 +1,73 @@
+import type { Point, Size } from "./phy";
+
+/** One candidate stabilizer layout: two mounts at ±offset along the key's long axis, in U. */
+export type StabilizerCandidate = { id: string; label: string; offset: number };
+
+const MM = 1 / 19.05;
+/** Cherry MX spacings by key length. provisional/decisions.md「単位8のスタビ候補」. */
+const TABLE: { lengths: number[]; candidates: StabilizerCandidate[] }[] = [
+  {
+    lengths: [2, 2.25, 2.5, 2.75],
+    candidates: [{ id: "11.938mm", label: "±11.938mm", offset: 11.938 * MM }],
+  },
+  { lengths: [3], candidates: [{ id: "1u", label: "±1U", offset: 1 }] },
+  { lengths: [4], candidates: [{ id: "1.5u", label: "±1.5U", offset: 1.5 }] },
+  { lengths: [4.5], candidates: [{ id: "34.671mm", label: "±34.671mm", offset: 34.671 * MM }] },
+  { lengths: [5.5], candidates: [{ id: "2.25u", label: "±2.25U", offset: 2.25 }] },
+  {
+    lengths: [6],
+    candidates: [
+      { id: "2.5u", label: "±2.5U", offset: 2.5 },
+      { id: "2u", label: "±2U", offset: 2 },
+    ],
+  },
+  {
+    lengths: [6.25],
+    candidates: [
+      { id: "50mm", label: "±50mm", offset: 50 * MM },
+      { id: "40mm", label: "±40mm", offset: 40 * MM },
+      { id: "42.5mm", label: "±42.5mm", offset: 42.5 * MM },
+    ],
+  },
+  { lengths: [6.5], candidates: [{ id: "2.75u", label: "±2.75U", offset: 2.75 }] },
+  { lengths: [7], candidates: [{ id: "3u", label: "±3U", offset: 3 }] },
+  { lengths: [8, 9, 9.75, 10], candidates: [{ id: "3.5u", label: "±3.5U", offset: 3.5 }] },
+];
+
+const EPS = 1e-9;
+/** Non-rectangular keys (ISO Enter, BAE, stepped) have no candidates yet. */
+function irregular(size: Size): boolean {
+  return [size.x2, size.y2, size.w2, size.h2].some((v) => v !== undefined);
+}
+export function stabilizerCandidates(size: Size): StabilizerCandidate[] {
+  if (irregular(size)) return [];
+  const length = Math.max(size.w, size.h);
+  return TABLE.find((row) => row.lengths.some((l) => Math.abs(l - length) < EPS))?.candidates ?? [];
+}
+/** A size with a single candidate shows it until chosen otherwise; several start unselected. */
+export function defaultStabilizerSelection(size: Size): string[] {
+  const candidates = stabilizerCandidates(size);
+  return candidates.length === 1 ? [candidates[0]!.id] : [];
+}
+/** Mount points in key-local coordinates, around the (w, h) rectangle's center, not the switch. */
+export function stabilizerPoints(size: Size, ids: string[]): Point[] {
+  const cx = size.w / 2,
+    cy = size.h / 2,
+    vertical = size.h > size.w;
+  return stabilizerCandidates(size)
+    .filter((c) => ids.includes(c.id))
+    .flatMap((c) =>
+      vertical
+        ? [
+            { x: cx, y: cy - c.offset },
+            { x: cx, y: cy + c.offset },
+          ]
+        : [
+            { x: cx - c.offset, y: cy },
+            { x: cx + c.offset, y: cy },
+          ],
+    );
+}
+export function switchPoint(key: { size: Size; switchOffset?: Point }): Point {
+  return { x: key.size.w / 2 + (key.switchOffset?.x ?? 0), y: key.size.h / 2 + (key.switchOffset?.y ?? 0) };
+}
diff --git a/mock/src/ui/phy/PhyEditor.vue b/mock/src/ui/phy/PhyEditor.vue
index ce778ba..d34e6e7 100644
--- a/mock/src/ui/phy/PhyEditor.vue
+++ b/mock/src/ui/phy/PhyEditor.vue
@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { nextTick, onMounted, onUnmounted, ref, watch } from "vue";
+import { computed, nextTick, onMounted, onUnmounted, ref, watch } from "vue";
 import type { ProjectFile } from "../../domain/project";
 import type { Node } from "../../domain/phy";
 import type { Dispatch } from "../types";
@@ -12,7 +12,18 @@ import PhyBadgeLayer from "./PhyBadgeLayer.vue";
 import PhyToolbar from "./PhyToolbar.vue";
 import PhyProperties from "./PhyProperties.vue";
 import PhyHoldOverlay from "./PhyHoldOverlay.vue";
-import { normalizeSelection, nextGrid, insertionContainer, structuralNodes, visibleNodeIds } from "./logic";
+import PhyMountLayer from "./PhyMountLayer.vue";
+import {
+  normalizeSelection,
+  nextGrid,
+  insertionContainer,
+  structuralNodes,
+  visibleNodeIds,
+  stabilizerSelections,
+  selectedStabilizers,
+  withStabilizers,
+} from "./logic";
+import { stabilizerCandidates } from "../../domain/stabilizers";
 import { usePhyClipboard } from "./usePhyClipboard";
 import { usePhyViewport } from "./usePhyViewport";
 import { usePhyCanvasPointer } from "./usePhyCanvasPointer";
@@ -296,6 +307,15 @@ function openBadge(g: Node, e: PointerEvent | MouseEvent) {
   const top = r.bottom + 150 < (paneRect?.bottom ?? Infinity) ? r.bottom + 4 : r.top - 150;
   popoverPos.value = overlayPoint(left, top, 210, 150);
 }
+const showMounts = ref(false);
+const stabilizerChoice = computed(() => {
+  const item = prop.value;
+  if (item?.type !== "key") return null;
+  return {
+    candidates: stabilizerCandidates(item.size),
+    selected: selectedStabilizers(stabilizerSelections(props.project), item),
+  };
+});
 function onFocus(_id: string) {
   if (
     pointer.priorSelection().length === 1 &&
@@ -334,6 +354,8 @@ function onFocus(_id: string) {
         @focus="focus = $event"
         :hold-mode="holdMode"
         @hold-mode="holdMode = holdMode === 'loop' ? 'list' : 'loop'"
+        :show-mounts="showMounts"
+        @mounts="showMounts = !showMounts"
       />
       <PhyHoldOverlay
         v-if="hold.open.value"
@@ -394,6 +416,14 @@ function onFocus(_id: string) {
             @down="down"
             @focus="onFocus"
           />
+          <PhyMountLayer
+            v-if="showMounts"
+            :nodes="focus ? [node(focus)!] : project.phy.root"
+            :variants="variants"
+            :selections="stabilizerSelections(project)"
+            :zoom="zoom"
+            :parent="focus ? focusParentMatrix(focus) : undefined"
+          />
           <PhySelectionLayer
             :nodes="focus ? [node(focus)!] : project.phy.root"
             :selected="selected"
@@ -484,6 +514,8 @@ function onFocus(_id: string) {
       @change-variant="chooseVariant"
       @delete-node="(id) => askDelete(id)"
       @add-variant="(groupId, name) => addVariantToGroup(groupId, name)"
+      :stabilizers="stabilizerChoice"
+      @stabilizers="(keyId, ids) => dispatch('スタビ位置', (p) => withStabilizers(p, keyId, ids))"
     />
   </section>
 </template>
diff --git a/mock/src/ui/phy/PhyMountLayer.vue b/mock/src/ui/phy/PhyMountLayer.vue
new file mode 100644
index 0000000..8083a88
--- /dev/null
+++ b/mock/src/ui/phy/PhyMountLayer.vue
@@ -0,0 +1,44 @@
+<script setup lang="ts">
+import { computed } from "vue";
+import type { Node } from "../../domain/phy";
+import type { Affine } from "../../domain/geometry";
+import { mountMarks, type StabilizerSelections } from "./logic";
+const props = withDefaults(
+  defineProps<{
+    nodes: Node[];
+    variants: Record<string, string>;
+    selections: StabilizerSelections;
+    zoom: number;
+    parent?: Affine;
+  }>(),
+  { parent: () => ({ a: 1, b: 0, c: 0, d: 1, e: 0, f: 0 }) },
+);
+const marks = computed(() => mountMarks(props.nodes, props.variants, props.selections, props.parent));
+// 十字の大きさは画面上で固定する。
+const cross = (p: { x: number; y: number }) => {
+  const r = 6 / props.zoom;
+  return `M ${p.x - r} ${p.y} H ${p.x + r} M ${p.x} ${p.y - r} V ${p.y + r}`;
+};
+const affineText = (m: Affine) => `matrix(${m.a} ${m.b} ${m.c} ${m.d} ${m.e} ${m.f})`;
+</script>
+<template>
+  <g class="mount-layer" pointer-events="none">
+    <g v-for="mark in marks" :key="mark.id" :data-mount-id="mark.id" :transform="affineText(mark.transform)">
+      <path class="switch" :d="cross(mark.switchAt)" />
+      <path v-for="(p, i) in mark.stabs" :key="i" class="stab" :d="cross(p)" />
+    </g>
+  </g>
+</template>
+<style scoped>
+path {
+  fill: none;
+  stroke-width: 2px;
+  vector-effect: non-scaling-stroke;
+}
+.switch {
+  stroke: #c2185b;
+}
+.stab {
+  stroke: #00897b;
+}
+</style>
diff --git a/mock/src/ui/phy/PhyProperties.vue b/mock/src/ui/phy/PhyProperties.vue
index fadf553..4827c24 100644
--- a/mock/src/ui/phy/PhyProperties.vue
+++ b/mock/src/ui/phy/PhyProperties.vue
@@ -1,11 +1,13 @@
 <script setup lang="ts">
 import { computed, ref } from "vue";
 import type { Node, Transform } from "../../domain/phy";
+import type { StabilizerCandidate } from "../../domain/stabilizers";
 const props = defineProps<{
   selectedCount: number;
   selectedId: string | null;
   item: Node | null;
   mismatch: boolean;
+  stabilizers: { candidates: StabilizerCandidate[]; selected: string[] } | null;
 }>();
 const emit = defineEmits<{
   update: [id: string, change: (node: Node) => void, label?: string];
@@ -14,7 +16,24 @@ const emit = defineEmits<{
   changeVariant: [group: Node, variantId: string];
   deleteNode: [id: string];
   addVariant: [groupId: string, name: string];
+  stabilizers: [keyId: string, ids: string[]];
 }>();
+function setSwitchOffset(axis: "x" | "y", value: number) {
+  emit("update", props.item!.id, (n) => {
+    if (n.type !== "key") return;
+    const offset = { x: n.switchOffset?.x ?? 0, y: n.switchOffset?.y ?? 0, [axis]: value };
+    if (offset.x === 0 && offset.y === 0) delete n.switchOffset;
+    else n.switchOffset = offset;
+  });
+}
+function toggleStabilizer(id: string, on: boolean) {
+  const current = props.stabilizers?.selected ?? [];
+  emit(
+    "stabilizers",
+    props.item!.id,
+    on ? [...current.filter((x) => x !== id), id] : current.filter((x) => x !== id),
+  );
+}
 const group = computed(() => (props.item?.type === "variantGroup" ? props.item : null));
 const frameX = ref(0);
 const frameY = ref(0);
@@ -94,6 +113,33 @@ const frameR = ref(0);
                 })
               "
           /></label>
+          <label
+            >switchOffset X
+            <input
+              type="number"
+              step="any"
+              :value="item.switchOffset?.x ?? 0"
+              @change="setSwitchOffset('x', Number(($event.target as HTMLInputElement).value))"
+          /></label>
+          <label
+            >switchOffset Y
+            <input
+              type="number"
+              step="any"
+              :value="item.switchOffset?.y ?? 0"
+              @change="setSwitchOffset('y', Number(($event.target as HTMLInputElement).value))"
+          /></label>
+          <div class="stabilizers">
+            スタビ
+            <span v-if="!stabilizers?.candidates.length" class="none">候補なし</span>
+            <label v-for="c in stabilizers?.candidates ?? []" :key="c.id" class="check"
+              ><input
+                type="checkbox"
+                :checked="stabilizers!.selected.includes(c.id)"
+                @change="toggleStabilizer(c.id, ($event.target as HTMLInputElement).checked)"
+              />{{ c.label }}</label
+            >
+          </div>
           <label
             >Label
             <input
@@ -174,4 +220,15 @@ const frameR = ref(0);
   width: 110px;
   margin-left: auto;
 }
+.properties label.check {
+  margin: 4px 0 4px 12px;
+}
+.properties label.check input {
+  width: auto;
+  margin-left: 0;
+}
+.stabilizers .none {
+  margin-left: 8px;
+  color: #6b7380;
+}
 </style>
diff --git a/mock/src/ui/phy/PhyToolbar.vue b/mock/src/ui/phy/PhyToolbar.vue
index 09754aa..0537a6d 100644
--- a/mock/src/ui/phy/PhyToolbar.vue
+++ b/mock/src/ui/phy/PhyToolbar.vue
@@ -7,6 +7,7 @@ defineProps<{
   focus: string | null;
   crumbs: { id: string | null; label: string }[];
   holdMode: "loop" | "list";
+  showMounts: boolean;
 }>();
 const emit = defineEmits<{
   keyAdd: [];
@@ -25,6 +26,7 @@ const emit = defineEmits<{
   help: [];
   focus: [id: string | null];
   holdMode: [];
+  mounts: [];
 }>();
 function addPart(e: Event) {
   const select = e.target as HTMLSelectElement;
@@ -103,6 +105,15 @@ function addPart(e: Event) {
     >
       {{ holdMode === "loop" ? "⟳" : "☰" }}
     </button>
+    <button
+      title="スイッチ・スタビライザーの位置"
+      aria-label="スイッチ・スタビライザーの位置"
+      :aria-pressed="showMounts"
+      :class="{ on: showMounts }"
+      @click="emit('mounts')"
+    >
+      ✛
+    </button>
     <button title="ショートカット一覧" aria-label="ショートカット一覧" @click="emit('help')">?</button>
     <span v-if="focus">
       <template v-for="(crumb, i) in crumbs" :key="i">
@@ -123,6 +134,10 @@ function addPart(e: Event) {
 .tools select {
   font-size: 12px;
 }
+.tools button.on {
+  background: #dbe8fb;
+  border-color: #1769d2;
+}
 /* 候補の名前でセレクトの幅が変わると、ツールバーが折り返してキャンバスの大きさが変わる */
 .tools select.move-to {
   width: 6em;
diff --git a/mock/src/ui/phy/logic.ts b/mock/src/ui/phy/logic.ts
index 6a1840a..13033a3 100644
--- a/mock/src/ui/phy/logic.ts
+++ b/mock/src/ui/phy/logic.ts
@@ -1,4 +1,11 @@
-import type { Node, PhyFile, Transform } from "../../domain/phy";
+import type { KeyNode, Node, PhyFile, Transform } from "../../domain/phy";
+import type { ProjectFile } from "../../domain/project";
+import {
+  defaultStabilizerSelection,
+  stabilizerCandidates,
+  stabilizerPoints,
+  switchPoint,
+} from "../../domain/stabilizers";
 import { apply, compose, inverse, matrix, type Affine } from "../../domain/geometry";
 
 export function normalizeSelection(file: PhyFile, ids: string[]): string[] {
@@ -324,3 +331,59 @@ export function pasteLocalTransform(sourceWorld: Affine, parentWorld: Affine, st
   const local = compose(inverse(parentWorld), sourceWorld);
   return { x: local.e + step, y: local.f + step, rotation: (Math.atan2(local.b, local.a) * 180) / Math.PI };
 }
+/** スタビ位置の選択は仕様の層に入れず、ProjectFile.ui.phy.stabilizers にキーIDごとに持つ。T-10/T-30。 */
+export type StabilizerSelections = Record<string, string[]>;
+export function stabilizerSelections(project: ProjectFile): StabilizerSelections {
+  const ui = project.ui as { phy?: { stabilizers?: StabilizerSelections } } | undefined;
+  return ui?.phy?.stabilizers ?? {};
+}
+/** 記録がなければサイズの既定。サイズが変わって候補にない記録は捨てて読む。 */
+export function selectedStabilizers(selections: StabilizerSelections, key: KeyNode): string[] {
+  const ids = selections[key.id];
+  if (!ids) return defaultStabilizerSelection(key.size);
+  const known = new Set(stabilizerCandidates(key.size).map((c) => c.id));
+  return ids.filter((id) => known.has(id));
+}
+export function withStabilizers(project: ProjectFile, keyId: string, ids: string[]): ProjectFile {
+  const ui = (project.ui ?? {}) as Record<string, unknown>,
+    phy = (ui.phy ?? {}) as Record<string, unknown>;
+  return {
+    ...project,
+    ui: { ...ui, phy: { ...phy, stabilizers: { ...stabilizerSelections(project), [keyId]: ids } } },
+  };
+}
+export type MountMark = {
+  id: string;
+  transform: Affine;
+  switchAt: { x: number; y: number };
+  stabs: { x: number; y: number }[];
+};
+/** 表示中のキーごとに、スイッチ位置とスタビ位置をキーのローカル座標で返す。 */
+export function mountMarks(
+  roots: Node[],
+  variants: Record<string, string>,
+  selections: StabilizerSelections,
+  parent: Affine = { a: 1, b: 0, c: 0, d: 1, e: 0, f: 0 },
+): MountMark[] {
+  const marks: MountMark[] = [];
+  const visit = (nodes: Node[], ancestor: Affine) => {
+    for (const node of nodes) {
+      const transform = compose(ancestor, matrix(node.transform));
+      if (node.type === "key") {
+        if (node.decal) continue;
+        marks.push({
+          id: node.id,
+          transform,
+          switchAt: switchPoint(node),
+          stabs: stabilizerPoints(node.size, selectedStabilizers(selections, node)),
+        });
+      } else if (node.type === "cluster") visit(node.children, transform);
+      else if (node.type === "variantGroup") {
+        const variant = node.children.find((item) => item.id === (variants[node.id] ?? node.default));
+        if (variant) visit(variant.children, transform);
+      }
+    }
+  };
+  visit(roots, parent);
+  return marks;
+}
diff --git a/mock/tests/stabilizers.test.ts b/mock/tests/stabilizers.test.ts
new file mode 100644
index 0000000..6483f1a
--- /dev/null
+++ b/mock/tests/stabilizers.test.ts
@@ -0,0 +1,95 @@
+import { describe, expect, it } from "vitest";
+import {
+  defaultStabilizerSelection,
+  stabilizerCandidates,
+  stabilizerPoints,
+  switchPoint,
+} from "../src/domain/stabilizers";
+import { mountMarks, selectedStabilizers, stabilizerSelections, withStabilizers } from "../src/ui/phy/logic";
+import type { KeyNode } from "../src/domain/phy";
+import type { ProjectFile } from "../src/domain/project";
+
+const key = (id: string, w: number, h = 1, extra: Partial<KeyNode> = {}): KeyNode => ({
+  type: "key",
+  id,
+  profile: "p",
+  transform: { x: 0, y: 0, rotation: 0 },
+  size: { w, h },
+  ...extra,
+});
+const ids = (w: number, h = 1) => stabilizerCandidates({ w, h }).map((c) => c.id);
+
+describe("stabilizer candidates", () => {
+  it("looks up candidates by the long side", () => {
+    expect(ids(1)).toEqual([]);
+    expect(ids(1.75)).toEqual([]);
+    expect(ids(2.25)).toEqual(["11.938mm"]);
+    expect(ids(1, 2)).toEqual(["11.938mm"]);
+    expect(ids(6)).toEqual(["2.5u", "2u"]);
+    expect(ids(6.25)).toEqual(["50mm", "40mm", "42.5mm"]);
+    expect(ids(10)).toEqual(["3.5u"]);
+    expect(ids(6.75)).toEqual([]);
+  });
+  it("gives no candidates to non-rectangular keys", () => {
+    expect(stabilizerCandidates({ w: 1.25, h: 2, w2: 1.5, h2: 1, x2: -0.25 })).toEqual([]);
+    expect(stabilizerCandidates({ w: 2, h: 1, w2: 2.25 })).toEqual([]);
+  });
+  it("selects a lone candidate by default and nothing when there are several", () => {
+    expect(defaultStabilizerSelection({ w: 2, h: 1 })).toEqual(["11.938mm"]);
+    expect(defaultStabilizerSelection({ w: 6.25, h: 1 })).toEqual([]);
+  });
+  it("places mounts around the rectangle center along the long axis", () => {
+    expect(stabilizerPoints({ w: 7, h: 1 }, ["3u"])).toEqual([
+      { x: 0.5, y: 0.5 },
+      { x: 6.5, y: 0.5 },
+    ]);
+    const [top, bottom] = stabilizerPoints({ w: 1, h: 2 }, ["11.938mm"]);
+    expect(top!.x).toBe(0.5);
+    expect(bottom!.y - top!.y).toBeCloseTo(23.876 / 19.05, 12);
+    expect(stabilizerPoints({ w: 6, h: 1 }, ["2.5u", "2u"])).toHaveLength(4);
+  });
+  it("keeps stabilizers on the key center when the switch is offset", () => {
+    const k = key("k", 6, 1, { switchOffset: { x: 0.5, y: 0 } });
+    expect(switchPoint(k)).toEqual({ x: 3.5, y: 0.5 });
+    expect(stabilizerPoints(k.size, ["2.5u"]).map((p) => p.x)).toEqual([0.5, 5.5]);
+  });
+});
+
+describe("stabilizer selections in ProjectFile.ui", () => {
+  const project = { ui: { other: 1 } } as unknown as ProjectFile;
+  it("falls back to the size default and drops ids the size no longer offers", () => {
+    expect(selectedStabilizers({}, key("a", 2))).toEqual(["11.938mm"]);
+    expect(selectedStabilizers({ a: [] }, key("a", 2))).toEqual([]);
+    expect(selectedStabilizers({ a: ["2.5u", "3u"] }, key("a", 6))).toEqual(["2.5u"]);
+  });
+  it("writes per key without touching other ui state", () => {
+    const next = withStabilizers(withStabilizers(project, "a", ["50mm"]), "b", []);
+    expect(stabilizerSelections(next)).toEqual({ a: ["50mm"], b: [] });
+    expect((next.ui as { other: number }).other).toBe(1);
+    expect(stabilizerSelections(project)).toEqual({});
+  });
+  it("lists marks for visible keys only, skipping decals", () => {
+    const marks = mountMarks(
+      [
+        key("a", 2),
+        key("d", 2, 1, { decal: true }),
+        {
+          type: "variantGroup",
+          id: "g",
+          name: "g",
+          default: "v1",
+          transform: { x: 0, y: 1, rotation: 0 },
+          children: [
+            { type: "variant", id: "v1", name: "1", children: [key("b", 1)] },
+            { type: "variant", id: "v2", name: "2", children: [key("c", 1)] },
+          ],
+        },
+      ],
+      { g: "v2" },
+      {},
+    );
+    expect(marks.map((m) => m.id)).toEqual(["a", "c"]);
+    expect(marks[1]!.transform.f).toBe(1);
+    expect(marks[0]!.stabs).toHaveLength(2);
+  });
+});