diff --git a/web/src/components/ui/aceternity/floating-dock.tsx b/web/src/components/ui/aceternity/floating-dock.tsx
index 6f02f0f4a..9ab339528 100644
--- a/web/src/components/ui/aceternity/floating-dock.tsx
+++ b/web/src/components/ui/aceternity/floating-dock.tsx
@@ -65,6 +65,13 @@ const DOCK_METRICS: Record<NonNullable<FloatingDockProps["size"]>, DockMetrics>
     compact: { base: 26, magnified: 32, icon: 13, iconMagnified: 16, distance: 84 },
 };
 
+// `window` 存在不代表 `matchMedia` 存在：测试与 renderToString 下它可能是 undefined，
+// 渲染期直接取用会抛 TypeError。指针能力是纯增强，取不到就按"非触屏"处理。
+function coarsePointerQuery(): MediaQueryList | undefined {
+    if (typeof window === "undefined" || typeof window.matchMedia !== "function") return undefined;
+    return window.matchMedia("(pointer: coarse)");
+}
+
 const TOUCH_DOCK_METRICS: Record<NonNullable<FloatingDockProps["size"]>, DockMetrics> = {
     default: { base: 40, magnified: 40, icon: 18, iconMagnified: 18, distance: 0 },
     compact: { base: 36, magnified: 36, icon: 16, iconMagnified: 16, distance: 0 },
@@ -73,12 +80,13 @@ const TOUCH_DOCK_METRICS: Record<NonNullable<FloatingDockProps["size"]>, DockMet
 export const FloatingDock = forwardRef<HTMLDivElement, FloatingDockProps>(function FloatingDock({ items, size = "default", embedded = false, className, style, ariaLabel = "画布工具", showLabels = false }, forwardedRef) {
     const mouseX = useMotionValue(Number.POSITIVE_INFINITY);
     const reducedMotion = useReducedMotion();
-    const [coarsePointer, setCoarsePointer] = useState(() => typeof window !== "undefined" && window.matchMedia("(pointer: coarse)").matches);
+    const [coarsePointer, setCoarsePointer] = useState(() => coarsePointerQuery()?.matches ?? false);
     // 窄屏下 dock 按钮总宽易超出可用宽度：此时允许横向滚动并禁用放大（放大依赖 overflow-visible，与滚动互斥）
     const [narrow, setNarrow] = useState(() => (typeof window !== "undefined" ? window.innerWidth < 768 : false));
 
     useEffect(() => {
-        const media = window.matchMedia("(pointer: coarse)");
+        const media = coarsePointerQuery();
+        if (!media) return;
         const update = () => setCoarsePointer(media.matches);
         update();
         media.addEventListener("change", update);
diff --git a/web/test/floating-dock-pointer-guard.test.tsx b/web/test/floating-dock-pointer-guard.test.tsx
new file mode 100644
index 000000000..6723bf97f
--- /dev/null
+++ b/web/test/floating-dock-pointer-guard.test.tsx
@@ -0,0 +1,18 @@
+import { describe, expect, test } from "bun:test";
+import { readFileSync } from "node:fs";
+
+// 指针能力探测是纯增强：`window` 存在不代表 `matchMedia` 存在（SSR 垫片、嵌入式 webview、
+// 部分 DOM polyfill 下它是 undefined），而 FloatingDock 在**渲染期**就取
+// `window.matchMedia("(pointer: coarse)")`，取不到会直接抛 TypeError 让整个 dock 渲染失败。
+// 仓库里同一模式已有先例：canvas-workspace-tool-panel.tsx 用 `typeof window.matchMedia === "function"` 守卫。
+describe("floating dock pointer capability probe", () => {
+    const source = readFileSync(new URL("../src/components/ui/aceternity/floating-dock.tsx", import.meta.url), "utf8");
+
+    test("probes matchMedia through a guarded helper", () => {
+        expect(source).toContain('typeof window.matchMedia !== "function"');
+        expect(source).toContain("function coarsePointerQuery()");
+        // 不允许再出现"直接取用 matchMedia 结果"的写法（初始化与 useEffect 都不得裸取）
+        expect(source).not.toMatch(/window\.matchMedia\("\(pointer: coarse\)"\)\.matches/);
+        expect(source).not.toMatch(/const media = window\.matchMedia/);
+    });
+});