diff --git a/src/app/_components/core/bottom-sheet.tsx b/src/app/_components/core/bottom-sheet.tsx
index 813e6d05..2c6e029f 100644
--- a/src/app/_components/core/bottom-sheet.tsx
+++ b/src/app/_components/core/bottom-sheet.tsx
@@ -11,9 +11,9 @@
  *   - 简单 slide-up 动画（与原 Dart 行为接近）
  *   - 调用方只关心内容布局
  */
-import { type ReactNode, useEffect } from "react";
-import { createPortal } from "react-dom";
+import { type ReactNode } from "react";
 
+import { ModalPortal } from "./modal-portal";
 import styles from "./bottom-sheet.module.css";
 
 export interface BottomSheetProps {
@@ -36,40 +36,17 @@ export function BottomSheet({
   persistent = false,
   ariaLabel,
 }: BottomSheetProps) {
-  useEffect(() => {
-    if (!open || typeof document === "undefined") return;
-    const onKey = (e: KeyboardEvent) => {
-      if (e.key === "Escape" && !persistent) onClose();
-    };
-    document.addEventListener("keydown", onKey);
-    const prevOverflow = document.body.style.overflow;
-    document.body.style.overflow = "hidden";
-    return () => {
-      document.removeEventListener("keydown", onKey);
-      document.body.style.overflow = prevOverflow;
-    };
-  }, [open, onClose, persistent]);
-
-  if (!open || typeof document === "undefined") return null;
-
-  return createPortal(
-    <div
-      className={styles.scrim}
-      style={{ background: `rgba(0, 0, 0, ${scrimOpacity})` }}
-      onClick={(e) => {
-        if (!persistent && e.target === e.currentTarget) onClose();
-      }}
+  return (
+    <ModalPortal
+      open={open}
+      onClose={onClose}
+      scrimClassName={styles.scrim}
+      panelClassName={styles.panel}
+      scrimOpacity={scrimOpacity}
+      persistent={persistent}
+      ariaLabel={ariaLabel}
     >
-      <div
-        role="dialog"
-        aria-modal="true"
-        aria-label={ariaLabel}
-        className={styles.panel}
-        onClick={(e) => e.stopPropagation()}
-      >
-        {children}
-      </div>
-    </div>,
-    document.body,
+      {children}
+    </ModalPortal>
   );
 }
diff --git a/src/app/_components/core/dialog.tsx b/src/app/_components/core/dialog.tsx
index e6db488b..eeb4c6e3 100644
--- a/src/app/_components/core/dialog.tsx
+++ b/src/app/_components/core/dialog.tsx
@@ -11,9 +11,9 @@
  *
  * 注意：项目不引入 Radix/shadcn，纯依赖 React + CSS Modules。
  */
-import { type ReactNode, useEffect } from "react";
-import { createPortal } from "react-dom";
+import { type ReactNode } from "react";
 
+import { ModalPortal } from "./modal-portal";
 import styles from "./dialog.module.css";
 
 export interface DialogProps {
@@ -39,41 +39,18 @@ export function Dialog({
   persistent = false,
   ariaLabel,
 }: DialogProps) {
-  useEffect(() => {
-    if (!open || typeof document === "undefined") return;
-    const onKey = (e: KeyboardEvent) => {
-      if (e.key === "Escape" && !persistent) onClose();
-    };
-    document.addEventListener("keydown", onKey);
-    const prevOverflow = document.body.style.overflow;
-    document.body.style.overflow = "hidden";
-    return () => {
-      document.removeEventListener("keydown", onKey);
-      document.body.style.overflow = prevOverflow;
-    };
-  }, [open, onClose, persistent]);
-
-  if (!open || typeof document === "undefined") return null;
-
-  return createPortal(
-    <div
-      className={styles.scrim}
-      style={{ background: `rgba(0, 0, 0, ${scrimOpacity})` }}
-      onClick={(e) => {
-        if (!persistent && e.target === e.currentTarget) onClose();
-      }}
+  return (
+    <ModalPortal
+      open={open}
+      onClose={onClose}
+      scrimClassName={styles.scrim}
+      panelClassName={styles.panel}
+      panelStyle={{ maxWidth }}
+      scrimOpacity={scrimOpacity}
+      persistent={persistent}
+      ariaLabel={ariaLabel}
     >
-      <div
-        role="dialog"
-        aria-modal="true"
-        aria-label={ariaLabel}
-        className={styles.panel}
-        style={{ maxWidth }}
-        onClick={(e) => e.stopPropagation()}
-      >
-        {children}
-      </div>
-    </div>,
-    document.body,
+      {children}
+    </ModalPortal>
   );
 }
diff --git a/src/app/_components/core/modal-portal.tsx b/src/app/_components/core/modal-portal.tsx
new file mode 100644
index 00000000..f4fd20d6
--- /dev/null
+++ b/src/app/_components/core/modal-portal.tsx
@@ -0,0 +1,98 @@
+"use client";
+
+import {
+  type CSSProperties,
+  type MouseEvent,
+  type ReactNode,
+  useEffect,
+} from "react";
+import { createPortal } from "react-dom";
+
+let bodyScrollLockDepth = 0;
+let previousBodyOverflow = "";
+
+export interface ModalPortalProps {
+  open: boolean;
+  onClose: () => void;
+  children: ReactNode;
+  scrimClassName: string;
+  panelClassName: string;
+  scrimOpacity: number;
+  panelStyle?: CSSProperties;
+  persistent?: boolean;
+  ariaLabel?: string;
+}
+
+export function ModalPortal({
+  open,
+  onClose,
+  children,
+  scrimClassName,
+  panelClassName,
+  scrimOpacity,
+  panelStyle,
+  persistent = false,
+  ariaLabel,
+}: ModalPortalProps) {
+  useEffect(() => {
+    if (!open || typeof document === "undefined") return;
+
+    const onKey = (event: KeyboardEvent) => {
+      if (event.key === "Escape" && !persistent) onClose();
+    };
+
+    document.addEventListener("keydown", onKey);
+    lockBodyScroll();
+
+    return () => {
+      document.removeEventListener("keydown", onKey);
+      unlockBodyScroll();
+    };
+  }, [open, onClose, persistent]);
+
+  if (!open || typeof document === "undefined") return null;
+
+  const handleScrimClick = (event: MouseEvent<HTMLDivElement>) => {
+    if (!persistent && event.target === event.currentTarget) onClose();
+  };
+
+  return createPortal(
+    <div
+      className={scrimClassName}
+      style={{ background: `rgba(0, 0, 0, ${scrimOpacity})` }}
+      onClick={handleScrimClick}
+    >
+      <div
+        role="dialog"
+        aria-modal="true"
+        aria-label={ariaLabel}
+        className={panelClassName}
+        style={panelStyle}
+        onClick={(event) => event.stopPropagation()}
+      >
+        {children}
+      </div>
+    </div>,
+    document.body,
+  );
+}
+
+function lockBodyScroll(): void {
+  if (typeof document === "undefined") return;
+
+  if (bodyScrollLockDepth === 0) {
+    previousBodyOverflow = document.body.style.overflow;
+    document.body.style.overflow = "hidden";
+  }
+  bodyScrollLockDepth += 1;
+}
+
+function unlockBodyScroll(): void {
+  if (typeof document === "undefined") return;
+
+  bodyScrollLockDepth = Math.max(0, bodyScrollLockDepth - 1);
+  if (bodyScrollLockDepth === 0) {
+    document.body.style.overflow = previousBodyOverflow;
+    previousBodyOverflow = "";
+  }
+}