diff --git a/src/api/BaseApi.ts b/src/api/BaseApi.ts
index 5d4b084..83082dd 100644
--- a/src/api/BaseApi.ts
+++ b/src/api/BaseApi.ts
@@ -249,6 +249,35 @@ class Base extends Abstract {
         return this.postRequest({ url });
     }
 
+    // ===== 用户外观偏好（外观偏好服务端化 2026-10-08；后端契约见 AppearanceController）=====
+
+    /**
+     * 读当前用户外观偏好聚合：{myTheme, schTheme, avatarMy, avatarSch, logoUrl}（紧凑编码/绝对 URL，查不到为 null）。
+     * 各子应用 yh-theme-init 异步补齐段的同源数据源；选择端预留（本轮设置页双写用不到）。
+     */
+    getAppearance() {
+        const url = path + "/appearance";
+        return this.getRequest<{
+            myTheme: string | null;
+            schTheme: string | null;
+            avatarMy: string | null;
+            avatarSch: string | null;
+            logoUrl: string | null;
+        }>({ url });
+    }
+
+    /** 保存用户自选主题档（紧凑编码 theme|sideDeep01|gradOn01|sideFollow01）；null=跟随学校默认。设置页 fire-and-forget 双写：成功不提示、失败不回滚本地 */
+    saveMyTheme(themeState: string | null) {
+        const url = path + "/saveMyTheme";
+        return this.postRequest({ url, data: { themeState } as any });
+    }
+
+    /** 保存用户自选头像样式（"text"|"silhouette"）；null=跟随学校默认。双写语义同 saveMyTheme */
+    saveMyAvatarStyle(avatarStyle: string | null) {
+        const url = path + "/saveMyAvatarStyle";
+        return this.postRequest({ url, data: { avatarStyle } as any });
+    }
+
     savUserRole(info: any) {
         const url = path + "/user/savUserRole";
         return this.postRequest({ url, data: info as any });
diff --git a/src/components/UserAvatar.vue b/src/components/UserAvatar.vue
index aefb0b1..bd6c318 100644
--- a/src/components/UserAvatar.vue
+++ b/src/components/UserAvatar.vue
@@ -4,7 +4,7 @@
    取值链/取字契约见《设置页修复与默认头像落地方案》§10.1/§10.2；样式全在本文件 <style scoped>（唯一 CSS 源，
    不进通道 icons.src.css——通道 CSS 对 UserHome 不可达，内联分发才能消双份漂移，见同方案 §10.4）。
    根元素即 .yh-avatar 圆：尺寸内联必须挂圆本身（挂外层 span 会被 flex 拉成椭圆，§12 踩坑）。 */
-import { computed } from "vue";
+import { computed, onBeforeUnmount, onMounted, ref } from "vue";
 import { pickAvatarText, resolveAvatarStyle } from "@/utils/avatar";
 
 const props = withDefaults(
@@ -22,7 +22,16 @@ const props = withDefaults(
 );
 
 const text = computed(() => (props.src ? "" : pickAvatarText(props.name)));
-const style = computed(() => resolveAvatarStyle());
+/* 外观偏好异步补齐（yh-theme-init 在挂载后拉服务端真源收敛 localStorage 键）会在
+   document 上派发 yh-appearance-updated；tick 自增让 style 依赖失效重读键，三态即时切换（无需刷新）。 */
+const appearanceTick = ref(0);
+const onAppearanceUpdated = () => { appearanceTick.value += 1; };
+onMounted(() => document.addEventListener("yh-appearance-updated", onAppearanceUpdated));
+onBeforeUnmount(() => document.removeEventListener("yh-appearance-updated", onAppearanceUpdated));
+const style = computed(() => {
+    appearanceTick.value;
+    return resolveAvatarStyle();
+});
 /** 首字态 = style==="text" 且能取到字（契约 §10.2：二者缺一即剪影，取到字但档位是剪影时绝不能出字） */
 const showText = computed(() => style.value === "text" && !!text.value);
 
diff --git a/src/utils/theme.ts b/src/utils/theme.ts
index 8e83c37..6ce0f81 100644
--- a/src/utils/theme.ts
+++ b/src/utils/theme.ts
@@ -1,5 +1,5 @@
 /**
- * 本文件由 YschTheme scripts/gen-theme.mjs 从 assets-src/pc/theme-core.js 生成（版本 20261006-2013-75c1d10），勿手改。
+ * 本文件由 YschTheme scripts/gen-theme.mjs 从 assets-src/pc/theme-core.js 生成（版本 20261008-1831-d9db725），勿手改。
  * 分发方式：YschTheme `npm run sync` 拷进各端 src/utils/theme.ts（与 ThemeSwitcher.vue 配套，MD5 对齐报告）。
  * 运行时档位类名由 /static/js/yh-theme-init.js 在 <head> 内先行挂好，本模块只负责读写与切换。
  */
diff --git a/src/views/Settings.vue b/src/views/Settings.vue
index ad220b7..9aa68bd 100644
--- a/src/views/Settings.vue
+++ b/src/views/Settings.vue
@@ -1033,6 +1033,18 @@ function keyExists(key: string) {
     }
 }
 
+/** ThemeState → 服务端紧凑编码 theme|sideDeep01|gradOn01|sideFollow01（与 SchSettings 存储形态同款） */
+function themeToCompact(s: ThemeState): string {
+    return `${s.theme}|${s.sideDeep ? 1 : 0}|${s.gradOn ? 1 : 0}|${s.sideFollow ? 1 : 0}`;
+}
+/** 外观偏好服务端双写（2026-10-08）：本地体验不变，fire-and-forget 补写真源——成功不提示、失败 console.warn 不回滚本地 */
+function syncMyThemeRemote(s: ThemeState | null) {
+    BaseApi.saveMyTheme(s ? themeToCompact(s) : null).catch((e: any) => console.warn("[appearance] saveMyTheme 失败(本地已生效,不回滚):", e));
+}
+function syncMyAvatarRemote(style: string | null) {
+    BaseApi.saveMyAvatarStyle(style).catch((e: any) => console.warn("[appearance] saveMyAvatarStyle 失败(本地已生效,不回滚):", e));
+}
+
 // ---- 我的主题（所有人）----
 const myCandidate = ref<string>(resolveEffectiveThemeState().theme);
 const myOrigin = computed<"mine" | "school" | "system">(() => {
@@ -1052,17 +1064,20 @@ const myEffective = computed(() => {
 
 function pickMyTheme(key: string) {
     const cur = resolveEffectiveThemeState();
-    saveThemeState({ ...cur, theme: key } as ThemeState);
+    const state = { ...cur, theme: key } as ThemeState;
+    saveThemeState(state);
+    syncMyThemeRemote(state);
     myCandidate.value = key;
     myTick.value += 1;
 }
-/** 跟随学校默认 = 删用户自选键（之后回落学校档/系统默认，§3.3） */
+/** 跟随学校默认 = 删用户自选键（之后回落学校档/系统默认，§3.3）；服务端同步置 NULL */
 function followSchoolTheme() {
     try {
         localStorage.removeItem(THEME_STORAGE_KEY);
     } catch (e) {
         /* 隐私模式静默 */
     }
+    syncMyThemeRemote(null);
     myTick.value += 1;
 }
 
@@ -1170,16 +1185,18 @@ const myAvatarOriginLabel = computed(
     () => ({ mine: "我的选择", school: "学校默认", system: "系统默认" })[myAvatarOrigin.value]
 );
 
-/** 选样式即写键即生效（saveAvatarStyle 直写 localStorage 无响应式，靠 tick 刷示例与来源标签） */
+/** 选样式即写键即生效（saveAvatarStyle 直写 localStorage 无响应式，靠 tick 刷示例与来源标签）；服务端双写真源 */
 function pickMyAvatarStyle(key: AvatarStyle) {
     saveAvatarStyle(key);
+    syncMyAvatarRemote(key);
     myAvatarCandidate.value = key;
     myAvatarTick.value += 1;
 }
 
-/** 跟随学校默认 = 删用户自选键（之后回落学校默认/系统默认，与 followSchoolTheme 同构） */
+/** 跟随学校默认 = 删用户自选键（之后回落学校默认/系统默认，与 followSchoolTheme 同构）；服务端同步置 NULL */
 function followSchoolAvatar() {
     clearAvatarStyle();
+    syncMyAvatarRemote(null);
     myAvatarTick.value += 1;
 }
 
@@ -1255,7 +1272,9 @@ const sideDeep = ref(resolveEffectiveThemeState().sideDeep);
 const gradOn = ref(resolveEffectiveThemeState().gradOn);
 
 function pickSide(patch: Partial<ThemeState>) {
-    saveThemeState({ ...resolveEffectiveThemeState(), ...patch } as ThemeState);
+    const state = { ...resolveEffectiveThemeState(), ...patch } as ThemeState;
+    saveThemeState(state);
+    syncMyThemeRemote(state);
     myTick.value += 1;
 }