diff --git a/src/main/java/com/yunhai/userhome/controller/api/SchSettingsController.java b/src/main/java/com/yunhai/userhome/controller/api/SchSettingsController.java
index 3a5d9d0..08dcd43 100644
--- a/src/main/java/com/yunhai/userhome/controller/api/SchSettingsController.java
+++ b/src/main/java/com/yunhai/userhome/controller/api/SchSettingsController.java
@@ -1,10 +1,15 @@
 package com.yunhai.userhome.controller.api;
 
+import com.yunhai.platform.utils.exception.DException;
 import com.yunhai.platform.utils.model.BoaUser;
 import com.yunhai.userhome.config.Config;
 import com.yunhai.userhome.entity.SchSettings;
+import com.yunhai.userhome.entity.UserCurrentRole;
 import com.yunhai.userhome.service.ISchSettingsService;
+import com.yunhai.userhome.service.IUserCurrentRoleService;
+import com.yunhai.userhome.utils.OtherUtil;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.util.StringUtils;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -12,20 +17,34 @@ import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
 import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.Optional;
 
 /**
  * 学校设置接口（CAS 登录态，路径 {@code /{platform}/}），对齐旧 UserHome SchSettingsController。
  * <p>getSchSettings 查本地 sch_settings 表（不再依赖跨仓 schConfig）；
  * saveSchTheme/saveSchLogo 写本地 sch_settings 表。</p>
+ * <p>主题设置轮（2026-09-30）新增学校默认主题档三接口（契约见 YschTheme《主题设置与通道改动-执行方案》§3.5）：
+ * schTheme 读（已登录可读，可空不兜底——与 getSchSettings 的兜底语义刻意区分）；
+ * saveSchThemeState 写（仅学校管理员/超管）；clearSchTheme 清空（置空 theme 字段——sch_settings 行还承载
+ * logo 等字段不能删行，置空后读侧返回 null，效果等同"未配置"）。存储形态：theme_name 列存紧凑四段编码
+ * {@code theme|sideDeep01|gradOn01|sideFollow01}（如 teal|0|1|1；不拆列、零 DDL，列宽未确认故不存整份 JSON；
+ * 旧格式值/非法值读侧一律视同未配置）。</p>
  */
 @RestController
 @RequestMapping(value = Config.API_PATH)
 public class SchSettingsController {
 
+    /** 合法档位（与通道 THEME_NAMES 一致；防旧库脏值意外生效） */
+    private static final String[] THEME_KEYS = {"blue", "ocean", "ink", "violet", "teal"};
+
     @Autowired
     private ISchSettingsService schSettingsService;
 
+    @Autowired
+    private IUserCurrentRoleService userCurrentRoleService;
+
     private Integer resolveSchId(BoaUser user) {
         if (user.getSchool() != null) {
             return user.getSchool().getId();
@@ -36,6 +55,114 @@ public class SchSettingsController {
         return 0;
     }
 
+    /** 主题档的目标学校：超管=显式 schId 或 0（平台默认层）；其余=当前角色学校（兜底主归属） */
+    private Integer resolveThemeSchId(BoaUser user, Integer explicitSchId) {
+        if (user.getType() != null && user.getType() == 1) {
+            return explicitSchId == null ? 0 : explicitSchId;
+        }
+        return userCurrentRoleService.findById(user.getId())
+                .map(UserCurrentRole::getSchId)
+                .filter(schId -> schId != null && schId > 0)
+                .orElseGet(() -> resolveSchId(user));
+    }
+
+    /** 主题档写权限：超管或学校管理员（先例：UserSettingsServiceImpl.findSchWallpaperManageList） */
+    private void requireThemeAdmin(BoaUser user) {
+        boolean superAdmin = user.getType() != null && user.getType() == 1;
+        if (!superAdmin) {
+            Optional<UserCurrentRole> currentRole = userCurrentRoleService.findById(user.getId());
+            if (!currentRole.isPresent() || !OtherUtil.isAdminById(currentRole.get().getRoleId())) {
+                throw new DException("仅学校管理员可配置本校默认主题");
+            }
+        }
+    }
+
+    /** 紧凑编码 → ThemeState JSON；非本编码形态（旧档名/脏值/字段非法）一律 null（视同未配置） */
+    private static String decodeThemeState(String encoded) {
+        if (!StringUtils.hasText(encoded)) return null;
+        String[] parts = encoded.trim().split("\\|");
+        if (parts.length != 4) return null;
+        if (!isThemeKey(parts[0])) return null;
+        for (int i = 1; i < 4; i++) {
+            if (parts[i].length() != 1 || (parts[i].charAt(0) != '0' && parts[i].charAt(0) != '1')) return null;
+        }
+        return "{\"theme\":\"" + parts[0] + "\",\"sideDeep\":" + parts[1]
+                + ",\"gradOn\":" + parts[2] + ",\"sideFollow\":" + parts[3] + "}";
+    }
+
+    /** ThemeState JSON 校验（四字段齐全、档名合法）+ → 紧凑编码；非法抛业务异常（写入侧从严） */
+    private static String encodeThemeState(String themeStateJson) {
+        if (!StringUtils.hasText(themeStateJson)) throw new DException("主题档不能为空");
+        com.fasterxml.jackson.databind.JsonNode n;
+        try {
+            n = new com.fasterxml.jackson.databind.ObjectMapper().readTree(themeStateJson);
+        } catch (Exception e) {
+            throw new DException("主题档格式不合法");
+        }
+        if (n == null || !n.isObject() || !n.hasNonNull("theme") || !n.has("sideDeep") || !n.has("gradOn") || !n.has("sideFollow")) {
+            throw new DException("主题档格式不合法");
+        }
+        String theme = n.get("theme").asText();
+        if (!isThemeKey(theme)) throw new DException("主题档名不合法: " + theme);
+        return theme + "|" + (n.get("sideDeep").asBoolean() ? 1 : 0)
+                + "|" + (n.get("gradOn").asBoolean() ? 1 : 0)
+                + "|" + (n.get("sideFollow").asBoolean() ? 1 : 0);
+    }
+
+    private static boolean isThemeKey(String theme) {
+        if (theme == null) return false;
+        for (String k : THEME_KEYS) {
+            if (k.equals(theme)) return true;
+        }
+        return false;
+    }
+
+    /**
+     * 学校默认主题档（已登录可读）：{themeState: "<ThemeState JSON>" | null, schId}。
+     * 未配置/旧格式值/脏数据 → themeState=null（前端"不写键、不报错"）。
+     */
+    @GetMapping("schTheme")
+    public Map<String, Object> schTheme(BoaUser authUserWithDept) {
+        Integer schId = resolveThemeSchId(authUserWithDept, null);
+        String themeState = schSettingsService.findBySchIdRaw(schId)
+                .map(SchSettings::getThemeName)
+                .map(SchSettingsController::decodeThemeState)
+                .orElse(null);
+        Map<String, Object> out = new HashMap<>();
+        out.put("themeState", themeState);
+        out.put("schId", schId);
+        return out;
+    }
+
+    /** 保存学校默认主题档（仅学校管理员/超管）：themeState 为整份 ThemeState JSON，服务端转紧凑编码存 theme_name。 */
+    @PostMapping("saveSchThemeState")
+    public void saveSchThemeState(BoaUser authUserWithDept,
+                                  @RequestParam("themeState") String themeState,
+                                  @RequestParam(name = "schId", required = false) Integer schId) {
+        requireThemeAdmin(authUserWithDept);
+        Integer targetSchId = resolveThemeSchId(authUserWithDept, schId);
+        String encoded = encodeThemeState(themeState);
+        SchSettings schSettings = schSettingsService.findBySchIdRaw(targetSchId).orElseGet(SchSettings::new);
+        schSettings.setCDate(new Date());
+        schSettings.setSchId(targetSchId);
+        schSettings.setCId(authUserWithDept.getId());
+        schSettings.setThemeName(encoded);
+        schSettingsService.save(schSettings);
+    }
+
+    /** 清空学校默认主题（仅管理员）：置空 theme 字段（行还承载 logo 等配置不能删行；置空后读侧返回 null）。 */
+    @PostMapping("clearSchTheme")
+    public void clearSchTheme(BoaUser authUserWithDept,
+                              @RequestParam(name = "schId", required = false) Integer schId) {
+        requireThemeAdmin(authUserWithDept);
+        Integer targetSchId = resolveThemeSchId(authUserWithDept, schId);
+        Optional<SchSettings> existing = schSettingsService.findBySchIdRaw(targetSchId);
+        if (!existing.isPresent()) return;
+        SchSettings schSettings = existing.get();
+        schSettings.setThemeName(null);
+        schSettingsService.save(schSettings);
+    }
+
     @PostMapping("saveSchTheme")
     public void saveSchTheme(BoaUser authUserWithDept, String themeName, @RequestParam(name = "schId", defaultValue = "0") Integer schId) {
         if (schId == null || schId == 0) {
diff --git a/src/main/java/com/yunhai/userhome/service/ISchSettingsService.java b/src/main/java/com/yunhai/userhome/service/ISchSettingsService.java
index f318d36..ec0742d 100644
--- a/src/main/java/com/yunhai/userhome/service/ISchSettingsService.java
+++ b/src/main/java/com/yunhai/userhome/service/ISchSettingsService.java
@@ -12,5 +12,8 @@ public interface ISchSettingsService {
 
     Optional<SchSettings> findBySchId(Integer schId);
 
+    /** 原样读（无兜底）：学校默认主题档等"可空语义"场景专用——查无返回 empty，不合成默认对象 */
+    Optional<SchSettings> findBySchIdRaw(Integer schId);
+
     List<SchSettings> findBySchIds(List<Integer> schIds);
 }
diff --git a/src/main/java/com/yunhai/userhome/service/impl/SchSettingsServiceImpl.java b/src/main/java/com/yunhai/userhome/service/impl/SchSettingsServiceImpl.java
index d36243e..cb73406 100644
--- a/src/main/java/com/yunhai/userhome/service/impl/SchSettingsServiceImpl.java
+++ b/src/main/java/com/yunhai/userhome/service/impl/SchSettingsServiceImpl.java
@@ -23,6 +23,11 @@ public class SchSettingsServiceImpl implements ISchSettingsService {
         schSettingsRepository.save(schSettings);
     }
 
+    @Override
+    public Optional<SchSettings> findBySchIdRaw(Integer schId) {
+        return schSettingsRepository.findFirstBySchId(schId);
+    }
+
     @Override
     public Optional<SchSettings> findBySchId(Integer schId) {
         Optional<SchSettings> local = schSettingsRepository.findFirstBySchId(schId);