diff --git a/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/controller/TranscodeNoticeController.java b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/controller/TranscodeNoticeController.java
new file mode 100644
index 0000000..2f2e143
--- /dev/null
+++ b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/controller/TranscodeNoticeController.java
@@ -0,0 +1,33 @@
+// Author: fruit.com.cn
+// 后台转码通知接口。
+
+package com.fruitshorts.admin.controller;
+
+import com.fruitshorts.admin.service.TranscodeNoticeService;
+import com.fruitshorts.admin.vo.TranscodeNoticeRespVO;
+import com.fruitshorts.common.pojo.Result;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import lombok.RequiredArgsConstructor;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/** 后台转码通知。 */
+@Tag(name = "后台-转码通知")
+@RestController
+@RequestMapping("/admin/notifications")
+@RequiredArgsConstructor
+public class TranscodeNoticeController {
+
+    private final TranscodeNoticeService transcodeNoticeService;
+
+    /** 转码中、成功、失败的角标和最近任务，含短剧与集数。 */
+    @Operation(summary = "转码通知（角标与最近任务）")
+    @GetMapping("/transcode")
+    @PreAuthorize("@ss.hasPermission('drama:list')")
+    public Result<TranscodeNoticeRespVO> transcode() {
+        return Result.ok(transcodeNoticeService.notices());
+    }
+}
diff --git a/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/service/DashboardService.java b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/service/DashboardService.java
index 277d645..14df550 100644
--- a/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/service/DashboardService.java
+++ b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/service/DashboardService.java
@@ -58,7 +58,11 @@ import org.springframework.jdbc.core.JdbcTemplate;
  * <ul>
  *   <li>用户：`total` = app_user 未删除总数；`newToday`/`new7d` = 按 created_at 落在当天 / 近 7 天；
  *       `active7d` = last_login_at 在近 7 天内（**不是 DAU**：真正的日活需要按天留存登录快照，
- *       当前没有逐日快照数据源，见 notes）；`banned`/`limited` = 按 status 计数。</li>
+ *       当前没有逐日快照数据源，见 notes）；`androidActive7d`/`iosActive7d` =
+ *       `app_user_device` 中状态为 active、近 7 天有心跳的去重设备数；
+ *       `retention1d` = 昨日注册用户中今天仍登录的比例，分母为 0 时返回 null；
+ *       `retention7d` = 8 至 14 天前注册的用户中，近 7 天仍登录的比例，分母为 0 时返回 null；
+ *       `banned`/`limited` = 按 status 计数。</li>
  *   <li>内容：短剧按 status 计数（`reviewing` 视为待审、`published` 视为已上线）；
  *       剧集总数与已上线数；`episodeWithMedia` = video_url 非空的剧集数。</li>
  *   <li>播放：`viewTotal`/`playTotal` = 短剧表上累计计数列的求和（累计口径，不限定时间范围）；
@@ -76,6 +80,9 @@ import org.springframework.jdbc.core.JdbcTemplate;
 public class DashboardService {
 
     private static final int ACTIVE_WINDOW_DAYS = 7;
+    private static final int RETENTION_WINDOW_DAYS = 7;
+    private static final String PLATFORM_ANDROID = "ANDROID";
+    private static final String PLATFORM_IOS = "IOS";
 
     private final AppUserMapper appUserMapper;
     private final AppUserOtpMapper appUserOtpMapper;
@@ -187,9 +194,47 @@ public class DashboardService {
         user.put("limited", countUser(Wrappers.<AppUser>lambdaQuery().eq(AppUser::getStatus, "limited")));
         user.put("deactivated", countUser(Wrappers.<AppUser>lambdaQuery()
                 .eq(AppUser::getStatus, "deactivated")));
+        putActiveDevices(user, sevenDaysAgo);
+        user.put("retention1d", retentionRate(todayStart.minusDays(1), todayStart, todayStart));
+        user.put("retention7d", retentionRate(
+                todayStart.minusDays(RETENTION_WINDOW_DAYS * 2L),
+                todayStart.minusDays(RETENTION_WINDOW_DAYS),
+                sevenDaysAgo));
         return user;
     }
 
+    /** 近 7 天仍活跃的安卓、iOS 设备，按设备号去重。 */
+    private void putActiveDevices(Map<String, Object> user, LocalDateTime since) {
+        Map<String, Long> counts = new LinkedHashMap<>();
+        jdbcTemplate.query("""
+                SELECT UPPER(platform), COUNT(DISTINCT device_id)
+                FROM app_user_device
+                WHERE deleted = 0 AND status = 'active' AND last_seen_at >= ?
+                GROUP BY UPPER(platform)
+                """, rs -> {
+            counts.put(rs.getString(1), rs.getLong(2));
+        }, since);
+        user.put("androidActive7d", counts.getOrDefault(PLATFORM_ANDROID, 0L));
+        user.put("iosActive7d", counts.getOrDefault(PLATFORM_IOS, 0L));
+    }
+
+    /** 队列留存率。注册队列为空时返回 null，避免把没有样本显示成 0%。 */
+    private Double retentionRate(LocalDateTime cohortStart, LocalDateTime cohortEnd, LocalDateTime returnedSince) {
+        Long cohort = jdbcTemplate.queryForObject("""
+                SELECT COUNT(*) FROM app_user
+                WHERE deleted = 0 AND created_at >= ? AND created_at < ?
+                """, Long.class, cohortStart, cohortEnd);
+        if (cohort == null || cohort == 0L) {
+            return null;
+        }
+        Long returned = jdbcTemplate.queryForObject("""
+                SELECT COUNT(*) FROM app_user
+                WHERE deleted = 0 AND created_at >= ? AND created_at < ? AND last_login_at >= ?
+                """, Long.class, cohortStart, cohortEnd, returnedSince);
+        long back = returned == null ? 0L : returned;
+        return Math.round(back * 1000.0 / cohort) / 1000.0;
+    }
+
     private Map<String, Object> contentMetrics() {
         Map<String, Object> content = new LinkedHashMap<>();
         content.put("dramaTotal", dramaMapper.selectCount(null));
@@ -284,6 +329,8 @@ public class DashboardService {
         List<String> notes = new ArrayList<>();
         notes.add("DAU 暂无数据源：需要按天留存登录快照（ops_daily_stat 已建表但当前无产出），"
                 + "现以 active7d（近 7 天登录过）近似");
+        notes.add("androidActive7d / iosActive7d 是近 7 天 last_seen_at 仍活跃的去重设备，不是安装量");
+        notes.add("retention1d 是昨日注册且今天仍登录的比例；retention7d 是 8 至 14 天前注册、近 7 天仍登录的比例；队列为空时为 null");
         notes.add("CDN 流量与带宽成本暂无数据源：需接入 CDN 账单或访问日志，cdnTrafficBytes 恒为 null");
         notes.add("收入金额在商店未接入前恒为 0：订单表无真实商店订单，金币解锁收入请参考 coinConsumed");
         notes.add("viewTotal/playTotal 是短剧表上的累计计数，与 playEvents7d 的流水口径不可相加");
diff --git a/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/service/TranscodeNoticeService.java b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/service/TranscodeNoticeService.java
new file mode 100644
index 0000000..5c96670
--- /dev/null
+++ b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/service/TranscodeNoticeService.java
@@ -0,0 +1,84 @@
+// Author: fruit.com.cn
+// 转码通知：按状态计数，并带出短剧与集数。
+
+package com.fruitshorts.admin.service;
+
+import com.fruitshorts.admin.vo.TranscodeNoticeRespVO;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+
+/**
+ * 转码通知。
+ * 转码中、成功、失败分别计数，列表带出短剧名和集数。
+ */
+@Service
+public class TranscodeNoticeService {
+
+    private static final int NOTICE_LIMIT = 20;
+    private static final String STATUS_RUNNING = "RUNNING";
+    private static final String STATUS_SUCCESS = "SUCCESS";
+    private static final String STATUS_FAILED = "FAILED";
+    private static final String UNKNOWN_DRAMA = "未关联短剧";
+
+    private final JdbcTemplate jdbcTemplate;
+
+    public TranscodeNoticeService(JdbcTemplate jdbcTemplate) {
+        this.jdbcTemplate = jdbcTemplate;
+    }
+
+    /** 角标数量和最近 20 条转码中、成功、失败任务。 */
+    public TranscodeNoticeRespVO notices() {
+        TranscodeNoticeRespVO data = new TranscodeNoticeRespVO();
+        fillCounts(data);
+        data.setRunningList(latest(STATUS_RUNNING));
+        data.setSuccessList(latest(STATUS_SUCCESS));
+        data.setFailedList(latest(STATUS_FAILED));
+        return data;
+    }
+
+    private void fillCounts(TranscodeNoticeRespVO data) {
+        jdbcTemplate.query("""
+                SELECT status, COUNT(*)
+                FROM transcode_task
+                WHERE deleted = 0 AND status IN (?, ?, ?)
+                GROUP BY status
+                """, rs -> {
+            long count = rs.getLong(2);
+            switch (rs.getString(1)) {
+                case STATUS_RUNNING -> data.setRunning(count);
+                case STATUS_SUCCESS -> data.setSuccess(count);
+                case STATUS_FAILED -> data.setFailed(count);
+                default -> {
+                }
+            }
+        }, STATUS_RUNNING, STATUS_SUCCESS, STATUS_FAILED);
+    }
+
+    private List<TranscodeNoticeRespVO.Item> latest(String status) {
+        return jdbcTemplate.query("""
+                SELECT t.id, t.status, t.progress, t.error_msg, t.updated_at,
+                       COALESCE(NULLIF(d.title, ''), NULLIF(d2.title, ''), ?) AS drama_title,
+                       e.ep_no, e.title
+                FROM transcode_task t
+                LEFT JOIN drama_episode e ON e.id = t.episode_id AND e.deleted = 0
+                LEFT JOIN drama d ON d.id = t.drama_id AND d.deleted = 0
+                LEFT JOIN drama d2 ON d2.id = e.drama_id AND d2.deleted = 0
+                WHERE t.deleted = 0 AND t.status = ?
+                ORDER BY t.updated_at DESC
+                LIMIT ?
+                """, (rs, row) -> {
+            TranscodeNoticeRespVO.Item item = new TranscodeNoticeRespVO.Item();
+            item.setId(rs.getLong("id"));
+            item.setStatus(rs.getString("status"));
+            item.setProgress(rs.getInt("progress"));
+            item.setErrorMsg(rs.getString("error_msg"));
+            item.setUpdatedAt(rs.getTimestamp("updated_at").toLocalDateTime());
+            item.setDramaTitle(rs.getString("drama_title"));
+            item.setEpisodeNo((Integer) rs.getObject("ep_no"));
+            item.setEpisodeTitle(rs.getString("title"));
+            return item;
+        }, UNKNOWN_DRAMA, status, NOTICE_LIMIT);
+    }
+}
diff --git a/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/vo/TranscodeNoticeRespVO.java b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/vo/TranscodeNoticeRespVO.java
new file mode 100644
index 0000000..afdf892
--- /dev/null
+++ b/fruitshorts-admin-api/src/main/java/com/fruitshorts/admin/vo/TranscodeNoticeRespVO.java
@@ -0,0 +1,35 @@
+// Author: fruit.com.cn
+// 转码通知响应：角标数量和最近任务。
+
+package com.fruitshorts.admin.vo;
+
+import lombok.Data;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+
+/** 转码通知：角标数量和最近任务。 */
+@Data
+public class TranscodeNoticeRespVO {
+
+    private long running;
+    private long success;
+    private long failed;
+    private List<Item> runningList = new ArrayList<>();
+    private List<Item> successList = new ArrayList<>();
+    private List<Item> failedList = new ArrayList<>();
+
+    /** 一条转码通知，带短剧和集数。 */
+    @Data
+    public static class Item {
+        private Long id;
+        private String status;
+        private String dramaTitle;
+        private Integer episodeNo;
+        private String episodeTitle;
+        private Integer progress;
+        private String errorMsg;
+        private LocalDateTime updatedAt;
+    }
+}
diff --git a/fruitshorts-admin-api/src/test/java/com/fruitshorts/admin/controller/TranscodeNoticeContractTest.java b/fruitshorts-admin-api/src/test/java/com/fruitshorts/admin/controller/TranscodeNoticeContractTest.java
new file mode 100644
index 0000000..e5e8e29
--- /dev/null
+++ b/fruitshorts-admin-api/src/test/java/com/fruitshorts/admin/controller/TranscodeNoticeContractTest.java
@@ -0,0 +1,53 @@
+// Author: fruit.com.cn
+
+package com.fruitshorts.admin.controller;
+
+import com.fruitshorts.admin.service.TranscodeNoticeService;
+import com.fruitshorts.admin.support.ControllerContractSupport;
+import com.fruitshorts.admin.vo.TranscodeNoticeRespVO;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.test.web.servlet.MockMvc;
+
+import java.util.List;
+
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+class TranscodeNoticeContractTest {
+
+    private TranscodeNoticeService transcodeNoticeService;
+    private MockMvc mockMvc;
+
+    @BeforeEach
+    void setUp() {
+        transcodeNoticeService = mock(TranscodeNoticeService.class);
+        mockMvc = ControllerContractSupport.mockMvcOf(new TranscodeNoticeController(transcodeNoticeService));
+    }
+
+    @Test
+    void should_return_drama_and_episode_when_transcode_notice_is_requested() throws Exception {
+        TranscodeNoticeRespVO data = new TranscodeNoticeRespVO();
+        data.setRunning(1L);
+        data.setSuccess(2L);
+        data.setFailed(3L);
+        TranscodeNoticeRespVO.Item item = new TranscodeNoticeRespVO.Item();
+        item.setDramaTitle("重生");
+        item.setEpisodeNo(4);
+        item.setEpisodeTitle("第4集");
+        data.setFailedList(List.of(item));
+        given(transcodeNoticeService.notices()).willReturn(data);
+
+        mockMvc.perform(get("/admin/notifications/transcode"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.data.running").value(1))
+                .andExpect(jsonPath("$.data.success").value(2))
+                .andExpect(jsonPath("$.data.failed").value(3))
+                .andExpect(jsonPath("$.data.failedList[0].dramaTitle").value("重生"))
+                .andExpect(jsonPath("$.data.failedList[0].episodeNo").value(4))
+                .andExpect(jsonPath("$.data.failedList[0].episodeTitle").value("第4集"));
+    }
+}
diff --git a/fruitshorts-admin-api/src/test/java/com/fruitshorts/admin/service/TranscodeNoticeServiceTest.java b/fruitshorts-admin-api/src/test/java/com/fruitshorts/admin/service/TranscodeNoticeServiceTest.java
new file mode 100644
index 0000000..012f1c9
--- /dev/null
+++ b/fruitshorts-admin-api/src/test/java/com/fruitshorts/admin/service/TranscodeNoticeServiceTest.java
@@ -0,0 +1,67 @@
+// Author: fruit.com.cn
+
+package com.fruitshorts.admin.service;
+
+import com.fruitshorts.admin.vo.TranscodeNoticeRespVO;
+import org.junit.jupiter.api.Test;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.core.RowCallbackHandler;
+import org.springframework.jdbc.core.RowMapper;
+
+import java.sql.ResultSet;
+import java.sql.Timestamp;
+import java.time.LocalDateTime;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doAnswer;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class TranscodeNoticeServiceTest {
+
+    @Test
+    void should_attach_drama_and_episode_when_failed_tasks_are_loaded() throws Exception {
+        JdbcTemplate jdbc = mock(JdbcTemplate.class);
+        doAnswer(invocation -> {
+            assertTrue(invocation.getArgument(0, String.class).contains("?"));
+            return null;
+        }).when(jdbc).query(anyString(), any(RowCallbackHandler.class), eq("RUNNING"), eq("SUCCESS"), eq("FAILED"));
+        when(jdbc.query(anyString(), any(RowMapper.class), any(), anyString(), any()))
+                .thenAnswer(invocation -> {
+                    String sql = invocation.getArgument(0, String.class);
+                    String status = invocation.getArgument(3, String.class);
+                    if (!"FAILED".equals(status)) {
+                        return java.util.List.of();
+                    }
+                    assertTrue(sql.contains("drama_title"));
+                    assertTrue(sql.contains("?"));
+                    RowMapper<?> mapper = invocation.getArgument(1);
+                    ResultSet rs = failedRow();
+                    return java.util.List.of(mapper.mapRow(rs, 0));
+                });
+
+        TranscodeNoticeRespVO data = new TranscodeNoticeService(jdbc).notices();
+
+        assertEquals(1, data.getFailedList().size());
+        assertEquals("重生", data.getFailedList().get(0).getDramaTitle());
+        assertEquals(4, data.getFailedList().get(0).getEpisodeNo());
+        assertEquals("第4集", data.getFailedList().get(0).getEpisodeTitle());
+    }
+
+    private ResultSet failedRow() throws Exception {
+        ResultSet rs = mock(ResultSet.class);
+        when(rs.getLong("id")).thenReturn(9L);
+        when(rs.getString("status")).thenReturn("FAILED");
+        when(rs.getInt("progress")).thenReturn(0);
+        when(rs.getString("error_msg")).thenReturn("boom");
+        when(rs.getTimestamp("updated_at")).thenReturn(Timestamp.valueOf(LocalDateTime.of(2026, 10, 24, 12, 0)));
+        when(rs.getString("drama_title")).thenReturn("重生");
+        when(rs.getObject("ep_no")).thenReturn(4);
+        when(rs.getString("title")).thenReturn("第4集");
+        return rs;
+    }
+}