fix: 后台加人人数改为事务内实际插入数

docs/DEVIATIONS.md

@@ -1786,7 +1786,7 @@ issue #3 未关闭，`feat/fix-3-downlink-deadlock` 未合入 `main`。下面是
    - 实际做法：`handleGroupAddMembers` 用加人前后 `group_members` 行数差得到 `added`；审计 `result` 用 `added` 与 `failed`（全跳过且无失败记 `noop`，不记 `ok`）；响应增加 `added`，`failed` 仍只含真正失败项。前端按 `added` 提示，已是成员不改成错误码。  
    - 原因：全是已有成员时旧逻辑审计成 ok、界面提示已加人，实际插入 0 行。  
    - 备选方案：把已是成员写入 `failed`（否决，会改变客户端错误语义）；扩展 `group.AddResult` 返回插入列表（可后续做，本波不改身份线接口）。  
-   - 影响：管理 API 加人成功体多 `added` 字段；契约文档示例仍写 `{"failed":[]}`，以本偏差为准。
+   - 影响：管理 API 加人成功体多 `added` 字段；契约文档示例仍写 `{"failed":[]}`，以本偏差为准。`added` 取写事务内实际插入数（`AddResult.Added`，不进端协议 JSON），不用事务外两次 COUNT 的差，避免并发加人/踢人把别人的变更算进本请求。
 
 ### 复审修复 R3-02
 

internal/admin/groups.go

@@ -316,13 +316,6 @@ func (h *Handler) handleGroupAddMembers(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	before, err := h.groupMemberCount(r.Context(), id)
-	if err != nil {
-		h.auditP(p, "group_add_members", id, "error", ip)
-		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
-		return
-	}
-
 	res, err := h.groups.AdminAddMembers(r.Context(), id, req.MemberIDs)
 	if err != nil {
 		h.writeGroupErr(w, p, "group_add_members", id, ip, err)
@@ -332,14 +325,7 @@ func (h *Handler) handleGroupAddMembers(w http.ResponseWriter, r *http.Request)
 	if failed == nil {
 		failed = []group.MemberFail{}
 	}
-
-	after, err := h.groupMemberCount(r.Context(), id)
-	if err != nil {
-		h.auditP(p, "group_add_members", id, "error", ip)
-		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
-		return
-	}
-	added := after - before
+	added := res.Added
 	if added < 0 {
 		added = 0
 	}
@@ -434,13 +420,6 @@ func (h *Handler) groupOwner(ctx context.Context, groupID string) (string, error
 	return owner, err
 }
 
-func (h *Handler) groupMemberCount(ctx context.Context, groupID string) (int, error) {
-	var n int
-	err := h.db.Read.QueryRowContext(ctx,
-		`SELECT COUNT(*) FROM group_members WHERE group_id = ?`, groupID).Scan(&n)
-	return n, err
-}
-
 func (h *Handler) groupSummary(ctx context.Context, groupID string) (map[string]any, error) {
 	var name, owner string
 	var created int64

internal/app/group/app.go

@@ -620,7 +620,7 @@ func (a *App) AdminAddMembers(ctx context.Context, groupID string, memberIDs []s
 		failed = append(failed, MemberFail{ID: id, Code: protocol.CodeGroupFull})
 	}
 	if len(toAdd) == 0 {
-		return AddResult{Failed: failed}, nil
+		return AddResult{Failed: failed, Added: 0}, nil
 	}
 	now := a.nowMs()
 	var inserted []string
@@ -664,7 +664,7 @@ func (a *App) AdminAddMembers(ctx context.Context, groupID string, memberIDs []s
 	for _, id := range inserted {
 		a.emit(ctx, notify, groupID, eventMemberAdded, id, now)
 	}
-	return AddResult{Failed: failed}, nil
+	return AddResult{Failed: failed, Added: len(inserted)}, nil
 }
 
 func (a *App) createAdmin(ctx context.Context, ownerID, name, gid string, members []protocol.GroupMemberIn) (CreateResult, error) {

internal/app/group/service.go

@@ -28,6 +28,8 @@ type CreateResult struct {
 // AddResult 是加人结果。
 type AddResult struct {
 	Failed []MemberFail `json:"failed,omitempty"`
+	// Added 是本请求在写事务内实际插入的人数。不进协议 JSON，供后台审计使用。
+	Added int `json:"-"`
 }
 
 // ListItem 是 group.list 一项。