feat(audit): 审计日志保留期清理（后端自动清理 + 审计页配置） (#83)

审计日志新增可配置保留期：AuditLogRepository.DeleteBefore + AuditService 保留期监控（每 6h 读取 audit_retention_days，0/缺省=永久保留）；审计页新增管理员保留天数配置控件。后端 go test、前端 tsc+vite 通过。

server/internal/app/app.go

@@ -114,6 +114,8 @@ func New(ctx context.Context, cfg config.Config, version string) (*Application,
 	schedulerService.SetAuditRecorder(auditService)
 	// 审计日志外输：启动时用当前 settings 初始化 webhook，后续前端修改立即生效
 	settingsService.SetAuditWebhookConfigurer(ctx, auditService)
+	// 审计日志保留期清理：每 6h 读取 audit_retention_days 设置并清理超期日志（0/缺省=永久保留）
+	auditService.StartRetentionMonitor(ctx, systemConfigRepo, 6*time.Hour)
 
 	// Database discovery（集群依赖在 agentService 创建后注入）
 	databaseDiscoveryService := service.NewDatabaseDiscoveryService(backup.NewOSCommandExecutor())

server/internal/repository/audit_log_repository.go

@@ -29,6 +29,8 @@ type AuditLogRepository interface {
 	Create(ctx context.Context, log *model.AuditLog) error
 	List(ctx context.Context, opts AuditLogListOptions) (*AuditLogListResult, error)
 	ListAll(ctx context.Context, opts AuditLogListOptions) ([]model.AuditLog, error)
+	// DeleteBefore 删除 created_at 早于 cutoff 的审计日志，返回删除行数。用于保留期清理。
+	DeleteBefore(ctx context.Context, cutoff time.Time) (int64, error)
 }
 
 type gormAuditLogRepository struct {
@@ -43,6 +45,11 @@ func (r *gormAuditLogRepository) Create(_ context.Context, log *model.AuditLog)
 	return r.db.Create(log).Error
 }
 
+func (r *gormAuditLogRepository) DeleteBefore(ctx context.Context, cutoff time.Time) (int64, error) {
+	result := r.db.WithContext(ctx).Where("created_at < ?", cutoff).Delete(&model.AuditLog{})
+	return result.RowsAffected, result.Error
+}
+
 func (r *gormAuditLogRepository) List(_ context.Context, opts AuditLogListOptions) (*AuditLogListResult, error) {
 	query := r.buildQuery(opts)
 	var total int64

server/internal/service/audit_retention_test.go

@@ -0,0 +1,86 @@
+package service
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"backupx/server/internal/config"
+	"backupx/server/internal/database"
+	"backupx/server/internal/logger"
+	"backupx/server/internal/model"
+	"backupx/server/internal/repository"
+)
+
+func TestAuditRetention(t *testing.T) {
+	baseDir := t.TempDir()
+	log, err := logger.New(config.LogConfig{Level: "error"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	db, err := database.Open(config.DatabaseConfig{Path: filepath.Join(baseDir, "a.db")}, log)
+	if err != nil {
+		t.Fatal(err)
+	}
+	auditRepo := repository.NewAuditLogRepository(db)
+	configRepo := repository.NewSystemConfigRepository(db)
+	svc := NewAuditService(auditRepo)
+	ctx := context.Background()
+
+	// seed 写一条审计日志并把 created_at 强制改到 daysAgo 天前。
+	seed := func(daysAgo int) {
+		rec := &model.AuditLog{Username: "t", Category: "test", Action: "seed"}
+		if err := auditRepo.Create(ctx, rec); err != nil {
+			t.Fatalf("create: %v", err)
+		}
+		ts := time.Now().UTC().AddDate(0, 0, -daysAgo)
+		if err := db.Model(&model.AuditLog{}).Where("id = ?", rec.ID).Update("created_at", ts).Error; err != nil {
+			t.Fatalf("backdate: %v", err)
+		}
+	}
+	count := func() int64 {
+		var n int64
+		db.Model(&model.AuditLog{}).Count(&n)
+		return n
+	}
+
+	seed(100)
+	seed(40)
+	seed(0)
+	if count() != 3 {
+		t.Fatalf("expected 3 seeded, got %d", count())
+	}
+
+	// days<=0 不清理。
+	if n, _ := svc.PurgeOlderThan(ctx, 0); n != 0 || count() != 3 {
+		t.Fatalf("days<=0 must not purge (n=%d count=%d)", n, count())
+	}
+
+	// 保留 50 天 → 删除 100 天前那条。
+	n, err := svc.PurgeOlderThan(ctx, 50)
+	if err != nil {
+		t.Fatalf("purge: %v", err)
+	}
+	if n != 1 || count() != 2 {
+		t.Fatalf("expected 1 purged / 2 remaining, got n=%d count=%d", n, count())
+	}
+
+	// 设置驱动：retention=10 天 → 再删 40 天前那条。
+	if err := configRepo.Upsert(ctx, &model.SystemConfig{Key: SettingKeyAuditRetentionDays, Value: "10"}); err != nil {
+		t.Fatalf("upsert setting: %v", err)
+	}
+	svc.runRetentionOnce(ctx, configRepo)
+	if count() != 1 {
+		t.Fatalf("expected 1 remaining after retention=10, got %d", count())
+	}
+
+	// retention=0 → 永久保留，不再删除。
+	if err := configRepo.Upsert(ctx, &model.SystemConfig{Key: SettingKeyAuditRetentionDays, Value: "0"}); err != nil {
+		t.Fatalf("upsert setting: %v", err)
+	}
+	svc.runRetentionOnce(ctx, configRepo)
+	if count() != 1 {
+		t.Fatalf("retention=0 must keep all, got %d", count())
+	}
+}

server/internal/service/audit_service.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"log"
 	"net/http"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -51,6 +52,59 @@ func NewAuditService(repo repository.AuditLogRepository) *AuditService {
 	}
 }
 
+// PurgeOlderThan 删除早于 days 天前的审计日志，返回删除条数。days<=0 时不清理。
+func (s *AuditService) PurgeOlderThan(ctx context.Context, days int) (int64, error) {
+	if days <= 0 {
+		return 0, nil
+	}
+	cutoff := time.Now().UTC().AddDate(0, 0, -days)
+	return s.repo.DeleteBefore(ctx, cutoff)
+}
+
+// StartRetentionMonitor 启动后台审计保留期清理：按 interval 周期读取
+// audit_retention_days 设置，>0 时删除超期审计日志。缺省/0 表示永久保留
+// （向后兼容，默认不删任何历史）。ctx 取消后退出。
+func (s *AuditService) StartRetentionMonitor(ctx context.Context, configs repository.SystemConfigRepository, interval time.Duration) {
+	if s == nil || configs == nil {
+		return
+	}
+	if interval <= 0 {
+		interval = 6 * time.Hour
+	}
+	go func() {
+		ticker := time.NewTicker(interval)
+		defer ticker.Stop()
+		s.runRetentionOnce(ctx, configs) // 启动后立即跑一次
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-ticker.C:
+				s.runRetentionOnce(ctx, configs)
+			}
+		}
+	}()
+}
+
+func (s *AuditService) runRetentionOnce(ctx context.Context, configs repository.SystemConfigRepository) {
+	cfg, err := configs.GetByKey(ctx, SettingKeyAuditRetentionDays)
+	if err != nil || cfg == nil {
+		return
+	}
+	days, err := strconv.Atoi(strings.TrimSpace(cfg.Value))
+	if err != nil || days <= 0 {
+		return
+	}
+	deleted, err := s.PurgeOlderThan(ctx, days)
+	if err != nil {
+		log.Printf("[audit] retention purge failed: %v", err)
+		return
+	}
+	if deleted > 0 {
+		log.Printf("[audit] retention purge: deleted %d logs older than %d days", deleted, days)
+	}
+}
+
 // SetWebhook 动态配置审计事件转发 URL 与签名密钥。
 //   - url 为空字符串时禁用转发
 //   - secret 非空时对 payload 计算 HMAC-SHA256，作为 X-BackupX-Signature header

server/internal/service/audit_service_webhook_test.go

@@ -46,6 +46,10 @@ func (r *fakeAuditRepo) ListAll(context.Context, repository.AuditLogListOptions)
 	return nil, nil
 }
 
+func (r *fakeAuditRepo) DeleteBefore(context.Context, time.Time) (int64, error) {
+	return 0, nil
+}
+
 func TestAuditService_WebhookDeliversSignedPayload(t *testing.T) {
 	var hits atomic.Int32
 	var got struct {

server/internal/service/settings_service.go

@@ -47,6 +47,8 @@ const (
 	SettingKeyBandwidthLimit            = "bandwidth_limit"
 	SettingKeyAuditWebhookURL           = "audit_webhook_url"
 	SettingKeyAuditWebhookSecret        = "audit_webhook_secret"
+	// SettingKeyAuditRetentionDays 审计日志保留天数（0/缺省=永久保留）。
+	SettingKeyAuditRetentionDays = "audit_retention_days"
 )
 
 var settingsKeys = []string{
@@ -57,6 +59,7 @@ var settingsKeys = []string{
 	SettingKeyBandwidthLimit,
 	SettingKeyAuditWebhookURL,
 	SettingKeyAuditWebhookSecret,
+	SettingKeyAuditRetentionDays,
 }
 
 func (s *SettingsService) GetAll(ctx context.Context) (map[string]string, error) {