diff --git a/backend/internal/handler/admin/ops_system_log_handler_test.go b/backend/internal/handler/admin/ops_system_log_handler_test.go
new file mode 100644
index 00000000..7528acd8
--- /dev/null
+++ b/backend/internal/handler/admin/ops_system_log_handler_test.go
@@ -0,0 +1,233 @@
+package admin
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/Wei-Shaw/sub2api/internal/server/middleware"
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/gin-gonic/gin"
+)
+
+type responseEnvelope struct {
+	Code    int             `json:"code"`
+	Message string          `json:"message"`
+	Data    json.RawMessage `json:"data"`
+}
+
+func newOpsSystemLogTestRouter(handler *OpsHandler, withUser bool) *gin.Engine {
+	gin.SetMode(gin.TestMode)
+	r := gin.New()
+	if withUser {
+		r.Use(func(c *gin.Context) {
+			c.Set(string(middleware.ContextKeyUser), middleware.AuthSubject{UserID: 99})
+			c.Next()
+		})
+	}
+	r.GET("/logs", handler.ListSystemLogs)
+	r.POST("/logs/cleanup", handler.CleanupSystemLogs)
+	r.GET("/logs/health", handler.GetSystemLogIngestionHealth)
+	return r
+}
+
+func TestOpsSystemLogHandler_ListUnavailable(t *testing.T) {
+	h := NewOpsHandler(nil)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/logs", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusServiceUnavailable {
+		t.Fatalf("status=%d, want 503", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_ListInvalidUserID(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/logs?user_id=abc", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status=%d, want 400", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_ListInvalidAccountID(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/logs?account_id=-1", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status=%d, want 400", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_ListMonitoringDisabled(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, &config.Config{
+		Ops: config.OpsConfig{Enabled: false},
+	}, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/logs", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusNotFound {
+		t.Fatalf("status=%d, want 404", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_ListSuccess(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/logs?time_range=30m&page=1&page_size=20", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusOK {
+		t.Fatalf("status=%d, want 200", w.Code)
+	}
+
+	var resp responseEnvelope
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("unmarshal response: %v", err)
+	}
+	if resp.Code != 0 {
+		t.Fatalf("unexpected response code: %+v", resp)
+	}
+}
+
+func TestOpsSystemLogHandler_CleanupUnauthorized(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/logs/cleanup", bytes.NewBufferString(`{"request_id":"r1"}`))
+	req.Header.Set("Content-Type", "application/json")
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusUnauthorized {
+		t.Fatalf("status=%d, want 401", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_CleanupInvalidPayload(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, true)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/logs/cleanup", bytes.NewBufferString(`{bad-json`))
+	req.Header.Set("Content-Type", "application/json")
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status=%d, want 400", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_CleanupInvalidTime(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, true)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/logs/cleanup", bytes.NewBufferString(`{"start_time":"bad","request_id":"r1"}`))
+	req.Header.Set("Content-Type", "application/json")
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status=%d, want 400", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_CleanupInvalidEndTime(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, true)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/logs/cleanup", bytes.NewBufferString(`{"end_time":"bad","request_id":"r1"}`))
+	req.Header.Set("Content-Type", "application/json")
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("status=%d, want 400", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_CleanupServiceUnavailable(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, true)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/logs/cleanup", bytes.NewBufferString(`{"request_id":"r1"}`))
+	req.Header.Set("Content-Type", "application/json")
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusServiceUnavailable {
+		t.Fatalf("status=%d, want 503", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_CleanupMonitoringDisabled(t *testing.T) {
+	svc := service.NewOpsService(nil, nil, &config.Config{
+		Ops: config.OpsConfig{Enabled: false},
+	}, nil, nil, nil, nil, nil, nil, nil, nil)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, true)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/logs/cleanup", bytes.NewBufferString(`{"request_id":"r1"}`))
+	req.Header.Set("Content-Type", "application/json")
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusNotFound {
+		t.Fatalf("status=%d, want 404", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_Health(t *testing.T) {
+	sink := service.NewOpsSystemLogSink(nil)
+	svc := service.NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, sink)
+	h := NewOpsHandler(svc)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/logs/health", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusOK {
+		t.Fatalf("status=%d, want 200", w.Code)
+	}
+}
+
+func TestOpsSystemLogHandler_HealthUnavailableAndMonitoringDisabled(t *testing.T) {
+	h := NewOpsHandler(nil)
+	r := newOpsSystemLogTestRouter(h, false)
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/logs/health", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusServiceUnavailable {
+		t.Fatalf("status=%d, want 503", w.Code)
+	}
+
+	svc := service.NewOpsService(nil, nil, &config.Config{
+		Ops: config.OpsConfig{Enabled: false},
+	}, nil, nil, nil, nil, nil, nil, nil, nil)
+	h = NewOpsHandler(svc)
+	r = newOpsSystemLogTestRouter(h, false)
+	w = httptest.NewRecorder()
+	req = httptest.NewRequest(http.MethodGet, "/logs/health", nil)
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusNotFound {
+		t.Fatalf("status=%d, want 404", w.Code)
+	}
+}
diff --git a/backend/internal/service/ops_log_runtime_test.go b/backend/internal/service/ops_log_runtime_test.go
new file mode 100644
index 00000000..658b4812
--- /dev/null
+++ b/backend/internal/service/ops_log_runtime_test.go
@@ -0,0 +1,570 @@
+package service
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"testing"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
+)
+
+type runtimeSettingRepoStub struct {
+	values     map[string]string
+	deleted    map[string]bool
+	setCalls   int
+	getValueFn func(key string) (string, error)
+	setFn      func(key, value string) error
+	deleteFn   func(key string) error
+}
+
+func newRuntimeSettingRepoStub() *runtimeSettingRepoStub {
+	return &runtimeSettingRepoStub{
+		values:  map[string]string{},
+		deleted: map[string]bool{},
+	}
+}
+
+func (s *runtimeSettingRepoStub) Get(ctx context.Context, key string) (*Setting, error) {
+	value, err := s.GetValue(ctx, key)
+	if err != nil {
+		return nil, err
+	}
+	return &Setting{Key: key, Value: value}, nil
+}
+
+func (s *runtimeSettingRepoStub) GetValue(_ context.Context, key string) (string, error) {
+	if s.getValueFn != nil {
+		return s.getValueFn(key)
+	}
+	value, ok := s.values[key]
+	if !ok {
+		return "", ErrSettingNotFound
+	}
+	return value, nil
+}
+
+func (s *runtimeSettingRepoStub) Set(_ context.Context, key, value string) error {
+	if s.setFn != nil {
+		if err := s.setFn(key, value); err != nil {
+			return err
+		}
+	}
+	s.values[key] = value
+	s.setCalls++
+	return nil
+}
+
+func (s *runtimeSettingRepoStub) GetMultiple(_ context.Context, keys []string) (map[string]string, error) {
+	out := make(map[string]string, len(keys))
+	for _, key := range keys {
+		if value, ok := s.values[key]; ok {
+			out[key] = value
+		}
+	}
+	return out, nil
+}
+
+func (s *runtimeSettingRepoStub) SetMultiple(_ context.Context, settings map[string]string) error {
+	for key, value := range settings {
+		s.values[key] = value
+	}
+	return nil
+}
+
+func (s *runtimeSettingRepoStub) GetAll(_ context.Context) (map[string]string, error) {
+	out := make(map[string]string, len(s.values))
+	for key, value := range s.values {
+		out[key] = value
+	}
+	return out, nil
+}
+
+func (s *runtimeSettingRepoStub) Delete(_ context.Context, key string) error {
+	if s.deleteFn != nil {
+		if err := s.deleteFn(key); err != nil {
+			return err
+		}
+	}
+	if _, ok := s.values[key]; !ok {
+		return ErrSettingNotFound
+	}
+	delete(s.values, key)
+	s.deleted[key] = true
+	return nil
+}
+
+func TestUpdateRuntimeLogConfig_InvalidConfigShouldNotApply(t *testing.T) {
+	repo := newRuntimeSettingRepoStub()
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "info",
+				Caller:          true,
+				StacktraceLevel: "error",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+		},
+	}
+
+	if err := logger.Init(logger.InitOptions{
+		Level:       "info",
+		Format:      "json",
+		ServiceName: "sub2api",
+		Environment: "test",
+		Output: logger.OutputOptions{
+			ToStdout: true,
+			ToFile:   false,
+		},
+	}); err != nil {
+		t.Fatalf("init logger: %v", err)
+	}
+
+	_, err := svc.UpdateRuntimeLogConfig(context.Background(), &OpsRuntimeLogConfig{
+		Level:           "trace",
+		EnableSampling:  true,
+		SamplingInitial: 100,
+		SamplingNext:    100,
+		Caller:          true,
+		StacktraceLevel: "error",
+		RetentionDays:   30,
+	}, 1)
+	if err == nil {
+		t.Fatalf("expected validation error")
+	}
+	if logger.CurrentLevel() != "info" {
+		t.Fatalf("logger level changed unexpectedly: %s", logger.CurrentLevel())
+	}
+	if repo.setCalls != 1 {
+		// GetRuntimeLogConfig() 会在 key 缺失时写入默认值，此处应只有这一次持久化。
+		t.Fatalf("unexpected set calls: %d", repo.setCalls)
+	}
+}
+
+func TestResetRuntimeLogConfig_ShouldFallbackToBaseline(t *testing.T) {
+	repo := newRuntimeSettingRepoStub()
+	existing := &OpsRuntimeLogConfig{
+		Level:           "debug",
+		EnableSampling:  true,
+		SamplingInitial: 50,
+		SamplingNext:    50,
+		Caller:          true,
+		StacktraceLevel: "error",
+		RetentionDays:   60,
+		Source:          "runtime_setting",
+	}
+	raw, _ := json.Marshal(existing)
+	repo.values[SettingKeyOpsRuntimeLogConfig] = string(raw)
+
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "warn",
+				Caller:          false,
+				StacktraceLevel: "fatal",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+			Ops: config.OpsConfig{
+				Cleanup: config.OpsCleanupConfig{
+					ErrorLogRetentionDays: 45,
+				},
+			},
+		},
+	}
+
+	if err := logger.Init(logger.InitOptions{
+		Level:       "debug",
+		Format:      "json",
+		ServiceName: "sub2api",
+		Environment: "test",
+		Output: logger.OutputOptions{
+			ToStdout: true,
+			ToFile:   false,
+		},
+	}); err != nil {
+		t.Fatalf("init logger: %v", err)
+	}
+
+	resetCfg, err := svc.ResetRuntimeLogConfig(context.Background(), 9)
+	if err != nil {
+		t.Fatalf("ResetRuntimeLogConfig() error: %v", err)
+	}
+	if resetCfg.Source != "baseline" {
+		t.Fatalf("source = %q, want baseline", resetCfg.Source)
+	}
+	if resetCfg.Level != "warn" {
+		t.Fatalf("level = %q, want warn", resetCfg.Level)
+	}
+	if resetCfg.RetentionDays != 45 {
+		t.Fatalf("retention_days = %d, want 45", resetCfg.RetentionDays)
+	}
+	if logger.CurrentLevel() != "warn" {
+		t.Fatalf("logger level = %q, want warn", logger.CurrentLevel())
+	}
+	if !repo.deleted[SettingKeyOpsRuntimeLogConfig] {
+		t.Fatalf("runtime setting key should be deleted")
+	}
+}
+
+func TestResetRuntimeLogConfig_InvalidOperator(t *testing.T) {
+	svc := &OpsService{settingRepo: newRuntimeSettingRepoStub()}
+	_, err := svc.ResetRuntimeLogConfig(context.Background(), 0)
+	if err == nil {
+		t.Fatalf("expected invalid operator error")
+	}
+	if err.Error() != "invalid operator id" {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestGetRuntimeLogConfig_InvalidJSONFallback(t *testing.T) {
+	repo := newRuntimeSettingRepoStub()
+	repo.values[SettingKeyOpsRuntimeLogConfig] = `{invalid-json}`
+
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "warn",
+				Caller:          true,
+				StacktraceLevel: "error",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+		},
+	}
+
+	got, err := svc.GetRuntimeLogConfig(context.Background())
+	if err != nil {
+		t.Fatalf("GetRuntimeLogConfig() error: %v", err)
+	}
+	if got.Level != "warn" {
+		t.Fatalf("level = %q, want warn", got.Level)
+	}
+}
+
+func TestUpdateRuntimeLogConfig_PersistFailureRollback(t *testing.T) {
+	repo := newRuntimeSettingRepoStub()
+	oldCfg := &OpsRuntimeLogConfig{
+		Level:           "info",
+		EnableSampling:  false,
+		SamplingInitial: 100,
+		SamplingNext:    100,
+		Caller:          true,
+		StacktraceLevel: "error",
+		RetentionDays:   30,
+	}
+	raw, _ := json.Marshal(oldCfg)
+	repo.values[SettingKeyOpsRuntimeLogConfig] = string(raw)
+	repo.setFn = func(key, value string) error {
+		if key == SettingKeyOpsRuntimeLogConfig {
+			return errors.New("db down")
+		}
+		return nil
+	}
+
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "info",
+				Caller:          true,
+				StacktraceLevel: "error",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+		},
+	}
+
+	if err := logger.Init(logger.InitOptions{
+		Level:       "info",
+		Format:      "json",
+		ServiceName: "sub2api",
+		Environment: "test",
+		Output: logger.OutputOptions{
+			ToStdout: true,
+			ToFile:   false,
+		},
+	}); err != nil {
+		t.Fatalf("init logger: %v", err)
+	}
+
+	_, err := svc.UpdateRuntimeLogConfig(context.Background(), &OpsRuntimeLogConfig{
+		Level:           "debug",
+		EnableSampling:  false,
+		SamplingInitial: 100,
+		SamplingNext:    100,
+		Caller:          true,
+		StacktraceLevel: "error",
+		RetentionDays:   30,
+	}, 5)
+	if err == nil {
+		t.Fatalf("expected persist error")
+	}
+	// Persist failure should rollback runtime level back to old effective level.
+	if logger.CurrentLevel() != "info" {
+		t.Fatalf("logger level should rollback to info, got %s", logger.CurrentLevel())
+	}
+}
+
+func TestApplyRuntimeLogConfigOnStartup(t *testing.T) {
+	repo := newRuntimeSettingRepoStub()
+	cfgRaw := `{"level":"debug","enable_sampling":false,"sampling_initial":100,"sampling_thereafter":100,"caller":true,"stacktrace_level":"error","retention_days":30}`
+	repo.values[SettingKeyOpsRuntimeLogConfig] = cfgRaw
+
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "info",
+				Caller:          true,
+				StacktraceLevel: "error",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+		},
+	}
+
+	if err := logger.Init(logger.InitOptions{
+		Level:       "info",
+		Format:      "json",
+		ServiceName: "sub2api",
+		Environment: "test",
+		Output: logger.OutputOptions{
+			ToStdout: true,
+			ToFile:   false,
+		},
+	}); err != nil {
+		t.Fatalf("init logger: %v", err)
+	}
+
+	svc.applyRuntimeLogConfigOnStartup(context.Background())
+	if logger.CurrentLevel() != "debug" {
+		t.Fatalf("expected startup apply debug, got %s", logger.CurrentLevel())
+	}
+}
+
+func TestDefaultNormalizeAndValidateRuntimeLogConfig(t *testing.T) {
+	defaults := defaultOpsRuntimeLogConfig(&config.Config{
+		Log: config.LogConfig{
+			Level:           "DEBUG",
+			Caller:          false,
+			StacktraceLevel: "FATAL",
+			Sampling: config.LogSamplingConfig{
+				Enabled:    true,
+				Initial:    50,
+				Thereafter: 20,
+			},
+		},
+		Ops: config.OpsConfig{
+			Cleanup: config.OpsCleanupConfig{
+				ErrorLogRetentionDays: 7,
+			},
+		},
+	})
+	if defaults.Level != "debug" || defaults.StacktraceLevel != "fatal" || defaults.RetentionDays != 7 {
+		t.Fatalf("unexpected defaults: %+v", defaults)
+	}
+
+	cfg := &OpsRuntimeLogConfig{
+		Level:           " ",
+		EnableSampling:  true,
+		SamplingInitial: 0,
+		SamplingNext:    -1,
+		Caller:          true,
+		StacktraceLevel: "",
+		RetentionDays:   0,
+	}
+	normalizeOpsRuntimeLogConfig(cfg, defaults)
+	if cfg.Level != "debug" || cfg.StacktraceLevel != "fatal" {
+		t.Fatalf("normalize level/stacktrace failed: %+v", cfg)
+	}
+	if cfg.SamplingInitial != 50 || cfg.SamplingNext != 20 || cfg.RetentionDays != 7 {
+		t.Fatalf("normalize numeric defaults failed: %+v", cfg)
+	}
+	if err := validateOpsRuntimeLogConfig(cfg); err != nil {
+		t.Fatalf("validate normalized config should pass: %v", err)
+	}
+}
+
+func TestValidateRuntimeLogConfigErrors(t *testing.T) {
+	cases := []struct {
+		name string
+		cfg  *OpsRuntimeLogConfig
+	}{
+		{name: "nil", cfg: nil},
+		{name: "bad level", cfg: &OpsRuntimeLogConfig{Level: "trace", StacktraceLevel: "error", SamplingInitial: 1, SamplingNext: 1, RetentionDays: 1}},
+		{name: "bad stack", cfg: &OpsRuntimeLogConfig{Level: "info", StacktraceLevel: "warn", SamplingInitial: 1, SamplingNext: 1, RetentionDays: 1}},
+		{name: "bad initial", cfg: &OpsRuntimeLogConfig{Level: "info", StacktraceLevel: "error", SamplingInitial: 0, SamplingNext: 1, RetentionDays: 1}},
+		{name: "bad next", cfg: &OpsRuntimeLogConfig{Level: "info", StacktraceLevel: "error", SamplingInitial: 1, SamplingNext: 0, RetentionDays: 1}},
+		{name: "bad retention", cfg: &OpsRuntimeLogConfig{Level: "info", StacktraceLevel: "error", SamplingInitial: 1, SamplingNext: 1, RetentionDays: 0}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if err := validateOpsRuntimeLogConfig(tc.cfg); err == nil {
+				t.Fatalf("expected validation error")
+			}
+		})
+	}
+}
+
+func TestGetRuntimeLogConfigFallbackAndErrors(t *testing.T) {
+	var nilSvc *OpsService
+	cfg, err := nilSvc.GetRuntimeLogConfig(context.Background())
+	if err != nil {
+		t.Fatalf("nil svc should fallback default: %v", err)
+	}
+	if cfg.Level != "info" {
+		t.Fatalf("unexpected nil svc default level: %s", cfg.Level)
+	}
+
+	repo := newRuntimeSettingRepoStub()
+	repo.getValueFn = func(key string) (string, error) {
+		return "", errors.New("boom")
+	}
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "warn",
+				Caller:          true,
+				StacktraceLevel: "error",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+		},
+	}
+	if _, err := svc.GetRuntimeLogConfig(context.Background()); err == nil {
+		t.Fatalf("expected get value error")
+	}
+}
+
+func TestUpdateRuntimeLogConfig_PreconditionErrors(t *testing.T) {
+	svc := &OpsService{}
+	if _, err := svc.UpdateRuntimeLogConfig(context.Background(), &OpsRuntimeLogConfig{}, 1); err == nil {
+		t.Fatalf("expected setting repo not initialized")
+	}
+
+	svc = &OpsService{settingRepo: newRuntimeSettingRepoStub()}
+	if _, err := svc.UpdateRuntimeLogConfig(context.Background(), nil, 1); err == nil {
+		t.Fatalf("expected invalid config")
+	}
+	if _, err := svc.UpdateRuntimeLogConfig(context.Background(), &OpsRuntimeLogConfig{
+		Level:           "info",
+		StacktraceLevel: "error",
+		SamplingInitial: 1,
+		SamplingNext:    1,
+		RetentionDays:   1,
+	}, 0); err == nil {
+		t.Fatalf("expected invalid operator")
+	}
+}
+
+func TestUpdateRuntimeLogConfig_Success(t *testing.T) {
+	repo := newRuntimeSettingRepoStub()
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "info",
+				Caller:          true,
+				StacktraceLevel: "error",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+		},
+	}
+
+	if err := logger.Init(logger.InitOptions{
+		Level:       "info",
+		Format:      "json",
+		ServiceName: "sub2api",
+		Environment: "test",
+		Output: logger.OutputOptions{
+			ToStdout: true,
+			ToFile:   false,
+		},
+	}); err != nil {
+		t.Fatalf("init logger: %v", err)
+	}
+
+	next, err := svc.UpdateRuntimeLogConfig(context.Background(), &OpsRuntimeLogConfig{
+		Level:           "debug",
+		EnableSampling:  false,
+		SamplingInitial: 100,
+		SamplingNext:    100,
+		Caller:          true,
+		StacktraceLevel: "error",
+		RetentionDays:   30,
+	}, 2)
+	if err != nil {
+		t.Fatalf("UpdateRuntimeLogConfig() error: %v", err)
+	}
+	if next.Source != "runtime_setting" || next.UpdatedByUserID != 2 || next.UpdatedAt == "" {
+		t.Fatalf("unexpected metadata: %+v", next)
+	}
+	if logger.CurrentLevel() != "debug" {
+		t.Fatalf("expected applied level debug, got %s", logger.CurrentLevel())
+	}
+}
+
+func TestResetRuntimeLogConfig_IgnoreNotFoundDelete(t *testing.T) {
+	repo := newRuntimeSettingRepoStub()
+	repo.deleteFn = func(key string) error { return ErrSettingNotFound }
+	svc := &OpsService{
+		settingRepo: repo,
+		cfg: &config.Config{
+			Log: config.LogConfig{
+				Level:           "info",
+				Caller:          true,
+				StacktraceLevel: "error",
+				Sampling: config.LogSamplingConfig{
+					Enabled:    false,
+					Initial:    100,
+					Thereafter: 100,
+				},
+			},
+		},
+	}
+	if _, err := svc.ResetRuntimeLogConfig(context.Background(), 1); err != nil {
+		t.Fatalf("reset should ignore ErrSettingNotFound: %v", err)
+	}
+}
+
+func TestApplyRuntimeLogConfigHelpers(t *testing.T) {
+	if err := applyOpsRuntimeLogConfig(nil); err == nil {
+		t.Fatalf("expected nil config error")
+	}
+
+	normalizeOpsRuntimeLogConfig(nil, &OpsRuntimeLogConfig{Level: "info"})
+	normalizeOpsRuntimeLogConfig(&OpsRuntimeLogConfig{Level: "debug"}, nil)
+
+	var nilSvc *OpsService
+	nilSvc.applyRuntimeLogConfigOnStartup(context.Background())
+}
diff --git a/backend/internal/service/ops_settings_models.go b/backend/internal/service/ops_settings_models.go
index ecc62220..8b5359e3 100644
--- a/backend/internal/service/ops_settings_models.go
+++ b/backend/internal/service/ops_settings_models.go
@@ -68,6 +68,20 @@ type OpsMetricThresholds struct {
 	UpstreamErrorRatePercentMax *float64 `json:"upstream_error_rate_percent_max,omitempty"` // 上游错误率高于此值变红
 }
 
+type OpsRuntimeLogConfig struct {
+	Level           string         `json:"level"`
+	EnableSampling  bool           `json:"enable_sampling"`
+	SamplingInitial int            `json:"sampling_initial"`
+	SamplingNext    int            `json:"sampling_thereafter"`
+	Caller          bool           `json:"caller"`
+	StacktraceLevel string         `json:"stacktrace_level"`
+	RetentionDays   int            `json:"retention_days"`
+	Source          string         `json:"source,omitempty"`
+	UpdatedAt       string         `json:"updated_at,omitempty"`
+	UpdatedByUserID int64          `json:"updated_by_user_id,omitempty"`
+	Extra           map[string]any `json:"extra,omitempty"`
+}
+
 type OpsAlertRuntimeSettings struct {
 	EvaluationIntervalSeconds int `json:"evaluation_interval_seconds"`
 
diff --git a/backend/internal/service/ops_system_log_service_test.go b/backend/internal/service/ops_system_log_service_test.go
new file mode 100644
index 00000000..cc9ddefe
--- /dev/null
+++ b/backend/internal/service/ops_system_log_service_test.go
@@ -0,0 +1,243 @@
+package service
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+)
+
+func TestOpsServiceListSystemLogs_DefaultClampAndSuccess(t *testing.T) {
+	var gotFilter *OpsSystemLogFilter
+	repo := &opsRepoMock{
+		ListSystemLogsFn: func(ctx context.Context, filter *OpsSystemLogFilter) (*OpsSystemLogList, error) {
+			gotFilter = filter
+			return &OpsSystemLogList{
+				Logs:     []*OpsSystemLog{{ID: 1, Level: "warn", Message: "x"}},
+				Total:    1,
+				Page:     filter.Page,
+				PageSize: filter.PageSize,
+			}, nil
+		},
+	}
+	svc := NewOpsService(repo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+
+	out, err := svc.ListSystemLogs(context.Background(), &OpsSystemLogFilter{
+		Page:     0,
+		PageSize: 999,
+	})
+	if err != nil {
+		t.Fatalf("ListSystemLogs() error: %v", err)
+	}
+	if gotFilter == nil {
+		t.Fatalf("expected repository to receive filter")
+	}
+	if gotFilter.Page != 1 || gotFilter.PageSize != 200 {
+		t.Fatalf("filter normalized unexpectedly: page=%d pageSize=%d", gotFilter.Page, gotFilter.PageSize)
+	}
+	if out.Total != 1 || len(out.Logs) != 1 {
+		t.Fatalf("unexpected result: %+v", out)
+	}
+}
+
+func TestOpsServiceListSystemLogs_MonitoringDisabled(t *testing.T) {
+	svc := NewOpsService(
+		&opsRepoMock{},
+		nil,
+		&config.Config{Ops: config.OpsConfig{Enabled: false}},
+		nil, nil, nil, nil, nil, nil, nil, nil,
+	)
+	_, err := svc.ListSystemLogs(context.Background(), &OpsSystemLogFilter{})
+	if err == nil {
+		t.Fatalf("expected disabled error")
+	}
+}
+
+func TestOpsServiceListSystemLogs_NilRepoReturnsEmpty(t *testing.T) {
+	svc := NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	out, err := svc.ListSystemLogs(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("ListSystemLogs() error: %v", err)
+	}
+	if out == nil || out.Page != 1 || out.PageSize != 50 || out.Total != 0 || len(out.Logs) != 0 {
+		t.Fatalf("unexpected nil-repo result: %+v", out)
+	}
+}
+
+func TestOpsServiceListSystemLogs_RepoErrorMapped(t *testing.T) {
+	repo := &opsRepoMock{
+		ListSystemLogsFn: func(ctx context.Context, filter *OpsSystemLogFilter) (*OpsSystemLogList, error) {
+			return nil, errors.New("db down")
+		},
+	}
+	svc := NewOpsService(repo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	_, err := svc.ListSystemLogs(context.Background(), &OpsSystemLogFilter{})
+	if err == nil {
+		t.Fatalf("expected mapped internal error")
+	}
+	if !strings.Contains(err.Error(), "OPS_SYSTEM_LOG_LIST_FAILED") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestOpsServiceCleanupSystemLogs_SuccessAndAudit(t *testing.T) {
+	var audit *OpsSystemLogCleanupAudit
+	repo := &opsRepoMock{
+		DeleteSystemLogsFn: func(ctx context.Context, filter *OpsSystemLogCleanupFilter) (int64, error) {
+			return 3, nil
+		},
+		InsertSystemLogCleanupAuditFn: func(ctx context.Context, input *OpsSystemLogCleanupAudit) error {
+			audit = input
+			return nil
+		},
+	}
+	svc := NewOpsService(repo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	userID := int64(7)
+	now := time.Now().UTC()
+	filter := &OpsSystemLogCleanupFilter{
+		StartTime:       &now,
+		Level:           "warn",
+		RequestID:       "req-1",
+		ClientRequestID: "creq-1",
+		UserID:          &userID,
+		Query:           "timeout",
+	}
+
+	deleted, err := svc.CleanupSystemLogs(context.Background(), filter, 99)
+	if err != nil {
+		t.Fatalf("CleanupSystemLogs() error: %v", err)
+	}
+	if deleted != 3 {
+		t.Fatalf("deleted=%d, want 3", deleted)
+	}
+	if audit == nil {
+		t.Fatalf("expected cleanup audit")
+	}
+	if !strings.Contains(audit.Conditions, `"client_request_id":"creq-1"`) {
+		t.Fatalf("audit conditions should include client_request_id: %s", audit.Conditions)
+	}
+	if !strings.Contains(audit.Conditions, `"user_id":7`) {
+		t.Fatalf("audit conditions should include user_id: %s", audit.Conditions)
+	}
+}
+
+func TestOpsServiceCleanupSystemLogs_RepoUnavailableAndInvalidOperator(t *testing.T) {
+	svc := NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	if _, err := svc.CleanupSystemLogs(context.Background(), &OpsSystemLogCleanupFilter{RequestID: "r"}, 1); err == nil {
+		t.Fatalf("expected repo unavailable error")
+	}
+
+	svc = NewOpsService(&opsRepoMock{}, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	if _, err := svc.CleanupSystemLogs(context.Background(), &OpsSystemLogCleanupFilter{RequestID: "r"}, 0); err == nil {
+		t.Fatalf("expected invalid operator error")
+	}
+}
+
+func TestOpsServiceCleanupSystemLogs_FilterRequired(t *testing.T) {
+	repo := &opsRepoMock{
+		DeleteSystemLogsFn: func(ctx context.Context, filter *OpsSystemLogCleanupFilter) (int64, error) {
+			return 0, errors.New("cleanup requires at least one filter condition")
+		},
+	}
+	svc := NewOpsService(repo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	_, err := svc.CleanupSystemLogs(context.Background(), &OpsSystemLogCleanupFilter{}, 1)
+	if err == nil {
+		t.Fatalf("expected filter required error")
+	}
+	if !strings.Contains(strings.ToLower(err.Error()), "filter") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestOpsServiceCleanupSystemLogs_InvalidRange(t *testing.T) {
+	repo := &opsRepoMock{}
+	svc := NewOpsService(repo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	start := time.Now().UTC()
+	end := start.Add(-time.Hour)
+	_, err := svc.CleanupSystemLogs(context.Background(), &OpsSystemLogCleanupFilter{
+		StartTime: &start,
+		EndTime:   &end,
+	}, 1)
+	if err == nil {
+		t.Fatalf("expected invalid range error")
+	}
+}
+
+func TestOpsServiceCleanupSystemLogs_NoRowsAndInternalError(t *testing.T) {
+	repo := &opsRepoMock{
+		DeleteSystemLogsFn: func(ctx context.Context, filter *OpsSystemLogCleanupFilter) (int64, error) {
+			return 0, sql.ErrNoRows
+		},
+	}
+	svc := NewOpsService(repo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	deleted, err := svc.CleanupSystemLogs(context.Background(), &OpsSystemLogCleanupFilter{
+		RequestID: "req-1",
+	}, 1)
+	if err != nil || deleted != 0 {
+		t.Fatalf("expected no rows shortcut, deleted=%d err=%v", deleted, err)
+	}
+
+	repo.DeleteSystemLogsFn = func(ctx context.Context, filter *OpsSystemLogCleanupFilter) (int64, error) {
+		return 0, errors.New("boom")
+	}
+	if _, err := svc.CleanupSystemLogs(context.Background(), &OpsSystemLogCleanupFilter{
+		RequestID: "req-1",
+	}, 1); err == nil {
+		t.Fatalf("expected internal cleanup error")
+	}
+}
+
+func TestOpsServiceCleanupSystemLogs_AuditFailureIgnored(t *testing.T) {
+	repo := &opsRepoMock{
+		DeleteSystemLogsFn: func(ctx context.Context, filter *OpsSystemLogCleanupFilter) (int64, error) {
+			return 5, nil
+		},
+		InsertSystemLogCleanupAuditFn: func(ctx context.Context, input *OpsSystemLogCleanupAudit) error {
+			return errors.New("audit down")
+		},
+	}
+	svc := NewOpsService(repo, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	deleted, err := svc.CleanupSystemLogs(context.Background(), &OpsSystemLogCleanupFilter{
+		RequestID: "r1",
+	}, 1)
+	if err != nil || deleted != 5 {
+		t.Fatalf("audit failure should not break cleanup, deleted=%d err=%v", deleted, err)
+	}
+}
+
+func TestMarshalSystemLogCleanupConditions_NilAndMarshalError(t *testing.T) {
+	if got := marshalSystemLogCleanupConditions(nil); got != "{}" {
+		t.Fatalf("nil filter should return {}, got %s", got)
+	}
+
+	now := time.Now().UTC()
+	userID := int64(1)
+	filter := &OpsSystemLogCleanupFilter{
+		StartTime: &now,
+		EndTime:   &now,
+		UserID:    &userID,
+	}
+	got := marshalSystemLogCleanupConditions(filter)
+	if !strings.Contains(got, `"start_time"`) || !strings.Contains(got, `"user_id":1`) {
+		t.Fatalf("unexpected marshal payload: %s", got)
+	}
+}
+
+func TestOpsServiceGetSystemLogSinkHealth(t *testing.T) {
+	svc := NewOpsService(nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	health := svc.GetSystemLogSinkHealth()
+	if health.QueueCapacity != 0 || health.QueueDepth != 0 {
+		t.Fatalf("unexpected health for nil sink: %+v", health)
+	}
+
+	sink := NewOpsSystemLogSink(&opsRepoMock{})
+	svc = NewOpsService(&opsRepoMock{}, nil, nil, nil, nil, nil, nil, nil, nil, nil, sink)
+	health = svc.GetSystemLogSinkHealth()
+	if health.QueueCapacity <= 0 {
+		t.Fatalf("expected non-zero queue capacity: %+v", health)
+	}
+}