feat: 解决 CDC 去重、集中备份与首次初始化问题 (#105)

实现 CDC 内容寻址仓库、远程 Agent 中央中转备份与首次初始化体验，并补充安全校验、测试及双语文档。 Closes #94 Closes #101 Closes #104
2026-08-11 23:53:25 +08:00 · 2026-08-07 23:01:29 +08:00
parent 50ce6587d8
commit 00151e466c
74 changed files with 4507 additions and 400 deletions
--- a/server/internal/agent/client.go
+++ b/server/internal/agent/client.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"crypto/tls"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -125,10 +126,11 @@ type TaskSpec struct {

 // StorageTargetConfig 与 service.AgentStorageTargetConfig 对齐
 type StorageTargetConfig struct {
-	ID     uint            `json:"id"`
-	Type   string          `json:"type"`
-	Name   string          `json:"name"`
-	Config json.RawMessage `json:"config"`
+	ID           uint            `json:"id"`
+	Type         string          `json:"type"`
+	Name         string          `json:"name"`
+	Config       json.RawMessage `json:"config"`
+	TransferMode string          `json:"transferMode"`
 }

 // GetTaskSpec 拉取任务规格
@@ -149,6 +151,7 @@ type RecordUpdate struct {
 	Checksum             string              `json:"checksum,omitempty"`
 	StoragePath          string              `json:"storagePath,omitempty"`
 	StorageTargetID      uint                `json:"storageTargetId,omitempty"`
+	StorageTransferMode  string              `json:"storageTransferMode,omitempty"`
 	StorageUploadResults []StorageResultItem `json:"storageUploadResults,omitempty"`
 	ErrorMessage         string              `json:"errorMessage,omitempty"`
 	LogAppend            string              `json:"logAppend,omitempty"`
@@ -160,6 +163,7 @@ type StorageResultItem struct {
 	Status            string `json:"status"`
 	StoragePath       string `json:"storagePath,omitempty"`
 	FileSize          int64  `json:"fileSize,omitempty"`
+	TransferMode      string `json:"transferMode,omitempty"`
 	Error             string `json:"error,omitempty"`
 }

@@ -169,6 +173,39 @@ func (c *MasterClient) UpdateRecord(ctx context.Context, recordID uint, update R
 	return c.do(ctx, http.MethodPost, path, update, nil)
 }

+// UploadArtifact streams an artifact through the Master for storage targets
+// that are not directly reachable from the Agent.
+func (c *MasterClient) UploadArtifact(ctx context.Context, recordID, targetID uint, objectKey string, size int64, checksum string, reader io.Reader) error {
+	path := fmt.Sprintf("/api/agent/records/%d/artifacts/%d", recordID, targetID)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPut, c.baseURL+path, reader)
+	if err != nil {
+		return err
+	}
+	// The executor owns and closes the artifact file. Prevent net/http from
+	// closing that underlying reader when it finishes the request body.
+	req.Body = io.NopCloser(reader)
+	req.ContentLength = size
+	req.Header.Set("Content-Type", "application/octet-stream")
+	req.Header.Set("X-Agent-Token", c.token)
+	req.Header.Set("X-BackupX-Object-Key", objectKey)
+	req.Header.Set("X-BackupX-SHA256", checksum)
+	client := *c.httpClient
+	client.Timeout = 0
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("relay artifact to Master: %w", err)
+	}
+	data, readErr := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	closeErr := resp.Body.Close()
+	if readErr != nil || closeErr != nil {
+		return errors.Join(readErr, closeErr)
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return fmt.Errorf("relay artifact to Master: http %d: %s", resp.StatusCode, string(data))
+	}
+	return nil
+}
+
 // RestoreSpec 与 service.AgentRestoreSpec 对齐
 type RestoreSpec struct {
 	RestoreRecordID uint                `json:"restoreRecordId"`
@@ -210,6 +247,27 @@ func (c *MasterClient) GetRestoreSpec(ctx context.Context, restoreRecordID uint)
 	return &spec, nil
 }

+func (c *MasterClient) DownloadRestoreArtifact(ctx context.Context, restoreRecordID uint) (io.ReadCloser, error) {
+	path := fmt.Sprintf("/api/agent/restores/%d/artifact", restoreRecordID)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+path, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("X-Agent-Token", c.token)
+	client := *c.httpClient
+	client.Timeout = 0
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("download relayed artifact from Master: %w", err)
+	}
+	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+		return resp.Body, nil
+	}
+	data, readErr := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	closeErr := resp.Body.Close()
+	return nil, errors.Join(fmt.Errorf("download relayed artifact from Master: http %d: %s", resp.StatusCode, string(data)), readErr, closeErr)
+}
+
 // UpdateRestore 上报恢复记录的状态/日志
 func (c *MasterClient) UpdateRestore(ctx context.Context, restoreRecordID uint, update RestoreUpdate) error {
 	path := fmt.Sprintf("/api/agent/restores/%d", restoreRecordID)
--- a/server/internal/agent/executor.go
+++ b/server/internal/agent/executor.go
@@ -5,6 +5,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -123,7 +124,7 @@ func (e *Executor) ExecuteRunTask(ctx context.Context, taskID, recordID uint) er
 	}
 	fileName := filepath.Base(finalPath)
 	fileSize := info.Size()
-	storagePath := backup.BuildStorageKey(spec.Type, startedAt, fileName)
+	storagePath := backup.BuildRecordStorageKey(spec.Type, startedAt, recordID, fileName)

 	// 5) 计算 checksum（一次读一次）并上传到所有目标
 	checksum, err := computeFileSHA256(finalPath)
@@ -137,13 +138,15 @@ func (e *Executor) ExecuteRunTask(ctx context.Context, taskID, recordID uint) er
 	}
 	uploadResults := make([]StorageResultItem, 0, len(spec.StorageTargets))
 	selectedStorageTargetID := uint(0)
+	selectedStorageTransferMode := ""
 	var uploadErrors []string
 	for _, target := range spec.StorageTargets {
-		if err := e.uploadToTarget(ctx, recordID, target, finalPath, storagePath, fileSize, spec.TaskID); err != nil {
+		if err := e.uploadToTarget(ctx, recordID, target, finalPath, storagePath, fileSize, checksum, spec.TaskID); err != nil {
 			uploadResults = append(uploadResults, StorageResultItem{
 				StorageTargetID:   target.ID,
 				StorageTargetName: target.Name,
 				Status:            "failed",
+				TransferMode:      target.TransferMode,
 				Error:             err.Error(),
 			})
 			uploadErrors = append(uploadErrors, fmt.Sprintf("%s: %v", target.Name, err))
@@ -152,6 +155,7 @@ func (e *Executor) ExecuteRunTask(ctx context.Context, taskID, recordID uint) er
 		}
 		if selectedStorageTargetID == 0 {
 			selectedStorageTargetID = target.ID
+			selectedStorageTransferMode = target.TransferMode
 		}
 		uploadResults = append(uploadResults, StorageResultItem{
 			StorageTargetID:   target.ID,
@@ -159,6 +163,7 @@ func (e *Executor) ExecuteRunTask(ctx context.Context, taskID, recordID uint) er
 			Status:            "success",
 			StoragePath:       storagePath,
 			FileSize:          fileSize,
+			TransferMode:      target.TransferMode,
 		})
 		e.appendLog(ctx, recordID, fmt.Sprintf("[agent] 已上传到存储目标 %s\n", target.Name))
 	}
@@ -179,34 +184,40 @@ func (e *Executor) ExecuteRunTask(ctx context.Context, taskID, recordID uint) er
 		Checksum:             checksum,
 		StoragePath:          storagePath,
 		StorageTargetID:      selectedStorageTargetID,
+		StorageTransferMode:  selectedStorageTransferMode,
 		StorageUploadResults: uploadResults,
 		LogAppend:            fmt.Sprintf("[agent] 任务完成，总计 %d 字节\n", fileSize),
 	})
 }

 // uploadToTarget 上传单个目标。为保持简化不做上传级重试（rclone 本身已有 low-level 重试）。
-func (e *Executor) uploadToTarget(ctx context.Context, recordID uint, target StorageTargetConfig, filePath, objectKey string, fileSize int64, taskID uint) error {
-	var rawConfig map[string]any
-	if len(target.Config) > 0 {
-		// DecodeRawConfig 通过 json 解析
-		if err := jsonUnmarshalMap(target.Config, &rawConfig); err != nil {
-			return fmt.Errorf("parse storage config: %w", err)
-		}
-	}
-	provider, err := e.storageRegistry.Create(ctx, target.Type, rawConfig)
-	if err != nil {
-		return fmt.Errorf("create provider: %w", err)
-	}
+func (e *Executor) uploadToTarget(ctx context.Context, recordID uint, target StorageTargetConfig, filePath, objectKey string, fileSize int64, checksum string, taskID uint) error {
 	f, err := os.Open(filePath)
 	if err != nil {
 		return fmt.Errorf("open artifact: %w", err)
 	}
-	defer f.Close()
+	if target.TransferMode == storage.TransferModeMasterRelay {
+		uploadErr := e.client.UploadArtifact(ctx, recordID, target.ID, objectKey, fileSize, checksum, f)
+		return errors.Join(uploadErr, f.Close())
+	}
+	var rawConfig map[string]any
+	if len(target.Config) > 0 {
+		// DecodeRawConfig 通过 json 解析
+		if err := jsonUnmarshalMap(target.Config, &rawConfig); err != nil {
+			return errors.Join(fmt.Errorf("parse storage config: %w", err), f.Close())
+		}
+	}
+	provider, err := e.storageRegistry.Create(ctx, target.Type, rawConfig)
+	if err != nil {
+		closeErr := f.Close()
+		return errors.Join(fmt.Errorf("create provider: %w", err), closeErr)
+	}
 	meta := map[string]string{
 		"taskId":   fmt.Sprintf("%d", taskID),
 		"recordId": fmt.Sprintf("%d", recordID),
 	}
-	return provider.Upload(ctx, objectKey, f, fileSize, meta)
+	uploadErr := provider.Upload(ctx, objectKey, f, fileSize, meta)
+	return errors.Join(uploadErr, f.Close())
 }

 // appendLog 追加日志到 Master 记录（尽力而为，失败不中断主流程）
@@ -328,7 +339,7 @@ func (e *Executor) DeleteStorageObject(ctx context.Context, targetType string, t
 // ExecuteRestore 处理 restore_record 命令：拉规格 → 下载 → 解压 → 执行 runner.Restore → 上报结果。
 //
 // 与 ExecuteRunTask 对称，但方向相反：
-//   - 下载：通过 spec.Storage 创建 provider → Download(spec.StoragePath)
+//   - 下载：直连共享存储，或通过 Master 中转其本地磁盘对象
 //   - 解密：当前 Agent 不支持加密恢复（密钥未下发），spec.Encrypt=true 会直接失败
 //   - 执行：backup.Registry.Runner(spec.Type).Restore
 //   - 上报：通过 UpdateRestore（status/logAppend）
@@ -357,28 +368,31 @@ func (e *Executor) ExecuteRestore(ctx context.Context, restoreRecordID uint) err
 	}
 	defer os.RemoveAll(tmpDir)

-	// 1) 创建 storage provider
-	var rawConfig map[string]any
-	if len(spec.Storage.Config) > 0 {
-		if err := jsonUnmarshalMap(spec.Storage.Config, &rawConfig); err != nil {
-			e.reportRestoreFailure(ctx, restoreRecordID, fmt.Sprintf("解析存储配置失败: %v", err))
-			return err
-		}
-	}
-	provider, err := e.storageRegistry.Create(ctx, spec.Storage.Type, rawConfig)
-	if err != nil {
-		e.reportRestoreFailure(ctx, restoreRecordID, fmt.Sprintf("创建存储客户端失败: %v", err))
-		return err
-	}
-
-	// 2) 下载
+	// 1) 下载
 	fileName := spec.FileName
 	if strings.TrimSpace(fileName) == "" {
 		fileName = filepath.Base(spec.StoragePath)
 	}
 	artifactPath := filepath.Join(tmpDir, filepath.Base(fileName))
 	e.appendRestoreLog(ctx, restoreRecordID, fmt.Sprintf("[agent] 下载备份文件 %s\n", spec.StoragePath))
-	reader, err := provider.Download(ctx, spec.StoragePath)
+	var reader io.ReadCloser
+	if spec.Storage.TransferMode == storage.TransferModeMasterRelay {
+		reader, err = e.client.DownloadRestoreArtifact(ctx, restoreRecordID)
+	} else {
+		var rawConfig map[string]any
+		if len(spec.Storage.Config) > 0 {
+			if err := jsonUnmarshalMap(spec.Storage.Config, &rawConfig); err != nil {
+				e.reportRestoreFailure(ctx, restoreRecordID, fmt.Sprintf("解析存储配置失败: %v", err))
+				return err
+			}
+		}
+		provider, providerErr := e.storageRegistry.Create(ctx, spec.Storage.Type, rawConfig)
+		if providerErr != nil {
+			e.reportRestoreFailure(ctx, restoreRecordID, fmt.Sprintf("创建存储客户端失败: %v", providerErr))
+			return providerErr
+		}
+		reader, err = provider.Download(ctx, spec.StoragePath)
+	}
 	if err != nil {
 		e.reportRestoreFailure(ctx, restoreRecordID, fmt.Sprintf("下载备份失败: %v", err))
 		return err
@@ -489,8 +503,10 @@ func buildRestoreBackupTaskSpec(spec *RestoreSpec, startedAt time.Time, tempDir
 }

 // writeReaderToLocal 把 reader 写到本地文件（Agent 侧工具函数）。
-func writeReaderToLocal(targetPath string, reader io.ReadCloser) error {
-	defer reader.Close()
+func writeReaderToLocal(targetPath string, reader io.ReadCloser) (err error) {
+	defer func() {
+		err = errors.Join(err, reader.Close())
+	}()
 	if err := os.MkdirAll(filepath.Dir(targetPath), 0o755); err != nil {
 		return err
 	}
@@ -498,9 +514,8 @@ func writeReaderToLocal(targetPath string, reader io.ReadCloser) error {
 	if err != nil {
 		return err
 	}
-	defer file.Close()
-	_, err = io.Copy(file, reader)
-	return err
+	_, copyErr := io.Copy(file, reader)
+	return errors.Join(copyErr, file.Close())
 }

 // 辅助函数
--- a/server/internal/agent/executor_test.go
+++ b/server/internal/agent/executor_test.go
@@ -1,7 +1,10 @@
 package agent

 import (
+	"archive/tar"
+	"bytes"
 	"context"
+	"crypto/sha256"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -109,6 +112,150 @@ func TestExecuteRunTaskRecordsPerTargetUploadResults(t *testing.T) {
 	}
 }

+func TestExecuteRunTaskRelaysMasterLocalDiskTarget(t *testing.T) {
+	sourceDir := t.TempDir()
+	if err := os.WriteFile(filepath.Join(sourceDir, "index.html"), []byte("centralize me"), 0o644); err != nil {
+		t.Fatalf("WriteFile returned error: %v", err)
+	}
+	var relayed []byte
+	var finalUpdate RecordUpdate
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case r.Method == http.MethodGet && r.URL.Path == "/api/agent/tasks/1":
+			writeAgentEnvelope(t, w, TaskSpec{
+				TaskID:      1,
+				Name:        "remote-source",
+				Type:        "file",
+				SourcePath:  sourceDir,
+				Compression: "gzip",
+				StorageTargets: []StorageTargetConfig{{
+					ID: 11, Name: "master-disk", Type: storage.TypeLocalDisk, TransferMode: storage.TransferModeMasterRelay,
+				}},
+			})
+		case r.Method == http.MethodPut && r.URL.Path == "/api/agent/records/99/artifacts/11":
+			body, err := io.ReadAll(r.Body)
+			if err != nil {
+				t.Fatalf("ReadAll relayed body: %v", err)
+			}
+			digest := sha256.Sum256(body)
+			if got := r.Header.Get("X-BackupX-SHA256"); got != fmt.Sprintf("%x", digest[:]) {
+				t.Fatalf("relay checksum header = %q", got)
+			}
+			objectKey := r.Header.Get("X-BackupX-Object-Key")
+			if !strings.Contains(objectKey, "/records/99/") || r.ContentLength != int64(len(body)) {
+				t.Fatalf("invalid relay metadata: key=%q length=%d body=%d", objectKey, r.ContentLength, len(body))
+			}
+			relayed = append([]byte(nil), body...)
+			writeAgentEnvelope(t, w, map[string]string{"status": "ok"})
+		case r.Method == http.MethodPost && r.URL.Path == "/api/agent/records/99":
+			var update RecordUpdate
+			if err := json.NewDecoder(r.Body).Decode(&update); err != nil {
+				t.Fatalf("Decode update returned error: %v", err)
+			}
+			if update.Status != "" {
+				finalUpdate = update
+			}
+			writeAgentEnvelope(t, w, map[string]string{"status": "ok"})
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+
+	executor := NewExecutor(NewMasterClient(server.URL, "token", false), filepath.Join(t.TempDir(), "tmp"))
+	if err := executor.ExecuteRunTask(context.Background(), 1, 99); err != nil {
+		t.Fatalf("ExecuteRunTask returned error: %v", err)
+	}
+	if len(relayed) == 0 {
+		t.Fatal("expected artifact bytes to be streamed through Master")
+	}
+	if finalUpdate.Status != "success" || finalUpdate.StorageTransferMode != storage.TransferModeMasterRelay {
+		t.Fatalf("unexpected final relay update: %#v", finalUpdate)
+	}
+	if len(finalUpdate.StorageUploadResults) != 1 || finalUpdate.StorageUploadResults[0].TransferMode != storage.TransferModeMasterRelay {
+		t.Fatalf("unexpected relay target result: %#v", finalUpdate.StorageUploadResults)
+	}
+}
+
+func TestExecuteRestoreDownloadsMasterRelayedArtifact(t *testing.T) {
+	var archive bytes.Buffer
+	tarWriter := tar.NewWriter(&archive)
+	content := []byte("restored through Master")
+	header := &tar.Header{Name: "site/index.html", Mode: 0o644, Size: int64(len(content)), Typeflag: tar.TypeReg}
+	if err := tarWriter.WriteHeader(header); err != nil {
+		t.Fatalf("WriteHeader returned error: %v", err)
+	}
+	if _, err := tarWriter.Write(content); err != nil {
+		t.Fatalf("Write returned error: %v", err)
+	}
+	if err := tarWriter.Close(); err != nil {
+		t.Fatalf("Close returned error: %v", err)
+	}
+	artifact := append([]byte(nil), archive.Bytes()...)
+	digest := sha256.Sum256(artifact)
+	restoreRoot := t.TempDir()
+	restoreSource := filepath.Join(restoreRoot, "site")
+	artifactRequests := 0
+	var finalUpdate RestoreUpdate
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case r.Method == http.MethodGet && r.URL.Path == "/api/agent/restores/77/spec":
+			writeAgentEnvelope(t, w, RestoreSpec{
+				RestoreRecordID: 77,
+				BackupRecordID:  99,
+				TaskID:          1,
+				TaskName:        "remote-source",
+				Type:            "file",
+				SourcePath:      restoreSource,
+				Storage: StorageTargetConfig{
+					ID: 11, Name: "master-disk", Type: storage.TypeLocalDisk, TransferMode: storage.TransferModeMasterRelay,
+				},
+				StoragePath: "BackupX/file/site.tar",
+				FileName:    "site.tar",
+				Checksum:    fmt.Sprintf("%x", digest[:]),
+			})
+		case r.Method == http.MethodGet && r.URL.Path == "/api/agent/restores/77/artifact":
+			artifactRequests++
+			if r.Header.Get("X-Agent-Token") != "token" {
+				t.Fatalf("missing Agent token on relay download")
+			}
+			w.Header().Set("Content-Length", fmt.Sprintf("%d", len(artifact)))
+			_, _ = w.Write(artifact)
+		case r.Method == http.MethodPost && r.URL.Path == "/api/agent/restores/77":
+			var update RestoreUpdate
+			if err := json.NewDecoder(r.Body).Decode(&update); err != nil {
+				t.Fatalf("Decode update returned error: %v", err)
+			}
+			if update.Status != "" {
+				finalUpdate = update
+			}
+			writeAgentEnvelope(t, w, map[string]string{"status": "ok"})
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+
+	executor := NewExecutor(NewMasterClient(server.URL, "token", false), filepath.Join(t.TempDir(), "tmp"))
+	if err := executor.ExecuteRestore(context.Background(), 77); err != nil {
+		t.Fatalf("ExecuteRestore returned error: %v", err)
+	}
+	if artifactRequests != 1 {
+		t.Fatalf("expected one relay artifact request, got %d", artifactRequests)
+	}
+	restored, err := os.ReadFile(filepath.Join(restoreRoot, "site", "index.html"))
+	if err != nil {
+		t.Fatalf("ReadFile returned error: %v", err)
+	}
+	if string(restored) != string(content) {
+		t.Fatalf("restored content = %q, want %q", restored, content)
+	}
+	if finalUpdate.Status != "success" {
+		t.Fatalf("unexpected final restore update: %#v", finalUpdate)
+	}
+}
+
 func TestExecuteRunTaskReportsPerTargetUploadResultsWhenAllTargetsFail(t *testing.T) {
 	sourceDir := t.TempDir()
 	if err := os.WriteFile(filepath.Join(sourceDir, "index.html"), []byte("hello"), 0o644); err != nil {
--- a/server/internal/app/app.go
+++ b/server/internal/app/app.go
@@ -84,7 +84,7 @@ func New(ctx context.Context, cfg config.Config, version string) (*Application,
 	// nodeRepo 在下方 Cluster 节点管理区块才实例化，这里延后注入
 	backupRunnerRegistry := backup.NewRegistry(backup.NewFileRunner(), backup.NewSQLiteRunner(), backup.NewMySQLRunner(nil), backup.NewPostgreSQLRunner(nil), backup.NewSAPHANARunner(nil), backup.NewMongoDBRunner(nil))
 	logHub := backup.NewLogHub()
-	retentionService := backupretention.NewService(backupRecordRepo)
+	retentionService := backupretention.NewService(backupRecordRepo, configCipher.Key())
 	notifyRegistry := notify.NewRegistry(notify.NewEmailNotifier(), notify.NewWebhookNotifier(), notify.NewTelegramNotifier())
 	notificationService := service.NewNotificationService(notificationRepo, notifyRegistry, configCipher)
 	authService.SetNotificationService(notificationService)
@@ -135,7 +135,7 @@ func New(ctx context.Context, cfg config.Config, version string) (*Application,
 	// Agent 协议服务：命令队列 + 任务下发 + 记录上报
 	agentCmdRepo := repository.NewAgentCommandRepository(db)
 	nodeService.SetAgentCommandRepository(agentCmdRepo)
-	agentService := service.NewAgentService(nodeRepo, backupTaskRepo, backupRecordRepo, storageTargetRepo, agentCmdRepo, configCipher)
+	agentService := service.NewAgentService(nodeRepo, backupTaskRepo, backupRecordRepo, storageTargetRepo, agentCmdRepo, configCipher, storageRegistry)
 	agentService.SetRestoreRepository(restoreRecordRepo)
 	agentService.StartCommandTimeoutMonitor(ctx, 30*time.Second, 10*time.Minute)

--- a/server/internal/backup/repository.go
+++ b/server/internal/backup/repository.go
--- a/server/internal/backup/repository_chunker.go
+++ b/server/internal/backup/repository_chunker.go
@@ -0,0 +1,131 @@
+package backup
+
+import (
+	"context"
+	"fmt"
+	"io"
+)
+
+const (
+	repositoryChunkMin = 512 << 10
+	repositoryChunkAvg = 1 << 20
+	repositoryChunkMax = 4 << 20
+)
+
+// contentDefinedChunker implements the normalized FastCDC cut-point strategy.
+// The rolling Gear hash only retains the latest 64 bytes through uint64
+// overflow, so chunk boundaries re-synchronize after insertions or deletions.
+type contentDefinedChunker struct {
+	minSize   int
+	avgSize   int
+	maxSize   int
+	smallMask uint64
+	largeMask uint64
+	gear      [256]uint64
+}
+
+func newContentDefinedChunker() *contentDefinedChunker {
+	chunker := &contentDefinedChunker{
+		minSize:   repositoryChunkMin,
+		avgSize:   repositoryChunkAvg,
+		maxSize:   repositoryChunkMax,
+		smallMask: (1 << 21) - 1,
+		largeMask: (1 << 19) - 1,
+	}
+
+	// SplitMix64 produces a stable, well-distributed Gear table. The seed and
+	// generation algorithm are part of repository format v1 and must not change.
+	seed := uint64(0x6a09e667f3bcc909)
+	for i := range chunker.gear {
+		seed += 0x9e3779b97f4a7c15
+		value := seed
+		value = (value ^ (value >> 30)) * 0xbf58476d1ce4e5b9
+		value = (value ^ (value >> 27)) * 0x94d049bb133111eb
+		chunker.gear[i] = value ^ (value >> 31)
+	}
+	return chunker
+}
+
+func (c *contentDefinedChunker) Split(ctx context.Context, reader io.Reader, emit func([]byte) error) error {
+	if reader == nil || emit == nil {
+		return fmt.Errorf("chunk reader and emitter are required")
+	}
+
+	pending := make([]byte, 0, c.maxSize+(256<<10))
+	readBuffer := make([]byte, 256<<10)
+	eof := false
+	for {
+		if !eof {
+			readCount, readErr := reader.Read(readBuffer)
+			if readCount > 0 {
+				pending = append(pending, readBuffer[:readCount]...)
+			}
+			switch readErr {
+			case nil:
+			case io.EOF:
+				eof = true
+			default:
+				return fmt.Errorf("read source for chunking: %w", readErr)
+			}
+			if readCount == 0 && readErr == nil {
+				continue
+			}
+		}
+
+		for len(pending) > 0 {
+			if err := ctx.Err(); err != nil {
+				return err
+			}
+			cut := c.findCutPoint(pending, eof)
+			if cut == 0 {
+				break
+			}
+			chunk := make([]byte, cut)
+			copy(chunk, pending[:cut])
+			if err := emit(chunk); err != nil {
+				return err
+			}
+			copy(pending, pending[cut:])
+			pending = pending[:len(pending)-cut]
+		}
+
+		if eof {
+			if len(pending) != 0 {
+				return fmt.Errorf("chunker stopped with %d buffered bytes", len(pending))
+			}
+			return nil
+		}
+	}
+}
+
+func (c *contentDefinedChunker) findCutPoint(data []byte, eof bool) int {
+	if len(data) < c.minSize {
+		if eof {
+			return len(data)
+		}
+		return 0
+	}
+
+	limit := len(data)
+	if limit > c.maxSize {
+		limit = c.maxSize
+	}
+	var hash uint64
+	for index := c.minSize; index < limit; index++ {
+		hash = (hash << 1) + c.gear[data[index]]
+		mask := c.largeMask
+		if index < c.avgSize {
+			mask = c.smallMask
+		}
+		if hash&mask == 0 {
+			return index + 1
+		}
+	}
+	if len(data) >= c.maxSize {
+		return c.maxSize
+	}
+	if eof {
+		return len(data)
+	}
+	return 0
+}
--- a/server/internal/backup/repository_test.go
+++ b/server/internal/backup/repository_test.go
@@ -0,0 +1,414 @@
+package backup
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"encoding/json"
+	"fmt"
+	"io"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"backupx/server/internal/storage"
+)
+
+func TestContentDefinedChunkerResynchronizesAfterInsertion(t *testing.T) {
+	source := make([]byte, 8<<20)
+	if _, err := rand.New(rand.NewSource(42)).Read(source); err != nil {
+		t.Fatalf("generate source: %v", err)
+	}
+	modified := make([]byte, 0, len(source)+4096)
+	modified = append(modified, source[:2<<20]...)
+	modified = append(modified, bytes.Repeat([]byte("inserted"), 512)...)
+	modified = append(modified, source[2<<20:]...)
+
+	chunker := newContentDefinedChunker()
+	collect := func(data []byte) map[string]struct{} {
+		t.Helper()
+		ids := make(map[string]struct{})
+		err := chunker.Split(context.Background(), bytes.NewReader(data), func(chunk []byte) error {
+			digest := sha256.Sum256(chunk)
+			ids[fmt.Sprintf("%x", digest[:])] = struct{}{}
+			if len(chunk) > repositoryChunkMax {
+				return fmt.Errorf("chunk exceeds maximum: %d", len(chunk))
+			}
+			return nil
+		})
+		if err != nil {
+			t.Fatalf("split chunks: %v", err)
+		}
+		return ids
+	}
+	originalChunks := collect(source)
+	modifiedChunks := collect(modified)
+	shared := 0
+	for chunkID := range originalChunks {
+		if _, ok := modifiedChunks[chunkID]; ok {
+			shared++
+		}
+	}
+	if shared < len(originalChunks)/2 {
+		t.Fatalf("content-defined boundaries did not resynchronize: shared=%d original=%d", shared, len(originalChunks))
+	}
+}
+
+func TestRepositoryRoundTripDedupAndPrune(t *testing.T) {
+	ctx := context.Background()
+	tempDir := t.TempDir()
+	sourceDir := filepath.Join(tempDir, "dataset")
+	if err := os.MkdirAll(filepath.Join(sourceDir, "empty"), 0o755); err != nil {
+		t.Fatalf("create source: %v", err)
+	}
+	original := make([]byte, 6<<20)
+	if _, err := rand.New(rand.NewSource(7)).Read(original); err != nil {
+		t.Fatalf("generate fixture: %v", err)
+	}
+	primaryPath := filepath.Join(sourceDir, "primary.bin")
+	duplicatePath := filepath.Join(sourceDir, "duplicate.bin")
+	if err := os.WriteFile(primaryPath, original, 0o640); err != nil {
+		t.Fatalf("write primary: %v", err)
+	}
+	if err := os.WriteFile(duplicatePath, original, 0o640); err != nil {
+		t.Fatalf("write duplicate: %v", err)
+	}
+
+	key := sha256.Sum256([]byte("repository-test-key"))
+	store := NewRepositoryStore(key[:])
+	provider := newMemoryRepositoryProvider()
+	task := TaskSpec{
+		ID:          12,
+		Name:        "repository-test",
+		Type:        "file",
+		SourcePaths: []string{sourceDir},
+		Compression: "zstd",
+		Encrypt:     true,
+		StartedAt:   time.Date(2026, 8, 6, 1, 2, 3, 0, time.UTC),
+		TempDir:     tempDir,
+	}
+
+	firstPlan, err := store.BuildPlan(ctx, task, NopLogWriter{})
+	if err != nil {
+		t.Fatalf("build first plan: %v", err)
+	}
+	firstKey := store.SnapshotKey(task.ID, 1, task.StartedAt)
+	firstResult, err := store.Upload(ctx, provider, firstPlan, firstKey)
+	if closeErr := firstPlan.Close(); closeErr != nil {
+		t.Fatalf("close first plan: %v", closeErr)
+	}
+	if err != nil {
+		t.Fatalf("upload first snapshot: %v", err)
+	}
+	if firstResult.NewChunks == 0 || firstResult.UniqueChunks == 0 {
+		t.Fatalf("first upload did not create chunks: %+v", firstResult)
+	}
+	if firstPlan.UniqueSize >= firstPlan.LogicalSize {
+		t.Fatalf("duplicate file was not deduplicated within plan: unique=%d logical=%d", firstPlan.UniqueSize, firstPlan.LogicalSize)
+	}
+
+	modified := make([]byte, 0, len(original)+4096)
+	modified = append(modified, original[:2<<20]...)
+	modified = append(modified, bytes.Repeat([]byte("changed!"), 512)...)
+	modified = append(modified, original[2<<20:]...)
+	if err := os.WriteFile(primaryPath, modified, 0o640); err != nil {
+		t.Fatalf("modify primary: %v", err)
+	}
+	task.StartedAt = task.StartedAt.Add(time.Hour)
+	secondPlan, err := store.BuildPlan(ctx, task, NopLogWriter{})
+	if err != nil {
+		t.Fatalf("build second plan: %v", err)
+	}
+	secondKey := store.SnapshotKey(task.ID, 2, task.StartedAt)
+	secondResult, err := store.Upload(ctx, provider, secondPlan, secondKey)
+	if closeErr := secondPlan.Close(); closeErr != nil {
+		t.Fatalf("close second plan: %v", closeErr)
+	}
+	if err != nil {
+		t.Fatalf("upload second snapshot: %v", err)
+	}
+	if secondResult.ReusedBytes <= secondResult.LogicalSize/3 {
+		t.Fatalf("second snapshot reused too little data: %+v", secondResult)
+	}
+	if secondResult.UploadedBytes >= secondResult.LogicalSize {
+		t.Fatalf("incremental upload was not smaller than logical data: %+v", secondResult)
+	}
+
+	verify, err := store.Verify(ctx, provider, secondKey, secondResult.Checksum)
+	if err != nil {
+		t.Fatalf("verify repository: %v", err)
+	}
+	if verify.Chunks == 0 || verify.Bytes == 0 {
+		t.Fatalf("empty verification result: %+v", verify)
+	}
+
+	restoreRoot := filepath.Join(tempDir, "restore")
+	restoreTask := task
+	restoreTask.RestoreTargetPath = restoreRoot
+	if err := store.Restore(ctx, provider, secondKey, strings.Repeat("0", sha256.Size*2), restoreTask, NopLogWriter{}); err == nil {
+		t.Fatal("restore accepted a mismatched snapshot checksum")
+	}
+	if err := store.Restore(ctx, provider, secondKey, "", restoreTask, NopLogWriter{}); err == nil {
+		t.Fatal("restore accepted a missing snapshot checksum")
+	}
+	if err := store.Restore(ctx, provider, secondKey, secondResult.Checksum, restoreTask, NopLogWriter{}); err != nil {
+		t.Fatalf("restore snapshot: %v", err)
+	}
+	restored, err := os.ReadFile(filepath.Join(restoreRoot, filepath.Base(sourceDir), "primary.bin"))
+	if err != nil {
+		t.Fatalf("read restored primary: %v", err)
+	}
+	if !bytes.Equal(restored, modified) {
+		t.Fatalf("restored primary differs from source")
+	}
+	if info, err := os.Stat(filepath.Join(restoreRoot, filepath.Base(sourceDir), "empty")); err != nil || !info.IsDir() {
+		t.Fatalf("empty directory was not restored: info=%v err=%v", info, err)
+	}
+
+	if err := provider.Delete(ctx, firstKey); err != nil {
+		t.Fatalf("delete first snapshot: %v", err)
+	}
+	if _, err := store.Prune(ctx, provider); err != nil {
+		t.Fatalf("prune with live snapshot: %v", err)
+	}
+	if err := provider.Delete(ctx, secondKey); err != nil {
+		t.Fatalf("delete second snapshot: %v", err)
+	}
+	pruned, err := store.Prune(ctx, provider)
+	if err != nil {
+		t.Fatalf("prune empty repository: %v", err)
+	}
+	if pruned.DeletedPacks == 0 || pruned.DeletedIndexes == 0 {
+		t.Fatalf("prune did not reclaim repository data: %+v", pruned)
+	}
+	if objects, err := provider.List(ctx, repositoryPackPrefix); err != nil || len(objects) != 0 {
+		t.Fatalf("packs remain after prune: objects=%v err=%v", objects, err)
+	}
+}
+
+func TestRepositoryRestoreRejectsUnsafeSnapshotMetadata(t *testing.T) {
+	cases := []struct {
+		name    string
+		entries []repositoryEntry
+	}{
+		{
+			name:    "path traversal",
+			entries: []repositoryEntry{{Path: "../escape", Kind: "directory", Mode: 0o755}},
+		},
+		{
+			name: "entry below symlink",
+			entries: []repositoryEntry{
+				{Path: "link", Kind: "symlink", Mode: 0o777, LinkTarget: "inside"},
+				{Path: "link/payload", Kind: "file", Mode: 0o600, Size: 1, Chunks: []string{"p-" + strings.Repeat("0", sha256.Size*2)}},
+			},
+		},
+		{
+			name:    "escaping symlink target",
+			entries: []repositoryEntry{{Path: "escape", Kind: "symlink", Mode: 0o777, LinkTarget: "../outside"}},
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx := context.Background()
+			store := NewRepositoryStore(nil)
+			provider := newMemoryRepositoryProvider()
+			snapshot := repositorySnapshot{
+				Version:     repositoryFormatVersion,
+				TaskID:      1,
+				CreatedAt:   time.Now().UTC(),
+				Compression: "none",
+				Entries:     tc.entries,
+			}
+			data, err := store.encodeSnapshot(snapshot)
+			if err != nil {
+				t.Fatalf("encodeSnapshot returned error: %v", err)
+			}
+			key := store.SnapshotKey(1, 1, snapshot.CreatedAt)
+			if err := provider.Upload(ctx, key, bytes.NewReader(data), int64(len(data)), nil); err != nil {
+				t.Fatalf("Upload snapshot returned error: %v", err)
+			}
+			digest := sha256.Sum256(data)
+			task := TaskSpec{SourcePath: filepath.Join(t.TempDir(), "source"), RestoreTargetPath: filepath.Join(t.TempDir(), "restore")}
+			if err := store.Restore(ctx, provider, key, fmt.Sprintf("%x", digest[:]), task, NopLogWriter{}); err == nil {
+				t.Fatal("restore accepted unsafe snapshot metadata")
+			}
+		})
+	}
+}
+
+func TestRepositoryRestorePreservesDirectoryWhenSnapshotContainsSymlink(t *testing.T) {
+	ctx := context.Background()
+	store := NewRepositoryStore(nil)
+	provider := newMemoryRepositoryProvider()
+	snapshot := repositorySnapshot{
+		Version:     repositoryFormatVersion,
+		TaskID:      1,
+		CreatedAt:   time.Now().UTC(),
+		Compression: "none",
+		Entries:     []repositoryEntry{{Path: "link", Kind: "symlink", Mode: 0o777, LinkTarget: "inside"}},
+	}
+	data, err := store.encodeSnapshot(snapshot)
+	if err != nil {
+		t.Fatalf("encodeSnapshot returned error: %v", err)
+	}
+	key := store.SnapshotKey(1, 1, snapshot.CreatedAt)
+	if err := provider.Upload(ctx, key, bytes.NewReader(data), int64(len(data)), nil); err != nil {
+		t.Fatalf("Upload snapshot returned error: %v", err)
+	}
+	digest := sha256.Sum256(data)
+	restoreRoot := filepath.Join(t.TempDir(), "restore")
+	markerPath := filepath.Join(restoreRoot, "link", "keep.txt")
+	if err := os.MkdirAll(filepath.Dir(markerPath), 0o755); err != nil {
+		t.Fatalf("MkdirAll marker parent: %v", err)
+	}
+	if err := os.WriteFile(markerPath, []byte("keep"), 0o600); err != nil {
+		t.Fatalf("WriteFile marker: %v", err)
+	}
+	task := TaskSpec{SourcePath: filepath.Join(t.TempDir(), "source"), RestoreTargetPath: restoreRoot}
+	if err := store.Restore(ctx, provider, key, fmt.Sprintf("%x", digest[:]), task, NopLogWriter{}); err == nil {
+		t.Fatal("restore replaced an existing directory with a symlink")
+	}
+	if data, err := os.ReadFile(markerPath); err != nil || string(data) != "keep" {
+		t.Fatalf("existing directory content changed: data=%q err=%v", data, err)
+	}
+}
+
+func TestRepositoryRejectsOversizedChunkLocation(t *testing.T) {
+	ctx := context.Background()
+	store := NewRepositoryStore(nil)
+	provider := newMemoryRepositoryProvider()
+	chunkID := "p-" + strings.Repeat("0", sha256.Size*2)
+	packID := strings.Repeat("a", sha256.Size*2)
+	segment := repositoryIndexSegment{
+		Version: repositoryFormatVersion,
+		Pack:    fmt.Sprintf("%s/%s/%s.pack", repositoryPackPrefix, packID[:2], packID),
+		Chunks: map[string]repositoryChunkLocation{
+			chunkID: {Pack: fmt.Sprintf("%s/%s/%s.pack", repositoryPackPrefix, packID[:2], packID), Offset: 0, Length: repositoryMaxEncoded + 1, PlainSize: 1, Compression: "none"},
+		},
+	}
+	data, err := json.Marshal(segment)
+	if err != nil {
+		t.Fatalf("Marshal index returned error: %v", err)
+	}
+	indexKey := fmt.Sprintf("%s/%s.json", repositoryIndexPrefix, packID)
+	if err := provider.Upload(ctx, indexKey, bytes.NewReader(data), int64(len(data)), nil); err != nil {
+		t.Fatalf("Upload index returned error: %v", err)
+	}
+	if _, err := store.loadIndex(ctx, provider); err == nil {
+		t.Fatal("loadIndex accepted an oversized encoded chunk")
+	}
+}
+
+func TestRepositoryRejectsIndexPackMismatch(t *testing.T) {
+	ctx := context.Background()
+	store := NewRepositoryStore(nil)
+	provider := newMemoryRepositoryProvider()
+	chunkID := "p-" + strings.Repeat("0", sha256.Size*2)
+	indexID := strings.Repeat("a", sha256.Size*2)
+	otherPackID := strings.Repeat("b", sha256.Size*2)
+	expectedPack := fmt.Sprintf("%s/%s/%s.pack", repositoryPackPrefix, indexID[:2], indexID)
+	segment := repositoryIndexSegment{
+		Version: repositoryFormatVersion,
+		Pack:    expectedPack,
+		Chunks: map[string]repositoryChunkLocation{
+			chunkID: {
+				Pack:        fmt.Sprintf("%s/%s/%s.pack", repositoryPackPrefix, otherPackID[:2], otherPackID),
+				Offset:      0,
+				Length:      1,
+				PlainSize:   1,
+				Compression: "none",
+			},
+		},
+	}
+	data, err := json.Marshal(segment)
+	if err != nil {
+		t.Fatalf("Marshal index returned error: %v", err)
+	}
+	indexKey := fmt.Sprintf("%s/%s.json", repositoryIndexPrefix, indexID)
+	if err := provider.Upload(ctx, indexKey, bytes.NewReader(data), int64(len(data)), nil); err != nil {
+		t.Fatalf("Upload index returned error: %v", err)
+	}
+	if _, err := store.loadIndex(ctx, provider); err == nil {
+		t.Fatal("loadIndex accepted a chunk location pointing to a different pack")
+	}
+}
+
+type memoryRepositoryProvider struct {
+	mu      sync.RWMutex
+	objects map[string][]byte
+	times   map[string]time.Time
+}
+
+func newMemoryRepositoryProvider() *memoryRepositoryProvider {
+	return &memoryRepositoryProvider{objects: make(map[string][]byte), times: make(map[string]time.Time)}
+}
+
+func (p *memoryRepositoryProvider) Type() storage.ProviderType           { return "memory" }
+func (p *memoryRepositoryProvider) TestConnection(context.Context) error { return nil }
+
+func (p *memoryRepositoryProvider) Upload(_ context.Context, key string, reader io.Reader, size int64, _ map[string]string) error {
+	data, err := io.ReadAll(reader)
+	if err != nil {
+		return err
+	}
+	if int64(len(data)) != size {
+		return fmt.Errorf("size mismatch for %s: %d != %d", key, len(data), size)
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.objects[key] = append([]byte(nil), data...)
+	p.times[key] = time.Now().UTC()
+	return nil
+}
+
+func (p *memoryRepositoryProvider) Download(_ context.Context, key string) (io.ReadCloser, error) {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	data, ok := p.objects[key]
+	if !ok {
+		return nil, fmt.Errorf("object %s not found", key)
+	}
+	return io.NopCloser(bytes.NewReader(append([]byte(nil), data...))), nil
+}
+
+func (p *memoryRepositoryProvider) DownloadRange(_ context.Context, key string, offset, length int64) (io.ReadCloser, error) {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	data, ok := p.objects[key]
+	if !ok {
+		return nil, fmt.Errorf("object %s not found", key)
+	}
+	if offset < 0 || length <= 0 || offset+length > int64(len(data)) {
+		return nil, fmt.Errorf("invalid range %d:%d for %s", offset, length, key)
+	}
+	return io.NopCloser(bytes.NewReader(append([]byte(nil), data[offset:offset+length]...))), nil
+}
+
+func (p *memoryRepositoryProvider) Delete(_ context.Context, key string) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if _, ok := p.objects[key]; !ok {
+		return fmt.Errorf("object %s not found", key)
+	}
+	delete(p.objects, key)
+	delete(p.times, key)
+	return nil
+}
+
+func (p *memoryRepositoryProvider) List(_ context.Context, prefix string) ([]storage.ObjectInfo, error) {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	result := make([]storage.ObjectInfo, 0)
+	for key, data := range p.objects {
+		if strings.HasPrefix(key, prefix) {
+			result = append(result, storage.ObjectInfo{Key: key, Size: int64(len(data)), UpdatedAt: p.times[key]})
+		}
+	}
+	sort.Slice(result, func(i, j int) bool { return result[i].Key < result[j].Key })
+	return result, nil
+}
--- a/server/internal/backup/retention/service.go
+++ b/server/internal/backup/retention/service.go
@@ -2,11 +2,13 @@ package retention

 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"sort"
 	"strings"
 	"time"

+	"backupx/server/internal/backup"
 	"backupx/server/internal/model"
 	"backupx/server/internal/repository"
 	"backupx/server/internal/storage"
@@ -40,16 +42,48 @@ type CleanupResult struct {
 	Warnings       []string
 }

-type Service struct {
-	records repository.BackupRecordRepository
-	now     func() time.Time
+type cleanupObject struct {
+	targetID uint
+	path     string
 }

-func NewService(records repository.BackupRecordRepository) *Service {
-	return &Service{records: records, now: func() time.Time { return time.Now().UTC() }}
+type storedUploadResult struct {
+	StorageTargetID uint   `json:"storageTargetId"`
+	Status          string `json:"status"`
+	StoragePath     string `json:"storagePath"`
+}
+
+type Service struct {
+	records       repository.BackupRecordRepository
+	repositoryKey []byte
+	now           func() time.Time
+}
+
+func NewService(records repository.BackupRecordRepository, repositoryKey ...[]byte) *Service {
+	var key []byte
+	if len(repositoryKey) > 0 {
+		key = append([]byte(nil), repositoryKey[0]...)
+	}
+	return &Service{records: records, repositoryKey: key, now: func() time.Time { return time.Now().UTC() }}
 }

 func (s *Service) Cleanup(ctx context.Context, task *model.BackupTask, provider storage.StorageProvider) (*CleanupResult, error) {
+	return s.cleanup(ctx, task, func(uint) (storage.StorageProvider, bool) {
+		return provider, provider != nil
+	})
+}
+
+// CleanupProviders applies one retention decision to every successful copy of
+// a record before deleting its database row. This prevents multi-target tasks
+// from leaving stale objects after the first target removes the shared record.
+func (s *Service) CleanupProviders(ctx context.Context, task *model.BackupTask, providers map[uint]storage.StorageProvider) (*CleanupResult, error) {
+	return s.cleanup(ctx, task, func(targetID uint) (storage.StorageProvider, bool) {
+		provider, ok := providers[targetID]
+		return provider, ok && provider != nil
+	})
+}
+
+func (s *Service) cleanup(ctx context.Context, task *model.BackupTask, resolveProvider func(uint) (storage.StorageProvider, bool)) (*CleanupResult, error) {
 	if task == nil {
 		return nil, fmt.Errorf("backup task is required")
 	}
@@ -67,17 +101,35 @@ func (s *Service) Cleanup(ctx context.Context, task *model.BackupTask, provider
 	// 差异链保护：保留仍被存活差异依赖的全量，避免删除基线后差异无法恢复。
 	candidates = protectDifferentialBases(records, candidates)
 	result := &CleanupResult{}
+	repositoryProviders := make(map[uint]storage.StorageProvider)
+	touchedProviders := make(map[uint]storage.StorageProvider)
 	for _, record := range candidates {
-		if strings.TrimSpace(record.StoragePath) != "" {
-			if provider == nil {
-				result.Warnings = append(result.Warnings, fmt.Sprintf("record %d missing storage provider for cleanup", record.ID))
+		objects, objectErr := cleanupObjectsForRecord(record)
+		if objectErr != nil {
+			result.Warnings = append(result.Warnings, fmt.Sprintf("decode storage copies for record %d failed: %v", record.ID, objectErr))
+			continue
+		}
+		allObjectsDeleted := true
+		for _, object := range objects {
+			provider, ok := resolveProvider(object.targetID)
+			if !ok {
+				result.Warnings = append(result.Warnings, fmt.Sprintf("record %d missing storage provider %d for cleanup", record.ID, object.targetID))
+				allObjectsDeleted = false
 				continue
 			}
-			if err := provider.Delete(ctx, record.StoragePath); err != nil {
-				result.Warnings = append(result.Warnings, fmt.Sprintf("delete storage object %s failed: %v", record.StoragePath, err))
+			if err := provider.Delete(ctx, object.path); err != nil {
+				result.Warnings = append(result.Warnings, fmt.Sprintf("delete storage object %s from target %d failed: %v", object.path, object.targetID, err))
+				allObjectsDeleted = false
 				continue
 			}
 			result.DeletedObjects++
+			touchedProviders[object.targetID] = provider
+			if record.BackupKind == model.BackupKindRepository {
+				repositoryProviders[object.targetID] = provider
+			}
+		}
+		if !allObjectsDeleted {
+			continue
 		}
 		if err := s.records.Delete(ctx, record.ID); err != nil {
 			result.Warnings = append(result.Warnings, fmt.Sprintf("delete backup record %d failed: %v", record.ID, err))
@@ -85,13 +137,25 @@ func (s *Service) Cleanup(ctx context.Context, task *model.BackupTask, provider
 		}
 		result.DeletedRecords++
 	}
+	for targetID, provider := range repositoryProviders {
+		pruned, pruneErr := backup.NewRepositoryStore(s.repositoryKey).Prune(ctx, provider)
+		if pruneErr != nil {
+			result.Warnings = append(result.Warnings, fmt.Sprintf("prune CDC repository on target %d failed: %v", targetID, pruneErr))
+		} else {
+			result.DeletedObjects += pruned.DeletedPacks + pruned.DeletedIndexes
+		}
+	}

 	// 清理空目录：收集被删除文件的父目录，尝试移除空目录
-	if dirCleaner, ok := provider.(storage.StorageDirCleaner); ok && result.DeletedObjects > 0 {
+	for targetID, provider := range touchedProviders {
+		dirCleaner, ok := provider.(storage.StorageDirCleaner)
+		if !ok {
+			continue
+		}
 		prefixes := collectDirPrefixes(candidates)
 		for _, prefix := range prefixes {
 			if err := dirCleaner.RemoveEmptyDirs(ctx, prefix); err != nil {
-				result.Warnings = append(result.Warnings, fmt.Sprintf("cleanup empty dirs for %s: %v", prefix, err))
+				result.Warnings = append(result.Warnings, fmt.Sprintf("cleanup empty dirs for %s on target %d: %v", prefix, targetID, err))
 			}
 		}
 	}
@@ -99,6 +163,43 @@ func (s *Service) Cleanup(ctx context.Context, task *model.BackupTask, provider
 	return result, nil
 }

+func cleanupObjectsForRecord(record model.BackupRecord) ([]cleanupObject, error) {
+	defaultPath := strings.TrimSpace(record.StoragePath)
+	if strings.TrimSpace(record.StorageUploadResults) == "" {
+		if defaultPath == "" {
+			return nil, nil
+		}
+		return []cleanupObject{{targetID: record.StorageTargetID, path: defaultPath}}, nil
+	}
+	var results []storedUploadResult
+	if err := json.Unmarshal([]byte(record.StorageUploadResults), &results); err != nil {
+		return nil, err
+	}
+	objects := make([]cleanupObject, 0, len(results))
+	seen := make(map[uint]struct{}, len(results))
+	for _, result := range results {
+		if !strings.EqualFold(strings.TrimSpace(result.Status), model.BackupRecordStatusSuccess) {
+			continue
+		}
+		objectPath := strings.TrimSpace(result.StoragePath)
+		if objectPath == "" {
+			objectPath = defaultPath
+		}
+		if objectPath == "" {
+			continue
+		}
+		if _, exists := seen[result.StorageTargetID]; exists {
+			continue
+		}
+		seen[result.StorageTargetID] = struct{}{}
+		objects = append(objects, cleanupObject{targetID: result.StorageTargetID, path: objectPath})
+	}
+	if len(objects) == 0 && defaultPath != "" {
+		return nil, fmt.Errorf("successful record has no successful storage copy")
+	}
+	return objects, nil
+}
+
 // protectDifferentialBases 从删除候选中剔除「仍被存活差异依赖的全量」，
 // 避免删除基线后其差异备份失去依据、无法恢复。全量仅当其全部差异都已过期/删除时才会被清理。
 func protectDifferentialBases(all []model.BackupRecord, candidates []model.BackupRecord) []model.BackupRecord {
--- a/server/internal/backup/retention/service_test.go
+++ b/server/internal/backup/retention/service_test.go
@@ -221,3 +221,66 @@ func TestCleanupDeletesExpiredRecords(t *testing.T) {
 		t.Fatalf("unexpected deleted objects: %#v", provider.deleted)
 	}
 }
+
+func TestCleanupProvidersDeletesEverySuccessfulCopyBeforeRecord(t *testing.T) {
+	now := time.Date(2026, 3, 7, 16, 0, 0, 0, time.UTC)
+	completedNew := now.Add(-time.Hour)
+	completedOld := now.Add(-24 * time.Hour)
+	repo := &fakeRecordRepository{records: []model.BackupRecord{
+		{ID: 2, TaskID: 1, StoragePath: "records/2", Status: model.BackupRecordStatusSuccess, CompletedAt: &completedNew},
+		{
+			ID: 1, TaskID: 1, StoragePath: "records/1", Status: model.BackupRecordStatusSuccess, CompletedAt: &completedOld,
+			StorageUploadResults: `[{"storageTargetId":11,"status":"success","storagePath":"first/1"},{"storageTargetId":12,"status":"success","storagePath":"second/1"},{"storageTargetId":13,"status":"failed"}]`,
+		},
+	}}
+	first := &fakeProvider{}
+	second := &fakeProvider{}
+	service := NewService(repo)
+	service.now = func() time.Time { return now }
+
+	result, err := service.CleanupProviders(context.Background(), &model.BackupTask{ID: 1, MaxBackups: 1}, map[uint]storage.StorageProvider{
+		11: first,
+		12: second,
+	})
+	if err != nil {
+		t.Fatalf("CleanupProviders returned error: %v", err)
+	}
+	if result.DeletedRecords != 1 || result.DeletedObjects != 2 || len(result.Warnings) != 0 {
+		t.Fatalf("unexpected cleanup result: %#v", result)
+	}
+	if len(repo.deleted) != 1 || repo.deleted[0] != 1 {
+		t.Fatalf("unexpected deleted records: %#v", repo.deleted)
+	}
+	if len(first.deleted) != 1 || first.deleted[0] != "first/1" {
+		t.Fatalf("unexpected first-target deletes: %#v", first.deleted)
+	}
+	if len(second.deleted) != 1 || second.deleted[0] != "second/1" {
+		t.Fatalf("unexpected second-target deletes: %#v", second.deleted)
+	}
+}
+
+func TestCleanupProvidersKeepsRecordWhenCopyProviderIsUnavailable(t *testing.T) {
+	now := time.Date(2026, 3, 7, 16, 0, 0, 0, time.UTC)
+	completedNew := now.Add(-time.Hour)
+	completedOld := now.Add(-24 * time.Hour)
+	repo := &fakeRecordRepository{records: []model.BackupRecord{
+		{ID: 2, TaskID: 1, StoragePath: "records/2", Status: model.BackupRecordStatusSuccess, CompletedAt: &completedNew},
+		{
+			ID: 1, TaskID: 1, StoragePath: "records/1", Status: model.BackupRecordStatusSuccess, CompletedAt: &completedOld,
+			StorageUploadResults: `[{"storageTargetId":11,"status":"success","storagePath":"first/1"},{"storageTargetId":12,"status":"success","storagePath":"second/1"}]`,
+		},
+	}}
+	first := &fakeProvider{}
+	service := NewService(repo)
+
+	result, err := service.CleanupProviders(context.Background(), &model.BackupTask{ID: 1, MaxBackups: 1}, map[uint]storage.StorageProvider{11: first})
+	if err != nil {
+		t.Fatalf("CleanupProviders returned error: %v", err)
+	}
+	if result.DeletedRecords != 0 || result.DeletedObjects != 1 || len(result.Warnings) != 1 {
+		t.Fatalf("unexpected safe partial-cleanup result: %#v", result)
+	}
+	if len(repo.deleted) != 0 {
+		t.Fatalf("record must remain until all copies are deleted: %#v", repo.deleted)
+	}
+}
--- a/server/internal/backup/temp_files.go
+++ b/server/internal/backup/temp_files.go
@@ -55,6 +55,17 @@ func BuildStorageKey(backupType string, startedAt time.Time, fileName string) st
 	return filepath.ToSlash(filepath.Join("BackupX", typeName, startedAt.UTC().Format("060102"), fileName))
 }

+// BuildRecordStorageKey gives remote-Agent artifacts a record-owned namespace.
+// The Master validates this namespace before accepting a relayed upload, so one
+// Agent cannot overwrite another record's object on centrally mounted storage.
+func BuildRecordStorageKey(backupType string, startedAt time.Time, recordID uint, fileName string) string {
+	typeName := strings.TrimSpace(strings.ToLower(backupType))
+	if typeName == "" {
+		typeName = "file"
+	}
+	return filepath.ToSlash(filepath.Join("BackupX", typeName, startedAt.UTC().Format("060102"), "records", fmt.Sprintf("%d", recordID), fileName))
+}
+
 func sanitizeTaskName(value string) string {
 	trimmed := strings.TrimSpace(strings.ToLower(value))
 	trimmed = strings.ReplaceAll(trimmed, " ", "-")
--- a/server/internal/http/agent_handler.go
+++ b/server/internal/http/agent_handler.go
@@ -156,6 +156,44 @@ func (h *AgentHandler) UpdateRecord(c *gin.Context) {
 	response.Success(c, gin.H{"status": "ok"})
 }

+// UploadArtifact streams a remote source artifact into storage mounted only on
+// the Master. The request body is never buffered as a whole in memory or disk.
+func (h *AgentHandler) UploadArtifact(c *gin.Context) {
+	node, err := h.agentService.AuthenticatedNode(c.Request.Context(), extractToken(c))
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	recordID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	targetID, err := strconv.ParseUint(c.Param("targetId"), 10, 32)
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	if c.Request.ContentLength < 0 {
+		c.JSON(stdhttp.StatusLengthRequired, gin.H{"code": "CONTENT_LENGTH_REQUIRED", "message": "artifact content length is required"})
+		return
+	}
+	if err := h.agentService.UploadArtifact(
+		c.Request.Context(),
+		node,
+		uint(recordID),
+		uint(targetID),
+		c.GetHeader("X-BackupX-Object-Key"),
+		c.Request.ContentLength,
+		c.GetHeader("X-BackupX-SHA256"),
+		c.Request.Body,
+	); err != nil {
+		response.Error(c, err)
+		return
+	}
+	response.Success(c, gin.H{"status": "ok"})
+}
+
 // GetRestoreSpec Agent 拉取恢复规格。
 func (h *AgentHandler) GetRestoreSpec(c *gin.Context) {
 	if h.restoreService == nil {
@@ -208,6 +246,34 @@ func (h *AgentHandler) UpdateRestore(c *gin.Context) {
 	response.Success(c, gin.H{"status": "ok"})
 }

+// DownloadRestoreArtifact streams a Master-local backup back to its source
+// Agent for restore without exposing the local storage configuration.
+func (h *AgentHandler) DownloadRestoreArtifact(c *gin.Context) {
+	if h.restoreService == nil {
+		c.JSON(stdhttp.StatusServiceUnavailable, gin.H{"code": "RESTORE_SERVICE_DISABLED", "message": "restore service is not enabled"})
+		return
+	}
+	node, err := h.agentService.AuthenticatedNode(c.Request.Context(), extractToken(c))
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	restoreID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	artifact, err := h.restoreService.DownloadAgentArtifact(c.Request.Context(), node, uint(restoreID))
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	c.DataFromReader(stdhttp.StatusOK, artifact.Size, "application/octet-stream", artifact.Reader, nil)
+	if err := artifact.Reader.Close(); err != nil {
+		_ = c.Error(err)
+	}
+}
+
 // Self 返回当前 Agent token 所属节点的状态，供安装脚本末尾探活。
 func (h *AgentHandler) Self(c *gin.Context) {
 	node, err := h.agentService.AuthenticatedNode(c.Request.Context(), extractToken(c))
--- a/server/internal/http/router.go
+++ b/server/internal/http/router.go
@@ -322,7 +322,9 @@ func NewRouter(deps RouterDependencies) *gin.Engine {
 			agent.POST("/commands/:id/result", agentHandler.SubmitCommandResult)
 			agent.GET("/tasks/:id", agentHandler.GetTaskSpec)
 			agent.POST("/records/:id", agentHandler.UpdateRecord)
+			agent.PUT("/records/:id/artifacts/:targetId", agentHandler.UploadArtifact)
 			agent.GET("/restores/:id/spec", agentHandler.GetRestoreSpec)
+			agent.GET("/restores/:id/artifact", agentHandler.DownloadRestoreArtifact)
 			agent.POST("/restores/:id", agentHandler.UpdateRestore)

 			// Agent v1（安装脚本探活用），仅 Self 端点
--- a/server/internal/installscript/deploy_install_test.go
+++ b/server/internal/installscript/deploy_install_test.go
@@ -39,3 +39,23 @@ func TestDeployInstallScriptSupportsReleasePackageLayout(t *testing.T) {
 		}
 	}
 }
+
+func TestDeployInstallScriptSupportsSourceBuildAndVerifiesFirstSetup(t *testing.T) {
+	scriptPath := filepath.Join("..", "..", "..", "deploy", "install.sh")
+	data, err := os.ReadFile(scriptPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	script := string(data)
+	for _, want := range []string{
+		`SOURCE_BIN_DEFAULT="$PROJECT_ROOT/server/bin/backupx"`,
+		`For a source install, run 'make build' in the repository root first.`,
+		`HEALTH_URL="${HEALTH_URL:-http://127.0.0.1:8340/api/auth/setup/status}"`,
+		`systemctl is-active --quiet "$SERVICE_NAME"`,
+		`System setup`,
+	} {
+		if !strings.Contains(script, want) {
+			t.Fatalf("install.sh missing %q", want)
+		}
+	}
+}
--- a/server/internal/model/backup_record.go
+++ b/server/internal/model/backup_record.go
@@ -9,9 +9,11 @@ const (
 )

 const (
-	// BackupKindFull 全量备份；BackupKindDifferential 差异备份（仅含自基线全量以来的变更）。
+	// BackupKindFull 全量归档；BackupKindDifferential 差异归档；
+	// BackupKindRepository 为可独立恢复的 CDC 内容寻址快照。
 	BackupKindFull         = "full"
 	BackupKindDifferential = "differential"
+	BackupKindRepository   = "repository"
 )

 type BackupRecord struct {
@@ -20,20 +22,22 @@ type BackupRecord struct {
 	Task            BackupTask    `json:"task,omitempty"`
 	StorageTargetID uint          `gorm:"column:storage_target_id;index;not null" json:"storageTargetId"`
 	StorageTarget   StorageTarget `json:"storageTarget,omitempty"`
-	// NodeID 执行该次备份的节点（0 = 本机 Master）。用于集群中识别 local_disk 类型
-	// 存储的归属节点，避免 Master 端试图跨节点访问远程 Agent 的本地存储。
-	NodeID               uint   `gorm:"column:node_id;index;default:0" json:"nodeId"`
-	Status               string `gorm:"size:20;index;not null" json:"status"`
-	FileName             string `gorm:"column:file_name;size:255" json:"fileName"`
-	FileSize             int64  `gorm:"column:file_size;not null;default:0" json:"fileSize"`
-	Checksum             string `gorm:"column:checksum;size:64" json:"checksum"`
-	StoragePath          string `gorm:"column:storage_path;size:500" json:"storagePath"`
+	// NodeID 执行该次备份的节点（0 = 本机 Master）。StorageTransferMode 进一步
+	// 区分远程 Agent 直写与 Master 中转，避免在错误节点访问 local_disk。
+	NodeID      uint   `gorm:"column:node_id;index;default:0" json:"nodeId"`
+	Status      string `gorm:"size:20;index;not null" json:"status"`
+	FileName    string `gorm:"column:file_name;size:255" json:"fileName"`
+	FileSize    int64  `gorm:"column:file_size;not null;default:0" json:"fileSize"`
+	Checksum    string `gorm:"column:checksum;size:64" json:"checksum"`
+	StoragePath string `gorm:"column:storage_path;size:500" json:"storagePath"`
+	// 空值表示旧版 Agent 直写；direct / master_relay 记录新协议的实际数据路径。
+	StorageTransferMode  string `gorm:"column:storage_transfer_mode;size:20" json:"storageTransferMode,omitempty"`
 	StorageUploadResults string `gorm:"column:storage_upload_results;type:text" json:"-"`
 	DurationSeconds      int    `gorm:"column:duration_seconds;not null;default:0" json:"durationSeconds"`
 	// Locked 保留锁定（法律保留）：为 true 时该备份不参与保留期/数量自动清理，
 	// 且禁止手动删除，直到显式解锁。用于保护合规快照、迁移前基线等关键备份。
 	Locked bool `gorm:"column:locked;not null;default:false;index" json:"locked"`
-	// BackupKind 备份类型：full（全量）/ differential（差异）。
+	// BackupKind 备份类型：full（全量）/ differential（差异）/ repository（CDC 快照）。
 	BackupKind string `gorm:"column:backup_kind;size:16;not null;default:'full';index" json:"backupKind"`
 	// BaseRecordID 差异备份所基于的全量备份记录 ID（全量记录为 0）。
 	BaseRecordID uint `gorm:"column:base_record_id;index;not null;default:0" json:"baseRecordId"`
--- a/server/internal/model/backup_task.go
+++ b/server/internal/model/backup_task.go
@@ -12,9 +12,11 @@ const (
 )

 const (
-	// BackupModeFull 全量模式（默认）；BackupModeDifferential 差异模式（仅文件类型本机任务）。
+	// BackupModeFull 全量模式（默认）；BackupModeDifferential 差异归档；
+	// BackupModeRepository 为 CDC 内容寻址仓库模式（仅文件类型本机任务）。
 	BackupModeFull         = "full"
 	BackupModeDifferential = "differential"
+	BackupModeRepository   = "repository"
 )

 const (
@@ -55,7 +57,8 @@ type BackupTask struct {
 	Compression   string `gorm:"size:10;not null;default:'gzip'" json:"compression"`
 	Encrypt       bool   `gorm:"not null;default:false" json:"encrypt"`
 	MaxBackups    int    `gorm:"column:max_backups;not null;default:10" json:"maxBackups"`
-	// BackupMode 备份模式：full（全量，默认）/ differential（差异）。差异仅支持本机文件任务。
+	// BackupMode 备份模式：full（全量，默认）/ differential（差异归档）/
+	// repository（FastCDC 分块、全局去重快照）。后两者仅支持本机文件任务。
 	BackupMode string `gorm:"column:backup_mode;size:16;not null;default:'full'" json:"backupMode"`
 	// DiffFullIntervalDays 差异模式下强制全量的间隔（天）：最近全量超过该天数则本次自动改为全量，
 	// 限制差异链跨度与单个差异体积。默认 7。
--- a/server/internal/service/agent_service.go
+++ b/server/internal/service/agent_service.go
@@ -2,15 +2,22 @@ package service

 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
+	"math"
+	"path"
 	"strings"
 	"time"

 	"backupx/server/internal/apperror"
+	"backupx/server/internal/backup"
 	"backupx/server/internal/model"
 	"backupx/server/internal/repository"
+	"backupx/server/internal/storage"
 	"backupx/server/internal/storage/codec"
 )

@@ -23,6 +30,7 @@ type AgentService struct {
 	storageRepo repository.StorageTargetRepository
 	cmdRepo     repository.AgentCommandRepository
 	restoreRepo repository.RestoreRecordRepository
+	registry    *storage.Registry
 	cipher      *codec.ConfigCipher
 }

@@ -33,6 +41,7 @@ func NewAgentService(
 	storageRepo repository.StorageTargetRepository,
 	cmdRepo repository.AgentCommandRepository,
 	cipher *codec.ConfigCipher,
+	registry *storage.Registry,
 ) *AgentService {
 	return &AgentService{
 		nodeRepo:    nodeRepo,
@@ -40,6 +49,7 @@ func NewAgentService(
 		recordRepo:  recordRepo,
 		storageRepo: storageRepo,
 		cmdRepo:     cmdRepo,
+		registry:    registry,
 		cipher:      cipher,
 	}
 }
@@ -145,10 +155,11 @@ type AgentTaskSpec struct {

 // AgentStorageTargetConfig 存储目标配置（已解密）
 type AgentStorageTargetConfig struct {
-	ID     uint            `json:"id"`
-	Type   string          `json:"type"`
-	Name   string          `json:"name"`
-	Config json.RawMessage `json:"config"`
+	ID           uint            `json:"id"`
+	Type         string          `json:"type"`
+	Name         string          `json:"name"`
+	Config       json.RawMessage `json:"config"`
+	TransferMode string          `json:"transferMode"`
 }

 // GetTaskSpec 返回 Agent 执行任务所需的完整规格。
@@ -187,11 +198,22 @@ func (s *AgentService) GetTaskSpec(ctx context.Context, node *model.Node, taskID
 		if err != nil {
 			return nil, fmt.Errorf("decrypt storage config: %w", err)
 		}
+		transferMode := storage.TransferModeDirect
+		if strings.EqualFold(target.Type, storage.TypeLocalDisk) {
+			var localConfig storage.LocalDiskConfig
+			if err := json.Unmarshal(configRaw, &localConfig); err != nil {
+				return nil, fmt.Errorf("decode local disk config: %w", err)
+			}
+			if localConfig.MasterRelay {
+				transferMode = storage.TransferModeMasterRelay
+			}
+		}
 		storageTargets = append(storageTargets, AgentStorageTargetConfig{
-			ID:     target.ID,
-			Type:   target.Type,
-			Name:   target.Name,
-			Config: json.RawMessage(configRaw),
+			ID:           target.ID,
+			Type:         target.Type,
+			Name:         target.Name,
+			Config:       json.RawMessage(configRaw),
+			TransferMode: transferMode,
 		})
 	}
 	return &AgentTaskSpec{
@@ -214,6 +236,102 @@ func (s *AgentService) GetTaskSpec(ctx context.Context, node *model.Node, taskID
 	}, nil
 }

+// UploadArtifact receives a remote Agent artifact as a stream and writes it
+// with a provider created on the Master. The first supported use is local_disk,
+// whose configured path belongs to the Master rather than the source Agent.
+func (s *AgentService) UploadArtifact(ctx context.Context, node *model.Node, recordID, targetID uint, objectKey string, size int64, checksum string, reader io.Reader) error {
+	if node == nil || reader == nil || s.registry == nil {
+		return apperror.BadRequest("AGENT_ARTIFACT_INVALID", "中转上传参数不完整", nil)
+	}
+	record, err := s.recordRepo.FindByID(ctx, recordID)
+	if err != nil {
+		return err
+	}
+	if record == nil {
+		return apperror.New(404, "BACKUP_RECORD_NOT_FOUND", "记录不存在", nil)
+	}
+	task, err := s.taskRepo.FindByID(ctx, record.TaskID)
+	if err != nil {
+		return err
+	}
+	if task == nil || !recordBelongsToNode(record, task, node.ID) {
+		return apperror.Unauthorized("BACKUP_RECORD_FORBIDDEN", "记录不属于当前节点", nil)
+	}
+	if isBackupRecordTerminal(record.Status) {
+		return apperror.BadRequest("BACKUP_RECORD_TERMINAL", "备份记录已结束，不能继续上传产物", nil)
+	}
+	allowedTarget := false
+	for _, configuredTargetID := range collectTargetIDs(task) {
+		if configuredTargetID == targetID {
+			allowedTarget = true
+			break
+		}
+	}
+	if !allowedTarget {
+		return apperror.Unauthorized("BACKUP_STORAGE_TARGET_FORBIDDEN", "存储目标不属于该任务", nil)
+	}
+	target, err := s.storageRepo.FindByID(ctx, targetID)
+	if err != nil {
+		return err
+	}
+	if target == nil || !strings.EqualFold(target.Type, storage.TypeLocalDisk) {
+		return apperror.BadRequest("AGENT_ARTIFACT_RELAY_UNSUPPORTED", "仅 Master 本地磁盘目标需要中转上传", nil)
+	}
+	configMap := map[string]any{}
+	if err := s.cipher.DecryptJSON(target.ConfigCiphertext, &configMap); err != nil {
+		return fmt.Errorf("decrypt storage config: %w", err)
+	}
+	masterRelay, _ := configMap["masterRelay"].(bool)
+	if !masterRelay {
+		return apperror.BadRequest("AGENT_ARTIFACT_RELAY_UNSUPPORTED", "该本地磁盘目标配置为 Agent 直接写入", nil)
+	}
+	cleanKey, keyErr := s.validateArtifactKey(record, task, objectKey, true)
+	if keyErr != nil {
+		return keyErr
+	}
+	checksum = strings.TrimSpace(checksum)
+	checksumBytes, checksumErr := hex.DecodeString(checksum)
+	if size < 0 || size == math.MaxInt64 || checksumErr != nil || len(checksumBytes) != sha256.Size {
+		return apperror.BadRequest("AGENT_ARTIFACT_INVALID", "中转上传需要有效的大小和 SHA-256", checksumErr)
+	}
+	if target.QuotaBytes > 0 {
+		usage, usageErr := s.recordRepo.StorageUsage(ctx)
+		if usageErr != nil {
+			return fmt.Errorf("read storage usage: %w", usageErr)
+		}
+		currentUsed := int64(0)
+		for _, item := range usage {
+			if item.StorageTargetID == targetID {
+				currentUsed = item.TotalSize
+				break
+			}
+		}
+		if currentUsed >= target.QuotaBytes || size > target.QuotaBytes-currentUsed {
+			return apperror.BadRequest("BACKUP_STORAGE_QUOTA_EXCEEDED", fmt.Sprintf("超出存储目标配额（当前 %d，新增 %d，配额 %d）", currentUsed, size, target.QuotaBytes), nil)
+		}
+	}
+	provider, err := s.registry.Create(ctx, target.Type, configMap)
+	if err != nil {
+		return fmt.Errorf("create master relay provider: %w", err)
+	}
+	limited := io.LimitReader(reader, size+1)
+	hashed := newHashingReader(limited)
+	metadata := map[string]string{
+		"taskId":       fmt.Sprintf("%d", task.ID),
+		"recordId":     fmt.Sprintf("%d", record.ID),
+		"sourceNodeId": fmt.Sprintf("%d", node.ID),
+		"transferMode": storage.TransferModeMasterRelay,
+	}
+	if err := provider.Upload(ctx, cleanKey, hashed, size, metadata); err != nil {
+		return errors.Join(fmt.Errorf("relay artifact to master storage: %w", err), provider.Delete(ctx, cleanKey))
+	}
+	if hashed.n != size || !strings.EqualFold(hashed.Sum(), checksum) {
+		deleteErr := provider.Delete(ctx, cleanKey)
+		return errors.Join(fmt.Errorf("relayed artifact integrity mismatch: received %d of %d bytes", hashed.n, size), deleteErr)
+	}
+	return nil
+}
+
 func (s *AgentService) ensureTaskSpecAccess(ctx context.Context, node *model.Node, task *model.BackupTask) error {
 	if task.NodeID == node.ID {
 		return nil
@@ -236,6 +354,7 @@ type AgentRecordUpdate struct {
 	Checksum             string                    `json:"checksum,omitempty"`
 	StoragePath          string                    `json:"storagePath,omitempty"`
 	StorageTargetID      uint                      `json:"storageTargetId,omitempty"`
+	StorageTransferMode  string                    `json:"storageTransferMode,omitempty"`
 	StorageUploadResults []StorageUploadResultItem `json:"storageUploadResults,omitempty"`
 	ErrorMessage         string                    `json:"errorMessage,omitempty"`
 	LogAppend            string                    `json:"logAppend,omitempty"` // 增量日志，追加到 record.log_content
@@ -260,6 +379,99 @@ func (s *AgentService) UpdateRecord(ctx context.Context, node *model.Node, recor
 	if isBackupRecordTerminal(record.Status) {
 		return nil
 	}
+	allowedTargets := make(map[uint]struct{})
+	for _, targetID := range collectTargetIDs(task) {
+		allowedTargets[targetID] = struct{}{}
+	}
+	targetCache := make(map[uint]*model.StorageTarget)
+	validateTransferMode := func(targetID uint, transferMode string) (string, error) {
+		if _, ok := allowedTargets[targetID]; !ok {
+			return "", apperror.Unauthorized("BACKUP_STORAGE_TARGET_FORBIDDEN", "存储目标不属于该任务", nil)
+		}
+		target := targetCache[targetID]
+		if target == nil {
+			var findErr error
+			target, findErr = s.storageRepo.FindByID(ctx, targetID)
+			if findErr != nil {
+				return "", findErr
+			}
+			if target == nil {
+				return "", apperror.BadRequest("BACKUP_STORAGE_TARGET_INVALID", "存储目标不存在", nil)
+			}
+			targetCache[targetID] = target
+		}
+		expectedMode := storage.TransferModeDirect
+		if strings.EqualFold(target.Type, storage.TypeLocalDisk) {
+			var localConfig storage.LocalDiskConfig
+			if err := s.cipher.DecryptJSON(target.ConfigCiphertext, &localConfig); err != nil {
+				return "", fmt.Errorf("decrypt storage config: %w", err)
+			}
+			if localConfig.MasterRelay {
+				expectedMode = storage.TransferModeMasterRelay
+			}
+		}
+		if transferMode != "" && transferMode != expectedMode {
+			return "", apperror.BadRequest("AGENT_STORAGE_TRANSFER_MODE_INVALID", "Agent 上报的存储传输模式与目标配置不一致", nil)
+		}
+		return expectedMode, nil
+	}
+	selectedTransferMode := ""
+	if update.StorageTargetID > 0 {
+		if _, ok := allowedTargets[update.StorageTargetID]; !ok {
+			return apperror.Unauthorized("BACKUP_STORAGE_TARGET_FORBIDDEN", "存储目标不属于该任务", nil)
+		}
+		var modeErr error
+		selectedTransferMode, modeErr = validateTransferMode(update.StorageTargetID, update.StorageTransferMode)
+		if modeErr != nil {
+			return modeErr
+		}
+	} else if update.StorageTransferMode != "" {
+		return apperror.BadRequest("AGENT_STORAGE_TRANSFER_MODE_INVALID", "传输模式缺少对应的存储目标", nil)
+	}
+	for index := range update.StorageUploadResults {
+		result := &update.StorageUploadResults[index]
+		expectedMode, err := validateTransferMode(result.StorageTargetID, result.TransferMode)
+		if err != nil {
+			return err
+		}
+		if result.FileSize < 0 || (result.Status != "" && result.Status != "success" && result.Status != "failed") {
+			return apperror.BadRequest("AGENT_ARTIFACT_INVALID", "Agent 上报的存储结果无效", nil)
+		}
+		if result.StoragePath != "" {
+			normalizedPath, err := s.validateArtifactKey(record, task, result.StoragePath, expectedMode == storage.TransferModeMasterRelay)
+			if err != nil {
+				return err
+			}
+			result.StoragePath = normalizedPath
+		}
+		result.TransferMode = expectedMode
+	}
+	if update.StoragePath != "" {
+		if update.StorageTargetID == 0 {
+			return apperror.BadRequest("AGENT_ARTIFACT_INVALID_PATH", "存储路径缺少对应的存储目标", nil)
+		}
+		cleanStoragePath, err := s.validateArtifactKey(record, task, update.StoragePath, selectedTransferMode == storage.TransferModeMasterRelay)
+		if err != nil {
+			return err
+		}
+		if update.FileName != "" && path.Base(cleanStoragePath) != update.FileName {
+			return apperror.BadRequest("AGENT_ARTIFACT_INVALID_PATH", "Agent 上报的文件名与存储路径不一致", nil)
+		}
+		update.StoragePath = cleanStoragePath
+	}
+	if update.Status != "" && update.Status != model.BackupRecordStatusRunning && update.Status != model.BackupRecordStatusSuccess && update.Status != model.BackupRecordStatusFailed {
+		return apperror.BadRequest("BACKUP_RECORD_STATUS_INVALID", "Agent 上报的备份状态无效", nil)
+	}
+	if update.FileSize < 0 || (update.FileName != "" && (path.Base(update.FileName) != update.FileName || strings.Contains(update.FileName, "\\"))) {
+		return apperror.BadRequest("AGENT_ARTIFACT_INVALID", "Agent 上报的备份文件信息无效", nil)
+	}
+	if update.Checksum != "" {
+		checksumBytes, checksumErr := hex.DecodeString(strings.TrimSpace(update.Checksum))
+		if checksumErr != nil || len(checksumBytes) != sha256.Size {
+			return apperror.BadRequest("AGENT_ARTIFACT_INVALID", "Agent 上报的 SHA-256 无效", checksumErr)
+		}
+		update.Checksum = strings.ToLower(strings.TrimSpace(update.Checksum))
+	}
 	if update.Status != "" {
 		record.Status = update.Status
 	}
@@ -277,6 +489,7 @@ func (s *AgentService) UpdateRecord(ctx context.Context, node *model.Node, recor
 	}
 	if update.StorageTargetID > 0 {
 		record.StorageTargetID = update.StorageTargetID
+		record.StorageTransferMode = selectedTransferMode
 	}
 	if len(update.StorageUploadResults) > 0 {
 		if resultsJSON, marshalErr := json.Marshal(update.StorageUploadResults); marshalErr == nil {
@@ -312,6 +525,27 @@ func (s *AgentService) UpdateRecord(ctx context.Context, node *model.Node, recor
 	return nil
 }

+func (s *AgentService) validateArtifactKey(record *model.BackupRecord, task *model.BackupTask, objectKey string, requireRecordNamespace bool) (string, error) {
+	if record == nil || task == nil {
+		return "", apperror.BadRequest("AGENT_ARTIFACT_INVALID_PATH", "无法确认中转对象归属", nil)
+	}
+	rawKey := objectKey
+	cleanKey := path.Clean(rawKey)
+	fileName := path.Base(cleanKey)
+	if rawKey == "" || strings.TrimSpace(rawKey) != rawKey || cleanKey == "." || path.IsAbs(cleanKey) || strings.HasPrefix(cleanKey, "../") || cleanKey != rawKey || strings.Contains(rawKey, "\\") || fileName == "." || fileName == "/" {
+		return "", apperror.BadRequest("AGENT_ARTIFACT_INVALID_PATH", "中转上传对象路径不安全", nil)
+	}
+	expectedKey := backup.BuildRecordStorageKey(task.Type, record.StartedAt, record.ID, fileName)
+	if requireRecordNamespace {
+		legacyKey := backup.BuildStorageKey(task.Type, record.StartedAt, fileName)
+		if cleanKey != expectedKey && cleanKey != legacyKey {
+			return "", apperror.BadRequest("AGENT_ARTIFACT_INVALID_PATH", "中转上传对象不属于当前备份记录", nil)
+		}
+		return expectedKey, nil
+	}
+	return cleanKey, nil
+}
+
 func recordBelongsToNode(record *model.BackupRecord, task *model.BackupTask, nodeID uint) bool {
 	if record.NodeID != 0 {
 		return record.NodeID == nodeID
--- a/server/internal/service/agent_service_test.go
+++ b/server/internal/service/agent_service_test.go
@@ -1,19 +1,26 @@
 package service

 import (
+	"bytes"
 	"context"
+	"crypto/sha256"
 	"errors"
+	"fmt"
+	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 	"time"

+	"backupx/server/internal/backup"
 	"backupx/server/internal/config"
 	"backupx/server/internal/database"
 	"backupx/server/internal/logger"
 	"backupx/server/internal/model"
 	"backupx/server/internal/repository"
+	"backupx/server/internal/storage"
 	"backupx/server/internal/storage/codec"
+	storageRclone "backupx/server/internal/storage/rclone"
 	"gorm.io/gorm"
 )

@@ -42,7 +49,7 @@ func newAgentServicePoolTestHarness(t *testing.T) (*AgentService, *gorm.DB, repo
 	if err := nodeRepo.Create(context.Background(), other); err != nil {
 		t.Fatalf("create other node: %v", err)
 	}
-	targetConfig, err := cipher.EncryptJSON(map[string]any{"basePath": t.TempDir()})
+	targetConfig, err := cipher.EncryptJSON(map[string]any{"basePath": t.TempDir(), "masterRelay": true})
 	if err != nil {
 		t.Fatalf("EncryptJSON returned error: %v", err)
 	}
@@ -76,7 +83,8 @@ func newAgentServicePoolTestHarness(t *testing.T) (*AgentService, *gorm.DB, repo
 	if err := recordRepo.Create(context.Background(), record); err != nil {
 		t.Fatalf("create record: %v", err)
 	}
-	return NewAgentService(nodeRepo, taskRepo, recordRepo, storageRepo, cmdRepo, cipher), db, recordRepo, cmdRepo, owner, other
+	storageRegistry := storage.NewRegistry(storageRclone.NewLocalDiskFactory())
+	return NewAgentService(nodeRepo, taskRepo, recordRepo, storageRepo, cmdRepo, cipher, storageRegistry), db, recordRepo, cmdRepo, owner, other
 }

 func TestAgentServicePooledTaskUsesRecordNodeForSpecAndRecordUpdates(t *testing.T) {
@@ -90,19 +98,27 @@ func TestAgentServicePooledTaskUsesRecordNodeForSpecAndRecordUpdates(t *testing.
 	if spec.TaskID != 1 || len(spec.StorageTargets) != 1 {
 		t.Fatalf("unexpected spec: %#v", spec)
 	}
+	if spec.StorageTargets[0].TransferMode != storage.TransferModeMasterRelay {
+		t.Fatalf("expected local disk to use Master relay, got %#v", spec.StorageTargets[0])
+	}
 	if _, err := svc.GetTaskSpec(ctx, other, 1); err == nil {
 		t.Fatal("expected non-owner node to be forbidden from pooled task spec")
 	}
+	record, err := records.FindByID(ctx, 1)
+	if err != nil {
+		t.Fatalf("FindByID record returned error: %v", err)
+	}
+	storagePath := backup.BuildRecordStorageKey("file", record.StartedAt, record.ID, "backup.tar.gz")

 	if err := svc.UpdateRecord(ctx, owner, 1, AgentRecordUpdate{
-		Status:          model.BackupRecordStatusSuccess,
-		FileName:        "backup.tar.gz",
-		FileSize:        123,
-		StoragePath:     "tasks/1/backup.tar.gz",
-		StorageTargetID: 2,
+		Status:              model.BackupRecordStatusSuccess,
+		FileName:            "backup.tar.gz",
+		FileSize:            123,
+		StoragePath:         storagePath,
+		StorageTargetID:     1,
+		StorageTransferMode: storage.TransferModeMasterRelay,
 		StorageUploadResults: []StorageUploadResultItem{
-			{StorageTargetID: 1, StorageTargetName: "first", Status: "failed", Error: "boom"},
-			{StorageTargetID: 2, StorageTargetName: "second", Status: "success", StoragePath: "tasks/1/backup.tar.gz", FileSize: 123},
+			{StorageTargetID: 1, StorageTargetName: "local", Status: "success", StoragePath: storagePath, FileSize: 123, TransferMode: storage.TransferModeMasterRelay},
 		},
 	}); err != nil {
 		t.Fatalf("owner UpdateRecord returned error: %v", err)
@@ -114,10 +130,13 @@ func TestAgentServicePooledTaskUsesRecordNodeForSpecAndRecordUpdates(t *testing.
 	if updated.Status != model.BackupRecordStatusSuccess || updated.NodeID != owner.ID {
 		t.Fatalf("unexpected updated record: %#v", updated)
 	}
-	if updated.StorageTargetID != 2 {
-		t.Fatalf("expected successful storage target id 2, got %d", updated.StorageTargetID)
+	if updated.StorageTargetID != 1 {
+		t.Fatalf("expected successful storage target id 1, got %d", updated.StorageTargetID)
 	}
-	if !strings.Contains(updated.StorageUploadResults, `"storageTargetName":"second"`) {
+	if updated.StorageTransferMode != storage.TransferModeMasterRelay {
+		t.Fatalf("expected Master relay transfer mode, got %q", updated.StorageTransferMode)
+	}
+	if !strings.Contains(updated.StorageUploadResults, `"storageTargetName":"local"`) {
 		t.Fatalf("expected upload results to be persisted, got %q", updated.StorageUploadResults)
 	}
 	if err := svc.UpdateRecord(ctx, other, 1, AgentRecordUpdate{LogAppend: "bad"}); err == nil {
@@ -125,6 +144,157 @@ func TestAgentServicePooledTaskUsesRecordNodeForSpecAndRecordUpdates(t *testing.
 	}
 }

+func TestAgentServiceRelaysRemoteArtifactToMasterLocalDisk(t *testing.T) {
+	svc, _, records, _, owner, other := newAgentServicePoolTestHarness(t)
+	ctx := context.Background()
+	payload := []byte("artifact from remote source server")
+	digest := sha256.Sum256(payload)
+	checksum := fmt.Sprintf("%x", digest[:])
+	record, err := records.FindByID(ctx, 1)
+	if err != nil {
+		t.Fatalf("FindByID record returned error: %v", err)
+	}
+	objectKey := backup.BuildRecordStorageKey("file", record.StartedAt, record.ID, "remote-source.tar")
+
+	if err := svc.UploadArtifact(ctx, owner, 1, 1, objectKey, int64(len(payload)), checksum, bytes.NewReader(payload)); err != nil {
+		t.Fatalf("UploadArtifact returned error: %v", err)
+	}
+	target, err := svc.storageRepo.FindByID(ctx, 1)
+	if err != nil || target == nil {
+		t.Fatalf("FindByID target: target=%#v err=%v", target, err)
+	}
+	config := map[string]any{}
+	if err := svc.cipher.DecryptJSON(target.ConfigCiphertext, &config); err != nil {
+		t.Fatalf("DecryptJSON target config: %v", err)
+	}
+	basePath, _ := config["basePath"].(string)
+	stored, err := os.ReadFile(filepath.Join(basePath, filepath.FromSlash(objectKey)))
+	if err != nil {
+		t.Fatalf("read relayed artifact: %v", err)
+	}
+	if !bytes.Equal(stored, payload) {
+		t.Fatalf("relayed artifact differs: got %q", stored)
+	}
+	if err := svc.UploadArtifact(ctx, other, 1, 1, objectKey, int64(len(payload)), checksum, bytes.NewReader(payload)); err == nil {
+		t.Fatal("expected a different node to be forbidden from relaying the artifact")
+	}
+
+	legacyPayload := []byte("artifact from an older Agent")
+	legacyDigest := sha256.Sum256(legacyPayload)
+	legacyKey := backup.BuildStorageKey("file", record.StartedAt, "legacy-agent.tar")
+	canonicalKey := backup.BuildRecordStorageKey("file", record.StartedAt, record.ID, "legacy-agent.tar")
+	if err := svc.UploadArtifact(ctx, owner, record.ID, target.ID, legacyKey, int64(len(legacyPayload)), fmt.Sprintf("%x", legacyDigest[:]), bytes.NewReader(legacyPayload)); err != nil {
+		t.Fatalf("UploadArtifact legacy key returned error: %v", err)
+	}
+	stored, err = os.ReadFile(filepath.Join(basePath, filepath.FromSlash(canonicalKey)))
+	if err != nil || !bytes.Equal(stored, legacyPayload) {
+		t.Fatalf("legacy Agent artifact was not normalized: data=%q err=%v", stored, err)
+	}
+	if _, err := os.Stat(filepath.Join(basePath, filepath.FromSlash(legacyKey))); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("legacy object key should not be written directly: %v", err)
+	}
+	if err := svc.UpdateRecord(ctx, owner, record.ID, AgentRecordUpdate{
+		Status:          model.BackupRecordStatusSuccess,
+		FileName:        "legacy-agent.tar",
+		FileSize:        int64(len(legacyPayload)),
+		Checksum:        fmt.Sprintf("%x", legacyDigest[:]),
+		StoragePath:     legacyKey,
+		StorageTargetID: target.ID,
+		StorageUploadResults: []StorageUploadResultItem{{
+			StorageTargetID: target.ID,
+			Status:          "success",
+			StoragePath:     legacyKey,
+			FileSize:        int64(len(legacyPayload)),
+		}},
+	}); err != nil {
+		t.Fatalf("UpdateRecord legacy key returned error: %v", err)
+	}
+	updated, err := records.FindByID(ctx, record.ID)
+	if err != nil {
+		t.Fatalf("FindByID updated record returned error: %v", err)
+	}
+	if updated.StoragePath != canonicalKey || updated.StorageTransferMode != storage.TransferModeMasterRelay || !strings.Contains(updated.StorageUploadResults, canonicalKey) {
+		t.Fatalf("legacy Agent record was not normalized: %#v", updated)
+	}
+}
+
+func TestAgentServiceRejectsArtifactOutsideRecordNamespace(t *testing.T) {
+	svc, _, records, _, owner, _ := newAgentServicePoolTestHarness(t)
+	ctx := context.Background()
+	record, err := records.FindByID(ctx, 1)
+	if err != nil {
+		t.Fatalf("FindByID record returned error: %v", err)
+	}
+	target, err := svc.storageRepo.FindByID(ctx, 1)
+	if err != nil || target == nil {
+		t.Fatalf("FindByID target: target=%#v err=%v", target, err)
+	}
+	config := map[string]any{}
+	if err := svc.cipher.DecryptJSON(target.ConfigCiphertext, &config); err != nil {
+		t.Fatalf("DecryptJSON target config: %v", err)
+	}
+	basePath, _ := config["basePath"].(string)
+	victimKey := backup.BuildRecordStorageKey("file", record.StartedAt, record.ID+1, "victim.tar")
+	victimPath := filepath.Join(basePath, filepath.FromSlash(victimKey))
+	if err := os.MkdirAll(filepath.Dir(victimPath), 0o755); err != nil {
+		t.Fatalf("MkdirAll victim parent: %v", err)
+	}
+	if err := os.WriteFile(victimPath, []byte("keep me"), 0o600); err != nil {
+		t.Fatalf("WriteFile victim: %v", err)
+	}
+	payload := []byte("overwrite")
+	digest := sha256.Sum256(payload)
+	if err := svc.UploadArtifact(ctx, owner, record.ID, target.ID, victimKey, int64(len(payload)), fmt.Sprintf("%x", digest[:]), bytes.NewReader(payload)); err == nil {
+		t.Fatal("expected another record namespace to be rejected")
+	}
+	stored, err := os.ReadFile(victimPath)
+	if err != nil {
+		t.Fatalf("ReadFile victim: %v", err)
+	}
+	if string(stored) != "keep me" {
+		t.Fatalf("victim object changed: %q", stored)
+	}
+	if err := svc.UpdateRecord(ctx, owner, record.ID, AgentRecordUpdate{StoragePath: victimKey, StorageTargetID: target.ID, StorageTransferMode: storage.TransferModeMasterRelay}); err == nil {
+		t.Fatal("expected another record namespace in status update to be rejected")
+	}
+}
+
+func TestAgentServiceKeepsExistingLocalDiskTargetsAgentLocal(t *testing.T) {
+	svc, _, records, _, owner, _ := newAgentServicePoolTestHarness(t)
+	ctx := context.Background()
+	target, err := svc.storageRepo.FindByID(ctx, 1)
+	if err != nil || target == nil {
+		t.Fatalf("FindByID target: target=%#v err=%v", target, err)
+	}
+	legacyConfig, err := svc.cipher.EncryptJSON(map[string]any{"basePath": t.TempDir()})
+	if err != nil {
+		t.Fatalf("EncryptJSON legacy target: %v", err)
+	}
+	target.ConfigCiphertext = legacyConfig
+	if err := svc.storageRepo.Update(ctx, target); err != nil {
+		t.Fatalf("Update legacy target: %v", err)
+	}
+
+	spec, err := svc.GetTaskSpec(ctx, owner, 1)
+	if err != nil {
+		t.Fatalf("GetTaskSpec returned error: %v", err)
+	}
+	if len(spec.StorageTargets) != 1 || spec.StorageTargets[0].TransferMode != storage.TransferModeDirect {
+		t.Fatalf("expected legacy local disk to stay Agent-local, got %#v", spec.StorageTargets)
+	}
+	payload := []byte("must not be relayed")
+	digest := sha256.Sum256(payload)
+	record, findErr := records.FindByID(ctx, 1)
+	if findErr != nil {
+		t.Fatalf("FindByID record returned error: %v", findErr)
+	}
+	objectKey := backup.BuildRecordStorageKey("file", record.StartedAt, record.ID, "legacy.tar")
+	err = svc.UploadArtifact(ctx, owner, 1, 1, objectKey, int64(len(payload)), fmt.Sprintf("%x", digest[:]), bytes.NewReader(payload))
+	if err == nil {
+		t.Fatal("expected relay upload to be rejected for an Agent-local target")
+	}
+}
+
 func TestAgentServiceUpdateRecordRefreshesTaskSummaryOnTerminalStatus(t *testing.T) {
 	for _, status := range []string{model.BackupRecordStatusSuccess, model.BackupRecordStatusFailed} {
 		t.Run(status, func(t *testing.T) {
--- a/server/internal/service/backup_execution_service.go
+++ b/server/internal/service/backup_execution_service.go
@@ -5,11 +5,13 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"hash"
 	"io"
 	"os"
 	"path/filepath"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -49,6 +51,7 @@ type StorageUploadResultItem struct {
 	Status            string `json:"status"`
 	StoragePath       string `json:"storagePath,omitempty"`
 	FileSize          int64  `json:"fileSize,omitempty"`
+	TransferMode      string `json:"transferMode,omitempty"`
 	Error             string `json:"error,omitempty"`
 }

@@ -62,6 +65,17 @@ type DownloadedArtifact struct {
 	Reader   io.ReadCloser
 }

+type temporaryArtifactReader struct {
+	*os.File
+	directory string
+}
+
+func (r *temporaryArtifactReader) Close() error {
+	closeErr := r.File.Close()
+	removeErr := os.RemoveAll(r.directory)
+	return errors.Join(closeErr, removeErr)
+}
+
 // collectTargetIDs 获取任务关联的所有存储目标 ID
 func collectTargetIDs(task *model.BackupTask) []uint {
 	if len(task.StorageTargets) > 0 {
@@ -102,6 +116,10 @@ type BackupExecutionService struct {
 	bandwidthLimit string // rclone 带宽限制（全局默认，节点配置可覆盖）
 	metrics        *metrics.Metrics
 	taskLocks      sync.Map
+	// repositoryLocks serializes immutable index updates per storage target.
+	// Repository mode is intentionally single-writer in v1 to avoid orphaned
+	// duplicate packs when two local tasks discover the same missing chunk.
+	repositoryLocks sync.Map
 }

 // SetMetrics 注入 Prometheus 采集器。nil 时所有埋点退化为 no-op。
@@ -211,6 +229,25 @@ func (s *BackupExecutionService) DownloadRecord(ctx context.Context, recordID ui
 	if err != nil {
 		return nil, err
 	}
+	if record.BackupKind == model.BackupKindRepository {
+		tempDir, err := os.MkdirTemp(s.tempDir, "repository-download-*")
+		if err != nil {
+			return nil, apperror.Internal("BACKUP_RECORD_DOWNLOAD_FAILED", "无法创建 CDC 导出目录", err)
+		}
+		exportName := fmt.Sprintf("backupx-record-%d.tar", record.ID)
+		exportPath := filepath.Join(tempDir, exportName)
+		store := backup.NewRepositoryStore(s.cipher.Key())
+		if err := store.ExportTar(ctx, provider, record.StoragePath, record.Checksum, exportPath); err != nil {
+			cleanupErr := os.RemoveAll(tempDir)
+			return nil, apperror.Internal("BACKUP_RECORD_DOWNLOAD_FAILED", "无法从 CDC 仓库导出归档", errors.Join(err, cleanupErr))
+		}
+		file, err := os.Open(exportPath)
+		if err != nil {
+			cleanupErr := os.RemoveAll(tempDir)
+			return nil, apperror.Internal("BACKUP_RECORD_DOWNLOAD_FAILED", "无法打开 CDC 导出归档", errors.Join(err, cleanupErr))
+		}
+		return &DownloadedArtifact{FileName: exportName, Reader: &temporaryArtifactReader{File: file, directory: tempDir}}, nil
+	}
 	reader, err := provider.Download(ctx, record.StoragePath)
 	if err != nil {
 		return nil, apperror.Internal("BACKUP_RECORD_DOWNLOAD_FAILED", "无法下载备份文件", err)
@@ -234,6 +271,16 @@ func (s *BackupExecutionService) RestoreRecord(ctx context.Context, recordID uin
 	if task == nil {
 		return apperror.New(404, "BACKUP_TASK_NOT_FOUND", "关联的备份任务不存在，无法执行恢复", fmt.Errorf("backup task %d not found", record.TaskID))
 	}
+	if record.BackupKind == model.BackupKindRepository {
+		spec, specErr := s.buildTaskSpec(task, record.StartedAt)
+		if specErr != nil {
+			return specErr
+		}
+		if err := backup.NewRepositoryStore(s.cipher.Key()).Restore(ctx, provider, record.StoragePath, record.Checksum, spec, backup.NopLogWriter{}); err != nil {
+			return apperror.Internal("BACKUP_RECORD_RESTORE_FAILED", "从 CDC 仓库恢复备份失败", err)
+		}
+		return nil
+	}
 	tempDir, err := os.MkdirTemp("", "backupx-restore-*")
 	if err != nil {
 		return apperror.Internal("BACKUP_RECORD_RESTORE_FAILED", "无法创建恢复目录", err)
@@ -291,6 +338,58 @@ func (s *BackupExecutionService) DeleteRecord(ctx context.Context, recordID uint
 				fmt.Sprintf("该全量备份仍有 %d 个差异备份依赖它，删除会导致这些差异无法恢复。请先删除相关差异备份或等待其过期。", deps), nil)
 		}
 	}
+	if record.BackupKind == model.BackupKindRepository {
+		copies := []StorageUploadResultItem{{
+			StorageTargetID: record.StorageTargetID,
+			Status:          model.BackupRecordStatusSuccess,
+			StoragePath:     record.StoragePath,
+		}}
+		if strings.TrimSpace(record.StorageUploadResults) != "" {
+			if err := json.Unmarshal([]byte(record.StorageUploadResults), &copies); err != nil {
+				return apperror.Internal("BACKUP_RECORD_DELETE_FAILED", "无法解析 CDC 仓库副本信息，已停止删除以避免遗留数据", err)
+			}
+		}
+		copyPaths := make(map[uint]string, len(copies))
+		for _, copy := range copies {
+			if strings.EqualFold(copy.Status, model.BackupRecordStatusSuccess) && strings.TrimSpace(copy.StoragePath) != "" {
+				copyPaths[copy.StorageTargetID] = copy.StoragePath
+			}
+		}
+		targetIDs := make([]uint, 0, len(copyPaths))
+		for targetID := range copyPaths {
+			targetIDs = append(targetIDs, targetID)
+		}
+		sort.Slice(targetIDs, func(i, j int) bool { return targetIDs[i] < targetIDs[j] })
+		unlocks := make([]func(), 0, len(targetIDs))
+		for _, targetID := range targetIDs {
+			unlocks = append(unlocks, s.acquireRepositoryLock(targetID))
+		}
+		defer func() {
+			for index := len(unlocks) - 1; index >= 0; index-- {
+				unlocks[index]()
+			}
+		}()
+		providers := make(map[uint]storage.StorageProvider, len(targetIDs))
+		for _, targetID := range targetIDs {
+			provider, resolveErr := s.resolveProvider(ctx, targetID)
+			if resolveErr != nil {
+				return resolveErr
+			}
+			if deleteErr := provider.Delete(ctx, copyPaths[targetID]); deleteErr != nil {
+				return apperror.Internal("BACKUP_RECORD_DELETE_FAILED", "无法删除 CDC 仓库快照", deleteErr)
+			}
+			providers[targetID] = provider
+		}
+		for targetID, provider := range providers {
+			if _, pruneErr := backup.NewRepositoryStore(s.cipher.Key()).Prune(ctx, provider); pruneErr != nil {
+				return apperror.Internal("BACKUP_REPOSITORY_PRUNE_FAILED", fmt.Sprintf("无法清理存储目标 %d 的 CDC 仓库；记录暂时保留以便重试", targetID), pruneErr)
+			}
+		}
+		if err := s.records.Delete(ctx, recordID); err != nil {
+			return apperror.Internal("BACKUP_RECORD_DELETE_FAILED", "无法删除备份记录", err)
+		}
+		return nil
+	}
 	if remote, err := s.deleteRemoteLocalDiskObject(ctx, record); err != nil {
 		return err
 	} else if !remote && strings.TrimSpace(record.StoragePath) != "" {
@@ -312,6 +411,9 @@ func (s *BackupExecutionService) deleteRemoteLocalDiskObject(ctx context.Context
 	if strings.TrimSpace(record.StoragePath) == "" || s.nodeRepo == nil {
 		return false, nil
 	}
+	if record.StorageTransferMode == storage.TransferModeMasterRelay {
+		return false, nil
+	}
 	node, err := s.nodeRepo.FindByID(ctx, record.NodeID)
 	if err != nil || node == nil || node.IsLocal {
 		return false, nil
@@ -384,6 +486,9 @@ func (s *BackupExecutionService) startTask(ctx context.Context, id uint, async b
 			return nil, perr
 		}
 	}
+	if strings.EqualFold(task.BackupMode, model.BackupModeRepository) && s.resolveRemoteNode(ctx, resolvedNodeID) != nil {
+		return nil, apperror.BadRequest("BACKUP_TASK_REPOSITORY_REMOTE_UNSUPPORTED", "CDC 仓库模式当前仅支持 Master 本机单写者执行", nil)
+	}
 	startedAt := s.now()
 	// 取第一个存储目标 ID 做兼容
 	primaryTargetID := task.StorageTargetID
@@ -630,6 +735,141 @@ func (s *BackupExecutionService) resolveDifferentialBase(ctx context.Context, ta
 	return 0, backup.Manifest{}, false
 }

+type repositoryTaskResult struct {
+	fileName        string
+	logicalSize     int64
+	checksum        string
+	storagePath     string
+	storageTargetID uint
+	manifestJSON    string
+	uploadResults   []StorageUploadResultItem
+	providers       map[uint]storage.StorageProvider
+}
+
+func (s *BackupExecutionService) executeRepositoryTask(ctx context.Context, task *model.BackupTask, recordID uint, startedAt time.Time, spec backup.TaskSpec, logger *backup.ExecutionLogger) (*repositoryTaskResult, error) {
+	store := backup.NewRepositoryStore(s.cipher.Key())
+	plan, err := store.BuildPlan(ctx, spec, logger)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if closeErr := plan.Close(); closeErr != nil {
+			logger.Warnf("清理 CDC 临时计划失败：%v", closeErr)
+		}
+	}()
+	manifestBytes, err := backup.EncodeManifest(plan.Manifest)
+	if err != nil {
+		return nil, fmt.Errorf("encode repository manifest: %w", err)
+	}
+	targetIDs := collectTargetIDs(task)
+	if len(targetIDs) == 0 {
+		return nil, fmt.Errorf("没有关联的存储目标")
+	}
+	storageUsage, usageErr := s.storageUsageSnapshot(ctx)
+	if usageErr != nil {
+		logger.Warnf("读取存储目标用量失败，跳过本次软配额校验：%v", usageErr)
+		storageUsage = map[uint]int64{}
+	}
+
+	snapshotKey := store.SnapshotKey(task.ID, recordID, startedAt)
+	result := &repositoryTaskResult{
+		fileName:      filepath.Base(snapshotKey),
+		logicalSize:   plan.LogicalSize,
+		storagePath:   snapshotKey,
+		manifestJSON:  string(manifestBytes),
+		uploadResults: make([]StorageUploadResultItem, 0, len(targetIDs)),
+		providers:     make(map[uint]storage.StorageProvider),
+	}
+	var failures []string
+	for _, targetID := range targetIDs {
+		target, findErr := s.targets.FindByID(ctx, targetID)
+		targetName := fmt.Sprintf("target-%d", targetID)
+		if findErr == nil && target != nil {
+			targetName = target.Name
+		}
+		if findErr != nil || target == nil {
+			message := "存储目标不存在"
+			if findErr != nil {
+				message = findErr.Error()
+			}
+			result.uploadResults = append(result.uploadResults, StorageUploadResultItem{StorageTargetID: targetID, StorageTargetName: targetName, Status: "failed", Error: message})
+			failures = append(failures, fmt.Sprintf("%s: %s", targetName, message))
+			continue
+		}
+		provider, resolveErr := s.resolveProviderForNode(ctx, targetID, task.NodeID)
+		if resolveErr != nil {
+			result.uploadResults = append(result.uploadResults, StorageUploadResultItem{StorageTargetID: targetID, StorageTargetName: targetName, Status: "failed", Error: resolveErr.Error()})
+			failures = append(failures, fmt.Sprintf("%s: %v", targetName, resolveErr))
+			continue
+		}
+		logger.Infof("同步 CDC 仓库到存储目标：%s", targetName)
+		unlock := s.acquireRepositoryLock(targetID)
+		estimatedSize, estimateErr := store.EstimateUploadSize(ctx, provider, plan)
+		if estimateErr != nil {
+			unlock()
+			result.uploadResults = append(result.uploadResults, StorageUploadResultItem{StorageTargetID: targetID, StorageTargetName: targetName, Status: "failed", Error: estimateErr.Error()})
+			failures = append(failures, fmt.Sprintf("%s: %v", targetName, estimateErr))
+			continue
+		}
+		if target.QuotaBytes > 0 && storageUsage[targetID]+estimatedSize > target.QuotaBytes {
+			unlock()
+			message := fmt.Sprintf("超出存储目标配额（%d + 预计 %d > %d）", storageUsage[targetID], estimatedSize, target.QuotaBytes)
+			result.uploadResults = append(result.uploadResults, StorageUploadResultItem{StorageTargetID: targetID, StorageTargetName: targetName, Status: "failed", Error: message})
+			failures = append(failures, fmt.Sprintf("%s: %s", targetName, message))
+			continue
+		}
+		upload, uploadErr := store.Upload(ctx, provider, plan, snapshotKey)
+		unlock()
+		if uploadErr != nil {
+			result.uploadResults = append(result.uploadResults, StorageUploadResultItem{StorageTargetID: targetID, StorageTargetName: targetName, Status: "failed", Error: uploadErr.Error()})
+			failures = append(failures, fmt.Sprintf("%s: %v", targetName, uploadErr))
+			logger.Warnf("存储目标 %s CDC 仓库同步失败：%v", targetName, uploadErr)
+			continue
+		}
+		result.uploadResults = append(result.uploadResults, StorageUploadResultItem{
+			StorageTargetID: targetID, StorageTargetName: targetName, Status: "success",
+			StoragePath: upload.SnapshotKey, FileSize: upload.UploadedBytes,
+		})
+		result.providers[targetID] = provider
+		if result.storageTargetID == 0 {
+			result.storageTargetID = targetID
+			result.checksum = upload.Checksum
+		}
+		logger.Infof("存储目标 %s CDC 同步完成：新块 %d/%d，复用 %d bytes，实际上传 %d bytes", targetName, upload.NewChunks, upload.UniqueChunks, upload.ReusedBytes, upload.UploadedBytes)
+	}
+	if result.storageTargetID == 0 {
+		return nil, fmt.Errorf("所有存储目标 CDC 仓库同步均失败：%s", strings.Join(failures, "; "))
+	}
+	if len(failures) > 0 {
+		logger.Warnf("部分存储目标 CDC 仓库同步失败：%s", strings.Join(failures, "; "))
+	}
+	if s.dependentsResolver != nil {
+		go func(upstreamID uint, upstreamName string) {
+			dependents, resolveErr := s.dependentsResolver.TriggerDependents(context.Background(), upstreamID)
+			if resolveErr != nil {
+				logger.Warnf("解析任务 %s 的下游依赖失败：%v", upstreamName, resolveErr)
+				return
+			}
+			for _, dependentID := range dependents {
+				if _, runErr := s.RunTaskByID(context.Background(), dependentID); runErr != nil {
+					logger.Warnf("触发下游任务 #%d 失败（上游: %s）：%v", dependentID, upstreamName, runErr)
+				} else {
+					logger.Infof("已触发下游任务 #%d（上游: %s）", dependentID, upstreamName)
+				}
+			}
+		}(task.ID, task.Name)
+	}
+	return result, nil
+}
+
+func (s *BackupExecutionService) acquireRepositoryLock(targetID uint) func() {
+	created := &sync.Mutex{}
+	actual, _ := s.repositoryLocks.LoadOrStore(targetID, created)
+	lock := actual.(*sync.Mutex)
+	lock.Lock()
+	return lock.Unlock
+}
+
 func (s *BackupExecutionService) executeTask(ctx context.Context, task *model.BackupTask, recordID uint, startedAt time.Time) {
 	// 节点级并发限流：当任务绑定节点且节点配置了 MaxConcurrent>0，
 	// 该节点上所有任务共享一个节点专属 semaphore，互相排队
@@ -658,18 +898,33 @@ func (s *BackupExecutionService) executeTask(ctx context.Context, task *model.Ba
 	backupKind := model.BackupKindFull
 	var baseRecordID uint
 	var manifestJSON string
+	var repositoryProviders map[uint]storage.StorageProvider
 	completeRecord := func() {
+		readyForRepositoryRetention := status == model.BackupRecordStatusSuccess
 		if finalizeErr := s.finalizeRecord(ctx, task, recordID, startedAt, status, errMessage, logger.String(), fileName, fileSize, checksum, storagePath, selectedStorageTargetID); finalizeErr != nil {
 			logger.Errorf("写回备份记录失败：%v", finalizeErr)
+			readyForRepositoryRetention = false
 		}
 		// 采集任务执行结果到 Prometheus（耗时 + 产出字节 + 状态计数）
 		s.metrics.ObserveTaskRun(task.Type, status, time.Since(startedAt).Seconds(), fileSize)
 		// 写入多目标上传结果
 		if len(uploadResults) > 0 {
-			if resultsJSON, marshalErr := json.Marshal(uploadResults); marshalErr == nil {
-				if record, findErr := s.records.FindByID(ctx, recordID); findErr == nil && record != nil {
-					record.StorageUploadResults = string(resultsJSON)
-					_ = s.records.Update(ctx, record)
+			resultsJSON, marshalErr := json.Marshal(uploadResults)
+			if marshalErr != nil {
+				logger.Warnf("序列化多目标上传结果失败：%v", marshalErr)
+				readyForRepositoryRetention = false
+			} else if record, findErr := s.records.FindByID(ctx, recordID); findErr != nil || record == nil {
+				if findErr != nil {
+					logger.Warnf("读取备份记录以写回多目标结果失败：%v", findErr)
+				} else {
+					logger.Warnf("备份记录 #%d 不存在，无法写回多目标结果", recordID)
+				}
+				readyForRepositoryRetention = false
+			} else {
+				record.StorageUploadResults = string(resultsJSON)
+				if updateErr := s.records.Update(ctx, record); updateErr != nil {
+					logger.Warnf("写回多目标上传结果失败：%v", updateErr)
+					readyForRepositoryRetention = false
 				}
 			}
 		}
@@ -681,6 +936,36 @@ func (s *BackupExecutionService) executeTask(ctx context.Context, task *model.Ba
 				record.Manifest = manifestJSON
 				if updErr := s.records.Update(ctx, record); updErr != nil {
 					logger.Warnf("写回差异链信息失败：%v", updErr)
+					readyForRepositoryRetention = false
+				}
+			} else {
+				if findErr != nil {
+					logger.Warnf("读取备份记录以写回备份类型失败：%v", findErr)
+				} else {
+					logger.Warnf("备份记录 #%d 不存在，无法写回备份类型", recordID)
+				}
+				readyForRepositoryRetention = false
+			}
+		}
+		if readyForRepositoryRetention && backupKind == model.BackupKindRepository && s.retention != nil && len(repositoryProviders) > 0 {
+			targetIDs := make([]uint, 0, len(repositoryProviders))
+			for targetID := range repositoryProviders {
+				targetIDs = append(targetIDs, targetID)
+			}
+			sort.Slice(targetIDs, func(i, j int) bool { return targetIDs[i] < targetIDs[j] })
+			unlocks := make([]func(), 0, len(targetIDs))
+			for _, targetID := range targetIDs {
+				unlocks = append(unlocks, s.acquireRepositoryLock(targetID))
+			}
+			cleanupResult, cleanupErr := s.retention.CleanupProviders(ctx, task, repositoryProviders)
+			for index := len(unlocks) - 1; index >= 0; index-- {
+				unlocks[index]()
+			}
+			if cleanupErr != nil {
+				logger.Warnf("执行 CDC 仓库保留策略失败：%v", cleanupErr)
+			} else {
+				for _, warning := range cleanupResult.Warnings {
+					logger.Warnf("CDC 仓库保留策略警告：%s", warning)
 				}
 			}
 		}
@@ -701,6 +986,26 @@ func (s *BackupExecutionService) executeTask(ctx context.Context, task *model.Ba
 		logger.Errorf("构建任务运行时配置失败：%v", err)
 		return
 	}
+	if task.Type == model.BackupTaskTypeFile && strings.EqualFold(task.BackupMode, model.BackupModeRepository) {
+		backupKind = model.BackupKindRepository
+		repositoryResult, repositoryErr := s.executeRepositoryTask(ctx, task, recordID, startedAt, spec, logger)
+		if repositoryErr != nil {
+			errMessage = repositoryErr.Error()
+			logger.Errorf("执行 CDC 仓库备份失败：%v", repositoryErr)
+			return
+		}
+		fileName = repositoryResult.fileName
+		fileSize = repositoryResult.logicalSize
+		checksum = repositoryResult.checksum
+		storagePath = repositoryResult.storagePath
+		selectedStorageTargetID = repositoryResult.storageTargetID
+		uploadResults = repositoryResult.uploadResults
+		repositoryProviders = repositoryResult.providers
+		manifestJSON = repositoryResult.manifestJSON
+		status = model.BackupRecordStatusSuccess
+		logger.Infof("CDC 仓库备份执行完成")
+		return
+	}
 	// 差异备份：解析基线全量，命中则切换为差异模式（仅本机文件任务）。
 	if baseID, baseManifest, ok := s.resolveDifferentialBase(ctx, task); ok {
 		spec.Differential = true
--- a/server/internal/service/backup_execution_service_test.go
+++ b/server/internal/service/backup_execution_service_test.go
@@ -1,6 +1,7 @@
 package service

 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -155,6 +156,108 @@ func TestBackupExecutionServiceRunTaskByIDSync(t *testing.T) {
 	}
 }

+func TestBackupExecutionServiceRepositoryModeRoundTrip(t *testing.T) {
+	executionService, recordService, tasks, _, records, sourceDir, storageDir := newExecutionTestServices(t)
+	ctx := context.Background()
+	task, err := tasks.FindByID(ctx, 1)
+	if err != nil {
+		t.Fatalf("FindByID task returned error: %v", err)
+	}
+	task.BackupMode = model.BackupModeRepository
+	task.Compression = "zstd"
+	if err := tasks.Update(ctx, task); err != nil {
+		t.Fatalf("Update repository task returned error: %v", err)
+	}
+	large := make([]byte, 4<<20)
+	for index := range large {
+		large[index] = byte((index * 31) % 251)
+	}
+	largePath := filepath.Join(sourceDir, "large.bin")
+	if err := os.WriteFile(largePath, large, 0o640); err != nil {
+		t.Fatalf("write large fixture: %v", err)
+	}
+
+	first, err := executionService.RunTaskByIDSync(ctx, task.ID)
+	if err != nil {
+		t.Fatalf("first repository backup returned error: %v", err)
+	}
+	if first.Status != model.BackupRecordStatusSuccess || first.BackupKind != model.BackupKindRepository {
+		t.Fatalf("unexpected first repository record: %#v", first)
+	}
+	if !strings.HasPrefix(first.StoragePath, ".backupx/repository/v1/snapshots/") {
+		t.Fatalf("unexpected repository snapshot path: %s", first.StoragePath)
+	}
+
+	large[2<<20] ^= 0xff
+	if err := os.WriteFile(largePath, large, 0o640); err != nil {
+		t.Fatalf("modify large fixture: %v", err)
+	}
+	second, err := executionService.RunTaskByIDSync(ctx, task.ID)
+	if err != nil {
+		t.Fatalf("second repository backup returned error: %v", err)
+	}
+	stored, err := records.FindByID(ctx, second.ID)
+	if err != nil {
+		t.Fatalf("FindByID repository record returned error: %v", err)
+	}
+	if stored == nil || stored.BackupKind != model.BackupKindRepository || stored.Manifest == "" {
+		t.Fatalf("repository metadata was not persisted: %#v", stored)
+	}
+
+	download, err := recordService.Download(ctx, second.ID)
+	if err != nil {
+		t.Fatalf("export repository snapshot returned error: %v", err)
+	}
+	exported, readErr := io.ReadAll(download.Reader)
+	closeErr := download.Reader.Close()
+	if readErr != nil || closeErr != nil {
+		t.Fatalf("read repository export: read=%v close=%v", readErr, closeErr)
+	}
+	if len(exported) == 0 || !strings.HasSuffix(download.FileName, ".tar") {
+		t.Fatalf("unexpected repository export: name=%s size=%d", download.FileName, len(exported))
+	}
+
+	if err := os.WriteFile(largePath, bytes.Repeat([]byte{0}, len(large)), 0o640); err != nil {
+		t.Fatalf("damage source before restore: %v", err)
+	}
+	if err := executionService.RestoreRecord(ctx, second.ID); err != nil {
+		t.Fatalf("restore repository record returned error: %v", err)
+	}
+	restored, err := os.ReadFile(largePath)
+	if err != nil {
+		t.Fatalf("read restored source: %v", err)
+	}
+	if !bytes.Equal(restored, large) {
+		t.Fatalf("repository restore did not reproduce the source")
+	}
+
+	if err := recordService.Delete(ctx, first.ID); err != nil {
+		t.Fatalf("delete first repository record: %v", err)
+	}
+	if err := recordService.Delete(ctx, second.ID); err != nil {
+		t.Fatalf("delete second repository record: %v", err)
+	}
+	packRoot := filepath.Join(storageDir, filepath.FromSlash(".backupx/repository/v1/packs"))
+	remainingPacks := 0
+	if err := filepath.Walk(packRoot, func(_ string, info os.FileInfo, walkErr error) error {
+		if walkErr != nil {
+			if os.IsNotExist(walkErr) {
+				return nil
+			}
+			return walkErr
+		}
+		if info != nil && !info.IsDir() {
+			remainingPacks++
+		}
+		return nil
+	}); err != nil {
+		t.Fatalf("inspect repository packs: %v", err)
+	}
+	if remainingPacks != 0 {
+		t.Fatalf("repository prune left %d packs after deleting all snapshots", remainingPacks)
+	}
+}
+
 func TestBackupExecutionServiceNodePoolSelectionDoesNotPersistTaskNodeID(t *testing.T) {
 	executionService, _, tasks, _, records, _, _ := newExecutionTestServices(t)
 	ctx := context.Background()
@@ -326,6 +429,56 @@ func TestBackupExecutionServiceRestoreRecordRejectsRemoteLocalDisk(t *testing.T)
 	}
 }

+func TestBackupExecutionServiceDownloadsMasterRelayedLocalDiskRecord(t *testing.T) {
+	executionService, _, tasks, _, records, _, storageDir := newExecutionTestServices(t)
+	ctx := context.Background()
+	executionService.SetClusterDependencies(&nodeRepoStub{nodes: []model.Node{
+		{ID: 10, Name: "edge-a", Token: "edge-a-token", Status: model.NodeStatusOnline},
+	}}, &fakeDispatcher{})
+	task, err := tasks.FindByID(ctx, 1)
+	if err != nil {
+		t.Fatalf("FindByID task returned error: %v", err)
+	}
+	storagePath := "file/2026/05/09/relayed.tar"
+	artifactPath := filepath.Join(storageDir, filepath.FromSlash(storagePath))
+	if err := os.MkdirAll(filepath.Dir(artifactPath), 0o755); err != nil {
+		t.Fatalf("MkdirAll artifact parent returned error: %v", err)
+	}
+	content := []byte("stored on Master")
+	if err := os.WriteFile(artifactPath, content, 0o600); err != nil {
+		t.Fatalf("WriteFile artifact returned error: %v", err)
+	}
+	completedAt := time.Now().UTC()
+	record := &model.BackupRecord{
+		TaskID:              task.ID,
+		StorageTargetID:     task.StorageTargetID,
+		NodeID:              10,
+		Status:              model.BackupRecordStatusSuccess,
+		FileName:            "relayed.tar",
+		FileSize:            int64(len(content)),
+		StoragePath:         storagePath,
+		StorageTransferMode: storage.TransferModeMasterRelay,
+		StartedAt:           completedAt.Add(-time.Second),
+		CompletedAt:         &completedAt,
+	}
+	if err := records.Create(ctx, record); err != nil {
+		t.Fatalf("Create record returned error: %v", err)
+	}
+
+	download, err := executionService.DownloadRecord(ctx, record.ID)
+	if err != nil {
+		t.Fatalf("DownloadRecord returned error: %v", err)
+	}
+	got, readErr := io.ReadAll(download.Reader)
+	closeErr := download.Reader.Close()
+	if readErr != nil || closeErr != nil {
+		t.Fatalf("read relayed artifact: read=%v close=%v", readErr, closeErr)
+	}
+	if !bytes.Equal(got, content) {
+		t.Fatalf("downloaded content = %q, want %q", got, content)
+	}
+}
+
 func TestBackupExecutionServiceRecordsFirstSuccessfulStorageTarget(t *testing.T) {
 	executionService, _, tasks, targets, records, _, _ := newExecutionTestServices(t)
 	ctx := context.Background()
--- a/server/internal/service/backup_record_service.go
+++ b/server/internal/service/backup_record_service.go
@@ -23,22 +23,23 @@ type BackupRecordListInput struct {
 }

 type BackupRecordSummary struct {
-	ID                uint       `json:"id"`
-	TaskID            uint       `json:"taskId"`
-	TaskName          string     `json:"taskName"`
-	StorageTargetID   uint       `json:"storageTargetId"`
-	StorageTargetName string     `json:"storageTargetName"`
-	Status            string     `json:"status"`
-	FileName          string     `json:"fileName"`
-	FileSize          int64      `json:"fileSize"`
-	Checksum          string     `json:"checksum"`
-	StoragePath       string     `json:"storagePath"`
-	DurationSeconds   int        `json:"durationSeconds"`
-	ErrorMessage      string     `json:"errorMessage"`
-	StartedAt         time.Time  `json:"startedAt"`
-	CompletedAt       *time.Time `json:"completedAt,omitempty"`
-	Locked            bool       `json:"locked"`
-	BackupKind        string     `json:"backupKind"`
+	ID                  uint       `json:"id"`
+	TaskID              uint       `json:"taskId"`
+	TaskName            string     `json:"taskName"`
+	StorageTargetID     uint       `json:"storageTargetId"`
+	StorageTargetName   string     `json:"storageTargetName"`
+	Status              string     `json:"status"`
+	FileName            string     `json:"fileName"`
+	FileSize            int64      `json:"fileSize"`
+	Checksum            string     `json:"checksum"`
+	StoragePath         string     `json:"storagePath"`
+	StorageTransferMode string     `json:"storageTransferMode,omitempty"`
+	DurationSeconds     int        `json:"durationSeconds"`
+	ErrorMessage        string     `json:"errorMessage"`
+	StartedAt           time.Time  `json:"startedAt"`
+	CompletedAt         *time.Time `json:"completedAt,omitempty"`
+	Locked              bool       `json:"locked"`
+	BackupKind          string     `json:"backupKind"`
 }

 type BackupRecordDetail struct {
@@ -184,22 +185,23 @@ func (s *BackupRecordService) SetLock(ctx context.Context, id uint, locked bool)

 func toBackupRecordSummary(item *model.BackupRecord) BackupRecordSummary {
 	return BackupRecordSummary{
-		ID:                item.ID,
-		TaskID:            item.TaskID,
-		TaskName:          item.Task.Name,
-		StorageTargetID:   item.StorageTargetID,
-		StorageTargetName: item.StorageTarget.Name,
-		Status:            item.Status,
-		FileName:          item.FileName,
-		FileSize:          item.FileSize,
-		Checksum:          item.Checksum,
-		StoragePath:       item.StoragePath,
-		DurationSeconds:   item.DurationSeconds,
-		ErrorMessage:      item.ErrorMessage,
-		StartedAt:         item.StartedAt,
-		CompletedAt:       item.CompletedAt,
-		Locked:            item.Locked,
-		BackupKind:        item.BackupKind,
+		ID:                  item.ID,
+		TaskID:              item.TaskID,
+		TaskName:            item.Task.Name,
+		StorageTargetID:     item.StorageTargetID,
+		StorageTargetName:   item.StorageTarget.Name,
+		Status:              item.Status,
+		FileName:            item.FileName,
+		FileSize:            item.FileSize,
+		Checksum:            item.Checksum,
+		StoragePath:         item.StoragePath,
+		StorageTransferMode: item.StorageTransferMode,
+		DurationSeconds:     item.DurationSeconds,
+		ErrorMessage:        item.ErrorMessage,
+		StartedAt:           item.StartedAt,
+		CompletedAt:         item.CompletedAt,
+		Locked:              item.Locked,
+		BackupKind:          item.BackupKind,
 	}
 }

--- a/server/internal/service/backup_task_service.go
+++ b/server/internal/service/backup_task_service.go
@@ -57,8 +57,8 @@ type BackupTaskUpsertInput struct {
 	KeepWeekly  int `json:"keepWeekly"`
 	KeepMonthly int `json:"keepMonthly"`
 	KeepYearly  int `json:"keepYearly"`
-	// BackupMode 备份模式：full（默认）/ differential（差异，仅文件类型本机任务）
-	BackupMode           string `json:"backupMode" binding:"omitempty,oneof=full differential"`
+	// BackupMode 备份模式：full（默认）/ differential（差异归档）/ repository（CDC 去重仓库）
+	BackupMode           string `json:"backupMode" binding:"omitempty,oneof=full differential repository"`
 	DiffFullIntervalDays int    `json:"diffFullIntervalDays"`
 	// 备份复制目标存储 ID 列表（3-2-1 规则）
 	ReplicationTargetIDs []uint `json:"replicationTargetIds"`
@@ -414,21 +414,50 @@ func (s *BackupTaskService) cleanupRemoteFiles(ctx context.Context, taskID uint)
 	recordCount = len(records)
 	// 缓存 provider 避免同一存储目标重复创建连接
 	providerCache := make(map[uint]storage.StorageProvider)
+	repositoryProviders := make(map[uint]storage.StorageProvider)
 	for _, record := range records {
-		if strings.TrimSpace(record.StoragePath) == "" {
-			continue
+		copies := []StorageUploadResultItem{{
+			StorageTargetID: record.StorageTargetID,
+			Status:          model.BackupRecordStatusSuccess,
+			StoragePath:     record.StoragePath,
+		}}
+		if strings.TrimSpace(record.StorageUploadResults) != "" {
+			var storedCopies []StorageUploadResultItem
+			if unmarshalErr := json.Unmarshal([]byte(record.StorageUploadResults), &storedCopies); unmarshalErr == nil {
+				copies = storedCopies
+			}
 		}
-		provider, ok := providerCache[record.StorageTargetID]
-		if !ok {
-			provider, err = s.resolveStorageProvider(ctx, record.StorageTargetID)
-			if err != nil {
+		seenTargets := make(map[uint]struct{}, len(copies))
+		for _, copy := range copies {
+			if !strings.EqualFold(copy.Status, model.BackupRecordStatusSuccess) || strings.TrimSpace(copy.StoragePath) == "" {
 				continue
 			}
-			providerCache[record.StorageTargetID] = provider
+			if _, seen := seenTargets[copy.StorageTargetID]; seen {
+				continue
+			}
+			seenTargets[copy.StorageTargetID] = struct{}{}
+			provider, ok := providerCache[copy.StorageTargetID]
+			if !ok {
+				provider, err = s.resolveStorageProvider(ctx, copy.StorageTargetID)
+				if err != nil {
+					continue
+				}
+				providerCache[copy.StorageTargetID] = provider
+			}
+			if err := provider.Delete(ctx, copy.StoragePath); err == nil {
+				cleanedFiles++
+				if record.BackupKind == model.BackupKindRepository {
+					repositoryProviders[copy.StorageTargetID] = provider
+				}
+			}
 		}
-		if err := provider.Delete(ctx, record.StoragePath); err == nil {
-			cleanedFiles++
+	}
+	for _, provider := range repositoryProviders {
+		pruned, pruneErr := backup.NewRepositoryStore(s.cipher.Key()).Prune(ctx, provider)
+		if pruneErr != nil {
+			continue
 		}
+		cleanedFiles += pruned.DeletedIndexes + pruned.DeletedPacks
 	}
 	return recordCount, cleanedFiles
 }
@@ -530,6 +559,17 @@ func (s *BackupTaskService) validateInput(ctx context.Context, existing *model.B
 			return apperror.BadRequest("BACKUP_TASK_DIFF_REMOTE_UNSUPPORTED", "差异备份当前仅支持本机 Master 执行，请将任务固定在本机或改用全量备份。", nil)
 		}
 	}
+	if strings.EqualFold(strings.TrimSpace(input.BackupMode), model.BackupModeRepository) {
+		if input.Type != model.BackupTaskTypeFile {
+			return apperror.BadRequest("BACKUP_TASK_REPOSITORY_UNSUPPORTED", "CDC 仓库模式仅支持文件目录类型任务", nil)
+		}
+		if strings.TrimSpace(input.NodePoolTag) != "" || (fixedNode != nil && !fixedNode.IsLocal) {
+			return apperror.BadRequest("BACKUP_TASK_REPOSITORY_REMOTE_UNSUPPORTED", "CDC 仓库模式当前采用单写者索引，仅支持 Master 本机执行。远程服务器备份请暂用全量模式。", nil)
+		}
+		if len(input.ReplicationTargetIDs) > 0 {
+			return apperror.BadRequest("BACKUP_TASK_REPOSITORY_REPLICATION_UNSUPPORTED", "CDC 仓库快照不能使用对象级复制；请直接为任务选择多个存储目标以生成完整仓库副本。", nil)
+		}
+	}
 	if input.RetentionDays < 0 {
 		return apperror.BadRequest("BACKUP_TASK_INVALID", "保留天数不能小于 0", nil)
 	}
@@ -935,10 +975,17 @@ func decodeExtraConfig(value string) (map[string]any, error) {
 	return result, nil
 }

-// normalizeBackupMode 归一化备份模式：仅文件类型可启用差异，其余一律全量（双保险，防绕过校验）。
+// normalizeBackupMode 归一化备份模式：仅文件类型可启用差异或 CDC 仓库，
+// 其余一律全量（双保险，防绕过校验）。
 func normalizeBackupMode(mode, taskType string) string {
-	if strings.EqualFold(strings.TrimSpace(mode), model.BackupModeDifferential) && normalizeBackupTaskType(taskType) == model.BackupTaskTypeFile {
+	if normalizeBackupTaskType(taskType) != model.BackupTaskTypeFile {
+		return model.BackupModeFull
+	}
+	switch strings.ToLower(strings.TrimSpace(mode)) {
+	case model.BackupModeDifferential:
 		return model.BackupModeDifferential
+	case model.BackupModeRepository:
+		return model.BackupModeRepository
 	}
 	return model.BackupModeFull
 }
--- a/server/internal/service/execution_helpers.go
+++ b/server/internal/service/execution_helpers.go
@@ -140,6 +140,11 @@ func validateCrossNodeLocalDisk(ctx context.Context, nodeRepo repository.NodeRep
 	if record == nil || record.NodeID == 0 || nodeRepo == nil {
 		return nil
 	}
+	// 中转模式的对象实际落在 Master 配置的本地磁盘，Master 可以安全访问。
+	// 空值和 direct 均按旧版 Agent 本地落盘处理，保持升级兼容。
+	if record.StorageTransferMode == storage.TransferModeMasterRelay {
+		return nil
+	}
 	node, err := nodeRepo.FindByID(ctx, record.NodeID)
 	if err != nil || node == nil || node.IsLocal {
 		return nil
--- a/server/internal/service/restore_service.go
+++ b/server/internal/service/restore_service.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -321,6 +322,13 @@ func (s *RestoreService) restoreArtifact(ctx context.Context, record *model.Back
 	if err != nil {
 		return fmt.Errorf("创建存储客户端失败：%w", err)
 	}
+	if record.BackupKind == model.BackupKindRepository {
+		logger.Infof("读取 CDC 仓库快照：%s", record.StoragePath)
+		if err := backup.NewRepositoryStore(s.cipher.Key()).Restore(ctx, provider, record.StoragePath, record.Checksum, spec, logger); err != nil {
+			return fmt.Errorf("恢复 CDC 仓库快照失败：%w", err)
+		}
+		return nil
+	}
 	recDir, err := os.MkdirTemp(parentTempDir, fmt.Sprintf("rec-%d-*", record.ID))
 	if err != nil {
 		return fmt.Errorf("创建恢复子目录失败：%w", err)
@@ -368,6 +376,9 @@ func (s *RestoreService) buildRestoreChain(ctx context.Context, record *model.Ba
 }

 func backupKindLabel(kind string) string {
+	if kind == model.BackupKindRepository {
+		return "CDC 仓库快照"
+	}
 	if kind == model.BackupKindDifferential {
 		return "差异"
 	}
@@ -591,15 +602,22 @@ func (s *RestoreService) GetAgentRestoreSpec(ctx context.Context, node *model.No
 	if target == nil {
 		return nil, apperror.BadRequest("BACKUP_STORAGE_TARGET_INVALID", "存储目标不存在", nil)
 	}
-	configRaw, err := s.cipher.Decrypt(target.ConfigCiphertext)
-	if err != nil {
-		return nil, fmt.Errorf("decrypt storage config: %w", err)
-	}
 	// 拆开 sourcePaths
 	sourcePaths := []string{}
 	if strings.TrimSpace(task.SourcePaths) != "" {
 		_ = json.Unmarshal([]byte(task.SourcePaths), &sourcePaths)
 	}
+	transferMode := storage.TransferModeDirect
+	if backupRecord.StorageTransferMode == storage.TransferModeMasterRelay {
+		transferMode = storage.TransferModeMasterRelay
+	}
+	var configRaw []byte
+	if transferMode == storage.TransferModeDirect {
+		configRaw, err = s.cipher.Decrypt(target.ConfigCiphertext)
+		if err != nil {
+			return nil, fmt.Errorf("decrypt storage config: %w", err)
+		}
+	}
 	return &AgentRestoreSpec{
 		RestoreRecordID: restore.ID,
 		BackupRecordID:  backupRecord.ID,
@@ -618,10 +636,11 @@ func (s *RestoreService) GetAgentRestoreSpec(ctx context.Context, node *model.No
 		Compression:     task.Compression,
 		Encrypt:         task.Encrypt,
 		Storage: AgentStorageTargetConfig{
-			ID:     target.ID,
-			Type:   target.Type,
-			Name:   target.Name,
-			Config: json.RawMessage(configRaw),
+			ID:           target.ID,
+			Type:         target.Type,
+			Name:         target.Name,
+			Config:       json.RawMessage(configRaw),
+			TransferMode: transferMode,
 		},
 		StoragePath: backupRecord.StoragePath,
 		FileName:    backupRecord.FileName,
@@ -629,6 +648,63 @@ func (s *RestoreService) GetAgentRestoreSpec(ctx context.Context, node *model.No
 	}, nil
 }

+type AgentArtifactDownload struct {
+	Reader io.ReadCloser
+	Size   int64
+}
+
+// DownloadAgentArtifact opens a Master-local object for authenticated streaming
+// back to the Agent that owns the restore record.
+func (s *RestoreService) DownloadAgentArtifact(ctx context.Context, node *model.Node, restoreID uint) (*AgentArtifactDownload, error) {
+	if node == nil {
+		return nil, apperror.Unauthorized("RESTORE_RECORD_FORBIDDEN", "恢复记录不属于当前节点", nil)
+	}
+	restore, err := s.restores.FindByID(ctx, restoreID)
+	if err != nil {
+		return nil, err
+	}
+	if restore == nil {
+		return nil, apperror.New(404, "RESTORE_RECORD_NOT_FOUND", "恢复记录不存在", nil)
+	}
+	if restore.NodeID != node.ID {
+		return nil, apperror.Unauthorized("RESTORE_RECORD_FORBIDDEN", "恢复记录不属于当前节点", nil)
+	}
+	if isRestoreRecordTerminal(restore.Status) {
+		return nil, apperror.BadRequest("RESTORE_RECORD_TERMINAL", "恢复记录已结束，不能继续下载产物", nil)
+	}
+	record, err := s.records.FindByID(ctx, restore.BackupRecordID)
+	if err != nil {
+		return nil, err
+	}
+	if record == nil {
+		return nil, apperror.New(404, "BACKUP_RECORD_NOT_FOUND", "源备份记录不存在", nil)
+	}
+	target, err := s.targets.FindByID(ctx, record.StorageTargetID)
+	if err != nil {
+		return nil, err
+	}
+	if target == nil || !strings.EqualFold(target.Type, storage.TypeLocalDisk) || record.StorageTransferMode != storage.TransferModeMasterRelay {
+		return nil, apperror.BadRequest("AGENT_ARTIFACT_RELAY_UNSUPPORTED", "该存储目标应由 Agent 直接下载", nil)
+	}
+	configMap := map[string]any{}
+	if err := s.cipher.DecryptJSON(target.ConfigCiphertext, &configMap); err != nil {
+		return nil, fmt.Errorf("decrypt storage config: %w", err)
+	}
+	provider, err := s.storageRegistry.Create(ctx, target.Type, configMap)
+	if err != nil {
+		return nil, fmt.Errorf("create master relay provider: %w", err)
+	}
+	reader, err := provider.Download(ctx, record.StoragePath)
+	if err != nil {
+		return nil, fmt.Errorf("open master relay artifact: %w", err)
+	}
+	size := record.FileSize
+	if size <= 0 {
+		size = -1
+	}
+	return &AgentArtifactDownload{Reader: reader, Size: size}, nil
+}
+
 // UpdateAgentRestore Agent 回传状态/日志。
 func (s *RestoreService) UpdateAgentRestore(ctx context.Context, node *model.Node, restoreID uint, update AgentRestoreUpdate) error {
 	restore, err := s.restores.FindByID(ctx, restoreID)
--- a/server/internal/service/restore_service_test.go
+++ b/server/internal/service/restore_service_test.go
@@ -1,8 +1,10 @@
 package service

 import (
+	"bytes"
 	"context"
 	"encoding/json"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -427,16 +429,27 @@ func TestRestoreServiceAgentRestoreAccessUsesRestoreRecordNode(t *testing.T) {
 	}
 	startedAt := time.Now().UTC()
 	completedAt := startedAt.Add(time.Second)
+	artifact := []byte("central backup artifact")
+	storagePath := "file/2026/05/09/remote.tar.gz"
+	artifactPath := filepath.Join(h.storageDir, filepath.FromSlash(storagePath))
+	if err := os.MkdirAll(filepath.Dir(artifactPath), 0o755); err != nil {
+		t.Fatalf("MkdirAll artifact parent: %v", err)
+	}
+	if err := os.WriteFile(artifactPath, artifact, 0o600); err != nil {
+		t.Fatalf("WriteFile artifact: %v", err)
+	}
 	backupRecord := &model.BackupRecord{
-		TaskID:          task.ID,
-		StorageTargetID: task.StorageTargetID,
-		NodeID:          owner.ID,
-		Status:          model.BackupRecordStatusSuccess,
-		FileName:        "remote.tar.gz",
-		StoragePath:     "file/2026/05/09/remote.tar.gz",
-		Checksum:        "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
-		StartedAt:       startedAt,
-		CompletedAt:     &completedAt,
+		TaskID:              task.ID,
+		StorageTargetID:     task.StorageTargetID,
+		NodeID:              owner.ID,
+		Status:              model.BackupRecordStatusSuccess,
+		FileName:            "remote.tar.gz",
+		StoragePath:         storagePath,
+		FileSize:            int64(len(artifact)),
+		StorageTransferMode: storage.TransferModeMasterRelay,
+		Checksum:            "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
+		StartedAt:           startedAt,
+		CompletedAt:         &completedAt,
 	}
 	if err := h.records.Create(ctx, backupRecord); err != nil {
 		t.Fatalf("Create backup record: %v", err)
@@ -464,6 +477,21 @@ func TestRestoreServiceAgentRestoreAccessUsesRestoreRecordNode(t *testing.T) {
 	if spec.Checksum != backupRecord.Checksum {
 		t.Fatalf("expected spec.Checksum=%q, got %q", backupRecord.Checksum, spec.Checksum)
 	}
+	if spec.Storage.TransferMode != storage.TransferModeMasterRelay {
+		t.Fatalf("expected Master relay restore, got %#v", spec.Storage)
+	}
+	download, err := h.service.DownloadAgentArtifact(ctx, owner, restore.ID)
+	if err != nil {
+		t.Fatalf("DownloadAgentArtifact returned error: %v", err)
+	}
+	downloaded, readErr := io.ReadAll(download.Reader)
+	closeErr := download.Reader.Close()
+	if readErr != nil || closeErr != nil {
+		t.Fatalf("read relayed restore artifact: read=%v close=%v", readErr, closeErr)
+	}
+	if !bytes.Equal(downloaded, artifact) {
+		t.Fatalf("relayed restore artifact differs: %q", downloaded)
+	}
 	if _, err := h.service.GetAgentRestoreSpec(ctx, other, restore.ID); err == nil {
 		t.Fatal("expected non-owner node to be forbidden from restore spec")
 	}
--- a/server/internal/service/verification_service.go
+++ b/server/internal/service/verification_service.go
@@ -299,6 +299,20 @@ func (s *VerificationService) executeLocally(ctx context.Context, verID uint, ta
 		logger.Errorf("创建存储客户端失败：%v", err)
 		return
 	}
+	if backupRecord.BackupKind == model.BackupKindRepository {
+		logger.Infof("验证 CDC 仓库快照及全部引用块：%s", backupRecord.StoragePath)
+		report, verifyErr := backup.NewRepositoryStore(s.cipher.Key()).Verify(ctx, provider, backupRecord.StoragePath, backupRecord.Checksum)
+		if verifyErr != nil {
+			errMessage = verifyErr.Error()
+			summary = "CDC 仓库完整性校验失败"
+			logger.Errorf("验证未通过：%v", verifyErr)
+			return
+		}
+		status = model.VerificationRecordStatusSuccess
+		summary = fmt.Sprintf("CDC 仓库完整性校验通过：%d 个条目、%d 个唯一块、%d bytes", report.Entries, report.Chunks, report.Bytes)
+		logger.Infof("%s", summary)
+		return
+	}
 	fileName := backupRecord.FileName
 	if strings.TrimSpace(fileName) == "" {
 		fileName = filepath.Base(backupRecord.StoragePath)
--- a/server/internal/storage/rclone/provider.go
+++ b/server/internal/storage/rclone/provider.go
@@ -2,6 +2,7 @@ package rclone

 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"sort"
@@ -68,13 +69,56 @@ func (p *Provider) Download(ctx context.Context, objectKey string) (io.ReadClose
 	return reader, nil
 }

+// DownloadRange reads one slice from an object. Most object-storage backends
+// map this to a native HTTP Range request. Backends that reject ranged reads
+// fall back to a full stream while preserving the same interface contract.
+func (p *Provider) DownloadRange(ctx context.Context, objectKey string, offset, length int64) (io.ReadCloser, error) {
+	if offset < 0 || length <= 0 {
+		return nil, fmt.Errorf("rclone download range %s: invalid offset=%d length=%d", objectKey, offset, length)
+	}
+	obj, err := p.rfs.NewObject(ctx, objectKey)
+	if err != nil {
+		return nil, fmt.Errorf("rclone find object %s: %w", objectKey, err)
+	}
+	reader, rangeErr := obj.Open(ctx, &fs.RangeOption{Start: offset, End: offset + length - 1})
+	if rangeErr == nil {
+		return reader, nil
+	}
+	reader, err = obj.Open(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("rclone download range %s (range: %v; fallback: %w)", objectKey, rangeErr, err)
+	}
+	if offset > 0 {
+		if _, err := io.CopyN(io.Discard, reader, offset); err != nil {
+			closeErr := reader.Close()
+			return nil, errors.Join(fmt.Errorf("rclone seek object %s: %w", objectKey, err), closeErr)
+		}
+	}
+	return &limitedReadCloser{Reader: io.LimitReader(reader, length), closer: reader}, nil
+}
+
+type limitedReadCloser struct {
+	io.Reader
+	closer io.Closer
+}
+
+func (r *limitedReadCloser) Close() error {
+	return r.closer.Close()
+}
+
 // Delete 通过 rclone 删除远端对象。
 func (p *Provider) Delete(ctx context.Context, objectKey string) error {
 	obj, err := p.rfs.NewObject(ctx, objectKey)
 	if err != nil {
+		if errors.Is(err, fs.ErrorObjectNotFound) || errors.Is(err, fs.ErrorDirNotFound) {
+			return nil
+		}
 		return fmt.Errorf("rclone find object %s: %w", objectKey, err)
 	}
 	if err := obj.Remove(ctx); err != nil {
+		if errors.Is(err, fs.ErrorObjectNotFound) || errors.Is(err, fs.ErrorDirNotFound) {
+			return nil
+		}
 		return fmt.Errorf("rclone delete %s: %w", objectKey, err)
 	}
 	return nil
@@ -102,6 +146,9 @@ func (p *Provider) List(ctx context.Context, prefix string) ([]storage.ObjectInf
 		return nil
 	})
 	if err != nil {
+		if errors.Is(err, fs.ErrorDirNotFound) || errors.Is(err, fs.ErrorObjectNotFound) {
+			return []storage.ObjectInfo{}, nil
+		}
 		return nil, fmt.Errorf("rclone list %s: %w", prefix, err)
 	}
 	return items, nil
--- a/server/internal/storage/types.go
+++ b/server/internal/storage/types.go
@@ -34,6 +34,14 @@ const (
 	TypeFTP         = string(ProviderTypeFTP)
 )

+const (
+	// TransferModeDirect lets an Agent write to a network-accessible backend.
+	TransferModeDirect = "direct"
+	// TransferModeMasterRelay streams an artifact through the authenticated
+	// Agent API so a remote source can use storage mounted only on the Master.
+	TransferModeMasterRelay = "master_relay"
+)
+
 type ObjectInfo struct {
 	Key       string    `json:"key"`
 	Size      int64     `json:"size"`
@@ -49,6 +57,13 @@ type StorageProvider interface {
 	List(ctx context.Context, prefix string) ([]ObjectInfo, error)
 }

+// StorageRangeDownloader is an optional capability used by packed repository
+// backups. Implementations return exactly the requested byte range when the
+// backend supports ranged reads and may transparently fall back to a full read.
+type StorageRangeDownloader interface {
+	DownloadRange(ctx context.Context, objectKey string, offset, length int64) (io.ReadCloser, error)
+}
+
 type ProviderFactory interface {
 	Type() ProviderType
 }
@@ -92,7 +107,8 @@ func ParseProviderType(value string) ProviderType {
 }

 type LocalDiskConfig struct {
-	BasePath string `json:"basePath"`
+	BasePath    string `json:"basePath"`
+	MasterRelay bool   `json:"masterRelay"`
 }

 type S3Config struct {
@@ -151,4 +167,3 @@ type FTPConfig struct {
 type StorageDirCleaner interface {
 	RemoveEmptyDirs(ctx context.Context, prefix string) error
 }
-