diff --git a/internal/stage/archive.go b/internal/stage/archive.go
index ffbedcb..67814e0 100644
--- a/internal/stage/archive.go
+++ b/internal/stage/archive.go
@@ -18,6 +18,10 @@ import (
 )
 
 type archiveStage struct{}
+type archiveUploadFile struct {
+	RelativePath string
+	LocalPath    string
+}
 
 var archivePrerequisiteStages = []string{
 	"prepare",
@@ -112,7 +116,12 @@ func (archiveStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*S
 		return nil, fmt.Errorf("archive: run id is required")
 	}
 
-	runFiles, err := collectArchiveRunFiles(workDir)
+	manifestSource, err := resolveArchiveManifestSource(env, m, workDir)
+	if err != nil {
+		return nil, fmt.Errorf("archive: resolve manifest source: %w", err)
+	}
+
+	runFiles, err := collectArchiveRunFiles(workDir, manifestSource)
 	if err != nil {
 		return nil, fmt.Errorf("archive: collect run files: %w", err)
 	}
@@ -120,21 +129,13 @@ func (archiveStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*S
 	if err != nil {
 		return nil, fmt.Errorf("archive: resolve promotion rules: %w", err)
 	}
-	currentManifestSource := filepath.Join(workDir, "manifest.json")
-	if info, err := os.Stat(currentManifestSource); err != nil {
-		return nil, fmt.Errorf("archive: current manifest source %q: %w", currentManifestSource, err)
-	} else if info.IsDir() {
-		return nil, fmt.Errorf("archive: current manifest source %q is a directory", currentManifestSource)
-	}
-
 	runUploaded := make([]string, 0, len(runFiles))
-	for _, rel := range runFiles {
-		localPath := filepath.Join(workDir, filepath.FromSlash(rel))
-		key := artifacts.S3RunRelativeDestinationKey(runPrefix, rel)
-		if _, err := env.ObjectStore.Upload(ctx, localPath, key, storage.UploadOptions{}); err != nil {
-			return nil, fmt.Errorf("archive: upload run file %q to %q: %w", rel, key, err)
+	for _, file := range runFiles {
+		key := artifacts.S3RunRelativeDestinationKey(runPrefix, file.RelativePath)
+		if _, err := env.ObjectStore.Upload(ctx, file.LocalPath, key, storage.UploadOptions{}); err != nil {
+			return nil, fmt.Errorf("archive: upload run file %q to %q: %w", file.RelativePath, key, err)
 		}
-		runUploaded = append(runUploaded, rel)
+		runUploaded = append(runUploaded, file.RelativePath)
 	}
 
 	promotedUploaded := make([]string, 0, len(promotions))
@@ -375,8 +376,8 @@ func resolveWorkDirRelativePath(workDir, rel string) (string, error) {
 	return cleanedFull, nil
 }
 
-func collectArchiveRunFiles(workDir string) ([]string, error) {
-	files := make([]string, 0, 64)
+func collectArchiveRunFiles(workDir, manifestPath string) ([]archiveUploadFile, error) {
+	files := make([]archiveUploadFile, 0, 64)
 
 	for _, dirName := range archiveRunUploadDirs {
 		fullDir := filepath.Join(workDir, dirName)
@@ -403,30 +404,72 @@ func collectArchiveRunFiles(workDir string) ([]string, error) {
 				return fmt.Errorf("relative path from %q to %q: %w", workDir, path, err)
 			}
 			rel = filepath.ToSlash(rel)
-			files = append(files, rel)
+			files = append(files, archiveUploadFile{
+				RelativePath: rel,
+				LocalPath:    path,
+			})
 			return nil
 		}); err != nil {
 			return nil, fmt.Errorf("walk %q: %w", fullDir, err)
 		}
 	}
 
-	manifestPath := filepath.Join(workDir, "manifest.json")
 	manifestInfo, err := os.Stat(manifestPath)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return nil, fmt.Errorf("manifest.json not found in workdir %q", workDir)
+			return nil, fmt.Errorf("manifest.json not found (checked path %q)", manifestPath)
 		}
 		return nil, fmt.Errorf("stat %q: %w", manifestPath, err)
 	}
 	if manifestInfo.IsDir() {
 		return nil, fmt.Errorf("manifest path %q is a directory", manifestPath)
 	}
-	files = append(files, "manifest.json")
+	files = append(files, archiveUploadFile{
+		RelativePath: "manifest.json",
+		LocalPath:    manifestPath,
+	})
 
-	sort.Strings(files)
+	sort.Slice(files, func(i, j int) bool {
+		return files[i].RelativePath < files[j].RelativePath
+	})
 	return files, nil
 }
 
+func resolveArchiveManifestSource(env *Env, m *manifest.Manifest, workDir string) (string, error) {
+	candidates := make([]string, 0, 3)
+	candidates = append(candidates, filepath.Join(workDir, "manifest.json"))
+
+	sessionID := strings.TrimSpace(env.Config.Session.SessionID)
+	if sessionID == "" && m != nil {
+		sessionID = strings.TrimSpace(m.SessionID)
+	}
+	if sessionID != "" {
+		sessionManifest := filepath.Join(artifacts.SessionWorkDir(env.Config.Pipeline.Workspace.Root, sessionID), "manifest.json")
+		candidates = append(candidates, sessionManifest)
+	}
+
+	seen := make(map[string]struct{}, len(candidates))
+	for _, candidate := range candidates {
+		clean := filepath.Clean(candidate)
+		if _, ok := seen[clean]; ok {
+			continue
+		}
+		seen[clean] = struct{}{}
+		info, err := os.Stat(clean)
+		if err != nil {
+			if os.IsNotExist(err) {
+				continue
+			}
+			return "", fmt.Errorf("stat %q: %w", clean, err)
+		}
+		if info.IsDir() {
+			continue
+		}
+		return clean, nil
+	}
+	return "", fmt.Errorf("manifest.json not found in run workdir or session workdir")
+}
+
 func writeCurrentManifestSnapshot(m *manifest.Manifest, archiveMetadata map[string]any) (string, error) {
 	if m == nil {
 		return "", fmt.Errorf("manifest is required")