diff --git a/weed/server/filer_server_format.go b/weed/server/filer_server_format.go
index 830570cfa..8a156390d 100644
--- a/weed/server/filer_server_format.go
+++ b/weed/server/filer_server_format.go
@@ -58,6 +58,19 @@ func formatChunkIdentity(chunks []*filer_pb.FileChunk) []byte {
 	return digest.Sum(nil)
 }
 
+// repackSourceIdentity digests every entry field that influenced a repack's
+// output: the chunk list it read, the size the layout was validated against,
+// the TTL and expiry anchors its new chunks were assigned with, and the
+// hard-link and remote state its guards evaluated.
+func repackSourceIdentity(entry *filer.Entry) []byte {
+	digest := md5.New()
+	digest.Write(formatChunkIdentity(entry.GetChunks()))
+	fmt.Fprintf(digest, "%d:%d:%d:%d:%t:%x:%t",
+		entry.FileSize, entry.TtlSec, entry.Crtime.UnixNano(), entry.Mtime.UnixNano(),
+		entry.IsExpireS3Enabled(), []byte(entry.HardLinkId), entry.Remote != nil)
+	return digest.Sum(nil)
+}
+
 // roundUpToVolumeTTL returns the smallest volume-TTL-representable seconds
 // value not below the argument. A volume TTL is at most 255 of one unit and
 // SecondsToTTL truncates anything else downward, which would let chunks
@@ -307,7 +320,7 @@ func (fs *FilerServer) formatRepack(ctx context.Context, w http.ResponseWriter,
 		return
 	}
 	oldChunks := entry.GetChunks()
-	oldIdentity := formatChunkIdentity(oldChunks)
+	sourceIdentity := repackSourceIdentity(entry)
 	if len(oldChunks) == 0 {
 		writeJsonError(w, r, http.StatusBadRequest, errors.New("entry has no chunks to repack"))
 		return
@@ -408,9 +421,12 @@ func (fs *FilerServer) formatRepack(ctx context.Context, w http.ResponseWriter,
 	}
 
 	// The entry lock is filer-local, so a writer on another filer is not
-	// blocked by it. Re-read from the store and revalidate right before the
-	// swap: the unguarded window shrinks from the whole repack to this
-	// commit. Full enforcement needs owner routing.
+	// blocked by it. Re-read from the store and conflict on any change to
+	// state that influenced this repack - chunks, size, TTL and expiry
+	// anchors, hard-link and remote state - so the swap can never pair fresh
+	// metadata with chunks built from stale inputs. The unguarded window
+	// shrinks from the whole repack to this commit; within it repack races
+	// like any ordinary writer. Closing it needs owner routing.
 	current, err := fs.filer.FindEntry(ctx, fullPath)
 	if err != nil {
 		cleanup()
@@ -421,7 +437,7 @@ func (fs *FilerServer) formatRepack(ctx context.Context, w http.ResponseWriter,
 		}
 		return
 	}
-	if !bytes.Equal(formatChunkIdentity(current.GetChunks()), oldIdentity) {
+	if !bytes.Equal(repackSourceIdentity(current), sourceIdentity) {
 		cleanup()
 		writeJsonError(w, r, http.StatusConflict, errors.New("entry changed during repack"))
 		return
diff --git a/weed/server/filer_server_format_test.go b/weed/server/filer_server_format_test.go
index f95d0e596..77cae537b 100644
--- a/weed/server/filer_server_format_test.go
+++ b/weed/server/filer_server_format_test.go
@@ -2,8 +2,10 @@ package weed_server
 
 import (
 	"bytes"
+	"github.com/seaweedfs/seaweedfs/weed/filer"
 	"math"
 	"testing"
+	"time"
 
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
@@ -22,7 +24,7 @@ func TestRoundUpToVolumeTTL(t *testing.T) {
 		{3600, 3600},
 		{3601, 3660},
 		{255 * 60, 255 * 60},
-		{255*60 + 1, 5 * 3600},           // minutes overflow 255, ceil to hours
+		{255*60 + 1, 5 * 3600},        // minutes overflow 255, ceil to hours
 		{20_000_000, 232 * 24 * 3600}, // ~231.5 days, ceil to days
 		{int64(math.MaxInt32), 0},     // beyond every unit's 255 cap: no TTL, never a shortened one
 	}
@@ -45,6 +47,39 @@ func TestRoundUpToVolumeTTL(t *testing.T) {
 	}
 }
 
+func TestRepackSourceIdentity(t *testing.T) {
+	base := func() *filer.Entry {
+		return &filer.Entry{
+			FullPath: "/videos/movie.ts",
+			Attr: filer.Attr{
+				FileSize: 30, TtlSec: 600,
+				Crtime: time.Unix(1000, 0), Mtime: time.Unix(2000, 0),
+			},
+			Chunks: []*filer_pb.FileChunk{{FileId: "1,ab", Offset: 0, Size: 30}},
+		}
+	}
+	identity := repackSourceIdentity(base())
+	if !bytes.Equal(identity, repackSourceIdentity(base())) {
+		t.Fatalf("identity is not deterministic")
+	}
+	mutations := map[string]func(*filer.Entry){
+		"ttl cleared":  func(e *filer.Entry) { e.TtlSec = 0 },
+		"size changed": func(e *filer.Entry) { e.FileSize = 31 },
+		"mtime moved":  func(e *filer.Entry) { e.Mtime = time.Unix(3000, 0) },
+		"crtime moved": func(e *filer.Entry) { e.Crtime = time.Unix(1001, 0) },
+		"hard linked":  func(e *filer.Entry) { e.HardLinkId = []byte{1} },
+		"went remote":  func(e *filer.Entry) { e.Remote = &filer_pb.RemoteEntry{} },
+		"chunk moved":  func(e *filer.Entry) { e.Chunks[0].Offset = 1 },
+	}
+	for name, mutate := range mutations {
+		changed := base()
+		mutate(changed)
+		if bytes.Equal(identity, repackSourceIdentity(changed)) {
+			t.Fatalf("identity ignored: %s", name)
+		}
+	}
+}
+
 func TestFormatChunkIdentity(t *testing.T) {
 	chunks := []*filer_pb.FileChunk{
 		{FileId: "1,ab", Offset: 0, Size: 10},