fix(local): preserve completed files on canceled uploads

- Keep completed same-path files during canceled upload cleanup.\n- Add regression coverage for completed replacements.

Co-authored-by: LunelleEverdawn <lunelle+suyunmeng@oplist.org>

drivers/local/driver.go

@@ -420,7 +420,9 @@ func (d *Local) Put(ctx context.Context, dstDir model.Obj, stream model.FileStre
 	defer func() {
 		_ = out.Close()
 		if errors.Is(err, context.Canceled) {
-			_ = os.Remove(fullPath)
+			if info, statErr := os.Stat(fullPath); statErr == nil && info.Size() != stream.GetSize() {
+				_ = os.Remove(fullPath)
+			}
 		}
 	}()
 	err = utils.CopyWithCtx(ctx, out, stream, stream.GetSize(), up)

drivers/local/put_test.go

@@ -0,0 +1,59 @@
+package local
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/OpenListTeam/OpenList/v4/internal/model"
+	"github.com/OpenListTeam/OpenList/v4/internal/stream"
+)
+
+type blockedReader struct {
+	started chan struct{}
+	release chan struct{}
+}
+
+func (r blockedReader) Read([]byte) (int, error) {
+	close(r.started)
+	<-r.release
+	return 0, context.Canceled
+}
+
+func TestPutCancellationPreservesCompletedReplacement(t *testing.T) {
+	root := t.TempDir()
+	const content = "completed replacement"
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	reader := blockedReader{started: make(chan struct{}), release: make(chan struct{})}
+	file := &stream.FileStream{
+		Obj:    &model.Object{Name: "test.bin", Size: int64(len(content))},
+		Reader: reader,
+	}
+
+	putDone := make(chan error, 1)
+	go func() {
+		putDone <- (&Local{}).Put(ctx, &model.Object{Path: root}, file, nil)
+	}()
+	<-reader.started
+
+	path := filepath.Join(root, "test.bin")
+	if err := os.WriteFile(path, []byte(content), 0o666); err != nil {
+		t.Fatal(err)
+	}
+	cancel()
+	close(reader.release)
+	if err := <-putDone; !errors.Is(err, context.Canceled) {
+		t.Fatalf("Put error = %v, want context.Canceled", err)
+	}
+
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("completed replacement was removed: %v", err)
+	}
+	if string(got) != content {
+		t.Fatalf("replacement contents = %q, want %q", got, content)
+	}
+}