diff --git a/chfs-ng/internal/api/server.go b/chfs-ng/internal/api/server.go
index 502c665..7074340 100644
--- a/chfs-ng/internal/api/server.go
+++ b/chfs-ng/internal/api/server.go
@@ -76,7 +76,17 @@ func (s *Server) Handler() http.Handler {
 	mux.HandleFunc("/chfs/shared/", s.shared)
 	mux.HandleFunc("/chfs/preview", s.preview)
 	mux.HandleFunc("/", s.fileHandler)
-	return s.ipFilter(mux)
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Go's ServeMux canonicalizes a subtree route before dispatching.
+		// CHFS v4 deliberately returns a relative 301 from /chfs/shared, so
+		// intercept the exact path before ServeMux gets a chance to rewrite it.
+		if r.URL.Path == "/chfs/shared" {
+			s.shared(w, r)
+			return
+		}
+		mux.ServeHTTP(w, r)
+	})
+	return s.ipFilter(h)
 }
 func account(r *http.Request, s *Server) *auth.Account {
 	c, err := r.Cookie("JWT")
@@ -659,7 +669,9 @@ func (s *Server) shared(w http.ResponseWriter, r *http.Request) {
 		if r.URL.RawQuery != "" {
 			location += "?" + r.URL.RawQuery
 		}
-		http.Redirect(w, r, location, http.StatusMovedPermanently)
+		w.Header().Set("Content-Disposition", `attachment;filename="shared"`)
+		w.Header().Set("Location", location)
+		w.WriteHeader(http.StatusMovedPermanently)
 		return
 	}
 	p := strings.Trim(strings.TrimPrefix(r.URL.Path, "/chfs/shared/"), "/")
@@ -808,6 +820,7 @@ func (s *Server) downloadDir(w http.ResponseWriter, r *http.Request) {
 		name = "download"
 	}
 	w.Header().Set("Content-Type", "application/zip")
+	// CHFS v4 does not emit Content-Disposition for directory archives.
 	zw := zip.NewWriter(w)
 	defer zw.Close()
 	var walk func(string, string) error
diff --git a/chfs-ng/internal/api/share_archive_test.go b/chfs-ng/internal/api/share_archive_test.go
new file mode 100644
index 0000000..2628278
--- /dev/null
+++ b/chfs-ng/internal/api/share_archive_test.go
@@ -0,0 +1,95 @@
+package api
+
+import (
+	"archive/zip"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"chfs-ng/internal/auth"
+	"chfs-ng/internal/storage"
+)
+
+func TestSharedRoutesMatchCHFS(t *testing.T) {
+	root := t.TempDir()
+	if err := os.WriteFile(filepath.Join(root, "hello.txt"), []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	s := &Server{Store: storage.Local{Root: root}, Auth: &auth.Manager{Accounts: map[string]*auth.Account{}, Guest: &auth.Account{Mask: auth.Read | auth.Write | auth.Delete}}}
+
+	r := httptest.NewRequest(http.MethodGet, "/chfs/shared?file=hello.txt", nil)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, r)
+	if w.Code != http.StatusMovedPermanently || w.Header().Get("Location") != "shared/?file=hello.txt" {
+		t.Fatalf("shared redirect: status=%d location=%q", w.Code, w.Header().Get("Location"))
+	}
+
+	r = httptest.NewRequest(http.MethodGet, "/chfs/shared/hello.txt", nil)
+	w = httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, r)
+	if w.Code != http.StatusOK || w.Header().Get("Content-Disposition") != `attachment;filename="hello.txt"` {
+		t.Fatalf("shared file: status=%d disposition=%q", w.Code, w.Header().Get("Content-Disposition"))
+	}
+	body, _ := io.ReadAll(w.Result().Body)
+	if string(body) != "hello" {
+		t.Fatalf("shared body=%q", body)
+	}
+}
+
+func TestDownloadDirArchiveHeadersAndEntries(t *testing.T) {
+	root := t.TempDir()
+	dir := filepath.Join(root, "pack")
+	if err := os.Mkdir(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "a.txt"), []byte("abc"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	s := &Server{Store: storage.Local{Root: root}, Auth: &auth.Manager{Accounts: map[string]*auth.Account{}, Guest: &auth.Account{Mask: auth.Read | auth.Write | auth.Delete}}}
+
+	r := httptest.NewRequest(http.MethodGet, "/chfs/downloaddir/pack", nil)
+	w := httptest.NewRecorder()
+	s.Handler().ServeHTTP(w, r)
+	if w.Code != http.StatusOK {
+		t.Fatalf("archive status=%d body=%s", w.Code, w.Body.String())
+	}
+	if got := w.Header().Get("Content-Type"); got != "application/zip" {
+		t.Fatalf("archive content type=%q", got)
+	}
+	if got := w.Header().Get("Content-Disposition"); got != "" {
+		t.Fatalf("CHFS archive must not emit Content-Disposition, got %q", got)
+	}
+	zr, err := zip.NewReader(bytesReaderAt{r: w.Body.Bytes()}, int64(w.Body.Len()))
+	if err != nil {
+		t.Fatalf("open archive: %v", err)
+	}
+	if len(zr.File) != 1 || zr.File[0].Name != "a.txt" {
+		t.Fatalf("archive entries=%v", archiveNames(zr.File))
+	}
+	if zr.File[0].UncompressedSize64 != 3 {
+		t.Fatalf("archive size=%d", zr.File[0].UncompressedSize64)
+	}
+}
+
+type bytesReaderAt struct{ r []byte }
+
+func (b bytesReaderAt) ReadAt(p []byte, off int64) (int, error) {
+	if off >= int64(len(b.r)) {
+		return 0, io.EOF
+	}
+	n := copy(p, b.r[off:])
+	if n < len(p) {
+		return n, io.EOF
+	}
+	return n, nil
+}
+func archiveNames(files []*zip.File) []string {
+	n := make([]string, 0, len(files))
+	for _, f := range files {
+		n = append(n, f.Name)
+	}
+	return n
+}