fix: omit status on non-archive writes, skip finished in refresh and scan

backend/main_test.go

@@ -160,3 +160,39 @@ func TestPutStatusValidation(t *testing.T) {
 		})
 	}
 }
+
+// A PUT that omits the status field entirely (what a userscript build
+// predating the column sends) is the actual preserve path — the "" case
+// above only exercises the fresh-INSERT default and never touches an
+// existing bucket. This must both keep the archived bucket and still apply
+// the chapter progress carried in the same request.
+func TestPutOmittedStatusPreservesArchivedAndAppliesProgress(t *testing.T) {
+	srv := newTestServer(t)
+
+	seed := httptest.NewRequest(http.MethodPut, "/bookmarks/asura:solo",
+		strings.NewReader(`{"title":"Solo","status":"archived"}`))
+	rr := httptest.NewRecorder()
+	srv.ServeHTTP(rr, auth(seed))
+	if rr.Code != http.StatusOK {
+		t.Fatalf("seed status = %d, want 200 (body %s)", rr.Code, rr.Body.String())
+	}
+
+	req := httptest.NewRequest(http.MethodPut, "/bookmarks/asura:solo",
+		strings.NewReader(`{"title":"Solo","last_chapter":"12","last_chapter_num":12}`))
+	rr = httptest.NewRecorder()
+	srv.ServeHTTP(rr, auth(req))
+	if rr.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200 (body %s)", rr.Code, rr.Body.String())
+	}
+
+	var got Bookmark
+	if err := json.Unmarshal(rr.Body.Bytes(), &got); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if got.Status != "archived" {
+		t.Fatalf("stored status = %q, want %q", got.Status, "archived")
+	}
+	if got.LastChapterNum != 12 {
+		t.Fatalf("stored last_chapter_num = %v, want 12", got.LastChapterNum)
+	}
+}