fix(plugins): trust official signing keys for offline installation

apps/desktop/src/components/plugins/PluginContributionsPanel.vue

@@ -24,6 +24,7 @@ import { useQueryStore } from "@/stores/queryStore";
 import type { InstalledPlugin, PluginInstallResult, PluginRepository, PluginRepositoryCatalogResult, PluginTrustedKey } from "@/types/database";
 import { useI18n } from "vue-i18n";
 import { safeLocalStorageGet, safeLocalStorageSet } from "@/lib/backend/safeStorage";
+import { translateBackendError } from "@/i18n/backend-errors";
 
 const props = defineProps<{
   focusTarget?: PluginCenterFocus | null;
@@ -389,7 +390,7 @@ async function installPlugin(source: string | File) {
     const result = await api.installPluginPackage(source, allowUnsigned.value);
     await finishInstall(result);
   } catch (cause) {
-    toast(cause instanceof Error ? cause.message : String(cause), 8000);
+    toast(translateBackendError(t, cause), 8000);
   } finally {
     installing.value = false;
   }
@@ -422,7 +423,7 @@ async function installPluginFromUrl() {
     installUrl.value = "";
     await finishInstall(result);
   } catch (cause) {
-    toast(cause instanceof Error ? cause.message : String(cause), 8000);
+    toast(translateBackendError(t, cause), 8000);
   } finally {
     unlisten?.();
     urlInstalling.value = false;

apps/desktop/src/i18n/__tests__/backendErrors.spec.ts

@@ -454,6 +454,26 @@ describe("backend error translation", () => {
     expect(translateBackendError(t, error, "ClickHouse error: table analytics.events does not exist")).toBe(`${t("backendErrors.legacy")}\n\nClickHouse error: table analytics.events does not exist`);
   });
 
+  test("renders plugin signature failures without exposing the JSON error envelope", () => {
+    const detail = "Plugin package is signed by untrusted key 'dbx-store-release-2026'";
+    const error = JSON.stringify({
+      version: 1,
+      code: "DBX-LEGACY-0001",
+      messageKey: "backendErrors.legacy",
+      messageParams: {},
+      source: "legacyBackend",
+      origin: { subsystem: "backend", adapter: "legacy" },
+      operationOutcome: "unknown",
+      detail,
+    });
+
+    for (const locale of ["zh-CN", "en"] as const) {
+      const t = translatorFor(locale);
+      expect(translateBackendError(t, error)).toBe(`${t("backendErrors.legacy")}\n\n${detail}`);
+      expect(translateBackendError(t, new Error(error))).toBe(`${t("backendErrors.legacy")}\n\n${detail}`);
+    }
+  });
+
   test("does not append the generic transport fallback to a structured error", () => {
     const t = translatorFor("zh-CN");
     const error = {

apps/desktop/src/lib/__tests__/plugins/pluginCenterIntegration.spec.ts

@@ -26,6 +26,16 @@ describe("plugin center integration", () => {
     expect(driverStoreSource).not.toContain("PluginContributionsPanel");
   });
 
+  it("formats structured backend errors for local and URL package installs", () => {
+    const localInstall = pluginCenterSource.slice(pluginCenterSource.indexOf("async function installPlugin("), pluginCenterSource.indexOf("function isHttpPackageUrl("));
+    const urlInstall = pluginCenterSource.slice(pluginCenterSource.indexOf("async function installPluginFromUrl("), pluginCenterSource.indexOf("const urlProgressPercent"));
+
+    for (const installSource of [localInstall, urlInstall]) {
+      expect(installSource).toContain("toast(translateBackendError(t, cause), 8000)");
+      expect(installSource).not.toContain("String(cause)");
+    }
+  });
+
   it("creates and edits plugin connections in the unified connection dialog", () => {
     expect(appDialogsSource).toContain(':edit-config="editConfig"');
     expect(appDialogsSource).toContain(':plugin-provider="connectionPluginProvider"');