test: restore the dashboard plugin SDK dialog/toast surface guard dropped by #120071

exposePluginSDK() is the runtime API third-party dashboard plugins consume
from window.__HERMES_PLUGIN_SDK__; nothing else exercises it. Restored
web/src/plugins/registry.test.ts (#50547): Dialog family, ConfirmDialog and
Toast on components; useToast/useConfirmDelete (and the React hooks) on hooks.

web/src/plugins/registry.test.ts

@@ -0,0 +1,46 @@
+/**
+ * Smoke test for the plugin SDK surface additions.
+ *
+ * Verifies that `exposePluginSDK()` writes the new dialog/toast primitives to
+ * `window.__HERMES_PLUGIN_SDK__`. Each new key is checked individually so a
+ * regression in one helper doesn't mask the others.
+ *
+ * Companion to the additive PR "feat(plugins): expose Dialog/ConfirmDialog/
+ * Toast/useToast/useConfirmDelete on the plugin SDK". See issue #50547.
+ */
+import { beforeEach, describe, expect, it } from "vitest";
+import { exposePluginSDK } from "./registry";
+
+describe("plugin SDK dialog/toast surface", () => {
+  beforeEach(() => {
+    // Reset window between tests so exposePluginSDK() writes fresh.
+    (globalThis as unknown as { window: Record<string, unknown> }).window = {
+      __HERMES_PLUGINS__: undefined,
+      __HERMES_PLUGIN_SDK__: undefined,
+    };
+  });
+
+  it("exposes Dialog + subcomponents on components", () => {
+    exposePluginSDK();
+    const sdk = (globalThis as unknown as { window: { __HERMES_PLUGIN_SDK__: { components: Record<string, unknown>; hooks: Record<string, unknown> } } }).window.__HERMES_PLUGIN_SDK__;
+    expect(sdk.components.Dialog).toBeDefined();
+    expect(sdk.components.DialogContent).toBeDefined();
+    expect(sdk.components.DialogHeader).toBeDefined();
+    expect(sdk.components.DialogTitle).toBeDefined();
+    expect(sdk.components.DialogDescription).toBeDefined();
+    expect(sdk.components.DialogFooter).toBeDefined();
+    expect(sdk.components.DialogClose).toBeDefined();
+    expect(sdk.components.ConfirmDialog).toBeDefined();
+    expect(sdk.components.Toast).toBeDefined();
+  });
+
+  it("exposes useToast and useConfirmDelete on hooks", () => {
+    exposePluginSDK();
+    const sdk = (globalThis as unknown as { window: { __HERMES_PLUGIN_SDK__: { components: Record<string, unknown>; hooks: Record<string, unknown> } } }).window.__HERMES_PLUGIN_SDK__;
+    expect(typeof sdk.hooks.useToast).toBe("function");
+    expect(typeof sdk.hooks.useConfirmDelete).toBe("function");
+    // Original React hooks still present (no accidental removal).
+    expect(typeof sdk.hooks.useState).toBe("function");
+    expect(typeof sdk.hooks.useCallback).toBe("function");
+  });
+});