fix(webui): anchor sent prompts during active turns

webui/src/tests/markdown-text-lazy-failure.test.tsx

@@ -0,0 +1,25 @@
+import { render, screen, waitFor } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+
+describe("MarkdownText lazy renderer failure", () => {
+  it("keeps rendering plain text if the markdown renderer chunk fails to load", async () => {
+    vi.resetModules();
+    vi.doMock("@/components/MarkdownTextRenderer", () => {
+      throw new Error("markdown renderer failed to load");
+    });
+    const consoleError = vi.spyOn(console, "error").mockImplementation(() => {});
+
+    try {
+      const { MarkdownText } = await import("@/components/MarkdownText");
+
+      render(<MarkdownText>hello **markdown**</MarkdownText>);
+
+      await waitFor(() => {
+        expect(screen.getByText("hello **markdown**")).toBeInTheDocument();
+      });
+    } finally {
+      consoleError.mockRestore();
+      vi.doUnmock("@/components/MarkdownTextRenderer");
+    }
+  });
+});