perf(components): use Streamdown static mode for finished markdown

packages/components/src/components/ai-gui/markdown-renderer.tsx

@@ -58,6 +58,7 @@ import { useResolvedTheme } from '../../theme-provider';
 import type { ConversationFontSize } from '@/atoms/settings';
 import { useTaskImageUrl } from '@/hooks/use-task-image';
 import { MarkdownDiffBlock } from './markdown-diff-block';
+import { resolveMarkdownStreamdownMode } from './markdown-streamdown-mode';
 import { createMarkdownMermaidConfig, createMarkdownMermaidPlugin } from './markdown-mermaid';
 import { MermaidDiagramViewer, type MermaidDiagramSelection } from './mermaid-diagram-viewer';
 
@@ -1409,7 +1410,7 @@ export const MarkdownRenderer = memo(function MarkdownRenderer({
           // remount when raw-HTML mode or Mermaid theme changes so sanitized
           // rendering and diagram colors update correctly.
           key={streamdownKey}
-          mode="streaming"
+          mode={resolveMarkdownStreamdownMode(isStreaming)}
           className="space-y-0"
           controls={STREAMDOWN_CONTROLS}
           isAnimating={isStreaming}

packages/components/src/components/ai-gui/markdown-streamdown-mode.ts

@@ -0,0 +1,3 @@
+export function resolveMarkdownStreamdownMode(isStreaming: boolean): 'static' | 'streaming' {
+  return isStreaming ? 'streaming' : 'static';
+}

packages/components/tests/markdown-streamdown-mode.test.ts

@@ -0,0 +1,13 @@
+import { describe, expect, it } from 'vitest';
+
+import { resolveMarkdownStreamdownMode } from '../src/components/ai-gui/markdown-streamdown-mode';
+
+describe('resolveMarkdownStreamdownMode', () => {
+  it('uses static mode for finished markdown', () => {
+    expect(resolveMarkdownStreamdownMode(false)).toBe('static');
+  });
+
+  it('uses streaming mode while a turn is still growing', () => {
+    expect(resolveMarkdownStreamdownMode(true)).toBe('streaming');
+  });
+});