Fix shiki and diff caching

src/lib/tool-render-cache.ts

@@ -0,0 +1,22 @@
+import type { RenderCache } from "../types/message"
+
+const toolRenderCache = new Map<string, RenderCache>()
+
+export function getToolRenderCache(key?: string | null): RenderCache | undefined {
+  if (!key) return undefined
+  return toolRenderCache.get(key)
+}
+
+export function setToolRenderCache(key: string | undefined | null, cache?: RenderCache): void {
+  if (!key) return
+  if (cache) {
+    toolRenderCache.set(key, cache)
+  } else {
+    toolRenderCache.delete(key)
+  }
+}
+
+export function clearToolRenderCache(key?: string | null): void {
+  if (!key) return
+  toolRenderCache.delete(key)
+}