fix(assistant): mysql message storage, migration metadata and per-page bundle cost (#6530)

apps/nextjs/src/components/assistant/assistant-gate.tsx

@@ -0,0 +1,79 @@
+"use client";
+
+import type { PropsWithChildren } from "react";
+import { useMemo } from "react";
+import dynamic from "next/dynamic";
+
+import { useScopedI18n } from "@homarr/translation/client";
+import { AssistantWidgetRendererProvider } from "@homarr/widgets";
+
+import { AssistantContext } from "./assistant-context";
+import { AssistantBoardWidgetLazy } from "./assistant-widget-lazy";
+import { useRegisterAssistantSpotlightPlaceholder } from "./assistant-spotlight-placeholder";
+
+/**
+ * The enabled runtime is the expensive half of the assistant (assistant-ui, Lexical, Markdown,
+ * Mermaid). Loading it through `next/dynamic` puts it in its own chunk that is only requested when
+ * this component actually renders. Because `enabled` is resolved on the server and handed down as a
+ * prop, an instance with the assistant switched off never renders it, so the chunk is never part of
+ * the page payload. SSR stays on so enabled instances render children in the initial HTML without a
+ * loading flash or a remount once the chunk arrives.
+ */
+const EnabledAssistantRoot = dynamic(() =>
+  import("./assistant-provider").then((module) => ({ default: module.EnabledAssistantRoot })),
+);
+
+const DisabledAssistant = ({ children, description }: PropsWithChildren<{ description: string }>) => {
+  useRegisterAssistantSpotlightPlaceholder(description);
+
+  const value = useMemo(
+    () => ({
+      enabled: false,
+      unavailableDescription: description,
+      opened: false,
+      isRunning: false,
+      isRefreshing: false,
+      unreadCount: 0,
+      open: () => undefined,
+      close: () => undefined,
+      toggle: () => undefined,
+      sendPrompt: () => false,
+      refreshCurrentView: () => Promise.resolve(),
+    }),
+    [description],
+  );
+
+  return (
+    <AssistantContext.Provider value={value}>
+      <AssistantWidgetRendererProvider renderer={AssistantBoardWidgetLazy}>{children}</AssistantWidgetRendererProvider>
+    </AssistantContext.Provider>
+  );
+};
+
+/**
+ * Why the assistant is or is not usable, resolved on the server.
+ *
+ * `unauthenticated` is kept apart from `unconfigured` because the server cannot check availability
+ * for a signed-out visitor, and telling them the instance is unconfigured would be a guess.
+ */
+export type AssistantAvailability = "enabled" | "unconfigured" | "unauthenticated" | "error";
+
+interface AssistantGateProps extends PropsWithChildren {
+  availability: AssistantAvailability;
+}
+
+const unavailableMessageKeys = {
+  unauthenticated: "unavailable.signIn",
+  unconfigured: "unavailable.notConfigured",
+  error: "unavailable.error",
+} as const;
+
+export const AssistantGate = ({ availability, children }: AssistantGateProps) => {
+  const t = useScopedI18n("common.assistant");
+
+  if (availability === "enabled") {
+    return <EnabledAssistantRoot>{children}</EnabledAssistantRoot>;
+  }
+
+  return <DisabledAssistant description={t(unavailableMessageKeys[availability])}>{children}</DisabledAssistant>;
+};