fix(splash): select the latest history message

src/lib/chat/__tests__/splash_latest_message.test.ts

@@ -0,0 +1,41 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+import { Result } from "@/utils";
+
+const getHistoryMock = vi.hoisted(() => vi.fn());
+
+vi.mock("@/data/repositories/chat_repository", () => ({
+  getChatRepository: () => ({ getHistory: getHistoryMock }),
+}));
+
+import { fetchSplashLatestMessagePreview } from "../splash_latest_message";
+
+describe("fetchSplashLatestMessagePreview", () => {
+  beforeEach(() => {
+    getHistoryMock.mockReset();
+  });
+
+  it("uses the last message returned by history", async () => {
+    getHistoryMock.mockResolvedValue(
+      Result.ok({
+        messages: [
+          { type: "text", content: "Older message" },
+          { type: "text", content: "Latest message" },
+        ],
+      }),
+    );
+
+    const result = await fetchSplashLatestMessagePreview();
+
+    expect(getHistoryMock).toHaveBeenCalledWith(1, 0);
+    expect(Result.isOk(result) && result.data).toBe("Latest message");
+  });
+
+  it("returns null when history is empty", async () => {
+    getHistoryMock.mockResolvedValue(Result.ok({ messages: [] }));
+
+    const result = await fetchSplashLatestMessagePreview();
+
+    expect(Result.isOk(result) && result.data).toBeNull();
+  });
+});

src/lib/chat/splash_latest_message.ts

@@ -11,6 +11,6 @@ export async function fetchSplashLatestMessagePreview(): Promise<
   const result = await getChatRepository().getHistory(1, 0);
   if (Result.isErr(result)) return Result.err(result.error);
 
-  const latestMessage = result.data.messages[1] ?? null;
+  const latestMessage = result.data.messages.at(-1) ?? null;
   return Result.ok(getSplashLatestMessagePreview(latestMessage));
 }