feat: convert file manager into a plugin

plugins/file-manager/tests/frontend/lib/file-content-request-cache.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it, vi } from "vitest";
+import {
+  getCachedFileContent,
+  invalidateCachedFileContent,
+  shouldPrefetchFileContent,
+} from "../../../src/frontend/lib/file-content-request-cache";
+
+describe("file content request cache", () => {
+  it("coalesces reads and reloads after invalidation", async () => {
+    const loader = vi.fn(async () => ({ content: "hello", path: "/note" }));
+
+    await Promise.all([
+      getCachedFileContent("session", "/note", loader),
+      getCachedFileContent("session", "/note", loader),
+    ]);
+    expect(loader).toHaveBeenCalledOnce();
+
+    invalidateCachedFileContent("session", "/note");
+    await getCachedFileContent("session", "/note", loader);
+    expect(loader).toHaveBeenCalledTimes(2);
+  });
+
+  it("only prefetches known small files on an unconstrained network", () => {
+    expect(
+      shouldPrefetchFileContent(
+        { name: "note", path: "/note", type: "file", size: 512 * 1024 },
+        512 * 1024,
+      ),
+    ).toBe(true);
+    expect(
+      shouldPrefetchFileContent(
+        { name: "large", path: "/large", type: "file", size: 512 * 1024 + 1 },
+        512 * 1024,
+      ),
+    ).toBe(false);
+    expect(
+      shouldPrefetchFileContent(
+        { name: "unknown", path: "/unknown", type: "file" },
+        512 * 1024,
+      ),
+    ).toBe(false);
+    expect(
+      shouldPrefetchFileContent(
+        { name: "note", path: "/note", type: "file", size: 100 },
+        0,
+      ),
+    ).toBe(false);
+  });
+});