feat(FN-4782): complete Step 2 — add view chunk manifest helper

Fusion-Task-Id: FN-4782
Fusion-Task-Lineage: 5d6b5632-a135-4d25-9382-57fa23e22484

packages/dashboard/src/__tests__/view-chunk-manifest.test.ts

@@ -0,0 +1,95 @@
+import { mkdirSync, rmSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { afterEach, describe, expect, it } from "vitest";
+import {
+  VIEW_SOURCE_MAP,
+  loadViewChunkManifest,
+  resetViewChunkManifestCache,
+} from "../view-chunk-manifest";
+
+function makeClientDir(name: string): string {
+  return join(tmpdir(), `fn-4782-${name}-${Date.now()}-${Math.random().toString(36).slice(2)}`);
+}
+
+afterEach(() => {
+  resetViewChunkManifestCache();
+});
+
+describe("view chunk manifest", () => {
+  it("resolves hashed chunk paths", () => {
+    const clientDir = makeClientDir("resolve");
+    mkdirSync(join(clientDir, ".vite"), { recursive: true });
+    writeFileSync(
+      join(clientDir, ".vite", "manifest.json"),
+      JSON.stringify({
+        [VIEW_SOURCE_MAP.agents]: { file: "assets/AgentsView-abc123.js" },
+        [VIEW_SOURCE_MAP.chat]: { file: "assets/ChatView-def456.js" },
+      }),
+    );
+
+    const map = loadViewChunkManifest(clientDir);
+    expect(map.agents).toBe("/assets/AgentsView-abc123.js");
+    expect(map.chat).toBe("/assets/ChatView-def456.js");
+
+    rmSync(clientDir, { recursive: true, force: true });
+  });
+
+  it("returns empty map when manifest file is missing", () => {
+    const clientDir = makeClientDir("missing");
+    mkdirSync(clientDir, { recursive: true });
+
+    const map = loadViewChunkManifest(clientDir);
+    expect(map).toEqual({});
+
+    rmSync(clientDir, { recursive: true, force: true });
+  });
+
+  it("returns partial map when source entry is absent", () => {
+    const clientDir = makeClientDir("partial");
+    mkdirSync(join(clientDir, ".vite"), { recursive: true });
+    writeFileSync(
+      join(clientDir, ".vite", "manifest.json"),
+      JSON.stringify({
+        [VIEW_SOURCE_MAP.agents]: { file: "assets/AgentsView-abc123.js" },
+      }),
+    );
+
+    const map = loadViewChunkManifest(clientDir);
+    expect(map.agents).toBe("/assets/AgentsView-abc123.js");
+    expect(map.chat).toBeUndefined();
+
+    rmSync(clientDir, { recursive: true, force: true });
+  });
+
+  it("cache is invalidated by reset", () => {
+    const clientDir = makeClientDir("cache");
+    mkdirSync(join(clientDir, ".vite"), { recursive: true });
+    const manifestPath = join(clientDir, ".vite", "manifest.json");
+    writeFileSync(
+      manifestPath,
+      JSON.stringify({
+        [VIEW_SOURCE_MAP.agents]: { file: "assets/AgentsView-old.js" },
+      }),
+    );
+
+    const first = loadViewChunkManifest(clientDir);
+    expect(first.agents).toBe("/assets/AgentsView-old.js");
+
+    writeFileSync(
+      manifestPath,
+      JSON.stringify({
+        [VIEW_SOURCE_MAP.agents]: { file: "assets/AgentsView-new.js" },
+      }),
+    );
+
+    const cached = loadViewChunkManifest(clientDir);
+    expect(cached.agents).toBe("/assets/AgentsView-old.js");
+
+    resetViewChunkManifestCache();
+    const refreshed = loadViewChunkManifest(clientDir);
+    expect(refreshed.agents).toBe("/assets/AgentsView-new.js");
+
+    rmSync(clientDir, { recursive: true, force: true });
+  });
+});