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 });
+  });
+});

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

@@ -0,0 +1,90 @@
+import { existsSync, readFileSync } from "node:fs";
+import { join, resolve } from "node:path";
+
+type TaskViewId = string;
+
+type ManifestEntry = {
+  file?: string;
+};
+
+type ViteManifest = Record<string, ManifestEntry>;
+
+// Canonical taskView ids that map to lazy React views in App.tsx.
+// Intentionally excluded:
+// - nodes: opened by overlay state, not taskView routing
+// - todo: lazy import exists but not a valid BuiltInTaskView route
+// - board/list/graph/missions/mailbox: non-lazy views
+export const VIEW_SOURCE_MAP: Record<TaskViewId, string> = {
+  agents: "components/AgentsView.tsx",
+  chat: "components/ChatView.tsx",
+  documents: "components/DocumentsView.tsx",
+  research: "components/ResearchView.tsx",
+  evals: "components/EvalsView.tsx",
+  skills: "components/SkillsView.tsx",
+  memory: "components/MemoryView.tsx",
+  insights: "components/InsightsView.tsx",
+  reliability: "components/ReliabilityView.tsx",
+  "dev-server": "components/DevServerView.tsx",
+  goalsView: "components/GoalsView.tsx",
+  "stash-recovery": "components/StashRecoveryView.tsx",
+};
+
+const manifestCache = new Map<string, Record<TaskViewId, string>>();
+const warnedMissingManifest = new Set<string>();
+const warnedMissingEntries = new Set<string>();
+
+function warnOnce(set: Set<string>, key: string, message: string): void {
+  if (set.has(key)) {
+    return;
+  }
+  set.add(key);
+  console.warn(message);
+}
+
+export function loadViewChunkManifest(clientDir: string): Record<TaskViewId, string> {
+  const cacheKey = resolve(clientDir);
+  const cached = manifestCache.get(cacheKey);
+  if (cached) {
+    return cached;
+  }
+
+  const manifestPath = join(cacheKey, ".vite", "manifest.json");
+  if (!existsSync(manifestPath)) {
+    warnOnce(warnedMissingManifest, cacheKey, `[dashboard] View chunk manifest missing: ${manifestPath}`);
+    const empty: Record<TaskViewId, string> = {};
+    manifestCache.set(cacheKey, empty);
+    return empty;
+  }
+
+  try {
+    const manifest = JSON.parse(readFileSync(manifestPath, "utf8")) as ViteManifest;
+    const resolvedEntries: Record<TaskViewId, string> = {};
+
+    for (const [viewId, sourcePath] of Object.entries(VIEW_SOURCE_MAP)) {
+      const entry = manifest[sourcePath];
+      if (!entry?.file) {
+        warnOnce(
+          warnedMissingEntries,
+          `${cacheKey}:${viewId}`,
+          `[dashboard] View chunk manifest entry missing: ${sourcePath} (${viewId})`,
+        );
+        continue;
+      }
+      resolvedEntries[viewId] = `/${entry.file}`;
+    }
+
+    manifestCache.set(cacheKey, resolvedEntries);
+    return resolvedEntries;
+  } catch {
+    warnOnce(warnedMissingManifest, `${cacheKey}:parse`, `[dashboard] Failed to parse view chunk manifest: ${manifestPath}`);
+    const empty: Record<TaskViewId, string> = {};
+    manifestCache.set(cacheKey, empty);
+    return empty;
+  }
+}
+
+export function resetViewChunkManifestCache(): void {
+  manifestCache.clear();
+  warnedMissingManifest.clear();
+  warnedMissingEntries.clear();
+}