feat(FN-3044): add canonical mock helpers and migrate representative test s

This merge introduces canonical mock helper modules across the dashboard and engine packages, and migrates representative test suites to use them for consistency. The changes add four new mock helpers (`mockApi.ts`, `mockLucide.ts`, `mockCore.ts`, `mockCoreEngine.ts`) and harden the API mock proxy's

Fusion-Task-Id: FN-3044

packages/engine/src/__tests__/agent-document-tools.test.ts

@@ -5,11 +5,9 @@ import {
   createTaskDocumentWriteTool,
 } from "../agent-tools.js";
 
-vi.mock("@fusion/core", async () => {
-  const actual = await vi.importActual("@fusion/core");
-  return {
-    ...actual,
-  };
+vi.mock("@fusion/core", async (importOriginal) => {
+  const { createEngineCoreMock } = await import("../test/mockCore.js");
+  return createEngineCoreMock(() => importOriginal<typeof import("@fusion/core")>());
 });
 
 const TASK_ID = "FN-1272";

packages/engine/src/__tests__/project-engine.test.ts

@@ -25,19 +25,18 @@ const mocks = vi.hoisted(() => ({
   notificationServiceStop: vi.fn(),
 }));
 
-vi.mock("@fusion/core", async () => {
-  class MockAutomationStore {
-    constructor(_cwd: string) {}
+vi.mock("@fusion/core", async (importOriginal) => {
+  const { createEngineCoreMock } = await import("../test/mockCore.js");
+  return createEngineCoreMock(() => importOriginal<typeof import("@fusion/core")>(), {
+    AutomationStore: class MockAutomationStore {
+      constructor(_cwd: string) {}
 
-    init = mocks.automationStoreInit;
-  }
-
-  return {
-    AutomationStore: MockAutomationStore,
+      init = mocks.automationStoreInit;
+    },
     syncInsightExtractionAutomation: mocks.syncInsightExtractionAutomation,
     syncAutoSummarizeAutomation: mocks.syncAutoSummarizeAutomation,
     syncMemoryDreamsAutomation: mocks.syncMemoryDreamsAutomation,
-  };
+  });
 });
 
 vi.mock("../cron-runner.js", () => {

packages/engine/src/__tests__/triage.test.ts

@@ -29,12 +29,11 @@ vi.mock("../pi.js", () => ({
   promptWithFallback: vi.fn().mockReturnValue("mock-prompt"),
 }));
 
-vi.mock("@fusion/core", async () => {
-  const actual = await vi.importActual("@fusion/core");
-  return {
-    ...actual,
+vi.mock("@fusion/core", async (importOriginal) => {
+  const { createEngineCoreMock } = await import("../test/mockCore.js");
+  return createEngineCoreMock(() => importOriginal<typeof import("@fusion/core")>(), {
     resolveAgentPrompt: vi.fn().mockReturnValue(null),
-  };
+  });
 });
 
 async function createTriageFixtureRoot(prefix: string): Promise<string> {

packages/engine/src/test/mockCore.ts

@@ -0,0 +1,21 @@
+/**
+ * Canonical @fusion/core mock helper for engine tests.
+ *
+ * Prefer extending this helper over suite-local full export lists.
+ */
+import type { Mock } from "vitest";
+
+type AnyModule = Record<string, unknown>;
+
+export async function createEngineCoreMock(
+  importActual: () => Promise<AnyModule>,
+  overrides: AnyModule = {},
+): Promise<AnyModule> {
+  const actual = await importActual();
+  return {
+    ...actual,
+    ...overrides,
+  };
+}
+
+export type MockFn = Mock;