feat(FN-4583): complete Step 2 — expose engine chat store accessor

Fusion-Task-Id: FN-4583
Fusion-Task-Lineage: 4d9b088d-a705-4376-b547-15b37e5370aa

packages/engine/src/__tests__/in-process-runtime.test.ts

@@ -8,4 +8,12 @@ describe("InProcessRuntime onStart duplicate guard", () => {
     expect(source).toContain("if (this.taskAgentMap.has(task.id))");
     expect(source).toContain("Skipping task-worker creation for");
   });
+
+  it("exposes getChatStore and wires HeartbeatMonitor to the runtime chatStore instance", () => {
+    const source = readFileSync(join(process.cwd(), "src/runtimes/in-process-runtime.ts"), "utf-8");
+    expect(source).toContain("this.chatStore ??= new ChatStore(this.taskStore.getFusionDir(), this.taskStore.getDatabase());");
+    expect(source).toContain("chatStore: this.chatStore,");
+    expect(source).toContain("getChatStore(): import(\"@fusion/core\").ChatStore | undefined {");
+    expect(source).toContain("return this.chatStore;");
+  });
 });

packages/engine/src/project-engine.ts

@@ -612,6 +612,11 @@ export class ProjectEngine {
     return this.runtime.getMessageStore();
   }
 
+  /** Get the ChatStore (if initialized). Returns undefined before start(). */
+  getChatStore(): import("@fusion/core").ChatStore | undefined {
+    return this.runtime.getChatStore();
+  }
+
   attachChatStore(chatStore: NotificationChatStore): void {
     this.notificationService?.attachChatStore(chatStore);
   }

packages/engine/src/runtimes/in-process-runtime.ts

@@ -1004,6 +1004,14 @@ export class InProcessRuntime
     return this.messageStore;
   }
 
+  /**
+   * Get the ChatStore instance (if initialized).
+   * Returns undefined before start() or if initialization fails.
+   */
+  getChatStore(): import("@fusion/core").ChatStore | undefined {
+    return this.chatStore;
+  }
+
   /**
    * Get the project's Scheduler instance.
    * @throws Error if runtime has not been started