feat(api): add assigned_agent to Task model (MS22-DB-003, MS22-API-003) (#591)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/api/src/tasks/tasks.service.spec.ts

@@ -48,6 +48,7 @@ describe("TasksService", () => {
     creatorId: mockUserId,
     projectId: null,
     parentId: null,
+    assignedAgent: null,
     sortOrder: 0,
     metadata: {},
     createdAt: new Date(),
@@ -158,6 +159,28 @@ describe("TasksService", () => {
         })
       );
     });
+
+    it("should include assignedAgent when provided", async () => {
+      const createDto = {
+        title: "Agent-owned Task",
+        assignedAgent: "fleet-worker-1",
+      };
+
+      mockPrismaService.task.create.mockResolvedValue({
+        ...mockTask,
+        assignedAgent: createDto.assignedAgent,
+      });
+
+      await service.create(mockWorkspaceId, mockUserId, createDto);
+
+      expect(prisma.task.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          data: expect.objectContaining({
+            assignedAgent: createDto.assignedAgent,
+          }),
+        })
+      );
+    });
   });
 
   describe("findAll", () => {
@@ -469,6 +492,26 @@ describe("TasksService", () => {
         service.update(mockTaskId, mockWorkspaceId, mockUserId, { title: "Test" })
       ).rejects.toThrow(NotFoundException);
     });
+
+    it("should update assignedAgent when provided", async () => {
+      const updateDto = { assignedAgent: "fleet-worker-2" };
+
+      mockPrismaService.task.findUnique.mockResolvedValue(mockTask);
+      mockPrismaService.task.update.mockResolvedValue({
+        ...mockTask,
+        assignedAgent: updateDto.assignedAgent,
+      });
+
+      await service.update(mockTaskId, mockWorkspaceId, mockUserId, updateDto);
+
+      expect(prisma.task.update).toHaveBeenCalledWith(
+        expect.objectContaining({
+          data: expect.objectContaining({
+            assignedAgent: updateDto.assignedAgent,
+          }),
+        })
+      );
+    });
   });
 
   describe("remove", () => {