feat(canvas): Agent 审批 - 节点直接生成时自动关闭同节点的待审批任务

用户在画布节点上直接提交生成后，同画布 Agent 对该节点等待中的 generate_media 审批关闭为 superseded_by_node，Agent 带着「用户已手动提交」的结果继续，不重复提交、不扣费。审批卡片识别目标节点正在生成时禁用「同意执行」并提示原因。

backend/internal/app/cloud_agent_node_generation_supersede_test.go

@@ -0,0 +1,135 @@
+package app
+
+import (
+	"strings"
+	"testing"
+
+	"infinite-canvas/backend/internal/model"
+)
+
+// waitingAgentMediaApproval 把 Agent 推进到“等待生成审批”，返回运行和审批 ID。
+func waitingAgentMediaApproval(t *testing.T, s *Service, a cloudAgentMediaArgs) (*model.CloudAgentExecution, string) {
+	t.Helper()
+	run, _ := agentMediaRun(t, s, a, "request_approval")
+	if err := s.advanceCloudAgentByID("user", run.ID); err != nil {
+		t.Fatal(err)
+	}
+	run, _ = s.repo.CloudAgent("user", run.ID)
+	state, err := cloudAgentDecode(run)
+	if err != nil || run.Status != "waiting_approval" || state.Approval == nil {
+		t.Fatalf("expected waiting approval: status=%s err=%v", run.Status, err)
+	}
+	return run, state.Approval.ID
+}
+
+// userNodeTaskRequest 复用 Agent 同一份生成请求，但以普通画布节点生成的身份提交。
+func userNodeTaskRequest(t *testing.T, s *Service, run *model.CloudAgentExecution, metadata map[string]any) CreateTaskRequest {
+	t.Helper()
+	state, _ := cloudAgentDecode(run)
+	req, _, err := s.prepareCloudAgentMedia(run, &state, state.Calls[state.CallIndex])
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Input["metadata"] = metadata
+	return req
+}
+
+func TestNodeGenerationSupersedesMatchingAgentApproval(t *testing.T) {
+	s, db, a := agentMediaFixture(t)
+	run, approvalID := waitingAgentMediaApproval(t, s, a)
+	req := userNodeTaskRequest(t, s, run, map[string]any{"nodeId": a.NodeID, "source": "canvas"})
+	task, err := s.CreateTask("user", req)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	run, _ = s.repo.CloudAgent("user", run.ID)
+	state, err := cloudAgentDecode(run)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if run.Status != "running" || state.Approval != nil || state.Decisions[approvalID] != cloudAgentApprovalSuperseded || state.CallIndex != 1 {
+		t.Fatalf("approval not superseded: status=%s approval=%+v decision=%q index=%d", run.Status, state.Approval, state.Decisions[approvalID], state.CallIndex)
+	}
+	decided := false
+	for _, event := range state.Events {
+		if event.Type == "approval_decided" && event.Payload["decision"] == cloudAgentApprovalSuperseded {
+			decided = event.Payload["approvalId"] == approvalID && event.Payload["taskId"] == task.ID && event.Payload["nodeId"] == a.NodeID
+		}
+	}
+	if !decided {
+		t.Fatal("missing superseded approval_decided event")
+	}
+	content, ok := cloudAgentToolMessage(&state, "media-call")
+	if !ok || !strings.Contains(content, "superseded_by_user") || !strings.Contains(content, task.ID) || cloudAgentToolContentIsError(content) {
+		t.Fatalf("tool result does not tell the Agent the user submitted: %q", content)
+	}
+	if state.MediaTaskID != "" || state.Generations != 0 {
+		t.Fatalf("Agent took over the user task: media=%s generations=%d", state.MediaTaskID, state.Generations)
+	}
+	var count, leases int64
+	db.Model(&model.Task{}).Where("type = ?", "canvas_video").Count(&count)
+	db.Model(&model.CloudAgentResourceLease{}).Where("owner_id = ?", approvalID).Count(&leases)
+	if count != 1 || leases != 0 {
+		t.Fatalf("expected only the user task and released leases: tasks=%d leases=%d", count, leases)
+	}
+
+	// 卡片上的“同意/拒绝”晚到时不能再提交任务，并给出可读原因。
+	for _, decision := range []string{"approve", "reject"} {
+		err = s.DecideCloudAgentApproval("user", run.ID, approvalID, decision, "")
+		if err == nil || !strings.Contains(err.Error(), "直接生成") {
+			t.Fatalf("late %s must be rejected with a superseded reason: %v", decision, err)
+		}
+	}
+	db.Model(&model.Task{}).Where("type = ?", "canvas_video").Count(&count)
+	if count != 1 {
+		t.Fatalf("late approval submitted a duplicate task: %d", count)
+	}
+}
+
+func TestNodeGenerationLeavesUnrelatedAgentApprovals(t *testing.T) {
+	for name, metadata := range map[string]map[string]any{
+		"other node":   {"nodeId": "hero", "source": "canvas"},
+		"no node":      {"source": "canvas"},
+		"agent origin": {"nodeId": "video-shot-1", "source": "cloud_agent"},
+	} {
+		t.Run(name, func(t *testing.T) {
+			s, _, a := agentMediaFixture(t)
+			run, approvalID := waitingAgentMediaApproval(t, s, a)
+			state, _ := cloudAgentDecode(run)
+			s.supersedeCloudAgentApprovalsForNodeTask("user", &model.Task{ID: "user-task", ProjectID: "agent-canvas"}, map[string]any{"metadata": metadata})
+			if name == "agent origin" {
+				// 显式带 AgentRunID 的任务同样跳过。
+				s.supersedeCloudAgentApprovalsForNodeTask("user", &model.Task{ID: "agent-task", ProjectID: "agent-canvas", AgentRunID: run.ID}, map[string]any{"metadata": map[string]any{"nodeId": a.NodeID}})
+			}
+			// 其他画布上的同名节点也不能关闭本画布的审批。
+			s.supersedeCloudAgentApprovalsForNodeTask("user", &model.Task{ID: "other-canvas-task", ProjectID: "other-canvas"}, map[string]any{"metadata": map[string]any{"nodeId": a.NodeID}})
+			after, _ := s.repo.CloudAgent("user", run.ID)
+			afterState, _ := cloudAgentDecode(after)
+			if after.Status != "waiting_approval" || afterState.Approval == nil || afterState.Approval.ID != approvalID || afterState.CallIndex != state.CallIndex {
+				t.Fatalf("unrelated task changed the approval: status=%s approval=%+v", after.Status, afterState.Approval)
+			}
+			if err := s.DecideCloudAgentApproval("user", run.ID, approvalID, "reject", ""); err != nil {
+				t.Fatalf("approval should still be decidable: %v", err)
+			}
+		})
+	}
+}
+
+func TestNodeGenerationSupersedeViaSourceNode(t *testing.T) {
+	s, _, a := agentMediaFixture(t)
+	run, approvalID := waitingAgentMediaApproval(t, s, a)
+	// 批量图片的结果落在新子节点，sourceNodeId 才是被审批的那个节点。
+	s.supersedeCloudAgentApprovalsForNodeTask("user", &model.Task{ID: "batch-child-task", ProjectID: "agent-canvas"}, map[string]any{"metadata": map[string]any{"nodeId": "batch-child", "sourceNodeId": a.NodeID}})
+	after, _ := s.repo.CloudAgent("user", run.ID)
+	state, _ := cloudAgentDecode(after)
+	if state.Decisions[approvalID] != cloudAgentApprovalSuperseded || state.Approval != nil {
+		t.Fatalf("sourceNodeId did not supersede the approval: %+v", state.Approval)
+	}
+	// 重复通知是幂等的：不会再写第二条工具结果。
+	s.supersedeCloudAgentApprovalsForNodeTask("user", &model.Task{ID: "batch-child-task-2", ProjectID: "agent-canvas"}, map[string]any{"metadata": map[string]any{"nodeId": a.NodeID}})
+	again, _ := s.repo.CloudAgent("user", run.ID)
+	if again.Revision != after.Revision {
+		t.Fatalf("repeated supersede mutated the run: %d -> %d", after.Revision, again.Revision)
+	}
+}