fix(cloud-agent): 布局工具参数错误按字段归类，审批卡补整理徽标

- canvas_arrange_nodes 的参数契约错误改用上游既有的 cloudAgentFieldError：
  snapshotHash 缺失按 required、mode/align/gap/nodeIds/groups 非法按 invalid_value、
  nodeIds/groups 超限按 item_count。原先一律 BadAuthRequest(*AppError)，按上游运行期的
  errors.As 顺序会走 failCloudAgentAdmission 把整轮判死，模型拿不到可纠正回执。
- 审批卡补 .canvas-agent-approval-operation-arrange_nodes 徽标配色（与新增/修改/连线同一组），
  并补一条前端用例：arrange_nodes 预览项不得被 operation() 当成未知值丢掉。

backend/internal/app/cloud_agent_layout.go

@@ -203,7 +203,7 @@ func cloudAgentArrangeMode(value string) (layout.Mode, error) {
 	case "grid":
 		return layout.ModeGrid, nil
 	default:
-		return "", BadAuthRequest("整理模式无效：只能是 auto、flow、byType、row、column 或 grid")
+		return "", cloudAgentFieldError("mode", "invalid_value", "整理模式无效：只能是 auto、flow、byType、row、column 或 grid")
 	}
 }
 
@@ -214,7 +214,7 @@ func cloudAgentArrangeAlign(value string) (layout.AlignMode, error) {
 	case "left", "centerx", "right", "top", "centery", "bottom", "distributex", "distributey":
 		return layout.AlignMode(strings.ToLower(strings.TrimSpace(value))), nil
 	default:
-		return "", BadAuthRequest("对齐模式无效：只能是 left、centerX、right、top、centerY、bottom、distributeX 或 distributeY")
+		return "", cloudAgentFieldError("align", "invalid_value", "对齐模式无效：只能是 left、centerX、right、top、centerY、bottom、distributeX 或 distributeY")
 	}
 }
 
@@ -261,7 +261,7 @@ func cloudAgentArrangeScope(doc map[string]any, args cloudAgentArrangeArgs) ([]l
 	for _, id := range requested {
 		node, ok := byID[id]
 		if !ok {
-			return nil, nil, BadAuthRequest(fmt.Sprintf("要整理的节点 %s 不存在，请重新读取画布", id))
+			return nil, nil, cloudAgentFieldError("nodeIds", "invalid_value", fmt.Sprintf("要整理的节点 %s 不在当前画布，请重新读取画布", id))
 		}
 		if node.NoMove || !cloudAgentLayoutMovable(index[id]) {
 			skipped = append(skipped, id)
@@ -320,7 +320,7 @@ func cloudAgentArrangePositions(doc map[string]any, args cloudAgentArrangeArgs,
 			bands = append(bands, layout.Band{Label: label, Nodes: members, Mode: groupMode})
 		}
 		if len(bands) == 0 {
-			return nil, nil, "", BadAuthRequest("分组里没有可整理的节点")
+			return nil, nil, "", cloudAgentFieldError("groups", "invalid_value", "分组里没有可整理的节点")
 		}
 		positions = layout.Bands(bands, args.Gap)
 	} else {
@@ -389,13 +389,13 @@ func prepareCloudAgentArrangeNodes(repo *repository.Repository, userID, canvasID
 		return nil, cloudAgentJSONArgumentError(err)
 	}
 	if strings.TrimSpace(args.SnapshotHash) == "" {
-		return nil, BadAuthRequest("整理节点需要先读取画布并传入 snapshotHash")
+		return nil, cloudAgentFieldError("snapshotHash", "required", "整理节点需要先读取画布并传入 snapshotHash")
 	}
 	if len(args.Groups) > cloudAgentArrangeMaxGroups {
-		return nil, BadAuthRequest(fmt.Sprintf("一次最多分成 %d 组", cloudAgentArrangeMaxGroups))
+		return nil, cloudAgentFieldError("groups", "item_count", fmt.Sprintf("一次最多分成 %d 组", cloudAgentArrangeMaxGroups))
 	}
 	if args.Gap < 0 || args.Gap > cloudAgentArrangeMaxGap {
-		return nil, BadAuthRequest(fmt.Sprintf("组间距必须在 0 到 %d 之间", cloudAgentArrangeMaxGap))
+		return nil, cloudAgentFieldError("gap", "invalid_value", fmt.Sprintf("组间距必须在 0 到 %d 之间", cloudAgentArrangeMaxGap))
 	}
 	canvas, err := repo.CanvasProjectForUser(userID, canvasID)
 	if err != nil {
@@ -419,10 +419,10 @@ func prepareCloudAgentArrangeNodes(repo *repository.Repository, userID, canvasID
 		return nil, err
 	}
 	if len(selected) < 2 {
-		return nil, BadAuthRequest("可整理的节点少于两个；单个节点请直接用 update_node 指定坐标")
+		return nil, cloudAgentFieldError("nodeIds", "invalid_value", "可整理的节点少于两个；单个节点请直接用 update_node 指定坐标")
 	}
 	if len(selected) > cloudAgentArrangeMaxNodes {
-		return nil, BadAuthRequest(fmt.Sprintf("一次最多整理 %d 个节点，请分批或用 nodeIds 指定范围", cloudAgentArrangeMaxNodes))
+		return nil, cloudAgentFieldError("nodeIds", "item_count", fmt.Sprintf("一次最多整理 %d 个节点，请分批或用 nodeIds 指定范围", cloudAgentArrangeMaxNodes))
 	}
 	positions, labels, mode, err := cloudAgentArrangePositions(doc, args, selected)
 	if err != nil {

backend/internal/app/cloud_agent_layout_test.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"strings"
 	"testing"
 
 	"infinite-canvas/backend/internal/canvas/layout"
@@ -228,11 +227,14 @@ func TestCloudAgentArrangeNodesRejectsStaleSnapshotAndTooManyNodes(t *testing.T)
 		many = append(many, layoutNode(fmt.Sprintf("text-%d", index), "text", float64(index), 0))
 	}
 	s2, doc2 := layoutFixture(t, many)
+	// 参数契约类错误同样按字段错误归类：模型因此拿到"哪个字段错、怎么改"的可纠正回执，
+	// 而不是被走准入失败分支判死整轮。
+	var countErr *cloudAgentFieldArgumentError
 	if _, err := applyCloudAgentArrangeNodes(s2.repo, "user", "layout-canvas", arrangeCall(t, map[string]any{
 		"snapshotHash": creationHash(doc2),
 		"mode":         "row",
-	}), mustRuntimePolicy(t, s2)); err == nil || !strings.Contains(err.Error(), "最多整理") {
-		t.Fatalf("超限应被拒绝：%v", err)
+	}), mustRuntimePolicy(t, s2)); !errors.As(err, &countErr) || countErr.Field != "nodeIds" || countErr.Issue != "item_count" {
+		t.Fatalf("超限应按 nodeIds/item_count 归类：%v", err)
 	}
 }
 

web/src/components/canvas/canvas-cloud-agent.css

@@ -931,6 +931,7 @@
 .canvas-agent-approval-operation-add_node { background: #dcfce7; color: #166534; }
 .canvas-agent-approval-operation-update_node { background: #dbeafe; color: #1d4ed8; }
 .canvas-agent-approval-operation-connect_nodes { background: #fef3c7; color: #92400e; }
+.canvas-agent-approval-operation-arrange_nodes { background: #ccfbf1; color: #115e59; }
 .canvas-agent-approval-operation-generate_media { background: #f3e8ff; color: #7e22ce; }
 
 .canvas-agent-approval-node,

web/test/agent-approval-presentation.test.ts

@@ -64,6 +64,20 @@ describe("Agent approval presentation", () => {
         expect(JSON.stringify(view)).not.toContain("private");
     });
 
+    it("keeps an arrange_nodes preview item instead of dropping it as an unknown operation", () => {
+        // 未知 operation 会被 operation() 判成 null 并丢掉整条预览项，因此新增的
+        // arrange_nodes 必须同时进联合类型与判据，否则审批卡只剩"生成"这个兜底标签。
+        const view = agentApprovalPresentation({ preview: {
+            kind: "canvas_mutation",
+            title: "确认整理画布",
+            description: "请确认要整理的节点。",
+            items: [{ operation: "arrange_nodes", nodeId: "text-1", nodeTitle: "开场分镜", nodeTypeLabel: "文本", summary: "整理《开场分镜》" }],
+        } });
+        expect(view.items).toHaveLength(1);
+        expect(view.items[0].operation).toBe("arrange_nodes");
+        expect(view.items[0].nodeTitle).toBe("开场分镜");
+    });
+
     it("states when an unknown approval cannot identify a target", () => {
         const view = agentApprovalPresentation({ toolName: "unknown_tool", arguments: {} });
         expect(view.items).toHaveLength(0);