fix(agent): 画布助手 - 避免未支持节点阻断整张画布

backend/internal/app/cloud_agent.go

@@ -462,10 +462,13 @@ func cloudAgentCanvasSummary(canvas *model.CanvasProject) (string, error) {
 			break
 		}
 		descriptor, known := cloudAgentNodeCapabilityForType(node.Type)
-		if !known {
-			return "", BadAuthRequest("画布包含当前 Agent 不支持的节点类型")
-		}
 		item := map[string]any{"id": truncateRunes(node.ID, 100), "type": truncateRunes(node.Type, 40), "title": truncateRunes(node.Title, 300)}
+		if !known {
+			item["agentSupported"] = false
+			item["agentUnsupportedReason"] = "仅展示基础信息；当前 Agent 不支持操作此类型节点"
+			nodes = append(nodes, item)
+			continue
+		}
 		projected, err := cloudAgentProjectNodeFields(map[string]any{"title": node.Title}, node.Metadata, descriptor, descriptor.SummaryFields, 600, false, 0)
 		if err != nil {
 			return "", err

backend/internal/app/cloud_agent_canvas_state.go

@@ -86,7 +86,12 @@ func cloudAgentCanvasState(repo *repository.Repository, userID string, doc map[s
 		}
 		capability, known := cloudAgentNodeCapabilityForType(stringValue(node["type"]))
 		if !known {
-			return nil, BadAuthRequest("画布包含当前 Agent 不支持的节点类型")
+			// Read visibility is not permission to mutate or use a node as a media reference.
+			item["agentSupported"] = false
+			item["agentUnsupportedReason"] = "仅展示基础信息；当前 Agent 不支持操作此类型节点"
+			nodes = append(nodes, item)
+			included[id] = true
+			continue
 		}
 		fields := capability.SummaryFields
 		if len(ids) > 0 {

backend/internal/app/cloud_agent_contract_test.go

@@ -1,13 +1,58 @@
 package app
 
 import (
+	"encoding/json"
 	"reflect"
 	"strings"
 	"testing"
 
 	"infinite-canvas/backend/internal/canvas/capability"
+	"infinite-canvas/backend/internal/model"
 )
 
+func TestCloudAgentMixedCanvasReadsUnsupportedNodesWithoutGrantingCapabilities(t *testing.T) {
+	nodes := []map[string]any{{"id": "text", "type": "text", "metadata": map[string]any{"content": "readable"}}}
+	for _, kind := range []string{"ai-art-critique", "config", "drawing", "future-plugin"} {
+		nodes = append(nodes, map[string]any{"id": kind, "type": kind, "title": "插件节点", "position": map[string]any{"x": 10.0, "y": 20.0}, "metadata": map[string]any{"content": "PRIVATE_SENTINEL", "apiKey": "PRIVATE_SENTINEL"}})
+		if _, supported := cloudAgentNodeCapabilityForType(kind); supported {
+			t.Fatalf("unsupported type gained write capability: %s", kind)
+		}
+		if err := validateCreationOps([]CreationCanvasOp{{Type: "add_node", ID: "new", NodeType: kind}}); err == nil {
+			t.Fatalf("unsupported creation accepted: %s", kind)
+		}
+		if _, _, err := cloudAgentReferenceDescriptor(nodes[len(nodes)-1]); err == nil {
+			t.Fatalf("unsupported media reference accepted: %s", kind)
+		}
+		if err := validateCloudAgentConnection(nodes, kind, "text"); err == nil {
+			t.Fatalf("unsupported connection accepted: %s", kind)
+		}
+	}
+	doc := map[string]any{"nodes": nodes, "connections": []map[string]any{{"id": "edge", "fromNodeId": "drawing", "toNodeId": "text"}}}
+	raw, _ := json.Marshal(doc)
+	summary, err := cloudAgentCanvasSummary(&model.CanvasProject{PayloadJSON: string(raw)})
+	if err != nil || strings.Contains(summary, "PRIVATE_SENTINEL") || !strings.Contains(summary, `"agentSupported":false`) {
+		t.Fatalf("mixed summary failed or leaked metadata: %v", err)
+	}
+	for _, ids := range [][]string{nil, {"drawing", "config"}} {
+		view, err := cloudAgentCanvasState(nil, "user", doc, 0, ids, 0)
+		if err != nil {
+			t.Fatal(err)
+		}
+		result := view.(map[string]any)
+		encoded, _ := json.Marshal(result)
+		if strings.Contains(string(encoded), "PRIVATE_SENTINEL") || result["snapshotHash"] != cloudAgentCanvasHash(doc) || len(result["connections"].([]any)) != 1 {
+			t.Fatal("unsafe projection or lost snapshot/connection")
+		}
+		want := len(nodes)
+		if ids != nil {
+			want = len(ids)
+		}
+		if len(result["nodes"].([]any)) != want {
+			t.Fatal("nodes silently omitted")
+		}
+	}
+}
+
 func TestCloudAgentToolsFollowCanvasCapabilityRegistry(t *testing.T) {
 	req := agentTestRequest()
 	req.PermissionMode = "auto"