feat(image): integrate PoloX image editing workflows

Add WaveSpeed image editing and image tools plugins, canvas image editing workflows, layer selection, and Cloud Agent image tools with approval-safe transient references.

backend/internal/protocol/image_tools_test.go

@@ -0,0 +1,53 @@
+package protocol
+
+import (
+	"context"
+	"testing"
+)
+
+func TestImageToolsProvidersBuildAsyncImageRequests(t *testing.T) {
+	cases := []struct {
+		name     string
+		provider string
+		model    string
+		path     string
+	}{
+		{name: "remove background", provider: "image-tools-remove-background", model: "bria/remove-background", path: "/bria/remove-background"},
+		{name: "layer decomposition", provider: "image-tools-layer-decomposition", model: "bytedance/seedream-v5.0-pro/layer-decomposition", path: "/bytedance/seedream-v5.0-pro/layer-decomposition"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			adapter := officialPackageAdapter(t, "image-tools.yingce-plugin", tc.provider)
+			if !adapter.Metadata().RequiresPublicMediaURLs {
+				t.Fatal("image tools must receive hydrated public image URLs")
+			}
+			created, err := adapter.BuildCreate(context.Background(), RequestContext{Request: GenerationRequest{
+				Model: tc.model,
+				Prompt: "preserve the source image while applying the requested image operation",
+				Images: []MediaReference{{URL: "https://cdn.example/source.png", Role: "edit_source", Order: 0}},
+			}})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if created.Method != "POST" || created.Path != tc.path || created.ContentType != "application/json" {
+				t.Fatalf("create request = %#v", created)
+			}
+			body := manifestTestBody(t, created)
+			if body["image"] != "https://cdn.example/source.png" {
+				t.Fatalf("source image mapping = %#v", body["image"])
+			}
+			result, err := adapter.ParseCreate(context.Background(), []byte(`{"data":{"id":"task-image-tool-1","status":"processing"}}`))
+			if err != nil || result.TaskID != "task-image-tool-1" || result.Status != StatusProcessing {
+				t.Fatalf("create result = %#v, err = %v", result, err)
+			}
+			poll, err := adapter.BuildPoll(context.Background(), PollContext{TaskID: result.TaskID})
+			if err != nil || poll.Method != "GET" || poll.Path != "/predictions/task-image-tool-1/result" {
+				t.Fatalf("poll request = %#v, err = %v", poll, err)
+			}
+			completed, err := adapter.ParsePoll(context.Background(), PollContext{TaskID: result.TaskID}, []byte(`{"data":{"id":"task-image-tool-1","status":"completed","outputs":["https://cdn.example/output.png"]}}`))
+			if err != nil || completed.Status != StatusSucceeded || completed.Result == nil || len(completed.Result.Images) != 1 || completed.Result.Images[0].URL != "https://cdn.example/output.png" {
+				t.Fatalf("poll result = %#v, err = %v", completed, err)
+			}
+		})
+	}
+}