Flatten surface action data into command params

Why: system.intent ParamsSchema requires top-level text, but
SubmitAction only nested values under data, so button intent always
rejected missing text during prod acceptance.
Evidence: go test ./internal/surfacesvc/ -run TestSubmitActionFlattensDataIntoParams
Impact: B-class intent and other schema-required params work via actions;
submit still receives nested data.
Refs: GenUI prod deploy acceptance; fix track

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/surfacesvc/actions_test.go

@@ -99,6 +99,29 @@ func TestSubmitActionBClassHelpDispatches(t *testing.T) {
 	}
 }
 
+func TestSubmitActionFlattensDataIntoParams(t *testing.T) {
+	f := newActionFixture(t)
+	ctx := context.Background()
+	var params map[string]any
+	f.svc.SetDispatcher(func(ctx context.Context, d ActionDispatch) (ActionOutcome, error) {
+		params = d.Params
+		return ActionOutcome{State: "committed", Payload: map[string]any{"matched": false}}, nil
+	})
+	res, err := f.svc.SubmitAction(ctx, "alice", SubmitActionRequest{SurfaceID: f.surface.SurfaceID,
+		ActionID: "system.intent", Revision: f.rev, RequestID: "intent-1",
+		Data: map[string]any{"text": "请新建会话"}})
+	if err != nil || res.State != "committed" {
+		t.Fatalf("intent action: res=%+v err=%v", res, err)
+	}
+	if params["text"] != "请新建会话" {
+		t.Fatalf("data.text must flatten to top-level params for ParamsSchema: %+v", params)
+	}
+	data, _ := params["data"].(map[string]any)
+	if data["text"] != "请新建会话" {
+		t.Fatalf("nested data must remain for submit-shaped consumers: %+v", params)
+	}
+}
+
 func TestSubmitActionGuards(t *testing.T) {
 	f := newActionFixture(t)
 	ctx := context.Background()

internal/surfacesvc/surfacesvc.go

@@ -312,10 +312,20 @@ func (s *Service) SubmitAction(ctx context.Context, owner string, req SubmitActi
 			Note:    "幂等重放：返回已有回执",
 		}, nil
 	}
+	// 参数形态：保留 data 供 generative-ui.submit；同时把 data 键上浮到顶层，
+	// 以便 system.intent 等命令的 ParamsSchema（required: text）能直接校验。
+	params := map[string]any{
+		"surfaceId": string(req.SurfaceID), "revision": req.Revision,
+		"requestId": req.RequestID, "data": req.Data,
+	}
+	for k, v := range req.Data {
+		if k == "surfaceId" || k == "revision" || k == "requestId" || k == "data" {
+			continue
+		}
+		params[k] = v
+	}
 	out, err := s.dispatch(ctx, ActionDispatch{
-		CommandID: cmd, Owner: owner, ConversationID: rec.ConversationID,
-		Params: map[string]any{"surfaceId": string(req.SurfaceID), "revision": req.Revision,
-			"requestId": req.RequestID, "data": req.Data},
+		CommandID: cmd, Owner: owner, ConversationID: rec.ConversationID, Params: params,
 	})
 	state, cardID := out.State, out.CardID
 	if err != nil {