feat: manually mirror opencoze's code from bytedance

Change-Id: I09a73aadda978ad9511264a756b2ce51f5761adf

backend/domain/agent/singleagent/internal/agentflow/node_persona_render.go

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2025 coze-dev Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package agentflow
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/cloudwego/eino/components/prompt"
+	"github.com/cloudwego/eino/schema"
+
+	"github.com/coze-dev/coze-studio/backend/pkg/lang/maps"
+)
+
+type personaRender struct {
+	persona              string
+	personaVariableNames []string
+	// variables            crossdomain.Variables
+	variables map[string]string
+}
+
+func (p *personaRender) RenderPersona(ctx context.Context, req *AgentRequest) (persona string, err error) {
+	variables := make(map[string]string, len(p.personaVariableNames))
+
+	for _, name := range p.personaVariableNames {
+		// First try to get from req.Variables
+		if val, ok := req.Variables[name]; ok {
+			variables[name] = val
+			continue
+		}
+		// Fall back to personaRender.variables
+		if val, ok := p.variables[name]; ok {
+			variables[name] = val
+			continue
+		}
+		variables[name] = ""
+	}
+
+	msgs, err := prompt.FromMessages(schema.Jinja2, schema.UserMessage(p.persona)).Format(ctx, maps.ToAnyValue(variables))
+	if err != nil {
+		return "", fmt.Errorf("render persona failed, err=%w", err)
+	}
+
+	return msgs[0].Content, nil
+}