fix: guard runtime answers with knowledge retrieval

internal/ai/runtime/executor/knowledge_guard.go

@@ -0,0 +1,60 @@
+package executor
+
+import (
+	"strings"
+
+	"cs-agent/internal/ai/runtime/internal/impl/retrievers"
+	"cs-agent/internal/models"
+	"cs-agent/internal/pkg/enums"
+
+	"github.com/cloudwego/eino/schema"
+)
+
+type knowledgeGuardDecision struct {
+	FallbackReply string
+	Instructions  []*schema.Message
+}
+
+func buildKnowledgeGuardDecision(aiAgent *models.AIAgent, retrieveResult *retrievers.KnowledgeRetrieveResult) knowledgeGuardDecision {
+	if aiAgent == nil || retrieveResult == nil || len(retrieveResult.KnowledgeBaseIDs) == 0 {
+		return knowledgeGuardDecision{}
+	}
+	fallbackReply := resolveKnowledgeFallbackReply(aiAgent, retrieveResult.FallbackMode)
+	if len(retrieveResult.Hits) == 0 {
+		return knowledgeGuardDecision{FallbackReply: fallbackReply}
+	}
+	instruction := buildKnowledgeRuntimeInstruction(retrieveResult.AnswerMode, fallbackReply)
+	if instruction == "" {
+		return knowledgeGuardDecision{}
+	}
+	return knowledgeGuardDecision{
+		Instructions: []*schema.Message{schema.SystemMessage(instruction)},
+	}
+}
+
+func resolveKnowledgeFallbackReply(aiAgent *models.AIAgent, fallbackMode enums.KnowledgeFallbackMode) string {
+	if aiAgent != nil {
+		if reply := strings.TrimSpace(aiAgent.FallbackMessage); reply != "" {
+			return reply
+		}
+	}
+	switch fallbackMode {
+	case enums.KnowledgeFallbackModeSuggestRetry:
+		return "当前知识库里没有找到足够明确的信息，你可以换个更具体的问法再试一次。"
+	case enums.KnowledgeFallbackModeTransferHuman:
+		return "当前知识库里没有找到足够明确的信息，建议转人工进一步处理。"
+	default:
+		return "当前知识库暂无明确信息。"
+	}
+}
+
+func buildKnowledgeRuntimeInstruction(answerMode enums.KnowledgeAnswerMode, fallbackReply string) string {
+	fallbackReply = strings.TrimSpace(fallbackReply)
+	if fallbackReply == "" {
+		fallbackReply = "当前知识库暂无明确信息。"
+	}
+	if answerMode == enums.KnowledgeAnswerModeAssist {
+		return "知识库回答约束：优先依据后续提供的知识片段回答，可以做轻度归纳，但不要编造片段中未提供的事实。若知识片段不足以直接支持答案，必须明确回复：" + fallbackReply
+	}
+	return "知识库回答约束：本轮只能依据后续提供的知识片段回答，不得使用模型常识补充未提供的事实。若知识片段不足以支持回答，必须明确回复：" + fallbackReply
+}