Version: 0.9.65.dev.260503

后端：
1. 阶段 1.5/1.6
收口 llm-service / rag-service，统一模型出口与检索基础设施入口，清退 backend/infra/llm 与 backend/infra/rag 旧实现；
2. 同步更新相关调用链与微服务迁移计划文档

backend/services/rag/retrieve/vector_retriever.go

@@ -0,0 +1,98 @@
+package retrieve
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/LoveLosita/smartflow/backend/services/rag/core"
+)
+
+// VectorRetriever 是通用检索器（embed + vector search）。
+type VectorRetriever struct {
+	embedder core.Embedder
+	store    core.VectorStore
+}
+
+func NewVectorRetriever(embedder core.Embedder, store core.VectorStore) *VectorRetriever {
+	return &VectorRetriever{
+		embedder: embedder,
+		store:    store,
+	}
+}
+
+func (r *VectorRetriever) Retrieve(ctx context.Context, req core.RetrieveRequest) (result []core.ScoredChunk, err error) {
+	defer func() {
+		recovered := recover()
+		if recovered == nil {
+			return
+		}
+		err = fmt.Errorf("vector retriever panic recovered: %v", recovered)
+	}()
+
+	if r == nil || r.embedder == nil || r.store == nil {
+		return nil, core.ErrNilDependency
+	}
+	query := strings.TrimSpace(req.Query)
+	if query == "" {
+		return nil, core.ErrInvalidQuery
+	}
+	topK := req.TopK
+	if topK <= 0 {
+		topK = 8
+	}
+	action := strings.TrimSpace(req.Action)
+	if action == "" {
+		action = "search"
+	}
+
+	vectors, err := r.embedder.Embed(ctx, []string{query}, action)
+	if err != nil {
+		return nil, err
+	}
+	if len(vectors) != 1 {
+		return nil, fmt.Errorf("embedding query length mismatch: %d", len(vectors))
+	}
+
+	rows, err := r.store.Search(ctx, core.VectorSearchRequest{
+		QueryVector: vectors[0],
+		TopK:        topK,
+		Filter:      req.Filter,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	result = make([]core.ScoredChunk, 0, len(rows))
+	for _, row := range rows {
+		if row.Score < req.Threshold {
+			continue
+		}
+		result = append(result, core.ScoredChunk{
+			ChunkID:    row.Row.ID,
+			DocumentID: asString(row.Row.Metadata["document_id"]),
+			Text:       row.Row.Text,
+			Score:      row.Score,
+			Metadata:   cloneMap(row.Row.Metadata),
+		})
+	}
+	return result, nil
+}
+
+func cloneMap(src map[string]any) map[string]any {
+	if len(src) == 0 {
+		return map[string]any{}
+	}
+	dst := make(map[string]any, len(src))
+	for k, v := range src {
+		dst[k] = v
+	}
+	return dst
+}
+
+func asString(v any) string {
+	if v == nil {
+		return ""
+	}
+	return fmt.Sprintf("%v", v)
+}