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/rerank/eino_reranker.go

@@ -0,0 +1,19 @@
+package rerank
+
+import (
+	"context"
+	"errors"
+
+	"github.com/LoveLosita/smartflow/backend/services/rag/core"
+)
+
+// EinoReranker 是 Eino 重排器占位实现。
+type EinoReranker struct{}
+
+func NewEinoReranker() *EinoReranker {
+	return &EinoReranker{}
+}
+
+func (r *EinoReranker) Rerank(_ context.Context, _ string, _ []core.ScoredChunk, _ int) ([]core.ScoredChunk, error) {
+	return nil, errors.New("eino reranker is not implemented yet")
+}

backend/services/rag/rerank/noop_reranker.go

@@ -0,0 +1,30 @@
+package rerank
+
+import (
+	"context"
+	"sort"
+
+	"github.com/LoveLosita/smartflow/backend/services/rag/core"
+)
+
+// NoopReranker 是默认重排器（仅按原 score 排序）。
+type NoopReranker struct{}
+
+func NewNoopReranker() *NoopReranker {
+	return &NoopReranker{}
+}
+
+func (r *NoopReranker) Rerank(_ context.Context, _ string, candidates []core.ScoredChunk, topK int) ([]core.ScoredChunk, error) {
+	if len(candidates) == 0 {
+		return nil, nil
+	}
+	sorted := make([]core.ScoredChunk, len(candidates))
+	copy(sorted, candidates)
+	sort.SliceStable(sorted, func(i, j int) bool {
+		return sorted[i].Score > sorted[j].Score
+	})
+	if topK <= 0 || topK >= len(sorted) {
+		return sorted, nil
+	}
+	return sorted[:topK], nil
+}