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internal/multiagent/eino_model_facing_trace.go

@@ -0,0 +1,84 @@
+package multiagent
+
+import (
+	"context"
+	"encoding/json"
+	"sync"
+
+	"github.com/cloudwego/eino/adk"
+)
+
+// modelFacingTraceHolder 保存「即将送入 ChatModel」的消息快照（已走 summarization / reduction / orphan 修剪等），
+// 用于 last_react_input 落库，使续跑与「上下文压缩后」的模型视角一致，而非仅依赖事件流 append 的 runAccumulatedMsgs。
+type modelFacingTraceHolder struct {
+	mu sync.Mutex
+	// msgs 为深拷贝后的切片，避免框架后续原地修改污染快照
+	msgs []adk.Message
+}
+
+func newModelFacingTraceHolder() *modelFacingTraceHolder {
+	return &modelFacingTraceHolder{}
+}
+
+// Snapshot 返回当前快照的再一次深拷贝（供序列化落库，避免与 holder 互斥长期持锁）。
+func (h *modelFacingTraceHolder) Snapshot() []adk.Message {
+	if h == nil {
+		return nil
+	}
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return cloneADKMessagesForTrace(h.msgs)
+}
+
+func (h *modelFacingTraceHolder) storeFromState(state *adk.ChatModelAgentState) {
+	if h == nil || state == nil || len(state.Messages) == 0 {
+		return
+	}
+	cloned := cloneADKMessagesForTrace(state.Messages)
+	if len(cloned) == 0 {
+		return
+	}
+	h.mu.Lock()
+	h.msgs = cloned
+	h.mu.Unlock()
+}
+
+func cloneADKMessagesForTrace(msgs []adk.Message) []adk.Message {
+	if len(msgs) == 0 {
+		return nil
+	}
+	b, err := json.Marshal(msgs)
+	if err != nil {
+		return nil
+	}
+	var out []adk.Message
+	if err := json.Unmarshal(b, &out); err != nil {
+		return nil
+	}
+	return out
+}
+
+// modelFacingTraceMiddleware 必须在 Handlers 链中处于 **BeforeModel 最后**（telemetry 之后），
+// 此时 state.Messages 即为本次 LLM 调用的最终入参。
+type modelFacingTraceMiddleware struct {
+	adk.BaseChatModelAgentMiddleware
+	holder *modelFacingTraceHolder
+}
+
+func newModelFacingTraceMiddleware(holder *modelFacingTraceHolder) adk.ChatModelAgentMiddleware {
+	if holder == nil {
+		return nil
+	}
+	return &modelFacingTraceMiddleware{holder: holder}
+}
+
+func (m *modelFacingTraceMiddleware) BeforeModelRewriteState(
+	ctx context.Context,
+	state *adk.ChatModelAgentState,
+	mc *adk.ModelContext,
+) (context.Context, *adk.ChatModelAgentState, error) {
+	if m.holder != nil && state != nil {
+		m.holder.storeFromState(state)
+	}
+	return ctx, state, nil
+}