Version: 0.9.76.dev.260505

后端：
1.阶段 6 agent / memory 服务化收口
- 新增 cmd/agent 独立进程入口，承载 agent zrpc server、agent outbox relay / consumer 和运行时依赖初始化
- 补齐 services/agent/rpc 的 Chat stream 与 conversation meta/list/timeline、schedule-preview、context-stats、schedule-state unary RPC
- 新增 gateway/client/agent 与 shared/contracts/agent，将 /api/v1/agent chat 和非 chat 门面切到 agent zrpc
- 收缩 gateway 本地 AgentService 装配，双 RPC 开关开启时不再初始化本地 agent 编排、LLM、RAG 和 memory reader fallback
- 将 backend/memory 物理迁入 services/memory，私有实现收入 internal，保留 module/model/observe 作为 memory 服务门面
- 调整 memory outbox、memory reader 和 agent 记忆渲染链路的 import 与服务边界，cmd/memory 独占 memory worker / consumer
- 关闭 gateway 侧 agent outbox worker 所有权，agent relay / consumer 由 cmd/agent 独占，gateway 仅保留 HTTP/SSE 门面与迁移期开关回退
- 更新阶段 6 文档，记录 agent / memory 当前切流点、smoke 结果，以及 backend/client 与 gateway/shared 的目录收口口径

backend/services/memory/observe/log_fields.go

@@ -0,0 +1,119 @@
+package observe
+
+import (
+	"context"
+	"errors"
+	"strings"
+)
+
+const (
+	ComponentRead    = "read"
+	ComponentWrite   = "write"
+	ComponentInject  = "inject"
+	ComponentManage  = "manage"
+	ComponentCleanup = "cleanup"
+
+	OperationRetrieve = "retrieve"
+	OperationDecision = "decision"
+	OperationInject   = "inject"
+	OperationManage   = "manage"
+	OperationDedup    = "dedup"
+
+	MetricJobTotal               = "memory_job_total"
+	MetricJobRetryTotal          = "memory_job_retry_total"
+	MetricDecisionTotal          = "memory_decision_total"
+	MetricDecisionFallbackTotal  = "memory_decision_fallback_total"
+	MetricRetrieveHitTotal       = "memory_retrieve_hit_total"
+	MetricRetrieveDedupDropTotal = "memory_retrieve_dedup_drop_total"
+	MetricInjectItemTotal        = "memory_inject_item_total"
+	MetricRAGFallbackTotal       = "memory_rag_fallback_total"
+	MetricManageTotal            = "memory_manage_total"
+	MetricCleanupRunTotal        = "memory_cleanup_run_total"
+	MetricCleanupArchivedTotal   = "memory_cleanup_archived_total"
+)
+
+type fieldsContextKey struct{}
+
+// WithFields 把 memory 链路公共字段挂进上下文，供下游日志复用。
+//
+// 职责边界：
+// 1. 只负责字段透传与覆盖，不负责真正打印日志；
+// 2. 只保留有意义的字段，避免结构化日志长期堆积空值；
+// 3. 若上游已写入同名字段，则以后写值为准，方便链路逐层补齐上下文。
+func WithFields(ctx context.Context, fields map[string]any) context.Context {
+	if len(fields) == 0 {
+		return ctx
+	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+
+	merged := FieldsFromContext(ctx)
+	for key, value := range fields {
+		key = strings.TrimSpace(key)
+		if key == "" || !shouldKeepField(value) {
+			continue
+		}
+		merged[key] = value
+	}
+	if len(merged) == 0 {
+		return ctx
+	}
+	return context.WithValue(ctx, fieldsContextKey{}, merged)
+}
+
+// FieldsFromContext 读取当前上下文中已经累积的观测字段。
+func FieldsFromContext(ctx context.Context) map[string]any {
+	if ctx == nil {
+		return map[string]any{}
+	}
+	raw, ok := ctx.Value(fieldsContextKey{}).(map[string]any)
+	if !ok || len(raw) == 0 {
+		return map[string]any{}
+	}
+
+	result := make(map[string]any, len(raw))
+	for key, value := range raw {
+		result[key] = value
+	}
+	return result
+}
+
+// MergeFields 合并多份结构化字段，后写同名字段覆盖先写字段。
+func MergeFields(parts ...map[string]any) map[string]any {
+	result := make(map[string]any)
+	for _, part := range parts {
+		for key, value := range part {
+			key = strings.TrimSpace(key)
+			if key == "" || !shouldKeepField(value) {
+				continue
+			}
+			result[key] = value
+		}
+	}
+	return result
+}
+
+// ClassifyError 把常见错误压成稳定错误码，便于日志与指标统一聚合。
+func ClassifyError(err error) string {
+	switch {
+	case err == nil:
+		return ""
+	case errors.Is(err, context.DeadlineExceeded):
+		return "deadline_exceeded"
+	case errors.Is(err, context.Canceled):
+		return "canceled"
+	default:
+		return "memory_error"
+	}
+}
+
+func shouldKeepField(value any) bool {
+	if value == nil {
+		return false
+	}
+	if text, ok := value.(string); ok {
+		return strings.TrimSpace(text) != ""
+	}
+	return true
+}