diff --git a/internal/config/config.go b/internal/config/config.go
index 1c6ebc01..6d61f339 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -90,7 +90,8 @@ type MultiAgentEinoMiddlewareConfig struct {
 	SummarizationTriggerRatio float64 `yaml:"summarization_trigger_ratio,omitempty" json:"summarization_trigger_ratio,omitempty"`
 	// SummarizationEmitInternalEvents controls middleware internal event emission (default true).
 	SummarizationEmitInternalEvents *bool `yaml:"summarization_emit_internal_events,omitempty" json:"summarization_emit_internal_events,omitempty"`
-	// HistoryInputBudgetRatio caps pre-agent history tokens as max_total_tokens * ratio (default 0.35).
+	// HistoryInputBudgetRatio 已不影响 Eino：从 last_react 轨迹转 ADK 消息时**不再**按 token 比例裁剪（完整注入）。
+	// 字段仍保留，便于旧版 config 不报错；新部署可省略。
 	HistoryInputBudgetRatio float64 `yaml:"history_input_budget_ratio,omitempty" json:"history_input_budget_ratio,omitempty"`
 	// PlanExecuteUserInputBudgetRatio caps planner/replanner/executor userInput prompt budget ratio (default 0.35).
 	PlanExecuteUserInputBudgetRatio float64 `yaml:"plan_execute_user_input_budget_ratio,omitempty" json:"plan_execute_user_input_budget_ratio,omitempty"`