feat(core): Land AgentHistoryProvider. (#23978)

packages/core/src/config/config.ts

@@ -681,6 +681,10 @@ export interface ConfigParameters {
   adminSkillsEnabled?: boolean;
   experimentalJitContext?: boolean;
   experimentalMemoryManager?: boolean;
+  experimentalAgentHistoryTruncation?: boolean;
+  experimentalAgentHistoryTruncationThreshold?: number;
+  experimentalAgentHistoryRetainedMessages?: number;
+  experimentalAgentHistorySummarization?: boolean;
   topicUpdateNarration?: boolean;
   toolOutputMasking?: Partial<ToolOutputMaskingConfig>;
   disableLLMCorrection?: boolean;
@@ -909,6 +913,10 @@ export class Config implements McpContext, AgentLoopContext {
 
   private readonly experimentalJitContext: boolean;
   private readonly experimentalMemoryManager: boolean;
+  private readonly experimentalAgentHistoryTruncation: boolean;
+  private readonly experimentalAgentHistoryTruncationThreshold: number;
+  private readonly experimentalAgentHistoryRetainedMessages: number;
+  private readonly experimentalAgentHistorySummarization: boolean;
   private readonly topicUpdateNarration: boolean;
   private readonly disableLLMCorrection: boolean;
   private readonly planEnabled: boolean;
@@ -1118,6 +1126,14 @@ export class Config implements McpContext, AgentLoopContext {
 
     this.experimentalJitContext = params.experimentalJitContext ?? true;
     this.experimentalMemoryManager = params.experimentalMemoryManager ?? false;
+    this.experimentalAgentHistoryTruncation =
+      params.experimentalAgentHistoryTruncation ?? false;
+    this.experimentalAgentHistoryTruncationThreshold =
+      params.experimentalAgentHistoryTruncationThreshold ?? 30;
+    this.experimentalAgentHistoryRetainedMessages =
+      params.experimentalAgentHistoryRetainedMessages ?? 15;
+    this.experimentalAgentHistorySummarization =
+      params.experimentalAgentHistorySummarization ?? false;
     this.topicUpdateNarration = params.topicUpdateNarration ?? false;
     this.modelSteering = params.modelSteering ?? false;
     this.injectionService = new InjectionService(() =>
@@ -2298,6 +2314,22 @@ export class Config implements McpContext, AgentLoopContext {
     return this.experimentalMemoryManager;
   }
 
+  isExperimentalAgentHistoryTruncationEnabled(): boolean {
+    return this.experimentalAgentHistoryTruncation;
+  }
+
+  getExperimentalAgentHistoryTruncationThreshold(): number {
+    return this.experimentalAgentHistoryTruncationThreshold;
+  }
+
+  getExperimentalAgentHistoryRetainedMessages(): number {
+    return this.experimentalAgentHistoryRetainedMessages;
+  }
+
+  isExperimentalAgentHistorySummarizationEnabled(): boolean {
+    return this.experimentalAgentHistorySummarization;
+  }
+
   isTopicUpdateNarrationEnabled(): boolean {
     return this.topicUpdateNarration;
   }

packages/core/src/config/defaultModelConfigs.ts

@@ -243,6 +243,11 @@ export const DEFAULT_MODEL_CONFIGS: ModelConfigServiceConfig = {
         model: 'gemini-3-pro-preview',
       },
     },
+    'agent-history-provider-summarizer': {
+      modelConfig: {
+        model: 'gemini-3-flash-preview',
+      },
+    },
   },
   overrides: [
     {