fix: context overflow compaction and subagent announce improvements (#11664) (thanks @tyler6204)

* initial commit

* feat: implement deriveSessionTotalTokens function and update usage tests

* Added deriveSessionTotalTokens function to calculate total tokens based on usage and context tokens.
* Updated usage tests to include cases for derived session total tokens.
* Refactored session usage calculations in multiple files to utilize the new function for improved accuracy.

* fix: restore overflow truncation fallback + changelog/test hardening (#11551) (thanks @tyler6204)

src/agents/pi-embedded-runner/run/attempt.ts

@@ -650,6 +650,8 @@ export async function runEmbeddedAttempt(
         getMessagingToolSentTargets,
         didSendViaMessagingTool,
         getLastToolError,
+        getUsageTotals,
+        getCompactionCount,
       } = subscription;
 
       const queueHandle: EmbeddedPiQueueHandle = {
@@ -908,6 +910,8 @@ export async function runEmbeddedAttempt(
         cloudCodeAssistFormatError: Boolean(
           lastAssistant?.errorMessage && isCloudCodeAssistFormatError(lastAssistant.errorMessage),
         ),
+        attemptUsage: getUsageTotals(),
+        compactionCount: getCompactionCount(),
         // Client tool call detected (OpenResponses hosted tools)
         clientToolCall: clientToolCallDetected ?? undefined,
       };

src/agents/pi-embedded-runner/run/types.ts

@@ -9,6 +9,7 @@ import type { MessagingToolSend } from "../../pi-embedded-messaging.js";
 import type { BlockReplyChunking, ToolResultFormat } from "../../pi-embedded-subscribe.js";
 import type { AuthStorage, ModelRegistry } from "../../pi-model-discovery.js";
 import type { SkillSnapshot } from "../../skills.js";
+import type { NormalizedUsage } from "../../usage.js";
 import type { ClientToolDefinition } from "./params.js";
 
 export type EmbeddedRunAttemptParams = {
@@ -106,6 +107,8 @@ export type EmbeddedRunAttemptResult = {
   messagingToolSentTexts: string[];
   messagingToolSentTargets: MessagingToolSend[];
   cloudCodeAssistFormatError: boolean;
+  attemptUsage?: NormalizedUsage;
+  compactionCount?: number;
   /** Client tool call detected (OpenResponses hosted tools). */
   clientToolCall?: { name: string; params: Record<string, unknown> };
 };