From c276d0c7b6c2dec4c38335355eb4a903c2379409 Mon Sep 17 00:00:00 2001
From: Christian Gunderman <gundermanc@gmail.com>
Date: Thu, 19 Feb 2026 19:06:36 +0000
Subject: [PATCH] Fix message too large issue. (#19499)

---
 packages/core/src/agents/local-executor.ts    |  7 ++++
 packages/core/src/core/client.ts              |  9 +++++
 packages/core/src/core/turn.ts                |  3 ++
 .../services/chatCompressionService.test.ts   |  4 ++-
 .../src/services/chatCompressionService.ts    | 34 ++++++++++++++++---
 5 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/packages/core/src/agents/local-executor.ts b/packages/core/src/agents/local-executor.ts
index 0d2f009a9e..bcb4e888ce 100644
--- a/packages/core/src/agents/local-executor.ts
+++ b/packages/core/src/agents/local-executor.ts
@@ -689,6 +689,13 @@ export class LocalAgentExecutor<TOutput extends z.ZodTypeAny> {
         chat.setHistory(newHistory);
         this.hasFailedCompressionAttempt = false;
       }
+    } else if (info.compressionStatus === CompressionStatus.CONTENT_TRUNCATED) {
+      if (newHistory) {
+        chat.setHistory(newHistory);
+        // Do NOT reset hasFailedCompressionAttempt.
+        // We only truncated content because summarization previously failed.
+        // We want to keep avoiding expensive summarization calls.
+      }
     }
   }
 
diff --git a/packages/core/src/core/client.ts b/packages/core/src/core/client.ts
index 951da7d6ef..0951eb397b 100644
--- a/packages/core/src/core/client.ts
+++ b/packages/core/src/core/client.ts
@@ -1082,6 +1082,15 @@ export class GeminiClient {
         this.updateTelemetryTokenCount();
         this.forceFullIdeContext = true;
       }
+    } else if (info.compressionStatus === CompressionStatus.CONTENT_TRUNCATED) {
+      if (newHistory) {
+        // We truncated content to save space, but summarization is still "failed".
+        // We update the chat context directly without resetting the failure flag.
+        this.getChat().setHistory(newHistory);
+        this.updateTelemetryTokenCount();
+        // We don't reset the chat session fully like in COMPRESSED because
+        // this is a lighter-weight intervention.
+      }
     }
 
     return info;
diff --git a/packages/core/src/core/turn.ts b/packages/core/src/core/turn.ts
index f31050dd83..b868da8e4f 100644
--- a/packages/core/src/core/turn.ts
+++ b/packages/core/src/core/turn.ts
@@ -180,6 +180,9 @@ export enum CompressionStatus {
 
   /** The compression was not necessary and no action was taken */
   NOOP,
+
+  /** The compression was skipped due to previous failure, but content was truncated to budget */
+  CONTENT_TRUNCATED,
 }
 
 export interface ChatCompressionInfo {
diff --git a/packages/core/src/services/chatCompressionService.test.ts b/packages/core/src/services/chatCompressionService.test.ts
index 39b82869bd..4ddd38e25c 100644
--- a/packages/core/src/services/chatCompressionService.test.ts
+++ b/packages/core/src/services/chatCompressionService.test.ts
@@ -226,8 +226,10 @@ describe('ChatCompressionService', () => {
       false,
       mockModel,
       mockConfig,
-      true,
+      false,
     );
+    // It should now attempt compression even if previously failed (logic removed)
+    // But since history is small, it will be NOOP due to threshold
     expect(result.info.compressionStatus).toBe(CompressionStatus.NOOP);
     expect(result.newHistory).toBeNull();
   });
diff --git a/packages/core/src/services/chatCompressionService.ts b/packages/core/src/services/chatCompressionService.ts
index 6f5366aad5..9878358966 100644
--- a/packages/core/src/services/chatCompressionService.ts
+++ b/packages/core/src/services/chatCompressionService.ts
@@ -240,10 +240,7 @@ export class ChatCompressionService {
     const curatedHistory = chat.getHistory(true);
 
     // Regardless of `force`, don't do anything if the history is empty.
-    if (
-      curatedHistory.length === 0 ||
-      (hasFailedCompressionAttempt && !force)
-    ) {
+    if (curatedHistory.length === 0) {
       return {
         newHistory: null,
         info: {
@@ -285,6 +282,35 @@ export class ChatCompressionService {
       config,
     );
 
+    // If summarization previously failed (and not forced), we only rely on truncation.
+    // We do NOT attempt to invoke the LLM for summarization again to avoid repeated failures/costs.
+    if (hasFailedCompressionAttempt && !force) {
+      const truncatedTokenCount = estimateTokenCountSync(
+        truncatedHistory.flatMap((c) => c.parts || []),
+      );
+
+      // If truncation reduced the size, we consider it a successful "compression" (truncation only).
+      if (truncatedTokenCount < originalTokenCount) {
+        return {
+          newHistory: truncatedHistory,
+          info: {
+            originalTokenCount,
+            newTokenCount: truncatedTokenCount,
+            compressionStatus: CompressionStatus.CONTENT_TRUNCATED,
+          },
+        };
+      }
+
+      return {
+        newHistory: null,
+        info: {
+          originalTokenCount,
+          newTokenCount: originalTokenCount,
+          compressionStatus: CompressionStatus.NOOP,
+        },
+      };
+    }
+
     const splitPoint = findCompressSplitPoint(
       truncatedHistory,
       1 - COMPRESSION_PRESERVE_THRESHOLD,