diff --git a/packages/cli/src/acp-integration/session/Session.test.ts b/packages/cli/src/acp-integration/session/Session.test.ts
index afd28a48bcd..0c6d566543e 100644
--- a/packages/cli/src/acp-integration/session/Session.test.ts
+++ b/packages/cli/src/acp-integration/session/Session.test.ts
@@ -33247,65 +33247,70 @@ describe('Session', () => {
       expect(mockChat.sendMessageStream).toHaveBeenCalledTimes(2);
     });
 
-    it('does not count a failed Guard compression or block later automatic work', async () => {
-      rebuildSessionWithGuard();
-      installPendingTodoTool();
-      queuePendingTodoThenNaturalStops();
-      const noCompression = {
-        originalTokenCount: 50,
-        newTokenCount: 50,
-        compressionStatus: core.CompressionStatus.NOOP,
-      };
-      mockLlmClient.tryCompressChat
-        .mockResolvedValueOnce(noCompression)
-        .mockResolvedValueOnce(noCompression)
-        .mockResolvedValueOnce({
-          originalTokenCount: 120,
-          newTokenCount: 120,
-          compressionStatus:
-            core.CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY,
-        })
-        .mockResolvedValue(noCompression);
+    it.each([
+      core.CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY,
+      core.CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+    ])(
+      'does not count a failed Guard compression status %s or block later automatic work',
+      async (compressionStatus) => {
+        rebuildSessionWithGuard();
+        installPendingTodoTool();
+        queuePendingTodoThenNaturalStops();
+        const noCompression = {
+          originalTokenCount: 50,
+          newTokenCount: 50,
+          compressionStatus: core.CompressionStatus.NOOP,
+        };
+        mockLlmClient.tryCompressChat
+          .mockResolvedValueOnce(noCompression)
+          .mockResolvedValueOnce(noCompression)
+          .mockResolvedValueOnce({
+            originalTokenCount: 120,
+            newTokenCount: 120,
+            compressionStatus,
+          })
+          .mockResolvedValue(noCompression);
 
-      await runGuardPrompt();
+        await runGuardPrompt();
 
-      expect(mockChat.sendMessageStream).toHaveBeenCalledTimes(2);
-      expect(
-        vi
-          .mocked(mockClient.sessionUpdate)
-          .mock.calls.some(
-            ([params]) =>
-              params.update.sessionUpdate === 'agent_message_chunk' &&
-              params.update._meta?.['source'] === 'todo_stop_guard',
-          ),
-      ).toBe(false);
+        expect(mockChat.sendMessageStream).toHaveBeenCalledTimes(2);
+        expect(
+          vi
+            .mocked(mockClient.sessionUpdate)
+            .mock.calls.some(
+              ([params]) =>
+                params.update.sessionUpdate === 'agent_message_chunk' &&
+                params.update._meta?.['source'] === 'todo_stop_guard',
+            ),
+        ).toBe(false);
 
-      const callback =
-        mockBackgroundTaskRegistry.setNotificationCallback.mock.calls.at(
-          -1,
-        )?.[0] as (
-          displayText: string,
-          modelText: string,
-          meta: { agentId: string; status: string },
-        ) => void;
-      callback('independent background done', '<task-notification />', {
-        agentId: 'after-guard-compression-failure',
-        status: 'completed',
-      });
+        const callback =
+          mockBackgroundTaskRegistry.setNotificationCallback.mock.calls.at(
+            -1,
+          )?.[0] as (
+            displayText: string,
+            modelText: string,
+            meta: { agentId: string; status: string },
+          ) => void;
+        callback('independent background done', '<task-notification />', {
+          agentId: 'after-guard-compression-failure',
+          status: 'completed',
+        });
 
-      await vi.waitFor(() => {
-        expect(mockChat.sendMessageStream).toHaveBeenCalledTimes(3);
-      });
-      expect(
-        vi
-          .mocked(mockClient.sessionUpdate)
-          .mock.calls.some(
-            ([params]) =>
-              params.update.sessionUpdate === 'agent_message_chunk' &&
-              params.update._meta?.['source'] === 'todo_stop_guard',
-          ),
-      ).toBe(false);
-    });
+        await vi.waitFor(() => {
+          expect(mockChat.sendMessageStream).toHaveBeenCalledTimes(3);
+        });
+        expect(
+          vi
+            .mocked(mockClient.sessionUpdate)
+            .mock.calls.some(
+              ([params]) =>
+                params.update.sessionUpdate === 'agent_message_chunk' &&
+                params.update._meta?.['source'] === 'todo_stop_guard',
+            ),
+        ).toBe(false);
+      },
+    );
 
     it('keeps external Stop hook continuation when Guard compression throws', async () => {
       rebuildSessionWithGuard();
diff --git a/packages/cli/src/acp-integration/session/Session.ts b/packages/cli/src/acp-integration/session/Session.ts
index 2e19ef3935a..0a62a6418b0 100644
--- a/packages/cli/src/acp-integration/session/Session.ts
+++ b/packages/cli/src/acp-integration/session/Session.ts
@@ -58,6 +58,7 @@ import {
   AuthType,
   ApprovalMode,
   CompressionStatus,
+  isCompressionFailureStatus,
   RUNTIME_SNAPSHOT_PREFIX,
   detectLoopSentinel,
   detectAutonomousSentinel,
@@ -451,15 +452,6 @@ function isTodoStopGuardPromptText(text: unknown): text is string {
   );
 }
 
-function isCompressionFailureStatus(status: CompressionStatus): boolean {
-  return (
-    status === CompressionStatus.COMPRESSION_FAILED_INFLATED_TOKEN_COUNT ||
-    status === CompressionStatus.COMPRESSION_FAILED_TOKEN_COUNT_ERROR ||
-    status === CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY ||
-    status === CompressionStatus.COMPRESSION_FAILED_OUTPUT_TRUNCATED
-  );
-}
-
 /** Finalizes preparations without allowing ACP cleanup to change the stream outcome. */
 async function finalizeToolCallPreparations(
   tracker: ToolCallPreparationTracker,
diff --git a/packages/cli/src/i18n/locales/ca.js b/packages/cli/src/i18n/locales/ca.js
index 23cc0350e0c..1d3192c546a 100644
--- a/packages/cli/src/i18n/locales/ca.js
+++ b/packages/cli/src/i18n/locales/ca.js
@@ -1179,6 +1179,12 @@ export default {
     "La compressió de l'historial del xat no ha reduït la mida. Això pot indicar problemes amb el missatge de compressió.",
   'Could not compress chat history due to a token counting error.':
     "No s'ha pogut comprimir l'historial del xat per un error de recompte de tokens.",
+  'Could not compress chat history because the compression summary was empty.':
+    "No s'ha pogut comprimir l'historial del xat perquè el resum de compressió era buit.",
+  'Could not compress chat history because the compression summary was truncated.':
+    "No s'ha pogut comprimir l'historial del xat perquè el resum de compressió s'ha truncat.",
+  'Could not compress chat history due to an API error.':
+    "No s'ha pogut comprimir l'historial del xat per un error de l'API.",
   // ============================================================================
   // Ordres - Directori
   // ============================================================================
diff --git a/packages/cli/src/i18n/locales/de.js b/packages/cli/src/i18n/locales/de.js
index f3589ab1083..3f6f7d711e9 100644
--- a/packages/cli/src/i18n/locales/de.js
+++ b/packages/cli/src/i18n/locales/de.js
@@ -1057,6 +1057,12 @@ export default {
     'Chatverlauf-Komprimierung hat die Größe nicht reduziert. Dies kann auf Probleme mit dem Komprimierungs-Prompt hindeuten.',
   'Could not compress chat history due to a token counting error.':
     'Chatverlauf konnte aufgrund eines Token-Zählfehlers nicht komprimiert werden.',
+  'Could not compress chat history because the compression summary was empty.':
+    'Chatverlauf konnte nicht komprimiert werden, da die Komprimierungszusammenfassung leer war.',
+  'Could not compress chat history because the compression summary was truncated.':
+    'Chatverlauf konnte nicht komprimiert werden, da die Komprimierungszusammenfassung abgeschnitten wurde.',
+  'Could not compress chat history due to an API error.':
+    'Chatverlauf konnte aufgrund eines API-Fehlers nicht komprimiert werden.',
   // ============================================================================
   // Commands - Directory
   // ============================================================================
diff --git a/packages/cli/src/i18n/locales/en.js b/packages/cli/src/i18n/locales/en.js
index a91b8db0220..18243b98371 100644
--- a/packages/cli/src/i18n/locales/en.js
+++ b/packages/cli/src/i18n/locales/en.js
@@ -1621,6 +1621,12 @@ export default {
     'Chat history compression did not reduce size. This may indicate issues with the compression prompt.',
   'Could not compress chat history due to a token counting error.':
     'Could not compress chat history due to a token counting error.',
+  'Could not compress chat history because the compression summary was empty.':
+    'Could not compress chat history because the compression summary was empty.',
+  'Could not compress chat history because the compression summary was truncated.':
+    'Could not compress chat history because the compression summary was truncated.',
+  'Could not compress chat history due to an API error.':
+    'Could not compress chat history due to an API error.',
   // ============================================================================
   // Commands - Directory
   // ============================================================================
diff --git a/packages/cli/src/i18n/locales/fr.js b/packages/cli/src/i18n/locales/fr.js
index 05fb30ba605..aa47c76457a 100644
--- a/packages/cli/src/i18n/locales/fr.js
+++ b/packages/cli/src/i18n/locales/fr.js
@@ -1187,6 +1187,12 @@ export default {
     "La compression de l'historique du chat n'a pas réduit la taille. Cela peut indiquer des problèmes avec l'invite de compression.",
   'Could not compress chat history due to a token counting error.':
     "Impossible de compresser l'historique du chat en raison d'une erreur de comptage de tokens.",
+  'Could not compress chat history because the compression summary was empty.':
+    "Impossible de compresser l'historique du chat, car le résumé de compression était vide.",
+  'Could not compress chat history because the compression summary was truncated.':
+    "Impossible de compresser l'historique du chat, car le résumé de compression a été tronqué.",
+  'Could not compress chat history due to an API error.':
+    "Impossible de compresser l'historique du chat en raison d'une erreur d'API.",
   // ============================================================================
   // Commandes - Répertoire
   // ============================================================================
diff --git a/packages/cli/src/i18n/locales/ja.js b/packages/cli/src/i18n/locales/ja.js
index a500bb69fab..911a9925e50 100644
--- a/packages/cli/src/i18n/locales/ja.js
+++ b/packages/cli/src/i18n/locales/ja.js
@@ -816,6 +816,12 @@ export default {
     'チャット履歴の圧縮でサイズが減少しませんでした。圧縮プロンプトに問題がある可能性があります',
   'Could not compress chat history due to a token counting error.':
     'トークンカウントエラーのため、チャット履歴を圧縮できませんでした',
+  'Could not compress chat history because the compression summary was empty.':
+    '圧縮サマリーが空だったため、チャット履歴を圧縮できませんでした',
+  'Could not compress chat history because the compression summary was truncated.':
+    '圧縮サマリーが切り詰められたため、チャット履歴を圧縮できませんでした',
+  'Could not compress chat history due to an API error.':
+    'API エラーのため、チャット履歴を圧縮できませんでした',
   // Directory
   'Configuration is not available.': '設定が利用できません',
   'Please provide at least one path to add.':
diff --git a/packages/cli/src/i18n/locales/pt.js b/packages/cli/src/i18n/locales/pt.js
index 8553bee5f45..61c278b14fa 100644
--- a/packages/cli/src/i18n/locales/pt.js
+++ b/packages/cli/src/i18n/locales/pt.js
@@ -1060,6 +1060,12 @@ export default {
     'A compressão do histórico do chat não reduziu o tamanho. Isso pode indicar problemas com o prompt de compressão.',
   'Could not compress chat history due to a token counting error.':
     'Não foi possível comprimir o histórico do chat devido a um erro de contagem de tokens.',
+  'Could not compress chat history because the compression summary was empty.':
+    'Não foi possível comprimir o histórico do chat porque o resumo da compressão estava vazio.',
+  'Could not compress chat history because the compression summary was truncated.':
+    'Não foi possível comprimir o histórico do chat porque o resumo da compressão foi truncado.',
+  'Could not compress chat history due to an API error.':
+    'Não foi possível comprimir o histórico do chat devido a um erro da API.',
   // ============================================================================
   // Commands - Directory
   // ============================================================================
diff --git a/packages/cli/src/i18n/locales/ru.js b/packages/cli/src/i18n/locales/ru.js
index 97938379fe8..2b1d2d774bb 100644
--- a/packages/cli/src/i18n/locales/ru.js
+++ b/packages/cli/src/i18n/locales/ru.js
@@ -1066,6 +1066,12 @@ export default {
     'Сжатие истории чата не уменьшило размер. Это может указывать на проблемы с промптом сжатия.',
   'Could not compress chat history due to a token counting error.':
     'Не удалось сжать историю чата из-за ошибки подсчета токенов.',
+  'Could not compress chat history because the compression summary was empty.':
+    'Не удалось сжать историю чата, потому что сводка сжатия была пустой.',
+  'Could not compress chat history because the compression summary was truncated.':
+    'Не удалось сжать историю чата, потому что сводка сжатия была усечена.',
+  'Could not compress chat history due to an API error.':
+    'Не удалось сжать историю чата из-за ошибки API.',
   // ============================================================================
   // Команды - Директория
   // ============================================================================
diff --git a/packages/cli/src/i18n/locales/zh-TW.js b/packages/cli/src/i18n/locales/zh-TW.js
index 758527c27d4..1dfcb1c6c98 100644
--- a/packages/cli/src/i18n/locales/zh-TW.js
+++ b/packages/cli/src/i18n/locales/zh-TW.js
@@ -1424,6 +1424,12 @@ export default {
     '聊天歷史壓縮未能減小大小。這可能表明壓縮提示存在問題。',
   'Could not compress chat history due to a token counting error.':
     '由於 token 計數錯誤，無法壓縮聊天歷史。',
+  'Could not compress chat history because the compression summary was empty.':
+    '由於壓縮摘要為空，無法壓縮聊天歷史。',
+  'Could not compress chat history because the compression summary was truncated.':
+    '由於壓縮摘要被截斷，無法壓縮聊天歷史。',
+  'Could not compress chat history due to an API error.':
+    '由於 API 錯誤，無法壓縮聊天歷史。',
   'Configuration is not available.': '配置不可用。',
   'Please provide at least one path to add.': '請提供至少一個要添加的路徑。',
   'The /directory add command is not supported in restrictive sandbox profiles. Please use --include-directories when starting the session instead.':
diff --git a/packages/cli/src/i18n/locales/zh.js b/packages/cli/src/i18n/locales/zh.js
index 58f179d6a81..36d926a0ce5 100644
--- a/packages/cli/src/i18n/locales/zh.js
+++ b/packages/cli/src/i18n/locales/zh.js
@@ -1546,6 +1546,12 @@ export default {
     '聊天历史压缩未能减小大小。这可能表明压缩提示存在问题。',
   'Could not compress chat history due to a token counting error.':
     '由于 token 计数错误，无法压缩聊天历史。',
+  'Could not compress chat history because the compression summary was empty.':
+    '由于压缩摘要为空，无法压缩聊天历史。',
+  'Could not compress chat history because the compression summary was truncated.':
+    '由于压缩摘要被截断，无法压缩聊天历史。',
+  'Could not compress chat history due to an API error.':
+    '由于 API 错误，无法压缩聊天历史。',
   // ============================================================================
   // Commands - Directory
   // ============================================================================
diff --git a/packages/cli/src/ui/commands/compressCommand.test.ts b/packages/cli/src/ui/commands/compressCommand.test.ts
index d48c9c5e3b0..ff89a669eab 100644
--- a/packages/cli/src/ui/commands/compressCommand.test.ts
+++ b/packages/cli/src/ui/commands/compressCommand.test.ts
@@ -133,6 +133,31 @@ describe('compressCommand', () => {
     expect(context.ui.setPendingItem).toHaveBeenCalledWith(null);
   });
 
+  it('should keep compression failure statuses in the interactive history', async () => {
+    const failedResult: ChatCompressionInfo = {
+      originalTokenCount: 100000,
+      newTokenCount: 100000,
+      compressionStatus: CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+    };
+    mockTryCompressChat.mockResolvedValue(failedResult);
+
+    await compressCommand.action!(context, '');
+
+    expect(context.ui.addItem).toHaveBeenCalledWith(
+      {
+        type: MessageType.COMPRESSION,
+        compression: {
+          isPending: false,
+          compressionStatus: CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+          originalTokenCount: 100000,
+          newTokenCount: 100000,
+          compressionKind: 'summarize',
+        },
+      },
+      expect.any(Number),
+    );
+  });
+
   // Issue #9309: after /compress-fast the summarize banner is measured on a
   // different scale (local history-only estimate vs the fast banner's
   // API-reported baseline), so the compression item must carry per-side
@@ -166,6 +191,56 @@ describe('compressCommand', () => {
     );
   });
 
+  it('should return an error in non-interactive mode for compression failure statuses', async () => {
+    const failedResult: ChatCompressionInfo = {
+      originalTokenCount: 100000,
+      newTokenCount: 100000,
+      compressionStatus: CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+    };
+    mockTryCompressChat.mockResolvedValue(failedResult);
+    const ctx = createMockCommandContext({
+      executionMode: 'non_interactive',
+      services: context.services,
+    });
+
+    await expect(compressCommand.action!(ctx, '')).resolves.toEqual({
+      type: 'message',
+      messageType: 'error',
+      content: 'Could not compress chat history due to an API error.',
+    });
+  });
+
+  it('should yield an ACP error for compression failure statuses', async () => {
+    const failedResult: ChatCompressionInfo = {
+      originalTokenCount: 100000,
+      newTokenCount: 100000,
+      compressionStatus: CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+    };
+    mockTryCompressChat.mockResolvedValue(failedResult);
+    const ctx = createMockCommandContext({
+      executionMode: 'acp',
+      services: context.services,
+    });
+
+    const result = await compressCommand.action!(ctx, '');
+    expect(result?.type).toBe('stream_messages');
+
+    const messages = [];
+    if (result?.type === 'stream_messages') {
+      for await (const message of result.messages) {
+        messages.push(message);
+      }
+    }
+
+    expect(messages).toEqual([
+      { messageType: 'info', content: 'Compressing context...' },
+      {
+        messageType: 'error',
+        content: 'Could not compress chat history due to an API error.',
+      },
+    ]);
+  });
+
   it('should mark estimated counts in the non-interactive message', async () => {
     // Asymmetric flags mirror the real post-/compress-fast scenario and catch
     // a swapped flag-argument mutation at the formatTokenCount call sites.
diff --git a/packages/cli/src/ui/commands/compressCommand.ts b/packages/cli/src/ui/commands/compressCommand.ts
index 182818ff08a..2620fec7b33 100644
--- a/packages/cli/src/ui/commands/compressCommand.ts
+++ b/packages/cli/src/ui/commands/compressCommand.ts
@@ -5,10 +5,15 @@
  */
 
 import type { HistoryItemCompression } from '../types.js';
+import { isCompressionFailureStatus } from '@qwen-code/qwen-code-core';
 import { MessageType } from '../types.js';
 import type { SlashCommand } from './types.js';
 import { CommandKind } from './types.js';
 import { t } from '../../i18n/index.js';
+import {
+  formatCompressionTokenCount,
+  getCompressionFailureStatusText,
+} from '../utils/compression-text.js';
 
 // Cap user-supplied compression instructions. The compression side-query has
 // no input-truncation retry today, so an unbounded instruction string would
@@ -17,11 +22,6 @@ import { t } from '../../i18n/index.js';
 // without exposing that failure mode.
 const MAX_COMPRESS_INSTRUCTIONS_CHARS = 2000;
 
-// Estimated counts (#9309) get a '~' prefix so structured/headless consumers
-// don't treat locally estimated numbers as API-reported token counts.
-const formatTokenCount = (count: number, isEstimated?: boolean) =>
-  isEstimated ? `~${count}` : String(count);
-
 export const compressCommand: SlashCommand = {
   name: 'compress',
   altNames: ['summarize'],
@@ -104,17 +104,25 @@ export const compressCommand: SlashCommand = {
             content: 'Compressing context...',
           };
           const compressed = await doCompress();
-          if (!compressed) {
+          if (
+            !compressed ||
+            isCompressionFailureStatus(compressed.compressionStatus)
+          ) {
             yield {
               messageType: 'error' as const,
-              content: t('Failed to compress chat history.'),
+              content: compressed
+                ? getCompressionFailureStatusText({
+                    compressionStatus: compressed.compressionStatus,
+                    originalTokenCount: compressed.originalTokenCount,
+                  })
+                : t('Failed to compress chat history.'),
             };
             return;
           }
           yield {
             messageType: 'info' as const,
             content:
-              `Context compressed (${formatTokenCount(compressed.originalTokenCount, compressed.originalTokenCountIsEstimated)} -> ${formatTokenCount(compressed.newTokenCount, compressed.newTokenCountIsEstimated)}).` +
+              `Context compressed (${formatCompressionTokenCount(compressed.originalTokenCount, compressed.originalTokenCountIsEstimated)} -> ${formatCompressionTokenCount(compressed.newTokenCount, compressed.newTokenCountIsEstimated)}).` +
               (compressed.warning ? `\n⚠️ ${compressed.warning}` : ''),
           };
         } catch (e) {
@@ -147,7 +155,11 @@ export const compressCommand: SlashCommand = {
         return;
       }
 
-      if (!compressed) {
+      if (
+        !compressed ||
+        (executionMode !== 'interactive' &&
+          isCompressionFailureStatus(compressed.compressionStatus))
+      ) {
         if (executionMode === 'interactive') {
           ui.addItem(
             {
@@ -162,7 +174,12 @@ export const compressCommand: SlashCommand = {
         return {
           type: 'message',
           messageType: 'error',
-          content: t('Failed to compress chat history.'),
+          content: compressed
+            ? getCompressionFailureStatusText({
+                compressionStatus: compressed.compressionStatus,
+                originalTokenCount: compressed.originalTokenCount,
+              })
+            : t('Failed to compress chat history.'),
         };
       }
 
@@ -196,7 +213,7 @@ export const compressCommand: SlashCommand = {
         type: 'message',
         messageType: 'info',
         content:
-          `${truncationNotice ? `${truncationNotice} ` : ''}Context compressed (${formatTokenCount(compressed.originalTokenCount, compressed.originalTokenCountIsEstimated)} -> ${formatTokenCount(compressed.newTokenCount, compressed.newTokenCountIsEstimated)}).` +
+          `${truncationNotice ? `${truncationNotice} ` : ''}Context compressed (${formatCompressionTokenCount(compressed.originalTokenCount, compressed.originalTokenCountIsEstimated)} -> ${formatCompressionTokenCount(compressed.newTokenCount, compressed.newTokenCountIsEstimated)}).` +
           (compressed.warning ? `\n⚠️ ${compressed.warning}` : ''),
       };
     } catch (e) {
diff --git a/packages/cli/src/ui/components/messages/CompressionMessage.test.tsx b/packages/cli/src/ui/components/messages/CompressionMessage.test.tsx
index 1b48636b6eb..b52276c7c36 100644
--- a/packages/cli/src/ui/components/messages/CompressionMessage.test.tsx
+++ b/packages/cli/src/ui/components/messages/CompressionMessage.test.tsx
@@ -237,5 +237,51 @@ describe('<CompressionMessage />', () => {
         expect(output).not.toContain('Compression was not beneficial');
       });
     });
+
+    it('shows API error message when compression side-query fails', () => {
+      const props = createCompressionProps({
+        isPending: false,
+        originalTokenCount: 100000,
+        newTokenCount: 100000,
+        compressionStatus: CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+      });
+      const { lastFrame } = render(<CompressionMessage {...props} />);
+      const output = lastFrame();
+
+      expect(output).toContain(
+        'Could not compress chat history due to an API error.',
+      );
+    });
+
+    it('shows empty summary failure message', () => {
+      const props = createCompressionProps({
+        isPending: false,
+        originalTokenCount: 100000,
+        newTokenCount: 0,
+        compressionStatus: CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY,
+      });
+      const { lastFrame } = render(<CompressionMessage {...props} />);
+      const output = lastFrame();
+
+      expect(output).toContain(
+        'Could not compress chat history because the compression summary was empty.',
+      );
+    });
+
+    it('shows truncated output failure message', () => {
+      const props = createCompressionProps({
+        isPending: false,
+        originalTokenCount: 100000,
+        newTokenCount: 0,
+        compressionStatus:
+          CompressionStatus.COMPRESSION_FAILED_OUTPUT_TRUNCATED,
+      });
+      const { lastFrame } = render(<CompressionMessage {...props} />);
+      const output = lastFrame();
+
+      expect(output).toContain(
+        'Could not compress chat history because the compression summary was truncated.',
+      );
+    });
   });
 });
diff --git a/packages/cli/src/ui/components/messages/CompressionMessage.tsx b/packages/cli/src/ui/components/messages/CompressionMessage.tsx
index 9e0e536e979..298bcea6fa7 100644
--- a/packages/cli/src/ui/components/messages/CompressionMessage.tsx
+++ b/packages/cli/src/ui/components/messages/CompressionMessage.tsx
@@ -9,9 +9,8 @@ import type { CompressionProps } from '../../types.js';
 import Spinner from 'ink-spinner';
 import { theme } from '../../semantic-colors.js';
 import { SCREEN_READER_MODEL_PREFIX } from '../../textConstants.js';
-import { CompressionStatus } from '@qwen-code/qwen-code-core';
-import { t } from '../../../i18n/index.js';
 import { ICON } from '../../constants.js';
+import { getCompressionStatusText } from '../../utils/compression-text.js';
 
 export interface CompressionDisplayProps {
   compression: CompressionProps;
@@ -33,54 +32,14 @@ export function CompressionMessage({
     newTokenCountIsEstimated,
   } = compression;
 
-  const originalTokens = originalTokenCount ?? 0;
-  const newTokens = newTokenCount ?? 0;
-
-  // Estimated counts (#9309): the two compression paths measure on different
-  // scales, so a '~' prefix marks which banner numbers are local estimates
-  // rather than API-reported counts.
-  const formatTokens = (count: number, isEstimated?: boolean) =>
-    isEstimated ? `~${count}` : String(count);
-
-  const getCompressionText = () => {
-    if (isPending) {
-      return t('Compressing chat history');
-    }
-
-    switch (compressionStatus) {
-      case CompressionStatus.COMPRESSED:
-        return t(
-          'Chat history compressed from {{originalTokens}} to {{newTokens}} tokens.',
-          {
-            originalTokens: formatTokens(
-              originalTokens,
-              originalTokenCountIsEstimated,
-            ),
-            newTokens: formatTokens(newTokens, newTokenCountIsEstimated),
-          },
-        );
-      case CompressionStatus.COMPRESSION_FAILED_INFLATED_TOKEN_COUNT:
-        // For smaller histories (< 50k tokens), compression overhead likely exceeds benefits
-        if (originalTokens < 50000) {
-          return t('Compression was not beneficial for this history size.');
-        }
-        // For larger histories where compression should work but didn't,
-        // this suggests an issue with the compression process itself
-        return t(
-          'Chat history compression did not reduce size. This may indicate issues with the compression prompt.',
-        );
-      case CompressionStatus.COMPRESSION_FAILED_TOKEN_COUNT_ERROR:
-        return t(
-          'Could not compress chat history due to a token counting error.',
-        );
-      case CompressionStatus.NOOP:
-        return 'Nothing to compress.';
-      default:
-        return '';
-    }
-  };
-
-  const text = getCompressionText();
+  const text = getCompressionStatusText({
+    isPending,
+    originalTokenCount,
+    newTokenCount,
+    compressionStatus,
+    originalTokenCountIsEstimated,
+    newTokenCountIsEstimated,
+  });
 
   return (
     <Box flexDirection="row">
diff --git a/packages/cli/src/ui/utils/compression-text.ts b/packages/cli/src/ui/utils/compression-text.ts
new file mode 100644
index 00000000000..34df613a08d
--- /dev/null
+++ b/packages/cli/src/ui/utils/compression-text.ts
@@ -0,0 +1,99 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+  CompressionStatus,
+  isCompressionFailureStatus,
+} from '@qwen-code/qwen-code-core';
+import { t } from '../../i18n/index.js';
+
+export const formatCompressionTokenCount = (
+  count: number,
+  isEstimated?: boolean,
+) => (isEstimated ? `~${count}` : String(count));
+
+export interface CompressionStatusTextOptions {
+  isPending?: boolean;
+  originalTokenCount?: number | null;
+  newTokenCount?: number | null;
+  compressionStatus?: CompressionStatus | null;
+  originalTokenCountIsEstimated?: boolean;
+  newTokenCountIsEstimated?: boolean;
+}
+
+export function getCompressionStatusText({
+  isPending,
+  originalTokenCount,
+  newTokenCount,
+  compressionStatus,
+  originalTokenCountIsEstimated,
+  newTokenCountIsEstimated,
+}: CompressionStatusTextOptions) {
+  if (isPending) {
+    return t('Compressing chat history');
+  }
+
+  const originalTokens = originalTokenCount ?? 0;
+  const newTokens = newTokenCount ?? 0;
+
+  switch (compressionStatus) {
+    case CompressionStatus.COMPRESSED:
+      return t(
+        'Chat history compressed from {{originalTokens}} to {{newTokens}} tokens.',
+        {
+          originalTokens: formatCompressionTokenCount(
+            originalTokens,
+            originalTokenCountIsEstimated,
+          ),
+          newTokens: formatCompressionTokenCount(
+            newTokens,
+            newTokenCountIsEstimated,
+          ),
+        },
+      );
+    case CompressionStatus.COMPRESSION_FAILED_INFLATED_TOKEN_COUNT:
+      // For smaller histories (< 50k tokens), compression overhead likely exceeds benefits.
+      if (originalTokens < 50000) {
+        return t('Compression was not beneficial for this history size.');
+      }
+      return t(
+        'Chat history compression did not reduce size. This may indicate issues with the compression prompt.',
+      );
+    case CompressionStatus.COMPRESSION_FAILED_TOKEN_COUNT_ERROR:
+      return t(
+        'Could not compress chat history due to a token counting error.',
+      );
+    case CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY:
+      return t(
+        'Could not compress chat history because the compression summary was empty.',
+      );
+    case CompressionStatus.COMPRESSION_FAILED_OUTPUT_TRUNCATED:
+      return t(
+        'Could not compress chat history because the compression summary was truncated.',
+      );
+    case CompressionStatus.COMPRESSION_FAILED_API_ERROR:
+      return t('Could not compress chat history due to an API error.');
+    case CompressionStatus.NOOP:
+      return 'Nothing to compress.';
+    default:
+      return '';
+  }
+}
+
+export function getCompressionFailureStatusText(
+  options: CompressionStatusTextOptions,
+) {
+  if (!isCompressionFailureStatus(options.compressionStatus)) {
+    return t('Failed to compress chat history.');
+  }
+
+  return (
+    getCompressionStatusText({
+      ...options,
+      isPending: false,
+    }) || t('Failed to compress chat history.')
+  );
+}
diff --git a/packages/core/src/core/llm-chat.test.ts b/packages/core/src/core/llm-chat.test.ts
index 8677e7df441..e7515ee03b3 100644
--- a/packages/core/src/core/llm-chat.test.ts
+++ b/packages/core/src/core/llm-chat.test.ts
@@ -4616,8 +4616,7 @@ describe('LlmChat', async () => {
         info: {
           originalTokenCount: 100_000,
           newTokenCount: 100_000,
-          compressionStatus:
-            CompressionStatus.COMPRESSION_FAILED_INFLATED_TOKEN_COUNT,
+          compressionStatus: CompressionStatus.COMPRESSION_FAILED_API_ERROR,
         },
       });
       vi.mocked(mockContentGenerator.generateContentStream).mockResolvedValue(
diff --git a/packages/core/src/core/llm-chat.ts b/packages/core/src/core/llm-chat.ts
index 9d0d349fe81..0b3ce157d11 100644
--- a/packages/core/src/core/llm-chat.ts
+++ b/packages/core/src/core/llm-chat.ts
@@ -105,7 +105,11 @@ import {
   makeChatCompressionEvent,
 } from '../telemetry/types.js';
 import type { UiTelemetryService } from '../telemetry/uiTelemetry.js';
-import { type ChatCompressionInfo, CompressionStatus } from './turn.js';
+import {
+  type ChatCompressionInfo,
+  CompressionStatus,
+  isCompressionFailureStatus,
+} from './turn.js';
 import { getContextLengthExceededInfo } from '../utils/contextLengthError.js';
 import {
   getStartupContextLength,
@@ -331,15 +335,6 @@ export function redactStructuredOutputArgsForRecording(
   };
 }
 
-function isCompressionFailureStatus(status: CompressionStatus): boolean {
-  return (
-    status === CompressionStatus.COMPRESSION_FAILED_INFLATED_TOKEN_COUNT ||
-    status === CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY ||
-    status === CompressionStatus.COMPRESSION_FAILED_TOKEN_COUNT_ERROR ||
-    status === CompressionStatus.COMPRESSION_FAILED_OUTPUT_TRUNCATED
-  );
-}
-
 function shouldStopAfterHardRescue(
   shouldForceFromHard: boolean,
   hardLimit: number,
diff --git a/packages/core/src/core/turn.test.ts b/packages/core/src/core/turn.test.ts
index 847bde64bad..98849de2012 100644
--- a/packages/core/src/core/turn.test.ts
+++ b/packages/core/src/core/turn.test.ts
@@ -12,6 +12,7 @@ import type {
 } from './turn.js';
 import {
   CompressionStatus,
+  isCompressionFailureStatus,
   Turn,
   LlmEventType,
   createDuplicateProviderToolCallResponse,
@@ -54,6 +55,49 @@ vi.mock('../utils/errorReporting', () => ({
   reportError: vi.fn(),
 }));
 
+describe('isCompressionFailureStatus', () => {
+  it('treats each compression failure status as failed', () => {
+    expect(
+      isCompressionFailureStatus(
+        CompressionStatus.COMPRESSION_FAILED_INFLATED_TOKEN_COUNT,
+      ),
+    ).toBe(true);
+    expect(
+      isCompressionFailureStatus(
+        CompressionStatus.COMPRESSION_FAILED_TOKEN_COUNT_ERROR,
+      ),
+    ).toBe(true);
+    expect(
+      isCompressionFailureStatus(
+        CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY,
+      ),
+    ).toBe(true);
+    expect(
+      isCompressionFailureStatus(
+        CompressionStatus.COMPRESSION_FAILED_OUTPUT_TRUNCATED,
+      ),
+    ).toBe(true);
+    expect(
+      isCompressionFailureStatus(
+        CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+      ),
+    ).toBe(true);
+  });
+
+  it('keeps API errors distinct from other compression failure statuses', () => {
+    expect(CompressionStatus.COMPRESSION_FAILED_API_ERROR).not.toBe(
+      CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY,
+    );
+    expect(CompressionStatus.COMPRESSION_FAILED_API_ERROR).not.toBe(
+      CompressionStatus.COMPRESSION_FAILED_TOKEN_COUNT_ERROR,
+    );
+    expect(isCompressionFailureStatus(CompressionStatus.COMPRESSED)).toBe(
+      false,
+    );
+    expect(isCompressionFailureStatus(CompressionStatus.NOOP)).toBe(false);
+  });
+});
+
 describe('findRepeatedDuplicateProviderToolCall', () => {
   const getProviderCallId = (item: { providerCallId?: string }) =>
     item.providerCallId;
diff --git a/packages/core/src/core/turn.ts b/packages/core/src/core/turn.ts
index c3a68e4d441..8b77c0cdddb 100644
--- a/packages/core/src/core/turn.ts
+++ b/packages/core/src/core/turn.ts
@@ -387,6 +387,25 @@ export enum CompressionStatus {
    * splitter). (R5.2)
    */
   COMPRESSION_FAILED_OUTPUT_TRUNCATED,
+
+  /**
+   * The compression side-query failed before producing a summary. Kept
+   * distinct from empty summaries so callers can tell API/provider failures
+   * apart from model output quality failures.
+   */
+  COMPRESSION_FAILED_API_ERROR,
+}
+
+export function isCompressionFailureStatus(
+  status: CompressionStatus | null | undefined,
+): boolean {
+  return (
+    status === CompressionStatus.COMPRESSION_FAILED_INFLATED_TOKEN_COUNT ||
+    status === CompressionStatus.COMPRESSION_FAILED_TOKEN_COUNT_ERROR ||
+    status === CompressionStatus.COMPRESSION_FAILED_EMPTY_SUMMARY ||
+    status === CompressionStatus.COMPRESSION_FAILED_OUTPUT_TRUNCATED ||
+    status === CompressionStatus.COMPRESSION_FAILED_API_ERROR
+  );
 }
 
 /**
diff --git a/packages/core/src/services/chatCompressionService.test.ts b/packages/core/src/services/chatCompressionService.test.ts
index 02aa39e9807..8d3108bb024 100644
--- a/packages/core/src/services/chatCompressionService.test.ts
+++ b/packages/core/src/services/chatCompressionService.test.ts
@@ -1910,6 +1910,100 @@ describe('ChatCompressionService', () => {
       expect(mockFirePostCompactEvent).not.toHaveBeenCalled();
     });
 
+    it('should return API error status when the compression side-query fails', async () => {
+      const history: Content[] = [
+        { role: 'user', parts: [{ text: 'msg1' }] },
+        { role: 'model', parts: [{ text: 'msg2' }] },
+        { role: 'user', parts: [{ text: 'msg3' }] },
+        { role: 'model', parts: [{ text: 'msg4' }] },
+      ];
+      vi.mocked(mockChat.getHistory).mockReturnValue(history);
+      vi.mocked(uiTelemetryService.getLastPromptTokenCount).mockReturnValue(
+        100,
+      );
+      vi.mocked(tokenLimit).mockReturnValue(1000);
+
+      const warn = vi.fn();
+      (
+        mockConfig as unknown as {
+          getDebugLogger: () => {
+            warn: typeof warn;
+            debug: ReturnType<typeof vi.fn>;
+          };
+        }
+      ).getDebugLogger = () => ({
+        warn,
+        debug: vi.fn(),
+      });
+      vi.spyOn(sideQueryModule, 'runSideQuery').mockRejectedValue(
+        new Error('context window exceeded'),
+      );
+
+      const result = await service.compress(mockChat, {
+        promptId: mockPromptId,
+        force: true,
+        config: mockConfig,
+        consecutiveFailures: 0,
+        originalTokenCount: uiTelemetryService.getLastPromptTokenCount(),
+      });
+
+      expect(result.info.compressionStatus).toBe(
+        CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+      );
+      expect(result.info.newTokenCount).toBe(100);
+      expect(result.newHistory).toBeNull();
+      expect(warn).toHaveBeenCalledWith(
+        expect.stringContaining('compression side-query failed'),
+      );
+      expect(mockFirePostCompactEvent).not.toHaveBeenCalled();
+    });
+
+    it('should rethrow aborts from the compression side-query', async () => {
+      const history: Content[] = [
+        { role: 'user', parts: [{ text: 'msg1' }] },
+        { role: 'model', parts: [{ text: 'msg2' }] },
+        { role: 'user', parts: [{ text: 'msg3' }] },
+        { role: 'model', parts: [{ text: 'msg4' }] },
+      ];
+      vi.mocked(mockChat.getHistory).mockReturnValue(history);
+      vi.mocked(uiTelemetryService.getLastPromptTokenCount).mockReturnValue(
+        100,
+      );
+      vi.mocked(tokenLimit).mockReturnValue(1000);
+
+      const warn = vi.fn();
+      (
+        mockConfig as unknown as {
+          getDebugLogger: () => {
+            warn: typeof warn;
+            debug: ReturnType<typeof vi.fn>;
+          };
+        }
+      ).getDebugLogger = () => ({
+        warn,
+        debug: vi.fn(),
+      });
+      const controller = new AbortController();
+      vi.spyOn(sideQueryModule, 'runSideQuery').mockImplementation(() => {
+        controller.abort();
+        return Promise.reject(new Error('cancelled'));
+      });
+
+      await expect(
+        service.compress(mockChat, {
+          promptId: mockPromptId,
+          force: true,
+          config: mockConfig,
+          consecutiveFailures: 0,
+          originalTokenCount: uiTelemetryService.getLastPromptTokenCount(),
+          signal: controller.signal,
+        }),
+      ).rejects.toThrow('cancelled');
+      expect(warn).not.toHaveBeenCalledWith(
+        expect.stringContaining('compression side-query failed'),
+      );
+    });
+
     it('should handle PostCompact hook errors gracefully', async () => {
       const history: Content[] = [
         { role: 'user', parts: [{ text: 'msg1' }] },
diff --git a/packages/core/src/services/chatCompressionService.ts b/packages/core/src/services/chatCompressionService.ts
index d27a9b667b1..12f991e634b 100644
--- a/packages/core/src/services/chatCompressionService.ts
+++ b/packages/core/src/services/chatCompressionService.ts
@@ -872,7 +872,24 @@ export class ChatCompressionService {
 
     if (!summaryResult) {
       abortSignal.throwIfAborted();
-      summaryResult = await runColdCompression();
+      try {
+        summaryResult = await runColdCompression();
+      } catch (error) {
+        if (abortSignal.aborted) throw error;
+        config
+          .getDebugLogger()
+          .warn(
+            `[chat-compression] compression side-query failed: ${String(error)}`,
+          );
+        return {
+          newHistory: null,
+          info: {
+            originalTokenCount,
+            newTokenCount: originalTokenCount,
+            compressionStatus: CompressionStatus.COMPRESSION_FAILED_API_ERROR,
+          },
+        };
+      }
     }
     const summary = summaryResult.text;
     // Check the PROCESSED summary: postProcessSummary strips <analysis>