feat(core): report compression API failures distinctly

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();

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,

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
   // ============================================================================

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
   // ============================================================================

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
   // ============================================================================

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
   // ============================================================================

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.':

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
   // ============================================================================

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
   // ============================================================================

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.':

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
   // ============================================================================

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.