diff --git a/src/cli/actions/defaultAction.ts b/src/cli/actions/defaultAction.ts
index 57d55299..40958563 100644
--- a/src/cli/actions/defaultAction.ts
+++ b/src/cli/actions/defaultAction.ts
@@ -118,9 +118,13 @@ export const runDefaultAction = async (
     const handleProgress: RepomixProgressCallback = (message) => {
       spinner.update(message);
       if (progressCallback) {
-        Promise.resolve(progressCallback(message)).catch((error) => {
+        try {
+          Promise.resolve(progressCallback(message)).catch((error) => {
+            logger.trace('progressCallback error:', error);
+          });
+        } catch (error) {
           logger.trace('progressCallback error:', error);
-        });
+        }
       }
     };
 
diff --git a/tests/cli/actions/defaultAction.test.ts b/tests/cli/actions/defaultAction.test.ts
index 920e9463..748993e3 100644
--- a/tests/cli/actions/defaultAction.test.ts
+++ b/tests/cli/actions/defaultAction.test.ts
@@ -6,6 +6,7 @@ import * as configLoader from '../../../src/config/configLoad.js';
 import * as fileStdin from '../../../src/core/file/fileStdin.js';
 import * as packageJsonParser from '../../../src/core/file/packageJsonParse.js';
 import * as packager from '../../../src/core/packager.js';
+import * as loggerModule from '../../../src/shared/logger.js';
 import { createMockConfig } from '../../testing/testUtils.js';
 
 vi.mock('../../../src/core/packager');
@@ -156,6 +157,95 @@ describe('defaultAction', () => {
     expect(mockSpinner.fail).toHaveBeenCalledWith('Error during packing');
   });
 
+  describe('progressCallback', () => {
+    it('should forward progress messages to the provided callback', async () => {
+      // Configure pack mock to invoke its 3rd argument (progressCallback)
+      vi.mocked(packager.pack).mockImplementation(async (_paths, _config, progressCallback = () => {}) => {
+        progressCallback('Searching for files...');
+        progressCallback('Processing files...');
+        return {
+          totalFiles: 10,
+          totalCharacters: 1000,
+          totalTokens: 200,
+          fileCharCounts: {},
+          fileTokenCounts: {},
+          suspiciousFilesResults: [],
+          suspiciousGitDiffResults: [],
+          suspiciousGitLogResults: [],
+          processedFiles: [],
+          safeFilePaths: [],
+          gitDiffTokenCount: 0,
+          gitLogTokenCount: 0,
+          skippedFiles: [],
+        };
+      });
+
+      const callback = vi.fn();
+      await runDefaultAction(['.'], process.cwd(), {}, callback);
+
+      expect(callback).toHaveBeenCalledWith('Searching for files...');
+      expect(callback).toHaveBeenCalledWith('Processing files...');
+    });
+
+    it('should isolate async callback errors without affecting pack flow', async () => {
+      vi.mocked(packager.pack).mockImplementation(async (_paths, _config, progressCallback = () => {}) => {
+        progressCallback('test message');
+        // Allow microtask to process the rejected promise
+        await new Promise((resolve) => setTimeout(resolve, 10));
+        return {
+          totalFiles: 10,
+          totalCharacters: 1000,
+          totalTokens: 200,
+          fileCharCounts: {},
+          fileTokenCounts: {},
+          suspiciousFilesResults: [],
+          suspiciousGitDiffResults: [],
+          suspiciousGitLogResults: [],
+          processedFiles: [],
+          safeFilePaths: [],
+          gitDiffTokenCount: 0,
+          gitLogTokenCount: 0,
+          skippedFiles: [],
+        };
+      });
+
+      const rejectingCallback = vi.fn().mockRejectedValue(new Error('callback error'));
+      const result = await runDefaultAction(['.'], process.cwd(), {}, rejectingCallback);
+
+      expect(result.packResult.totalFiles).toBe(10);
+      expect(loggerModule.logger.trace).toHaveBeenCalledWith('progressCallback error:', expect.any(Error));
+    });
+
+    it('should still update spinner even when callback throws synchronously', async () => {
+      vi.mocked(packager.pack).mockImplementation(async (_paths, _config, progressCallback = () => {}) => {
+        progressCallback('test message');
+        return {
+          totalFiles: 10,
+          totalCharacters: 1000,
+          totalTokens: 200,
+          fileCharCounts: {},
+          fileTokenCounts: {},
+          suspiciousFilesResults: [],
+          suspiciousGitDiffResults: [],
+          suspiciousGitLogResults: [],
+          processedFiles: [],
+          safeFilePaths: [],
+          gitDiffTokenCount: 0,
+          gitLogTokenCount: 0,
+          skippedFiles: [],
+        };
+      });
+
+      const throwingCallback = vi.fn().mockImplementation(() => {
+        throw new Error('sync error');
+      });
+      await runDefaultAction(['.'], process.cwd(), {}, throwingCallback);
+
+      // Spinner should still be updated despite callback failure
+      expect(mockSpinner.update).toHaveBeenCalledWith('test message');
+    });
+  });
+
   describe('buildCliConfig', () => {
     it('should handle custom include patterns', () => {
       const options = {