diff --git a/packages/core/src/tools/diffOptions.test.ts b/packages/core/src/tools/diffOptions.test.ts
index cf6fe89b23..3df300181c 100644
--- a/packages/core/src/tools/diffOptions.test.ts
+++ b/packages/core/src/tools/diffOptions.test.ts
@@ -162,4 +162,21 @@ describe('getDiffStat', () => {
       user_removed_chars: 0,
     });
   });
+  it('should correctly report whitespace-only changes', () => {
+    const fileName = 'test.py';
+    const oldStr = 'def hello():\n print("world")';
+    const aiStr = 'def hello():\n    print("world")';
+    const userStr = aiStr;
+    const diffStat = getDiffStat(fileName, oldStr, aiStr, userStr);
+    expect(diffStat).toEqual({
+      model_added_lines: 1,
+      model_removed_lines: 1,
+      model_added_chars: 18,
+      model_removed_chars: 15,
+      user_added_lines: 0,
+      user_removed_lines: 0,
+      user_added_chars: 0,
+      user_removed_chars: 0,
+    });
+  });
 });
diff --git a/packages/core/src/tools/diffOptions.ts b/packages/core/src/tools/diffOptions.ts
index ad0738ba04..9bd6eab793 100644
--- a/packages/core/src/tools/diffOptions.ts
+++ b/packages/core/src/tools/diffOptions.ts
@@ -9,7 +9,7 @@ import type { DiffStat } from './tools.js';
 
 export const DEFAULT_DIFF_OPTIONS: Diff.PatchOptions = {
   context: 3,
-  ignoreWhitespace: true,
+  ignoreWhitespace: false,
 };
 
 export function getDiffStat(
diff --git a/packages/core/src/tools/modifiable-tool.test.ts b/packages/core/src/tools/modifiable-tool.test.ts
index 3cecccf554..4f34b20b57 100644
--- a/packages/core/src/tools/modifiable-tool.test.ts
+++ b/packages/core/src/tools/modifiable-tool.test.ts
@@ -136,7 +136,7 @@ describe('modifyWithEditor', () => {
         'Proposed',
         expect.objectContaining({
           context: 3,
-          ignoreWhitespace: true,
+          ignoreWhitespace: false,
         }),
       );
 
@@ -205,7 +205,7 @@ describe('modifyWithEditor', () => {
       'Proposed',
       expect.objectContaining({
         context: 3,
-        ignoreWhitespace: true,
+        ignoreWhitespace: false,
       }),
     );
 
@@ -233,7 +233,7 @@ describe('modifyWithEditor', () => {
       'Proposed',
       expect.objectContaining({
         context: 3,
-        ignoreWhitespace: true,
+        ignoreWhitespace: false,
       }),
     );