fix: preserve changes when diff fails

tests/unit/pi-product-tools.test.ts

@@ -143,6 +143,40 @@ describe('PI-090 product tools', () => {
     )).files).toEqual([expect.objectContaining({ path: 'notes.txt', preview: 'local notes\n' })]);
   });
 
+  it('keeps the changed path when a candidate diff is unavailable or oversized', async () => {
+    const root = await temporaryRoot('makelore-pi-diff-unavailable-');
+    await writeFile(path.join(root, 'tracked.txt'), 'changed\n', 'utf8');
+    let statusReads = 0;
+    const tracker = new ConversationChangeTracker({
+      async run(_projectPath, args) {
+        if (args[0] === 'rev-parse' && args[1] === '--is-inside-work-tree') {
+          return { code: 0, stdout: 'true\n' };
+        }
+        if (args[0] === 'rev-parse') return { code: 0, stdout: `${'a'.repeat(40)}\n` };
+        if (args[0] === 'status') {
+          statusReads += 1;
+          return {
+            code: 0,
+            stdout: statusReads === 1
+              ? ''
+              : '1 .M N... 100644 100644 100644 abc abc tracked.txt\0',
+          };
+        }
+        if (args[0] === 'diff') throw new Error('Git output is too large');
+        throw new Error(`Unexpected Git call: ${args.join(' ')}`);
+      },
+    });
+    await tracker.beginRun({
+      conversationId: 'conversation-a', runId: 'run-a', projectPath: root,
+    });
+    const snapshot = await tracker.recordTouchedPaths(
+      'conversation-a', 'run-a', ['tracked.txt'],
+    );
+    expect(snapshot.files).toEqual([{
+      path: 'tracked.txt', status: 'modified',
+    }]);
+  });
+
   it('supports no-git projects and rejects paths outside the project', async () => {
     const root = await temporaryRoot('makelore-pi-no-git-');
     await writeFile(path.join(root, 'notes.txt'), 'local notes\n', 'utf8');