fix(logs): keep newline between log pages in get_log_by_pointer (#2826)

Signed-off-by: ShryukGrandhi <[email protected]>

src/langbot/pkg/utils/logcache.py

@@ -57,12 +57,12 @@ class LogCache:
         start_offset: int,
     ) -> tuple[str, int, int]:
         """获取指定页码和偏移量的日志"""
-        final_logs_str = ''
+        final_logs: list[str] = []
 
         for page in self.log_pages:
             if page.number == start_page_number:
-                final_logs_str += '\n'.join(page.logs[start_offset:])
+                final_logs.extend(page.logs[start_offset:])
             elif page.number > start_page_number:
-                final_logs_str += '\n'.join(page.logs)
+                final_logs.extend(page.logs)
 
-        return final_logs_str, page.number, len(page.logs)
+        return '\n'.join(final_logs), page.number, len(page.logs)

tests/unit_tests/utils/test_logcache.py

@@ -159,6 +159,17 @@ class TestLogCache:
         assert 'page0 log 0' in result
         assert 'page1 log 0' in result
 
+    def test_get_log_by_pointer_across_pages_keeps_line_boundaries(self):
+        """Lines from adjacent pages are separated by a newline, not glued together."""
+        cache = LogCache()
+        logs = [f'log {i}' for i in range(LOG_PAGE_SIZE * 2 + 1)]
+        for log in logs:
+            cache.add_log(log)
+
+        result, _, _ = cache.get_log_by_pointer(0, 0)
+
+        assert result.split('\n') == logs
+
     def test_get_log_by_pointer_from_second_page(self):
         """get_log_by_pointer can start from second page."""
         cache = LogCache()