added concurrency limiting

src/monitor_utils/runner.py

@@ -293,7 +293,7 @@ async def execute_pagination(
     func: Callable[..., Awaitable[None]],
     session: aiohttp.ClientSession | AsyncSession,
     *,
-    max_concurrent_tasks: int = 5,
+    semaphore: asyncio.Semaphore,
     start_offset: int = 0,
     pagination_mode: str = "offset",
     **kwargs,
@@ -311,7 +311,11 @@ async def execute_pagination(
         func: Awaitable task invoked per page; receives session plus either
             offset or page_number depending on pagination_mode.
         session: HTTP session forwarded to each func call.
-        max_concurrent_tasks: Semaphore limit for concurrent page fetches.
+        max_concurrent_tasks: Semaphore limit for concurrent page fetches, used
+            only when semaphore is not supplied. Each execute_pagination call
+            builds its own semaphore, so this bounds one category in isolation;
+            with many categories running concurrently the effective limit is
+            this value times the category count.
         start_offset: Additive base applied to every offset, for APIs whose
             offset space does not begin at zero. Page N requests offset
             start_offset + (N - 1) * products_per_page.
@@ -327,7 +331,6 @@ async def execute_pagination(
         "executing pagination",
         extra={"category": category_identifier, "total": total_pages},
     )
-    semaphore = asyncio.Semaphore(max_concurrent_tasks)
     stop_event = asyncio.Event()
     pagination_label = "offset" if pagination_mode == "offset" else "page"
     page_range = range(2, total_pages + 1)