diff --git a/src/monitor_utils/database.py b/src/monitor_utils/database.py
index 4f8ca5f..16c6cec 100644
--- a/src/monitor_utils/database.py
+++ b/src/monitor_utils/database.py
@@ -217,7 +217,11 @@ def resolve_price_before_drop(
         previous_price on a drop, otherwise None.
     """
 
-    if previous_price is not None and new_price is not None and new_price < previous_price:
+    if (
+        previous_price is not None
+        and new_price is not None
+        and new_price < previous_price
+    ):
         return previous_price
 
     return None
diff --git a/src/monitor_utils/runner.py b/src/monitor_utils/runner.py
index d28412b..685db12 100644
--- a/src/monitor_utils/runner.py
+++ b/src/monitor_utils/runner.py
@@ -191,15 +191,15 @@ async def execute_monitor_logic(
     proxies: AioProxies,
     headers: dict | None = None,
     cookies: dict | None = None,
-    pre_task_func: Callable[..., Awaitable[None]] | None = None,
+    concurrent_pre_task: Callable[..., Awaitable[None]] | None = None,
     use_tls: bool = False,
     **kwargs,
 ):
     """Run the monitor's category tasks in a loop with a fresh session per cycle.
 
-    Each cycle opens a TLS or base session, optionally runs pre_task_func,
-    dispatches task_func per category concurrently, logs expected failures,
-    raises unexpected ones, then sleeps briefly before the next cycle.
+    Each cycle opens a TLS or base session, dispatches task_func per category
+    concurrently, logs expected failures, raises unexpected ones, then sleeps
+    briefly before the next cycle.
 
     Args:
         category_identifiers: List of category ids, or a mapping of category
@@ -210,10 +210,13 @@ async def execute_monitor_logic(
         proxies: Proxies applied to the session.
         headers: Headers applied to the session.
         cookies: Cookies applied to the base session; ignored for TLS.
-        pre_task_func: Optional awaitable run once per cycle before category
-            tasks, receiving session and **kwargs.
+        concurrent_pre_task: Optional awaitable run once per cycle, gathered
+            alongside the category tasks and receiving session and **kwargs.
+            Category tasks must not depend on its side effects (session
+            headers, cookies, fetched state) since no ordering is guaranteed.
         use_tls: Use the TLS fingerprint session instead of the base session.
-        **kwargs: Forwarded verbatim to pre_task_func and every task_func call.
+        **kwargs: Forwarded verbatim to concurrent_pre_task and every
+            task_func call.
     """
 
     while True:
@@ -227,15 +230,6 @@ async def execute_monitor_logic(
         )
         async with session_ctx as session:
             LOGGER.info("starting tasks")
-            if pre_task_func:
-                try:
-                    await pre_task_func(session=session, **kwargs)
-                except EXPECTED_TASK_ERRORS as exc:
-                    LOGGER.warning("failed to get products", exc_info=exc)
-                except Exception:
-                    LOGGER.exception("unexpected error")
-                    raise
-
             if isinstance(category_identifiers, dict):
                 tasks = [
                     task_func(category_id, session, query_category_id=query, **kwargs)
@@ -247,7 +241,11 @@ async def execute_monitor_logic(
                     task_func(category_identifier, session, **kwargs)
                     for category_identifier in category_identifiers
                 ]
-                category_keys = category_identifiers
+                category_keys = list(category_identifiers)
+
+            if concurrent_pre_task:
+                tasks.append(concurrent_pre_task(session=session, **kwargs))
+                category_keys.append("pre_task")
 
             results = await asyncio.gather(*tasks, return_exceptions=True)
             for category_identifier, result in zip(category_keys, results):
diff --git a/src/monitor_utils/sessions.py b/src/monitor_utils/sessions.py
index 43a0689..b2e3181 100644
--- a/src/monitor_utils/sessions.py
+++ b/src/monitor_utils/sessions.py
@@ -146,6 +146,7 @@ async def send_request(
     params: dict | None = None,
     json_data: dict | None = None,
     data: dict | None = None,
+    headers: dict | None = None,
     reraise_json_error: bool = False,
     development_proxy: str | None = None,
 ) -> dict | str:
@@ -164,6 +165,8 @@ async def send_request(
         params: Query parameters.
         json_data: JSON body.
         data: Form body.
+        headers: Per-request headers merged over the session headers,
+            avoiding mutation of shared session state from concurrent tasks.
         reraise_json_error: Raise JSONDecodeError instead of returning raw
             text when the response is not valid JSON.
         development_proxy: Local proxy URL that overrides the pool and
@@ -193,6 +196,7 @@ async def send_request(
             params=params,
             json=json_data,
             data=data,
+            headers=headers,
             proxy=proxy,
             ssl=verify,
         ) as response:
@@ -205,6 +209,7 @@ async def send_request(
             params=params,
             json=json_data,
             data=data,
+            headers=headers,
             proxy=proxy,
             verify=verify,
         )