update docs for review comment

Author: carderne

docs/management/runs/bulk-actions.mdx

@@ -30,6 +30,10 @@ console.log(completed.status, completed.counts);
 
 `filter` accepts the same filters as [`runs.list()`](/management/runs/list), excluding pagination fields. Provide at least one filter field; use `runIds` when you want to target specific runs. Relative time filters such as `period` are resolved when the bulk action is created, so later batches process the same fixed time range.
 
+<Warning>
+  Filters inherit the same time semantics as `runs.list()`: when you don't pass `from`, `to`, or `period`, the action defaults to the **last 7 days** and won't target older matching runs. To cover a wider range, pass an explicit `period` (such as `"30d"`), a `from` timestamp, or a `from`/`to` pair. This default only applies to `filter` selections; `runIds` selections are never time-bounded.
+</Warning>
+
 <Note>
   Each environment can only run a limited number of bulk replays at the same time. If you start a replay while too many are still in progress, the call fails and returns an error. Wait for an in-progress replay to finish (or [abort](#abort-a-bulk-action) one) before starting another. Bulk cancels are not subject to this limit.
 </Note>