- Document libunbound's context lifetime during an async callback.

Thanks to Omar Mousa for the suggestion.

doc/Changelog

@@ -1,3 +1,7 @@
+2 October 2026: Yorgos
+	- Document libunbound's context lifetime during an async callback.
+	  Thanks to Omar Mousa for the suggestion.
+
 28 September 2026: Wouter
 	- Fix to log the errno for trust anchor write close fail.
 	- Merge #1518 from nshopik: rrset: rehash copies after

doc/libunbound.3.in

@@ -331,6 +331,8 @@ void my_callback_function(void* my_arg, int err,
 The \fBasync_id\fP is returned so you can (at your option) decide to
 track it and cancel the request if needed.
 If you pass a NULL pointer the \fBasync_id\fP is not returned.
+The context, created via \fBub_ctx_create\fP, is in use during but also
+after the callback and it cannot be deleted during a callback.
 .TP
 .B ub_cancel
 Cancel an async query in progress.

doc/libunbound.rst

@@ -408,6 +408,8 @@ Functions
         The **async_id** is returned so you can (at your option) decide to
         track it and cancel the request if needed.
         If you pass a NULL pointer the **async_id** is not returned.
+        The context, created via **ub_ctx_create**, is in use during but also
+        after the callback and it cannot be deleted during a callback.
 
     ub_cancel
         Cancel an async query in progress.