سَيَجِيءُ زَيْدٌ رَاكِبًا
Zayd will come riding.
In this sentence rākiban is a grammatical ḥāl, yet the event it describes is future. The grammatical label “circumstantial accusative” does not automatically mean “happening at speech time.”
The distinction matters because hal’s prospective reading need not conflict with every occurrence of a circumstantial clause. The difficulty arises when the discourse explicitly targets an event as already occurring now.