The manual says that unbesieged level 2 (or +) cities, all fortifications, depots and unblockaded harbors generate full SCs, in proportion to the structure level. However, it seems to me that only harbors seem to generate and supply ammunition. I've had ammunition wagons waiting indefinitely in Oxford and they never replenish ammunition, and neither do units who are low on ammunition, despite being a big city with depot and fortifications.
Is this by design, or do the files need editing? I had a look at the structures files and it is clear which structures supply ammunition and which don't. Opening the same files in TYW shows that cities and depots in that game do produce ammunition. Am I understanding this correctly, or am I missing something?