Is it typical for the provider to have a supply of condoms available?  I have only done this once and I brought my own (since I honestly wasn't sure) and I didn't need it because the provider provided.  Is that the wayit usually works, or should I always plan to bring my own with me "just in case"?

but, bringing your own, as a back up plan,  is always a good idea. I've been  doing this for awhile and trust me, even well reviewed ladies run out or forget every once in a blue moon.

Unless there is possible problem you may have with standard ones (such as latex allergies, size difficulties, or if you prefer something like desensitizing lube). Ask them about it if your concerned, given enough time they may opt to have what you prefer ready for your visit.

Generally yes.  However there are certain times...  and even a few scams...  when it's handy to have your own.  A sealed 3 pack is good.  I respect a lady's right to use her own though I've never been denied to use my premium brand.  I place them on the table & then excuse myself to the bathroom so she has an opportunity to inspect them.  I leave any excess.
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It's like a hair dresser forgetting his or her scissors... Where did she think she was going that day...

If you have a favorite brand bring an unopened box (if it's with me even bring the recent receipt). I know it sounds freaky but I'm always afraid someone has left them in their car, pockets, too long or over heat or freezing weather. We take enough chances as is why take more?

Someone brought lamb skin once... get this he was an MD... Another MD has asked for bareback too last year. Things you hear... makes you want to have a delete button in your brain.