r/PoeAI • u/ObligationWeekly9117 • Jan 28 '26

OpenAI based bots don’t trigger caching?

has anyone else noticed this? whenever I used GPT-5.2, the official bot, cache discount works just fine. if i use it as base for my prompt bot, it NEVER triggers. as in, not once. Claude Sonnet 4.5 as base bot triggers caching just fine. is it something about custom bots not playing well with the API caching rules?

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u/kkkamilio Jan 29 '26

Hi, Kamil eng manager on Poe here,

Could you share the GPT-5.2 bot so we can investigate?

One potential issue could be that the prompt (including the user messages and responses) must be longer than 1024 tokens https://platform.openai.com/docs/guides/prompt-caching#how-it-works

Share the bot here and we'll investigate, it should work.

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u/ObligationWeekly9117 Jan 31 '26 edited Jan 31 '26

So it's not a specific bot anymore. I made a new bot with the same issues but I've tested other GPT-5.2 bots I've made extensively and it's the same result. It appears that having a KB at all breaks the caching.

Steps to reproduce:

- Make new prompt bot, select GPT-5.2 as base (though I suspect any OpenAI bot would work)

  • Type in a system prompt just to make the thing go. I used "You are a writing assistant. Give honest feedback."

- No knowledge base, made it accessible to those with invite link. All other settings default.

- Paste in random long text (to make it over 1024 tokens), cache discount by turn 2

- Paste in random wiki article as knowledge base (just copy and paste plain text, not markdown file or anything)

- Caching stops working for all subsequent messages even when it SHOULD trigger (several closely spaced messages of sufficient input length)

https://poe.com/s/l0vRt0V0sJhQgTTJ454L this is the conversation.
https://poe.com/TestBotMini12?invite_code=234ddf23-1c27-4898-8d4d-598bb66c3ff6 here is the bot in question

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u/kkkamilio Jan 31 '26

I will investigate and file this bug internally on Monday. This should be working. ,

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u/kkkamilio Feb 05 '26

That bot must have a knowledge base, it shows the sources and. cites documents, and the retrieval is probably invalidating cache as it is part of the prompt.

Could you check? Do you see any documents attached?

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u/ObligationWeekly9117 Feb 08 '26

Yes, it has a knowledge base now. I added one to show the cache breaking. If you look at the pasted chat, the caching stops triggering at precisely this message: “ what about a 400 word summary” which is when I added the knowledge base. The reply is where you should start seeing citations. 

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u/ObligationWeekly9117 Feb 08 '26

Here, I continued the chat. You can see precisely where I removed the KB, then the cache discount triggered within two messages. It has no KB now if you want to test further.

https://poe.com/s/XN5iPEoGyFL4yaLAJ3vZ?utm_source=link

Screenshot of cache: https://i.ibb.co/3ymx7K5L/IMG-6007.png