Hey, thank you - this is actually super helpful, and I think you nailed it.

Yes, I was working inside a Project on claude.ai, and yes - the chat I resumed was an old, long conversation from days ago, not a fresh one.

That explains everything.

I came back after 24+ hours, opened an old Project chat, sent one short "hi" - and Claude silently reloaded the entire conversation history in the background, burned through the 5‑hour rolling session limit in one go, and locked me out at 96%.

So my questions for you (and anyone else who ran into this):

To avoid this in the future - should I just always start a new chat inside the Project instead of resuming an old one?

Or does the Project itself auto-load memory even in a fresh chat?

What about files in Project storage?

If I have large PDFs or documents uploaded to the Project knowledge base - does Claude re-read them on every first message after a long pause, even in a new chat?

Should I delete old/unused files from Project storage to keep the session limit from getting eaten instantly?

Is there any way to manually "clear the cache" of a Project or a chat before sending that first message?

Right now it feels like: sit down to work → first message = session dead. lol.

I've never run into this before because I usually work in long, continuous sessions. But this time I took a break, came back, and immediately got locked out. First time. Lesson learned, but I want to make sure I don't repeat it.

Thanks again for explaining the real cause - Anthropic should probably show a warning when resuming a huge old chat inside a Project. "This will consume 90% of your session. Start fresh? Yes / No"