Yes, I paste stuff in from larger projects all the time.
I'm very selective about what I give them. For example, if I'm working on a Django project I'll paste in just the Django ORM models for the part of the codebase I'm working on - that's enough for it to spit out forms and views and templates, it doesn't need to know about other parts of the codebase.
Another trick I sometimes use is Claude Projects, which allow you to paste up to 200,000 tokens into persistent context for a model. That's enough to fit a LOT of code, so I've occasionally dumped my entire codebase (using my https://github.com/simonw/files-to-prompt/ tool) in there, or selected pieces that are important like the model and URL definitions.
I'm very selective about what I give them. For example, if I'm working on a Django project I'll paste in just the Django ORM models for the part of the codebase I'm working on - that's enough for it to spit out forms and views and templates, it doesn't need to know about other parts of the codebase.
Another trick I sometimes use is Claude Projects, which allow you to paste up to 200,000 tokens into persistent context for a model. That's enough to fit a LOT of code, so I've occasionally dumped my entire codebase (using my https://github.com/simonw/files-to-prompt/ tool) in there, or selected pieces that are important like the model and URL definitions.