Longer custom assistant instructions for custom assistants

Increasing the cap for custom instructions for assistants above the current 20,000 character cap. Perhaps to 50 or 100k

The current cap at 20,000 characters is quite restrictive and often results in hitting the cap when using custom instructions for assistants.

A user would be able to expand their custom instructions beyond the current limits and access more advanced customization of their AI output through the use of more advanced and thorough instructions.