When setting multi-step generateText, promptMessages should be compressed or partially truncated

[lironghai]

Description

When setting multiple steps in generateText, promptMessages should be compressed or partially truncated to avoid maxtoken overflow caused by excessively long promptMessages.
Or should we extend a promptMessages processing function

AI SDK Version

• ai: 4.3.10

[lgrammel]

The AI SDK aims to give you full control over your prompts, and automatic compression would break this. You would currently need to do this yourself.