Free models trigger various restrictions and warnings of paid models

A few issues I've noticed with free models (like Owl Alpha at the time of writing this):

• Limits exhausted → cannot edit messages, have to branch off

• Limits exhausted → cannot regenerate responses using the button on a user message, have to branch off or use the button on a response message

• Free models show “Large message context may be expensive” warnings, both as a callout block and as a warning icon in the chat input