The idea is to easily visually show the current messages being considered in the Context Limit set in the Model & Parameter settings.

One idea would integrate with my idea of making the content area more "IDE-Like." (See one of my other posts today).

You could use a vertical color bar on the left side along with line numbers.

This could also integrate with a new auto-folding (enable/disable) feature for previous messages that fall outside the scope of the Context Limit.

You could also add a counter that shows how many messages are remaining before the Context Limit is full, similar to what you have for "About This Chat / Chat info" Icon (upper right content area) concerning the context length.