Opencode Prewalk is an Opencode v2 plugin that allows you to use the prewalk strategy mentioned here from the creators of Oh-My-Pi. The simple idea behind this strategy is to inject a cheaper model right after the expensive model finishes the first edit post planning all the things that needs to be done. This strategy is better the one strategy that directly uses combination of expensive and cheap model to get the work done, as what happens in that case is the cheaper model again starts to do a lot of reading leading of increase in token usage.
https://vivek.ink/p/opencode-prewalk