I start with a conversation and then ask the coding agent to write a design doc. It might go through several revisions. The implementation might also be a bit different if something unexpected is found, so afterwards I ask the agent to update it to explain what was implemented.

This naturally happens over several commits. I suppose I could squash them, but I haven't bothered.

I use the same approach, derived off of https://boristane.com/blog/how-i-use-claude-code/.