Building an SEO tool that plans the whole cluster, not just the keywords

I've been building a suite of AI marketing tools this year (23 shipped so far), and this one's been the most fun to design.

Most SEO tools stop at a keyword list and leave the strategy up to you. I wanted something that reasons through the full architecture the way I'd plan it for a client — pillar page, supporting clusters split by funnel stage, internal linking rules with exact anchor text, featured snippet targeting, and a day-by-day publishing calendar, all from one seed keyword.

Launching it on PH soon. Curious how other people here currently handle cluster planning — spreadsheet, Notion doc, dedicated tool? Trying to figure out what this is actually replacing for people.