This will mean that I can make it available to other developers to use in their own tools.
More hundreds of hours than I care to calculate have gone into developing the code which scans a website accurately and fully. It works well and I'm proud of that - parsing arbitrary (and sometimes non-compliant) html code is full of pitfalls.
For Scrutiny users, v6 will be a step forward, and may not be a paid upgrade. It will incorporate tools such as the .dot visualiser and the text-only engine (currently both available as SiteViz and Robotize)
For developers, I'd love to make the engine available. I feel that my strengths lie in building and maintaining that engine, more so than building a UI or producing and marketing a consumer product.
Work is underway. I'm not sure whether it'll be a cocoa framework (with friendly API), a CLI tool (which of course can be used in a Mac app) or both.
It won't be open source. I want to provide a free version and license a faster, paid-for version.
If you're interested then please let me know, it's shiela[at]peacockmedia.software. Work is now underway and it would be really useful to have an indication of interest and thoughts on how best to make the engine available.
[Update] The engine is now available in a demo xcode project which should give you the info you need to use it.