I think your effort paid off! The diagram for investigation is really interesting. I had some similar ideas about investigation games and how it doesn't fit a combat framework. Your clues-first direction was very close to what I imagined. A sense-driven system where you get information by paying points. I never played Gumshoe so I don't really see where it begins and ends. But it's still very good work!
Viewing post in ENIGMA: Investigation Rules comments
Actually the core of the Gumshoe system is that you get information by paying points. I intentionally removed point spending to try and simplify things. But, if I understand correctly, the creators of Gumshoe intended that point spending would limit investigation length.
The Gumshoe system is used as the basis for several different game settings you might find of interest (some of which might vaguely overlap with FIST themes), but you can download the setting-free Gumshoe SRD for free here:
https://pelgranepress.com/2013/10/24/the-gumshoe-system-reference-document/