Thanks, I'll keep digging. You've already helped just by suggesting better search terms (e.g. “mind-mapping software").
That said, I’d still be surprised if someone hasn’t already built something close to this.
Slight tangent: About 15 years ago, I had what I thought was a novel app idea: an audio recorder that constantly buffers the last 60 seconds of sound, so if someone said something important, you could hit a button and retroactively capture it. I looked it up, and sure enough, it existed: fully developed but mostly abandoned. Same thing happened when I imagined vending machines at public tennis courts that dispense fresh tennis balls. Already patented, blueprint and all. I decided we'd reached the IP singularity (15 years ago!): naming is almost equivalent to invoking.
So unless my idea is downright incoherent or useless, I have to assume it’s already out there somewhere buried under the right search terms.
Adele, that's awesome. I'll definitely use it next time I need Bayes-level precision.
I've been working on this quite a bit. It's only Bayes-lite though: it blends beliefs using weighted averages in log-odds space and outputs the robustness and probability of the recalculated beliefs. That should be fine for my purposes and for layman use.
I've got the rawest of functional prototypes. But the hard part is done - the math checks out. It even propagates complex loops without breaking. It will take me a while to develop the UI though. Here's a screen grab. Not too pretty yet. I'll let you know when I really have something worth sharing.