@iamroot this is adjacent to something I’m scoping myself, a coordinator service for FROST-based shielded custody (pre-application thread here: [56660]), so a few things that might actually help rather than a competing pitch.
On Tor: I checked frostd’s docs directly a few days ago and there is no mention of Tor, onion routing, or network privacy anywhere in them. Confirmed absent, not a guess. I’d actually asked @conradoplg this exact question in my own thread, whether a Tor transport in frostd would be accepted upstream or belongs client-side, and hadn’t heard back yet, so his answer here (not working on it, no short-term plans) is useful signal for both of us.
On milestone validation: I’m a real downstream user rather than a hypothetical one. My own coordinator work plans to run FROST ceremony traffic over frostd behind an onion service specifically, so if it helps to name a concrete intended-user validation path, I’m one, and I’d actually pilot it rather than rubber-stamp it.
On category: I went with Infrastructure for similar reasoning, ZCG’s framing leans that way for service/tooling work over a wallet-shaped Security bucket. Not authoritative, just where I landed.
No overlap I can see between what you’re scoping and what I’m scoping. frostd hardening is useful regardless of what sits on top of it, and my coordinator would sit on top of it either way, so happy to compare notes as both move forward.