Can we remove Option here, and keep it just AllocatedExtranoncePrefix, and then pass it to new methods as owned, instead of having an Arc?

hmm I guess you want to bring the ownership pattern from stratum-mining/stratum#2098 into here (de-allocate automatically by dropping)

the main thing to keep in mind here is that UniFFI objects always cross the language boundary as handles/pointers, so they do not model move-only Rust ownership directly

I get how the Option seems a bit awkward at first, but we need a one-shot consume step on the Rust side, which is why the wrapper stores Option<AllocatedExtranoncePrefix> and uses take_inner() to consume it exactly once.

if this were a pure-Rust API, passing AllocatedExtranoncePrefix by value would make sense, but with the current UniFFI object boundary that would require a broader API redesign (e.g.: Sv2ExtranonceAllocator instantiating channels, which tbh feels like a terrible idea).

I'm adding comments to explain the reasoning behind Option, but I would prefer that we avoid broader API redesigns.

Very interesting that CI didn't flagged this

fixed and added 9801d35 to run some examples on CI

full example coverage on CI is non-trivial and out of scope