Clarification: how should addr(SH_ADDRESS) be treated for dust?

[rodionmish]

Hi! I’m trying to understand the intended behavior.

In @bitcoinerlab/descriptors, the comment says that when a descriptor is addr(address) and the address is SH-type, it’s assumed to be Segwit sh(wpkh(...)) (nested).

https://github.com/bitcoinerlab/descriptors/blob/9b288e7719478c42fcb97bc36bc78f04a069878d/src/descriptors.ts#L1008

     * Whether this `Output` is Segwit.
     *
     * *NOTE:* When the descriptor in an input is `addr(address)`, it is assumed
     * that any `addr(SH_TYPE_ADDRESS)` is in fact a Segwit `SH_WPKH`
     * (Script Hash-Witness Public Key Hash).
     * For inputs using arbitrary scripts (not standard addresses),
     * use a descriptor in the format `sh(MINISCRIPT)`.
     *

In @bitcoinerlab/coinselect, dust.ts uses a fallback input weight of native P2WPKH = 272 wu (~67 vB) when the input weight is unknown for addr(TR|SH|WSH):

(

coinselect/src/dust.ts

Line 55 in 2e6a050

// When sending to scripts (such as TR, SH, or WSH) using an addr() descriptor,

)

For addr(SH_ADDRESS), should the default assumption be nested sh(wpkh) or native p2wpkh?
For compatibility with Bitcoin Core’s GetDustThreshold (which treats P2SH outputs as non-witness and adds a 148 vB P2PKH input), do you recommend matching Core, or sticking with your current fallback?

[landabaso]

I see your point. I'm not sure what the best approach is here... I like keeping things consistent with bitcoinerlab/descriptors assumptions, but matching Core's behaviour might indeed be the safer option.

If you'd like to open a PR we can discuss the details there. In the meantime, if you want to conform to Core, the simplest workaround would be to replace any addr(sh-...) with a generic addr(pkh-...) purely for the dust threshold computation. That way you'll be aligned with Core’s constants without changing the rest of the logic.

[rodionmish]

Thanks for the answer!
In this descriptors fork, we changed the handling of addr(SH_ADDRESS) to treat them as legacy P2SH-P2PKH (isSegwit = false) instead of assuming Segwit SH_WPKH. This aligns with Bitcoin Core's dust threshold calculations and ensures compatibility with Core's fee estimation behavior.