From: Jonathan Voss <k98kurz@gmail.com>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: [bitcoindev] Re: Draft BIP: DustSweep – policy-only UTXO dust compaction
Date: Fri, 12 Dec 2025 10:10:50 -0800 (PST) [thread overview]
Message-ID: <382cefe0-4ac0-43d7-919b-c56fad0a9b27n@googlegroups.com> (raw)
In-Reply-To: <b47aa182-bca7-44d7-bed1-f3cc2df30ef5n@googlegroups.com>
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Interesting proposal. Something like that would be helpful, but perhaps it
would be more useful if it was not quite so narrowly defined. For example,
instead of requiring all inputs be dust-class UTXO, it could require a
minimum of 80% dust-class inputs; instead of exactly one output, it could
be max_outputs = floor(n_inputs / 5) to keep a maximum output/input ratio
of 1/5. This could allow for better aggregation of dust outputs into
economically meaningful, monetary outputs than the narrower definition
while maintaining the incentives for meaningfully reducing UTXO set size.
I would run this policy on my node. Hashers should ultimately be okay with
this policy since someone among them also has to run full nodes, and it
would provide an additional (albeit very small) fee source when block space
demand is low.
On Thursday, December 11, 2025 at 8:34:16 AM UTC-5 defenwycke wrote:
> Hello list,
>
> I’ve been working on a small policy proposal that aims to address one very
> specific problem: the long-term accumulation of uneconomical dust in the
> UTXO set.
>
> The idea is intentionally narrow. I’m calling it DustSweep, and it defines
> a strict, non-abusable class of transactions that nodes may relay and
> miners may include only when the mempool and block space are underutilised.
> The goal is to give wallets a predictable way to compact dust without
> introducing new spam vectors or touching consensus.
>
> A DustSweep transaction has the following properties:
>
> -
>
> all inputs are “dust-class” UTXOs
> -
>
> only standard scripts (P2PKH / P2WPKH / P2TR)
> -
>
> exactly one output
> -
>
> no metadata at all (no OP_RETURN, inscriptions, TLVs, etc.)
> -
>
> minimum of 5 inputs (to ensure meaningful UTXO reduction)
> -
>
> size capped
> -
>
> it pays a flat 1 sat per input fee
>
> Nodes place these in a small, separate sub-mempool. They’re only accepted
> when the normal mempool is <50% full, and they’re automatically evicted if
> normal mempool usage hits 95%. Miners can include them up to a small weight
> fraction (I suggest ~5%) but only after filling the block with regular
> fee-paying transactions. The intention is that DustSweep never competes
> with the fee market and only uses blockspace that would otherwise go unused.
>
> This is all policy-level. No consensus changes, no new transaction format,
> nothing that affects validation. Nodes that don’t implement it simply treat
> these as low-fee transactions and drop them.
>
> The motivation is straightforward: we don’t currently have a safe,
> structured way to compact dust, and the UTXO set continues to grow from
> outputs that are effectively unspendable under normal fee conditions.
> DustSweep tries to offer a predictable, opt-in mechanism for wallets to
> clean that up without creating any new attack surface.
>
> Full draft BIP and supporting documents are here:
>
> https://github.com/defenwycke/bip-dust-sweep
>
> I’d appreciate feedback on the policy details, thresholds, and whether
> this fits within what node operators and wallet developers would actually
> want to use. Happy to adjust parameters if there’s a better balance point.
>
> Kind regards,
>
> Defenwycke
>
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next prev parent reply other threads:[~2025-12-12 18:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-11 12:53 [bitcoindev] " defenwycke
2025-12-12 18:10 ` Jonathan Voss [this message]
2025-12-12 20:17 ` [bitcoindev] " Defenwycke
2025-12-12 22:49 ` [bitcoindev] " Murch
2025-12-13 14:56 ` defenwycke
2025-12-22 19:06 ` Murch
2025-12-22 19:33 ` Defenwycke
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