The Bitcoin development mailing list is in open warfare this week over a draft proposal nicknamed “The Cat,” which aims to make certain non-monetary UTXOs permanently unspendable. The controversy hit a boiling point when legendary developer Greg Maxwell denounced the idea as “confiscation and theft,” arguing it threatens Bitcoin’s core credibility. Maxwell even proposed a radical rule: ban any discussion of “confiscating Bitcoin” from the mailing list for a year, calling such debates “invalid” and damaging to the project’s reputation.

The proposal, authored by Claire Ostrom, targets what supporters describe as an unprecedented explosion in Bitcoin’s UTXO set driven by Ordinals and Stamps inscriptions. “The Cat” would use a soft fork to snapshot and permanently freeze non-monetary UTXOs below 1,000 satoshis, effectively removing them from the UTXO set and reducing its size by an estimated 30% to 50%. The draft BIP explicitly states it does not restrict new transactions; instead, it aims to “eliminate the financial incentives for creating NMUs in the first place”.

The Catalyst: A Mailing List Meltdown

The flashpoint is not the proposal itself, which has been circulating since late 2025, but the tone of the debate. In recent days, the Bitcoin-dev mailing list has seen heated exchanges between Ostrom’s supporters and opponents like Maxwell. Maxwell’s call to censor the discussion adds a layer of procedural drama, underscoring how deeply the issue divides the community.

A competing proposal, “Lynx,” offers a more neutral alternative: automatically invalidating dust UTXOs that remain untouched for four years, tied to the halving cycle. But “The Cat” remains the lightning rod. Critics claim it sets a dangerous precedent for confiscating coins based on external indexers and subjective definitions of “spam”.

Market data shows the stakes are real. Bitcoin Knots, a client that enforces stricter transaction rules, now accounts for roughly 18% of reachable nodes, reflecting a growing contingent that favors limiting non-financial data on-chain. Meanwhile, miners have profited over $500 million in the past year from Ordinals and Runes transactions, creating a powerful economic incentive to resist any cleanup.

The Technical and Philosophical Divide

The core of the fight is not about whether UTXO bloat is a problem. It’s about whether the solution is worth the cost. Between 2009 and early 2023, the UTXO database grew gradually to roughly 80-90 million entries. Within just one year, it doubled to over 160 million entries, with analyses suggesting nearly half of all UTXOs now contain less than 1,000 satoshis.

Supporters, like Bitcoin Mechanic, argue that the UTXO set is a resource that users must contribute to maintaining. “I don’t consider it unreasonable for Bitcoin users to do this if they see fit,” he wrote, emphasizing that between 40-50% of the UTXO set consists of spam outputs with dust amounts. Developer Nona YoBidnes added that the proposal would send a strong signal to discourage future spam: “Less spam is the objective here. I’m not concerned with the price of spam, only the quantity”.

Opponents, however, see a red line. In my experience, Bitcoin’s value proposition rests on a simple promise: if you control the private key, the coins are yours. “The Cat” would break that principle for the first time, creating a precedent where valid UTXOs can be invalidated for “system reasons”. Maxwell also argues the proposal won’t even work. “NFTs are just an imaginary parallel world that don’t depend on the network to validate their activity,” he wrote, warning that the soft fork would trigger a flood of evasion transactions while failing to stop NFT trading.

The Path Forward

The immediate catalyst is the upcoming Bitcoin Core v30 release, which will adjust OP_RETURN relay policies and likely intensify the debate over non-financial data. How the community responds to “The Cat” in the coming weeks will set the tone for Bitcoin’s governance for years. As Giacomo Zucco noted at Lugano Plan ₿ 2026, both camps claim the other will “kill Bitcoin”. The truth, as always, lies in the messy, contentious process of rough consensus.

Summary

“The Cat” is a draft proposal that would permanently freeze non-monetary UTXOs under 1,000 satoshis to combat UTXO bloat from Ordinals and Stamps. While supporters see it as a necessary technical cleanup, critics like Greg Maxwell label it “theft” and warn it threatens Bitcoin’s neutrality. The debate has turned personal on the Bitcoin-dev mailing list, with calls to censor discussion. A competing proposal, “Lynx,” offers a more automated alternative. Regardless of outcome, the controversy highlights Bitcoin’s ongoing struggle to balance scalability, property rights, and resistance to arbitrary data. The next few weeks, especially around the v30 release, will be decisive.