MATT Advances Bitcoin Covenants, but Mainnet Activation Remains Distant

By Marcus Bennett

As of late 2026, no covenant proposal, including BIP 443, has activated on Bitcoin mainnet.

Cointelegraph Research published Part 5 of its Bitcoin covenants series on November 11, 2026. The report examines MATT, short for Merkleize All The Things, and OP_CHECKCONTRACTVERIFY, or OP_CCV, the proposed opcode defined in BIP 443.

How would stateful Bitcoin contracts work?

Bitcoin Script normally evaluates each transaction in isolation. It keeps no built-in record of earlier contract state or required next steps.

MATT seeks to change that model. Cointelegraph Research summarized the aim: “Let Bitcoin outputs carry contract state forward, and let the network check that the state changed by the rules.”

The framework embeds contract-state data directly inside Taproot output keys through cryptographic tweaks. The state rides along inside the key itself.

OP_CCV serves as the validation gate during a spend. The opcode lets a script read state data supplied on the witness stack and run computations on it.

MATT then requires the resulting updated state to be committed again in a designated output. If that output does not carry the correct state, the spend fails.

This mechanism would enforce state transitions on-chain. Standard Bitcoin Script cannot do so because it evaluates every transaction without persistent contract memory.

What could MATT enable?

The research identifies four application groups: vaults, payment pools, transferable DLCs, or discreet log contracts, and optimistic smart contracts. Each depends on enforceable state rather than isolated transaction checks.

MATT also aims to improve fraud proofs, particularly when paired with OP_CAT. That separate proposed opcode supports Merkle proof verification.

In an optimistic system, participants treat a computation as correct unless someone proves otherwise. Combined with OP_CAT, MATT could facilitate on-chain Merkle proofs and fraud proofs supporting arbitrary computations.

Node operators shape the design constraints. The proposal aims to offer limited state and introspection without adding significant computational overhead to Bitcoin base-layer nodes.

That goal could determine whether developers accept a covenant framework that promises more functionality without burdening the nodes that validate every transaction.

How did MATT reach signet testing?

Salvatore Ingala first introduced MATT in November 2022 on the bitcoin-dev mailing list. He later presented the idea at BTCAzores.

BIP 443, which defines OP_CCV, gained BIP status in May 2025. Around that shift, OP_VAULT, specified in BIP 345, was withdrawn in favor of the MATT-based approach.

MATT has now been assigned the identifier BIN-2026-0002 for testing on a signet. Bitcoin’s signet is a test network where developers can try features without touching real money.

The identifier creates a testing path, not an activation date. Cointelegraph Research reported that no covenant proposal had reached Bitcoin mainnet by late 2026.

What does this change for Bitcoin builders?

It expands the design space for stateful contracts, but builders still have no deployed MATT functionality to use. The research also says the technical discussion carries no immediate price implications.

Cointelegraph Research wrote: “The bigger obstacle is social, not technical.” Consensus among Bitcoin developers remains the crucial barrier to moving covenant proposals toward implementation.

Several of MATT’s most ambitious use cases also depend on OP_CAT. Progress on that separate opcode would matter as much as MATT’s own signet results for fraud proofs and arbitrary computation.

The practical checkpoints are concrete: signet testing under BIN-2026-0002, whether developer discussion converges or fractures, and a credible route to activation. The research report was edited by Vivian Nguyen.

Without consensus and an activation path, BIP 443 will remain a proposal rather than mainnet functionality.