txmanifest

txmanifest is a JSON-based file format for describing Simplicity contracts. It provides a reusable, standardized way to teach wallets how to describe and interact with a Simplicity contract on-chain. This reduces the need to build custom UI and transaction logic for each contract/wallet pair.

When a wallet application imports a trusted manifest file describing a contract, the wallet application learns how to recognize instances of the described contract on the blockchain, how to describe those details to a user, and how to build new transactions that perform actions in that contract instance.

For smart contract developers, txmanifest provides a way to describe a contract once and achieve interoperability with a whole ecosystem of wallets.

For wallet developers, txmanifest provides a way to add UI and transaction functionality once and achieve interoperability with a whole ecosystem of smart contracts.

Online documentation

The txmanifest format is work-in-progress and has not yet been frozen as a released specification. Detailed documentation for the txmanifest format is available in the txmanifest book.

Reference implementation

The txmanifest-wallet project provides a reference implementation of txmanifest as a developer-oriented wallet application with a textual user interface.

You can use txmanifest-wallet to debug and experiment with manifest files describing new or existing Simplicity contracts. An interactive online demonstration of this tool, with sample manifests and contracts, is available in the txw codespace.

Security considerations

The txmanifest format does not include a means to confirm or verify the correctness of descriptions.

Trusting an inaccurate or deceptive manifest file can result in wallets misinterpreting the meaning or effect of transactions, and misdescribing them to users. This could cause users' assets to be lost or stolen because the users approve transactions with undesired or unintended effects, including transferring assets to an attacker's control.

For example, a manifest file could falsely state that transferring currency to a certain address deposits it as collateral for a loan, which can purportedly be reclaimed by repaying the loan. In reality, the loan could have highly unfavorable terms that the wallet application fails to explain correctly, or the destination address could be some other form of contract that forfeits the user's deposit to an attacker with no further recourse.

Users and wallets must only import manifest files from appropriately trusted sources, and not automatically accept manifest files posted online or sent to them by strangers.