Taproot Assets on Mainnet: Announcing tapd v0.3.0-alpha

Tapd v0.3.0-alpha, the first software release that supports the Taproot Asset Protocol on mainnet, has been announced. The release is deterministic and reproducible and can be found at this link: https://github.com/lightninglabs/taproot-assets/releases/tag/v0.3.0. A launch blog post detailing the release is available here: https://lightning.engineering/posts/2023-10-18-taproot-assets-v0.3/.For those interested in monitoring the usage and activity of the protocol, there are two Universes servers running. The mainnet server can be accessed at https://universe.lightning.finance/v1/taproot-assets/universe/roots and the testnet server at https://testnet.universe.lightning.finance/v1/taproot-assets/universe/roots. The REST API documentation for these servers can be found here: https://lightning.engineering/api-docs/api/taproot-assets/rest-endpoints. Additionally, users can interact directly via gRPC.Users also have the option to run their own Universe server and federate with other universe servers using the relevant tapcli universe federation command. The technical specification for the Universe/Multiverse protocol can be found in the BIP here: https://github.com/Roasbeef/bips/blob/bip-tap-pr/bip-tap-universe.mediawiki.At a high level, a Universe server is used by clients to verify new asset issuance, archive off-chain transaction data, and transmit proof information for transfers. The Universe data structure is an authenticated merkle-sum sparse merkle tree that maps an (outpoint, scriptKey) tuple to proof data. In the initial version of the protocol, the scriptKey is a taproot output public key. Bitcoin transactions are signed and verified as a logical state transition is mapped to a 1-in-1-out Bitcoin transaction.One interesting aspect of the protocol is the reuse of Bitcoin Script, allowing higher-level applications to use a familiar PSBT-like structure (vPSBTs) for constructing off-chain multi-party interactions. An example of using PSTBs, vPSBTs, and SIGHASH_NONE on the TAP layer to construct a protocol for non-interactive, non-custodial swaps can be found here: https://github.com/lightninglabs/taproot-assets/issues/577.Feedback and experimentation are encouraged for this mainnet alpha release to further evolve and improve the protocol. The release would not have been possible without the valuable feedback from those who experimented with earlier versions.