Add bsv namespace (BSV Blockchain)

[sirdeggen]

Summary

Adds a new namespace, bsv, for the BSV Blockchain, with a complete README.md and CAIP-2 profile. Registers four Chain IDs:

• bsv:mainnet — BSV main network
• bsv:testnet — BSV public test network
• bsv:ttn — Teranode Test Net (public Teranode scaling test network / Teratestnet)
• bsv:tstn — Teranode Scaling Test Net (private, per-deployment scaling test network)

Approach and rationale

BSV descends from the original Bitcoin protocol and shares Satoshi's genesis block with BTC and BCH. I want to be upfront that bip122 can represent BSV: it disambiguates forks by the first post-fork block hash (as it does for Bitcoin Cash, bip122:000000000000000000651ef99cb9fcbe), and a BSV entry could be built the same way from its fork block.

This namespace uses the human-readable network name as the CAIP-2 reference instead, following the casper precedent (a Chain ID that "should not be confused with the genesis_hash"). The reason is that the BSV application layer — BRC-100 wallets, overlay services, ARC broadcasters, SPV clients — universally identifies a network by name, never by fork-block hash. A BRC-100 wallet self-reports via getNetwork → mainnet/testnet (and ttn/tstn on Teranode deployments); SV Node's getblockchaininfo.chain returns main/test. Cross-chain tooling (e.g. the x402 payment protocol, CAIP-10/CAIP-19 references) can then map directly onto identifiers applications already exchange without a full-node round-trip. The two schemes can coexist — a hash-based bip122 BSV entry and this name-based one occupy different namespaces.

ttn and tstn are registered up front so high-throughput payment protocols can target Teranode test environments without overloading bsv:testnet or inventing ad-hoc names that later need client migration. Clients MUST NOT treat a genesis-only bip122 identifier as a BSV network — that reference is ambiguous across the BTC/BCH/BSV split.

Resolution mechanics, syntax (bsv:(mainnet|testnet|ttn|tstn)), and test cases are in bsv/caip2.md.

Context

This registration supports adding BSV as a payment mechanism to the x402 protocol, where the design discussion for these identifiers is ongoing. Happy to adjust the reference scheme (including moving to bip122) based on editor guidance.

Author: @sirdeggen (BSV Association).

[andyrowe]

I maintain a live implementation of the x402 exact scheme for BSV payments (bsv.cx), and this namespace gap is a concrete blocker for it.

Today the only CAIP-2 identifier available for BSV is bip122: — but that's ambiguous: BSV shares Satoshi's genesis block with BTC (and BCH), so a bip122: reference alone can't distinguish the three. My implementation currently works around this by pairing the bip122: network id with a non-standard extra.chain: "bsv" field plus asset: "BSV", and refusing to settle a payment whenever a Bitcoin-family network id arrives without that disambiguator. It works, but it's a workaround for a missing standard identifier.

Registering the bsv namespace here (bsv:mainnet / bsv:testnet) would let conforming implementations reference the chain unambiguously and drop the custom disambiguation. Is there anything currently blocking review, or something I could contribute to help it along — extra CAIP-2 profile detail, an implementer reference, test vectors? Happy to help however's useful.