Add NEAR Protocol namespace (near) with CAIP-2 profile

[okwme]

Adds a CAN for NEAR Protocol with a CAIP-2 Blockchain ID profile.

This answers the open request in #106 ("CAIP-2 for NEAR"), which pointed at ChainAgnostic/CAIPs#43 — that PR was closed unmerged in 2023 with "please make all namespace PRs in the namespaces repo", and nobody did. There is no near/ folder and no other NEAR PR, so this should not collide with in-flight work.

Who wrote this, and why you should read it sceptically

I do not represent the NEAR ecosystem. I maintain FAR, an open cross-reference between CAIP-19, CoinGecko and ISO 24165 (DTI) identifiers, which needs a CAIP-2 for NEAR in order to name 72 assets that exist on it. This is offered as a starting point for NEAR's maintainers to correct, adopt or replace, and I would rather it carried their name than mine. Happy to close it in favour of a NEAR-authored version.

Proposal

near: + the nearcore chain_id string, verbatim and case-sensitive.

near:mainnet
near:testnet

Verified live (2026-09-14)

• status on rpc.mainnet.near.org and rpc.testnet.near.org, and independently on free.rpc.fastnear.com / test.rpc.fastnear.com — all four agree chain_id is literally "mainnet" / "testnet".
• RpcStatusResponse.chain_id is a required field in nearcore's own OpenAPI, documented "Unique chain id", with the warning "If your testnet blockchains do not have unique chain IDs, you will have a bad time".
• Network constants read from core/primitives-core/src/chains.rs.

Why the human-readable id rather than a genesis hash

Two reasons the spec argues rather than asserts:

1. NEAR has no block 0. Both public endpoints return UNKNOWN_BLOCK for block 0 — genesis heights are 9,820,210 (mainnet) and 42,376,888 (testnet), because each network's genesis is a state snapshot rather than a bootstrapped empty chain. An implementer following the usual "query block 0" recipe gets an error.
2. The genesis hash is 44 base58 characters, over CAIP-2's 32-char limit, and base58 truncation lands on no byte boundary — the truncated value would be neither the hash nor a hash of anything. bip122's 32 hex chars are exactly the first 16 bytes; base58 has no such property.

Precedent cited: cosmos (cosmos:cosmoshub-3 appears in CAIP-2's own test cases), sui, flow, stellar, tezos.

Flagged for whoever writes the CAIP-19 profile

NEAR account ids may contain _ (verified live: v3.oin_finance.near is a working NEP-141 token), and _ is not legal in either a CAIP-19 asset_reference or a CAIP-10 account_address. Percent-encoding as %5F is legal under both and is named as the obvious candidate, but I deliberately left that decision to whoever writes those profiles rather than pre-empting it from outside the ecosystem.

discussions-to points at 0xcounting/FAR#1, which also carries the wider gap list.