docs: add Avalanche CAIP-2 (#1)

avalanche/README.md

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+---
+namespace-identifier: avax
+title: Avalanche Ecosystem
+author: Gergely Lovas (@gergelylovas)
+discussions-to: []
+status: Draft
+type: Informational
+created: 2024-07-16
+replaces: CAIP-28
+---
+
+# Namespace for Avalanche chains
+
+This document defines the applicability of CAIP schemes to the blockchains of
+the Avalanche Ecosystem.
+
+## Syntax
+
+The namespace `avax` refers to the Avalanche Ecosystem, including private
+Avalanche L1s.
+
+## References
+
+[Official website]: https://www.avax.network/
+[Avalanche documentation]: https://docs.avax.network/
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).

avalanche/caip2.md

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+---
+namespace-identifier: avax-caip2
+title: Avalanche Namespace - Chains
+author: Gergely Lovas (@gergelylovas)
+discussions-to: []
+status: Draft
+type: Standard
+created: 2024-07-16
+requires: CAIP-2
+---
+
+# CAIP-2
+
+*For context, see the [CAIP-2][] specification.*
+
+## Rationale
+
+In CAIP-2 a general blockchain identification scheme is defined. This is the
+implementation of CAIP-2 for the Avalanche Ecosystem. 
+Blockchains in the "avax" namespace are validated by their `blockchainID`. 
+The `blockchainID` in Avalanche refers to the [txID][] that created the 
+blockchain on the Avalanche P-Chain.
+These blockchain IDs require transformations to be used as conformant CAIP-2
+references.
+
+## Syntax
+
+The namespace "avax" refers to the Avalanche open-source blockchain platform.
+
+### Reference Definition
+
+The definition for this namespace will use the `blockchainID` as an identifier
+for different Avalanche chains. Since the P-Chain's `blockchainID` is the same 
+on Testnet and Mainnet, to ensure uniqueness, a testnet prefix is introduced 
+for chains on the [Fuji Testnet][].  
+
+The method for calculating the chain ID is as follows with pseudo-code:
+
+```
+first_32_chars(base64url(sha256(concat(testnet_prefix, blockchain_id))))
+```
+
+- `blockchain_id` = `txID` that created the blockchain on the Avalanche P-Chain
+- `testnet_prefix`= `fuji` when the chain was created on the Fuji Testnet; 
+  empty string otherwise
+- `concat`= a string concatenation function
+- `sha256`= a SHA256 hash function
+- `base64url`= a Base64URL encoder
+- `first_32_chars`= a function to extract the first 32 characters of the
+  resulting string and dropping the rest
+
+### Resolution Method
+
+To resolve a blockchain reference for the Avalanche namespace, make a JSON-RPC 
+request to the [Info API][] with method `info.getBlockchainID`, for example:
+
+```jsonc
+// Request
+{
+    "jsonrpc":"2.0",
+    "id"     :1,
+    "method" :"info.getBlockchainID",
+    "params": {
+        "alias":"C"
+    }
+}
+
+// Response
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": {
+    "blockchainID": "2q9e4r6Mu3U68nU1fYjgbR6JvwrRx36CohpAX5UQxse55x1Q5"
+  }
+}
+```
+
+For example, this Node.js code transforms the above response into a CAIP-2 identifier:
+
+```javascript
+const isTestnet = false;
+const blockchainID = "2q9e4r6Mu3U68nU1fYjgbR6JvwrRx36CohpAX5UQxse55x1Q5";
+const testnetPrefix = isTestnet ? 'fuji' : '';
+const hash = createHash('sha256')
+              .update(testnetPrefix + blockchainID)
+              .digest('base64url')
+              .substring(0, 32);
+const identifier = "avax:" + hash;
+
+console.log(identifier); // prints "avax:8aDU0Kqh-5d23op-B-r-4YbQFRbsgF9a"
+```
+
+### Backwards Compatibility
+
+Not applicable
+
+## Test Cases
+
+This is a list of manually composed examples
+
+```
+# Avalanche P Chain Mainnet
+# blockchainID: 11111111111111111111111111111111LpoYY
+avax:Rr9hnPVPxuUvrdCul-vjEsU1zmqKqRDo
+
+# Avalanche C Chain Mainnet
+# blockchainID: 2q9e4r6Mu3U68nU1fYjgbR6JvwrRx36CohpAX5UQxse55x1Q5
+avax:8aDU0Kqh-5d23op-B-r-4YbQFRbsgF9a
+
+# Avalanche X Chain Mainnet
+# blockchainID: 2oYMBNV4eNHyqk2fjjV5nVQLDbtmNJzq5s3qs3Lo6ftnC6FByM
+avax:imji8papUf2EhV3le337w1vgFauqkJg-
+
+# Avalanche P Chain Testnet
+# blockchainID: 11111111111111111111111111111111LpoYY
+avax:Sj7NVE3jXTbJvwFAiu7OEUo_8g8ctXMG
+
+# Avalanche C Chain Testnet
+# blockchainID: yH8D7ThNJkxmtkuv2jgBa4P1Rn3Qpr4pPr7QYNfcdoS6k6HWp
+avax:YRLfeDBJpfEqUWe2FYR1OpXsnDDZeKWd
+
+# Avalanche X Chain Testnet
+# blockchainID: 2JVSBoinj9C2J33VntvzYtVJNZdN2NKiwwKjcumHUWEb5DbBrm
+avax:8AJTpRj3SAqv1e80Mtl9em08LhvKEbkl
+
+```
+
+## References
+
+- [Fuji Testnet][] - Fuji Testnet in Avalanche official documentation
+- [Info API][] - Info API reference in Avalanche official documentation
+- [txID][] - Create Chain TX reference in Avalanche official documentation
+
+[CAIP-2]: https://github.com/ChainAgnostic/CAIPs/blob/master/CAIPs/caip-2.md
+[Fuji Testnet]: https://docs.avax.network/learn/avalanche/fuji
+[Info API]: https://docs.avax.network/reference/avalanchego/info-api
+[txID]: https://docs.avax.network/reference/avalanchego/p-chain/txn-format#unsigned-create-chain-tx
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).