feat: Creates design doc for enabling access to hts token evm address

docs/design/hts_address_tx_receipt.md

@@ -0,0 +1,62 @@
+# HTS Token Creation via SystemContract Receipt Enhancement
+
+## Purpose
+The purpose of this enhancement is to improve the interoperability between Hedera Token Service (HTS) and Ethereum-compatible tools, like ethers, by ensuring access to the necessary information about newly created tokens, in this case token address. This change specifically addresses the gap in Web3 tooling support when creating tokens through HTS precompile contracts, making user experience smoother.
+
+
+## Problem Statement
+When users create tokens (fungible and non-fungible) by directly calling the 0x167 contract there is no way for them to get the evm address of the newly created token via standard EVM tooling e.g ethers. This is because the transaction receipt's contractAddress field is not being populated with the HTS token address, since essentially the operations is just a contract call, but not a contract create (deploy).
+
+## Current Behaviour
+
+Currently, when creating a token via HTS the address of the system contract is returned as a contractAddress in the transaction receipt.
+
+## Proposed Solution
+
+### Technical Details
+
+### 1. Function Signature Detection
+
+Detect in the transactionResponse from the mirror node, if the transaction was calling any of the HTS methods - createFungibleToken/createNonFungibleToken/createFungibleTokenWithCustomFees/createNonFungibleTokenWithCustomFees
+
+N.B The following forms of the [HTS system contract](https://github.com/hashgraph/hedera-smart-contracts/tree/v0.10.1/contracts/system-contracts/hedera-token-service) create token function selectors will be supported. This is as of the 0.56 version of the services.
+
+```javascript
+const HTS_CREATE_FUNCTIONS_SIGNATURE = [
+  "createFungibleToken(...)",
+  "createNonFungibleToken(...)",
+  "createFungibleTokenWithCustomFees(...)",
+  "createNonFungibleTokenWithCustomFees(...)"
+];
+const functionSelector = receiptResponse.function_parameters.substring(0, FUNCTION_SELECTOR_CHAR_LENGTH);
+const isTokenCreation = HTS_CREATE_FUNCTIONS_SIGNATURE.some(signature => 
+  Utils.calculateFunctionSelector(signature) === functionSelector
+);
+```
+
+### 2. Extract the token address from the `call_result` field in the transaction response. 
+The extractions can performed with string matching logic since we know what the function response is beforehand and we know the last 40 characters of the response are the token address.
+
+Example call_result. First 64 characters excluding 0x prefix are the response code, second 64 characters are the token address:
+```json
+"call_result": "0x0000000000000000000000000000000000000000000000000000000000000016000000000000000000000000000000000000000000000000000000000000040a"
+```
+
+```javascript
+const tokenAddress = receiptResponse.call_result.substring(receiptResponse.call_result.length - 40);
+```
+After extraction, the expected output is:
+```
+"0x000000000000000000000000000000000000000000000000000000000000040a"
+```
+
+### 3. Add the token address to the receipt
+
+
+## Testing Requirements
+
+### Acceptance tests
+   1. Test creation of fungible token via ethers and correct receipt response
+   2. Test creation of non fungible token via ethers and correct receipt response
+   3. Test creation of fungible token with custom fees via ethers and correct receipt response
+   4. Test creation of non fungible token with custom fees via ethers and correct receipt response