ERC-6381 — Public NFT Emote Repository

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ERC-6381: Public NFT Emote Repository

ERC-6381 standardises an on-chain emoji-reaction primitive: any user can emote/un-emote on any NFT (across any contract), and the repository tracks the count per (collection, tokenId, emoji). Used for:

• Social NFT discovery — hot NFTs surfaced by reaction count.
• Decentralised "likes" — censorship-resistant reactions outside platform-specific systems.
• Community curation — collective reactions weight indexer ranking algorithms.
• Reputation signals — patterns of emoji usage over a wallet's history form a reputation profile.

Critically, the repository is a separate singleton contract — not part of any NFT contract. NFT collections don't need to opt in; users emote via the repository, which works against any collection / tokenId.

Required Interface

interface IERC6381 {
    event Emoted(address indexed emoter, address indexed collection, uint256 indexed tokenId,
                 string emoji, bool on);

    function emote(address collection, uint256 tokenId, string calldata emoji, bool on) external;
    function emoteCountOf(address collection, uint256 tokenId, string calldata emoji)
        external view returns (uint256);
    function hasEmoterUsedEmote(address collection, uint256 tokenId, string calldata emoji,
                                address emoter) external view returns (bool);
}

The emoji is a UTF-8 string (e.g. "👍", "🔥", "❤️"); the on flag toggles emote/un-emote. Counts are aggregated per (collection, tokenId, emoji).

Neo Equivalent: Standalone Repository Contract

The Neo port is a single contract handling reactions across any NEP-11. No coupling to the NFT contracts themselves.

public static void Emote(UInt160 collection, ByteString tokenId, string emoji, bool on)
{
    var emoter = Runtime.CallingScriptHash;
    if (!Runtime.CheckWitness(emoter)) throw new Exception("EMOTE:NoAuth");

    var userKey = UserEmoteKey(collection, tokenId, emoji, emoter);
    var countKey = CountKey(collection, tokenId, emoji);
    var alreadyEmoted = Storage.Get(Storage.CurrentContext, userKey) is not null;

    if (on && !alreadyEmoted)
    {
        Storage.Put(Storage.CurrentContext, userKey, 1);
        var count = (BigInteger)(Storage.Get(Storage.CurrentContext, countKey) ?? ByteString.Empty);
        Storage.Put(Storage.CurrentContext, countKey, count + 1);
        OnEmoted(emoter, collection, tokenId, emoji, true);
    }
    else if (!on && alreadyEmoted)
    {
        Storage.Delete(Storage.CurrentContext, userKey);
        var count = (BigInteger)(Storage.Get(Storage.CurrentContext, countKey) ?? ByteString.Empty);
        Storage.Put(Storage.CurrentContext, countKey, count - 1);
        OnEmoted(emoter, collection, tokenId, emoji, false);
    }
}

public static BigInteger EmoteCountOf(UInt160 collection, ByteString tokenId, string emoji)
    => (BigInteger)(Storage.Get(Storage.CurrentContext, CountKey(collection, tokenId, emoji)) ?? ByteString.Empty);

ERC-6381 (Ethereum)	Neo Equivalent	Notes
emote(collection, tokenId, emoji, on)	Emote(...) emoter-witness-checked	Toggle pattern
emoteCountOf(...)	EmoteCountOf(...) view	Direct port
hasEmoterUsedEmote(...)	HasEmoterUsedEmote(...) view	Direct port
Singleton repository	Single deployed contract works for all NEP-11 collections	Same architecture

Composition

• ERC-7053 — media indexing. Reactions inform indexer-side ranking weights.
• ERC-5023 — shareable NFT. Reactions on shared NFTs aggregate across all holders.
• ERC-5489 — NFT hyperlinks. Hot reactions surface to the top of NFT detail pages.

Migration Notes

For social-NFT platforms:

1. Deploy the repository contract once; it serves all NEP-11 NFTs.
2. dApps integrate by calling Emote(...) from the user's wallet and querying EmoteCountOf for display.
3. Reaction counts are global — any indexer or marketplace can read them without per-NFT-contract integration.

The on-chain footprint is small per emote (~50 GAS); for high- traffic NFTs (millions of reactions) consider sharding by emoji or introducing a per-NFT subkey rotation strategy.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract ERC6381 {
    mapping(address => mapping(uint256 => mapping(string => uint256))) public emoteCount;
    mapping(address => mapping(uint256 => mapping(string => mapping(address => bool)))) public hasEmoted;

    event Emoted(address indexed emoter, address indexed collection, uint256 indexed tokenId,
                 string emoji, bool on);

    function emote(address collection, uint256 tokenId, string calldata emoji, bool on) external {
        bool current = hasEmoted[collection][tokenId][emoji][msg.sender];
        if (on && !current) {
            hasEmoted[collection][tokenId][emoji][msg.sender] = true;
            emoteCount[collection][tokenId][emoji]++;
            emit Emoted(msg.sender, collection, tokenId, emoji, true);
        } else if (!on && current) {
            hasEmoted[collection][tokenId][emoji][msg.sender] = false;
            emoteCount[collection][tokenId][emoji]--;
            emit Emoted(msg.sender, collection, tokenId, emoji, false);
        }
    }
}

using System;
using System.ComponentModel;
using System.Numerics;
using Neo;
using Neo.SmartContract.Framework;
using Neo.SmartContract.Framework.Attributes;
using Neo.SmartContract.Framework.Native;
using Neo.SmartContract.Framework.Services;

namespace R3E.Examples;

[DisplayName("EmoteRepository")]
[ContractPermission("*", "*")]
public class EmoteRepository : SmartContract
{
    private const byte Prefix_Count = 0x10;
    private const byte Prefix_User  = 0x11;

    [DisplayName("Emoted")]
    public static event Action<UInt160, UInt160, ByteString, string, bool> OnEmoted;

    public static void Emote(UInt160 collection, ByteString tokenId, string emoji, bool on)
    {
        var emoter = Runtime.CallingScriptHash;
        if (!Runtime.CheckWitness(emoter)) throw new Exception("EMOTE:NoAuth");

        var userKey  = UserEmoteKey(collection, tokenId, emoji, emoter);
        var countKey = CountKey(collection, tokenId, emoji);
        var already = Storage.Get(Storage.CurrentContext, userKey) is not null;

        if (on && !already)
        {
            Storage.Put(Storage.CurrentContext, userKey, 1);
            var count = (BigInteger)(Storage.Get(Storage.CurrentContext, countKey) ?? ByteString.Empty);
            Storage.Put(Storage.CurrentContext, countKey, count + 1);
            OnEmoted(emoter, collection, tokenId, emoji, true);
        }
        else if (!on && already)
        {
            Storage.Delete(Storage.CurrentContext, userKey);
            var count = (BigInteger)(Storage.Get(Storage.CurrentContext, countKey) ?? ByteString.Empty);
            Storage.Put(Storage.CurrentContext, countKey, count - 1);
            OnEmoted(emoter, collection, tokenId, emoji, false);
        }
    }

    public static BigInteger EmoteCountOf(UInt160 collection, ByteString tokenId, string emoji)
        => (BigInteger)(Storage.Get(Storage.CurrentContext, CountKey(collection, tokenId, emoji)) ?? ByteString.Empty);

    public static bool HasEmoterUsedEmote(UInt160 collection, ByteString tokenId, string emoji, UInt160 emoter)
        => Storage.Get(Storage.CurrentContext, UserEmoteKey(collection, tokenId, emoji, emoter)) is not null;

    private static byte[] CountKey(UInt160 collection, ByteString tokenId, string emoji)
        => new byte[] { Prefix_Count }.Concat(collection).Concat(tokenId).Concat((ByteString)emoji);

    private static byte[] UserEmoteKey(UInt160 collection, ByteString tokenId, string emoji, UInt160 emoter)
        => new byte[] { Prefix_User }.Concat(collection).Concat(tokenId)
            .Concat((ByteString)emoji).Concat(emoter);
}