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Implement signed byte conversion for checksum to fix #3765 #1442

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Implement signed byte conversion for checksum to fix #3765 #1442

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Implement signed byte conversion for checksum to fix #3765
brentspine Dec 16, 2025
5b9299b
Merge branch 'master' into patch-1
extremeheat Jan 26, 2026
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7 changes: 6 additions & 1 deletion src/client/chat.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,11 @@ const concat = require('../transforms/binaryStream').concat
const { processNbtMessage } = require('prismarine-chat')
const messageExpireTime = 420000 // 7 minutes (ms)

const toSignedByte = (value) => {
const byte = value & 0xff
return byte > 127 ? byte - 256 : byte
}
Comment on lines +7 to +10
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Copilot AI Dec 16, 2025

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Consider moving the toSignedByte function to src/datatypes/checksums.js and exporting it alongside computeChatChecksum. This would improve code organization by grouping related checksum functionality together and make the function reusable if needed elsewhere. The function is specifically designed to handle the signed byte requirement for checksums in the Minecraft protocol.

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@brentspine brentspine Dec 16, 2025

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@copilot coauthor pr #1442 based on this this feedback


function isFormatted (message) {
// This should match the ChatComponent.isDecorated function from Vanilla
try {
Expand Down Expand Up @@ -377,7 +382,7 @@ module.exports = function (client, options) {
salt: options.salt,
argumentSignatures: canSign ? signaturesForCommand(command, options.timestamp, options.salt, options.preview, acknowledgements) : [],
messageCount: client._lastSeenMessages.pending,
checksum: computeChatChecksum(client._lastSeenMessages), // 1.21.5+
checksum: toSignedByte(computeChatChecksum(client._lastSeenMessages)), // 1.21.5+
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@extremeheat extremeheat Jan 26, 2026

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This branch specifically covers the chat commands only. Is this intentional? Your linked issue PrismarineJS/mineflayer#3765 seems to hint at normal chat messages too

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@brentspine brentspine Feb 26, 2026

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I only encountered this with commands. Would you mind using my fix yourself? It's easier than me doing it

acknowledged
}
client.write((mcData.supportFeature('seperateSignedChatCommandPacket') && canSign) ? 'chat_command_signed' : 'chat_command', chatPacket)
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