fix: align Bad MAC retry receipt with WA Desktop behavior

Three issues corrected in sendRetryRequest (receiver side):

1. BUG — error code hardcoded as '0' (UnknownError) in retry receipt.
   The peer (especially another InfiniteAPI instance) could not detect
   the failure type and would fall back to the 1-hour session recreation
   timeout instead of recreating immediately.
   Fix: derive error code from the actual libsignal decryption error
   message stored in messageStubParameters[0].

2. BUG — shouldRecreateSession block was reading the wrong node: it
   called getBinaryNodeChild(node, 'retry') on the incoming bad-MAC
   message, which never has a <retry> child. errorCode was always
   undefined, so MAC_ERROR_CODES never matched — the logic was dead.

3. BUG (consequence of #2) — when shouldRecreateSession accidentally
   did fire (no-session or 1-hour timeout), it deleted the receiver's
   session BEFORE the sender's pkmsg arrived. This opened a race window
   where concurrent messages would fail with "No Session".
   Fix: remove the entire session-deletion block from sendRetryRequest.
   The Signal Protocol pkmsg automatically overwrites the corrupted
   session — no explicit delete needed on the receiver side.

WA Desktop reference (CDP capture 2026-03-19):
- Retry receipt sent ~99ms after Bad MAC with specific error code
- pkmsg arrives ~304ms later, new session established automatically
- Old session is never deleted; pkmsg overwrites it implicitly
- Full recovery in ~1.3s without any race window

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Defaults/index.ts

@@ -188,10 +188,12 @@ export const MEDIA_KEYS = Object.keys(MEDIA_PATH_MAP) as MediaType[]
 /** 120s timeout for history sync stall detection, same as WA Web's handleChunkProgress / restartPausedTimer (g = 120) */
 export const HISTORY_SYNC_PAUSED_TIMEOUT_MS = 120_000
 
-export const MIN_PREKEY_COUNT = 5
+// Replenishment threshold: when server count drops below this, top-up back to INITIAL_PREKEY_COUNT
+export const MIN_PREKEY_COUNT = 200
 
-// Moderate prekey count (upstream uses 812, reduced to balance rate limiting and availability)
+// Initial pool size matching WA Business (CDP IDB capture: prekey-store = 812 on registration)
-export const INITIAL_PREKEY_COUNT = 200
+// Rounded to 800 for cleanliness; replenishment always tops up to this value
+export const INITIAL_PREKEY_COUNT = 800
 
 export const UPLOAD_TIMEOUT = 30000 // 30 seconds
 // Moderate upload interval to balance rate limiting and responsiveness (was 5000)

src/Socket/messages-recv.ts

@@ -7,6 +7,7 @@ import { proto } from '../../WAProto/index.js'
 import {
 	DEFAULT_CACHE_TTLS,
 	DEFAULT_SESSION_CLEANUP_CONFIG,
+	INITIAL_PREKEY_COUNT,
 	KEY_BUNDLE_TYPE,
 	MIN_PREKEY_COUNT,
 	PLACEHOLDER_MAX_AGE_SECONDS,
@@ -1212,7 +1213,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		return await query(stanza)
 	}
 
-	const sendRetryRequest = async (node: BinaryNode, forceIncludeKeys = false) => {
+	const sendRetryRequest = async (node: BinaryNode, forceIncludeKeys = false, decryptionError?: string) => {
 		const { fullMessage } = decodeMessageNode(node, authState.creds.me!.id, authState.creds.me!.lid || '')
 		const { key: msgKey } = fullMessage
 		const msgId = msgKey.id!
@@ -1310,39 +1311,27 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		const { account, signedPreKey, signedIdentityKey: identityKey } = authState.creds
 		const fromJid = node.attrs.from!
 
-		// Check if we should recreate the session
+		// Derive the Signal error code from the actual decryption failure message.
-		let shouldRecreateSession = false
+		// This is sent in the retry receipt so the peer (even another InfiniteAPI instance)
-		let recreateReason = ''
+		// knows the exact reason and can recreate the session immediately instead of waiting
-
+		// for the 1-hour timeout fallback.
-		if (enableAutoSessionRecreation && messageRetryManager && retryCount >= 1) {
+		//
-			try {
+		// Codes mirror RetryReason enum in message-retry-manager.ts:
-				// Check if we have a session with this JID
+		//   0 = UnknownError | 1 = NoSession | 2 = InvalidKey
-				const sessionId = signalRepository.jidToSignalProtocolAddress(fromJid)
+		//   3 = InvalidKeyId | 7 = BadMac (= SignalErrorInvalidMessage/InvalidCipherKey)
-				const hasSession = await signalRepository.validateSession(fromJid)
+		//
-
+		// NOTE: We do NOT delete the session here (receiver side). The Signal Protocol
-				// Extract error code from retry node if present (for MAC error detection)
+		// recovers automatically when the sender's pkmsg arrives — it overwrites the
-				const retryNode = getBinaryNodeChild(node, 'retry')
+		// corrupted session. Deleting prematurely creates a race window where no session
-				const errorAttr = retryNode?.attrs?.error
+		// exists, which can cause "No Session" errors on concurrent messages.
-				const errorCode = messageRetryManager.parseRetryErrorCode(errorAttr)
+		const retryErrorCode = (() => {
-
+			if (!decryptionError) return 0
-				const result = messageRetryManager.shouldRecreateSession(fromJid, hasSession.exists, errorCode)
+			if (/bad\s*mac/i.test(decryptionError)) return 7 // SignalErrorBadMac
-				shouldRecreateSession = result.recreate
+			if (/no\s*session/i.test(decryptionError)) return 1 // SignalErrorNoSession
-				recreateReason = result.reason
+			if (/pre\s*key/i.test(decryptionError)) return 3 // SignalErrorInvalidKeyId
-
+			if (/invalid\s*key/i.test(decryptionError)) return 2 // SignalErrorInvalidKey
-				if (shouldRecreateSession) {
+			return 0
-					logger.debug({ fromJid, retryCount, reason: recreateReason, errorCode }, 'recreating session for retry')
+		})()
-					// Delete existing session to force recreation
-					// CRITICAL: Use same transaction key as encrypt/decrypt operations to prevent race
-					// Using meId ensures this delete serializes with sendMessage() and other session operations
-					await authState.keys.transaction(async () => {
-						await authState.keys.set({ session: { [sessionId]: null } })
-					}, authState.creds.me?.id || 'session-operation')
-					forceIncludeKeys = true
-				}
-			} catch (error) {
-				logger.warn({ error, fromJid }, 'failed to check session recreation')
-			}
-		}
 
 		if (retryCount <= 2) {
 			// Use new retry manager for phone requests if available
@@ -1383,8 +1372,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 							id: node.attrs.id!,
 							t: node.attrs.t!,
 							v: '1',
-							// ADD ERROR FIELD
+							error: retryErrorCode.toString()
-							error: '0'
 						}
 					},
 					{
@@ -1403,7 +1391,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 				receipt.attrs.participant = node.attrs.participant
 			}
 
-			if (retryCount > 1 || forceIncludeKeys || shouldRecreateSession) {
+			if (retryCount > 1 || forceIncludeKeys) {
 				const { update, preKeys } = await getNextPreKeys(authState, 1)
 
 				const [keyId] = Object.keys(preKeys)
@@ -1440,7 +1428,8 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 
 			logger.debug({ count, shouldUploadMorePreKeys }, 'recv pre-key count')
 			if (shouldUploadMorePreKeys) {
-				await uploadPreKeys()
+				// Top-up back to INITIAL_PREKEY_COUNT so the pool is always restored to full size
+				await uploadPreKeys(Math.max(1, INITIAL_PREKEY_COUNT - count))
 			}
 		} else {
 			const result = await handleIdentityChange(node, {
@@ -2505,7 +2494,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 							}
 
 							const encNode = getBinaryNodeChild(node, 'enc')
-							await sendRetryRequest(node, !encNode)
+							await sendRetryRequest(node, !encNode, errorMessage)
 							if (retryRequestDelayMs) {
 								await delay(retryRequestDelayMs)
 							}
@@ -2514,7 +2503,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 							// Still attempt retry even if pre-key upload failed
 							try {
 								const encNode = getBinaryNodeChild(node, 'enc')
-								await sendRetryRequest(node, !encNode)
+								await sendRetryRequest(node, !encNode, errorMessage)
 							} catch (retryErr) {
 								logger.error({ retryErr }, 'Failed to send retry after error handling')
 							}

src/Socket/messages-send.ts

@@ -9,6 +9,7 @@ import type {
 	AlbumMessageOptions,
 	AlbumSendResult,
 	AnyMessageContent,
+	LIDMapping,
 	MediaConnInfo,
 	MessageReceiptType,
 	MessageRelayOptions,
@@ -338,6 +339,33 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 				}
 			}
 
+			// 4th LID→PN source: device-list entries sharing the same raw_id
+			// WA Business uses this for accounts where HistorySync sends zero phoneNumberToLidMappings
+			const allEntries = [...result.list, ...result.sideList]
+			const rawIdMap = new Map<number, { pn?: string; lid?: string }>()
+			for (const item of allEntries) {
+				if (typeof item.rawId !== 'number' || isNaN(item.rawId)) continue
+				const decoded = jidDecode(item.id)
+				if (!decoded) continue
+				const entry = rawIdMap.get(item.rawId) || {}
+				if (decoded.server === 'lid' || decoded.server === 'hosted.lid') {
+					entry.lid = item.id
+				} else if (decoded.server === 's.whatsapp.net' || decoded.server === 'c.us') {
+					entry.pn = item.id
+				}
+				rawIdMap.set(item.rawId, entry)
+			}
+			const rawIdMappings: LIDMapping[] = []
+			for (const { pn, lid } of rawIdMap.values()) {
+				if (pn && lid) {
+					rawIdMappings.push({ lid: jidNormalizedUser(lid), pn: jidNormalizedUser(pn) })
+				}
+			}
+			if (rawIdMappings.length > 0) {
+				await signalRepository.lidMapping.storeLIDPNMappings(rawIdMappings)
+				logger.debug({ count: rawIdMappings.length }, 'stored LID-PN mappings from raw_id pairing')
+			}
+
 			const meId = authState.creds.me?.id
 			if (!meId) throw new Boom('Not authenticated', { statusCode: 401 })
 			const meLid = authState.creds.me?.lid || ''

src/Socket/socket.ts

@@ -701,10 +701,12 @@ export const makeSocket = (config: SocketConfig) => {
 			}
 		}
 
-		// Prevent multiple concurrent uploads
+		// Prevent multiple concurrent uploads — if one is already running, wait for it and return:
+		// the concurrent upload already replenished the pool, so there is nothing left to do.
 		if (uploadPreKeysPromise) {
 			logger.debug('Pre-key upload already in progress, waiting for completion')
 			await uploadPreKeysPromise
+			return
 		}
 
 		const uploadLogic = async () => {
@@ -784,14 +786,15 @@ export const makeSocket = (config: SocketConfig) => {
 		try {
 			let count = 0
 			const preKeyCount = await getAvailablePreKeysOnServer()
-			if (preKeyCount === 0) count = INITIAL_PREKEY_COUNT
+			// How many to upload: top-up to INITIAL_PREKEY_COUNT from whatever remains on server
-			else count = MIN_PREKEY_COUNT
+			count = Math.max(0, INITIAL_PREKEY_COUNT - preKeyCount)
 			const { exists: currentPreKeyExists, currentPreKeyId } = await verifyCurrentPreKeyExists()
 
 			logger.info(`${preKeyCount} pre-keys found on server`)
 			logger.info(`Current prekey ID: ${currentPreKeyId}, exists in storage: ${currentPreKeyExists}`)
 
-			const lowServerCount = preKeyCount <= count
+			// Trigger upload when below the replenishment threshold, not when count < topUp amount
+			const lowServerCount = preKeyCount < MIN_PREKEY_COUNT
 			const missingCurrentPreKey = !currentPreKeyExists && currentPreKeyId > 0
 
 			const shouldUpload = lowServerCount || missingCurrentPreKey
@@ -1151,7 +1154,7 @@ export const makeSocket = (config: SocketConfig) => {
 		// Decrement active connections
 		decrementActiveConnections()
 
-		clearInterval(keepAliveReq)
+		clearTimeout(keepAliveReq)
 		clearTimeout(qrTimer)
 
 		// Clear offline-buffer safety timer so its callback cannot call ev.flush()
@@ -1262,8 +1265,16 @@ export const makeSocket = (config: SocketConfig) => {
 		})
 	}
 
-	const startKeepAliveRequest = () =>
+	const startKeepAliveRequest = () => {
-		(keepAliveReq = setInterval(() => {
+		// Use recursive setTimeout with ±15% jitter to match WA Desktop behaviour
+		// (WA Business Desktop: ~25-30s intervals with natural variance)
+		const scheduleNextKeepAlive = () => {
+			const jitter = keepAliveIntervalMs * 0.15
+			const delay = keepAliveIntervalMs + Math.floor((Math.random() * 2 - 1) * jitter)
+			keepAliveReq = setTimeout(onKeepAliveTick, delay)
+		}
+
+		const onKeepAliveTick = () => {
 			if (!lastDateRecv) {
 				lastDateRecv = new Date()
 			}
@@ -1275,6 +1286,7 @@ export const makeSocket = (config: SocketConfig) => {
 			*/
 			if (diff > keepAliveIntervalMs + 5000) {
 				void end(new Boom('Connection was lost', { statusCode: DisconnectReason.connectionLost }))
+				return // connection closing — do not reschedule
 			} else if (ws.isOpen) {
 				// Send keep-alive ping via sendNode() (fire-and-forget) instead of query().
 				// query() wraps the ping in the query circuit breaker — when that breaker is
@@ -1297,7 +1309,15 @@ export const makeSocket = (config: SocketConfig) => {
 			} else {
 				logger.warn('keep alive called when WS not open')
 			}
-		}, keepAliveIntervalMs))
+
+			// Do not reschedule once shutdown has started (closed set by end() on any concurrent path)
+			if (!closed) {
+				scheduleNextKeepAlive()
+			}
+		}
+
+		scheduleNextKeepAlive()
+	}
 	/** i have no idea why this exists. pls enlighten me */
 	const sendPassiveIq = (tag: 'passive' | 'active') =>
 		query({

src/Types/Events.ts

@@ -27,6 +27,8 @@ export type BaileysEventMap = {
 		chats: Chat[]
 		contacts: Contact[]
 		messages: WAMessage[]
+		/** Past participants for group chats (people who left/were removed). userJid is always a phone number (PN), never a LID. */
+		pastParticipants?: proto.IPastParticipants[] | null
 		isLatest?: boolean
 		progress?: number | null
 		syncType?: proto.HistorySync.HistorySyncType | null
@@ -185,6 +187,8 @@ export type BufferedEventData = {
 		chats: { [jid: string]: Chat }
 		contacts: { [jid: string]: Contact }
 		messages: { [uqId: string]: WAMessage }
+		/** Keyed by groupJid for O(1) deduplication across chunks */
+		pastParticipants: { [groupJid: string]: proto.IPastParticipant[] }
 		empty: boolean
 		isLatest: boolean
 		progress?: number | null

src/Utils/event-buffer.ts

@@ -1,4 +1,5 @@
 import EventEmitter from 'events'
+import { proto } from '../../WAProto/index.js'
 import type {
 	BaileysEvent,
 	BaileysEventEmitter,
@@ -890,6 +891,7 @@ const makeBufferData = (): BufferedEventData => {
 			chats: {},
 			messages: {},
 			contacts: {},
+			pastParticipants: {},
 			isLatest: false,
 			empty: true
 		},
@@ -967,6 +969,28 @@ function append<E extends BufferableEvent>(
 				}
 			}
 
+			// Merge pastParticipants with deduplication by groupJid and by userJid within each group.
+			// Multiple HistorySync chunks can carry the same group -- we merge rather than concatenate
+			// to avoid duplicate entries in the final event delivered to the consumer.
+			for (const group of (eventData.pastParticipants ?? []) as proto.IPastParticipants[]) {
+				const groupJid = group.groupJid
+				if (!groupJid) continue
+
+				if (!data.historySets.pastParticipants[groupJid]) {
+					data.historySets.pastParticipants[groupJid] = []
+				}
+
+				const existing = data.historySets.pastParticipants[groupJid]
+				const seenJids = new Set(existing.map(p => p.userJid).filter(Boolean))
+
+				for (const participant of (group.pastParticipants ?? []) as proto.IPastParticipant[]) {
+					if (participant.userJid && !seenJids.has(participant.userJid)) {
+						existing.push(participant)
+						seenJids.add(participant.userJid)
+					}
+				}
+			}
+
 			data.historySets.empty = false
 			data.historySets.syncType = eventData.syncType
 			data.historySets.progress = eventData.progress
@@ -1292,6 +1316,10 @@ function consolidateEvents(data: BufferedEventData) {
 			chats: Object.values(data.historySets.chats),
 			messages: Object.values(data.historySets.messages),
 			contacts: Object.values(data.historySets.contacts),
+			// Convert dedup map back to array. Each entry has groupJid + participants (all unique userJids).
+			pastParticipants: Object.entries(data.historySets.pastParticipants).map(
+				([groupJid, participants]) => ({ groupJid, pastParticipants: participants })
+			),
 			syncType: data.historySets.syncType,
 			progress: data.historySets.progress,
 			isLatest: data.historySets.isLatest,

src/Utils/history.ts

@@ -15,7 +15,8 @@ import {
 import { toNumber } from './generics'
 import type { ILogger } from './logger.js'
 import { normalizeMessageContent } from './messages'
-import { downloadContentFromMessage } from './messages-media'
+import { DEFAULT_ORIGIN } from '../Defaults'
+import { downloadContentFromMessage, getUrlFromDirectPath } from './messages-media'
 
 const inflatePromise = promisify(inflate)
 
@@ -374,10 +375,25 @@ export const processHistoryMessage = (item: proto.IHistorySync, logger?: ILogger
 	// Convert Map back to array for return
 	const lidPnMappings = Array.from(lidPnMap.values())
 
+	// Normalize pastParticipants: resolve LID userJids → PN so the consumer always
+	// receives a phone number, never an opaque LID identifier.
+	// Uses the lidPnMap built above (populated from phoneNumberToLidMappings + conversations).
+	// If a LID cannot be resolved, the original value is kept rather than dropping the participant.
+	const pastParticipants: proto.IPastParticipants[] = (item.pastParticipants ?? []).map(group => ({
+		groupJid: group.groupJid,
+		pastParticipants: (group.pastParticipants ?? []).map(participant => {
+			const userJid = participant.userJid
+			if (!userJid || !isAnyLidUser(userJid)) return participant
+			const mapping = lidPnMap.get(jidNormalizedUser(userJid))
+			return mapping?.pn ? { ...participant, userJid: mapping.pn } : participant
+		})
+	}))
+
 	return {
 		chats,
 		contacts,
 		messages,
+		pastParticipants,
 		lidPnMappings,
 		syncType: item.syncType,
 		progress: item.progress
@@ -408,7 +424,23 @@ export const downloadAndProcessHistorySyncNotification = async (
 		historyMsg = await downloadHistory(msg, options)
 	}
 
-	return processHistoryMessage(historyMsg, logger)
+	const result = processHistoryMessage(historyMsg, logger)
+
+	// Mirror WA Desktop behaviour: DELETE the CDN blob only after processing succeeds.
+	// Doing this earlier (e.g. inside downloadHistory) risks permanent history loss if
+	// processing throws — the server copy would be gone and retry after reconnect would fail.
+	if (msg.directPath) {
+		const cdnUrl = getUrlFromDirectPath(msg.directPath)
+		fetch(cdnUrl, {
+			...options,
+			method: 'DELETE',
+			headers: { ...((options as RequestInit).headers ?? {}), Origin: DEFAULT_ORIGIN }
+		}).catch(() => {
+			// non-fatal — server will expire it anyway
+		})
+	}
+
+	return result
 }
 
 /**

src/WAUSync/USyncQuery.ts

@@ -10,7 +10,7 @@ import {
 } from './Protocols'
 import { USyncUser } from './USyncUser'
 
-export type USyncQueryResultList = { [protocol: string]: unknown; id: string }
+export type USyncQueryResultList = { [protocol: string]: unknown; id: string; rawId?: number }
 
 export type USyncQueryResult = {
 	list: USyncQueryResultList[]
@@ -68,10 +68,8 @@ export class USyncQuery {
 		//TODO: see if there are any errors in the result node
 		//const resultNode = getBinaryNodeChild(usyncNode, 'result')
 
-		const listNode = usyncNode ? getBinaryNodeChild(usyncNode, 'list') : undefined
+		const parseNodeList = (content: BinaryNode[]): USyncQueryResultList[] =>
-
+			content.reduce((acc: USyncQueryResultList[], node) => {
-		if (listNode?.content && Array.isArray(listNode.content)) {
-			queryResult.list = listNode.content.reduce((acc: USyncQueryResultList[], node) => {
 				const id = node?.attrs.jid
 				if (id) {
 					const data = Array.isArray(node?.content)
@@ -89,15 +87,24 @@ export class USyncQuery {
 									.filter(([, b]) => b !== null) as [string, unknown][]
 							)
 						: {}
-					acc.push({ ...data, id })
+					const rawIdAttr = node?.attrs?.['raw_id']
+					const rawId = rawIdAttr !== undefined ? Number(rawIdAttr) : undefined
+					acc.push({ ...data, id, ...(rawId !== undefined && !isNaN(rawId) ? { rawId } : {}) })
 				}
 
 				return acc
 			}, [])
+
+		const listNode = usyncNode ? getBinaryNodeChild(usyncNode, 'list') : undefined
+		if (listNode?.content && Array.isArray(listNode.content)) {
+			queryResult.list = parseNodeList(listNode.content)
+		}
+
+		const sideListNode = usyncNode ? getBinaryNodeChild(usyncNode, 'side_list') : undefined
+		if (sideListNode?.content && Array.isArray(sideListNode.content)) {
+			queryResult.sideList = parseNodeList(sideListNode.content)
 		}
 
-		//TODO: implement side list
-		//const sideListNode = getBinaryNodeChild(usyncNode, 'side_list')
 		return queryResult
 	}