fix(history-sync): serialise tcToken persistence + drop external doc reference

Addresses 4 PR #390 review findings (Codex P1 + Copilot ×3):

#1 Codex P1 (real, MAJOR) — `storeTcTokensFromHistorySync` fire-and-forget
   created a write race when multiple history-sync chunks arrived in parallel
   (common during reconnect/QR scan). The function does a non-atomic
   read-then-merge-then-write: chunk B could read `existing` before chunk A
   wrote, then commit later and overwrite chunk A's newer timestamp. Even
   worse, the merged `__index` write could drop JIDs added by the other
   chunk, leaving stale tcTokens and persistent 463 send errors.

   FIX: introduced `scheduleHistoryTcTokenSync()` — a module-scoped
   single-concurrency promise chain that sequentialises all calls in order.
   The chain swallows prior errors so a single failure can't stall future
   runs. Call site stays fire-and-forget so the `messaging-history.set`
   emit is still instant (which is the whole point of PR #389).

#2 Copilot (same root as #1) — already covered by the chain.

#3+#4 Copilot — code comments referenced
   `Downloads/InfiniteAPI-Inbound-Latency-Fix-Documentation.md` which is
   intentionally out-of-tree (user keeps it locally). Replaced the broken
   refs with self-contained explanations covering the same rationale —
   future maintainers no longer need an external file to understand the
   trade-offs.

Skipped: CodeRabbit nitpick to extract a `fireAndForgetMappingStore` helper
(stylistic, current explicit form makes the lid/pn argument order obvious to
reviewers — keeping it).

Tests: 35/35 suites, 824/824 still passing. Customizations untouched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

WAProto/WAProto.proto

@@ -1,7 +1,7 @@
 syntax = "proto3";
 package proto;
 
-/// WhatsApp Version: 2.3000.1038024963
+/// WhatsApp Version: 2.3000.1038164556
 
 message ADVDeviceIdentity {
     optional uint32 rawId = 1;

WAProto/fix-imports.js

@@ -18,14 +18,21 @@ try {
     '\tif (typeof value === "number") {\n' +
     '\t\treturn String(value);\n' +
     '\t}\n' +
-    '\tif (!$util.Long) {\n' +
-    '\t\treturn String(value);\n' +
+    '\t// Fast path: convert Long {low, high} directly via native BigInt\n' +
+    '\t// BigInt.toString() is a native C++ operation, much faster than Long\'s pure JS division loops\n' +
+    '\tif (value && typeof value.low === "number" && typeof value.high === "number") {\n' +
+    '\t\t// Normalize high to signed int32 so the sign-bit check works for inputs\n' +
+    '\t\t// where high is stored unsigned (e.g. raw {low, high} JSON).\n' +
+    '\t\tconst high = value.high | 0;\n' +
+    '\t\tconst lo = BigInt(value.low >>> 0);\n' +
+    '\t\tconst hi = BigInt(value.high >>> 0);\n' +
+    '\t\tconst combined = (hi << 32n) | lo;\n' +
+    '\t\tif (!unsigned && high < 0) {\n' +
+    '\t\t\treturn (combined - (1n << 64n)).toString();\n' +
+    '\t\t}\n' +
+    '\t\treturn combined.toString();\n' +
     '\t}\n' +
-    '\tconst normalized = $util.Long.fromValue(value);\n' +
-    '\tconst prepared = unsigned && normalized && typeof normalized.toUnsigned === "function"\n' +
-    '\t\t? normalized.toUnsigned()\n' +
-    '\t\t: normalized;\n' +
-    '\treturn prepared.toString();\n' +
+    '\treturn String(value);\n' +
     '}\n\n'
   const longToNumberHelper =
     'function longToNumber(value, unsigned) {\n' +
@@ -33,19 +40,20 @@ try {
     '\t\treturn value;\n' +
     '\t}\n' +
     '\tif (typeof value === "string") {\n' +
-    '\t\tconst numeric = Number(value);\n' +
-    '\t\treturn numeric;\n' +
-    '\t}\n' +
-    '\tif (!$util.Long) {\n' +
     '\t\treturn Number(value);\n' +
     '\t}\n' +
-    '\tconst normalized = $util.Long.fromValue(value);\n' +
-    '\tconst prepared = unsigned && normalized && typeof normalized.toUnsigned === "function"\n' +
-    '\t\t? normalized.toUnsigned()\n' +
-    '\t\t: typeof normalized.toSigned === "function"\n' +
-    '\t\t\t? normalized.toSigned()\n' +
-    '\t\t\t: normalized;\n' +
-    '\treturn prepared.toNumber();\n' +
+    '\t// Fast path: convert Long {low, high} directly via native BigInt\n' +
+    '\tif (value && typeof value.low === "number" && typeof value.high === "number") {\n' +
+    '\t\tconst high = value.high | 0;\n' +
+    '\t\tconst lo = BigInt(value.low >>> 0);\n' +
+    '\t\tconst hi = BigInt(value.high >>> 0);\n' +
+    '\t\tconst combined = (hi << 32n) | lo;\n' +
+    '\t\tif (!unsigned && high < 0) {\n' +
+    '\t\t\treturn Number(combined - (1n << 64n));\n' +
+    '\t\t}\n' +
+    '\t\treturn Number(combined);\n' +
+    '\t}\n' +
+    '\treturn Number(value);\n' +
     '}\n\n'
 
   if (!content.includes('function longToString(')) {

WAProto/index.js

@@ -12,14 +12,21 @@ function longToString(value, unsigned) {
 	if (typeof value === "number") {
 		return String(value);
 	}
-	if (!$util.Long) {
-		return String(value);
+	// Fast path: convert Long {low, high} directly via native BigInt
+	// BigInt.toString() is a native C++ operation, much faster than Long's pure JS division loops
+	if (value && typeof value.low === "number" && typeof value.high === "number") {
+		// Normalize high to signed int32 so the sign-bit check works for inputs
+		// where high is stored unsigned (e.g. raw {low, high} JSON).
+		const high = value.high | 0;
+		const lo = BigInt(value.low >>> 0);
+		const hi = BigInt(value.high >>> 0);
+		const combined = (hi << 32n) | lo;
+		if (!unsigned && high < 0) {
+			return (combined - (1n << 64n)).toString();
+		}
+		return combined.toString();
 	}
-	const normalized = $util.Long.fromValue(value);
-	const prepared = unsigned && normalized && typeof normalized.toUnsigned === "function"
-		? normalized.toUnsigned()
-		: normalized;
-	return prepared.toString();
+	return String(value);
 }
 
 function longToNumber(value, unsigned) {
@@ -27,19 +34,20 @@ function longToNumber(value, unsigned) {
 		return value;
 	}
 	if (typeof value === "string") {
-		const numeric = Number(value);
-		return numeric;
-	}
-	if (!$util.Long) {
 		return Number(value);
 	}
-	const normalized = $util.Long.fromValue(value);
-	const prepared = unsigned && normalized && typeof normalized.toUnsigned === "function"
-		? normalized.toUnsigned()
-		: typeof normalized.toSigned === "function"
-			? normalized.toSigned()
-			: normalized;
-	return prepared.toNumber();
+	// Fast path: convert Long {low, high} directly via native BigInt
+	if (value && typeof value.low === "number" && typeof value.high === "number") {
+		const high = value.high | 0;
+		const lo = BigInt(value.low >>> 0);
+		const hi = BigInt(value.high >>> 0);
+		const combined = (hi << 32n) | lo;
+		if (!unsigned && high < 0) {
+			return Number(combined - (1n << 64n));
+		}
+		return Number(combined);
+	}
+	return Number(value);
 }
 
 export const proto = $root.proto = (() => {

src/Defaults/baileys-version.json

@@ -1 +1 @@
-{"version":[2,3000,1038147544]}
+{"version":[2,3000,1038167900]}

src/Socket/chats.ts

@@ -98,6 +98,24 @@ export const makeChatsSocket = (config: SocketConfig) => {
 
 	let privacySettings: { [_: string]: string } | undefined
 
+	/**
+	 * Server-assigned AB props that gate tctoken-related protocol behavior.
+	 * Defaults match WA Web (safe — avoids spurious error 463 if the prop never
+	 * arrives). Populated from `fetchProps()` on connection.
+	 *
+	 * - `privacyTokenOn1to1` (AB prop 10518 / `privacy_token_sending_on_all_1_on_1_messages`):
+	 *    include tctoken in 1:1 messages.
+	 * - `profilePicPrivacyToken` (AB prop 9666 / `profile_scraping_privacy_token_in_photo_iq`):
+	 *    include tctoken in profile picture IQs.
+	 * - `lidTrustedTokenIssueToLid` (AB prop 14303 / `lid_trusted_token_issue_to_lid`):
+	 *    issue privacy tokens to the contact's LID instead of the PN.
+	 */
+	const serverProps = {
+		privacyTokenOn1to1: true,
+		profilePicPrivacyToken: true,
+		lidTrustedTokenIssueToLid: false
+	}
+
 	let syncState: SyncState = SyncState.Connecting
 
 	/** this mutex ensures that messages from the same chat are processed in order, while allowing parallel processing of messages from different chats */
@@ -791,7 +809,10 @@ export const makeChatsSocket = (config: SocketConfig) => {
 			me && (normalizedJid === jidNormalizedUser(me.id) || (me.lid && normalizedJid === jidNormalizedUser(me.lid)))
 		let content: BinaryNode[] | undefined = baseContent
 
-		if (isUserJid && !isSelf) {
+		// Gate inclusion on AB prop 9666 (profile_scraping_privacy_token_in_photo_iq).
+		// WA Web defaults to true; if the server flips it off, we mirror that to
+		// avoid divergence with the spec-compliant client.
+		if (serverProps.profilePicPrivacyToken && isUserJid && !isSelf) {
 			content = await buildTcTokenFromJid({
 				authState,
 				jid: normalizedJid,
@@ -1093,7 +1114,25 @@ export const makeChatsSocket = (config: SocketConfig) => {
 			props = reduceBinaryNodeToDictionary(propsNode, 'prop')
 		}
 
-		logger.debug('fetched props')
+		// Extract protocol-relevant AB props (defaults match WA Web; see serverProps doc).
+		// We accept both numeric IDs and human-readable names so the parser is resilient
+		// to upstream renaming and to future-versioned WA Web servers.
+		const privacyTokenProp = props['10518'] ?? props['privacy_token_sending_on_all_1_on_1_messages']
+		if (privacyTokenProp !== undefined) {
+			serverProps.privacyTokenOn1to1 = privacyTokenProp === 'true' || privacyTokenProp === '1'
+		}
+
+		const profilePicProp = props['9666'] ?? props['profile_scraping_privacy_token_in_photo_iq']
+		if (profilePicProp !== undefined) {
+			serverProps.profilePicPrivacyToken = profilePicProp === 'true' || profilePicProp === '1'
+		}
+
+		const lidIssueProp = props['14303'] ?? props['lid_trusted_token_issue_to_lid']
+		if (lidIssueProp !== undefined) {
+			serverProps.lidTrustedTokenIssueToLid = lidIssueProp === 'true' || lidIssueProp === '1'
+		}
+
+		logger.debug({ serverProps }, 'fetched props')
 
 		return props
 	}
@@ -1611,6 +1650,7 @@ export const makeChatsSocket = (config: SocketConfig) => {
 
 	return {
 		...sock,
+		serverProps,
 		createCallLink,
 		getBotListV2,
 		messageMutex,

src/Socket/messages-recv.ts

@@ -73,7 +73,14 @@ import {
 	recordMessageReceived,
 	recordMessageRetry
 } from '../Utils/prometheus-metrics.js'
-import { isTcTokenExpired, resolveTcTokenJid, storeTcTokensFromIqResult } from '../Utils/tc-token-utils'
+import {
+	buildMergedTcTokenIndexWrite,
+	isTcTokenExpired,
+	resolveIssuanceJid,
+	resolveTcTokenJid,
+	storeTcTokensFromIqResult,
+	TC_TOKEN_INDEX_KEY
+} from '../Utils/tc-token-utils'
 import {
 	areJidsSameUser,
 	type BinaryNode,
@@ -164,7 +171,12 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 	let sendActiveReceipts = false
 
 	// ======= tctoken index tracking for cross-session pruning =======
-	const TC_TOKEN_INDEX_KEY = '__index'
+	// TC_TOKEN_INDEX_KEY is imported from tc-token-utils so the value stays in sync
+	// with messages-send/process-message writes (avoids string drift on rename).
+	// Race note: this prune-driven index write may interleave with
+	// buildMergedTcTokenIndexWrite calls from issuance/history-sync paths. Worst
+	// case: a JID resurrected by a stale read gets pruned again on the next 24h
+	// sweep — no data loss, just one extra cycle.
 	const TC_TOKEN_PRUNE_TS_KEY = '__prune_ts'
 	const tcTokenKnownJids = new Set<string>()
 	const tcTokenRetriedMsgIds = new Set<string>()
@@ -198,16 +210,25 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		}
 	})()
 
-	/** Debounced save of the tctoken JID index (5s) */
+	/**
+	 * Debounced save of the tctoken JID index (5s).
+	 *
+	 * Merges with the persisted index instead of overwriting — other layers
+	 * (messages-send fire-and-forget issuance, process-message history sync) may
+	 * write JIDs to the index via `buildMergedTcTokenIndexWrite` without updating
+	 * `tcTokenKnownJids`. Without the merge those JIDs would be silently dropped
+	 * the next time this debounced save fires.
+	 */
 	const scheduleTcTokenIndexSave = () => {
 		if (tcTokenIndexSaveTimer) clearTimeout(tcTokenIndexSaveTimer)
 		tcTokenIndexSaveTimer = setTimeout(async () => {
 			try {
-				const arr = Array.from(tcTokenKnownJids)
+				const merged = await buildMergedTcTokenIndexWrite(authState.keys, tcTokenKnownJids)
 				await authState.keys.set({
 					tctoken: {
+						...merged,
 						[TC_TOKEN_INDEX_KEY]: {
-							token: Buffer.from(JSON.stringify(arr), 'utf8'),
+							...merged[TC_TOKEN_INDEX_KEY],
 							timestamp: unixTimestampSeconds().toString()
 						}
 					}
@@ -1434,6 +1455,58 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		}, authState?.creds?.me?.id || 'sendRetryRequest')
 	}
 
+	/**
+	 * Fire-and-forget tctoken re-issuance after a peer's device identity changed.
+	 * Mirrors WAWebSendTcTokenWhenDeviceIdentityChange — runs in PARALLEL with the
+	 * session refresh (not after it).
+	 *
+	 * Why parallel and not sequential:
+	 *  - WA Web invokes this BEFORE assertSessions to maximise the chance the contact
+	 *    has a fresh tctoken by the time the next outbound send executes.
+	 *  - Running after assertSessions (the fork's previous behaviour) races with the
+	 *    next send and risks error 463 when the contact reinstalls and the user replies
+	 *    immediately afterwards.
+	 *
+	 * Gated on `entry.senderTimestamp` (we previously issued a token to this peer in the
+	 * current bucket window). Preserves the existing senderTimestamp instead of issuing
+	 * a fresh one — keeps WA Web's bucket coalescing semantics: same token, same window.
+	 */
+	const reissueTcTokenAfterIdentityChange = (from: string): void => {
+		void (async () => {
+			const normalizedJid = jidNormalizedUser(from)
+			const tcJid = await resolveTcTokenJid(normalizedJid, getLIDForPN)
+			const tcTokenData = await authState.keys.get('tctoken', [tcJid])
+			const senderTs = tcTokenData?.[tcJid]?.senderTimestamp
+
+			if (senderTs === null || senderTs === undefined || isTcTokenExpired(senderTs)) {
+				return
+			}
+
+			logTcToken('reissue', { jid: normalizedJid, reason: 'identity_changed', senderTimestamp: senderTs })
+			const getPNForLID = signalRepository.lidMapping.getPNForLID.bind(signalRepository.lidMapping)
+			const issueJid = await resolveIssuanceJid(
+				normalizedJid,
+				sock.serverProps.lidTrustedTokenIssueToLid,
+				getLIDForPN,
+				getPNForLID
+			)
+			const result = await getPrivacyTokens([issueJid], senderTs)
+			await storeTcTokensFromIqResult({
+				result,
+				fallbackJid: tcJid,
+				keys: authState.keys,
+				getLIDForPN,
+				onNewJidStored: storedJid => {
+					tcTokenKnownJids.add(storedJid)
+					scheduleTcTokenIndexSave()
+				}
+			})
+			logTcToken('reissue_ok', { jid: normalizedJid, reason: 'identity_changed' })
+		})().catch(err => {
+			logTcToken('reissue_fail', { jid: from, error: err?.message })
+		})
+	}
+
 	const handleEncryptNotification = async (node: BinaryNode) => {
 		const from = node.attrs.from
 		if (from === S_WHATSAPP_NET) {
@@ -1453,57 +1526,12 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 				validateSession: signalRepository.validateSession,
 				assertSessions,
 				debounceCache: identityAssertDebounce,
-				logger
+				logger,
+				// Fire reissue in parallel with the session refresh, NOT after it.
+				// See reissueTcTokenAfterIdentityChange doc for the rationale.
+				onBeforeSessionRefresh: reissueTcTokenAfterIdentityChange
 			})
 
-			// When a session is refreshed (identity change), re-issue tctoken fire-and-forget
-			// WABA Android: reissue stores senderTimestamp + realIssueTimestamp after IQ success
-			if (result.action === 'session_refreshed') {
-				const normalizedJid = jidNormalizedUser(from)
-				resolveTcTokenJid(normalizedJid, getLIDForPN)
-					.then(async tcJid => {
-						const tcData = await authState.keys.get('tctoken', [tcJid])
-						const entry = tcData[tcJid]
-						if (entry?.token?.length && !isTcTokenExpired(entry.timestamp)) {
-							const senderTs = unixTimestampSeconds()
-							logTcToken('reissue', { jid: normalizedJid, reason: 'session_refreshed' })
-							getPrivacyTokens([normalizedJid], senderTs)
-								.then(async (iqResult) => {
-									await storeTcTokensFromIqResult({
-										result: iqResult,
-										fallbackJid: normalizedJid,
-										keys: authState.keys,
-										getLIDForPN,
-										onNewJidStored: (storedJid) => {
-											tcTokenKnownJids.add(storedJid)
-											scheduleTcTokenIndexSave()
-										}
-									})
-									// Persist senderTimestamp + realIssueTimestamp after IQ success
-									const currentData = await authState.keys.get('tctoken', [tcJid])
-									const currentEntry = currentData[tcJid]
-									await authState.keys.set({
-										tctoken: {
-											[tcJid]: {
-												...currentEntry,
-												token: currentEntry?.token ?? Buffer.alloc(0),
-												senderTimestamp: senderTs,
-												realIssueTimestamp: 0
-											}
-										}
-									})
-									logTcToken('reissue_ok', { jid: normalizedJid, reason: 'session_refreshed' })
-								})
-								.catch(err => {
-									logTcToken('reissue_fail', { jid: normalizedJid, error: err?.message })
-								})
-						}
-					})
-					.catch(() => {
-						/* ignore resolution errors */
-					})
-			}
-
 			if (result.action === 'no_identity_node') {
 				logger.info({ node }, 'unknown encrypt notification')
 			}
@@ -2302,44 +2330,54 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		)
 
 		const alt = msg.key.participantAlt || msg.key.remoteJidAlt
-		// Handle LID/PN mappings with hybrid approach:
-		// - Store mapping operation runs in background (non-critical for decrypt)
-		// - Session migration MUST complete before decrypt() to avoid "No session record" errors
-		// This addresses Codex/Copilot review concerns about race conditions with decrypt()
+		// Handle LID/PN mappings with optimized hot-path:
+		// - storeLIDPNMappings is fire-and-forget (background) — does NOT block decrypt
+		// - migrateSession is SYNC (await) — REQUIRED for decrypt to find session
+		//
+		// SAFETY: normalizeMessageJids has a fast-path that uses key.*Alt directly without
+		// hitting the store, so the just-arrived message normalizes correctly even before
+		// the background store completes. Subsequent messages in the same chat hit the
+		// store after the background write is done (ms later).
+		//
+		// Pre-check (getPNForLID/getLIDForPN) was removed — storeLIDPNMappings has internal
+		// LRU cache + dedup, the pre-check was a redundant store round-trip per inbound
+		// message that added latency under load.
+		//
+		// HISTORICAL: this restores the intent of d73cd28d39 (2026-02-03) which was
+		// partially reverted by c3fc792351 the same day due to a race-condition concern
+		// with migrateSession (kept sync here). storeLIDPNMappings was over-protected:
+		// it persists a mapping that downstream consumers can re-derive from key.*Alt,
+		// while migrateSession actually moves the Signal session record that decrypt()
+		// will load microseconds later — those two have very different criticality.
+		//
+		// DO NOT make migrateSession async — decrypt() depends on the session being at
+		// the correct identifier (LID vs PN) when it runs. Other code paths (USync
+		// device lookup in messages-send.ts) create LID/PN mappings without migrating
+		// the session, so we cannot skip migration even when the mapping already exists.
 		if (!!alt) {
 			const altServer = jidDecode(alt)?.server
 			const primaryJid = msg.key.participant || msg.key.remoteJid!
 
 			if (altServer === 'lid') {
-				// Check if mapping already exists to avoid unnecessary storage operations
-				const existingMapping = await signalRepository.lidMapping.getPNForLID(alt)
-				if (!existingMapping) {
-					// MUST await: normalizeMessageJids() runs after this and needs the mapping
-					// in the LIDMappingStore to resolve LID→PN for events delivered to consumers
-					await signalRepository.lidMapping
-						.storeLIDPNMappings([{ lid: alt, pn: primaryJid }])
-						.catch(error => logger.warn({ error, alt, primaryJid }, 'LID mapping storage failed'))
-				}
+				// Fire-and-forget: storeLIDPNMappings has internal cache+dedup,
+				// pre-check (getPNForLID) was redundant.
+				signalRepository.lidMapping
+					.storeLIDPNMappings([{ lid: alt, pn: primaryJid }])
+					.catch(error => logger.warn({ error, alt, primaryJid }, 'background LID mapping store failed'))
 
-				// CRITICAL: ALWAYS migrate session, even if mapping exists
-				// Other code paths (e.g., USync device lookup in messages-send.ts:310-319)
-				// may create mappings via storeLIDPNMappings() without calling migrateSession()
-				// This leaves sessions under PN format while decrypt() expects LID format
-				// Skipping migration based on mapping existence causes "No session record" errors
+				// CRITICAL: ALWAYS migrate session SYNC, even if mapping exists.
+				// Other code paths (e.g., USync device lookup in messages-send.ts) may create
+				// mappings via storeLIDPNMappings() without calling migrateSession(). This
+				// leaves sessions under PN format while decrypt() expects LID format.
+				// Skipping migration based on mapping existence causes "No session record" errors.
 				await signalRepository.migrateSession(primaryJid, alt)
 			} else {
-				// Check if reverse mapping exists
-				const existingMapping = await signalRepository.lidMapping.getLIDForPN(alt)
-				if (!existingMapping) {
-					// MUST await: normalizeMessageJids() runs after this and needs the mapping
-					// in the LIDMappingStore to resolve LID→PN for events delivered to consumers
-					await signalRepository.lidMapping
-						.storeLIDPNMappings([{ lid: primaryJid, pn: alt }])
-						.catch(error => logger.warn({ error, alt, primaryJid }, 'LID mapping storage failed'))
-				}
+				// Fire-and-forget: same rationale as above.
+				signalRepository.lidMapping
+					.storeLIDPNMappings([{ lid: primaryJid, pn: alt }])
+					.catch(error => logger.warn({ error, alt, primaryJid }, 'background LID mapping store failed'))
 
-				// CRITICAL: ALWAYS migrate session, even if mapping exists
-				// Same reasoning as above - mapping existence doesn't guarantee session migration
+				// CRITICAL: ALWAYS migrate session SYNC.
 				await signalRepository.migrateSession(alt, primaryJid)
 			}
 		}
@@ -3220,19 +3258,24 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 			// Await index load first — prevents overwriting a more complete persisted index
 			// if the connection closes before the initial load finishes.
 			tcTokenIndexLoaded
-				.then(() => {
-					Promise.resolve(
-						authState.keys.set({
+				.then(async () => {
+					try {
+						// Same merge-with-persisted invariant as scheduleTcTokenIndexSave —
+						// other layers may have written cross-layer JIDs to the index since
+						// our in-memory set was last updated.
+						const merged = await buildMergedTcTokenIndexWrite(authState.keys, tcTokenKnownJids)
+						await authState.keys.set({
 							tctoken: {
+								...merged,
 								[TC_TOKEN_INDEX_KEY]: {
-									token: Buffer.from(JSON.stringify([...tcTokenKnownJids]), 'utf8'),
+									...merged[TC_TOKEN_INDEX_KEY],
 									timestamp: unixTimestampSeconds().toString()
 								}
 							}
 						})
-					).catch(() => {
+					} catch {
 						/* non-critical */
-					})
+					}
 				})
 				.catch(() => {
 					/* non-critical */

src/Socket/messages-send.ts

@@ -46,7 +46,10 @@ import { makeKeyedMutex } from '../Utils/make-mutex'
 import { metrics, recordMessageFailure, recordMessageSent } from '../Utils/prometheus-metrics'
 import { getMessageReportingToken, shouldIncludeReportingToken } from '../Utils/reporting-utils'
 import {
+	buildMergedTcTokenIndexWrite,
+	isRegularUser,
 	isTcTokenExpired,
+	resolveIssuanceJid,
 	resolveTcTokenJid,
 	shouldSendNewTcToken,
 	storeTcTokensFromIqResult
@@ -125,6 +128,15 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 	// Tracks JIDs with an in-flight getPrivacyTokens IQ to avoid duplicate concurrent fetches
 	const tcTokenFetchingJids = new Set<string>()
 
+	/**
+	 * Set of tctoken storage JIDs with a fire-and-forget `issuePrivacyTokens` IQ in flight.
+	 * Distinct from `tcTokenFetchingJids` (which dedupes inbound *fetches* of the peer's
+	 * token). Prevents duplicate IQs when a caller fires several rapid back-to-back sends
+	 * to the same contact before `senderTimestamp` persists. Entries are always removed
+	 * in `.finally()`, so the set is bounded by current concurrency.
+	 */
+	const inFlightTcTokenIssuance = new Set<string>()
+
 	let mediaConn: Promise<MediaConnInfo>
 	const refreshMediaConn = async (forceGet = false) => {
 		const media = await mediaConn
@@ -1715,7 +1727,16 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 				}
 			}
 
-			if (tcTokenBuffer?.length) {
+			// Gate inclusion on AB prop 10518 (privacy_token_sending_on_all_1_on_1_messages).
+			// WA Web defaults to true; if the server flips it off we mirror that to avoid
+			// divergence with the spec-compliant client.
+			//
+			// CARROUSEL EXCEPTION: Pastorini-validated carousel stanzas REQUIRE tctoken
+			// (CDP capture confirms it). If the AB prop ever flips off, dropping the
+			// tctoken from carousel would break rendering on Android. Carousel always
+			// includes the tctoken when one is available, regardless of the prop —
+			// matching the fork's existing behaviour pre-PR #2339.
+			if (tcTokenBuffer?.length && (sock.serverProps.privacyTokenOn1to1 || isCarousel)) {
 				;(stanza.content as BinaryNode[]).push({
 					tag: 'tctoken',
 					attrs: {},
@@ -1815,13 +1836,39 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 			// Gated only by shouldSendNewTcToken — removed tcTokenBuffer?.length guard so
 			// issuance fires even when we don't yet hold a token (bucket boundary crossed).
 			// IMPORTANT: must run AFTER sendNode — issuing before the message causes error 463.
-			if (is1on1Send && shouldSendNewTcToken(existingTokenEntry?.senderTimestamp)) {
+			//
+			// WA Web also skips issuance for:
+			//   - protocol messages (revoke, ephemeral settings, etc — see TcTokenChatAction)
+			//   - PSA, bots, MetaAI (isRegularUser filter)
+			// and dedupes back-to-back issuances with `inFlightTcTokenIssuance` so a burst of
+			// rapid sends to the same contact only triggers a single IQ before senderTimestamp
+			// is persisted.
+			const isProtocolMsg = !!normalizeMessageContent(message)?.protocolMessage
+			// Use isRegularUser (the same Wid.isRegularUser() port that gates the store
+			// path) so we filter PSA/bot/MetaAI consistently regardless of JID server
+			// (@c.us vs @s.whatsapp.net) and device suffix. The previous PSA_WID/isJidBot
+			// checks only matched @c.us forms — destinationJid arrives normalized.
+			const isBotOrPSA = !isRegularUser(destinationJid)
+			if (
+				is1on1Send &&
+				!isProtocolMsg &&
+				!isBotOrPSA &&
+				shouldSendNewTcToken(existingTokenEntry?.senderTimestamp) &&
+				!inFlightTcTokenIssuance.has(tcTokenJid)
+			) {
+				inFlightTcTokenIssuance.add(tcTokenJid)
 				const issueTimestamp = unixTimestampSeconds()
 				logTcToken('reissue', { jid: destinationJid })
-				getPrivacyTokens([destinationJid], issueTimestamp)
+				const getPNForLID = signalRepository.lidMapping.getPNForLID.bind(signalRepository.lidMapping)
+				resolveIssuanceJid(
+					destinationJid,
+					sock.serverProps.lidTrustedTokenIssueToLid,
+					getLIDForPN,
+					getPNForLID
+				)
+					.then(issueJid => getPrivacyTokens([issueJid], issueTimestamp))
 					.then(async result => {
 						// Store any tokens received in the IQ response.
-						// onNewJidStored not passed — pruning index lives in messages-recv (higher layer).
 						await storeTcTokensFromIqResult({
 							result,
 							fallbackJid: tcTokenJid,
@@ -1832,9 +1879,11 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 						// Persist senderTimestamp unconditionally — WA Web stores it in the chat table
 						// regardless of whether a token exists. Spread preserves token+timestamp if present.
 						// WABA Android: INSERT INTO wa_trusted_contacts_send (jid, sent_tc_token_timestamp, real_issue_timestamp)
-						// VALUES (?, ?, 0) — realIssueTimestamp=0 means issued but not yet confirmed by server
+						// VALUES (?, ?, 0) — realIssueTimestamp=0 means issued but not yet confirmed by server.
+						// Also bump the cross-session prune index so this JID is tracked persistently.
 						const currentData = await authState.keys.get('tctoken', [tcTokenJid])
 						const currentEntry = currentData[tcTokenJid]
+						const indexWrite = await buildMergedTcTokenIndexWrite(authState.keys, [tcTokenJid])
 						await authState.keys.set({
 							tctoken: {
 								[tcTokenJid]: {
@@ -1842,7 +1891,8 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 									token: currentEntry?.token ?? Buffer.alloc(0),
 									senderTimestamp: issueTimestamp,
 									realIssueTimestamp: 0
-								}
+								},
+								...indexWrite
 							}
 						})
 
@@ -1851,6 +1901,9 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 					.catch(err => {
 						logTcToken('reissue_fail', { jid: destinationJid, error: err?.message })
 					})
+					.finally(() => {
+						inFlightTcTokenIssuance.delete(tcTokenJid)
+					})
 			}
 
 			// Log with [BAILEYS] prefix

src/Utils/history.ts

@@ -1,5 +1,6 @@
+import { pipeline } from 'stream/promises'
 import { promisify } from 'util'
-import { inflate } from 'zlib'
+import { createInflate, inflate } from 'zlib'
 import { proto } from '../../WAProto/index.js'
 import type { Chat, Contact, LIDMapping, WAMessage } from '../Types'
 import { WAMessageStubType } from '../Types'
@@ -29,16 +30,15 @@ const inflatePromise = promisify(inflate)
  */
 export const downloadHistory = async (msg: proto.Message.IHistorySyncNotification, options: RequestInit) => {
 	const stream = await downloadContentFromMessage(msg, 'md-msg-hist', { options })
-	const bufferArray: Buffer[] = []
-	for await (const chunk of stream) {
-		bufferArray.push(chunk)
-	}
-
-	let buffer: Buffer = Buffer.concat(bufferArray)
-
-	// decompress buffer
-	buffer = await inflatePromise(buffer)
+	// Pipe decrypted stream directly through zlib inflate.
+	// Avoids allocating an intermediate buffer for the compressed payload —
+	// memory peaks during 50MB history syncs drop ~50% (PR upstream #2333).
+	const inflater = createInflate()
+	const chunks: Buffer[] = []
+	inflater.on('data', (chunk: Buffer) => chunks.push(chunk))
+	await pipeline(stream, inflater)
 
+	const buffer = Buffer.concat(chunks)
 	const syncData = proto.HistorySync.decode(buffer)
 	return syncData
 }
@@ -361,7 +361,7 @@ export const processHistoryMessage = (item: proto.IHistorySync, logger?: ILogger
 					}
 				}
 
-				chats.push({ ...chat })
+				chats.push(chat)
 			}
 
 			break

src/Utils/identity-change-handler.ts

@@ -57,6 +57,16 @@ export type IdentityChangeContext = {
 	debounceCache: NodeCache<boolean>
 	/** Logger instance for debugging and monitoring */
 	logger: ILogger
+	/**
+	 * Invoked right before `assertSessions` is called for an existing-session identity
+	 * change. Used to kick off fire-and-forget side effects (e.g. tctoken re-issuance)
+	 * in the same order WA Web does — i.e. before the E2E session is re-established.
+	 * Must not throw; implementations are responsible for their own error handling.
+	 *
+	 * Skipped when the refresh itself is skipped (no_identity_node, invalid_notification,
+	 * skipped_companion_device, skipped_self_primary, debounced, skipped_offline).
+	 */
+	onBeforeSessionRefresh?: (jid: string) => void
 }
 
 // ============================================================================
@@ -170,6 +180,19 @@ export async function handleIdentityChange(
 	// This ensures we don't incorrectly debounce when we exit early (offline, etc.)
 	ctx.debounceCache.set(from, true)
 
+	// Fire-and-forget side effects (e.g. tctoken re-issuance) BEFORE the session is
+	// re-established. WA Web runs these in parallel with the session refresh —
+	// running afterwards would race with the next outbound send and risk error 463.
+	//
+	// Wrapped in try/catch so a misbehaving consumer callback cannot abort identity
+	// change recovery. We log and continue — assertSessions still runs so the E2E
+	// session always gets refreshed.
+	try {
+		ctx.onBeforeSessionRefresh?.(from)
+	} catch (error) {
+		ctx.logger.warn({ error, jid: from }, 'onBeforeSessionRefresh callback threw — continuing with session refresh')
+	}
+
 	// Attempt session refresh/creation
 	try {
 		await ctx.assertSessions([from], true)

src/Utils/messages-media.ts

@@ -618,7 +618,7 @@ export const downloadEncryptedContent = async (
 
 	const output = new Transform({
 		transform(chunk, _, callback) {
-			let data = Buffer.concat([remainingBytes, chunk])
+			let data = remainingBytes.length ? Buffer.concat([remainingBytes, chunk]) : chunk
 
 			const decryptLength = toSmallestChunkSize(data.length)
 			remainingBytes = data.slice(decryptLength)

src/Utils/process-message.ts

@@ -40,6 +40,7 @@ import { getKeyAuthor, toNumber } from './generics'
 import { downloadAndProcessHistorySyncNotification } from './history'
 import type { ILogger } from './logger'
 import { metrics, recordHistorySyncMessages } from './prometheus-metrics.js'
+import { buildMergedTcTokenIndexWrite } from './tc-token-utils'
 
 type ProcessMessageContext = {
 	shouldProcessHistoryMsg: boolean
@@ -62,6 +63,163 @@ const REAL_MSG_STUB_TYPES = new Set([
 
 const REAL_MSG_REQ_ME_STUB_TYPES = new Set([WAMessageStubType.GROUP_PARTICIPANT_ADD])
 
+/**
+ * Extract tctoken / tcTokenTimestamp / tcTokenSenderTimestamp from history-sync chats
+ * and persist them to the `tctoken` store. Mirrors WA Web's `bulkCreateOrMerge` pass
+ * over the chat table during history sync.
+ *
+ * Why this matters: when a user logs in on a new device, the multi-device history sync
+ * is the only way that device learns about tctokens issued/received on the original
+ * device. Without this pass, the new device sends 1:1 messages with no tctoken until
+ * the contact triggers a fresh notification — which surfaces as error 463 in production.
+ *
+ * Monotonicity: we only overwrite an existing entry if the incoming timestamp is
+ * STRICTLY newer (`incoming > existing`). Equal timestamps are skipped to avoid
+ * reverting senderTimestamp / realIssueTimestamp set by other layers (e.g. a
+ * reissue that fired between history-sync chunks).
+ *
+ * Index hygiene: every JID we write here is added to the persistent prune index
+ * (TC_TOKEN_INDEX_KEY) via buildMergedTcTokenIndexWrite, so the 24h prune sweep in
+ * messages-recv picks them up across sessions.
+ */
+/**
+ * Single-concurrency queue for `storeTcTokensFromHistorySync` calls.
+ *
+ * Why: the function does read-then-write merges (`keyStore.get('tctoken', ...)` →
+ * compute → `keyStore.set(...)`) which are NOT atomic at the store level. If two
+ * history-sync chunks invoke this concurrently (common during reconnect / QR
+ * scan), an older chunk that started first can `keyStore.set` AFTER a newer
+ * chunk, overwriting the newer entry — and worse, the merged `__index` write
+ * can drop JIDs the other chunk just added. Result: stale tcTokens / repeat 463
+ * sends until the next opportunistic refetch.
+ *
+ * Serialising via a chained Promise keeps the runs ordered while still freeing
+ * the calling `processMessage` to emit `messaging-history.set` immediately
+ * (the chain is fire-and-forget at the call site). Errors don't break the chain
+ * — each `catch` resets it to `Promise.resolve()` so a single failure can't
+ * stall future runs.
+ *
+ * The chain is module-scoped (one per Node process). Multiple Baileys instances
+ * sharing this module will serialise across instances too, but their writes
+ * target different keyStores so there's no correctness gain — only a tiny loss
+ * of inter-instance parallelism for tcToken syncs, which is acceptable given
+ * how rarely this runs vs. how rare cross-instance contention is.
+ */
+let historyTcTokenChain: Promise<void> = Promise.resolve()
+
+function scheduleHistoryTcTokenSync(
+	chats: Chat[],
+	signalRepository: SignalRepositoryWithLIDStore,
+	keyStore: SignalKeyStoreWithTransaction,
+	logger?: ILogger
+): void {
+	historyTcTokenChain = historyTcTokenChain
+		.catch(() => {
+			/* swallow prior error so chain stays alive */
+		})
+		.then(() => storeTcTokensFromHistorySync(chats, signalRepository, keyStore, logger))
+		.catch(err => {
+			logger?.warn({ err }, 'background tctoken history-sync persistence failed')
+		})
+}
+
+async function storeTcTokensFromHistorySync(
+	chats: Chat[],
+	signalRepository: SignalRepositoryWithLIDStore,
+	keyStore: SignalKeyStoreWithTransaction,
+	logger?: ILogger
+) {
+	// Cheap filter first — most chats in a sync chunk don't carry tcToken at all,
+	// and we want to avoid spinning up promises for them.
+	const tokenChats = chats.filter(chat => {
+		const ts = chat.tcTokenTimestamp ? toNumber(chat.tcTokenTimestamp) : 0
+		return !!chat.tcToken?.length && ts > 0
+	})
+
+	if (!tokenChats.length) {
+		return
+	}
+
+	// Pre-normalize so the rest of the pipeline is a synchronous join.
+	const normalized = tokenChats.map(chat => ({
+		chat,
+		ts: toNumber(chat.tcTokenTimestamp!),
+		jid: jidNormalizedUser(chat.id!)
+	}))
+
+	// BATCHED LID resolution. The previous shape called getLIDForPN once per
+	// chat (sequential await inside a for-of), which became the bottleneck
+	// during heavy history sync — every cold-cache hit was a DB round-trip,
+	// stalling messaging-history.set and spilling into the event-buffer.
+	// `getLIDsForPNs` resolves a deduped list in ONE batched query (and shares
+	// USync retry across PNs that miss cache), turning O(N) round-trips into 1.
+	//
+	// LID inputs (and `@hosted.lid`) skip the lookup entirely — they're already
+	// the storage form. Failures degrade gracefully: a missing mapping just
+	// stores under the original jid, matching `resolveTcTokenJid`'s null branch.
+	const pnsToResolve = [...new Set(normalized.filter(({ jid }) => !isLidUser(jid)).map(({ jid }) => jid))]
+	const pnToLid = new Map<string, string>()
+
+	if (pnsToResolve.length) {
+		try {
+			const mappings = await signalRepository.lidMapping.getLIDsForPNs(pnsToResolve)
+			// Flat loop (continue-on-skip) keeps max nesting depth at 4 for lint.
+			for (const { pn, lid } of mappings ?? []) {
+				if (!pn || !lid) continue
+				pnToLid.set(jidNormalizedUser(pn), lid)
+			}
+		} catch (err) {
+			// Per-chat fallback below (storageJid := jid). Don't abort the chunk —
+			// CodeRabbit noted that all-or-nothing rejection here would drop every
+			// tctoken in the batch AND prevent messaging-history.set from firing.
+			logger?.warn({ err }, 'storeTcTokensFromHistorySync: getLIDsForPNs batch failed; falling back to per-chat jid')
+		}
+	}
+
+	const candidates = normalized.map(({ chat, ts, jid }) => ({
+		storageJid: pnToLid.get(jid) ?? jid,
+		token: Buffer.from(chat.tcToken!),
+		ts,
+		senderTs: chat.tcTokenSenderTimestamp ? toNumber(chat.tcTokenSenderTimestamp) : undefined
+	}))
+
+	const jids = candidates.map(c => c.storageJid)
+	const existing = await keyStore.get('tctoken', jids)
+	const entries: Record<string, { token: Buffer; timestamp?: string; senderTimestamp?: number }> = {}
+
+	for (const c of candidates) {
+		// Same-batch dedup: when two chats resolve to the same storageJid (e.g. PN+LID
+		// aliases collapsing through resolveTcTokenJid, or duplicate chunks across
+		// retries), prefer the value already written by an earlier iteration so a
+		// lower-ts entry can't overwrite a higher-ts one captured from `existing`.
+		const existingEntry = entries[c.storageJid] ?? existing[c.storageJid]
+		const existingTs = existingEntry?.timestamp ? Number(existingEntry.timestamp) : 0
+		// Strict > guard: equal timestamps are skipped so we never clobber
+		// senderTimestamp written by other layers (issuance after send, etc).
+		if (existingTs > 0 && existingTs >= c.ts) {
+			continue
+		}
+
+		entries[c.storageJid] = {
+			...existingEntry,
+			token: c.token,
+			timestamp: String(c.ts),
+			...(c.senderTs !== undefined ? { senderTimestamp: c.senderTs } : {})
+		}
+	}
+
+	if (Object.keys(entries).length) {
+		logger?.debug({ count: Object.keys(entries).length }, 'storing tctokens from history sync')
+		try {
+			// Include updated __index so cross-session pruning picks these JIDs up.
+			const indexWrite = await buildMergedTcTokenIndexWrite(keyStore, Object.keys(entries))
+			await keyStore.set({ tctoken: { ...entries, ...indexWrite } })
+		} catch (err) {
+			logger?.warn({ err }, 'failed to store tctokens from history sync')
+		}
+	}
+}
+
 /** Cleans a received message to further processing */
 export const cleanMessage = (message: WAMessage, meId: string, meLid: string) => {
 	// ensure remoteJid and participant doesn't have device or agent in it
@@ -418,6 +576,12 @@ const processMessage = async (
 
 					// Emit LID-PN mappings from history sync
 					// This is how WhatsApp Web learns mappings for chats with non-contacts
+					//
+					// MUST run BEFORE storeTcTokensFromHistorySync — otherwise resolveTcTokenJid()
+					// can't resolve PN→LID for fresh-device chats (mapping cache is empty), tokens
+					// get persisted under PN keys, and the send path (which resolves to LID first)
+					// misses them — exactly the error 463 scenario this whole change is meant to
+					// prevent. Catches Codex P1 review on PR #386.
 					if (data.lidPnMappings?.length) {
 						logger?.debug({ count: data.lidPnMappings.length }, 'processing LID-PN mappings from history sync')
 						// eslint-disable-next-line max-depth
@@ -442,6 +606,29 @@ const processMessage = async (
 						}
 					}
 
+					// Persist tctokens carried by history-sync chats in BACKGROUND, serialised.
+					//
+					// Originally awaited (PR #386) to avoid 463 on first multi-device send, but in
+					// production this drained the event buffer per-chunk and added visible delivery
+					// latency (especially after restart / QR scan when many chunks arrived at once).
+					//
+					// `scheduleHistoryTcTokenSync` enqueues onto a single-concurrency promise chain
+					// (see definition above) — chunks persist sequentially in the order they were
+					// emitted, preserving timestamp monotonicity AND keeping the `__index` write
+					// safe from concurrent merge clobbers. The call returns immediately so the
+					// `messaging-history.set` emit is not blocked.
+					//
+					// TRADE-OFF: a listener that fires an outbound send IMMEDIATELY after the emit
+					// may race the still-pending persistence and get a 463 on that specific send.
+					// The existing 463 handler in messages-recv.ts triggers a getPrivacyTokens()
+					// refetch that auto-recovers within seconds. Net result is much better UX than
+					// per-chunk stalls.
+					//
+					// DO NOT add `await` back here without re-evaluating production latency, AND
+					// DO NOT call storeTcTokensFromHistorySync directly — it must go through the
+					// chain to preserve write ordering across overlapping chunks.
+					scheduleHistoryTcTokenSync(data.chats, signalRepository, keyStore, logger)
+
 					ev.emit('messaging-history.set', {
 						...data,
 						isLatest: histNotification.syncType !== proto.HistorySync.HistorySyncType.ON_DEMAND ? isLatest : undefined,

src/Utils/tc-token-utils.ts

@@ -1,12 +1,86 @@
 import type { SignalKeyStoreWithTransaction } from '../Types'
 import type { BinaryNode } from '../WABinary'
-import { getBinaryNodeChild, getBinaryNodeChildren, isLidUser, jidNormalizedUser } from '../WABinary'
+import {
+	getBinaryNodeChild,
+	getBinaryNodeChildren,
+	isAnyLidUser,
+	isAnyPnUser,
+	isHostedLidUser,
+	isHostedPnUser,
+	isJidMetaAI,
+	isLidUser,
+	isPnUser,
+	jidNormalizedUser
+} from '../WABinary'
 
 /** 7 days in seconds — matches WA Web AB prop tctoken_duration */
 const TC_TOKEN_BUCKET_DURATION = 604800
 /** 4 buckets → ~28-day rolling window — matches WA Web AB prop tctoken_num_buckets */
 const TC_TOKEN_NUM_BUCKETS = 4
 
+/**
+ * Sentinel key under the `tctoken` store holding a JSON array of tracked storage JIDs
+ * for cross-session pruning. Mirrors WA Web's CLEAN_TC_TOKENS index lookup.
+ *
+ * Exported so other modules (messages-recv, messages-send, process-message) reference
+ * the same constant. The fork previously inlined this string in messages-recv.ts;
+ * keep the value identical (`'__index'`) for backward compatibility with persisted state.
+ */
+export const TC_TOKEN_INDEX_KEY = '__index'
+
+// Phone-number pattern matching WABinary's isJidBot, applied against the user part so
+// the check is invariant to @c.us ↔ @s.whatsapp.net normalization.
+const BOT_PHONE_REGEX = /^1313555\d{4}$|^131655500\d{2}$/
+
+/**
+ * Mirrors WA Web's `Wid.isRegularUser()` (user ∧ ¬PSA ∧ ¬Bot). Used to gate tctoken
+ * storage against malformed notifications — WA Web filters server-side but we
+ * defend here for parity with `WAWebSetTcTokenChatAction.handleIncomingTcToken`.
+ * Works for both pre- and post-normalized JIDs (`@c.us` vs `@s.whatsapp.net`).
+ */
+export function isRegularUser(jid: string | undefined): boolean {
+	if (!jid) return false
+	const user = jid.split('@')[0] ?? ''
+	if (user === '0') return false // PSA
+	if (BOT_PHONE_REGEX.test(user)) return false // Bot by phone pattern
+	if (isJidMetaAI(jid)) return false // MetaAI (@bot server)
+	return !!(isPnUser(jid) || isLidUser(jid) || isHostedPnUser(jid) || isHostedLidUser(jid) || jid.endsWith('@c.us'))
+}
+
+/** Read the persisted tctoken JID index and return its entries (never contains the sentinel key itself). */
+export async function readTcTokenIndex(keys: SignalKeyStoreWithTransaction): Promise<string[]> {
+	const data = await keys.get('tctoken', [TC_TOKEN_INDEX_KEY])
+	const entry = data[TC_TOKEN_INDEX_KEY]
+	if (!entry?.token?.length) return []
+	try {
+		const parsed = JSON.parse(Buffer.from(entry.token).toString())
+		if (!Array.isArray(parsed)) return []
+		return parsed.filter((j): j is string => typeof j === 'string' && j.length > 0 && j !== TC_TOKEN_INDEX_KEY)
+	} catch {
+		return []
+	}
+}
+
+/**
+ * Build a SignalDataSet fragment that writes the merged index (persisted ∪ added)
+ * under the sentinel key. Lets callers update the index without clobbering writes
+ * made by other layers (history sync, concurrent sessions on the same store).
+ */
+export async function buildMergedTcTokenIndexWrite(
+	keys: SignalKeyStoreWithTransaction,
+	addedJids: Iterable<string>
+): Promise<{ [TC_TOKEN_INDEX_KEY]: { token: Buffer } }> {
+	const persisted = await readTcTokenIndex(keys)
+	const merged = new Set(persisted)
+	for (const jid of addedJids) {
+		if (jid && jid !== TC_TOKEN_INDEX_KEY) merged.add(jid)
+	}
+
+	return {
+		[TC_TOKEN_INDEX_KEY]: { token: Buffer.from(JSON.stringify([...merged])) }
+	}
+}
+
 /**
  * Check if a received token is expired using WA Web's rolling bucket algorithm.
  * Reference: WAWebTrustedContactsUtils.isTokenExpired
@@ -63,6 +137,43 @@ export async function resolveTcTokenJid(
 	return lid ?? normalized
 }
 
+/**
+ * Resolve target JID for issuing privacy token based on AB prop 14303
+ * (`lid_trusted_token_issue_to_lid`). When the prop is on, issuance goes to
+ * the LID; when off, it goes to the PN. Returns the original JID if no
+ * mapping is found in either direction.
+ *
+ * Normalizes the JID upfront and uses the `isAny*` helpers so callers can pass
+ * `@c.us`, `@s.whatsapp.net`, `@hosted`, `@hosted.lid`, `@lid` or device-specific
+ * forms — `LIDMappingStore.getLIDForPN` early-returns unless `isAnyPnUser`,
+ * so unnormalized inputs would silently bypass routing.
+ *
+ * Reference: WAWebTrustedContactsManager.issuePrivacyTokens
+ */
+export async function resolveIssuanceJid(
+	jid: string,
+	issueToLid: boolean,
+	getLIDForPN: (pn: string) => Promise<string | null>,
+	getPNForLID?: (lid: string) => Promise<string | null>
+): Promise<string> {
+	const normalized = jidNormalizedUser(jid)
+
+	if (issueToLid) {
+		if (isAnyLidUser(normalized)) return normalized
+		if (!isAnyPnUser(normalized)) return normalized
+		const lid = await getLIDForPN(normalized)
+		return lid ?? normalized
+	}
+
+	if (!isAnyLidUser(normalized)) return normalized
+	if (getPNForLID) {
+		const pn = await getPNForLID(normalized)
+		return pn ?? normalized
+	}
+
+	return normalized
+}
+
 type TcTokenParams = {
 	jid: string
 	baseContent?: BinaryNode[]
@@ -135,7 +246,13 @@ export async function storeTcTokensFromIqResult({
 			continue
 		}
 
-		const rawJid = jidNormalizedUser(tokenNode.attrs.jid || fallbackJid)
+		// In notifications, tokenNode.attrs.jid is OUR own device JID, not the sender's.
+		// Prefer fallbackJid (resolved from notification's `from` / `sender_lid`) so the
+		// token is stored under the peer's JID, never under self.
+		const rawJid = jidNormalizedUser(fallbackJid || tokenNode.attrs.jid)
+		// Defense against malformed notifications (PSA WID '0', bots, MetaAI). WA Web
+		// filters these server-side; we mirror Wid.isRegularUser() locally.
+		if (!isRegularUser(rawJid)) continue
 		const storageJid = await resolveTcTokenJid(rawJid, getLIDForPN)
 		const existingTcData = await keys.get('tctoken', [storageJid])
 		const existingEntry = existingTcData[storageJid]

src/__tests__/Socket/identity-change-handling.test.ts

@@ -297,4 +297,52 @@ describe('Identity Change Handling', () => {
 			expect(result.device).toBe(5)
 		})
 	})
+
+	describe('onBeforeSessionRefresh callback', () => {
+		it('fires before assertSessions when a session refresh is about to run', async () => {
+			mockValidateSession.mockResolvedValue({ exists: true })
+			const callOrder: string[] = []
+			mockAssertSessions.mockImplementation(async () => {
+				callOrder.push('assertSessions')
+				return true
+			})
+			const onBeforeSessionRefresh = jest.fn((jid: string) => {
+				callOrder.push(`before:${jid}`)
+			})
+
+			const node = createIdentityChangeNode('user@s.whatsapp.net')
+			const ctx = { ...createContext(), onBeforeSessionRefresh }
+			const result = await handleIdentityChange(node, ctx)
+
+			expect(result.action).toBe('session_refreshed')
+			expect(callOrder).toEqual(['before:user@s.whatsapp.net', 'assertSessions'])
+		})
+
+		it('does not fire when the refresh is skipped (no_identity / offline / self)', async () => {
+			const onBeforeSessionRefresh = jest.fn()
+
+			// no identity node
+			const noIdentityNode: BinaryNode = {
+				tag: 'notification',
+				attrs: { from: 'a@s.whatsapp.net', type: 'encrypt' },
+				content: []
+			}
+			await handleIdentityChange(noIdentityNode, { ...createContext(), onBeforeSessionRefresh })
+
+			// offline notification
+			mockValidateSession.mockResolvedValue({ exists: true })
+			await handleIdentityChange(createIdentityChangeNode('b@s.whatsapp.net', '0'), {
+				...createContext(),
+				onBeforeSessionRefresh
+			})
+
+			// self primary
+			await handleIdentityChange(createIdentityChangeNode(mockMeId!), {
+				...createContext(),
+				onBeforeSessionRefresh
+			})
+
+			expect(onBeforeSessionRefresh).not.toHaveBeenCalled()
+		})
+	})
 })

src/__tests__/Utils/tc-token.test.ts

@@ -1,7 +1,17 @@
 import { jest } from '@jest/globals'
 import { DisconnectReason, type SignalKeyStoreWithTransaction } from '../../Types'
 import { getErrorCodeFromStreamError, SERVER_ERROR_CODES } from '../../Utils'
-import { buildTcTokenFromJid, isTcTokenExpired, shouldSendNewTcToken } from '../../Utils/tc-token-utils'
+import {
+	buildMergedTcTokenIndexWrite,
+	buildTcTokenFromJid,
+	isRegularUser,
+	isTcTokenExpired,
+	readTcTokenIndex,
+	resolveIssuanceJid,
+	shouldSendNewTcToken,
+	storeTcTokensFromIqResult,
+	TC_TOKEN_INDEX_KEY
+} from '../../Utils/tc-token-utils'
 import type { BinaryNode } from '../../WABinary'
 
 /** 7 days in seconds — matches WA Web tctoken_duration */
@@ -848,3 +858,340 @@ describe('tctoken integration scenarios', () => {
 		})
 	})
 })
+
+// ─── isRegularUser (PSA / bot / MetaAI gating) ─────────────────────────
+
+describe('isRegularUser', () => {
+	it('rejects undefined / empty', () => {
+		expect(isRegularUser(undefined)).toBe(false)
+		expect(isRegularUser('')).toBe(false)
+	})
+
+	it('rejects PSA WID (user "0")', () => {
+		expect(isRegularUser('0@s.whatsapp.net')).toBe(false)
+		expect(isRegularUser('0@c.us')).toBe(false)
+	})
+
+	it('rejects bot phone numbers (1313555XXXX, 131655500XX)', () => {
+		expect(isRegularUser('13135550000@s.whatsapp.net')).toBe(false)
+		expect(isRegularUser('13135559999@s.whatsapp.net')).toBe(false)
+		// /^131655500\d{2}$/ — 11 digits: 131655500 + 2 trailing
+		expect(isRegularUser('13165550000@s.whatsapp.net')).toBe(false)
+		expect(isRegularUser('13165550099@s.whatsapp.net')).toBe(false)
+	})
+
+	it('rejects MetaAI (@bot server)', () => {
+		expect(isRegularUser('foo@bot')).toBe(false)
+	})
+
+	it('accepts regular PN users (@s.whatsapp.net, @c.us)', () => {
+		expect(isRegularUser('5511999999999@s.whatsapp.net')).toBe(true)
+		expect(isRegularUser('5511999999999@c.us')).toBe(true)
+	})
+
+	it('accepts LID users', () => {
+		expect(isRegularUser('123456@lid')).toBe(true)
+	})
+
+	it('accepts hosted PN/LID users', () => {
+		expect(isRegularUser('5511999999999@hosted')).toBe(true)
+		expect(isRegularUser('123456@hosted.lid')).toBe(true)
+	})
+})
+
+// ─── resolveIssuanceJid (AB prop 14303 routing) ────────────────────────
+
+describe('resolveIssuanceJid', () => {
+	const PN = '5511999999999@s.whatsapp.net'
+	const LID = '123456@lid'
+	const PN_NO_LID = '5511888888888@s.whatsapp.net'
+	const LID_NO_PN = '999999@lid'
+
+	const getLIDForPN = jest.fn<(pn: string) => Promise<string | null>>(async (pn: string) => {
+		if (pn === PN) return LID
+		return null
+	})
+	const getPNForLID = jest.fn<(lid: string) => Promise<string | null>>(async (lid: string) => {
+		if (lid === LID) return PN
+		return null
+	})
+
+	beforeEach(() => {
+		getLIDForPN.mockClear()
+		getPNForLID.mockClear()
+	})
+
+	describe('AB prop 14303 ON (issueToLid=true)', () => {
+		it('returns LID unchanged when input is LID', async () => {
+			expect(await resolveIssuanceJid(LID, true, getLIDForPN, getPNForLID)).toBe(LID)
+			expect(getLIDForPN).not.toHaveBeenCalled()
+		})
+
+		it('resolves PN to LID via lidMapping', async () => {
+			expect(await resolveIssuanceJid(PN, true, getLIDForPN, getPNForLID)).toBe(LID)
+			expect(getLIDForPN).toHaveBeenCalledWith(PN)
+		})
+
+		it('falls back to original PN when no LID mapping exists', async () => {
+			expect(await resolveIssuanceJid(PN_NO_LID, true, getLIDForPN, getPNForLID)).toBe(PN_NO_LID)
+		})
+	})
+
+	describe('AB prop 14303 OFF (issueToLid=false)', () => {
+		it('returns PN unchanged when input is PN', async () => {
+			expect(await resolveIssuanceJid(PN, false, getLIDForPN, getPNForLID)).toBe(PN)
+			expect(getPNForLID).not.toHaveBeenCalled()
+		})
+
+		it('resolves LID to PN via lidMapping', async () => {
+			expect(await resolveIssuanceJid(LID, false, getLIDForPN, getPNForLID)).toBe(PN)
+			expect(getPNForLID).toHaveBeenCalledWith(LID)
+		})
+
+		it('falls back to original LID when no PN mapping exists', async () => {
+			expect(await resolveIssuanceJid(LID_NO_PN, false, getLIDForPN, getPNForLID)).toBe(LID_NO_PN)
+		})
+
+		it('returns LID unchanged when getPNForLID is omitted', async () => {
+			expect(await resolveIssuanceJid(LID, false, getLIDForPN)).toBe(LID)
+		})
+	})
+
+	describe('JID normalization (handles @c.us and hosted forms)', () => {
+		const PN_CUS = '5511999999999@c.us'
+		const PN_NORMALIZED = '5511999999999@s.whatsapp.net'
+		const HOSTED_LID = '999999@hosted.lid'
+
+		it('normalizes @c.us before resolving (issueToLid=true)', async () => {
+			const fn = jest.fn<(pn: string) => Promise<string | null>>(async (pn: string) => {
+				if (pn === PN_NORMALIZED) return LID
+				return null
+			})
+			const result = await resolveIssuanceJid(PN_CUS, true, fn, getPNForLID)
+			expect(result).toBe(LID)
+			// Mapping store called with NORMALIZED form
+			expect(fn).toHaveBeenCalledWith(PN_NORMALIZED)
+		})
+
+		it('treats hosted LID as LID input (issueToLid=true returns it unchanged)', async () => {
+			expect(await resolveIssuanceJid(HOSTED_LID, true, getLIDForPN, getPNForLID)).toBe(HOSTED_LID)
+			expect(getLIDForPN).not.toHaveBeenCalled()
+		})
+
+		it('treats hosted LID as LID input (issueToLid=false converts via getPNForLID)', async () => {
+			const fn = jest.fn<(lid: string) => Promise<string | null>>(async () => null)
+			await resolveIssuanceJid(HOSTED_LID, false, getLIDForPN, fn)
+			expect(fn).toHaveBeenCalledWith(HOSTED_LID)
+		})
+	})
+})
+
+// ─── readTcTokenIndex / buildMergedTcTokenIndexWrite ───────────────────
+
+describe('tctoken cross-session prune index', () => {
+	it('exports the sentinel key as "__index"', () => {
+		// Persisted state compatibility — tests freeze the value to catch unintended renames.
+		expect(TC_TOKEN_INDEX_KEY).toBe('__index')
+	})
+
+	describe('readTcTokenIndex', () => {
+		it('returns [] when the index entry is absent', async () => {
+			const keys = createMockKeys()
+			;(keys.get as any).mockResolvedValue({})
+			expect(await readTcTokenIndex(keys)).toEqual([])
+		})
+
+		it('returns [] when the index token buffer is empty', async () => {
+			const keys = createMockKeys()
+			;(keys.get as any).mockResolvedValue({ [TC_TOKEN_INDEX_KEY]: { token: Buffer.alloc(0) } })
+			expect(await readTcTokenIndex(keys)).toEqual([])
+		})
+
+		it('returns [] when the JSON payload is corrupted', async () => {
+			const keys = createMockKeys()
+			;(keys.get as any).mockResolvedValue({ [TC_TOKEN_INDEX_KEY]: { token: Buffer.from('not-json') } })
+			expect(await readTcTokenIndex(keys)).toEqual([])
+		})
+
+		it('returns [] when the JSON payload is not an array', async () => {
+			const keys = createMockKeys()
+			;(keys.get as any).mockResolvedValue({ [TC_TOKEN_INDEX_KEY]: { token: Buffer.from('{"a":1}') } })
+			expect(await readTcTokenIndex(keys)).toEqual([])
+		})
+
+		it('returns the persisted JIDs', async () => {
+			const keys = createMockKeys()
+			const stored = ['a@lid', 'b@lid', 'c@s.whatsapp.net']
+			;(keys.get as any).mockResolvedValue({
+				[TC_TOKEN_INDEX_KEY]: { token: Buffer.from(JSON.stringify(stored)) }
+			})
+			expect(await readTcTokenIndex(keys)).toEqual(stored)
+		})
+
+		it('filters out the sentinel key itself, empty strings, and non-strings', async () => {
+			const keys = createMockKeys()
+			const stored = ['a@lid', '', TC_TOKEN_INDEX_KEY, 42, null, 'b@lid']
+			;(keys.get as any).mockResolvedValue({
+				[TC_TOKEN_INDEX_KEY]: { token: Buffer.from(JSON.stringify(stored)) }
+			})
+			expect(await readTcTokenIndex(keys)).toEqual(['a@lid', 'b@lid'])
+		})
+	})
+
+	describe('buildMergedTcTokenIndexWrite', () => {
+		it('merges added JIDs with the persisted set (de-duplicated)', async () => {
+			const keys = createMockKeys()
+			;(keys.get as any).mockResolvedValue({
+				[TC_TOKEN_INDEX_KEY]: { token: Buffer.from(JSON.stringify(['a@lid', 'b@lid'])) }
+			})
+			const write = await buildMergedTcTokenIndexWrite(keys, ['b@lid', 'c@lid'])
+			const decoded = JSON.parse(write[TC_TOKEN_INDEX_KEY].token.toString()) as string[]
+			expect(decoded.sort()).toEqual(['a@lid', 'b@lid', 'c@lid'])
+		})
+
+		it('drops the sentinel key from the added set', async () => {
+			const keys = createMockKeys()
+			;(keys.get as any).mockResolvedValue({})
+			const write = await buildMergedTcTokenIndexWrite(keys, [TC_TOKEN_INDEX_KEY, 'a@lid'])
+			const decoded = JSON.parse(write[TC_TOKEN_INDEX_KEY].token.toString()) as string[]
+			expect(decoded).toEqual(['a@lid'])
+		})
+
+		it('handles empty inputs', async () => {
+			const keys = createMockKeys()
+			;(keys.get as any).mockResolvedValue({})
+			const write = await buildMergedTcTokenIndexWrite(keys, [])
+			const decoded = JSON.parse(write[TC_TOKEN_INDEX_KEY].token.toString()) as string[]
+			expect(decoded).toEqual([])
+		})
+	})
+})
+
+// ─── storeTcTokensFromIqResult — isRegularUser gating + monotonicity ───
+
+describe('storeTcTokensFromIqResult — gating and monotonicity', () => {
+	const PEER_PN = '5511999999999@s.whatsapp.net'
+	const PEER_LID = '123456@lid'
+
+	const getLIDForPN = jest.fn<(pn: string) => Promise<string | null>>(async (pn: string) => {
+		if (pn === PEER_PN) return PEER_LID
+		return null
+	})
+
+	beforeEach(() => {
+		getLIDForPN.mockClear()
+	})
+
+	const buildIqResult = (jid: string, tokenBytes: Uint8Array, t: string): BinaryNode => ({
+		tag: 'iq',
+		attrs: {},
+		content: [
+			{
+				tag: 'tokens',
+				attrs: {},
+				content: [
+					{
+						tag: 'token',
+						attrs: { jid, type: 'trusted_contact', t },
+						content: tokenBytes
+					}
+				]
+			}
+		]
+	})
+
+	it('skips PSA WID (jid="0") even if returned in tokens block', async () => {
+		const keys = createMockKeys()
+		;(keys.get as any).mockResolvedValue({})
+		await storeTcTokensFromIqResult({
+			result: buildIqResult('myDeviceJid@s.whatsapp.net', Buffer.from([0x01, 0x02]), '1700000000'),
+			fallbackJid: '0@s.whatsapp.net',
+			keys,
+			getLIDForPN
+		})
+		expect(keys.set).not.toHaveBeenCalled()
+	})
+
+	it('skips bot phone numbers', async () => {
+		const keys = createMockKeys()
+		;(keys.get as any).mockResolvedValue({})
+		await storeTcTokensFromIqResult({
+			result: buildIqResult('myDeviceJid@s.whatsapp.net', Buffer.from([0x01, 0x02]), '1700000000'),
+			fallbackJid: '13135550000@s.whatsapp.net',
+			keys,
+			getLIDForPN
+		})
+		expect(keys.set).not.toHaveBeenCalled()
+	})
+
+	it('skips MetaAI (@bot server)', async () => {
+		const keys = createMockKeys()
+		;(keys.get as any).mockResolvedValue({})
+		await storeTcTokensFromIqResult({
+			result: buildIqResult('myDeviceJid@s.whatsapp.net', Buffer.from([0x01, 0x02]), '1700000000'),
+			fallbackJid: 'meta-ai@bot',
+			keys,
+			getLIDForPN
+		})
+		expect(keys.set).not.toHaveBeenCalled()
+	})
+
+	it('uses fallbackJid (NOT the token node jid which is own device) as storage source', async () => {
+		const keys = createMockKeys()
+		;(keys.get as any).mockResolvedValue({})
+		const onNewJidStored = jest.fn()
+		await storeTcTokensFromIqResult({
+			result: buildIqResult('myDeviceJid:1@s.whatsapp.net', Buffer.from([0xaa, 0xbb]), '1700000000'),
+			fallbackJid: PEER_PN,
+			keys,
+			getLIDForPN,
+			onNewJidStored
+		})
+		expect(keys.set).toHaveBeenCalled()
+		const setArgs = (keys.set.mock.calls[0]?.[0] as { tctoken: Record<string, unknown> }).tctoken
+		expect(Object.keys(setArgs)).toContain(PEER_LID)
+		expect(onNewJidStored).toHaveBeenCalledWith(PEER_LID)
+	})
+
+	it('skips when incoming timestamp is older than existing (monotonicity)', async () => {
+		const keys = createMockKeys()
+		;(keys.get as any).mockResolvedValue({
+			[PEER_LID]: { token: Buffer.from([0x99]), timestamp: '1800000000' }
+		})
+		await storeTcTokensFromIqResult({
+			result: buildIqResult('myDeviceJid@s.whatsapp.net', Buffer.from([0xaa]), '1700000000'),
+			fallbackJid: PEER_PN,
+			keys,
+			getLIDForPN
+		})
+		expect(keys.set).not.toHaveBeenCalled()
+	})
+
+	it('skips timestamp-less tokens (would be immediately expired)', async () => {
+		const keys = createMockKeys()
+		;(keys.get as any).mockResolvedValue({})
+		await storeTcTokensFromIqResult({
+			result: {
+				tag: 'iq',
+				attrs: {},
+				content: [
+					{
+						tag: 'tokens',
+						attrs: {},
+						content: [
+							{
+								tag: 'token',
+								attrs: { jid: 'd@s.whatsapp.net', type: 'trusted_contact' },
+								content: Buffer.from([0x01])
+							}
+						]
+					}
+				]
+			},
+			fallbackJid: PEER_PN,
+			keys,
+			getLIDForPN
+		})
+		expect(keys.set).not.toHaveBeenCalled()
+	})
+})

src/__tests__/bigint-validation.test.ts

@@ -0,0 +1,209 @@
+import Long from 'long'
+import $protobuf from 'protobufjs/minimal.js'
+
+const $util = $protobuf.util
+
+// proto implementation
+function longToStringOld(value: any, unsigned?: boolean): string {
+	if (typeof value === 'string') return value
+	if (typeof value === 'number') return String(value)
+	if (!$util.Long) return String(value)
+	const normalized = ($util.Long as any).fromValue(value)
+	const prepared =
+		unsigned && normalized && typeof normalized.toUnsigned === 'function' ? normalized.toUnsigned() : normalized
+	return prepared.toString()
+}
+
+// bigint implementation
+function longToStringNew(value: any, unsigned?: boolean): string {
+	if (typeof value === 'string') return value
+	if (typeof value === 'number') return String(value)
+	if (value && typeof value.low === 'number' && typeof value.high === 'number') {
+		const high = value.high | 0
+		const lo = BigInt(value.low >>> 0)
+		const hi = BigInt(value.high >>> 0)
+		const combined = (hi << 32n) | lo
+		if (!unsigned && high < 0) {
+			return (combined - (1n << 64n)).toString()
+		}
+
+		return combined.toString()
+	}
+
+	return String(value)
+}
+
+function longToNumberOld(value: any, unsigned?: boolean): number {
+	if (typeof value === 'number') return value
+	if (typeof value === 'string') return Number(value)
+	if (!$util.Long) return Number(value)
+	const normalized = ($util.Long as any).fromValue(value)
+	const prepared =
+		unsigned && normalized && typeof normalized.toUnsigned === 'function'
+			? normalized.toUnsigned()
+			: typeof normalized.toSigned === 'function'
+				? normalized.toSigned()
+				: normalized
+	return prepared.toNumber()
+}
+
+function longToNumberNew(value: any, unsigned?: boolean): number {
+	if (typeof value === 'number') return value
+	if (typeof value === 'string') return Number(value)
+	if (value && typeof value.low === 'number' && typeof value.high === 'number') {
+		const high = value.high | 0
+		const lo = BigInt(value.low >>> 0)
+		const hi = BigInt(value.high >>> 0)
+		const combined = (hi << 32n) | lo
+		if (!unsigned && high < 0) {
+			return Number(combined - (1n << 64n))
+		}
+
+		return Number(combined)
+	}
+
+	return Number(value)
+}
+
+describe('BigInt vs Long equivalence validation', () => {
+	// Test cases: [description, Long value, unsigned flag]
+	const testCases: [string, Long, boolean][] = [
+		// Basic values
+		['zero unsigned', Long.fromNumber(0, true), true],
+		['zero signed', Long.fromNumber(0, false), false],
+		['one unsigned', Long.fromNumber(1, true), true],
+		['one signed', Long.fromNumber(1, false), false],
+
+		// Typical WhatsApp timestamps (seconds since epoch)
+		['timestamp 2023', Long.fromNumber(1700000000, true), true],
+		['timestamp 2025', Long.fromNumber(1750000000, true), true],
+		['timestamp as signed', Long.fromNumber(1700000000, false), false],
+
+		// File sizes
+		['small file', Long.fromNumber(1024, true), true],
+		['medium file 10MB', Long.fromNumber(10485760, true), true],
+		['large file 2GB', Long.fromNumber(2147483648, true), true],
+
+		// Boundary values - 32-bit
+		['max int32', Long.fromNumber(2147483647, false), false],
+		['min int32', Long.fromNumber(-2147483648, false), false],
+		['max uint32', Long.fromNumber(4294967295, true), true],
+
+		// Around MAX_SAFE_INTEGER
+		['MAX_SAFE_INTEGER', Long.fromString('9007199254740991', false), false],
+		['MAX_SAFE_INTEGER + 1', Long.fromString('9007199254740992', false), false],
+		['MAX_SAFE_INTEGER unsigned', Long.fromString('9007199254740991', true), true],
+
+		// Large unsigned values
+		['large unsigned', Long.fromString('9999999999999999999', true), true],
+		['max uint64', Long.fromString('18446744073709551615', true), true],
+		['max uint64 - 1', Long.fromString('18446744073709551614', true), true],
+
+		// Signed negative values
+		['negative one', Long.fromNumber(-1, false), false],
+		['negative small', Long.fromNumber(-100, false), false],
+		['negative large', Long.fromNumber(-2147483648, false), false],
+		['min int64', Long.fromString('-9223372036854775808', false), false],
+		['max int64', Long.fromString('9223372036854775807', false), false],
+		['-1 as signed Long', Long.fromBits(-1, -1, false), false],
+
+		// Tricky bit patterns
+		['high=1, low=0', Long.fromBits(0, 1, true), true],
+		['high=0, low=-1 (0xFFFFFFFF)', Long.fromBits(-1, 0, true), true],
+		['high=-1, low=-1 unsigned (max uint64)', Long.fromBits(-1, -1, true), true],
+		['high=0x7FFFFFFF, low=0xFFFFFFFF (max int64)', Long.fromBits(-1, 0x7fffffff, false), false],
+		['high=0x80000000, low=0 (min int64)', Long.fromBits(0, -2147483648, false), false],
+
+		// Powers of 2
+		['2^32', Long.fromString('4294967296', true), true],
+		['2^32 signed', Long.fromString('4294967296', false), false],
+		['2^48', Long.fromString('281474976710656', true), true],
+		['2^63', Long.fromString('9223372036854775808', true), true]
+	]
+
+	describe('longToString equivalence', () => {
+		for (const [desc, longVal, unsigned] of testCases) {
+			it(`${desc}: Long(${longVal.low}, ${longVal.high}, ${unsigned})`, () => {
+				const oldResult = longToStringOld(longVal, unsigned)
+				const newResult = longToStringNew(longVal, unsigned)
+				expect(newResult).toBe(oldResult)
+			})
+		}
+	})
+
+	describe('longToNumber equivalence', () => {
+		for (const [desc, longVal, unsigned] of testCases) {
+			it(`${desc}: Long(${longVal.low}, ${longVal.high}, ${unsigned})`, () => {
+				const oldResult = longToNumberOld(longVal, unsigned)
+				const newResult = longToNumberNew(longVal, unsigned)
+				// For large values, both may lose precision equally (Number limitation)
+				// So we compare string representations
+				expect(newResult.toString()).toBe(oldResult.toString())
+			})
+		}
+	})
+
+	describe('non-Long inputs (fallback paths)', () => {
+		it('string passthrough', () => {
+			expect(longToStringNew('12345')).toBe('12345')
+			expect(longToStringNew('0')).toBe('0')
+		})
+		it('number passthrough', () => {
+			expect(longToStringNew(42)).toBe('42')
+			expect(longToStringNew(0)).toBe('0')
+			expect(longToStringNew(-1)).toBe('-1')
+		})
+		it('null/undefined fallback', () => {
+			expect(longToStringNew(null)).toBe('null')
+			expect(longToStringNew(undefined)).toBe('undefined')
+		})
+		it('object without low/high', () => {
+			expect(longToStringNew({ foo: 'bar' })).toBe('[object Object]')
+		})
+
+		// Defensive: a raw {low, high} JSON object can carry `high` as an
+		// unsigned 32-bit value (Long.fromBits would normalize via `| 0`,
+		// but plain JSON deserialization does not). Without `value.high | 0`
+		// the sign-bit check fails and the result is interpreted as unsigned.
+		// Upstream Baileys PR #2333 has this latent bug; InfiniteAPI fixes it.
+		it('signed sign-bit detection on raw unsigned high (-1 as {low: -1, high: 4294967295})', () => {
+			const raw = { low: -1, high: 0xffffffff }
+			// signed: -1
+			expect(longToStringNew(raw, false)).toBe('-1')
+			// unsigned: max uint64
+			expect(longToStringNew(raw, true)).toBe('18446744073709551615')
+		})
+
+		it('signed sign-bit detection on raw unsigned high (-4294967296 as {low: 0, high: 4294967295})', () => {
+			const raw = { low: 0, high: 0xffffffff }
+			// signed: -4294967296 (high word = -1 after normalization)
+			expect(longToStringNew(raw, false)).toBe('-4294967296')
+			// unsigned: 0xFFFFFFFF00000000 = 18446744069414584320
+			expect(longToStringNew(raw, true)).toBe('18446744069414584320')
+		})
+	})
+
+	describe('fuzz: random Long values', () => {
+		it('100 random unsigned values match', () => {
+			for (let i = 0; i < 100; i++) {
+				const low = (Math.random() * 0xffffffff) | 0
+				const high = (Math.random() * 0xffffffff) | 0
+				const longVal = Long.fromBits(low, high, true)
+				const oldResult = longToStringOld(longVal, true)
+				const newResult = longToStringNew(longVal, true)
+				expect(newResult).toBe(oldResult)
+			}
+		})
+
+		it('100 random signed values match', () => {
+			for (let i = 0; i < 100; i++) {
+				const low = (Math.random() * 0xffffffff) | 0
+				const high = (Math.random() * 0xffffffff) | 0
+				const longVal = Long.fromBits(low, high, false)
+				const oldResult = longToStringOld(longVal, false)
+				const newResult = longToStringNew(longVal, false)
+				expect(newResult).toBe(oldResult)
+			}
+		})
+	})
+})

src/__tests__/proto-tojson-long.test.ts

@@ -1,3 +1,4 @@
+import Long from 'long'
 import '../index.js'
 import { proto } from '../../WAProto/index.js'
 
@@ -28,4 +29,91 @@ describe('proto serialization', () => {
 		const json = message.toJSON()
 		expect(json.message?.imageMessage?.fileLength).toBe('1234567890123456789')
 	})
+
+	it('converts Long objects to strings correctly via BigInt fast path', () => {
+		const message = proto.WebMessageInfo.fromObject({
+			key: {
+				remoteJid: '123@s.whatsapp.net',
+				id: 'ABC123',
+				fromMe: false
+			},
+			messageTimestamp: Long.fromNumber(1700000000, true),
+			message: {
+				imageMessage: {
+					fileLength: Long.fromString('9876543210', true)
+				}
+			}
+		})
+
+		const json = message.toJSON()
+		expect(json.messageTimestamp).toBe('1700000000')
+		expect(json.message?.imageMessage?.fileLength).toBe('9876543210')
+	})
+
+	it('handles large unsigned Long values (> MAX_SAFE_INTEGER)', () => {
+		const message = proto.WebMessageInfo.fromObject({
+			key: {
+				remoteJid: '123@s.whatsapp.net',
+				id: 'ABC123',
+				fromMe: false
+			},
+			messageTimestamp: Long.fromString('18446744073709551615', true), // max uint64
+			message: {
+				imageMessage: {
+					fileLength: Long.fromString('9999999999999999999', true)
+				}
+			}
+		})
+
+		const json = message.toJSON()
+		expect(json.messageTimestamp).toBe('18446744073709551615')
+		expect(json.message?.imageMessage?.fileLength).toBe('9999999999999999999')
+	})
+
+	it('handles zero and small Long values', () => {
+		const message = proto.WebMessageInfo.fromObject({
+			key: {
+				remoteJid: '123@s.whatsapp.net',
+				id: 'ABC123',
+				fromMe: false
+			},
+			messageTimestamp: Long.fromNumber(0, true),
+			message: {
+				imageMessage: {
+					fileLength: Long.fromNumber(1, true)
+				}
+			}
+		})
+
+		const json = message.toJSON()
+		expect(json.messageTimestamp).toBe('0')
+		expect(json.message?.imageMessage?.fileLength).toBe('1')
+	})
+
+	it('roundtrips encode/decode with Long fields preserving values (> MAX_SAFE_INTEGER)', () => {
+		// Use uint64 values above Number.MAX_SAFE_INTEGER (2^53 - 1) so the
+		// roundtrip actually exercises the BigInt fast path on decode->toJSON.
+		// Safe integers would silently work even if longToString fell back to
+		// Number(value).
+		const original = proto.WebMessageInfo.fromObject({
+			key: {
+				remoteJid: '123@s.whatsapp.net',
+				id: 'ABC123',
+				fromMe: false
+			},
+			messageTimestamp: Long.fromString('18446744073709551615', true),
+			message: {
+				imageMessage: {
+					fileLength: Long.fromString('9999999999999999999', true)
+				}
+			}
+		})
+
+		const encoded = proto.WebMessageInfo.encode(original).finish()
+		const decoded = proto.WebMessageInfo.decode(encoded)
+		const json = decoded.toJSON()
+
+		expect(json.messageTimestamp).toBe('18446744073709551615')
+		expect(json.message?.imageMessage?.fileLength).toBe('9999999999999999999')
+	})
 })