fix: preserve full Error for unknown decrypt failures + improve dedup comment

Addresses 3 distinct PR #391 review findings (Copilot Major + Codex P2 + Copilot
nitpick — all valid):

#2 Copilot Major + #4 Codex P2 (same root, MAJOR):
   The previous slim of `errorContext.err` to `{name, message, type}` was applied
   uniformly to all three decrypt-failure branches. The unknown-error branch
   (lines 481-491 — "Unknown/unexpected errors (protobuf, parsing, etc.)") is
   exactly where stack traces matter MOST: there's no recovery path for those,
   so production root-cause analysis depends on having the stack.

   FIX: condition `errorContext.err` on category. Only slim for known-recoverable
   categories (corrupted-session / session-record). Unknown errors keep the full
   originalError so logger.error pino still emits the stack. Adds the
   `isRecoverableCategory` flag to make the intent obvious to future readers.

#3 Copilot (related to #2):
   The previous comment claimed "Full stack is still available via originalError
   if needed in custom handlers" — but originalError wasn't actually exposed
   anywhere downstream and the error wasn't re-thrown. Updated the comment to
   reflect the new conditional behavior (slim only for recoverable cases) so
   future maintainers don't misread the intent.

#1 Copilot (dedup window comment, MINOR):
   The 5000ms dedup window in src/index.ts can suppress genuinely-different
   errors for the same JID within the window. Kept the 5s value (it's the right
   trade-off for noisy production streams) but expanded the comment to spell
   out the trade-off and how to bypass it (BAILEYS_LOG_LEVEL=debug).

Skipped: nothing — all reviewer points addressed.

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

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

src/Socket/messages-recv.ts

@@ -2330,44 +2330,54 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		)
 
 		const alt = msg.key.participantAlt || msg.key.remoteJidAlt
-		// Handle LID/PN mappings with hybrid approach:
+		// Handle LID/PN mappings with optimized hot-path:
-		// - Store mapping operation runs in background (non-critical for decrypt)
+		// - storeLIDPNMappings is fire-and-forget (background) — does NOT block decrypt
-		// - Session migration MUST complete before decrypt() to avoid "No session record" errors
+		// - migrateSession is SYNC (await) — REQUIRED for decrypt to find session
-		// This addresses Codex/Copilot review concerns about race conditions with decrypt()
+		//
+		// 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
+				// Fire-and-forget: storeLIDPNMappings has internal cache+dedup,
-				const existingMapping = await signalRepository.lidMapping.getPNForLID(alt)
+				// pre-check (getPNForLID) was redundant.
-				if (!existingMapping) {
+				signalRepository.lidMapping
-					// MUST await: normalizeMessageJids() runs after this and needs the mapping
+					.storeLIDPNMappings([{ lid: alt, pn: primaryJid }])
-					// in the LIDMappingStore to resolve LID→PN for events delivered to consumers
+					.catch(error => logger.warn({ error, alt, primaryJid }, 'background LID mapping store failed'))
-					await signalRepository.lidMapping
-						.storeLIDPNMappings([{ lid: alt, pn: primaryJid }])
-						.catch(error => logger.warn({ error, alt, primaryJid }, 'LID mapping storage failed'))
-				}
 
-				// CRITICAL: ALWAYS migrate session, even if mapping exists
+				// CRITICAL: ALWAYS migrate session SYNC, even if mapping exists.
-				// Other code paths (e.g., USync device lookup in messages-send.ts:310-319)
+				// Other code paths (e.g., USync device lookup in messages-send.ts) may create
-				// may create mappings via storeLIDPNMappings() without calling migrateSession()
+				// mappings via storeLIDPNMappings() without calling migrateSession(). This
-				// This leaves sessions under PN format while decrypt() expects LID format
+				// leaves sessions under PN format while decrypt() expects LID format.
-				// Skipping migration based on mapping existence causes "No session record" errors
+				// Skipping migration based on mapping existence causes "No session record" errors.
 				await signalRepository.migrateSession(primaryJid, alt)
 			} else {
-				// Check if reverse mapping exists
+				// Fire-and-forget: same rationale as above.
-				const existingMapping = await signalRepository.lidMapping.getLIDForPN(alt)
+				signalRepository.lidMapping
-				if (!existingMapping) {
+					.storeLIDPNMappings([{ lid: primaryJid, pn: alt }])
-					// MUST await: normalizeMessageJids() runs after this and needs the mapping
+					.catch(error => logger.warn({ error, alt, primaryJid }, 'background LID mapping store failed'))
-					// 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'))
-				}
 
-				// CRITICAL: ALWAYS migrate session, even if mapping exists
+				// CRITICAL: ALWAYS migrate session SYNC.
-				// Same reasoning as above - mapping existence doesn't guarantee session migration
 				await signalRepository.migrateSession(alt, primaryJid)
 			}
 		}

src/Utils/auth-utils.ts

@@ -341,7 +341,18 @@ export const addTransactionCapability = (
 
 						return result
 					} catch (error) {
-						logger.error({ error }, 'transaction failed, rolling back')
+						// SessionError is part of the normal Bad MAC recovery flow
+						// (retry receipt → sender resends as pkmsg → new session within ~1.3s).
+						// Logging it as ERROR creates 2 noise lines per recoverable Bad MAC cycle.
+						// Downgrade to debug for SessionError; keep ERROR for everything else.
+						// The error is still re-thrown — recovery behavior is unchanged.
+						const errName = (error as { name?: string })?.name
+						if (errName === 'SessionError') {
+							logger.debug({ error }, 'transaction failed (SessionError — recoverable via retry receipt)')
+						} else {
+							logger.error({ error }, 'transaction failed, rolling back')
+						}
+
 						throw error
 					}
 				})

src/Utils/decode-wa-message.ts

@@ -58,7 +58,11 @@ export const BAD_MAC_ERROR_TEXT = 'Bad MAC'
 export const DECRYPTION_RETRY_CONFIG = {
 	maxRetries: 3,
 	baseDelayMs: 100,
-	sessionRecordErrors: ['No session record', 'SessionError: No session record'],
+	// 'No matching sessions found' is the libsignal error when decryptWithSessions exhausts
+	// all stored sessions for a JID. Same recovery flow (retry receipt → pkmsg → new session)
+	// — categorise it as session-record so the caller logs DEBUG on retry, ERROR only when
+	// retries are exhausted (instead of dumping the full stack as an unknown error).
+	sessionRecordErrors: ['No session record', 'SessionError: No session record', 'No matching sessions found'],
 	corruptedSessionErrors: ['Bad MAC', 'MessageCounterError', MISSING_KEYS_ERROR_TEXT]
 }
 
@@ -421,9 +425,26 @@ export const decryptMessageNode = (
 						const isCorrupted = isCorruptedSessionError(originalError)
 						const isSessionRecord = isSessionRecordError(originalError)
 
+						// Slim error projection — keep name/message/type for diagnosis,
+						// drop `stack` which adds 4-5 lines of node_modules paths per log
+						// for known-recoverable libsignal errors.
+						//
+						// CRITICAL: only slim for KNOWN-RECOVERABLE categories (corrupted /
+						// session-record). The unknown-error branch keeps the full Error so
+						// protobuf/parsing/runtime bugs still emit a stack trace where it
+						// matters most. Catches Copilot/Codex P2 review on PR #391.
+						const slimErr = originalError
+							? {
+									name: (originalError as { name?: string }).name,
+									message: (originalError as { message?: string }).message,
+									type: (originalError as { type?: string }).type
+								}
+							: undefined
+						const isRecoverableCategory = isCorrupted || isSessionRecord
+
 						const errorContext = {
 							key: fullMessage.key,
-							err: originalError,
+							err: isRecoverableCategory ? slimErr : originalError,
 							messageType: tag === 'plaintext' ? 'plaintext' : attrs.type,
 							sender,
 							author,

src/Utils/process-message.ts

@@ -82,6 +82,47 @@ const REAL_MSG_REQ_ME_STUB_TYPES = new Set([WAMessageStubType.GROUP_PARTICIPANT_
  * (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,
@@ -565,11 +606,28 @@ const processMessage = async (
 						}
 					}
 
-					// Persist tctokens carried by history-sync chats BEFORE emitting messaging-history.set
+					// Persist tctokens carried by history-sync chats in BACKGROUND, serialised.
-					// — listeners may immediately fire outbound sends that need the tctoken, and the store
+					//
-					// has to be populated first to avoid an error 463 on the first multi-device send.
+					// Originally awaited (PR #386) to avoid 463 on first multi-device send, but in
-					// Runs AFTER storeLIDPNMappings (see comment above) so LID resolution works.
+					// production this drained the event buffer per-chunk and added visible delivery
-					await storeTcTokensFromHistorySync(data.chats, signalRepository, keyStore, logger)
+					// 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,

src/index.ts

@@ -28,7 +28,16 @@ console.info = function (...args: unknown[]) {
 
 // Track errors by type + JID to avoid duplicates (using Map for better performance)
 const _errorTimestamps = new Map<string, number>()
-const DEDUP_WINDOW_MS = 150
+// Dedup window for repeated decrypt-error console lines (Bad MAC / Counter / etc).
+// Was 150ms, but retry attempts of the SAME message are typically ~300-1000ms apart,
+// so the second attempt fell outside the window and double-printed.
+//
+// TRADE-OFF: dedup key is `errorType + JID` (no message-id). With 5s, a burst of
+// errors for the SAME JID — even of slightly different categories or different
+// messages — collapses to one log line every 5s. This is intentional for a noisy
+// production stream; if you need per-message visibility, set BAILEYS_LOG_LEVEL=debug
+// to bypass this console-side dedup and see the structured pino logs in full.
+const DEDUP_WINDOW_MS = 5000
 
 console.error = function (...args: unknown[]) {
 	if (args.length > 0 && typeof args[0] === 'string') {
@@ -70,7 +79,7 @@ console.error = function (...args: unknown[]) {
 				const lastTime = _errorTimestamps.get(dedupeKey)
 
 				if (lastTime && now - lastTime < DEDUP_WINDOW_MS) {
-					return // Skip duplicate within 150ms window
+					return // Skip duplicate within DEDUP_WINDOW_MS window
 				}
 
 				_errorTimestamps.set(dedupeKey, now)