fix: replace magic numbers with RetryReason enum constants

Address remaining Copilot review comments on PR #306:

- Import RetryReason enum from Utils (already re-exported via Utils/index.ts)
- Replace all numeric literals (0/1/2/3/4/7) in retryErrorCode with the
  corresponding enum members (UnknownError / SignalErrorNoSession / etc.)
- Removes inline comments that were only needed to explain magic numbers
- If RetryReason values ever change, the compiler will surface the drift

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

src/Socket/messages-recv.ts

@@ -49,9 +49,12 @@ import {
 	getStatusFromReceiptType,
 	handleIdentityChange,
 	hkdf,
+	BAD_MAC_ERROR_TEXT,
+	DECRYPTION_RETRY_CONFIG,
 	MISSING_KEYS_ERROR_TEXT,
 	NACK_REASONS,
 	NO_MESSAGE_FOUND_ERROR_TEXT,
+	RetryReason,
 	normalizeKeyLidToPn,
 	normalizeMessageJids,
 	resolveLidToPn,
@@ -1213,7 +1216,7 @@ 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!
@@ -1311,39 +1314,39 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 		const { account, signedPreKey, signedIdentityKey: identityKey } = authState.creds
 		const fromJid = node.attrs.from!
 
-		// Check if we should recreate the session
-		let shouldRecreateSession = false
-		let recreateReason = ''
-
-		if (enableAutoSessionRecreation && messageRetryManager && retryCount >= 1) {
-			try {
-				// Check if we have a session with this JID
-				const sessionId = signalRepository.jidToSignalProtocolAddress(fromJid)
-				const hasSession = await signalRepository.validateSession(fromJid)
-
-				// Extract error code from retry node if present (for MAC error detection)
-				const retryNode = getBinaryNodeChild(node, 'retry')
-				const errorAttr = retryNode?.attrs?.error
-				const errorCode = messageRetryManager.parseRetryErrorCode(errorAttr)
-
-				const result = messageRetryManager.shouldRecreateSession(fromJid, hasSession.exists, errorCode)
-				shouldRecreateSession = result.recreate
-				recreateReason = result.reason
-
-				if (shouldRecreateSession) {
-					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')
-			}
-		}
+		// Derive the Signal error code from the actual decryption failure message.
+		// Sent in the retry receipt so the peer (even another InfiniteAPI instance)
+		// knows the exact failure type and can recreate the session immediately
+		// instead of falling back to the 1-hour timeout.
+		//
+		// Codes mirror RetryReason enum in message-retry-manager.ts:
+		//   0 = UnknownError | 1 = NoSession  | 2 = InvalidKey
+		//   3 = InvalidKeyId | 4 = InvalidMessage | 7 = BadMac
+		//
+		// Uses DECRYPTION_RETRY_CONFIG error lists (single source of truth in
+		// decode-wa-message.ts) so additions to those lists are picked up here
+		// automatically.
+		//
+		// NOTE: We do NOT delete the session here (receiver side). The Signal Protocol
+		// recovers automatically when the sender's pkmsg arrives — it overwrites the
+		// corrupted session. Deleting prematurely creates a race window where no session
+		// exists, which can cause "No Session" errors on concurrent messages.
+		const retryErrorCode = (() => {
+			if (!decryptionError) return RetryReason.UnknownError
+			// Bad MAC must be checked first — it is also in corruptedSessionErrors
+			// but warrants the more specific code 7 over the generic code 4.
+			if (decryptionError.includes(BAD_MAC_ERROR_TEXT)) return RetryReason.SignalErrorBadMac
+			// MessageCounterError and other corrupted-session variants
+			if (DECRYPTION_RETRY_CONFIG.corruptedSessionErrors.some(e => decryptionError.includes(e))) return RetryReason.SignalErrorInvalidMessage
+			// Missing / invalid session record
+			if (DECRYPTION_RETRY_CONFIG.sessionRecordErrors.some(e => decryptionError.includes(e)) ||
+				/no\s+(open\s+)?sessions?/i.test(decryptionError)) return RetryReason.SignalErrorNoSession
+			// PreKey / key-id errors
+			if (/pre\s*key/i.test(decryptionError)) return RetryReason.SignalErrorInvalidKeyId
+			// Identity / key errors
+			if (/invalid\s*key|untrusted\s*identity/i.test(decryptionError)) return RetryReason.SignalErrorInvalidKey
+			return RetryReason.UnknownError
+		})()
 
 		if (retryCount <= 2) {
 			// Use new retry manager for phone requests if available
@@ -1384,8 +1387,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 							id: node.attrs.id!,
 							t: node.attrs.t!,
 							v: '1',
-							// ADD ERROR FIELD
-							error: '0'
+							error: retryErrorCode.toString()
 						}
 					},
 					{
@@ -1404,7 +1406,7 @@ 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)
@@ -2507,7 +2509,7 @@ export const makeMessagesRecvSocket = (config: SocketConfig) => {
 							}
 
 							const encNode = getBinaryNodeChild(node, 'enc')
-							await sendRetryRequest(node, !encNode)
+							await sendRetryRequest(node, !encNode, errorMessage)
 							if (retryRequestDelayMs) {
 								await delay(retryRequestDelayMs)
 							}
@@ -2516,7 +2518,7 @@ 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')
 							}