bug: wallet.transactions() may throw UniFfi::UnexpectedEnumCase due to ChainPosition converter offset accounting #46
Description
Problem
A user reported wallet.transactions() crashing with:
UniFfi::UnexpectedEnumCase at FfiConverterChainPosition.read(...).
Calling wallet.transactions() on a wallet with transaction history can throw while decoding CanonicalTx.chainPosition.
Root cause
In generated Dart bindings, FfiConverterChainPosition (non-flat enum) returned absolute offsets from variant read()/write(), while parent decoders expect relative byte counts.
This causes offset drift when decoding sequences/records from non-zero buffer offsets, eventually corrupting enum tag parsing.
Notes
This appears to be an upstream uniffi-dart codegen issue?
Error
Future<List<Map<String, dynamic>>> getTransactions() async {
print('[TX] Starting getTransactions()');
try {
final results = <Map<String, dynamic>>[];
print('[TX] Fetching canonical transactions from wallet...');
for (final c in wallet.transactions()) { // Throws error
try {
final txid = c.transaction.computeTxid();
print('[TX] OK tx: $txid');
} catch (e) {
print('[TX] Failed decoding canonical tx: $e');
}
}
// print('[TX] Canonical tx count: ${canonical.length}');
List<CanonicalTx> canonical = [];
for (final c in canonical) {
print('[TX] Processing canonical tx...');
final txid = c.transaction.computeTxid();
print('[TX] Computed txid: $txid');
print('[TX] Fetching TxDetails for txid...');
final details = wallet.txDetails(txid);
if (details == null) {
print('[TX][WARN] txDetails returned NULL for $txid');
continue;
}
print('[TX] Converting TxDetails to JSON...');
final json = details.toJson();
results.add(json);
print('[TX] Added tx $txid to results');
}
print('[TX] getTransactions() completed. Total: ${results.length}');
return results;
} catch (e, st) {
print('[TX][ERROR] Failed to fetch transactions');
print('[TX][ERROR] $e');
print('[TX][STACKTRACE]\n$st');
throw Exception('Failed to fetch transactions: $e');
}
}
I/flutter (28298): [TX] Starting getTransactions()
I/flutter (28298): [TX] Fetching canonical transactions from wallet...
I/flutter (28298): [TX][ERROR] Failed to fetch transactions
I/flutter (28298): [TX][ERROR] UniFfi::UnexpectedEnumCase
I/flutter (28298): [TX][STACKTRACE]
I/flutter (28298): #0 FfiConverterChainPosition.read (package:bdk_dart/bdk.dart:5194:9)
I/flutter (28298): #1 FfiConverterCanonicalTx.read (package:bdk_dart/bdk.dart:330:60)
I/flutter (28298): #2 FfiConverterSequenceCanonicalTx.read (package:bdk_dart/bdk.dart:23632:43)
I/flutter (28298): #3 FfiConverterSequenceCanonicalTx.lift (package:bdk_dart/bdk.dart:23624:44)
I/flutter (28298): #4 rustCallWithLifter (package:bdk_dart/bdk.dart:22780:18)
I/flutter (28298): #5 Wallet.transactions (package:bdk_dart/bdk.dart:22526:12)
I/flutter (28298): #6 WalletService.getTransactions (package:flutter_wallet/services/wallet_service.dart:752:30)
I/flutter (28298): #7 WalletPageState._syncWallet (package:flutter_wallet/wallet_pages/wallet_page.dart:340:31)
I/flutter (28298): <asynchronous suspension>
I/flutter (28298): ❌ ERROR DURING SYNC: Exception: Failed to fetch transactions: UniFfi::UnexpectedEnumCase
I/flutter (28298): #0 WalletService.getTransactions (package:flutter_wallet/services/wallet_service.dart:791:7)
I/flutter (28298): #1 WalletPageState._syncWallet (package:flutter_wallet/wallet_pages/wallet_page.dart:340:31)
I/flutter (28298): <asynchronous suspension>
I/flutter (28298): E/flutter (28298): [ERROR:flutter/runtime/dart_vm_initializer.cc(40)] Unhandled Exception: Exception: Sync Error: Exception: Failed to fetch transactions: UniFfi::UnexpectedEnumCase
E/flutter (28298): #0 WalletPageState._syncWallet (package:flutter_wallet/wallet_pages/wallet_page.dart:424:7)
E/flutter (28298): <asynchronous suspension>