Electrum client per wallet refactor

lib/electrumx_rpc/draining_electrum_client.dart

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+import 'dart:async';
+
+import 'package:electrum_adapter/electrum_adapter.dart';
+
+/// A superseded connection finishes its outstanding RPCs before closing.
+/// Every adapter helper, including subscription setup, uses this request hook.
+/// Explicit close still cancels immediately for revocation and shutdown.
+mixin DrainingElectrumClient on ElectrumClient {
+  int _requests = 0;
+  bool _retiring = false;
+
+  Future<void> retire() async {
+    _retiring = true;
+    if (_requests == 0) await close();
+  }
+
+  @override
+  Future<dynamic> requestWithTimeout(
+    String method, {
+    dynamic parameters,
+    Duration? timeout,
+  }) {
+    _requests++;
+    try {
+      final pending = super.requestWithTimeout(
+        method,
+        parameters: parameters,
+        timeout: timeout,
+      );
+      // Keep the original future: subscription setup relies on the adapter's
+      // synchronous completion ordering relative to following notifications.
+      unawaited(
+        pending.then<void>(
+          (_) => _requestFinished(),
+          onError: (Object _) => _requestFinished(),
+        ),
+      );
+      return pending;
+    } catch (_) {
+      _requestFinished();
+      rethrow;
+    }
+  }
+
+  void _requestFinished() {
+    if (--_requests == 0 && _retiring) close().ignore();
+  }
+}
+
+class ManagedElectrumClient extends ElectrumClient with DrainingElectrumClient {
+  ManagedElectrumClient(
+    super.channel,
+    super.host,
+    super.port,
+    super.useSSL,
+    super.proxyInfo, {
+    required super.requestTimeout,
+  });
+}
+
+class ManagedFiroElectrumClient extends FiroElectrumClient
+    with DrainingElectrumClient {
+  ManagedFiroElectrumClient(
+    super.channel,
+    super.host,
+    super.port,
+    super.useSSL,
+    super.proxyInfo, {
+    required super.requestTimeout,
+  });
+}

lib/electrumx_rpc/electrum_request_timeouts.dart

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+/// Response limits shared by individual and batched Electrum requests.
+class ElectrumRequestTimeouts {
+  const ElectrumRequestTimeouts({
+    this.standard = const Duration(seconds: 60),
+    this.history = const Duration(minutes: 5),
+    this.transactionBatch = const Duration(minutes: 5),
+    this.firoSet = const Duration(hours: 3),
+    this.broadcast = const Duration(minutes: 5),
+  });
+
+  final Duration standard;
+  final Duration history;
+
+  /// Deadline for the combined response to a verbose transaction batch.
+  final Duration transactionBatch;
+
+  /// Deadline for a Firo set download. The full Spark used-tag set alone is
+  /// tens of megabytes and arrives as one response, so this is long enough
+  /// for very slow connections to finish it.
+  final Duration firoSet;
+  final Duration broadcast;
+
+  Duration forMethod(String method) => switch (method) {
+    'blockchain.scripthash.get_history' => history,
+    'blockchain.transaction.broadcast' => broadcast,
+    'lelantus.getanonymityset' ||
+    'lelantus.getusedcoinserials' ||
+    'spark.getusedcoinstags' ||
+    'spark.getusedcoinstagstxhashes' ||
+    'spark.getsparkanonymityset' ||
+    'spark.getsparkanonymitysetsector' => firoSet,
+    _ => standard,
+  };
+}