diff --git a/Sources/MRP/Applications/MMRP/MMRPApplication.swift b/Sources/MRP/Applications/MMRP/MMRPApplication.swift
index 97287b40..4c0c4abc 100644
--- a/Sources/MRP/Applications/MMRP/MMRPApplication.swift
+++ b/Sources/MRP/Applications/MMRP/MMRPApplication.swift
@@ -38,34 +38,32 @@ protocol MMRPAwareBridge<P>: Bridge where P: Port {
   ) async throws
 }
 
-public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEventObserver,
-  CustomStringConvertible,
-  Sendable where P == P
+public actor MMRPApplication<P: Port>: BaseApplication, BaseApplicationEventObserver, Sendable,
+  CustomStringConvertible where P == P
 {
   // for now, we only operate in the Base Spanning Tree Context
-  public var nonBaseContextsSupported: Bool { false }
+  public nonisolated var nonBaseContextsSupported: Bool { false }
 
-  public var validAttributeTypes: ClosedRange<AttributeType> {
+  public nonisolated var validAttributeTypes: ClosedRange<AttributeType> {
     MMRPAttributeType.validAttributeTypes
   }
 
   // 10.12.1.3 MMRP application address
-  public var groupAddress: EUI48 { CustomerBridgeMRPGroupAddress }
+  public nonisolated var groupAddress: EUI48 { CustomerBridgeMRPGroupAddress }
 
   // 10.12.1.4 MMRP application EtherType
-  public var etherType: UInt16 { MMRPEtherType }
+  public nonisolated var etherType: UInt16 { MMRPEtherType }
 
   // 10.12.1.5 MMRP ProtocolVersion
-  public var protocolVersion: ProtocolVersion { 0 }
+  public nonisolated var protocolVersion: ProtocolVersion { 0 }
 
-  public var hasAttributeListLength: Bool { false }
+  public nonisolated var hasAttributeListLength: Bool { false }
 
   let _controller: Weak<MRPController<P>>
 
-  public var controller: MRPController<P>? { _controller.object }
+  public nonisolated var controller: MRPController<P>? { _controller.object }
 
-  let _participants =
-    Mutex<[MAPContextIdentifier: Set<Participant<MMRPApplication<P>>>]>([:])
+  var _participants: [MAPContextIdentifier: Set<Participant<MMRPApplication<P>>>] = [:]
   let _logger: Logger
 
   public init(controller: MRPController<P>) async throws {
@@ -74,14 +72,13 @@ public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEve
     try await controller.register(application: self)
   }
 
-  public var description: String {
-    let participants: String = _participants.withLock { String(describing: $0) }
-    return "MMRPApplication(controller: \(controller!), participants: \(participants))"
+  public nonisolated var description: String {
+    "MMRPApplication(controller: \(controller!))"
   }
 
-  public var name: String { "MMRP" }
+  public nonisolated var name: String { "MMRP" }
 
-  public func deserialize(
+  public nonisolated func deserialize(
     attributeOfType attributeType: AttributeType,
     from input: inout ParserSpan
   ) throws -> any Value {
@@ -95,7 +92,7 @@ public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEve
     }
   }
 
-  public func makeNullValue(for attributeType: AttributeType) throws -> any Value {
+  public nonisolated func makeNullValue(for attributeType: AttributeType) throws -> any Value {
     guard let attributeType = MMRPAttributeType(rawValue: attributeType)
     else { throw MRPError.unknownAttributeType }
     switch attributeType {
@@ -106,18 +103,18 @@ public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEve
     }
   }
 
-  public func hasAttributeSubtype(for: AttributeType) -> Bool {
+  public nonisolated func hasAttributeSubtype(for: AttributeType) -> Bool {
     false
   }
 
-  public func administrativeControl(for attributeType: AttributeType) throws
+  public nonisolated func administrativeControl(for attributeType: AttributeType) throws
     -> AdministrativeControl
   {
     .normalParticipant
   }
 
-  public func register(macAddress: EUI48) async throws {
-    try await join(
+  public func register(macAddress: EUI48) throws {
+    try join(
       attributeType: MMRPAttributeType.mac.rawValue,
       attributeValue: MMRPMACValue(macAddress: macAddress),
       isNew: false,
@@ -125,8 +122,8 @@ public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEve
     )
   }
 
-  public func deregister(macAddress: EUI48) async throws {
-    try await leave(
+  public func deregister(macAddress: EUI48) throws {
+    try leave(
       attributeType: MMRPAttributeType.mac.rawValue,
       attributeValue: MMRPMACValue(macAddress: macAddress),
       for: MAPBaseSpanningTreeContext
@@ -135,8 +132,8 @@ public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEve
 
   public func register(
     serviceRequirement requirementSpecification: MMRPServiceRequirementValue
-  ) async throws {
-    try await join(
+  ) throws {
+    try join(
       attributeType: MMRPAttributeType.serviceRequirement.rawValue,
       attributeValue: requirementSpecification,
       isNew: false,
@@ -146,8 +143,8 @@ public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEve
 
   public func deregister(
     serviceRequirement requirementSpecification: MMRPServiceRequirementValue
-  ) async throws {
-    try await leave(
+  ) throws {
+    try leave(
       attributeType: MMRPAttributeType.serviceRequirement.rawValue,
       attributeValue: requirementSpecification,
       for: MAPBaseSpanningTreeContext
@@ -155,8 +152,8 @@ public final class MMRPApplication<P: Port>: BaseApplication, BaseApplicationEve
   }
 
   public func periodic(for contextIdentifier: MAPContextIdentifier? = nil) async throws {
-    try await apply(for: contextIdentifier) { participant in
-      try await participant.periodic()
+    try apply(for: contextIdentifier) { participant in
+      try participant.periodic()
     }
   }
 }
diff --git a/Sources/MRP/Applications/MSRP/MSRPApplication.swift b/Sources/MRP/Applications/MSRP/MSRPApplication.swift
index b7263865..2460c576 100644
--- a/Sources/MRP/Applications/MSRP/MSRPApplication.swift
+++ b/Sources/MRP/Applications/MSRP/MSRPApplication.swift
@@ -137,32 +137,31 @@ struct MSRPPortState<P: AVBPort>: Sendable {
   }
 }
 
-public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplicationEventObserver,
-  BaseApplicationContextObserver, CustomStringConvertible, @unchecked Sendable where P == P
+public actor MSRPApplication<P: AVBPort>: BaseApplication, BaseApplicationEventObserver, Sendable,
+  BaseApplicationContextObserver, CustomStringConvertible where P == P
 {
   private typealias TalkerRegistration = (Participant<MSRPApplication>, any MSRPTalkerValue)
 
   // for now, we only operate in the Base Spanning Tree Context
-  public var nonBaseContextsSupported: Bool { false }
+  public nonisolated var nonBaseContextsSupported: Bool { false }
 
-  public var validAttributeTypes: ClosedRange<AttributeType> {
+  public nonisolated var validAttributeTypes: ClosedRange<AttributeType> {
     MSRPAttributeType.validAttributeTypes
   }
 
-  public var groupAddress: EUI48 { IndividualLANScopeGroupAddress }
+  public nonisolated var groupAddress: EUI48 { IndividualLANScopeGroupAddress }
 
-  public var etherType: UInt16 { MSRPEtherType }
+  public nonisolated var etherType: UInt16 { MSRPEtherType }
 
-  public var protocolVersion: ProtocolVersion { MSRPProtocolVersion.v0.rawValue }
+  public nonisolated var protocolVersion: ProtocolVersion { MSRPProtocolVersion.v0.rawValue }
 
-  public var hasAttributeListLength: Bool { true }
+  public nonisolated var hasAttributeListLength: Bool { true }
 
   let _controller: Weak<MRPController<P>>
 
-  public var controller: MRPController<P>? { _controller.object }
+  public nonisolated var controller: MRPController<P>? { _controller.object }
 
-  let _participants =
-    Mutex<[MAPContextIdentifier: Set<Participant<MSRPApplication<P>>>]>([:])
+  var _participants: [MAPContextIdentifier: Set<Participant<MSRPApplication<P>>>] = [:]
   let _logger: Logger
   let _latencyMaxFrameSize: UInt16
   let _queues: [SRclassID: UInt]
@@ -174,15 +173,15 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
 
   fileprivate let _maxFanInPorts: Int
   fileprivate let _maxSRClass: SRclassID
-  fileprivate let _portStates = Mutex<[P.ID: MSRPPortState<P>]>([:])
+  fileprivate var _portStates: [P.ID: MSRPPortState<P>] = [:]
   fileprivate let _mmrp: MMRPApplication<P>?
   fileprivate var _priorityMapNotificationTask: Task<(), Error>?
 
   // Convenience accessors for flags
-  fileprivate var _forceAvbCapable: Bool { _flags.contains(.forceAvbCapable) }
-  fileprivate var _configureQueues: Bool { _flags.contains(.configureQueues) }
-  var _ignoreAsCapable: Bool { _flags.contains(.ignoreAsCapable) }
-  fileprivate var _talkerPruning: Bool { _flags.contains(.talkerPruning) }
+  fileprivate nonisolated var _forceAvbCapable: Bool { _flags.contains(.forceAvbCapable) }
+  fileprivate nonisolated var _configureQueues: Bool { _flags.contains(.configureQueues) }
+  nonisolated var _ignoreAsCapable: Bool { _flags.contains(.ignoreAsCapable) }
+  fileprivate nonisolated var _talkerPruning: Bool { _flags.contains(.talkerPruning) }
 
   public init(
     controller: MRPController<P>,
@@ -228,12 +227,10 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
     port: P,
     _ body: (_: inout MSRPPortState<P>) throws -> T
   ) throws -> T {
-    try _portStates.withLock {
-      if let index = $0.index(forKey: port.id) {
-        return try body(&$0.values[index])
-      } else {
-        throw MRPError.portNotFound
-      }
+    if let index = _portStates.index(forKey: port.id) {
+      return try body(&_portStates.values[index])
+    } else {
+      throw MRPError.portNotFound
     }
   }
 
@@ -276,85 +273,73 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
       }
     }
 
-    try _portStates.withLock {
-      for port in context {
-        var portState = try MSRPPortState(msrp: self, port: port)
-        if let srClassPriorityMap = srClassPriorityMap[port.id] {
-          portState.srClassPriorityMap = srClassPriorityMap
-        }
-        $0[port.id] = portState
+    for port in context {
+      var portState = try MSRPPortState(msrp: self, port: port)
+      if let srClassPriorityMap = srClassPriorityMap[port.id] {
+        portState.srClassPriorityMap = srClassPriorityMap
       }
+      _portStates[port.id] = portState
     }
 
     for port in context {
       _logger.debug("MSRP: declaring domains for port \(port)")
-      try await _declareDomains(port: port)
+      try _declareDomains(port: port)
     }
   }
 
   func onContextUpdated(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {
+  ) async throws {
     guard contextIdentifier == MAPBaseSpanningTreeContext else { return }
 
     if !_forceAvbCapable {
-      _portStates.withLock {
-        for port in context {
-          guard let index = $0.index(forKey: port.id) else { continue }
-          if $0.values[index].msrpPortEnabledStatus != port.isAvbCapable {
-            _logger.info("MSRP: port \(port) changed isAvbCapable, now \(port.isAvbCapable)")
-          }
-          $0.values[index].msrpPortEnabledStatus = port.isAvbCapable
+      for port in context {
+        guard let index = _portStates.index(forKey: port.id) else { continue }
+        if _portStates.values[index].msrpPortEnabledStatus != port.isAvbCapable {
+          _logger.info("MSRP: port \(port) changed isAvbCapable, now \(port.isAvbCapable)")
         }
+        _portStates.values[index].msrpPortEnabledStatus = port.isAvbCapable
       }
     }
 
-    Task {
-      for port in context {
-        _logger.debug("MSRP: re-declaring domains for port \(port)")
-        try await _declareDomains(port: port)
-      }
+    for port in context {
+      _logger.debug("MSRP: re-declaring domains for port \(port)")
+      try _declareDomains(port: port)
     }
   }
 
   func onContextRemoved(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {
+  ) async throws {
     guard contextIdentifier == MAPBaseSpanningTreeContext else { return }
 
     if _configureQueues {
-      Task {
-        for port in context {
-          guard port.isAvbCapable,
-                let bridge = (controller?.bridge as? any MSRPAwareBridge<P>) else { continue }
-          do {
-            try await bridge.unconfigureQueues(port: port)
-          } catch {
-            _logger.error("MSRP: failed to unconfigure queues for port \(port): \(error)")
-          }
+      for port in context {
+        guard port.isAvbCapable,
+              let bridge = (controller?.bridge as? any MSRPAwareBridge<P>) else { continue }
+        do {
+          try await bridge.unconfigureQueues(port: port)
+        } catch {
+          _logger.error("MSRP: failed to unconfigure queues for port \(port): \(error)")
         }
       }
     }
 
-    _portStates.withLock {
-      for port in context {
-        _logger.debug("MSRP: port \(port) disappeared, removing")
-        $0.removeValue(forKey: port.id)
-      }
+    for port in context {
+      _logger.debug("MSRP: port \(port) disappeared, removing")
+      _portStates.removeValue(forKey: port.id)
     }
   }
 
-  public var description: String {
-    let participants: String = _participants.withLock { String(describing: $0) }
-    let portStates: String = _portStates.withLock { String(describing: $0) }
-    return "MSRPApplication(controller: \(controller?.description ?? "<nil>"), participants: \(participants), portStates: \(portStates)"
+  public nonisolated var description: String {
+    "MSRPApplication(controller: \(controller!))"
   }
 
-  public var name: String { "MSRP" }
+  public nonisolated var name: String { "MSRP" }
 
-  public func deserialize(
+  public nonisolated func deserialize(
     attributeOfType attributeType: AttributeType,
     from input: inout ParserSpan
   ) throws -> any Value {
@@ -372,7 +357,7 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
     }
   }
 
-  public func makeNullValue(for attributeType: AttributeType) throws -> any Value {
+  public nonisolated func makeNullValue(for attributeType: AttributeType) throws -> any Value {
     guard let attributeType = MSRPAttributeType(rawValue: attributeType)
     else { throw MRPError.unknownAttributeType }
     switch attributeType {
@@ -387,11 +372,11 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
     }
   }
 
-  public func hasAttributeSubtype(for attributeType: AttributeType) -> Bool {
+  public nonisolated func hasAttributeSubtype(for attributeType: AttributeType) -> Bool {
     attributeType == MSRPAttributeType.listener.rawValue
   }
 
-  public func administrativeControl(for attributeType: AttributeType) throws
+  public nonisolated func administrativeControl(for attributeType: AttributeType) throws
     -> AdministrativeControl
   {
     .normalParticipant
@@ -411,7 +396,7 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
     priorityAndRank: MSRPPriorityAndRank,
     accumulatedLatency: UInt32,
     failureInformation: MSRPFailure? = nil
-  ) async throws {
+  ) throws {
     let attributeValue: any Value
 
     switch declarationType {
@@ -447,7 +432,7 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
       throw MRPError.invalidMSRPDeclarationType
     }
 
-    try await join(
+    try join(
       attributeType: (
         failureInformation != nil ? MSRPAttributeType.talkerFailed : MSRPAttributeType
           .talkerAdvertise
@@ -465,8 +450,8 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
   // were in the associated REGISTER_STREAM.request primitive.
   public func deregisterStream(
     streamID: MSRPStreamID
-  ) async throws {
-    guard let talkerRegistration = await _findTalkerRegistration(for: streamID) else {
+  ) throws {
+    guard let talkerRegistration = _findTalkerRegistration(for: streamID) else {
       throw MRPError.participantNotFound
     }
     let declarationType: MSRPDeclarationType = if talkerRegistration.1 is MSRPTalkerAdvertiseValue {
@@ -474,7 +459,7 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
     } else {
       .talkerFailed
     }
-    try await leave(
+    try leave(
       attributeType: declarationType.attributeType.rawValue,
       attributeValue: MSRPListenerValue(streamID: streamID),
       for: MAPBaseSpanningTreeContext
@@ -490,10 +475,10 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
     streamID: MSRPStreamID,
     declarationType: MSRPDeclarationType,
     on port: P? = nil
-  ) async throws {
-    try await apply { participant in
+  ) throws {
+    try apply { participant in
       if let port, port != participant.port { return }
-      try await join(
+      try join(
         attributeType: MSRPAttributeType.listener.rawValue,
         attributeSubtype: declarationType.attributeSubtype?.rawValue,
         attributeValue: MSRPListenerValue(streamID: streamID),
@@ -511,16 +496,16 @@ public final class MSRPApplication<P: AVBPort>: BaseApplication, BaseApplication
   public func deregisterAttach(
     streamID: MSRPStreamID,
     on port: P? = nil
-  ) async throws {
-    try await apply { participant in
+  ) throws {
+    try apply { participant in
       if let port, port != participant.port { return }
 
-      guard let listenerRegistration = await _findListenerRegistration(
+      guard let listenerRegistration = _findListenerRegistration(
         for: streamID,
         participant: participant
       ) else { return }
 
-      try await leave(
+      try leave(
         attributeType: MSRPAttributeType.listener.rawValue,
         attributeSubtype: listenerRegistration.1.rawValue,
         attributeValue: listenerRegistration.0,
@@ -542,24 +527,24 @@ extension MSRPApplication {
     declarationType: MSRPDeclarationType,
     streamID: MSRPStreamID,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     let oppositeType: MSRPAttributeType = declarationType == .talkerAdvertise ? .talkerFailed :
       .talkerAdvertise
 
-    let oppositeAttributes = await participant.findAttributes(
+    let oppositeAttributes = participant.findAttributes(
       attributeType: oppositeType.rawValue,
       matching: .matchAnyIndex(streamID.index)
     )
 
     for (_, attributeValue) in oppositeAttributes {
       if eventSource == .map {
-        try? await participant.leave(
+        try? participant.leave(
           attributeType: oppositeType.rawValue,
           attributeValue: attributeValue,
           eventSource: eventSource
         )
       } else {
-        try? await participant.deregister(
+        try? participant.deregister(
           attributeType: oppositeType.rawValue,
           attributeValue: attributeValue,
           eventSource: eventSource
@@ -582,8 +567,8 @@ extension MSRPApplication {
     guard let portState = try? withPortState(port: port, { $0 }) else { return true }
 
     if _talkerPruning || portState.talkerPruning {
-      if let mmrpParticipant = try? _mmrp?.findParticipant(port: port),
-         await mmrpParticipant.findAttribute(
+      if let mmrpParticipant = try? await _mmrp?.findParticipant(port: port),
+         mmrpParticipant.findAttribute(
            attributeType: MMRPAttributeType.mac.rawValue,
            matching: .matchEqual(MMRPMACValue(macAddress: dataFrameParameters.destinationAddress))
          ) == nil
@@ -599,7 +584,7 @@ extension MSRPApplication {
     return false
   }
 
-  private func _isFanInPortLimitReached() async -> Bool {
+  private func _isFanInPortLimitReached() -> Bool {
     if _maxFanInPorts == 0 {
       return false
     }
@@ -607,8 +592,8 @@ extension MSRPApplication {
     var fanInCount = 0
 
     // calculate total number of ports with inbound reservations
-    await apply { participant in
-      if await participant.findAttribute(
+    apply { participant in
+      if participant.findAttribute(
         attributeType: MSRPAttributeType.listener.rawValue,
         matching: .matchAny
       ) != nil {
@@ -707,11 +692,11 @@ extension MSRPApplication {
     participant: Participant<MSRPApplication>,
     portState: MSRPPortState<P>,
     provisionalTalker: MSRPTalkerAdvertiseValue? = nil
-  ) async throws -> [SRclassID: Int] {
+  ) throws -> [SRclassID: Int] {
     var bandwidthUsed = [SRclassID: Int]()
 
     // Find all active talkers (those with listeners in ready or readyFailed state)
-    var talkers = await _findActiveTalkers(participant: participant)
+    var talkers = _findActiveTalkers(participant: participant)
 
     // Add provisional talker if provided (for bandwidth admission control check)
     if let provisionalTalker { talkers.insert(provisionalTalker) }
@@ -744,7 +729,7 @@ extension MSRPApplication {
     dataFrameParameters: MSRPDataFrameParameters,
     tSpec: MSRPTSpec,
     priorityAndRank: MSRPPriorityAndRank
-  ) async throws -> Bool {
+  ) throws -> Bool {
     let port = participant.port
     let provisionalTalker = MSRPTalkerAdvertiseValue(
       streamID: streamID,
@@ -754,7 +739,7 @@ extension MSRPApplication {
       accumulatedLatency: 0 // or this
     )
 
-    let bandwidthUsed = try await _calculateBandwidthUsed(
+    let bandwidthUsed = try _calculateBandwidthUsed(
       participant: participant,
       portState: portState,
       provisionalTalker: provisionalTalker
@@ -789,7 +774,7 @@ extension MSRPApplication {
     accumulatedLatency: UInt32,
     isNew: Bool,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     let port = participant.port
 
     do {
@@ -802,7 +787,7 @@ extension MSRPApplication {
         throw MSRPFailure(systemID: port.systemID, failureCode: .egressPortIsNotAvbCapable)
       }
 
-      if let existingTalkerRegistration = await _findTalkerRegistration(
+      if let existingTalkerRegistration = _findTalkerRegistration(
         for: streamID,
         participant: participant
       ), existingTalkerRegistration.dataFrameParameters != dataFrameParameters {
@@ -822,7 +807,7 @@ extension MSRPApplication {
         throw MSRPFailure(systemID: port.systemID, failureCode: .egressPortIsNotAvbCapable)
       }
 
-      guard await !_isFanInPortLimitReached() else {
+      guard !_isFanInPortLimitReached() else {
         _logger.error("MSRP: fan in port limit reached")
         throw MSRPFailure(systemID: port.systemID, failureCode: .fanInPortLimitReached)
       }
@@ -839,7 +824,7 @@ extension MSRPApplication {
         throw MSRPFailure(systemID: port.systemID, failureCode: .maxFrameSizeTooLargeForMedia)
       }
 
-      guard try await _checkAvailableBandwidth(
+      guard try _checkAvailableBandwidth(
         participant: participant,
         portState: portState,
         streamID: streamID,
@@ -890,7 +875,7 @@ extension MSRPApplication {
     // Deregister the opposite talker type from the peer to ensure mutual exclusion
     if eventSource == .peer {
       let sourceParticipant = try findParticipant(for: contextIdentifier, port: port)
-      try await _enforceTalkerMutualExclusion(
+      try _enforceTalkerMutualExclusion(
         participant: sourceParticipant,
         declarationType: declarationType,
         streamID: talkerValue.streamID,
@@ -938,7 +923,7 @@ extension MSRPApplication {
 
       // Leave the opposite talker declaration type to ensure mutual exclusion
       // (per spec, only one talker declaration type should exist per stream)
-      try await _enforceTalkerMutualExclusion(
+      try _enforceTalkerMutualExclusion(
         participant: participant,
         declarationType: declarationType,
         streamID: talkerValue.streamID,
@@ -947,7 +932,7 @@ extension MSRPApplication {
 
       if declarationType == .talkerAdvertise {
         do {
-          try await _canBridgeTalker(
+          try _canBridgeTalker(
             participant: participant,
             port: port,
             streamID: talkerValue.streamID,
@@ -970,7 +955,7 @@ extension MSRPApplication {
             .debug(
               "MSRP: propagating talker advertise \(talkerAdvertise) to port \(port)"
             )
-          try await participant.join(
+          try participant.join(
             attributeType: MSRPAttributeType.talkerAdvertise.rawValue,
             attributeValue: talkerAdvertise,
             isNew: false,
@@ -990,7 +975,7 @@ extension MSRPApplication {
             .debug(
               "MSRP: propagating talker failed \(talkerFailed) on port \(port), error \(error)"
             )
-          try await participant.join(
+          try participant.join(
             attributeType: MSRPAttributeType.talkerFailed.rawValue,
             attributeValue: talkerFailed,
             isNew: true,
@@ -1012,7 +997,7 @@ extension MSRPApplication {
           .debug(
             "MSRP: propagating talker failed \(talkerFailed) to port \(port), transitive"
           )
-        try await participant.join(
+        try participant.join(
           attributeType: MSRPAttributeType.talkerFailed.rawValue,
           attributeValue: talkerFailed,
           isNew: false,
@@ -1042,7 +1027,7 @@ extension MSRPApplication {
     // _propagateListenerDeclarationToTalker() will examine all listeners and
     // return the merged declaration type, so there is no need to do this
     // within the apply() loop
-    guard let mergedDeclarationType = try? await _propagateListenerDeclarationToTalker(
+    guard let mergedDeclarationType = try? _propagateListenerDeclarationToTalker(
       contextIdentifier: contextIdentifier,
       listenerPort: nil,
       declarationType: nil,
@@ -1056,7 +1041,7 @@ extension MSRPApplication {
     // that didn't exist previously, we do need to update port parameters on
     // each talker port that matches the listener stream ID
     await apply(for: contextIdentifier) { participant in
-      guard let listenerRegistration = await _findListenerRegistration(
+      guard let listenerRegistration = _findListenerRegistration(
         for: talkerValue.streamID,
         participant: participant
       ) else {
@@ -1064,7 +1049,7 @@ extension MSRPApplication {
       }
 
       // verify talker still exists (guard against race with talker departure)
-      guard let currentTalker = await _findTalkerRegistration(
+      guard let currentTalker = _findTalkerRegistration(
         for: talkerValue.streamID,
         participant: talkerParticipant
       ), currentTalker.streamID == talkerValue.streamID else {
@@ -1135,8 +1120,8 @@ extension MSRPApplication {
   private func _findListenerRegistration(
     for streamID: MSRPStreamID,
     participant: Participant<MSRPApplication>
-  ) async -> (MSRPListenerValue, MSRPAttributeSubtype)? {
-    guard let listenerAttribute = await participant.findAttribute(
+  ) -> (MSRPListenerValue, MSRPAttributeSubtype)? {
+    guard let listenerAttribute = participant.findAttribute(
       attributeType: MSRPAttributeType.listener.rawValue,
       matching: .matchAnyIndex(streamID.index)
     ) else { return nil }
@@ -1154,14 +1139,14 @@ extension MSRPApplication {
   private func _findTalkerRegistration(
     for streamID: MSRPStreamID,
     participant: Participant<MSRPApplication>
-  ) async -> (any MSRPTalkerValue)? {
+  ) -> (any MSRPTalkerValue)? {
     // TalkerFailed takes precedence over TalkerAdvertise per spec
-    if let value = await participant.findAttribute(
+    if let value = participant.findAttribute(
       attributeType: MSRPAttributeType.talkerFailed.rawValue,
       matching: .matchAnyIndex(streamID.index)
     ) {
       value.1 as? (any MSRPTalkerValue)
-    } else if let value = await participant.findAttribute(
+    } else if let value = participant.findAttribute(
       attributeType: MSRPAttributeType.talkerAdvertise.rawValue,
       matching: .matchAnyIndex(streamID.index)
     ) {
@@ -1173,11 +1158,11 @@ extension MSRPApplication {
 
   private func _findTalkerRegistration(
     for streamID: MSRPStreamID
-  ) async -> TalkerRegistration? {
+  ) -> TalkerRegistration? {
     var talkerRegistration: TalkerRegistration?
 
-    await apply { participant in
-      guard let participantTalker = await _findTalkerRegistration(
+    apply { participant in
+      guard let participantTalker = _findTalkerRegistration(
         for: streamID,
         participant: participant
       ), talkerRegistration == nil else {
@@ -1195,22 +1180,23 @@ extension MSRPApplication {
     declarationType: MSRPDeclarationType?,
     talkerRegistration: TalkerRegistration,
     isJoin: Bool
-  ) async throws -> MSRPDeclarationType? {
+  ) throws -> MSRPDeclarationType? {
     var mergedDeclarationType = isJoin ? declarationType : nil
     let streamID = talkerRegistration.1.streamID
     var listenerCount = mergedDeclarationType != nil ? 1 : 0
 
     // collect listener declarations from all other ports and merge declaration type
-    await apply(for: contextIdentifier) { participant in
+    apply(for: contextIdentifier) { participant in
       // exclude registering or leaving port
       guard participant.port != port else { return }
 
       // exclude talker port
       guard participant.port != talkerRegistration.0.port else { return }
 
-      for listenerAttribute in await participant.findAllAttributes(
+      for listenerAttribute in participant.findAllAttributesUnchecked(
         attributeType: MSRPAttributeType.listener.rawValue,
-        matching: .matchAnyIndex(streamID.id)
+        matching: .matchAnyIndex(streamID.id),
+        isolation: self
       ) {
         guard let declarationType = try? MSRPDeclarationType(attributeSubtype: listenerAttribute
           .attributeSubtype)
@@ -1275,19 +1261,19 @@ extension MSRPApplication {
 
   private func _findActiveTalkers(
     participant: Participant<MSRPApplication<P>>
-  ) async -> Set<MSRPTalkerAdvertiseValue> {
+  ) -> Set<MSRPTalkerAdvertiseValue> {
     // Find all active talkers by querying listeners on this port and finding their corresponding
     // talkers
-    await Set(participant.findAttributes(
+    Set(participant.findAttributes(
       attributeType: MSRPAttributeType.listener.rawValue,
       matching: .matchAny
-    ).asyncCompactMap {
+    ).compactMap {
       guard let attributeSubtype = $0.0,
             let attributeSubtype = MSRPAttributeSubtype(rawValue: attributeSubtype),
             attributeSubtype == .ready || attributeSubtype == .readyFailed else { return nil }
 
       let listener = $0.1 as! MSRPListenerValue
-      guard let talkerRegistration = await _findTalkerRegistration(for: listener.streamID),
+      guard let talkerRegistration = _findTalkerRegistration(for: listener.streamID),
             let talkerAdvertise = talkerRegistration.1 as? MSRPTalkerAdvertiseValue
       else { return nil }
       return talkerAdvertise
@@ -1310,7 +1296,7 @@ extension MSRPApplication {
       return
     }
 
-    var talkers = await _findActiveTalkers(participant: participant)
+    var talkers = _findActiveTalkers(participant: participant)
 
     // Remove the specific talker stream that is the subject of this
     // registration or deregistration; we will add it back conditionally
@@ -1417,7 +1403,7 @@ extension MSRPApplication {
     isNew: Bool,
     eventSource: EventSource,
     talkerRegistration: TalkerRegistration
-  ) async throws -> MSRPDeclarationType? {
+  ) throws -> MSRPDeclarationType? {
     // point-to-point talker registrations should not come from the same port as the listener
     if let port, port.isPointToPoint, talkerRegistration.0.port == port {
       _logger
@@ -1428,7 +1414,7 @@ extension MSRPApplication {
     }
 
     // TL;DR: propagate merged Listener declarations to _talker_ port
-    guard let mergedDeclarationType = try await _mergeListenerDeclarations(
+    guard let mergedDeclarationType = try _mergeListenerDeclarations(
       contextIdentifier: contextIdentifier,
       port: port,
       declarationType: declarationType,
@@ -1443,7 +1429,7 @@ extension MSRPApplication {
         "MSRP: propagating listener declaration streamID \(streamID) declarationType \(declarationType != nil ? String(describing: declarationType!) : "<nil>") -> \(mergedDeclarationType) to participant \(talkerRegistration.0)"
       )
 
-    try await talkerRegistration.0.join(
+    try talkerRegistration.0.join(
       attributeType: MSRPAttributeType.listener.rawValue,
       attributeSubtype: mergedDeclarationType.attributeSubtype!.rawValue,
       attributeValue: MSRPListenerValue(streamID: streamID),
@@ -1467,7 +1453,7 @@ extension MSRPApplication {
     isNew: Bool,
     eventSource: EventSource
   ) async throws {
-    guard let talkerRegistration = await _findTalkerRegistration(for: streamID) else {
+    guard let talkerRegistration = _findTalkerRegistration(for: streamID) else {
       // no listener attribute propagation if no talker (35.2.4.4.1)
       // this is an expected race condition - listener arrives before talker
       // when talker arrives, _updateExistingListeners() will process it
@@ -1478,7 +1464,7 @@ extension MSRPApplication {
       return
     }
 
-    guard let mergedDeclarationType = try await _propagateListenerDeclarationToTalker(
+    guard let mergedDeclarationType = try _propagateListenerDeclarationToTalker(
       contextIdentifier: contextIdentifier,
       listenerPort: port,
       declarationType: declarationType,
@@ -1606,11 +1592,11 @@ extension MSRPApplication {
       guard participant.port != port else { return } // don't propagate to source port
 
       // If this participant has active listeners, propagate a leave back to the talker
-      if let listenerRegistration = await _findListenerRegistration(
+      if let listenerRegistration = _findListenerRegistration(
         for: streamID,
         participant: participant
       ) {
-        try await talkerParticipant.leave(
+        try talkerParticipant.leave(
           attributeType: MSRPAttributeType.listener.rawValue,
           attributeSubtype: listenerRegistration.1.rawValue,
           attributeValue: listenerRegistration.0,
@@ -1628,7 +1614,7 @@ extension MSRPApplication {
       // 35.2.4.3: If no Talker attributes are registered for a StreamID then
       // no Talker attributes for that StreamID will be declared on any other
       // port of the Bridge. i.e. implement as ordinary attribute propagation
-      try await participant.leave(
+      try participant.leave(
         attributeType: talkerValue.declarationType!.attributeType.rawValue,
         attributeSubtype: nil,
         attributeValue: talkerValue,
@@ -1651,12 +1637,12 @@ extension MSRPApplication {
     // StreamID of the Declaration matches a Stream that the Talker is
     // transmitting, then the Talker shall stop the transmission for this
     // Stream, if it is transmitting.
-    guard let talkerRegistration = await _findTalkerRegistration(for: streamID) else {
+    guard let talkerRegistration = _findTalkerRegistration(for: streamID) else {
       return
     }
 
     // TL;DR: propagate merged Listener declarations to _talker_ port
-    let mergedDeclarationType = try await _mergeListenerDeclarations(
+    let mergedDeclarationType = try _mergeListenerDeclarations(
       contextIdentifier: contextIdentifier,
       port: port,
       declarationType: declarationType,
@@ -1670,7 +1656,7 @@ extension MSRPApplication {
       )
 
     if let mergedDeclarationType {
-      try await talkerRegistration.0.join(
+      try talkerRegistration.0.join(
         attributeType: MSRPAttributeType.listener.rawValue,
         attributeSubtype: mergedDeclarationType.attributeSubtype!.rawValue,
         attributeValue: MSRPListenerValue(streamID: streamID),
@@ -1678,7 +1664,7 @@ extension MSRPApplication {
         eventSource: .map
       )
     } else {
-      try await talkerRegistration.0.leave(
+      try talkerRegistration.0.leave(
         attributeType: MSRPAttributeType.listener.rawValue,
         attributeValue: MSRPListenerValue(streamID: streamID),
         eventSource: .map
@@ -1756,7 +1742,7 @@ extension MSRPApplication {
   private func _declareDomain(
     srClassID: SRclassID,
     on participant: Participant<MSRPApplication>
-  ) async throws {
+  ) throws {
     var domain: MSRPDomainValue?
 
     domain = try withPortState(port: participant.port) { portState in
@@ -1765,7 +1751,7 @@ extension MSRPApplication {
 
     if let domain {
       _logger.info("MSRP: declaring domain \(domain)")
-      try await participant.join(
+      try participant.join(
         attributeType: MSRPAttributeType.domain.rawValue,
         attributeValue: domain,
         isNew: true,
@@ -1779,14 +1765,14 @@ extension MSRPApplication {
     }
   }
 
-  fileprivate var _allSRClassIDs: [SRclassID] {
+  fileprivate nonisolated var _allSRClassIDs: [SRclassID] {
     Array((_maxSRClass.rawValue...SRclassID.A.rawValue).map { SRclassID(rawValue: $0)! })
   }
 
-  private func _declareDomains(port: P) async throws {
+  private func _declareDomains(port: P) throws {
     let participant = try findParticipant(port: port)
     for srClassID in _allSRClassIDs {
-      try await _declareDomain(srClassID: srClassID, on: participant)
+      try _declareDomain(srClassID: srClassID, on: participant)
     }
   }
 
@@ -1794,13 +1780,13 @@ extension MSRPApplication {
     get async {
       var numberOfTalkerAttributes = 0
 
-      await apply { participant in
-        numberOfTalkerAttributes += await participant.findAttributes(
+      apply { participant in
+        numberOfTalkerAttributes += participant.findAttributes(
           attributeType: MSRPAttributeType.talkerAdvertise.rawValue,
           matching: .matchAny
         ).count
 
-        numberOfTalkerAttributes += await participant.findAttributes(
+        numberOfTalkerAttributes += participant.findAttributes(
           attributeType: MSRPAttributeType.talkerFailed.rawValue,
           matching: .matchAny
         ).count
diff --git a/Sources/MRP/Applications/MSRP/MSRPHandler.swift b/Sources/MRP/Applications/MSRP/MSRPHandler.swift
index c214217e..0a81f14b 100644
--- a/Sources/MRP/Applications/MSRP/MSRPHandler.swift
+++ b/Sources/MRP/Applications/MSRP/MSRPHandler.swift
@@ -133,9 +133,9 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
       participant: Participant<Application>,
       srClassID: SRclassID,
       streams: [Stream]
-    ) {
+    ) async {
       deltaBandwidth = application._deltaBandwidths[srClassID] ?? 0
-      guard let portState = try? application.withPortState(port: participant.port, { $0 })
+      guard let portState = try? await application.withPortState(port: participant.port, { $0 })
       else { return nil }
       guard let domain = portState.getDomain(for: srClassID, defaultSRPVid: application._srPVid)
       else { return nil }
@@ -176,7 +176,10 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
       let type: String
       let streamAge: UInt32
 
-      fileprivate init(participant: Participant<Application>, attributeValue: AttributeValue) {
+      fileprivate init(
+        participant: Participant<Application>,
+        attributeValue: AttributeValue
+      ) async {
         portNumber = participant.port.id
         portName = participant.port.name
 
@@ -200,7 +203,7 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
         let streamID = (attributeValue.attributeValue as! MSRPListenerValue).streamID
 
         streamAge = if let application = participant.application {
-          (try? application
+          await (try? application
             .withPortState(port: participant.port) { $0.getStreamAge(for: streamID) }) ?? 0
         } else {
           0
@@ -223,13 +226,13 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
       attributeValue: AttributeValue
     ) async throws {
       let talker = attributeValue.attributeValue as! any MSRPTalkerValue
-      let portState = try application.withPortState(port: participant.port) { $0 }
+      let portState = try await application.withPortState(port: participant.port) { $0 }
 
       streamID = talker.streamID.streamIDString
       vid = talker.dataFrameParameters.vlanIdentifier.vid
       priority = talker.priorityAndRank.dataFramePriority.rawValue
       if let talker = talker as? MSRPTalkerAdvertiseValue {
-        bandwidth = try application._calculateBandwidthUsed(
+        bandwidth = try await application._calculateBandwidthUsed(
           portState: portState,
           talker: talker,
           nominalBandwidth: false
@@ -262,15 +265,15 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
       let port = participant.port
       let streams = await application._getStreams()
 
-      enabled = (try? application
+      enabled = await (try? application
         .withPortState(port: participant.port) { $0.msrpPortEnabledStatus }) ?? false
       listener = await participant._getListeners()
       talker = await participant._getTalkers()
       talkerFailed = await participant._getTalkersFailed()
       let activeStreamIDs = Set(listener.map(\.streamID))
       let activeStreams = streams.filter { activeStreamIDs.contains($0.streamID) }
-      srClass = SRclassID.allCases.reduce(into: [:]) { dict, classID in
-        if let srClassInstance = SRClass(
+      srClass = await SRclassID.allCases.asyncReduce(into: [:]) { dict, classID in
+        if let srClassInstance = await SRClass(
           application: application,
           participant: participant,
           srClassID: classID,
@@ -364,7 +367,7 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
   func getListenerByStreamID(_ request: HTTPRequest) async throws -> Listener {
     guard let application,
           let (port, streamID) = await application._getPortAndStream(request),
-          let participant = try? application.findParticipant(port: port)
+          let participant = try? await application.findParticipant(port: port)
     else {
       throw HTTPUnhandledError()
     }
@@ -531,7 +534,7 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
   func getTalker(_ request: HTTPRequest) async throws -> Array<Talker> {
     guard let application,
           let port = await controller?.getPort(request),
-          let participant = try? application.findParticipant(port: port.0)
+          let participant = try? await application.findParticipant(port: port.0)
     else {
       throw HTTPUnhandledError()
     }
@@ -546,7 +549,7 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
   func getTalkerByStreamID(_ request: HTTPRequest) async throws -> Talker {
     guard let application,
           let (port, streamID) = await application._getPortAndStream(request),
-          let participant = try? application.findParticipant(port: port)
+          let participant = try? await application.findParticipant(port: port)
     else {
       throw HTTPUnhandledError()
     }
@@ -565,7 +568,7 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
   func getTalkerFailed(_ request: HTTPRequest) async throws -> Array<TalkerFailed> {
     guard let application,
           let port = await controller?.getPort(request),
-          let participant = try? application.findParticipant(port: port.0)
+          let participant = try? await application.findParticipant(port: port.0)
     else {
       throw HTTPUnhandledError()
     }
@@ -580,7 +583,7 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
   func getTalkerFailedByStreamID(_ request: HTTPRequest) async throws -> TalkerFailed {
     guard let application,
           let (port, streamID) = await application._getPortAndStream(request),
-          let participant = try? application.findParticipant(port: port)
+          let participant = try? await application.findParticipant(port: port)
     else {
       throw HTTPUnhandledError()
     }
@@ -816,7 +819,7 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
   func getStreamListenerByStreamID(_ request: HTTPRequest) async throws -> StreamListener {
     guard let application,
           let (streamID, port) = await application._getStreamAndPort(request),
-          let participant = try? application.findParticipant(port: port)
+          let participant = try? await application.findParticipant(port: port)
     else {
       throw HTTPUnhandledError()
     }
@@ -830,9 +833,9 @@ struct MSRPHandler<P: AVBPort>: Sendable, RestApiApplicationHandler {
 }
 
 fileprivate extension MSRPApplication {
-  func _getTransmitRate(for participant: Participant<MSRPApplication>) async throws -> Int {
+  func _getTransmitRate(for participant: Participant<MSRPApplication>) throws -> Int {
     let portState = try withPortState(port: participant.port) { $0 }
-    let bandwidthUsed = try await _calculateBandwidthUsed(
+    let bandwidthUsed = try _calculateBandwidthUsed(
       participant: participant,
       portState: portState
     )
@@ -878,15 +881,15 @@ fileprivate extension MSRPApplication {
 }
 
 fileprivate extension Participant where A.P: AVBPort {
-  func _getListeners() -> [MSRPHandler<A.P>.Listener] {
-    findAllAttributes(
+  func _getListeners() async -> [MSRPHandler<A.P>.Listener] {
+    await findAllAttributes(
       attributeType: MSRPAttributeType.listener.rawValue,
       matching: .matchAny
     ).map { MSRPHandler<A.P>.Listener(attributeValue: $0) }
   }
 
-  func _getListener(streamID: MSRPStreamID) -> MSRPHandler<A.P>.Listener? {
-    findAllAttributes(
+  func _getListener(streamID: MSRPStreamID) async -> MSRPHandler<A.P>.Listener? {
+    await findAllAttributes(
       attributeType: MSRPAttributeType.listener.rawValue,
       matching: .matchIndex(streamID)
     ).map { MSRPHandler<A.P>.Listener(attributeValue: $0) }
@@ -895,15 +898,15 @@ fileprivate extension Participant where A.P: AVBPort {
 }
 
 fileprivate extension Participant where A.P: AVBPort {
-  func _getTalkers() -> [MSRPHandler<A.P>.Talker] {
-    findAllAttributes(
+  func _getTalkers() async -> [MSRPHandler<A.P>.Talker] {
+    await findAllAttributes(
       attributeType: MSRPAttributeType.talkerAdvertise.rawValue,
       matching: .matchAny
     ).map { MSRPHandler<A.P>.Talker(attributeValue: $0) }
   }
 
-  func _getTalker(streamID: MSRPStreamID) -> MSRPHandler<A.P>.Talker? {
-    findAllAttributes(
+  func _getTalker(streamID: MSRPStreamID) async -> MSRPHandler<A.P>.Talker? {
+    await findAllAttributes(
       attributeType: MSRPAttributeType.talkerAdvertise.rawValue,
       matching: .matchIndex(streamID)
     )
@@ -913,15 +916,15 @@ fileprivate extension Participant where A.P: AVBPort {
 }
 
 fileprivate extension Participant where A.P: AVBPort {
-  func _getTalkersFailed() -> [MSRPHandler<A.P>.TalkerFailed] {
-    findAllAttributes(
+  func _getTalkersFailed() async -> [MSRPHandler<A.P>.TalkerFailed] {
+    await findAllAttributes(
       attributeType: MSRPAttributeType.talkerFailed.rawValue,
       matching: .matchAny
     ).map { MSRPHandler<A.P>.TalkerFailed(attributeValue: $0) }
   }
 
-  func _getTalkerFailed(streamID: MSRPStreamID) -> MSRPHandler<A.P>.TalkerFailed? {
-    findAllAttributes(
+  func _getTalkerFailed(streamID: MSRPStreamID) async -> MSRPHandler<A.P>.TalkerFailed? {
+    await findAllAttributes(
       attributeType: MSRPAttributeType.talkerFailed.rawValue,
       matching: .matchIndex(streamID)
     )
@@ -931,16 +934,15 @@ fileprivate extension Participant where A.P: AVBPort {
 }
 
 fileprivate extension Participant where A.P: AVBPort {
-  func _getStreamListener(streamID: MSRPStreamID) -> MSRPHandler<A.P>.Stream.Listener? {
-    findAllAttributes(
+  func _getStreamListener(streamID: MSRPStreamID) async -> MSRPHandler<A.P>.Stream.Listener? {
+    await findAllAttributes(
       attributeType: MSRPAttributeType.listener.rawValue,
       matching: .matchIndex(streamID)
-    )
-    .filter(\.isRegistered)
-    .map { MSRPHandler<A.P>.Stream.Listener(
-      participant: self as! Participant<MSRPApplication<A.P>>,
-      attributeValue: $0
-    ) }.first
+    ).filter(\.isRegistered)
+      .asyncMap { await MSRPHandler<A.P>.Stream.Listener(
+        participant: self as! Participant<MSRPApplication<A.P>>,
+        attributeValue: $0
+      ) }.first
   }
 }
 
diff --git a/Sources/MRP/Applications/MVRP/MVRPApplication.swift b/Sources/MRP/Applications/MVRP/MVRPApplication.swift
index 78cb74c5..e2dd9e0b 100644
--- a/Sources/MRP/Applications/MVRP/MVRPApplication.swift
+++ b/Sources/MRP/Applications/MVRP/MVRPApplication.swift
@@ -32,34 +32,32 @@ protocol MVRPAwareBridge<P>: Bridge where P: Port {
   func deregister(vlan: VLAN, from port: P) async throws
 }
 
-public final class MVRPApplication<P: Port>: BaseApplication, BaseApplicationEventObserver,
-  BaseApplicationContextObserver, CustomStringConvertible,
-  Sendable where P == P
+public actor MVRPApplication<P: Port>: BaseApplication, BaseApplicationEventObserver, Sendable,
+  BaseApplicationContextObserver, CustomStringConvertible where P == P
 {
   // for now, we only operate in the Base Spanning Tree Context
-  public var nonBaseContextsSupported: Bool { false }
+  public nonisolated var nonBaseContextsSupported: Bool { false }
 
-  public var validAttributeTypes: ClosedRange<AttributeType> {
+  public nonisolated var validAttributeTypes: ClosedRange<AttributeType> {
     MVRPAttributeType.validAttributeTypes
   }
 
   // 10.12.1.3 MVRP application address
-  public var groupAddress: EUI48 { CustomerBridgeMRPGroupAddress }
+  public nonisolated var groupAddress: EUI48 { CustomerBridgeMRPGroupAddress }
 
   // 10.12.1.4 MVRP application EtherType
-  public var etherType: UInt16 { MVRPEtherType }
+  public nonisolated var etherType: UInt16 { MVRPEtherType }
 
   // 10.12.1.5 MVRP ProtocolVersion
-  public var protocolVersion: ProtocolVersion { 0 }
+  public nonisolated var protocolVersion: ProtocolVersion { 0 }
 
-  public var hasAttributeListLength: Bool { false }
+  public nonisolated var hasAttributeListLength: Bool { false }
 
   let _controller: Weak<MRPController<P>>
 
-  public var controller: MRPController<P>? { _controller.object }
+  public nonisolated var controller: MRPController<P>? { _controller.object }
 
-  let _participants =
-    Mutex<[MAPContextIdentifier: Set<Participant<MVRPApplication<P>>>]>([:])
+  var _participants: [MAPContextIdentifier: Set<Participant<MVRPApplication<P>>>] = [:]
   let _logger: Logger
   let _vlanExclusions: Set<VLAN>
 
@@ -70,14 +68,13 @@ public final class MVRPApplication<P: Port>: BaseApplication, BaseApplicationEve
     try await controller.register(application: self)
   }
 
-  public var description: String {
-    let participants: String = _participants.withLock { String(describing: $0) }
-    return "MVRPApplication(controller: \(controller!), vlanExclusions: \(_vlanExclusions), participants: \(participants))"
+  public nonisolated var description: String {
+    "MVRPApplication(controller: \(controller!))"
   }
 
-  public var name: String { "MVRP" }
+  public nonisolated var name: String { "MVRP" }
 
-  public func deserialize(
+  public nonisolated func deserialize(
     attributeOfType attributeType: AttributeType,
     from input: inout ParserSpan
   ) throws -> any Value {
@@ -89,7 +86,7 @@ public final class MVRPApplication<P: Port>: BaseApplication, BaseApplicationEve
     }
   }
 
-  public func makeNullValue(for attributeType: AttributeType) throws -> any Value {
+  public nonisolated func makeNullValue(for attributeType: AttributeType) throws -> any Value {
     guard let attributeType = MVRPAttributeType(rawValue: attributeType)
     else { throw MRPError.unknownAttributeType }
     switch attributeType {
@@ -98,11 +95,11 @@ public final class MVRPApplication<P: Port>: BaseApplication, BaseApplicationEve
     }
   }
 
-  public func hasAttributeSubtype(for: AttributeType) -> Bool {
+  public nonisolated func hasAttributeSubtype(for: AttributeType) -> Bool {
     false
   }
 
-  public func administrativeControl(for attributeType: AttributeType) throws
+  public nonisolated func administrativeControl(for attributeType: AttributeType) throws
     -> AdministrativeControl
   {
     .normalParticipant
@@ -114,8 +111,8 @@ public final class MVRPApplication<P: Port>: BaseApplication, BaseApplicationEve
   // Vector Attribute Type (11.2.3.1.6) and the attribute_value parameter
   // carries the value of the VID parameter carried in the
   // ES_REGISTER_VLAN_MEMBER primitive.
-  public func register(vlanMember: VLAN) async throws {
-    try await join(
+  public func register(vlanMember: VLAN) throws {
+    try join(
       attributeType: MVRPAttributeType.vid.rawValue,
       attributeValue: vlanMember,
       isNew: false,
@@ -129,8 +126,8 @@ public final class MVRPApplication<P: Port>: BaseApplication, BaseApplicationEve
   // Vector Attribute Type (11.2.3.1.6) and the attribute_value parameter
   // carries the value of the VID parameter carried in the
   // ES_DEREGISTER_VLAN_MEMBER primitive.
-  public func deregister(vlanMember: VLAN) async throws {
-    try await leave(
+  public func deregister(vlanMember: VLAN) throws {
+    try leave(
       attributeType: MVRPAttributeType.vid.rawValue,
       attributeValue: vlanMember,
       for: MAPBaseSpanningTreeContext
@@ -140,8 +137,8 @@ public final class MVRPApplication<P: Port>: BaseApplication, BaseApplicationEve
   public func periodic(for contextIdentifier: MAPContextIdentifier?) async throws {
     // 5.4.4 the Periodic Transmission state machine (10.7.10) is specifically
     // excluded from MSRP
-    try await apply(for: contextIdentifier) { participant in
-      try await participant.periodic()
+    try apply(for: contextIdentifier) { participant in
+      try participant.periodic()
     }
   }
 }
@@ -221,7 +218,7 @@ extension MVRPApplication {
   ) async throws {
     guard let bridge = controller?.bridge as? any MVRPAwareBridge<P>,
           !bridge.hasLocalMVRPApplicant else { return }
-    try await join(
+    try join(
       attributeType: MVRPAttributeType.vid.rawValue,
       attributeValue: VLAN(contextIdentifier: contextIdentifier),
       isNew: true,
@@ -232,21 +229,19 @@ extension MVRPApplication {
   func onContextUpdated(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {}
+  ) async throws {}
 
   func onContextRemoved(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {
+  ) async throws {
     guard let bridge = controller?.bridge as? any MVRPAwareBridge<P>,
           !bridge.hasLocalMVRPApplicant else { return }
-    Task {
-      try await leave(
-        attributeType: MVRPAttributeType.vid.rawValue,
-        attributeValue: VLAN(contextIdentifier: contextIdentifier),
-        for: MAPBaseSpanningTreeContext
-      )
-    }
+    try leave(
+      attributeType: MVRPAttributeType.vid.rawValue,
+      attributeValue: VLAN(contextIdentifier: contextIdentifier),
+      for: MAPBaseSpanningTreeContext
+    )
   }
 }
 
diff --git a/Sources/MRP/Base/MRPController.swift b/Sources/MRP/Base/MRPController.swift
index 595b2ae2..60b5fb06 100644
--- a/Sources/MRP/Base/MRPController.swift
+++ b/Sources/MRP/Base/MRPController.swift
@@ -116,7 +116,7 @@ public actor MRPController<P: Port>: Service, CustomStringConvertible, Sendable
     #endif
     try? await bridge.shutdown(controller: self)
     for port in ports {
-      try? _didRemove(port: port)
+      try? await _didRemove(port: port)
     }
   }
 
@@ -206,13 +206,13 @@ public actor MRPController<P: Port>: Service, CustomStringConvertible, Sendable
       )
 
     for contextIdentifier in removedContextIdentifiers {
-      try _didRemove(contextIdentifier: contextIdentifier, with: [port])
+      try await _didRemove(contextIdentifier: contextIdentifier, with: [port])
     }
 
     for contextIdentifier in updatedContextIdentifiers
       .union(isNewPort ? [] : [MAPBaseSpanningTreeContext])
     {
-      try _didUpdate(contextIdentifier: contextIdentifier, with: [port])
+      try await _didUpdate(contextIdentifier: contextIdentifier, with: [port])
     }
 
     for contextIdentifier in addedContextIdentifiers
@@ -222,7 +222,7 @@ public actor MRPController<P: Port>: Service, CustomStringConvertible, Sendable
     }
   }
 
-  private func _applyContextIdentifierChanges(beforeRemoving port: P) throws {
+  private func _applyContextIdentifierChanges(beforeRemoving port: P) async throws {
     let removedContextIdentifiers: Set<MAPContextIdentifier>
 
     guard let existingPort = ports.first(where: { $0.id == port.id }) else { return }
@@ -234,7 +234,7 @@ public actor MRPController<P: Port>: Service, CustomStringConvertible, Sendable
       )
 
     for contextIdentifier in [MAPBaseSpanningTreeContext] + removedContextIdentifiers {
-      try _didRemove(contextIdentifier: contextIdentifier, with: [port])
+      try await _didRemove(contextIdentifier: contextIdentifier, with: [port])
     }
   }
 
@@ -247,10 +247,10 @@ public actor MRPController<P: Port>: Service, CustomStringConvertible, Sendable
     _ports[port.id] = port
   }
 
-  private func _didRemove(port: P) throws {
+  private func _didRemove(port: P) async throws {
     logger.debug("removed port \(port.id): \(port)")
 
-    try _applyContextIdentifierChanges(beforeRemoving: port)
+    try await _applyContextIdentifierChanges(beforeRemoving: port)
     _ports[port.id] = nil
 
     if timerConfiguration.periodicTime != .zero { _stopPeriodicTimer() }
@@ -271,7 +271,7 @@ public actor MRPController<P: Port>: Service, CustomStringConvertible, Sendable
         case let .added(port):
           try await ports.contains(port) ? _didUpdate(port: port) : _didAdd(port: port)
         case let .removed(port):
-          try _didRemove(port: port)
+          try await _didRemove(port: port)
         case let .changed(port):
           try await _didUpdate(port: port)
         }
@@ -394,18 +394,18 @@ public actor MRPController<P: Port>: Service, CustomStringConvertible, Sendable
   private func _didUpdate(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {
+  ) async throws {
     for application in _applications.values {
-      try application.didUpdate(contextIdentifier: contextIdentifier, with: context)
+      try await application.didUpdate(contextIdentifier: contextIdentifier, with: context)
     }
   }
 
   private func _didRemove(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {
+  ) async throws {
     for application in _applications.values {
-      try application.didRemove(contextIdentifier: contextIdentifier, with: context)
+      try await application.didRemove(contextIdentifier: contextIdentifier, with: context)
     }
   }
 
diff --git a/Sources/MRP/Base/Utility.swift b/Sources/MRP/Base/Utility.swift
index 64f58780..7c7b67f4 100644
--- a/Sources/MRP/Base/Utility.swift
+++ b/Sources/MRP/Base/Utility.swift
@@ -30,14 +30,6 @@ extension Weak: Equatable where T: Equatable {
   }
 }
 
-// https://stackoverflow.com/questions/25329186/safe-bounds-checked-array-lookup-in-swift-through-optional-bindings
-extension Collection {
-  /// Returns the element at the specified index if it is within bounds, otherwise nil.
-  subscript(safe index: Index) -> Element? {
-    indices.contains(index) ? self[index] : nil
-  }
-}
-
 extension Array {
   /// Creates an array from a collection, padding to a multiple of the specified value.
   init(_ collection: some Collection<Element>, multiple: Int, with element: Element) {
@@ -61,18 +53,15 @@ public extension Sequence {
     return values
   }
 
-  func asyncCompactMap<T>(
-    _ transform: (Element) async throws -> T?
-  ) async rethrows -> [T] {
-    var values = [T]()
-
+  func asyncReduce<Result>(
+    into initialResult: Result,
+    _ updateAccumulatingResult: (inout Result, Element) async throws -> ()
+  ) async rethrows -> Result {
+    var result = initialResult
     for element in self {
-      if let transformed = try await transform(element) {
-        values.append(transformed)
-      }
+      try await updateAccumulatingResult(&result, element)
     }
-
-    return values
+    return result
   }
 }
 
diff --git a/Sources/MRP/Model/Application.swift b/Sources/MRP/Model/Application.swift
index e1866896..b674cb55 100644
--- a/Sources/MRP/Model/Application.swift
+++ b/Sources/MRP/Model/Application.swift
@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2024 PADL Software Pty Ltd
+// Copyright (c) 2024-2026 PADL Software Pty Ltd
 //
 // Licensed under the Apache License, Version 2.0 (the License);
 // you may not use this file except in compliance with the License.
@@ -26,27 +26,27 @@ public enum AdministrativeControl {
 
 public typealias AttributeSubtype = UInt8
 
-public protocol Application<P>: AnyObject, Equatable, Hashable, Sendable {
+public protocol Application<P>: Actor, Equatable, Hashable, Sendable {
   associatedtype P: Port
 
   typealias ApplyFunction<T> = (Participant<Self>) throws -> T
   typealias AsyncApplyFunction<T> = (Participant<Self>) async throws -> T
 
-  var validAttributeTypes: ClosedRange<AttributeType> { get }
-  var groupAddress: EUI48 { get }
-  var etherType: UInt16 { get }
-  var protocolVersion: ProtocolVersion { get }
-  var hasAttributeListLength: Bool { get }
-  var name: String { get }
+  nonisolated var validAttributeTypes: ClosedRange<AttributeType> { get }
+  nonisolated var groupAddress: EUI48 { get }
+  nonisolated var etherType: UInt16 { get }
+  nonisolated var protocolVersion: ProtocolVersion { get }
+  nonisolated var hasAttributeListLength: Bool { get }
+  nonisolated var name: String { get }
 
-  var controller: MRPController<P>? { get }
+  nonisolated var controller: MRPController<P>? { get }
 
   // notifications from controller when a port is added, didUpdated or removed
   // if contextIdentifier is MAPBaseSpanningTreeContext, the ports are physical
   // ports on the bridge; otherwise, they are virtual ports managed by MVRP.
   func didAdd(contextIdentifier: MAPContextIdentifier, with context: MAPContext<P>) async throws
-  func didUpdate(contextIdentifier: MAPContextIdentifier, with context: MAPContext<P>) throws
-  func didRemove(contextIdentifier: MAPContextIdentifier, with context: MAPContext<P>) throws
+  func didUpdate(contextIdentifier: MAPContextIdentifier, with context: MAPContext<P>) async throws
+  func didRemove(contextIdentifier: MAPContextIdentifier, with context: MAPContext<P>) async throws
 
   // apply for all participants. if contextIdentifier is nil, then all participants are called
   // regardless of contextIdentifier.
@@ -62,12 +62,12 @@ public protocol Application<P>: AnyObject, Equatable, Hashable, Sendable {
     _ block: AsyncApplyFunction<T>
   ) async rethrows -> [T]
 
-  func hasAttributeSubtype(for: AttributeType) -> Bool
-  func administrativeControl(for: AttributeType) throws -> AdministrativeControl
-  var nonBaseContextsSupported: Bool { get }
+  nonisolated func hasAttributeSubtype(for: AttributeType) -> Bool
+  nonisolated func administrativeControl(for: AttributeType) throws -> AdministrativeControl
+  nonisolated var nonBaseContextsSupported: Bool { get }
 
-  func makeNullValue(for attributeType: AttributeType) throws -> any Value
-  func deserialize(
+  nonisolated func makeNullValue(for attributeType: AttributeType) throws -> any Value
+  nonisolated func deserialize(
     attributeOfType attributeType: AttributeType,
     from input: inout ParserSpan
   ) throws -> any Value
@@ -95,11 +95,11 @@ public protocol Application<P>: AnyObject, Equatable, Hashable, Sendable {
 }
 
 public extension Application {
-  func hash(into hasher: inout Hasher) {
+  nonisolated func hash(into hasher: inout Hasher) {
     etherType.hash(into: &hasher)
   }
 
-  static func == (lhs: Self, rhs: Self) -> Bool {
+  nonisolated static func == (lhs: Self, rhs: Self) -> Bool {
     lhs.etherType == rhs.etherType
   }
 }
@@ -118,16 +118,6 @@ extension Application {
     }
   }
 
-  private func apply<T>(
-    for contextIdentifier: MAPContextIdentifier,
-    with arg: T,
-    _ block: AsyncParticipantSpecificApplyFunction<T>
-  ) async throws {
-    try await apply(for: contextIdentifier) { participant in
-      try await block(participant)(arg)
-    }
-  }
-
   func findParticipants(for contextIdentifier: MAPContextIdentifier? = nil)
     -> [Participant<Self>]
   {
@@ -152,9 +142,9 @@ extension Application {
     attributeValue: some Value,
     isNew: Bool,
     for contextIdentifier: MAPContextIdentifier
-  ) async throws {
-    try await apply(for: contextIdentifier) { participant in
-      try await participant.join(
+  ) throws {
+    try apply(for: contextIdentifier) { participant in
+      try participant.join(
         attributeType: attributeType,
         attributeSubtype: attributeSubtype,
         attributeValue: attributeValue,
@@ -169,9 +159,9 @@ extension Application {
     attributeSubtype: AttributeSubtype? = nil,
     attributeValue: some Value,
     for contextIdentifier: MAPContextIdentifier
-  ) async throws {
-    try await apply(for: contextIdentifier) { participant in
-      try await participant.leave(
+  ) throws {
+    try apply(for: contextIdentifier) { participant in
+      try participant.leave(
         attributeType: attributeType,
         attributeSubtype: attributeSubtype,
         attributeValue: attributeValue,
@@ -180,11 +170,11 @@ extension Application {
     }
   }
 
-  func rx(packet: IEEE802Packet, from port: P) async throws {
+  func rx(packet: IEEE802Packet, from port: P) throws {
     let pdu = try packet.payload.withParserSpan { input in
       try MRPDU(parsing: &input, application: self)
     }
-    try await rx(
+    try rx(
       pdu: pdu,
       for: MAPContextIdentifier(packet: packet),
       from: port,
@@ -197,16 +187,16 @@ extension Application {
     for contextIdentifier: MAPContextIdentifier,
     from port: P,
     sourceMacAddress: EUI48
-  ) async throws {
+  ) throws {
     let participant = try findParticipant(for: contextIdentifier, port: port)
-    try await participant.rx(pdu: pdu, sourceMacAddress: sourceMacAddress)
+    try participant.rx(pdu: pdu, sourceMacAddress: sourceMacAddress)
   }
 
-  func flush(for contextIdentifier: MAPContextIdentifier) async throws {
-    try await apply(for: contextIdentifier) { try await $0.flush() }
+  func flush(for contextIdentifier: MAPContextIdentifier) throws {
+    try apply(for: contextIdentifier) { try $0.flush() }
   }
 
-  func redeclare(for contextIdentifier: MAPContextIdentifier) async throws {
-    try await apply(for: contextIdentifier) { try await $0.redeclare() }
+  func redeclare(for contextIdentifier: MAPContextIdentifier) throws {
+    try apply(for: contextIdentifier) { try $0.redeclare() }
   }
 }
diff --git a/Sources/MRP/Model/BaseApplication.swift b/Sources/MRP/Model/BaseApplication.swift
index c4ffb290..60c17a83 100644
--- a/Sources/MRP/Model/BaseApplication.swift
+++ b/Sources/MRP/Model/BaseApplication.swift
@@ -21,7 +21,7 @@ protocol BaseApplication: Application where P == P {
   typealias MAPParticipantDictionary = [MAPContextIdentifier: Set<Participant<Self>>]
 
   var _controller: Weak<MRPController<P>> { get }
-  var _participants: Mutex<MAPParticipantDictionary> { get }
+  var _participants: MAPParticipantDictionary { get set }
 }
 
 protocol BaseApplicationContextObserver<P>: BaseApplication {
@@ -29,8 +29,14 @@ protocol BaseApplicationContextObserver<P>: BaseApplication {
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
   ) async throws
-  func onContextUpdated(contextIdentifier: MAPContextIdentifier, with context: MAPContext<P>) throws
-  func onContextRemoved(contextIdentifier: MAPContextIdentifier, with context: MAPContext<P>) throws
+  func onContextUpdated(
+    contextIdentifier: MAPContextIdentifier,
+    with context: MAPContext<P>
+  ) async throws
+  func onContextRemoved(
+    contextIdentifier: MAPContextIdentifier,
+    with context: MAPContext<P>
+  ) async throws
 }
 
 protocol BaseApplicationEventObserver<P>: BaseApplication {
@@ -61,12 +67,10 @@ extension BaseApplication {
       nonBaseContextsSupported || participant
         .contextIdentifier == MAPBaseSpanningTreeContext
     )
-    _participants.withLock {
-      if let index = $0.index(forKey: participant.contextIdentifier) {
-        $0.values[index].insert(participant)
-      } else {
-        $0[participant.contextIdentifier] = Set([participant])
-      }
+    if let index = _participants.index(forKey: participant.contextIdentifier) {
+      _participants.values[index].insert(participant)
+    } else {
+      _participants[participant.contextIdentifier] = Set([participant])
     }
   }
 
@@ -77,9 +81,7 @@ extension BaseApplication {
       nonBaseContextsSupported || participant
         .contextIdentifier == MAPBaseSpanningTreeContext
     )
-    _ = _participants.withLock {
-      $0[participant.contextIdentifier]?.remove(participant)
-    }
+    _participants[participant.contextIdentifier]?.remove(participant)
   }
 
   @discardableResult
@@ -87,13 +89,10 @@ extension BaseApplication {
     for contextIdentifier: MAPContextIdentifier? = nil,
     _ block: AsyncApplyFunction<T>
   ) async rethrows -> [T] {
-    var participants: Set<Participant<Self>>?
-    _participants.withLock {
-      if let contextIdentifier {
-        participants = $0[contextIdentifier]
-      } else {
-        participants = Set($0.flatMap { Array($1) })
-      }
+    let participants: Set<Participant<Self>>? = if let contextIdentifier {
+      _participants[contextIdentifier]
+    } else {
+      Set(_participants.flatMap { Array($1) })
     }
     var ret = [T]()
     if let participants {
@@ -109,13 +108,10 @@ extension BaseApplication {
     for contextIdentifier: MAPContextIdentifier? = nil,
     _ block: ApplyFunction<T>
   ) rethrows -> [T] {
-    var participants: Set<Participant<Self>>?
-    _participants.withLock {
-      if let contextIdentifier {
-        participants = $0[contextIdentifier]
-      } else {
-        participants = Set($0.flatMap { Array($1) })
-      }
+    let participants: Set<Participant<Self>>? = if let contextIdentifier {
+      _participants[contextIdentifier]
+    } else {
+      Set(_participants.flatMap { Array($1) })
     }
     var ret = [T]()
     if let participants {
@@ -143,7 +139,7 @@ extension BaseApplication {
           throw MRPError.portAlreadyExists
         }
         guard let controller else { throw MRPError.internalError }
-        let participant = await Participant<Self>(
+        let participant = Participant<Self>(
           controller: controller,
           application: self,
           port: port,
@@ -164,32 +160,32 @@ extension BaseApplication {
   public func didUpdate(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {
+  ) async throws {
     if _isParticipantValid(contextIdentifier: contextIdentifier) {
       for port in context {
         let participant = try findParticipant(
           for: contextIdentifier,
           port: port
         )
-        Task { try await participant.redeclare() }
+        try participant.redeclare()
       }
     }
     // also call this regardless of the value of nonBaseContextsSupported, so that
     // MVRP can be advised of VLAN changes on a port
     if let observer = self as? any BaseApplicationContextObserver<P> {
-      try observer.onContextUpdated(contextIdentifier: contextIdentifier, with: context)
+      try await observer.onContextUpdated(contextIdentifier: contextIdentifier, with: context)
     }
   }
 
   public func didRemove(
     contextIdentifier: MAPContextIdentifier,
     with context: MAPContext<P>
-  ) throws {
+  ) async throws {
     // call observer _before_ removing participants so it can do any other cleanup
     // also call this regardless of the value of nonBaseContextsSupported, so that
     // MVRP can be advised of VLAN changes on a port
     if let observer = self as? any BaseApplicationContextObserver<P> {
-      try observer.onContextRemoved(contextIdentifier: contextIdentifier, with: context)
+      try await observer.onContextRemoved(contextIdentifier: contextIdentifier, with: context)
     }
     if _isParticipantValid(contextIdentifier: contextIdentifier) {
       for port in context {
@@ -197,7 +193,7 @@ extension BaseApplication {
           for: contextIdentifier,
           port: port
         )
-        Task { try await participant.flush() }
+        try participant.flush()
         try remove(participant: participant)
       }
     }
@@ -236,11 +232,11 @@ extension BaseApplication {
     attributeValue: some Value,
     isNew: Bool,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     guard shouldPropagate(eventSource: eventSource) else { return }
-    try await apply(for: contextIdentifier) { participant in
+    try apply(for: contextIdentifier) { participant in
       guard participant.port != port else { return }
-      try await participant.join(
+      try participant.join(
         attributeType: attributeType,
         attributeSubtype: attributeSubtype,
         attributeValue: attributeValue,
@@ -275,7 +271,7 @@ extension BaseApplication {
     } catch MRPError.doNotPropagateAttribute {
       return
     }
-    try await _propagateJoinIndicated(
+    try _propagateJoinIndicated(
       contextIdentifier: contextIdentifier,
       port: port,
       attributeType: attributeType,
@@ -293,11 +289,11 @@ extension BaseApplication {
     attributeSubtype: AttributeSubtype?,
     attributeValue: some Value,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     guard shouldPropagate(eventSource: eventSource) else { return }
-    try await apply(for: contextIdentifier) { participant in
+    try apply(for: contextIdentifier) { participant in
       guard participant.port != port else { return }
-      try await participant.leave(
+      try participant.leave(
         attributeType: attributeType,
         attributeSubtype: attributeSubtype,
         attributeValue: attributeValue,
@@ -329,7 +325,7 @@ extension BaseApplication {
     } catch MRPError.doNotPropagateAttribute {
       return
     }
-    try await _propagateLeaveIndicated(
+    try _propagateLeaveIndicated(
       contextIdentifier: contextIdentifier,
       port: port,
       attributeType: attributeType,
diff --git a/Sources/MRP/Model/Participant.swift b/Sources/MRP/Model/Participant.swift
index 8c51b8eb..1297b5db 100644
--- a/Sources/MRP/Model/Participant.swift
+++ b/Sources/MRP/Model/Participant.swift
@@ -100,7 +100,9 @@ private enum EnqueuedEvent<A: Application>: Equatable, CustomStringConvertible {
   }
 }
 
-public final actor Participant<A: Application>: Equatable, Hashable, CustomStringConvertible {
+public final class Participant<A: Application>: Equatable, Hashable, CustomStringConvertible,
+  @unchecked Sendable
+{
   public static func == (lhs: Participant<A>, rhs: Participant<A>) -> Bool {
     lhs.application == rhs.application && lhs.port == rhs.port && lhs.contextIdentifier == rhs
       .contextIdentifier
@@ -116,10 +118,11 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
 
   private var _attributes = [AttributeType: Set<_AttributeValue<A>>]()
   private var _enqueuedEvents = EnqueuedEvents()
-  private var _leaveAll: LeaveAll!
-  private var _jointimer: Timer!
+  private nonisolated(unsafe) var _leaveAll: LeaveAll!
+  private nonisolated(unsafe) var _jointimer: Timer!
   private var _rxInProgress = false
   private var _transmissionOpportunityTimestamps: [ContinuousClock.Instant] = []
+
   private nonisolated let _controller: Weak<MRPController<A.P>>
   private nonisolated let _application: Weak<A>
 
@@ -137,7 +140,7 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     port: A.P,
     contextIdentifier: MAPContextIdentifier,
     type: ParticipantType? = nil
-  ) async {
+  ) {
     _controller = Weak(controller)
     _application = Weak(application)
     self.contextIdentifier = contextIdentifier
@@ -157,6 +160,10 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     _logger.trace("\(self): initialized participant type \(_type)")
   }
 
+  private func _assertIsolatedToApplication() {
+    application?.assertIsolated("MRP Participant must be called from Application isolation")
+  }
+
   public nonisolated var description: String {
     "\(application!.name)@\(port.name)"
   }
@@ -167,7 +174,10 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     // instance of this timer is required on a per-Port, per-MRP Participant
     // basis. The value of JoinTime used to initialize this timer is determined
     // in accordance with 10.7.11.
-    _jointimer = Timer(label: "jointimer", onExpiry: _onTxOpportunity)
+    _jointimer = Timer(label: "jointimer") { @Sendable [self] in
+      guard let application else { return }
+      try await _onTxOpportunity(isolation: application)
+    }
 
     // The Leave All Period Timer, leavealltimer, controls the frequency with
     // which the LeaveAll state machine generates LeaveAll PDUs. The timer is
@@ -176,10 +186,12 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     // All Period Timer is set to a random value, T, in the range LeaveAllTime
     // < T < 1.5 × LeaveAllTime when it is started. LeaveAllTime is defined in
     // Table 10-7.
-    _leaveAll = LeaveAll(
-      interval: controller!.timerConfiguration.leaveAllTime,
-      onLeaveAllTimerExpired: _onLeaveAllTimerExpired
-    )
+    _leaveAll = LeaveAll(interval: controller!.timerConfiguration
+      .leaveAllTime)
+    { @Sendable [self] in
+      guard let application else { return }
+      try await _onLeaveAllTimerExpired(isolation: application)
+    }
   }
 
   deinit {
@@ -187,20 +199,21 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     _leaveAll?.stopLeaveAllTimer()
   }
 
-  @Sendable
-  private func _onLeaveAllTimerExpired() async throws {
-    try await _handleLeaveAll(protocolEvent: .leavealltimer, eventSource: .leaveAllTimer)
+  private func _onLeaveAllTimerExpired(isolation: isolated A) throws {
+    try _handleLeaveAll(protocolEvent: .leavealltimer, eventSource: .leaveAllTimer)
   }
 
   private func _apply(
     attributeType: AttributeType? = nil,
     matching filter: AttributeValueFilter = .matchAny,
-    _ block: AsyncParticipantApplyFunction<A>
-  ) async rethrows {
+    _ block: ParticipantApplyFunction<A>
+  ) rethrows {
+    _assertIsolatedToApplication()
+
     for attribute in _attributes {
       for attributeValue in attribute.value {
         if !attributeValue.matches(attributeType: attributeType, matching: filter) { continue }
-        try await block(attributeValue)
+        try block(attributeValue)
       }
     }
   }
@@ -209,10 +222,10 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     attributeType: AttributeType? = nil,
     protocolEvent event: ProtocolEvent,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     _logger.trace("\(self): apply protocolEvent \(event), eventSource: \(eventSource)")
-    try await _apply(attributeType: attributeType) { attributeValue in
-      try await _handleAttributeValue(
+    try _apply(attributeType: attributeType) { attributeValue in
+      try _handleAttributeValue(
         attributeValue,
         protocolEvent: event,
         eventSource: eventSource
@@ -259,8 +272,9 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     _jointimer.start(interval: interval)
   }
 
-  @Sendable
-  private func _onTxOpportunity() async throws {
+  private func _onTxOpportunity(isolation: isolated A) async throws {
+    _assertIsolatedToApplication()
+
     let eventSource = EventSource.joinTimer
 
     // Suppress TX opportunities while RX is processing to prevent interleaving
@@ -295,11 +309,11 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     switch _leaveAll.state {
     case .Active:
       // encode attributes first with current registrar states, then process LeaveAll
-      try await _apply(protocolEvent: .txLA, eventSource: eventSource)
+      try _apply(protocolEvent: .txLA, eventSource: eventSource)
       // sets LeaveAll to passive and emits sLA action
-      try await _handleLeaveAll(protocolEvent: .tx, eventSource: eventSource)
+      try _handleLeaveAll(protocolEvent: .tx, eventSource: eventSource)
     case .Passive:
-      try await _apply(protocolEvent: .tx, eventSource: eventSource)
+      try _apply(protocolEvent: .tx, eventSource: eventSource)
     }
 
     let didTransmit = try await _tx()
@@ -326,6 +340,8 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     matching filter: AttributeValueFilter,
     createIfMissing: Bool
   ) throws -> _AttributeValue<A> {
+    _assertIsolatedToApplication()
+
     if let attributeValue = _attributes[attributeType]?
       .first(where: { $0.matches(attributeType: attributeType, matching: filter) })
     {
@@ -358,13 +374,17 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     attributeType: AttributeType,
     matching filter: AttributeValueFilter = .matchAny
   ) -> [_AttributeValue<A>] {
-    (_attributes[attributeType] ?? [])
+    _assertIsolatedToApplication()
+
+    return (_attributes[attributeType] ?? [])
       .filter {
         $0.matches(attributeType: attributeType, matching: filter) && $0.isRegistered
       }
   }
 
   fileprivate func _gcAttributeValue(_ attributeValue: _AttributeValue<A>) {
+    _assertIsolatedToApplication()
+
     if let index = _attributes.index(forKey: attributeValue.attributeType) {
       _attributes.values[index].remove(attributeValue)
       if _attributes.values[index].isEmpty {
@@ -377,8 +397,8 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     _ attributeValue: _AttributeValue<A>,
     protocolEvent: ProtocolEvent,
     eventSource: EventSource
-  ) async throws {
-    try await attributeValue.handle(
+  ) throws {
+    try attributeValue.handle(
       protocolEvent: protocolEvent,
       eventSource: eventSource
     )
@@ -480,6 +500,8 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
   }
 
   private func _txEnqueue(_ event: EnqueuedEvent<A>, eventSource: EventSource) {
+    _assertIsolatedToApplication()
+
     if let index = _enqueuedEvents.index(forKey: event.attributeType) {
       if let eventIndex = _enqueuedEvents.values[index]
         .firstIndex(where: { $0 == event })
@@ -518,7 +540,7 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
   private func _handleLeaveAll(
     protocolEvent event: ProtocolEvent,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     let (action, txOpportunity) = _leaveAll.action(for: event) // may update state
 
     if txOpportunity {
@@ -536,7 +558,7 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
       // the rLA! event is responsible for starting the leave timer on
       // registered attributes (Table 10-4), as well as requesting the
       // applicant to redeclare attributes (Table 10-3).
-      try await _apply(protocolEvent: .rLA, eventSource: eventSource)
+      try _apply(protocolEvent: .rLA, eventSource: eventSource)
       try _txEnqueueLeaveAllEvents(eventSource: eventSource)
     default:
       break
@@ -544,7 +566,10 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
   }
 
   private func _txDequeue() throws -> MRPDU? {
+    _assertIsolatedToApplication()
+
     guard let application else { throw MRPError.internalError }
+
     let enqueuedMessages = try _packMessages(with: _enqueuedEvents)
     _enqueuedEvents.removeAll()
 
@@ -558,11 +583,11 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     return pdu
   }
 
-  private func rx(message: Message, eventSource: EventSource, leaveAll: inout Bool) async throws {
+  private func rx(message: Message, eventSource: EventSource, leaveAll: inout Bool) throws {
     for vectorAttribute in message.attributeList {
       // 10.6 Protocol operation: process LeaveAll first.
       if vectorAttribute.leaveAllEvent == .LeaveAll {
-        try await _apply(
+        try _apply(
           attributeType: message.attributeType,
           protocolEvent: .rLA,
           eventSource: eventSource
@@ -595,11 +620,11 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
             .debug(
               "\(self): \(eventSource) declared attribute \(attribute) with new subtype \(attributeSubtype); replacing"
             )
-          try? await attribute.rLvNow(eventSource: eventSource, suppressGC: true)
+          try? attribute.rLvNow(eventSource: eventSource, suppressGC: true)
           attribute.attributeSubtype = attributeSubtype
         }
 
-        try await _handleAttributeValue(
+        try _handleAttributeValue(
           attribute,
           protocolEvent: attributeEvent.protocolEvent,
           eventSource: eventSource
@@ -608,8 +633,11 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
     }
   }
 
-  func rx(pdu: MRPDU, sourceMacAddress: EUI48) async throws {
+  func rx(pdu: MRPDU, sourceMacAddress: EUI48) throws {
+    _assertIsolatedToApplication()
+
     _debugLogPdu(pdu, direction: .rx)
+
     _rxInProgress = true
     defer { _rxInProgress = false }
 
@@ -619,10 +647,10 @@ public final actor Participant<A: Application>: Equatable, Hashable, CustomStrin
       port.macAddress
     ) ? .local : .peer
     for message in pdu.messages {
-      try await rx(message: message, eventSource: eventSource, leaveAll: &leaveAll)
+      try rx(message: message, eventSource: eventSource, leaveAll: &leaveAll)
     }
     if leaveAll {
-      try await _handleLeaveAll(protocolEvent: .rLA, eventSource: eventSource)
+      try _handleLeaveAll(protocolEvent: .rLA, eventSource: eventSource)
     }
   }
 
@@ -731,9 +759,9 @@ public extension Participant {
   // associated with a given Port and spanning tree instance, this event is
   // generated when the Port Role changes from either Root Port or Alternate
   // Port to Designated Port.
-  func flush() async throws {
-    try await _apply(protocolEvent: .Flush, eventSource: .internal)
-    try await _handleLeaveAll(protocolEvent: .Flush, eventSource: .internal)
+  func flush() throws {
+    try _apply(protocolEvent: .Flush, eventSource: .internal)
+    try _handleLeaveAll(protocolEvent: .Flush, eventSource: .internal)
   }
 
   // A Re-declare! event signals to the Applicant and Registrar state machines
@@ -745,8 +773,8 @@ public extension Participant {
   // Registrar state machines associated with a given Port and spanning tree
   // instance, this event is generated when the Port Role changes from
   // Designated Port to either Root Port or Alternate Port.
-  func redeclare() async throws {
-    try await _apply(protocolEvent: .ReDeclare, eventSource: .internal)
+  func redeclare() throws {
+    try _apply(protocolEvent: .ReDeclare, eventSource: .internal)
   }
 
   func join(
@@ -755,7 +783,7 @@ public extension Participant {
     attributeValue: some Value,
     isNew: Bool,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     let attribute = try _findOrCreateAttribute(
       attributeType: attributeType,
       attributeSubtype: attributeSubtype,
@@ -768,11 +796,11 @@ public extension Participant {
         "\(self): \(eventSource) declared attribute \(attribute) with new subtype \(attributeSubtype); replacing"
       )
 
-      try? await attribute.handle(protocolEvent: .Lv, eventSource: eventSource, suppressGC: true)
+      try? attribute.handle(protocolEvent: .Lv, eventSource: eventSource, suppressGC: true)
       attribute.attributeSubtype = attributeSubtype
     }
 
-    try await _handleAttributeValue(
+    try _handleAttributeValue(
       attribute,
       protocolEvent: isNew ? .New : .Join,
       eventSource: eventSource
@@ -784,7 +812,7 @@ public extension Participant {
     attributeSubtype: AttributeSubtype? = nil,
     attributeValue: some Value,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     let attribute = try _findOrCreateAttribute(
       attributeType: attributeType,
       attributeSubtype: attributeSubtype,
@@ -792,7 +820,7 @@ public extension Participant {
       createIfMissing: false
     )
 
-    try await _handleAttributeValue(
+    try _handleAttributeValue(
       attribute,
       protocolEvent: .Lv,
       eventSource: eventSource
@@ -803,7 +831,7 @@ public extension Participant {
     attributeType: AttributeType,
     attributeValue: some Value,
     eventSource: EventSource
-  ) async throws {
+  ) throws {
     let attribute = try _findOrCreateAttribute(
       attributeType: attributeType,
       attributeSubtype: nil,
@@ -811,16 +839,16 @@ public extension Participant {
       createIfMissing: false
     )
 
-    try await _handleAttributeValue(
+    try _handleAttributeValue(
       attribute,
       protocolEvent: .rLvNow,
       eventSource: eventSource
     )
   }
 
-  func periodic() async throws {
+  func periodic() throws {
     _logger.trace("\(self): running periodic")
-    try await _apply(protocolEvent: .periodic, eventSource: .periodicTimer)
+    try _apply(protocolEvent: .periodic, eventSource: .periodicTimer)
     // timer is restarted by the caller
   }
 }
@@ -828,10 +856,13 @@ public extension Participant {
 // MARK: - for use by REST APIs
 
 extension Participant {
-  func findAllAttributes(
-    matching filter: AttributeValueFilter = .matchAny
+  private func findAllAttributesUnchecked(
+    matching filter: AttributeValueFilter,
+    isolation: isolated A
   ) -> [AttributeValue] {
-    _attributes.values.flatMap { $0 }
+    _assertIsolatedToApplication()
+
+    return _attributes.values.flatMap { $0 }
       .map { AttributeValue(
         attributeType: $0.attributeType,
         attributeSubtype: $0.attributeSubtype,
@@ -842,10 +873,20 @@ extension Participant {
   }
 
   func findAllAttributes(
-    attributeType: AttributeType,
     matching filter: AttributeValueFilter = .matchAny
+  ) async -> [AttributeValue] {
+    guard let application else { return [] }
+    return await findAllAttributesUnchecked(matching: filter, isolation: application)
+  }
+
+  func findAllAttributesUnchecked(
+    attributeType: AttributeType,
+    matching filter: AttributeValueFilter,
+    isolation: isolated A
   ) -> [AttributeValue] {
-    (_attributes[attributeType] ?? [])
+    _assertIsolatedToApplication()
+
+    return (_attributes[attributeType] ?? [])
       .filter { $0.matches(attributeType: attributeType, matching: filter) }
       .map { AttributeValue(
         attributeType: attributeType,
@@ -855,10 +896,19 @@ extension Participant {
         registrarState: $0.registrarState
       ) }
   }
-}
 
-private typealias AsyncParticipantApplyFunction<A: Application> =
-  @Sendable (_AttributeValue<A>) async throws -> ()
+  func findAllAttributes(
+    attributeType: AttributeType,
+    matching filter: AttributeValueFilter = .matchAny
+  ) async -> [AttributeValue] {
+    guard let application else { return [] }
+    return await findAllAttributesUnchecked(
+      attributeType: attributeType,
+      matching: filter,
+      isolation: application
+    )
+  }
+}
 
 private typealias ParticipantApplyFunction<A: Application> =
   @Sendable (_AttributeValue<A>) throws -> ()
@@ -958,10 +1008,12 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
     _attributeSubtype = .init(subtype)
     self.value = AnyValue(value)
     if participant._type != .applicantOnly {
-      registrar = Registrar(
-        leaveTime: participant.controller!.timerConfiguration.leaveTime,
-        onLeaveTimerExpired: _onLeaveTimerExpired
-      )
+      registrar = Registrar(leaveTime: participant.controller!.timerConfiguration
+        .leaveTime)
+      { @Sendable [self] in
+        guard let application = participant.application else { return }
+        try await _onLeaveTimerExpired(isolation: application)
+      }
     }
   }
 
@@ -969,9 +1021,8 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
     registrar?.stopLeaveTimer()
   }
 
-  @Sendable
-  private func _onLeaveTimerExpired() async throws {
-    try await handle(
+  private func _onLeaveTimerExpired(isolation: isolated A) throws {
+    try handle(
       protocolEvent: .leavetimer,
       eventSource: .leaveTimer
     )
@@ -1011,7 +1062,7 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
   private func _getEventContext(
     for event: ProtocolEvent,
     eventSource: EventSource,
-    isolation participant: isolated P
+    participant: P
   ) throws -> EventContext<A> {
     try EventContext(
       participant: participant,
@@ -1030,13 +1081,13 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
     protocolEvent event: ProtocolEvent,
     eventSource: EventSource,
     suppressGC: Bool = false
-  ) async throws {
+  ) throws {
     guard let participant else { throw MRPError.internalError }
-    try await _handle(
+    try _handle(
       protocolEvent: event,
       eventSource: eventSource,
       suppressGC: suppressGC,
-      isolation: participant
+      participant: participant
     )
   }
 
@@ -1044,12 +1095,16 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
     protocolEvent event: ProtocolEvent,
     eventSource: EventSource,
     suppressGC: Bool = false,
-    isolation participant: isolated P
-  ) async throws {
-    let context = try _getEventContext(for: event, eventSource: eventSource, isolation: participant)
+    participant: P
+  ) throws {
+    let context = try _getEventContext(
+      for: event,
+      eventSource: eventSource,
+      participant: participant
+    )
 
-    try await _handleRegistrar(context: context, isolation: context.participant)
-    try await _handleApplicant(context: context, isolation: context.participant)
+    try _handleRegistrar(context: context, participant: context.participant)
+    try _handleApplicant(context: context, participant: context.participant)
 
     // remove attribute entirely if it is no longer declared or registered
     if !suppressGC, canGC { participant._gcAttributeValue(self) }
@@ -1057,7 +1112,7 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
 
   private func _handleApplicant(
     context: EventContext<A>,
-    isolation participant: isolated P
+    participant: P
   ) throws {
     participant._logger.trace("\(context.participant): handling applicant \(context)")
 
@@ -1116,8 +1171,8 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
 
   private func _handleRegistrar(
     context: EventContext<A>,
-    isolation participant: isolated P
-  ) async throws {
+    participant: P
+  ) throws {
     context.participant._logger.trace("\(context.participant): handling registrar \(context)")
 
     guard let registrarAction = context.registrar?
@@ -1132,36 +1187,39 @@ private final class _AttributeValue<A: Application>: Sendable, Hashable, Equatab
       )
 
     guard let application = context.participant.application else { throw MRPError.internalError }
-    switch registrarAction {
-    case .New:
-      fallthrough
-    case .Join:
-      try await application.joinIndicated(
-        contextIdentifier: context.participant.contextIdentifier,
-        port: context.participant.port,
-        attributeType: context.attributeType,
-        attributeSubtype: context.attributeSubtype,
-        attributeValue: context.attributeValue,
-        isNew: registrarAction == .New,
-        eventSource: context.eventSource
-      )
-    case .Lv:
-      try await application.leaveIndicated(
-        contextIdentifier: context.participant.contextIdentifier,
-        port: context.participant.port,
-        attributeType: context.attributeType,
-        attributeSubtype: context.attributeSubtype,
-        attributeValue: context.attributeValue,
-        eventSource: context.eventSource
-      )
+
+    Task { @Sendable in
+      switch registrarAction {
+      case .New:
+        fallthrough
+      case .Join:
+        try await application.joinIndicated(
+          contextIdentifier: context.participant.contextIdentifier,
+          port: context.participant.port,
+          attributeType: context.attributeType,
+          attributeSubtype: context.attributeSubtype,
+          attributeValue: context.attributeValue,
+          isNew: registrarAction == .New,
+          eventSource: context.eventSource
+        )
+      case .Lv:
+        try await application.leaveIndicated(
+          contextIdentifier: context.participant.contextIdentifier,
+          port: context.participant.port,
+          attributeType: context.attributeType,
+          attributeSubtype: context.attributeSubtype,
+          attributeValue: context.attributeValue,
+          eventSource: context.eventSource
+        )
+      }
     }
   }
 
   fileprivate func rLvNow(
     eventSource: EventSource,
     suppressGC: Bool = false
-  ) async throws {
-    try await handle(
+  ) throws {
+    try handle(
       protocolEvent: .rLvNow,
       eventSource: eventSource,
       suppressGC: suppressGC
diff --git a/Sources/MRP/RestApi/RestApiHandler.swift b/Sources/MRP/RestApi/RestApiHandler.swift
index 2372d224..cc581233 100644
--- a/Sources/MRP/RestApi/RestApiHandler.swift
+++ b/Sources/MRP/RestApi/RestApiHandler.swift
@@ -159,9 +159,9 @@ extension RestApiApplicationHandler {
   }
 
   /// Validates application and finds participant for port
-  func getParticipant(for port: P) throws -> Participant<A> {
+  func getParticipant(for port: P) async throws -> Participant<A> {
     let application = try requireApplication()
-    return try application.findParticipant(port: port)
+    return try await application.findParticipant(port: port)
   }
 
   /// Validates and extracts application, port, and participant from request
@@ -170,7 +170,7 @@ extension RestApiApplicationHandler {
   {
     let application = try requireApplication()
     let (port, _) = try await getPort(from: request)
-    let participant = try application.findParticipant(port: port)
+    let participant = try await application.findParticipant(port: port)
     return (application, port, participant)
   }
 }