diff --git a/logos_delivery/api/events/kernel_events.nim b/logos_delivery/api/events/kernel_events.nim
new file mode 100644
index 000000000..d8dd46627
--- /dev/null
+++ b/logos_delivery/api/events/kernel_events.nim
@@ -0,0 +1,18 @@
+import brokers/event_broker
+
+import logos_delivery/api/types
+import logos_delivery/waku/waku_core/topics/pubsub_topic
+import logos_delivery/waku/waku_core/message
+
+export event_broker, pubsub_topic, message
+
+EventBroker:
+  # Internal event emitted when a message arrives from the network via any protocol
+  type MessageSeenEvent* = object
+    topic*: PubsubTopic
+    message*: WakuMessage
+
+# Emitted by the health monitor when overall node connectivity changes.
+EventBroker:
+  type EventConnectionStatusChange* = object
+    connectionStatus*: ConnectionStatus
diff --git a/logos_delivery/api/events/messaging_client_events.nim b/logos_delivery/api/events/messaging_client_events.nim
new file mode 100644
index 000000000..b3b7a46f6
--- /dev/null
+++ b/logos_delivery/api/events/messaging_client_events.nim
@@ -0,0 +1,30 @@
+import brokers/event_broker
+
+import logos_delivery/api/types as api_types
+
+export event_broker, api_types
+
+EventBroker:
+  # Event emitted when a message is sent to the network
+  type MessageSentEvent* = object
+    requestId*: RequestId
+    messageHash*: string
+
+EventBroker:
+  # Event emitted when a message send operation fails
+  type MessageErrorEvent* = object
+    requestId*: RequestId
+    messageHash*: string
+    error*: string
+
+EventBroker:
+  # Confirmation that a message has been correctly delivered to some neighbouring nodes.
+  type MessagePropagatedEvent* = object
+    requestId*: RequestId
+    messageHash*: string
+
+EventBroker:
+  # Event emitted when a message is received via Waku
+  type MessageReceivedEvent* = object
+    messageHash*: string
+    message*: WakuMessage
diff --git a/logos_delivery/api/events/reliable_channel_manager_events.nim b/logos_delivery/api/events/reliable_channel_manager_events.nim
new file mode 100644
index 000000000..0f3b4e1ec
--- /dev/null
+++ b/logos_delivery/api/events/reliable_channel_manager_events.nim
@@ -0,0 +1,27 @@
+import brokers/event_broker
+
+import logos_delivery/channels/types as channel_types
+
+export event_broker, channel_types
+
+EventBroker:
+  type ChannelMessageReceivedEvent* = object
+    channelId*: ChannelId
+    senderId*: SdsParticipantID
+    payload*: seq[byte]
+
+EventBroker:
+  ## Emitted when every segment of a channel-level `send()` reached
+  ## `Confirmed`. Channel-level analogue of `MessageSentEvent`; the
+  ## `requestId` is the channel-layer parent returned by `send()`.
+  type ChannelMessageSentEvent* = object
+    channelId*: ChannelId
+    requestId*: RequestId
+
+EventBroker:
+  ## Emitted when a channel-level `send()` finalises with at least one
+  ## segment in `Failed`. Channel-level analogue of `MessageErrorEvent`.
+  type ChannelMessageErrorEvent* = object
+    channelId*: ChannelId
+    requestId*: RequestId
+    error*: string
diff --git a/logos_delivery/api/kernel_api.nim b/logos_delivery/api/kernel_api.nim
index 35cf7251f..01b0c30c0 100644
--- a/logos_delivery/api/kernel_api.nim
+++ b/logos_delivery/api/kernel_api.nim
@@ -1,203 +1,81 @@
-import std/options
 import chronos, results
-import brokers/event_broker
 
 import logos_delivery/api/types as api_types
 import logos_delivery/waku/waku_core/topics/pubsub_topic
 import logos_delivery/waku/waku_core/message
+import logos_delivery/waku/waku_core/subscription/push_handler
 import logos_delivery/waku/waku_store/common as store_types
 
-export event_broker
 export api_types, pubsub_topic, store_types
 
-type IKernel* = ref object of RootObj
+# Structural API contract for the Kernel surface, implemented by `Waku`
+# (ops in `waku/api/*`).
+type KernelApi* = concept w
+  # --- topic construction ---
+  buildContentTopic(
+    w, appName = string, appVersion = uint32, name = string, encoding = string
+  ) is Future[Result[ContentTopic, string]]
+  buildPubsubTopic(w, topicName = string) is Future[Result[PubsubTopic, string]]
+  defaultPubsubTopic(w) is Future[Result[PubsubTopic, string]]
 
-EventBroker:
-  # Internal event emitted when a message arrives from the network via any protocol
-  type MessageSeenEvent* = object
-    topic*: PubsubTopic
-    message*: WakuMessage
+  # --- relay ---
+  relayPublish(w, pubsubTopic = PubsubTopic, message = WakuMessage, timeoutMs = uint32) is
+    Future[Result[string, string]]
+  relaySubscribe(w, pubsubTopic = PubsubTopic) is Future[Result[bool, string]]
+  relayUnsubscribe(w, pubsubTopic = PubsubTopic) is Future[Result[bool, string]]
+  relayAddProtectedShard(w, clusterId = uint16, shardId = uint16, publicKey = string) is
+    Future[Result[bool, string]]
+  relayConnectedPeers(w, pubsubTopic = PubsubTopic) is
+    Future[Result[seq[string], string]]
+  relayPeersInMesh(w, pubsubTopic = PubsubTopic) is Future[Result[seq[string], string]]
+  relayNumPeersInMesh(w, pubsubTopic = PubsubTopic) is Future[Result[int, string]]
+  relayNumConnectedPeers(w, pubsubTopic = PubsubTopic) is Future[Result[int, string]]
 
-# --- topic construction ---
-method buildContentTopic*(
-    self: IKernel, appName: string, appVersion: uint32, name: string, encoding: string
-): Future[Result[ContentTopic, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.buildContentTopic not implemented")
+  # --- filter ---
+  filterSubscribe(
+    w,
+    pubsubTopic = PubsubTopic,
+    contentTopics = seq[ContentTopic],
+    pushHandler = FilterPushHandler,
+  ) is Future[Result[bool, string]]
+  filterUnsubscribe(w, pubsubTopic = PubsubTopic, contentTopics = seq[ContentTopic]) is
+    Future[Result[bool, string]]
+  filterUnsubscribeAll(w) is Future[Result[bool, string]]
 
-method buildPubsubTopic*(
-    self: IKernel, topicName: string
-): Future[Result[PubsubTopic, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.buildPubsubTopic not implemented")
+  # --- lightpush ---
+  lightpushPublish(w, pubsubTopic = PubsubTopic, message = WakuMessage) is
+    Future[Result[string, string]]
 
-method defaultPubsubTopic*(
-    self: IKernel
-): Future[Result[PubsubTopic, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.defaultPubsubTopic not implemented")
+  # --- store ---
+  storeQuery(w, request = StoreQueryRequest, peer = string, timeoutMs = int) is
+    Future[Result[StoreQueryResponse, string]]
 
-# --- relay ---
-method relayPublish*(
-    self: IKernel, pubsubTopic: PubsubTopic, message: WakuMessage, timeoutMs: uint32
-): Future[Result[int, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.relayPublish not implemented")
+  # --- peer management ---
+  connect(w, peers = seq[string], timeoutMs = uint32) is Future[Result[bool, string]]
+  disconnectPeerById(w, peerId = string) is Future[Result[bool, string]]
+  disconnectAllPeers(w) is Future[Result[bool, string]]
+  dialPeer(w, peerAddr = string, protocol = string, timeoutMs = int) is
+    Future[Result[bool, string]]
+  dialPeerById(w, peerId = string, protocol = string, timeoutMs = int) is
+    Future[Result[bool, string]]
+  peerIdsFromPeerstore(w) is Future[Result[seq[string], string]]
+  connectedPeersInfo(w) is Future[Result[seq[PeerConnInfo], string]]
+  connectedPeers(w) is Future[Result[seq[string], string]]
+  peerIdsByProtocol(w, protocol = string) is Future[Result[seq[string], string]]
 
-method relaySubscribe*(
-    self: IKernel, pubsubTopic: PubsubTopic
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.relaySubscribe not implemented")
+  # --- discovery ---
+  dnsDiscovery(w, enrTreeUrl = string, nameServer = string, timeoutMs = int) is
+    Future[Result[seq[string], string]]
+  discv5UpdateBootnodes(w, bootnodes = string) is Future[Result[bool, string]]
+  startDiscv5(w) is Future[Result[bool, string]]
+  stopDiscv5(w) is Future[Result[bool, string]]
+  peerExchangeRequest(w, numPeers = uint64) is Future[Result[int, string]]
 
-method relayUnsubscribe*(
-    self: IKernel, pubsubTopic: PubsubTopic
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.relayUnsubscribe not implemented")
-
-method relayAddProtectedShard*(
-    self: IKernel, clusterId: uint16, shardId: uint16, publicKey: string
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.relayAddProtectedShard not implemented")
-
-method relayConnectedPeers*(
-    self: IKernel, pubsubTopic: PubsubTopic
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.relayConnectedPeers not implemented")
-
-method relayPeersInMesh*(
-    self: IKernel, pubsubTopic: PubsubTopic
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.relayPeersInMesh not implemented")
-
-# --- filter ---
-method filterSubscribe*(
-    self: IKernel,
-    pubsubTopic: Option[PubsubTopic],
-    contentTopics: seq[ContentTopic],
-    peer: string,
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.filterSubscribe not implemented")
-
-method filterUnsubscribe*(
-    self: IKernel,
-    pubsubTopic: Option[PubsubTopic],
-    contentTopics: seq[ContentTopic],
-    peer: string,
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.filterUnsubscribe not implemented")
-
-method filterUnsubscribeAll*(
-    self: IKernel, peer: string
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.filterUnsubscribeAll not implemented")
-
-# --- lightpush ---
-method lightpushPublish*(
-    self: IKernel, pubsubTopic: PubsubTopic, message: WakuMessage, peer: string
-): Future[Result[string, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.lightpushPublish not implemented")
-
-# --- store ---
-method storeQuery*(
-    self: IKernel, request: StoreQueryRequest, peer: string, timeoutMs: int
-): Future[Result[StoreQueryResponse, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.storeQuery not implemented")
-
-# --- peer management ---
-method connect*(
-    self: IKernel, peers: seq[string], timeoutMs: uint32
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.connect not implemented")
-
-method disconnectPeerById*(
-    self: IKernel, peerId: string
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.disconnectPeerById not implemented")
-
-method disconnectAllPeers*(
-    self: IKernel
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.disconnectAllPeers not implemented")
-
-method dialPeer*(
-    self: IKernel, peerAddr: string, protocol: string, timeoutMs: int
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.dialPeer not implemented")
-
-method dialPeerById*(
-    self: IKernel, peerId: string, protocol: string, timeoutMs: int
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.dialPeerById not implemented")
-
-method peerIdsFromPeerstore*(
-    self: IKernel
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.peerIdsFromPeerstore not implemented")
-
-method connectedPeersInfo*(
-    self: IKernel
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.connectedPeersInfo not implemented")
-
-method connectedPeers*(
-    self: IKernel
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.connectedPeers not implemented")
-
-method peerIdsByProtocol*(
-    self: IKernel, protocol: string
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.peerIdsByProtocol not implemented")
-
-# --- discovery ---
-method dnsDiscovery*(
-    self: IKernel, enrTreeUrl: string, nameServer: string, timeoutMs: int
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.dnsDiscovery not implemented")
-
-method discv5UpdateBootnodes*(
-    self: IKernel, bootnodes: seq[string]
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.discv5UpdateBootnodes not implemented")
-
-method startDiscv5*(
-    self: IKernel
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.startDiscv5 not implemented")
-
-method stopDiscv5*(
-    self: IKernel
-): Future[Result[bool, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.stopDiscv5 not implemented")
-
-method peerExchangeRequest*(
-    self: IKernel, numPeers: uint64
-): Future[Result[int, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.peerExchangeRequest not implemented")
-
-# --- debug / info ---
-method version*(
-    self: IKernel
-): Future[Result[string, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.version not implemented")
-
-method listenAddresses*(
-    self: IKernel
-): Future[Result[seq[string], string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.listenAddresses not implemented")
-
-method myEnr*(
-    self: IKernel
-): Future[Result[string, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.myEnr not implemented")
-
-method myPeerId*(
-    self: IKernel
-): Future[Result[string, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.myPeerId not implemented")
-
-method metrics*(
-    self: IKernel
-): Future[Result[string, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.metrics not implemented")
-
-method pingPeer*(
-    self: IKernel, peerAddr: string, timeoutMs: int
-): Future[Result[int64, string]] {.async: (raises: []), base.} =
-  return err("Interface IKernel.pingPeer not implemented")
+  # --- debug / info ---
+  version(w) is Future[Result[string, string]]
+  listenAddresses(w) is Future[Result[seq[string], string]]
+  myEnr(w) is Future[Result[string, string]]
+  myPeerId(w) is Future[Result[string, string]]
+  metrics(w) is Future[Result[string, string]]
+  isOnline(w) is Future[Result[bool, string]]
+  pingPeer(w, peerAddr = string, timeoutMs = int) is Future[Result[int64, string]]
diff --git a/logos_delivery/api/logos_delivery_api.nim b/logos_delivery/api/logos_delivery_api.nim
index 162159d8e..708484553 100644
--- a/logos_delivery/api/logos_delivery_api.nim
+++ b/logos_delivery/api/logos_delivery_api.nim
@@ -1,33 +1,11 @@
-## `LogosDelivery` is the project entry point. It is a pure concentrator: it
-## owns exactly one instance of each API layer
-##
-##   Waku  <-  MessagingClient  <-  ReliableChannelManager
-##
-## and chains them together (each layer drives the one below it). Every layer
-## keeps its own, separate public API — `LogosDelivery` only wires them up and
-## drives the shared `new` / `start` / `stop` lifecycle.
+import chronos, results
 
-{.push raises: [].}
+# Structural API contract for the top-level entry point, implemented by
+# `LogosDelivery` (the aggregate owning one instance of each API layer).
+type LogosDeliveryApi* = concept ld
+  # --- lifecycle ---
+  start(ld) is Future[Result[void, string]]
+  stop(ld) is Future[Result[void, string]]
 
-import results, chronos
-import brokers/event_broker
-import types as api_types
-
-export api_types, event_broker
-
-type
-  ## Entry point. Holds one instance of each API layer.
-  ILogosDelivery* = ref object of RootObj
-
-EventBroker:
-  type EventConnectionStatusChange* = object
-    connectionStatus*: ConnectionStatus
-
-method start*(self: ILogosDelivery): Future[Result[void, string]] {.async, base.} =
-  return err("ILogosDelivery.start not implemented")
-
-method stop*(self: ILogosDelivery): Future[Result[void, string]] {.async, base.} =
-  return err("ILogosDelivery.stop not implemented")
-
-method isOnline*(self: ILogosDelivery): Future[Result[bool, string]] {.async, base.} =
-  return err("ILogosDelivery.isOnline not implemented")
+  # --- health ---
+  isOnline(ld) is Future[Result[bool, string]]
diff --git a/logos_delivery/api/messaging_client_api.nim b/logos_delivery/api/messaging_client_api.nim
index f29a5cb41..536ce94fa 100644
--- a/logos_delivery/api/messaging_client_api.nim
+++ b/logos_delivery/api/messaging_client_api.nim
@@ -1,49 +1,11 @@
 import chronos, results
-import brokers/event_broker
 
 import logos_delivery/api/types as api_types
-import logos_delivery/waku/waku_core/message
 
-export event_broker, api_types
+export api_types
 
-type IMessagingClient* = ref object of RootObj
-
-EventBroker:
-  # Event emitted when a message is sent to the network
-  type MessageSentEvent* = object
-    requestId*: RequestId
-    messageHash*: string
-
-EventBroker:
-  # Event emitted when a message send operation fails
-  type MessageErrorEvent* = object
-    requestId*: RequestId
-    messageHash*: string
-    error*: string
-
-EventBroker:
-  # Confirmation that a message has been correctly delivered to some neighbouring nodes.
-  type MessagePropagatedEvent* = object
-    requestId*: RequestId
-    messageHash*: string
-
-EventBroker:
-  # Event emitted when a message is received via Waku
-  type MessageReceivedEvent* = object
-    messageHash*: string
-    message*: WakuMessage
-
-method subscribe*(
-    self: IMessagingClient, contentTopic: ContentTopic
-): Future[Result[void, string]] {.async: (raises: []), base.} =
-  return err("Interface IMessagingClient.subscribe not implemented")
-
-method unsubscribe*(
-    self: IMessagingClient, contentTopic: ContentTopic
-): Result[void, string] {.base, raises: [].} =
-  return err("Interface IMessagingClient.unsubscribe not implemented")
-
-method send*(
-    self: IMessagingClient, envelope: MessageEnvelope
-): Future[Result[RequestId, string]] {.async: (raises: []), base.} =
-  return err("Interface IMessagingClient.send not implemented")
+# Structural API contract for a messaging client (ops in `messaging/api/*`).
+type MessagingApi* = concept c
+  subscribe(c, contentTopic = ContentTopic) is Future[Result[void, string]]
+  unsubscribe(c, contentTopic = ContentTopic) is Result[void, string]
+  send(c, envelope = MessageEnvelope) is Future[Result[RequestId, string]]
diff --git a/logos_delivery/api/reliable_channel_manager_api.nim b/logos_delivery/api/reliable_channel_manager_api.nim
index c5266972a..d50b57288 100644
--- a/logos_delivery/api/reliable_channel_manager_api.nim
+++ b/logos_delivery/api/reliable_channel_manager_api.nim
@@ -1,70 +1,23 @@
 import chronos, results
 
-import brokers/event_broker
-
 import logos_delivery/api/types as api_types
 import logos_delivery/channels/types as channel_types
 
-# The channel layer re-uses the messaging-layer message events (the `requestId`
-# is shared across layers), so it re-exports the messaging interface's event
-# surface and only adds the channel-level events that have no lower-layer
-# analogue (reassembled payload / senderId / channelId).
-import logos_delivery/api/messaging_client_api
+export api_types, channel_types
 
-export event_broker, api_types
-export channel_types, messaging_client_api
+type SendHandler* = proc(envelope: MessageEnvelope): Future[Result[RequestId, string]] {.
+  async: (raises: [CatchableError]), gcsafe
+.}
+  ## Egress dispatch boundary. Typically wraps `MessagingClient.send`;
+  ## tests inject a fake that records calls and returns canned
+  ## `RequestId`s so the send state machine can be exercised end-to-end
+  ## without a network.
 
-type
-  IReliableChannelManager* = ref object of RootObj
-
-  SendHandler* = proc(envelope: MessageEnvelope): Future[Result[RequestId, string]] {.
-    async: (raises: [CatchableError]), gcsafe
-  .}
-    ## Egress dispatch boundary. Typically wraps `MessagingClient.send`;
-    ## tests inject a fake that records calls and returns canned
-    ## `RequestId`s so the send state machine can be exercised end-to-end
-    ## without a network.
-
-EventBroker:
-  type ChannelMessageReceivedEvent* = object
-    channelId*: ChannelId
-    senderId*: SdsParticipantID
-    payload*: seq[byte]
-
-EventBroker:
-  ## Emitted when every segment of a channel-level `send()` reached
-  ## `Confirmed`. Channel-level analogue of `MessageSentEvent`; the
-  ## `requestId` is the channel-layer parent returned by `send()`.
-  type ChannelMessageSentEvent* = object
-    channelId*: ChannelId
-    requestId*: RequestId
-
-EventBroker:
-  ## Emitted when a channel-level `send()` finalises with at least one
-  ## segment in `Failed`. Channel-level analogue of `MessageErrorEvent`.
-  type ChannelMessageErrorEvent* = object
-    channelId*: ChannelId
-    requestId*: RequestId
-    error*: string
-
-method createReliableChannel*(
-    self: IReliableChannelManager,
-    channelId: ChannelId,
-    contentTopic: ContentTopic,
-    senderId: SdsParticipantID,
-    sendHandler: SendHandler = nil,
-): Result[ChannelId, string] {.base.} =
-  return err("Interface IReliableChannelManager.createReliableChannel not implemented")
-
-method closeChannel*(
-    self: IReliableChannelManager, channelId: ChannelId
-): Future[Result[void, string]] {.async: (raises: []), base.} =
-  return err("Interface IReliableChannelManager.closeChannel not implemented")
-
-method send*(
-    self: IReliableChannelManager,
-    channelId: ChannelId,
-    appPayload: seq[byte],
-    ephemeral: bool = false,
-): Future[Result[RequestId, string]] {.async: (raises: []), base.} =
-  return err("Interface IReliableChannelManager.send not implemented")
+# Structural API contract for the reliable-channel surface (ops in `channels/api/*`).
+type ReliableChannelApi* = concept c
+  createReliableChannel(
+    c, channelId = ChannelId, contentTopic = ContentTopic, senderId = SdsParticipantID
+  ) is Result[ChannelId, string]
+  closeChannel(c, channelId = ChannelId) is Future[Result[void, string]]
+  send(c, channelId = ChannelId, appPayload = seq[byte]) is
+    Future[Result[RequestId, string]]
diff --git a/logos_delivery/api/types.nim b/logos_delivery/api/types.nim
index 5757a8e82..97e7a11c9 100644
--- a/logos_delivery/api/types.nim
+++ b/logos_delivery/api/types.nim
@@ -26,6 +26,11 @@ type
     PartiallyConnected
     Connected
 
+  PeerConnInfo* = object ## structured connected-peer info for the api boundary
+    peerId*: string
+    protocols*: seq[string]
+    addresses*: seq[string]
+
 proc new*(T: typedesc[RequestId], rng: crypto.Rng): T =
   ## Generate a new RequestId using the provided RNG.
   RequestId(request_utils.generateRequestId(rng))
diff --git a/logos_delivery/channels/reliable_channel.nim b/logos_delivery/channels/reliable_channel.nim
index d06f74e36..06648a8f7 100644
--- a/logos_delivery/channels/reliable_channel.nim
+++ b/logos_delivery/channels/reliable_channel.nim
@@ -23,6 +23,8 @@ import libp2p/crypto/crypto as libp2p_crypto
 
 import logos_delivery/api/types
 import logos_delivery/api/reliable_channel_manager_api
+import logos_delivery/api/events/messaging_client_events
+import logos_delivery/api/events/reliable_channel_manager_events
 import logos_delivery/messaging/delivery_service/send_service
 import logos_delivery/waku/waku_core/topics
 
diff --git a/logos_delivery/channels/reliable_channel_manager.nim b/logos_delivery/channels/reliable_channel_manager.nim
index d3f671c2b..e8d579326 100644
--- a/logos_delivery/channels/reliable_channel_manager.nim
+++ b/logos_delivery/channels/reliable_channel_manager.nim
@@ -28,7 +28,7 @@ type
     ## channel API. Placeholder for now (segmentation / SDS / rate-limit defaults
     ## will move here in a follow-up PR); kept so each layer owns its own config.
 
-  ReliableChannelManager* = ref object of IReliableChannelManager
+  ReliableChannelManager* = ref object ## Implements `ReliableChannelApi`.
     channels*: Table[ChannelId, ReliableChannel] ## read by `channels/api.nim`
     messagingClient: MessagingClient ## The channel layer chains onto messaging.
     sendHandler*: SendHandler
diff --git a/logos_delivery/logos_delivery.nim b/logos_delivery/logos_delivery.nim
index d0fb33b90..0b161d6f7 100644
--- a/logos_delivery/logos_delivery.nim
+++ b/logos_delivery/logos_delivery.nim
@@ -11,9 +11,6 @@
 
 import results, chronos, chronicles
 
-import logos_delivery/api/logos_delivery_api
-export logos_delivery_api
-
 # Each layer has a core module (type + new/start/stop) and an api/ folder whose
 # modules each implement a differentiated set of operations, plus an events
 # surface. The concentrator re-exports them so library consumers get the full
@@ -31,8 +28,9 @@ import
 export
   topics, relay, subscriptions, filter, lightpush, store, peer_manager, discovery,
   debug, health, ping
-# `MessageSeenEvent` is surfaced via `export waku` (Kernel interface); the
-# remaining waku health events live here.
+# Kernel event surface (`MessageSeenEvent`) plus the remaining waku health events.
+import logos_delivery/api/events/kernel_events
+export kernel_events
 import logos_delivery/waku/api/events/health_events
 export health_events
 
@@ -41,7 +39,8 @@ import logos_delivery/messaging/messaging_client
 export messaging_client
 import logos_delivery/messaging/api/[subscription, send]
 export subscription, send
-# Message* events are surfaced via `export messaging_client` (messaging interface).
+import logos_delivery/api/events/messaging_client_events
+export messaging_client_events
 
 # Reliable Channel layer
 import logos_delivery/channels/reliable_channel_manager
@@ -50,8 +49,11 @@ import logos_delivery/channels/api/channel_lifecycle
 export channel_lifecycle
 import logos_delivery/channels/api/send as channel_send
 export channel_send
-# ChannelMessage* events are surfaced via `export reliable_channel_manager`.
+import logos_delivery/api/events/reliable_channel_manager_events
+export reliable_channel_manager_events
 
+import logos_delivery/api/logos_delivery_api
+export logos_delivery_api
 import logos_delivery/waku/factory/waku_conf
 import logos_delivery/waku/factory/app_callbacks
 import tools/confutils/cli_args
@@ -69,8 +71,7 @@ type
     messaging*: MessagingClientConf
     reliableChannel*: ReliableChannelManagerConf
 
-  LogosDelivery* = ref object of ILogosDelivery
-    ## Entry point. Holds one instance of each API layer.
+  LogosDelivery* = ref object ## Entry point. Holds one instance of each API layer.
     waku*: Waku
     messagingClient*: MessagingClient
     reliableChannelManager*: ReliableChannelManager
@@ -114,7 +115,7 @@ proc new*(
     )
   )
 
-method start*(self: LogosDelivery): Future[Result[void, string]] {.async.} =
+proc start*(self: LogosDelivery): Future[Result[void, string]] {.async.} =
   ## Starts each layer bottom-up: transport first, then messaging, then channels.
   if self.waku.isNil():
     return err("Waku node is not initialized")
@@ -134,7 +135,7 @@ method start*(self: LogosDelivery): Future[Result[void, string]] {.async.} =
 
   return ok()
 
-method stop*(self: LogosDelivery): Future[Result[void, string]] {.async.} =
+proc stop*(self: LogosDelivery): Future[Result[void, string]] {.async.} =
   ## Stops in reverse order so higher layers drain before their dependencies.
   await self.reliableChannelManager.stop()
   await self.messagingClient.stop()
@@ -144,7 +145,14 @@ method stop*(self: LogosDelivery): Future[Result[void, string]] {.async.} =
 
   return ok()
 
-method isOnline*(self: LogosDelivery): Future[Result[bool, string]] {.async.} =
+proc isOnline*(self: LogosDelivery): Future[Result[bool, string]] {.async.} =
   if self.waku.isNil():
     return err("Waku node is not initialized")
-  return ok(self.waku.healthMonitor.onlineMonitor.amIOnline())
+  return await self.waku.isOnline()
+
+# Compile-time check that each concrete type satisfies its API concept.
+static:
+  doAssert Waku is KernelApi
+  doAssert MessagingClient is MessagingApi
+  doAssert ReliableChannelManager is ReliableChannelApi
+  doAssert LogosDelivery is LogosDeliveryApi
diff --git a/logos_delivery/messaging/api/send.nim b/logos_delivery/messaging/api/send.nim
index 27c86d0ab..9a01c5f35 100644
--- a/logos_delivery/messaging/api/send.nim
+++ b/logos_delivery/messaging/api/send.nim
@@ -2,6 +2,7 @@
 import results, chronos, chronicles
 
 import logos_delivery/api/types
+import logos_delivery/api/events/messaging_client_events
 import logos_delivery/messaging/messaging_client
 import logos_delivery/waku/waku
 import logos_delivery/waku/api/subscriptions
diff --git a/logos_delivery/messaging/delivery_service/recv_service/recv_service.nim b/logos_delivery/messaging/delivery_service/recv_service/recv_service.nim
index 1090be223..d2c369d46 100644
--- a/logos_delivery/messaging/delivery_service/recv_service/recv_service.nim
+++ b/logos_delivery/messaging/delivery_service/recv_service/recv_service.nim
@@ -11,9 +11,9 @@ import
   logos_delivery/waku/waku,
   logos_delivery/waku/api/[store, subscriptions]
 import
-  logos_delivery/api/kernel_api, # MessageSeenEvent
-  logos_delivery/api/messaging_client_api, # MessageReceivedEvent
-  logos_delivery/api/logos_delivery_api # EventConnectionStatusChange
+  logos_delivery/api/events/kernel_events,
+    # MessageSeenEvent + EventConnectionStatusChange
+  logos_delivery/api/events/messaging_client_events # MessageReceivedEvent
 
 const MaxMessageLife = chronos.minutes(7) ## Max time we will keep track of rx messages
 
diff --git a/logos_delivery/messaging/delivery_service/send_service/send_service.nim b/logos_delivery/messaging/delivery_service/send_service/send_service.nim
index f482a2aff..037ad879b 100644
--- a/logos_delivery/messaging/delivery_service/send_service/send_service.nim
+++ b/logos_delivery/messaging/delivery_service/send_service/send_service.nim
@@ -10,7 +10,7 @@ import
   logos_delivery/waku/[waku_core, waku_store/common],
   logos_delivery/waku/waku,
   logos_delivery/waku/api/[store, subscriptions, publish]
-import logos_delivery/api/messaging_client_api
+import logos_delivery/api/events/messaging_client_events
 
 logScope:
   topics = "send service"
diff --git a/logos_delivery/messaging/messaging_client.nim b/logos_delivery/messaging/messaging_client.nim
index 4e02c7a82..e82c6d6fd 100644
--- a/logos_delivery/messaging/messaging_client.nim
+++ b/logos_delivery/messaging/messaging_client.nim
@@ -17,7 +17,7 @@ type
     ## follow-up PR. Today it only carries the p2p reliability toggle.
     useP2PReliability*: bool
 
-  MessagingClient* = ref object of IMessagingClient
+  MessagingClient* = ref object ## Implements `MessagingApi`.
     waku*: Waku ## The Waku kernel this layer drives; read by `messaging/api/*`.
     sendService*: SendService
     recvService*: RecvService
diff --git a/logos_delivery/waku/api/events/health_events.nim b/logos_delivery/waku/api/events/health_events.nim
index fbf00debb..9c49402f7 100644
--- a/logos_delivery/waku/api/events/health_events.nim
+++ b/logos_delivery/waku/api/events/health_events.nim
@@ -4,10 +4,7 @@ import logos_delivery/api/types
 import logos_delivery/waku/node/health_monitor/[protocol_health, topic_health]
 import logos_delivery/waku/waku_core/topics
 
-export protocol_health, topic_health
-
-# Note: `EventConnectionStatusChange` lives in `logos_delivery/api/logos_delivery_api`
-# (the top-level orchestrator interface owns the node-connectivity event).
+export event_broker, protocol_health, topic_health
 
 # Notify health changes to a subscribed topic
 # TODO: emit content topic health change events when subscribe/unsubscribe
diff --git a/logos_delivery/waku/api/peer_manager.nim b/logos_delivery/waku/api/peer_manager.nim
index 26de46594..3a73051b8 100644
--- a/logos_delivery/waku/api/peer_manager.nim
+++ b/logos_delivery/waku/api/peer_manager.nim
@@ -8,10 +8,7 @@ import libp2p/[peerid, peerstore]
 import logos_delivery/waku/waku
 import logos_delivery/waku/[waku_core, node/waku_node, node/peer_manager]
 
-type PeerConnInfo* = object ## structured connected-peer info for the api boundary
-  peerId*: string
-  protocols*: seq[string]
-  addresses*: seq[string]
+# `PeerConnInfo` is defined in `api/types` (surfaced here via `import waku`).
 
 proc connect*(
     self: Waku, peers: seq[string], timeoutMs: uint32
diff --git a/logos_delivery/waku/node/health_monitor/node_health_monitor.nim b/logos_delivery/waku/node/health_monitor/node_health_monitor.nim
index f59e0d7e6..8a4aadb4b 100644
--- a/logos_delivery/waku/node/health_monitor/node_health_monitor.nim
+++ b/logos_delivery/waku/node/health_monitor/node_health_monitor.nim
@@ -9,7 +9,7 @@ import
   libp2p/protocols/pubsub,
   libp2p/protocols/pubsub/rpc/messages,
   logos_delivery/api/types,
-  logos_delivery/api/logos_delivery_api, # EventConnectionStatusChange
+  logos_delivery/api/events/kernel_events, # EventConnectionStatusChange
   logos_delivery/waku/[
     waku_relay,
     api/events/health_events,
diff --git a/logos_delivery/waku/node/subscription_manager.nim b/logos_delivery/waku/node/subscription_manager.nim
index d0468749d..2c18a7b5e 100644
--- a/logos_delivery/waku/node/subscription_manager.nim
+++ b/logos_delivery/waku/node/subscription_manager.nim
@@ -22,7 +22,7 @@ import
     node/health_monitor/topic_health,
     node/health_monitor/connection_status,
   ]
-import logos_delivery/api/kernel_api # MessageSeenEvent
+import logos_delivery/api/events/kernel_events # MessageSeenEvent
 
 {.push raises: [].}
 
diff --git a/logos_delivery/waku/node/waku_node.nim b/logos_delivery/waku/node/waku_node.nim
index 3c2e41d8a..db90ab47c 100644
--- a/logos_delivery/waku/node/waku_node.nim
+++ b/logos_delivery/waku/node/waku_node.nim
@@ -62,7 +62,7 @@ import
     api/events/health_events,
     api/events/peer_events,
   ],
-  logos_delivery/api/kernel_api, # MessageSeenEvent
+  logos_delivery/api/events/kernel_events, # MessageSeenEvent
   logos_delivery/waku/discovery/waku_kademlia,
   logos_delivery/waku/net/[bound_ports, net_config],
   ./peer_manager,
diff --git a/logos_delivery/waku/node/waku_node/relay.nim b/logos_delivery/waku/node/waku_node/relay.nim
index ed039fb49..18a3f0f59 100644
--- a/logos_delivery/waku/node/waku_node/relay.nim
+++ b/logos_delivery/waku/node/waku_node/relay.nim
@@ -34,7 +34,7 @@ import
     node/subscription_manager,
     node/peer_manager,
   ]
-import logos_delivery/api/kernel_api # MessageSeenEvent
+import logos_delivery/api/events/kernel_events # MessageSeenEvent
 
 export waku_relay.WakuRelayHandler
 
diff --git a/logos_delivery/waku/waku.nim b/logos_delivery/waku/waku.nim
index 1dba0f633..29290483f 100644
--- a/logos_delivery/waku/waku.nim
+++ b/logos_delivery/waku/waku.nim
@@ -57,8 +57,8 @@ import
   ./factory/waku_conf,
   ./factory/waku_state_info
 
-# Surfaces the Kernel API interface (and its `MessageSeenEvent`) to consumers
-# of the Waku layer.
+# Surfaces the Kernel API interface to consumers of the Waku layer.
+# `MessageSeenEvent` now lives in `events/kernel_events` (surfaced by the concentrator).
 export kernel_api
 
 logScope:
@@ -67,7 +67,7 @@ logScope:
 # Git version in git describe format (defined at compile time)
 const git_version* {.strdefine.} = "n/a"
 
-type Waku* = ref object of IKernel
+type Waku* = ref object ## Implements `KernelApi` (ops in `waku/api/*`).
   stateInfo*: WakuStateInfo
   conf*: WakuConf
   rng*: crypto.Rng
diff --git a/tests/channels/test_reliable_channel_send_receive.nim b/tests/channels/test_reliable_channel_send_receive.nim
index 3a0a48c06..c20f0d0b0 100644
--- a/tests/channels/test_reliable_channel_send_receive.nim
+++ b/tests/channels/test_reliable_channel_send_receive.nim
@@ -10,7 +10,7 @@ import ../testlib/[common, wakucore, wakunode, testasync]
 import logos_delivery
 import logos_delivery/waku/[waku_node, waku_core]
 import logos_delivery/waku/factory/waku_conf
-import logos_delivery/api/messaging_client_api as waku_message_events
+import logos_delivery/api/events/messaging_client_events as waku_message_events
 import tools/confutils/cli_args
 
 import logos_delivery/channels/reliable_channel_manager