Architecture#

Where this module sits in the stack, and how much of that stack a given node actually mounts.

Layers#

A message passes through four layers on its way out:

Logos Core  ·  your module or UI
     │  calls delivery_module methods
     ▼
delivery_module            ← this repository, a Qt plugin
     │  C FFI
     ▼
liblogosdelivery
     │  Nim API
     ▼
logos-delivery             ← the node implementation

This repository is the middle box. It owns no protocol logic: it adapts the universal Logos module API onto liblogosdelivery’s C FFI, and turns the callbacks coming back the other way into typed events. Everything about how messages actually travel is decided by logos-delivery.

That division is why the configuration you pass to createNode is handed through verbatim — logos-delivery owns the grammar, and this module does not interpret it.

What a node mounts#

createNode’s entryLayer decides how much of the stack comes up:

`entryLayer`	What you get
`"kernel"`	Transport node only.
`"messaging"`	Kernel plus the messaging client.
`"channels"`	Kernel, messaging, and reliable channels. The default.

The layer you pick determines which methods work. On a kernel-only node, send, subscribe and the channel* methods fail with “node has no messaging client” or “no reliable channel manager”. getNodeInfo, storeQuery and metrics keep working.

The concrete configuration shapes — an app developer’s full stack, a node operator’s public service node, a self-hosted network — are documented with createNode in the API reference.

Plugin-hosted discovery#

With pluginKadDiscovery on, logos-delivery delegates kademlia service discovery to this module, which hosts it on libp2p_module. After createNode the module asks the node (logosdelivery_get_discovery_requirements) whether a plugin is expected and which DHT bootstrap peers its configuration resolved, presets included. It sets libp2p_module up from that answer — the peers as bootstrapNodes, mountKad and mountServiceDiscovery on — laid over libp2p’s own LIBP2P_MODULE_CONFIG.

libp2p is first contacted on the first discovery call after start, not at createNode, so a missing module or a bad bootstrap set surfaces there. Every bootstrap peer is handed over. libp2p dials the set inside its start, whose call deadline is a fixed 10 s; a start that outlasts it carries on and is not issued again.

Set LD_DISCO_TRACE to a file path to log every call across the plugin boundary; logos-core discards a module’s stderr, so that file is the only view into it.