simln-lib/feat: add ldk-server backend support

Add `LdkNode` as a new `LightningNode` implementation backed by
ldk-server-client over gRPC-over-HTTPS. Supports keysend via
`spontaneous_send`, payment tracking via polling `get_payment_details`,
graph queries, and channel capacity reporting.

Wire up `NodeConnection::Ldk` in sim-cli parsing so ldk-server nodes
can be specified in sim.json alongside LND, CLN, and Eclair nodes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: randomlogin

Cargo.lock

@@ -9,9 +9,9 @@ use simln_lib::sim_node::{
     SimGraph, SimNode, SimulatedChannel,
 };
 use simln_lib::{
-    cln, cln::ClnNode, eclair, eclair::EclairNode, lnd, lnd::LndNode, serializers,
-    ActivityDefinition, Amount, Interval, LightningError, LightningNode, NodeId, NodeInfo,
-    Simulation, SimulationCfg, WriteResults,
+    cln, cln::ClnNode, eclair, eclair::EclairNode, ldk, ldk::LdkNode, lnd, lnd::LndNode,
+    serializers, ActivityDefinition, Amount, Interval, LightningError, LightningNode, NodeId,
+    NodeInfo, Simulation, SimulationCfg, WriteResults,
 };
 use simln_lib::{ShortChannelID, SimulationError};
 use std::collections::HashMap;
@@ -160,6 +160,7 @@ pub enum NodeConnection {
     Lnd(lnd::LndConnection),
     Cln(cln::ClnConnection),
     Eclair(eclair::EclairConnection),
+    Ldk(ldk::LdkConnection),
 }
 
 /// Data structure that is used to parse information from the simulation file. It is used to
@@ -396,6 +397,7 @@ async fn get_clients(
             NodeConnection::Lnd(c) => Arc::new(Mutex::new(LndNode::new(c).await?)),
             NodeConnection::Cln(c) => Arc::new(Mutex::new(ClnNode::new(c).await?)),
             NodeConnection::Eclair(c) => Arc::new(Mutex::new(EclairNode::new(c).await?)),
+            NodeConnection::Ldk(c) => Arc::new(Mutex::new(LdkNode::new(c).await?)),
         };
 
         let node_info = node.lock().await.get_info().clone();

sim-cli/src/parsing.rs

@@ -33,6 +33,7 @@ rand_distr = "0.4.3"
 rand_chacha = "0.3.1"
 reqwest = { version = "0.12", features = ["json", "multipart"] }
 tokio-util = { version = "0.7.13", features = ["rt"] }
+ldk-server-client = { git = "https://github.com/lightningdevkit/ldk-server", rev = "570ed527535da0ec1dae431fac3ce46e5e6a468f" }
 
 [dev-dependencies]
 ntest = "0.9.0"