fix(simnet): improve error handling and port availability checks

.cargo/config.toml

@@ -1,3 +1,5 @@
 [alias]
 surfpool-install = "install --path crates/cli --locked --force --features supervisor_ui --features version_check"
 surfpool-install-dev = "install --path crates/cli --locked --force --features supervisor_ui"
+# useful for local builds that point to local txtx crates - prevents conflicts with the supervisor_ui feature
+surfpool-install-minimal = "install --path crates/cli --locked --force"

crates/cli/src/cli/mod.rs

@@ -243,7 +243,7 @@ pub struct StartSimnet {
     #[clap(long = "features-all", action=ArgAction::SetTrue, default_value = "false")]
     pub all_features: bool,
     /// A set of inputs to use for the runbook (eg. surfpool start --runbook-input myInputs.json)
-    #[arg(long = "runbook-input", short = 'i', default_value = "./txtx.yml")]
+    #[arg(long = "runbook-input", short = 'i')]
     pub runbook_input: Vec<String>,
 }
 

crates/cli/src/cli/simnet/mod.rs

@@ -5,7 +5,6 @@ use std::{
         atomic::{AtomicBool, Ordering},
         mpsc,
     },
-    thread::sleep,
     time::Duration,
 };
 
@@ -137,6 +136,7 @@ pub async fn handle_start_local_surfnet_command(
     let simnet_commands_tx_copy = simnet_commands_tx.clone();
     let config_copy = config.clone();
 
+    let simnet_events_tx_for_thread = simnet_events_tx.clone();
     let _handle = hiro_system_kit::thread_named("simnet")
         .spawn(move || {
             let future = start_local_surfnet(
@@ -148,17 +148,19 @@ pub async fn handle_start_local_surfnet_command(
                 geyser_events_rx,
             );
             if let Err(e) = hiro_system_kit::nestable_block_on(future) {
-                error!("Simnet exited with error: {e}");
-                sleep(Duration::from_millis(500));
-                std::process::exit(1);
+                // Send the error through the event channel so the main thread can handle it
+                let _ = simnet_events_tx_for_thread.send(SimnetEvent::Aborted(e.to_string()));
             }
             Ok::<(), String>(())
         })
         .map_err(|e| format!("{}", e))?;
 
     loop {
         match simnet_events_rx.recv() {
-            Ok(SimnetEvent::Aborted(error)) => return Err(error),
+            Ok(SimnetEvent::Aborted(error)) => {
+                eprintln!("Error: {}", error);
+                return Err(error);
+            }
             Ok(SimnetEvent::Shutdown) => return Ok(()),
             Ok(SimnetEvent::Ready) => break,
             _other => continue,

crates/core/src/runloops/mod.rs

@@ -54,6 +54,27 @@ use crate::{
 
 const BLOCKHASH_SLOT_TTL: u64 = 75;
 
+/// Checks if a port is available for binding.
+fn check_port_availability(addr: SocketAddr, server_type: &str) -> Result<(), String> {
+    match std::net::TcpListener::bind(addr) {
+        Ok(_listener) => Ok(()),
+        Err(e) if e.kind() == std::io::ErrorKind::AddrInUse => {
+            let msg = format!(
+                "{} port {} is already in use. Try --port or --ws-port to use a different port.",
+                server_type,
+                addr.port()
+            );
+            eprintln!("Error: {}", msg);
+            Err(msg)
+        }
+        Err(e) => {
+            let msg = format!("Failed to bind {} server to {}: {}", server_type, addr, e);
+            eprintln!("Error: {}", msg);
+            Err(msg)
+        }
+    }
+}
+
 pub async fn start_local_surfnet_runloop(
     svm_locker: SurfnetSvmLocker,
     config: SurfpoolConfig,
@@ -721,6 +742,20 @@ async fn start_rpc_servers_runloop(
     ),
     String,
 > {
+    let rpc_addr: SocketAddr = config
+        .rpc
+        .get_rpc_base_url()
+        .parse()
+        .map_err(|e: std::net::AddrParseError| e.to_string())?;
+    let ws_addr: SocketAddr = config
+        .rpc
+        .get_ws_base_url()
+        .parse()
+        .map_err(|e: std::net::AddrParseError| e.to_string())?;
+
+    check_port_availability(rpc_addr, "RPC")?;
+    check_port_availability(ws_addr, "WebSocket")?;
+
     let (plugin_manager_commands_tx, plugin_manager_commands_rx) = unbounded();
     let simnet_events_tx = svm_locker.simnet_events_tx();
 
@@ -762,9 +797,6 @@ async fn start_http_rpc_server_runloop(
         io.extend_with(rpc::admin::SurfpoolAdminRpc.to_delegate());
     }
 
-    let _ = std::net::TcpListener::bind(server_bind)
-        .map_err(|e| format!("Failed to start RPC server: {}", e))?;
-
     let _handle = hiro_system_kit::thread_named("RPC Handler")
         .spawn(move || {
             let server = match ServerBuilder::new(io)