First test kinda working

substrate/src/config.rs

@@ -7,6 +7,7 @@ use serde::{Deserialize, Serialize};
 pub struct AppConfig {
     pub network: QuicConfig,
     pub simulation: SimulationConfig,
+    pub observability: ObservabilityConfig,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -23,6 +24,15 @@ pub struct QuicConfig {
     pub server_key: String,
 }
 
+#[derive(Debug, Serialize, Deserialize)]
+pub struct ObservabilityConfig {
+    /// When true, install the Prometheus exporter at startup. Disable for
+    /// environments where the metrics port collides or scraping is undesired.
+    pub metrics_enabled: bool,
+    /// Bind address for the `/metrics` HTTP listener.
+    pub metrics_listen: String,
+}
+
 impl Default for AppConfig {
     fn default() -> Self {
         Self {
@@ -36,6 +46,10 @@ impl Default for AppConfig {
                 tick_rate_hz: 60,
                 max_entities: 10000,
             },
+            observability: ObservabilityConfig {
+                metrics_enabled: true,
+                metrics_listen: "0.0.0.0:9100".to_string(),
+            },
         }
     }
 }