diff --git a/src/router.rs b/src/router.rs
index 365ab41..bc531fc 100644
--- a/src/router.rs
+++ b/src/router.rs
@@ -1,9 +1,11 @@
-use std::{collections::HashSet, sync::Arc};
+use std::{collections::{HashSet, HashMap}, sync::Arc};
 
 use base64::Engine;
 use base64::engine::general_purpose::STANDARD as BASE64_STANDARD;
 use serde_json::{Value, json};
-use tokio::sync::Semaphore;
+use tokio::sync::{Semaphore, Mutex};
+use std::hash::{Hash, Hasher};
+use std::collections::hash_map::DefaultHasher;
 
 use crate::{
     clients::{Destination, MyceliumClient, SupervisorClient},
@@ -23,6 +25,88 @@ pub struct RouterConfig {
     pub transport_poll_timeout_secs: u64,  // e.g. 300 (5 minutes)
 }
 
+/*
+SupervisorClient reuse cache (Router-local):
+
+Rationale:
+- SupervisorClient maintains an internal JSON-RPC id_counter per instance.
+- Rebuilding a client for each message resets this counter, causing inner JSON-RPC ids to restart at 1.
+- We reuse one SupervisorClient per (destination, topic, secret) to preserve monotonically increasing ids.
+
+Scope:
+- Cache is per Router loop (and a separate one for the inbound listener).
+- If cross-loop/process reuse becomes necessary later, promote to a process-global cache.
+
+Keying:
+- Key: destination + topic + secret-presence (secret content hashed; not stored in plaintext).
+
+Concurrency:
+- tokio::Mutex protects a HashMap<String, Arc<SupervisorClient>>.
+- Values are Arc so call sites clone cheaply and share the same id_counter.
+*/
+#[derive(Clone)]
+struct SupervisorClientCache {
+    map: Arc<Mutex<HashMap<String, Arc<SupervisorClient>>>>,
+}
+
+impl SupervisorClientCache {
+    fn new() -> Self {
+        Self {
+            map: Arc::new(Mutex::new(HashMap::new())),
+        }
+    }
+
+    fn make_key(dest: &Destination, topic: &str, secret: &Option<String>) -> String {
+        let dst = match dest {
+            Destination::Ip(ip) => format!("ip:{ip}"),
+            Destination::Pk(pk) => format!("pk:{pk}"),
+        };
+        // Hash the secret to avoid storing plaintext in keys while still differentiating values
+        let sec_hash = match secret {
+            Some(s) if !s.is_empty() => {
+                let mut hasher = DefaultHasher::new();
+                s.hash(&mut hasher);
+                format!("s:{}", hasher.finish())
+            }
+            _ => "s:none".to_string(),
+        };
+        format!("{dst}|t:{topic}|{sec_hash}")
+    }
+
+    async fn get_or_create(
+        &self,
+        mycelium: Arc<MyceliumClient>,
+        dest: Destination,
+        topic: String,
+        secret: Option<String>,
+    ) -> Arc<SupervisorClient> {
+        let key = Self::make_key(&dest, &topic, &secret);
+
+        {
+            let guard = self.map.lock().await;
+            if let Some(existing) = guard.get(&key) {
+                tracing::debug!(target: "router", cache="supervisor", hit=true, %topic, secret = %if secret.is_some() { "set" } else { "none" }, "SupervisorClient cache lookup");
+                return existing.clone();
+            }
+        }
+
+        let mut guard = self.map.lock().await;
+        if let Some(existing) = guard.get(&key) {
+            tracing::debug!(target: "router", cache="supervisor", hit=true, %topic, secret = %if secret.is_some() { "set" } else { "none" }, "SupervisorClient cache lookup (double-checked)");
+            return existing.clone();
+        }
+        let client = Arc::new(SupervisorClient::new_with_client(
+            mycelium,
+            dest,
+            topic.clone(),
+            secret.clone(),
+        ));
+        guard.insert(key, client.clone());
+        tracing::debug!(target: "router", cache="supervisor", hit=false, %topic, secret = %if secret.is_some() { "set" } else { "none" }, "SupervisorClient cache insert");
+        client
+    }
+}
+
 /// Start background router loops, one per context.
 /// Each loop:
 /// - BRPOP msg_out with 1s timeout
@@ -49,6 +133,8 @@ pub fn start_router(service: AppService, cfg: RouterConfig) -> Vec<tokio::task::
                 }
             };
 
+            let cache = Arc::new(SupervisorClientCache::new());
+
             loop {
                 // Pop next message key (blocking with timeout)
                 match service_cloned.brpop_msg_out(ctx_id, 1).await {
@@ -69,11 +155,12 @@ pub fn start_router(service: AppService, cfg: RouterConfig) -> Vec<tokio::task::
                         let cfg_task = cfg_cloned.clone();
                         tokio::spawn({
                             let mycelium = mycelium.clone();
+                            let cache = cache.clone();
                             async move {
                                 // Ensure permit is dropped at end of task
                                 let _permit = permit;
                                 if let Err(e) =
-                                    deliver_one(&service_task, &cfg_task, ctx_id, &key, mycelium)
+                                    deliver_one(&service_task, &cfg_task, ctx_id, &key, mycelium, cache.clone())
                                         .await
                                 {
                                     error!(context_id=ctx_id, key=%key, error=%e, "Delivery error");
@@ -104,6 +191,7 @@ async fn deliver_one(
     context_id: u32,
     msg_key: &str,
     mycelium: Arc<MyceliumClient>,
+    cache: Arc<SupervisorClientCache>,
 ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
     // Parse "message:{caller_id}:{id}"
     let (caller_id, id) = parse_message_key(msg_key)
@@ -143,12 +231,14 @@ async fn deliver_one(
     let dest_for_poller = dest.clone();
     let topic_for_poller = cfg.topic.clone();
     let secret_for_poller = runner.secret.clone();
-    let client = SupervisorClient::new_with_client(
-        mycelium.clone(),
-        dest.clone(),
-        cfg.topic.clone(),
-        runner.secret.clone(),
-    );
+    let client = cache
+        .get_or_create(
+            mycelium.clone(),
+            dest.clone(),
+            cfg.topic.clone(),
+            runner.secret.clone(),
+        )
+        .await;
 
     // Build supervisor method and params from Message
     let method = msg.message.clone();
@@ -251,12 +341,14 @@ async fn deliver_one(
                             // if matches!(s, TransportStatus::Read)
                             // && let Some(job_id) = job_id_opt
                             if let Some(job_id) = job_id_opt {
-                                let sup = SupervisorClient::new_with_client(
-                                    client.clone(),
-                                    sup_dest.clone(),
-                                    sup_topic.clone(),
-                                    secret_for_poller.clone(),
-                                );
+                                let sup = cache
+                                    .get_or_create(
+                                        client.clone(),
+                                        sup_dest.clone(),
+                                        sup_topic.clone(),
+                                        secret_for_poller.clone(),
+                                    )
+                                    .await;
                                 match sup.job_status_with_ids(job_id.to_string()).await {
                                     Ok((_out_id, inner_id)) => {
                                         // Correlate this status request to the message/job
@@ -425,6 +517,8 @@ pub fn start_inbound_listener(
             }
         };
 
+        let cache = Arc::new(SupervisorClientCache::new());
+
         loop {
             // Poll for inbound supervisor messages on the configured topic
             match mycelium.pop_message(Some(false), Some(20), None).await {
@@ -599,12 +693,14 @@ pub fn start_inbound_listener(
                                                                 } else {
                                                                     Destination::Ip(runner.address)
                                                                 };
-                                                                let sup = SupervisorClient::new_with_client(
-                                                                    mycelium.clone(),
-                                                                    dest,
-                                                                    cfg.topic.clone(),
-                                                                    runner.secret.clone(),
-                                                                );
+                                                                let sup = cache
+                                                                    .get_or_create(
+                                                                        mycelium.clone(),
+                                                                        dest,
+                                                                        cfg.topic.clone(),
+                                                                        runner.secret.clone(),
+                                                                    )
+                                                                    .await;
                                                                 match sup
                                                                     .job_result_with_ids(
                                                                         job_id.to_string(),