diff --git a/lib/runtime/src/discovery/kube.rs b/lib/runtime/src/discovery/kube.rs
index 89c1e03a838b..40991161742d 100644
--- a/lib/runtime/src/discovery/kube.rs
+++ b/lib/runtime/src/discovery/kube.rs
@@ -25,6 +25,14 @@ use std::collections::HashSet;
 use std::sync::Arc;
 use tokio::sync::RwLock;
 
+fn validate_kubernetes_publisher_id(publisher_id: u64) -> Result<()> {
+    if i64::try_from(publisher_id).is_err() {
+        anyhow::bail!("Kubernetes discovery publisher ID {publisher_id} exceeds i64::MAX");
+    }
+
+    Ok(())
+}
+
 /// Kubernetes-based discovery client
 #[derive(Clone)]
 pub struct KubeDiscoveryClient {
@@ -115,6 +123,13 @@ impl Discovery for KubeDiscoveryClient {
     }
 
     async fn register_internal(&self, spec: DiscoverySpec) -> Result<DiscoveryInstance> {
+        match &spec {
+            DiscoverySpec::EventChannel { publisher_id, .. }
+            | DiscoverySpec::EventSource { publisher_id, .. } => {
+                validate_kubernetes_publisher_id(*publisher_id)?;
+            }
+            _ => {}
+        }
         let instance = spec.into_instance(self.instance_id());
         let instance_id = instance.instance_id();
 
@@ -503,3 +518,14 @@ impl Discovery for KubeDiscoveryClient {
         Ok(Box::pin(stream))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn publisher_ids_must_fit_kubernetes_integer_range() {
+        assert!(validate_kubernetes_publisher_id(i64::MAX as u64).is_ok());
+        assert!(validate_kubernetes_publisher_id((i64::MAX as u64) + 1).is_err());
+    }
+}
diff --git a/lib/runtime/src/discovery/kube/crd.rs b/lib/runtime/src/discovery/kube/crd.rs
index 1be5de2d98af..23d9f1426893 100644
--- a/lib/runtime/src/discovery/kube/crd.rs
+++ b/lib/runtime/src/discovery/kube/crd.rs
@@ -176,12 +176,19 @@ mod tests {
                 endpoint: endpoint.clone(),
             },
             topic: "kv-events".to_string(),
-            publisher_id: 205,
+            publisher_id: i64::MAX as u64,
             metadata: serde_json::json!({"worker_id": 7, "dp_rank": 0}),
         };
         metadata.register_event_source(source.clone()).unwrap();
 
         let cr = build_cr("test-pod", "test-pod", "pod-uid", &metadata).unwrap();
+        let publisher_id = cr.spec.data["event_sources"]
+            .as_object()
+            .and_then(|sources| sources.values().next())
+            .and_then(|source| source.get("publisher_id"))
+            .expect("serialized event source publisher ID");
+        assert!(publisher_id.is_i64());
+
         let round_trip: DiscoveryMetadata = serde_json::from_value(cr.spec.data).unwrap();
 
         assert_eq!(
diff --git a/lib/runtime/src/transports/event_plane/mod.rs b/lib/runtime/src/transports/event_plane/mod.rs
index 1b7fae8543ad..fcc2ac53da80 100644
--- a/lib/runtime/src/transports/event_plane/mod.rs
+++ b/lib/runtime/src/transports/event_plane/mod.rs
@@ -259,6 +259,11 @@ impl Stream for DeduplicatingStream {
     }
 }
 
+/// Keep the shared wire, channel, and source publisher ID representable in Kubernetes metadata.
+fn discovery_safe_publisher_id(random_id: u64) -> u64 {
+    random_id & (i64::MAX as u64)
+}
+
 /// Event publisher for a specific topic.
 pub struct EventPublisher {
     transport_kind: EventTransportKind,
@@ -387,9 +392,11 @@ impl EventPublisher {
         // can host multiple publishers for the same scope/topic, each with its
         // own ZMQ endpoint and sequence space, so the process ID is not unique
         // enough here.
-        let publisher_id = rand::rngs::OsRng
-            .try_next_u64()
-            .map_err(|error| anyhow::anyhow!("failed to generate publisher ID: {error}"))?;
+        let publisher_id = discovery_safe_publisher_id(
+            rand::rngs::OsRng
+                .try_next_u64()
+                .map_err(|error| anyhow::anyhow!("failed to generate publisher ID: {error}"))?,
+        );
         let discovery = Some(drt.discovery());
         let runtime_handle = drt.runtime().secondary();
         let subject = scope.subject(&topic);
@@ -915,6 +922,12 @@ mod tests {
     use super::*;
     use crate::config::environment_names::zmq_broker as broker_env;
 
+    #[test]
+    fn publisher_ids_fit_kubernetes_discovery_integer_range() {
+        assert_eq!(discovery_safe_publisher_id(42), 42);
+        assert!(i64::try_from(discovery_safe_publisher_id(u64::MAX)).is_ok());
+    }
+
     #[test]
     fn direct_zmq_topology_selection_is_narrow() {
         let lookup = |url: Option<&str>, enabled: Option<&str>| {