diff --git a/config/runtime.exs b/config/runtime.exs
index c6473cbe..f2578331 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -383,12 +383,24 @@ if config_env() == :prod do
   # cluster-elected leader actually connects (`:global` registration
   # in `Microwaveprop.Pskr.Client`). Set `PSKR_MQTT_ENABLED=false`
   # to kill the entire feature without code change.
+  #
+  # Backfill pods opt out unconditionally — they share the libcluster
+  # `app=prop` selector with the hot pods, so without this gate the
+  # backfill pod can win :global election (FCFS during a rollout)
+  # and pin the MQTT client onto a node that's also under heavy
+  # batch-job load. MQTT is real-time; backfill is bursty CPU; the
+  # two don't mix on the same pod.
+  pskr_default = prop_role != "backfill"
+
   case System.get_env("PSKR_MQTT_ENABLED") do
     disabled when disabled in ["0", "false", "FALSE"] ->
       config :microwaveprop, :pskr_mqtt_enabled, false
 
-    _ ->
+    enabled when enabled in ["1", "true", "TRUE"] ->
       config :microwaveprop, :pskr_mqtt_enabled, true
+
+    _ ->
+      config :microwaveprop, :pskr_mqtt_enabled, pskr_default
   end
 
   # Optional secondary repo for read-only access to aprs.me's database.