feat: harden multi-host runtime coordination

src/govoplan_core/core/runtime_coordination.py

@@ -166,9 +166,7 @@ def runtime_identity(
             for item in str(getattr(settings, "celery_queues", "") or "").split(",")
             if item.strip()
         )
-    composition_hash = hashlib.sha256(
-        json.dumps(sorted(module_ids), separators=(",", ":")).encode("utf-8")
-    ).hexdigest()
+    composition_hash = runtime_composition_hash(module_ids)
     return RuntimeIdentity(
         installation_id=installation_id,
         node_id=effective_node_id,
@@ -180,6 +178,12 @@ def runtime_identity(
     )
 
 
+def runtime_composition_hash(module_ids: tuple[str, ...]) -> str:
+    return hashlib.sha256(
+        json.dumps(sorted(set(module_ids)), separators=(",", ":")).encode("utf-8")
+    ).hexdigest()
+
+
 def register_runtime_node(
     session: Session,
     identity: RuntimeIdentity,