fix: isolate overlapping Human Gate loads

tests/test_human_gates_frontend.py

@@ -94,6 +94,18 @@ const gates=createHumanGates({storage,getLogin:()=> 'timmy',getAccountKey:()=>ac
     assert "secret" not in output["html"]
 
 
+def test_stale_account_load_cannot_overwrite_new_account_queue_or_cache():
+    output = run_node(r"""
+const values=new Map(); const storage={getItem:k=>values.get(k)||null,setItem:(k,v)=>values.set(k,v)};
+let account='1:timmy', resolveA, resolveB;
+const responseA=new Promise(resolve=>resolveA=resolve), responseB=new Promise(resolve=>resolveB=resolve);
+const gates=createHumanGates({storage,getLogin:()=> 'timmy',getAccountKey:()=>account,isOnline:()=>true,nodes:{count:{},list:{innerHTML:''},status:{},panel:{}},location:{hash:''},fetchJson:()=>account.startsWith('1:')?responseA:responseB});
+(async()=>{const loadA=gates.load();account='2:timmy';const loadB=gates.load();resolveB({pending_count:1,items:[{id:'b',title:'B gate',candidate_hash:'bhash'}]});await loadB;resolveA({pending_count:1,items:[{id:'a-secret',title:'A secret',candidate_hash:'asecret'}]});await loadA;process.stdout.write(JSON.stringify({snapshot:gates.snapshot(),cached:JSON.parse(values.get('stackchain.human-gates.v1:2:timmy'))}));})();
+""")
+    assert [item["id"] for item in output["snapshot"]["items"]] == ["b"]
+    assert [item["id"] for item in output["cached"]["items"]] == ["b"]
+
+
 def test_decision_retry_reuses_the_same_idempotency_key():
     output = run_node(r"""
 let attempts=0; const keys=[];