fix: isolate overlapping Human Gate loads

frontend/human-gates.js

@@ -10,6 +10,7 @@ function createHumanGates(options = {}) {
   let reviewSnapshot = [];
   let reviewIndex = -1;
   let loadedAccountKey = '';
+  let loadEpoch = 0;
   const decisionKeys = new Map();
   let decisionFlight = null;
 
@@ -80,6 +81,7 @@ function createHumanGates(options = {}) {
   }
 
   async function load() {
+    const epoch = ++loadEpoch;
     const accountKey = String(getAccountKey() || '').trim().toLowerCase();
     if (accountKey !== loadedAccountKey) {
       loadedAccountKey = accountKey;
@@ -92,12 +94,14 @@ function createHumanGates(options = {}) {
     if (cached) { queue = cached; render(); }
     try {
       const live = validSnapshot(await fetchJson('api/v1/human-gates'));
+      if (epoch !== loadEpoch || accountKey !== loadedAccountKey) return queue;
       if (!live) throw new Error('Human Gates response is invalid.');
       queue = { pending_count: live.pending_count, items: live.items.slice() };
       save(queue);
       render();
       return queue;
     } catch (error) {
+      if (epoch !== loadEpoch || accountKey !== loadedAccountKey) return queue;
       if (!cached) throw error;
       setText(nodes.status, 'Offline cached gate list · reconnect before deciding.');
       return queue;

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=[];