fix: serialize Week-to-Today replay across tabs

tests/test_week_plan_frontend.py

@@ -398,6 +398,43 @@ console.log(JSON.stringify({queuedFirst,queuedSecond,resumed,confirmed,delivered
     assert result["state"]["revision"] == 9
 
 
+def test_week_controller_allows_only_one_tab_to_replay_the_shared_pull_queue():
+    result = run_controller("""
+const values=new Map(),held=new Set();
+const storage={getItem:key=>values.get(key)||null,setItem:(key,value)=>values.set(key,value),removeItem:key=>values.delete(key)};
+const coordinator={runExclusive:async(queue,work)=>{
+ if(held.has(queue))return {lease_skipped:true};
+ held.add(queue);try{return await work();}finally{held.delete(queue);}
+}};
+let offline=true,posts=0,release;
+const gate=new Promise(resolve=>release=resolve);
+const fetchJson=async(_url,options={})=>{
+ if(offline)throw new Error('connection lost');
+ posts+=1;await gate;
+ const body=JSON.parse(options.body);
+ return {today:{revision:5,ids:['active',body.identity],capacity_minutes:180,estimates:{active:30,[body.identity]:35}},
+   week:{revision:8,timezone:'UTC',days:[{plan_date:'2026-08-21',ids:[],capacity_minutes:150,estimates:{}}]}};
+};
+const options={storage,coordinator,getLogin:()=> 'timmy',fetchJson,localDate:()=> '2026-08-20',timeZone:()=> 'UTC'};
+const source=createWeekPlan(options);source.adopt({revision:7,timezone:'UTC',days:[{plan_date:'2026-08-21',ids:['first'],capacity_minutes:150,estimates:{first:35}}]});
+await source.pullItem('first',{revision:4,ids:['active'],capacity_minutes:180,estimates:{active:30}},'pull-first');
+offline=false;
+const first=createWeekPlan(options),second=createWeekPlan(options);
+const firstFlush=first.flushPull();
+await Promise.resolve();
+setImmediate(release);
+const skipped=await second.flushPull();
+release();
+const confirmed=await firstFlush;
+console.log(JSON.stringify({posts,skipped,confirmed,pending:first.pendingPull()}));
+""")
+
+    assert result["posts"] == 1
+    assert result["skipped"]["lease_skipped"] is True
+    assert result["confirmed"]["sync_pending"] is False
+    assert result["pending"] is None
+
+
 def test_week_controller_resumes_server_truth_when_a_fifo_head_conflicts():
     result = run_controller("""
 const values=new Map();