Add scoped native history and window agent controls

tests/history-navigation.test.mjs

@@ -19,3 +19,14 @@ test('unexpected final URL and mainframe load failure reject; timeout stops',asy
 
 test('missing positive native context proof denies history before any side effect',async()=>{const c=fixture();await assert.rejects(run(c,{current:async()=>undefined}),/context changed/);assert.equal(c.calls,0);});
 test('context guards distinguish captured state before dispatch from intentional navigation after',async()=>{const c=fixture(),phases=[];const p=run(c,{current:phase=>{phases.push(phase);return phase==='before'?c.calls===0:c.calls===1;}});await dispatched(c);c.emit('did-finish-load');assert.equal((await p).completed,true);assert.ok(phases.includes('before')&&phases.includes('after'));});
+
+test('indexed history compares exact snapshot immediately before native dispatch and never retries',async()=>{
+ const c=fixture(),snapshot=()=>({activeIndex:c.index,entries:[{url:'https://example.test/one',title:'One'},{url:'https://example.test/two',title:'Two'}]}),binding=JSON.stringify(snapshot());
+ const p=run(c,{action:'index',index:0,getSnapshot:snapshot,historyBinding:binding});await dispatched(c);c.emit('did-finish-load');assert.equal((await p).url,'https://example.test/one');assert.equal(c.calls,1);
+ const changed=fixture();let title='Two';const getSnapshot=()=>({activeIndex:changed.index,entries:[{url:'https://example.test/one',title:'One'},{url:'https://example.test/two',title}]});
+ await assert.rejects(run(changed,{action:'index',index:0,getSnapshot,historyBinding:JSON.stringify(getSnapshot()),allowed:()=>{title='Replaced';return true;}}),/snapshot changed/);assert.equal(changed.calls,0);assert.equal(changed.eventNames().length,0);
+});
+test('indexed current-entry selection is a guarded no-op and raw indexes lack a snapshot authority',async()=>{
+ const c=fixture(),snapshot=()=>({activeIndex:c.index,entries:[{url:'https://example.test/one',title:'One'},{url:'https://example.test/two',title:'Two'}]});assert.equal((await run(c,{action:'index',index:1,getSnapshot:snapshot,historyBinding:JSON.stringify(snapshot())})).completed,true);assert.equal(c.calls,0);
+ for(const extra of [{index:-1},{index:0},{index:0,getSnapshot:snapshot},{index:0,getSnapshot:snapshot,historyBinding:'{}'}])await assert.rejects(run(c,{action:'index',...extra}));assert.equal(c.calls,0);
+});