fix(canvas): let headless hosts configure asset display routes

tests/headless/foundry.integration.mjs

@@ -15,7 +15,8 @@ const {FOUNDRY_HTTP_URL:url,FOUNDRY_TEST_PROJECT:project,FOUNDRY_TEST_ACCOUNT:ac
 assert.ok(url&&project&&accountId&&workspaceId&&rootId&&token,'requires isolated Foundry HTTP fixture');
 const registry=createRegistry(builtinComponents()),basePath=`${url}/projects/${project}/`,calls=[];
 let loseNextAck=false,loseNextAssetAck=false,loseNextAIAdmission=false,loseNextAIAction=false;
-const rawTransport=createFoundryTransport({basePath,accountId,isCurrentIdentity:()=>true,fetch:async(resource,init)=>{const headers=new Headers(init.headers);headers.set('Authorization',`Bearer ${token}`);return fetch(resource,{...init,headers});}});
+const authenticatedFetch=async(resource,init={})=>{assert.equal(new URL(resource).origin,new URL(url).origin);const headers=new Headers(init.headers);headers.set('Authorization',`Bearer ${token}`);headers.set('X-Expected-Account',accountId);return fetch(resource,{...init,headers});};
+const rawTransport=createFoundryTransport({basePath,accountId,isCurrentIdentity:()=>true,fetch:authenticatedFetch});
 const transport=async input=>{const call={method:input.method,path:input.path,requestId:input.requestId,body:input.body};calls.push(call);const result=await rawTransport(input);if(input.path.includes('/canvas/ai/'))call.response={httpStatus:result.status,...Object.fromEntries(['protocol_version','request_id','operation_id','action','admission','status','error'].filter(key=>result.body?.[key]!==undefined).map(key=>[key,result.body[key]]))};if(loseNextAIAdmission&&input.method==='POST'&&input.path.endsWith('/ai/runs')&&result.status===202){loseNextAIAdmission=false;throw Error('injected response loss after AI admission');}if(loseNextAIAction&&input.method==='POST'&&/\/(cancel|apply)$/.test(input.path)&&result.status===200){loseNextAIAction=false;throw Error('injected response loss after AI action');}if(loseNextAssetAck&&input.method==='POST'&&input.path.endsWith('/assets')&&result.status>=200&&result.status<300){loseNextAssetAck=false;throw Error('injected upload response loss');}if(loseNextAck&&input.method==='POST'&&result.status===200){loseNextAck=false;throw Error('injected response loss after server commit');}return result;};
 const path=`workspaces/${workspaceId}/materials/${rootId}/canvas`;
 const migration=await loadFoundryModel(transport,workspaceId,rootId,registry);assert.equal(migration.status,'migration-required');
@@ -30,7 +31,7 @@ const share=batch=>{for(const write of batch.depot?.writes??[]){const key=JSON.s
 const storage={assetDepot:depotPort,async claim(){assert.equal(owner,undefined);const held={scope,fence:1,active:true,async release(){held.active=false;owner=undefined;}};owner=held;return held;},async recover(){return structuredClone(image);},async commit(held,batch){assert.strictEqual(held,owner);const next=structuredClone(batch.image);for(const file of batch.files??[])files.set(file.id,file.bytes);for(const id of batch.deleteFiles??[])files.delete(id);image=next;share(batch);return{durableRootRevision:next.rootRevision};},async readFile(_held,id){return files.get(id);},close(){}};
 let nextTimer=0;const timers=new Map();
 const tick=()=>{const ready=[...timers].filter(([,timer])=>timer.due<=now).sort((a,b)=>a[1].due-b[1].due||a[0]-b[0]);let fired=0;for(const[id,timer]of ready)if(timers.delete(id)){fired++;timer.callback();}return fired;};
-const persistence=createFoundryPersistence({registry,workspaceId,rootId,transport}),assets=createFoundryAssets({workspaceId,project,origin:'https://api.example.com',transport}),clock={now:()=>now,setTimer(callback,delay){const id=++nextTimer;timers.set(id,{callback,due:now+delay});return id;},clearTimer(id){timers.delete(id);}};
+const persistence=createFoundryPersistence({registry,workspaceId,rootId,transport}),assets=createFoundryAssets({workspaceId,project,origin:'https://api.example.com',transport,displayURL:id=>`${basePath}workspaces/${workspaceId}/assets/${encodeURIComponent(id)}?variant=preview`}),clock={now:()=>now,setTimer(callback,delay){const id=++nextTimer;timers.set(id,{callback,due:now+delay});return id;},clearTimer(id){timers.delete(id);}};
 const open=(extra={})=>openProjectEngine({scope,registry,storage,persistence,assets,document:initial.document,versions:initial.versions,clock,createId:randomUUID,onError:error=>errors.push(error),...extra});
 const node=(id,ownerCanvasId=rootId)=>({id,incarnation:1,ownerCanvasId,componentId:'text',dataVersion:1,structure:'node',data:{title:id,text:''},geometry:{x:0,y:0,width:100,height:80,rotation:0}});
 let engine=await open();
@@ -86,7 +87,7 @@ try{
  engine=await openProjectEngine(targetOptions);const adoptedId=randomUUID();assert.equal((await engine.adoptResource(imageResource.id,(handle,tx)=>tx.dispatch({type:'element.create',element:{...node(adoptedId,targetRoot),componentId:'image',data:{title:'Adopted existing image',text:'',assetId:handle.id,src:handle.src}}}))).status,'applied');await engine.settle();assert.equal(targetImage.formatVersion,13);assert.equal((await loadFoundryModel(transport,workspaceId,targetRoot,registry)).document.elements.get(adoptedId).data.assetId,imageResource.id);assert.equal(calls.filter(call=>call.method==='POST'&&call.path.endsWith('/assets')).length,uploadCount);
  await engine.close();engine=await openProjectEngine(targetOptions);const display=await engine.displayResource(imageResource.id);assert.ok(display.url.startsWith('blob:'));assert.deepEqual(Buffer.from(await(await fetch(display.url)).arrayBuffer()),Buffer.from(await originalBytes.arrayBuffer()));display.release();assert.equal(engine.editor.history.undo().status,'applied');await engine.settle();assert.equal(engine.editor.history.redo().status,'applied');await engine.settle();assert.equal((await loadFoundryModel(transport,workspaceId,targetRoot,registry)).document.elements.get(adoptedId).incarnation,2);assert.equal(calls.filter(call=>call.method==='POST'&&call.path.endsWith('/assets')).length,uploadCount);
  let aiReport={};if(process.env.FOUNDRY_TEST_AI_WORKER==='1'){
-  await engine.close();aiReport=await verifyFoundryAI({open:()=>openProjectEngine({...targetOptions,runs:createFoundryRuns({workspaceId,rootId:targetRoot,registry,transport})}),transport,rootId:targetRoot,imageId:adoptedId,assets,calls,tick,advance:()=>{now+=10_000;},loseAdmission:()=>{loseNextAIAdmission=true;},loseAction:()=>{loseNextAIAction=true;}});
+  await engine.close();aiReport=await verifyFoundryAI({open:()=>openProjectEngine({...targetOptions,runs:createFoundryRuns({workspaceId,rootId:targetRoot,registry,transport})}),transport,rootId:targetRoot,imageId:adoptedId,assets,calls,tick,readDisplay:async url=>{const response=await authenticatedFetch(url);assert.equal(response.status,200);return Buffer.from(await response.arrayBuffer());},advance:()=>{now+=10_000;},loseAdmission:()=>{loseNextAIAdmission=true;},loseAction:()=>{loseNextAIAction=true;}});
  }
  assert.ok(errors.every(error=>String(error).includes('injected response loss')),'unexpected engine error: '+errors.map(String).join(','));
  console.log(JSON.stringify({status:'ok',...aiReport,migrationRetry:true,realHttp:true,lostAckRecovered:true,atomicPartition:true,deepCopyUpperEdge:true,nativePartialReport:true,loadingImportOldCapture:true,unloadedTailDuringCopy:true,scopedImageLostAck:true,copiedPendingImageSharesUpload:true,authorizedAssetMetadata:true,originalAssetBytes:true,crossProjectAdoption:true,adoptionReopenedBytes:true,requests:calls.length}));