perf(canvas): reuse immutable recovery encoding subtrees

src/lib/canvas-runtime/recovery-encoding.ts

@@ -0,0 +1,59 @@
+import type { Json } from '../canvas-core/types.ts';
+import { fault, freeze, validJson } from '../canvas-core/values.ts';
+import type { RecoveryImage } from './storage.ts';
+
+type Encoded = {value:Json|undefined;height:number;reusable:boolean};
+const immutable=new WeakMap<object,Encoded>(),sealed=new WeakSet<object>();
+
+/** JSON value semantics, with reuse only for transitively frozen plain data properties. */
+export function encodeRecoveryValue(input:unknown):Json {
+  const visiting=new Set<object>();
+  function visit(value:unknown,depth:number,key:string):Encoded {
+    if(value===null||typeof value==='string'||typeof value==='boolean'){if(depth>64)throw fault('invalid_recovery_payload');return{value,height:0,reusable:true};}
+    if(typeof value==='number'){if(depth>64)throw fault('invalid_recovery_payload');return{value:Number.isFinite(value)?(Object.is(value,-0)?0:value):null,height:0,reusable:true};}
+    if(value===undefined||typeof value==='symbol')return{value:undefined,height:0,reusable:true};
+    const fallback=()=>{
+      // Preserve the previous JSON codec for toJSON, boxed values and custom prototypes.
+      // These can depend on hidden mutable state and are deliberately never cached.
+      const text=JSON.stringify({[key]:value}),encoded=JSON.parse(text)[key] as Json|undefined;
+      if(encoded!==undefined&&!validJson(encoded,depth))throw fault('invalid_recovery_payload');
+      return{value:freeze(encoded),height:0,reusable:false};
+    };
+    if(typeof value==='bigint'||typeof value==='function')return fallback();
+    if(typeof value!=='object')throw fault('invalid_recovery_payload');
+    const object=value as object,cached=immutable.get(object);
+    if(cached){if(depth+cached.height>64)throw fault('invalid_recovery_payload');return cached;}
+    const prototype=Object.getPrototypeOf(object);
+    // A callable toJSON getter must also be evaluated afresh on every encode.
+    if(typeof (object as {toJSON?:unknown}).toJSON==='function'||(Array.isArray(object)?prototype!==Array.prototype&&prototype!==null:prototype!==Object.prototype&&prototype!==null))return fallback();
+    if(depth>64)throw fault('invalid_recovery_payload');
+    if(visiting.has(object))throw fault('invalid_recovery_payload');visiting.add(object);
+    const toJSON=Object.getOwnPropertyDescriptor(object,'toJSON');
+    let reusable=Object.isFrozen(object)&&(!toJSON||Object.hasOwn(toJSON,'value')),height=0;
+    try {
+      if(Array.isArray(object)){
+        const result:Json[]=[];
+        for(let index=0;index<object.length;index++){
+          const descriptor=Object.getOwnPropertyDescriptor(object,String(index));if(!descriptor||!Object.hasOwn(descriptor,'value'))reusable=false;
+          const child=visit(object[index],depth+1,String(index));if(child.value===undefined&&depth+1>64)throw fault('invalid_recovery_payload');result.push(child.value??null);height=Math.max(height,1+child.height);reusable&&=child.reusable;
+        }
+        const encoded={value:Object.freeze(result) as unknown as Json,height,reusable};if(reusable)immutable.set(object,encoded);return encoded;
+      }
+      const result:Record<string,Json>={};
+      for(const name of Object.keys(object)){
+        const descriptor=Object.getOwnPropertyDescriptor(object,name);if(!descriptor||!Object.hasOwn(descriptor,'value'))reusable=false;
+        const child=visit((object as Record<string,unknown>)[name],depth+1,name);reusable&&=child.reusable;
+        if(child.value!==undefined){Object.defineProperty(result,name,{value:child.value,enumerable:true});height=Math.max(height,1+child.height);}
+      }
+      const encoded={value:Object.freeze(result) as Json,height,reusable};if(reusable)immutable.set(object,encoded);return encoded;
+    }finally{visiting.delete(object);}
+  }
+  const result=visit(input,0,'');if(result.value===undefined)throw fault('invalid_recovery_payload');return result.value;
+}
+
+/** Only codec-owned, validated immutable images qualify for the storage copy fast path. */
+export function sealRecoveryImage(formatVersion:1|2,rootRevision:number,localRevision:number,payload:unknown):RecoveryImage {
+  if(![1,2].includes(formatVersion)||!Number.isSafeInteger(rootRevision)||rootRevision<0||!Number.isSafeInteger(localRevision)||localRevision<0||localRevision>rootRevision)throw fault('corrupt_recovery_image');
+  const image=Object.freeze({formatVersion,rootRevision,localRevision,payload:encodeRecoveryValue(payload)});sealed.add(image);return image;
+}
+export function isSealedRecoveryImage(image:RecoveryImage):boolean{return sealed.has(image);}

src/lib/canvas-runtime/recovery.ts

@@ -1,3 +1,4 @@
+import { sealRecoveryImage } from './recovery-encoding.ts';
 import { validateImportJob, type ImportJob } from './imports.ts';
 import { validateElisions, withLocalLifecycles } from './elision.ts';
 import type { Change, CoreSnapshot, Document, HistoryEntry, HistoryState, Id, Json, OperationIntent, Registry } from '../canvas-core/types.ts';
@@ -15,14 +16,13 @@ import type { RecoveryImage } from './storage.ts';
 const documentValue = (document: Document) => ({ projectId: document.projectId, canvases: [...document.canvases.values()], elements: [...document.elements.values()], tombstones: [...document.tombstones] });
 /** Plain records only: functions, credentials, renderer objects, URLs and Map methods never serialize. */
 export function encodeRecovery(snapshot: EngineSnapshot): RecoveryImage {
-  const payload = JSON.parse(JSON.stringify({
+  const payload = {
     document: documentValue(snapshot.document),
     history: { undo: snapshot.history.undo, redo: snapshot.history.redo, entries: [...snapshot.history.entries] },
     operations: [...snapshot.operations],
     runtime: { imports:[...(snapshot.runtime.imports??[])], recoveries:[...(snapshot.runtime.recoveries??[])], runs: [...snapshot.runtime.runs], resources: [...snapshot.runtime.resources], resourcePins: [...snapshot.runtime.resourcePins], acknowledged: documentValue(snapshot.runtime.acknowledged), versions: [...snapshot.runtime.versions], receipts: [...snapshot.runtime.receipts], conflicts: [...snapshot.runtime.conflicts], ledger: { ...snapshot.runtime.ledger, operations: [...snapshot.runtime.ledger.operations], requests: [...snapshot.runtime.ledger.requests] } },
-  })) as Json;
-  if (!validJson(payload)) throw fault('invalid_recovery_payload');
-  return freeze({ formatVersion: snapshot.runtime.imports?.size ? 2 : 1, rootRevision: snapshot.rootRevision, localRevision: snapshot.revision, payload });
+  };
+  return sealRecoveryImage(snapshot.runtime.imports?.size ? 2 : 1,snapshot.rootRevision,snapshot.revision,payload);
 }
 type ObjectValue = Record<string, unknown>;
 function object(value: unknown): ObjectValue { if (!value || Array.isArray(value) || typeof value !== 'object') throw fault('corrupt_recovery_image'); return value as ObjectValue; }

src/lib/canvas-runtime/storage.ts

@@ -1,3 +1,4 @@
+import { isSealedRecoveryImage } from './recovery-encoding.ts';
 import type { Json } from '../canvas-core/types.ts';
 import { clone, equal, fault, validJson } from '../canvas-core/values.ts';
 
@@ -117,7 +118,7 @@ export function createBrowserStorage(options: { indexedDB?: IDBFactory; locks?:
     },
     async commit(leader: StorageLeader, batch: DurableBatch) {
       // Copy before awaiting: callers cannot change the durable cut while a transaction queues.
-      const image = clone(batch.image), files = [...(batch.files ?? [])]; validateImage(image);
+      const image = isSealedRecoveryImage(batch.image) ? batch.image : clone(batch.image), files = (batch.files ?? []).map(file => ({id:file.id,bytes:file.bytes})); if(!isSealedRecoveryImage(image))validateImage(image);
       const stored: StoredImage = { image, checksum: await checksum(image) };
       return execute(leader, ['checkpoints', 'journal', 'files'], 'readwrite', async (transaction, metadata, key) => {
         const previous = metadata.throughRevision;

tests/headless/browser-storage-cases.mjs

@@ -1,3 +1,4 @@
+import {sealRecoveryImage} from '../../src/lib/canvas-runtime/recovery-encoding.ts';
 import {planDuplicateAsync} from '../../src/lib/canvas-runtime/duplicate.ts';
 import {replayHistoryEvidence,sameHistory} from '../../src/lib/canvas-runtime/history-replay.ts';
 import { createBrowserStorage } from '../../src/lib/canvas-runtime/storage.ts';
@@ -7,6 +8,17 @@ import { createFoundryRuns } from '../../src/lib/canvas-service/runs.ts';
 import { createFoundryAssets } from '../../src/lib/canvas-service/assets.ts';
 import { createFoundryPersistence } from '../../src/lib/canvas-service/foundry.ts';
 
+async function ownedImageStorageCase(name,assert){
+  const storage=createBrowserStorage({name:`${name}-owned-image`}),scope={accountId:'owner',workspaceId:'workspace',projectId:'project'};let leader;
+  try{
+    leader=await storage.claim(scope);const payload={nested:{title:'captured'}},descriptor={id:'captured-file',bytes:new Blob(['captured bytes'])},raw={formatVersion:1,rootRevision:0,localRevision:0,payload};
+    const first=storage.commit(leader,{image:raw,files:[descriptor]});payload.nested.title='changed';descriptor.id='changed-file';descriptor.bytes=new Blob(['changed bytes']);await first;
+    assert((await storage.recover(leader)).payload.nested.title==='captured','unowned image changed while checksum was pending');assert(await(await storage.readFile(leader,'captured-file')).text()==='captured bytes','file descriptor changed while checksum was pending');assert(await storage.readFile(leader,'changed-file')===undefined,'late descriptor identity leaked into storage');
+    const sealed=sealRecoveryImage(1,1,1,{nested:{title:'sealed'}});await storage.commit(leader,{image:sealed});assert((await storage.recover(leader)).payload.nested.title==='sealed','sealed image did not survive IndexedDB/checksum');
+    const nested={title:'before'},impostor=Object.freeze({formatVersion:1,rootRevision:2,localRevision:1,payload:{nested}}),pending=storage.commit(leader,{image:impostor});nested.title='after';await pending;assert((await storage.recover(leader)).payload.nested.title==='before','a shallow-frozen impostor bypassed the defensive copy');
+  }finally{await leader?.release();storage.close();indexedDB.deleteDatabase(`${name}-owned-image`);}
+}
+
 async function cooperativeCopyCase(assert) {
   const registry=createRegistry(builtinComponents()),source=createDocument('copy-project',[{id:'copy-root',parent:null}],Array.from({length:1500},(_,index)=>({id:`source-${index}`,incarnation:1,structure:'node',ownerCanvasId:'copy-root',componentId:'text',dataVersion:1,data:{title:`item ${index}`,text:''},geometry:{x:index,y:0,width:100,height:100,rotation:0}})));
   let next=0,timerRan=false;
@@ -513,6 +525,8 @@ export async function run() {
     results.push('project engine reopens real IndexedDB with one history unit and the original request; ACK resolves without duplicate edit');
     await resourceRecoveryCase(name, assert);
     results.push('staged file and image recover from real IndexedDB; lost upload ACK queries stable resource identity');
+    await ownedImageStorageCase(name,assert);
+    results.push('owned immutable recovery images survive IndexedDB checksums; mutable images and file descriptors are captured before asynchronous work');
     await cooperativeCopyCase(assert);
     results.push('cooperative duplicate planning yields to actual browser tasks and cancellation without mutating the source');
     await duplicateRecoveryCase(name,assert);

tests/headless/recovery-encoding.test.mjs

@@ -0,0 +1,28 @@
+import {test} from 'node:test';
+import assert from 'node:assert/strict';
+import {freeze,validJson} from '../../src/lib/canvas-core/values.ts';
+import {encodeRecoveryValue,sealRecoveryImage,isSealedRecoveryImage} from '../../src/lib/canvas-runtime/recovery-encoding.ts';
+const json=value=>JSON.parse(JSON.stringify(value));
+
+test('recovery encoding preserves JSON value semantics including omitted, sparse, special-key and custom values',()=>{
+ const value={number:-0,infinite:Infinity,missing:undefined,symbol:Symbol('s'),fn(){},array:[,undefined,()=>{},Symbol('s'),NaN],date:new Date('2026-01-01T00:00:00Z'),boxed:new Number(4),custom:{toJSON(key){return{key,text:'custom'};}},['__proto__']:{safe:true}};
+ const encoded=encodeRecoveryValue(value);assert.deepEqual(encoded,json(value));assert.equal(validJson(encoded),true);assert.equal(Object.getPrototypeOf(encoded),Object.prototype);assert.equal(Object.hasOwn(encoded,'__proto__'),true);assert.ok(Object.isFrozen(encoded.array));
+});
+test('only frozen data subtrees are reused and the encoded image is detached and immutable',()=>{
+ const shared=freeze({items:[{title:'stable',unknown:{retained:true}}]}),left=encodeRecoveryValue({shared}),right=encodeRecoveryValue({shared});assert.equal(left.shared,right.shared);assert.notEqual(left.shared,shared);assert.throws(()=>{left.shared.items[0].title='changed';},TypeError);
+ const mutable={title:'before'},shallow=Object.freeze({mutable});assert.equal(encodeRecoveryValue(shallow).mutable.title,'before');mutable.title='after';assert.equal(encodeRecoveryValue(shallow).mutable.title,'after');assert.equal(encodeRecoveryValue(shallow).mutable===mutable,false);
+});
+test('frozen getters, custom prototypes and internally mutable objects are evaluated again',()=>{
+ let current='first';const getter=Object.freeze({get title(){return current;}});assert.equal(encodeRecoveryValue(getter).title,'first');current='second';assert.equal(encodeRecoveryValue(getter).title,'second');
+ let enabled=false;const dynamic={value:'ordinary'};Object.defineProperty(dynamic,'toJSON',{get(){return enabled?()=>({changed:true}):undefined;}});Object.freeze(dynamic);assert.deepEqual(encodeRecoveryValue(dynamic),{value:'ordinary'});enabled=true;assert.deepEqual(encodeRecoveryValue(dynamic),{changed:true});
+ const date=Object.freeze(new Date('2026-01-01Z'));const parent=Object.freeze({date});assert.deepEqual(encodeRecoveryValue(parent),json(parent));date.setUTCFullYear(2027);assert.deepEqual(encodeRecoveryValue(parent),json(parent));
+ const prototype=Object.create(Array.prototype);prototype[0]='old';const array=new Array(1);Object.setPrototypeOf(array,prototype);Object.freeze(array);assert.deepEqual(encodeRecoveryValue(array),['old']);prototype[0]='new';assert.deepEqual(encodeRecoveryValue(array),['new']);
+});
+test('cached subtree height cannot bypass the depth bound and omitted object fields do not count',()=>{
+ const nest=(count,leaf)=>{for(let i=0;i<count;i++)leaf=Object.freeze({child:leaf});return leaf;},leaf=freeze({value:1});encodeRecoveryValue(leaf);assert.equal(validJson(encodeRecoveryValue(nest(63,leaf))),true);assert.throws(()=>encodeRecoveryValue(nest(64,leaf)),/invalid_recovery_payload/);
+ assert.equal(validJson(encodeRecoveryValue(nest(64,Object.freeze({optional:undefined})))),true);assert.throws(()=>encodeRecoveryValue(nest(64,Object.freeze([undefined]))),/invalid_recovery_payload/);
+ const cycle={};cycle.self=cycle;assert.throws(()=>encodeRecoveryValue(cycle),/invalid_recovery_payload/);assert.throws(()=>encodeRecoveryValue({big:1n}));
+});
+test('only factory-owned images are recognized; immutable-looking impostors retain defensive-copy handling',()=>{
+ const mutable={title:'before'},image=sealRecoveryImage(2,3,2,{mutable});assert.equal(isSealedRecoveryImage(image),true);assert.equal(isSealedRecoveryImage(structuredClone(image)),false);assert.equal(isSealedRecoveryImage(Object.freeze({...image})),false);mutable.title='after';assert.equal(image.payload.mutable.title,'before');assert.ok(Object.isFrozen(image.payload.mutable));assert.throws(()=>sealRecoveryImage(2,1,2,{}),/corrupt_recovery_image/);assert.throws(()=>sealRecoveryImage(3,1,1,{}),/corrupt_recovery_image/);
+});