Resume durable copy preparation from saved planning cursors

src/lib/canvas-runtime/duplicate.ts

@@ -1,3 +1,4 @@
+import { createDuplicatePlanner, type DuplicateCheckpoint } from '../canvas-core/duplicate-checkpoint.ts';
 import type { Document, Registry, Target } from '../canvas-core/types.ts';
 import { planDuplicateSteps, type DuplicateOptions, type DuplicatePlan } from '../canvas-core/duplicate.ts';
 import { clone, fault, freeze } from '../canvas-core/values.ts';
@@ -45,3 +46,16 @@ export async function planDuplicateAsync(document: Document, registry: Registry,
     steps.return(undefined as never);
   }
 }
+
+/** Resume semantic planning cursors. Source/output validation and derived output caches are rebuilt. */
+export async function planDuplicateResumable(document:Document,registry:Registry,selection:readonly Target[],options:DuplicateOptions,binding:{sourceToken:string;schemaToken:string;checkpoint?:DuplicateCheckpoint},scheduling:Omit<DuplicateScheduling,'checkpoint'>&{checkpoint?:(state:DuplicateCheckpoint)=>Promise<void>}={}):Promise<DuplicatePlan>{
+  const budget=scheduling.frameBudgetMs??6,limit=scheduling.maxStepsPerSlice??512,now=scheduling.now??(()=>performance.now()),yieldTask=scheduling.yieldTask??(()=>new Promise<void>(resolve=>setTimeout(resolve,0)));
+  if(!Number.isFinite(budget)||budget<=0||!Number.isSafeInteger(limit)||limit<1)throw fault('invalid_copy_budget');
+  const check=()=>{if(scheduling.signal?.aborted)throw fault('copy_aborted');};check();
+  const settings=Object.freeze({createId:options.createId,...(options.worldOffset?{worldOffset:freeze(clone(options.worldOffset))}:{}),...(options.mapping?{mapping:freeze(clone(options.mapping))}:{})}),planner=createDuplicatePlanner(document,registry,freeze(clone(selection)),settings,binding);
+  while(true){
+    const start=now();let count=0;
+    do{check();const done=planner.step();check();if(done)return planner.result();count++;}while(count<limit&&now()-start<budget);
+    if(scheduling.checkpoint)await scheduling.checkpoint(planner.checkpoint());check();await yieldTask();
+  }
+}