/**
 * 用户审阅冲突后按新基线重新规划原意图的纯工具，不是正常 ACK 路径的自动覆盖合并。
 * 保留用户实际修改的字段/世界几何意图，未修改的当前字段继续沿用 fresh 数据；未知类型或
 * 生命周期/坐标上下文无法确认时拒绝。生成的是新 changes，原冻结 body/key 不在此改写。
 */
import type { Change, Document, ElementRecord, FieldChange, Id, Json, OperationIntent, Registry } from '../canvas-core/types.ts';
import { applyChanges, commonCanvas, validateDocument } from '../canvas-core/document.ts';
import { canvasTransform, convertGeometry, convertPath, type Transform } from '../canvas-core/coordinates.ts';
import { closeNumber, closeScale, presentationRecord, unitScale, withUnitScale } from '../canvas-core/units.ts';
import { removalChanges, repairConnectionOwners } from '../canvas-core/structure.ts';
import { equal, fault, freeze, readMap } from '../canvas-core/values.ts';

/** 原操作相关对象的前后记录及 owner 变换；用于区分用户意图与仅由坐标转换引起的差异。 */
export type IntentContext = { readonly before:ReadonlyMap<Id,ElementRecord>; readonly after:ReadonlyMap<Id,ElementRecord>; readonly transforms:ReadonlyMap<Id,Transform>; readonly beforeTransforms:ReadonlyMap<Id,Transform> };
/** Reconstruct only immutable intention metadata. This mutable cursor is never published as a document. */
/** 从已包含这些意图效果的 working 逆序退回，重建局部前后记录及 owner 变换。
 * 输入顺序就是应用顺序；函数不按 sequence 排序，也不验证当前文档确由这些意图产生。
 * 这里只还原意图元数据，不按 before/after 条件执行撤销，不回退墓碑、不分配新代次或发布文档。
 * 只读 Map 捕获表成员，记录值沿用不可变输入；不是任意外部对象的深克隆边界。 */
export function intentContexts(document:Document,intents:readonly OperationIntent[]):ReadonlyMap<Id,IntentContext> {
  const elements=new Map(document.elements),canvases=new Map(document.canvases),contexts=new Map<Id,IntentContext>();
  const cursor={...document,elements,canvases};
  for(const intent of [...intents].reverse()){
    // 收集自身、连线端点与 canvas 入口，捕获足够的身份和坐标上下文，不复制全项目到每条意图。
    const ids=new Set<Id>(),owners=new Set<Id>();
    for(const change of intent.changes){
      if(change.kind==='field'){ids.add(change.target.id);if(change.field==='source'||change.field==='target')for(const endpoint of [change.before,change.after])if(endpoint&&typeof endpoint==='object'&&!Array.isArray(endpoint)&&typeof endpoint.elementId==='string')ids.add(endpoint.elementId);}
      else if(change.kind==='element'){ids.add(change.id);for(const record of [change.before,change.after])if(record?.structure==='connection'){ids.add(record.source.elementId);ids.add(record.target.elementId);}}
      else for(const record of [change.before,change.after])if(record?.parent)ids.add(record.parent.entryElementId);
    }
    const after=new Map<Id,ElementRecord>();for(const id of ids){const record=elements.get(id);if(record){after.set(id,record);owners.add(record.ownerCanvasId);}}
    const transforms=new Map<Id,Transform>();for(const owner of owners)if(canvases.has(owner))transforms.set(owner,canvasTransform(cursor,owner));
    // 直接把记录/字段写回原 before，不检查当前是否等于 after；field 缺对象/代次不符时跳过。
    // cursor 中间树可不完整，随后仅在 owner 仍存在时取变换；无法解析的祖先链仍可能抛错。
    for(const change of [...intent.changes].reverse()){
      if(change.kind==='element'){if(change.before)elements.set(change.id,change.before);else elements.delete(change.id);}
      else if(change.kind==='canvas'){if(change.before)canvases.set(change.id,change.before);else canvases.delete(change.id);}
      else {const current=elements.get(change.target.id);if(!current||current.incarnation!==change.target.incarnation)continue;
        if(change.field.startsWith('data.')){const key=change.field.slice(5),data={...current.data};if(change.beforePresent===false)delete data[key];else data[key]=change.before;elements.set(current.id,freeze({...current,data}));}
        else elements.set(current.id,freeze({...current,[change.field]:change.before}) as ElementRecord);
      }
    }
    const before=new Map([...ids].flatMap(id=>elements.has(id)?[[id,elements.get(id)!] as const]:[])),beforeTransforms=new Map<Id,Transform>();for(const record of before.values())if(canvases.has(record.ownerCanvasId)&&!beforeTransforms.has(record.ownerCanvasId))beforeTransforms.set(record.ownerCanvasId,canvasTransform(cursor,record.ownerCanvasId));
    contexts.set(intent.id,Object.freeze({before:readMap(before),after:readMap(after),transforms:readMap(transforms),beforeTransforms:readMap(beforeTransforms)}));
  }
  return readMap(contexts);
}

/** 比较路径是否仅存在坐标换算误差：点坐标用容差，其它字段与 knot 顺序仍严格比较。 */
function sameConvertedPath(left:Json,right:Json):boolean {
  if(equal(left,right))return true;
  if(!left||!right||typeof left!=='object'||typeof right!=='object'||Array.isArray(left)||Array.isArray(right)||!Array.isArray(left.knots)||!Array.isArray(right.knots))return false;
  const {knots:a,startControl:as,endControl:ae,...ar}=left,{knots:b,startControl:bs,endControl:be,...br}=right;
  /** 控制点容差比较同时保留扩展字段检查，不能把两条实际不同的曲线误认为坐标等效。 */
  const point=(a:Json|undefined,b:Json|undefined)=>{if(a===undefined||b===undefined)return a===b;if(!a||!b||typeof a!=='object'||typeof b!=='object'||Array.isArray(a)||Array.isArray(b))return false;const{x:ax,y:ay,...restA}=a,{x:bx,y:by,...restB}=b;return typeof ax==='number'&&typeof ay==='number'&&typeof bx==='number'&&typeof by==='number'&&closeNumber(ax,bx)&&closeNumber(ay,by)&&equal(restA,restB);};
  return equal(ar,br)&&point(as,bs)&&point(ae,be)&&a.length===b.length&&a.every((value,index)=>{const other=b[index];if(!value||!other||typeof value!=='object'||typeof other!=='object'||Array.isArray(value)||Array.isArray(other))return false;const{position:p,in:i,out:o,...rest}=value,{position:q,in:j,out:k,...remaining}=other;return equal(rest,remaining)&&point(p,q)&&point(i,j)&&point(o,k);});
}
/** 以键的存在性和值比较找 presentation 顶层差异，再覆盖/删除 current 的对应键。
 * 嵌套键值作为整体处理，不递归合并；unitScale 排除在本函数外，交几何分支做视觉单位换算。
 * 无变化时沿用 current；有变化后若结果无键则返回 undefined，交调用方处理字段存在性。 */
function presentationDelta(current:Json|undefined,before:Json|undefined,after:Json|undefined):Json|undefined {
  if(equal(before,after))return current;
  const start=presentationRecord(before),end=presentationRecord(after),keys=new Set([...Object.keys(start),...Object.keys(end)]);keys.delete('unitScale');
  const changed=[...keys].filter(key=>Object.hasOwn(start,key)!==Object.hasOwn(end,key)||!equal(start[key],end[key]));if(!changed.length)return current;
  const result=new Map(Object.entries(presentationRecord(current)));for(const key of changed){if(Object.hasOwn(end,key))result.set(key,end[key]);else result.delete(key);}
  return result.size?Object.fromEntries(result):undefined;
}
/** 重挂节点时先将原前/后几何与当前几何转换到世界空间，保留未修改维度的当前值。
 * 用户明确改变的中心/尺寸/旋转取其意图值，再转到 fresh destination；不是盲加一份旧 local patch。 */
function movedNode(current:Extract<ElementRecord,{structure:'node'}>,originalBefore:Extract<ElementRecord,{structure:'node'}>,originalAfter:Extract<ElementRecord,{structure:'node'}>,beforeBasis:Transform,afterBasis:Transform,source:Transform,destination:Transform,intent:OperationIntent){
  const world:Transform={x:0,y:0,scale:1,rotation:0},start=convertGeometry(originalBefore.geometry,beforeBasis,world),end=convertGeometry(originalAfter.geometry,afterBasis,world),fresh=convertGeometry(current.geometry,source,world);
  // 世界中心用于分别判断横/纵移动意图；未变化的维度取 fresh，修改维度取原意图终值，而非叠加 delta。
  const center=(g:typeof start)=>({x:g.x+g.width/2,y:g.y+g.height/2}),a=center(start),b=center(end),c=center(fresh),width=closeNumber(start.width,end.width)?fresh.width:end.width,height=closeNumber(start.height,end.height)?fresh.height:end.height;
  const x=closeNumber(a.x,b.x)?c.x:b.x,y=closeNumber(a.y,b.y)?c.y:b.y,rotation=Math.abs(((start.rotation-end.rotation+540)%360)-180)<1e-9?fresh.rotation:end.rotation;
  const geometry=convertGeometry({x:x-width/2,y:y-height/2,width,height,rotation},world,destination);
  // 只有原意图显式改变视觉 unitScale 才采用目标视觉尺度；纯换 owner 保留当前外观。
  const unitEdited=intent.changes.some(change=>change.kind==='field'&&change.target.id===current.id&&change.field==='data.presentation'&&!closeScale(unitScale(change.before),unitScale(change.after)));
  const oldStyle=unitScale(originalBefore.data.presentation)*beforeBasis.scale,newStyle=unitScale(originalAfter.data.presentation)*afterBasis.scale;
  const desiredStyle=unitEdited&&!closeScale(oldStyle,newStyle)?newStyle:unitScale(current.data.presentation)*source.scale;
  const presentation=withUnitScale(presentationDelta(current.data.presentation,originalBefore.data.presentation,originalAfter.data.presentation),desiredStyle/destination.scale);
  return{geometry,presentation};
}

/** Restore batches may have inverse storage order (canvas before entry). Only reorder adjacent creates, never move across an edit/delete. */
/** 只在连续创建段内按 parent/entry/owner/端点依赖拓扑排序，绝不跨编辑/删除重排。
 * 仅段内依赖参与 Kahn 计数；段外依赖是否存在留给执行/最终校验。元素与 canvas 分命名空间。
 * ready 按发现顺序排队，不保证每次都选择剩余项中原索引最小者；重 ID 或环直接拒绝。 */
function orderedCreates(changes:readonly Change[]):readonly Change[]{
  const result:Change[]=[];
  /** before=null 且 after 存在才是创建，整记录替换不能冒充依赖排序候选。 */
  const creating=(change:Change)=>change.kind!=='field'&&!change.before&&!!change.after;
  for(let offset=0;offset<changes.length;){
    if(!creating(changes[offset])){result.push(changes[offset++]);continue;}
    let end=offset;while(end<changes.length&&creating(changes[end]))end++;
    const batch=changes.slice(offset,end),keys=batch.map(change=>`${change.kind}:${(change as Extract<Change,{kind:'element'|'canvas'}>).id}`),positions=new Map(keys.map((key,index)=>[key,index]));
    if(positions.size!==batch.length)throw fault('recovery_creation_dependency_conflict');
    // Kahn 排序：counts 记段内依赖数，waiting 存反向边，ready 按原遇到顺序入列。
    const counts=batch.map(()=>0),waiting=new Map<number,number[]>(),ready:number[]=[];
    batch.forEach((change,index)=>{
      const dependencies=new Set<string>();
      if(change.kind==='canvas'&&change.after?.parent){dependencies.add(`canvas:${change.after.parent.canvasId}`);dependencies.add(`element:${change.after.parent.entryElementId}`);}
      if(change.kind==='element'&&change.after){dependencies.add(`canvas:${change.after.ownerCanvasId}`);if(change.after.structure==='connection'){dependencies.add(`element:${change.after.source.elementId}`);dependencies.add(`element:${change.after.target.elementId}`);}}
      for(const key of dependencies){const dependency=positions.get(key);if(dependency===undefined)continue;counts[index]++;const list=waiting.get(dependency)??[];list.push(index);waiting.set(dependency,list);}
      if(!counts[index])ready.push(index);
    });
    // 每输出一个创建就降低依赖项计数；输出不足整段说明依赖环/冲突，整体拒绝。
    let emitted=0;for(let next=0;next<ready.length;next++){const index=ready[next];result.push(batch[index]);emitted++;for(const dependent of waiting.get(index)??[])if(--counts[dependent]===0)ready.push(dependent);}
    if(emitted!==batch.length)throw fault('recovery_creation_dependency_conflict');offset=end;
  }
  return result;
}

/** Re-plan against current data; whole element replacement is unsupported. */
/** 在 fresh 私有候选上重新生成条件 changes，保留当前未被用户意图修改的数据，最终整图校验才返回。
 * 本函数不验证恢复选择/账本依赖，不发布 Root、不记录 history、不修改原冻结请求；这些由冲突协调器负责。
 * 整元素仅支持显式增删，canvas 记录可重建 parent；普通字段的 before 从 fresh 实值重新生成。
 * 输入应为已捕获的不可变模型/上下文，辅助 apply 的冻结不构成任意外部对象的深隔离保证。 */
export function rebaseIntent(document:Document,intent:OperationIntent,context:IntentContext,registry:Registry):{document:Document;changes:readonly Change[]} {
  // moved 标记需整体世界空间重规划的节点；deferredPaths 等端点/树最终确定后再算曲线。
  const before=document,changes:Change[]=[],moved=new Set<Id>(),deferredPaths:FieldChange[]=[];
  for(const change of intent.changes)if(change.kind==='field'&&change.field==='ownerCanvasId'&&context.after.get(change.target.id)?.structure==='node')moved.add(change.target.id);
  /** 每条新变化立即作用于私有 candidate，后面的条件读取已重规划后的实际 before。 */
  function apply(change:Change){document=applyChanges(document,[change]);changes.push(freeze(change));}
  /** 目标必须存在、代次相同且 registry 已知；上下文含 prior 时再比较结构/组件/版本。
   * 这是字段分支共用准入，具体能力检查在各分支；上下文缺 prior 不在这里补造类型依据。 */
  function target(change:FieldChange){const current=document.elements.get(change.target.id),prior=context.before.get(change.target.id)??context.after.get(change.target.id);if(!current||current.incarnation!==change.target.incarnation)throw fault('stale_incarnation',[change.target.id]);if(prior&&(current.componentId!==prior.componentId||current.dataVersion!==prior.dataVersion||current.structure!==prior.structure))throw fault('recovery_target_type_changed',[current.id]);if(registry.resolve(current)!=='known')throw fault('unsupported_component',[current.id]);return current;}
  /** 当前端点须为 node，且与 context.after 中对象代次一致；无上下文也拒绝。
   * 这里不单独比较端点的 componentId/dataVersion，图关系是否合法仍由最终校验判断。 */
  function endpoint(id:Id){const current=document.elements.get(id),expected=context.after.get(id);if(!current||current.structure!=='node'||!expected||current.incarnation!==expected.incarnation)throw fault('stale_endpoint',[id]);}
  // 按受限依赖顺序处理创建；删除/字段意图的原语义顺序仍保留。
  for(const original of orderedCreates(intent.changes)){
    if(original.kind==='element'){
      const current=document.elements.get(original.id);
      if(original.before===null&&original.after){
        // 仅 undo/redo 显式恢复允许 dead+1；其它碰撞不能静默改 ID 或复用墓碑。
        const dead=document.tombstones.get(original.id),restoring=['undo','redo'].includes(intent.origin)&&dead!==undefined&&original.after.incarnation===dead+1;
        if(current||dead!==undefined&&!restoring)throw fault('recovery_identity_collision',[original.id]);
        if(registry.resolve(original.after)!=='known')throw fault('unsupported_component',[original.id]);
        let after=original.after;
        // 新建节点按原意图世界位置转到 fresh owner，表现单位随其比例换算。
        if(after.structure==='node'){const basis=context.transforms.get(after.ownerCanvasId);if(!basis)throw fault('recovery_coordinate_context_missing',[after.id]);const destination=canvasTransform(document,after.ownerCanvasId),presentation=withUnitScale(after.data.presentation,unitScale(after.data.presentation)*basis.scale/destination.scale),data={...after.data};if(presentation===undefined)delete data.presentation;else data.presentation=presentation;after={...after,data,geometry:convertGeometry(after.geometry,basis,destination)};}
        // 新建边校验新端点代次，重新解算共同 owner，再转换原路径坐标。
        if(after.structure==='connection'){
          endpoint(after.source.elementId);endpoint(after.target.elementId);const owner=commonCanvas(document,document.elements.get(after.source.elementId)!.ownerCanvasId,document.elements.get(after.target.elementId)!.ownerCanvasId);
          const basis=context.transforms.get(after.ownerCanvasId);if(!basis)throw fault('recovery_coordinate_context_missing',[after.id]);
          after={...after,ownerCanvasId:owner,path:convertPath(after.path,basis,canvasTransform(document,owner))};
        }
        apply({...original,after});
      // 删除目标已不存在时直接满足，不在此以墓碑证明它曾是哪一代；仍存在则要求旧代次和已知类型。
      // 按 fresh 拥有树重新规划删除，可包含远端新增子内容/关联边，而不是照抄旧删除清单。
      }else if(original.before&&original.after===null){
        if(!current)continue;
        if(current.incarnation!==original.before.incarnation)throw fault('stale_incarnation',[original.id]);
        if(registry.resolve(current)!=='known')throw fault('unsupported_component',[original.id]);
        for(const change of removalChanges(document,{id:current.id,incarnation:current.incarnation}))apply(change);
      }else throw fault('recovery_record_replacement_not_supported',[original.id]);
      continue;
    }
    // 节点重挂会统一维护其入口子 canvas；其它树变化校验入口，删除非空 canvas 明确拒绝。
    if(original.kind==='canvas'){
      if(original.before?.parent&&original.after?.parent&&original.before.parent.entryElementId===original.after.parent.entryElementId&&moved.has(original.after.parent.entryElementId))continue;
      const current=document.canvases.get(original.id);
      if(!original.before&&original.after){if(current)throw fault('recovery_identity_collision',[original.id]);if(original.after.parent)endpoint(original.after.parent.entryElementId);apply(original);}
      else if(original.before&&!original.after){if(current){if(current.parent===null)throw fault('missing_root');for(const record of document.elements.values())if(record.ownerCanvasId===current.id)throw fault('recovery_canvas_not_empty',[current.id]);apply({...original,before:current});}}
      else if(original.after&&current){if(original.after.parent)endpoint(original.after.parent.entryElementId);const after={...current,parent:original.after.parent?{...current.parent,canvasId:original.after.parent.canvasId,entryElementId:original.after.parent.entryElementId}:null};if(!equal(current,after))apply({...original,before:current,after});}
      else throw fault('canvas_not_loaded',[original.id]);
      continue;
    }
    let current=target(original);const prior=context.before.get(current.id),afterContext=context.after.get(current.id);
    // 边 owner 留到最终端点/树确定后重算；节点重挂一次规划 owner+geometry+presentation+入口 parent。
    if(original.field==='ownerCanvasId'){
      if(current.structure==='connection')continue; // Recomputed from the final endpoints and tree below.
      if(!registry.supports(current,'geometry.move')||typeof original.after!=='string'||!document.canvases.has(original.after))throw fault('unsupported_capability',[current.id]);
      const basis=afterContext?context.transforms.get(afterContext.ownerCanvasId):undefined;if(!afterContext||afterContext.structure!=='node'||!basis)throw fault('recovery_coordinate_context_missing',[current.id]);
      const previous=context.before.get(current.id),originalSource=previous?context.beforeTransforms.get(previous.ownerCanvasId):undefined;
      if(current.structure!=='node'||previous?.structure!=='node'||!originalSource)throw fault('recovery_coordinate_context_missing',[current.id]);
      const converted=movedNode(current,previous,afterContext,originalSource,basis,canvasTransform(document,current.ownerCanvasId),canvasTransform(document,original.after),intent);
      if(current.ownerCanvasId!==original.after)apply({...original,before:current.ownerCanvasId});
      for(const canvas of document.canvases.values())if(canvas.parent?.entryElementId===current.id&&canvas.parent.canvasId!==original.after)apply({kind:'canvas',id:canvas.id,before:canvas,after:{...canvas,parent:{...canvas.parent,canvasId:original.after}}});
      if(!equal(current.data.presentation,converted.presentation))apply({kind:'field',target:original.target,field:'data.presentation',before:current.data.presentation??null,beforePresent:Object.hasOwn(current.data,'presentation'),after:converted.presentation??null,afterPresent:converted.presentation!==undefined});
      current=document.elements.get(current.id)!;if(current.structure==='node'&&!equal(current.geometry,converted.geometry))apply({kind:'field',target:original.target,field:'geometry',before:current.geometry,after:converted.geometry});
      continue;
    }
    // 已由重挂分支统一转换的几何/样式不再套旧字段变化，避免重复缩放或位移。
    if((original.field==='geometry'||original.field==='data.presentation')&&moved.has(current.id))continue;
    // 合并用户改过的样式键；unitScale 按原后空间与 fresh owner 换算，保留未改样式。
    if(original.field==='data.presentation'){
      const changedUnits=!closeScale(unitScale(original.before),unitScale(original.after));
      let desired=presentationDelta(current.data.presentation,original.before,original.after);
      if(changedUnits){const basis=afterContext?context.transforms.get(afterContext.ownerCanvasId):undefined;if(!basis)throw fault('recovery_coordinate_context_missing',[current.id]);desired=withUnitScale(desired,unitScale(original.after)*basis.scale/canvasTransform(document,current.ownerCanvasId).scale);}
      if(!equal(current.data.presentation,desired))apply({...original,before:current.data.presentation??null,beforePresent:Object.hasOwn(current.data,'presentation'),after:desired??null,afterPresent:desired!==undefined});
      continue;
    }

    // 换端点仍要求 connection.edit 与当前节点身份，相关曲线路径随后再处理。
    if(original.field==='source'||original.field==='target'){
      if(current.structure!=='connection'||!registry.supports(current,'connection.edit'))throw fault('unsupported_capability',[current.id]);
      const next=original.after as unknown as {elementId:Id};endpoint(next.elementId);
      if(!equal(current[original.field],original.after))apply({...original,before:current[original.field]});continue;
    }
    // 与 owner/端点同时改的路径延后；孤立几何/路径若 owner 已变则拒绝盲重放。
    if(original.field==='path'){
      const related=intent.changes.some(change=>change.kind==='field'&&change.target.id===current.id&&['ownerCanvasId','source','target'].includes(change.field));
      if(related){if(!registry.supports(current,'connection.edit'))throw fault('unsupported_capability',[current.id]);deferredPaths.push(original);continue;}
    }
    if((original.field==='geometry'||original.field==='path')&&prior&&prior.ownerCanvasId!==current.ownerCanvasId)throw fault('ownership_conflict',[current.id]);
    if(original.field.startsWith('data.')&&!registry.supports(current,'content.edit')||original.field==='path'&&!registry.supports(current,'connection.edit'))throw fault('unsupported_capability',[current.id]);
    const key=original.field.startsWith('data.')?original.field.slice(5):undefined,actual=key===undefined?(current as unknown as Record<string,Json>)[original.field]:current.data[key]??null,present=key===undefined?undefined:Object.hasOwn(current.data,key);
    let desired=original.after;
    // 普通几何修改仅覆盖 before→after 实际变化的轴，其余轴沿用 fresh；逐能力复核准入。
    if(original.field==='geometry'&&current.structure==='node'){
      const start=original.before as unknown as typeof current.geometry,end=original.after as unknown as typeof current.geometry;
      desired={...current.geometry,...Object.fromEntries((['x','y','width','height','rotation'] as const).filter(key=>start[key]!==end[key]).map(key=>[key,end[key]]))};
      const next=desired as unknown as typeof current.geometry;for(const [keys,capability]of [[['x','y'],'geometry.move'],[['width','height'],'geometry.resize'],[['rotation'],'geometry.rotate']] as const)if(keys.some(key=>current.geometry[key]!==next[key])&&!registry.supports(current,capability))throw fault('unsupported_capability',[current.id]);
    }
    if(!equal(actual,desired)||(present??true)!==(original.afterPresent??true)){const{beforePresent:_previous,...record}=original;apply({...record,before:actual,...(present===undefined?{}:{beforePresent:present}),after:desired});}
  }
  // 纯坐标转换造成的路径差异不当作用户改曲线；显式路径意图转到最终 owner 空间再发布候选。
  for(const original of deferredPaths){
    const edge=target(original),intended=context.after.get(edge.id);if(edge.structure!=='connection'||intended?.structure!=='connection')throw fault('invalid_endpoint',[edge.id]);
    const previous=context.before.get(edge.id),oldBasis=previous?context.beforeTransforms.get(previous.ownerCanvasId):undefined,basis=context.transforms.get(intended.ownerCanvasId);if(!basis)throw fault('recovery_coordinate_context_missing',[edge.id]);
    if(previous?.structure==='connection'&&oldBasis&&sameConvertedPath(convertPath(previous.path,oldBasis,basis),intended.path))continue;
    const owner=commonCanvas(document,document.elements.get(edge.source.elementId)!.ownerCanvasId,document.elements.get(edge.target.elementId)!.ownerCanvasId);
    const path=convertPath(original.after,basis,canvasTransform(document,owner));
    if(edge.ownerCanvasId!==owner)apply({kind:'field',target:original.target,field:'ownerCanvasId',before:edge.ownerCanvasId,after:owner});
    if(!equal(edge.path,path))apply({...original,before:edge.path,after:path});
  }
  // 使用初始 fresh 与最终候选修复受影响边的 owner/path，再做整图校验；空 changes 也要校验。
  // 抛错不返回半成品，成功仍只是规划结果；是否采纳以及新的 operation/history 身份由调用方决定。
  for(const change of repairConnectionOwners(before,document))apply(change);
  validateDocument(document,registry);return{document,changes:freeze(changes)};
}