校园外卖先小程序还是App？多端订单命令怎样避免覆盖状态

'use strict';
const assert = require('node:assert/strict');
const {createHash} = require('node:crypto');
class Orders {
  constructor() { this.orders = new Map(); this.receipts = new Map(); }
  create(tenant, id, campus) {
    const ref = JSON.stringify([tenant, id]);
    if (this.orders.has(ref)) throw Error('duplicate order');
    this.orders.set(ref, {campus, state:'READY', revision:0});
  }
  execute(ctx, id, key, expected, action) {
    const ref = JSON.stringify([ctx.tenant, id]);
    const row = this.orders.get(ref);
    if (!row || !ctx.campuses.includes(row.campus)) return {status:403};
    if (!['rider','operator'].includes(ctx.role)) return {status:403};
    if (action === 'CANCEL' && ctx.role !== 'operator') return {status:403};
    if (typeof key !== 'string' || !key.trim()) return {status:400};
    const digest = createHash('sha256').update(JSON.stringify({action})).digest('hex');
    const commandRef = JSON.stringify([ctx.tenant,id,key]);
    const prior = this.receipts.get(commandRef);
    const current = () => structuredClone(row);
    if (prior) return prior.digest === digest
      ? {status:200,replayed:true,commandResult:structuredClone(prior.result),current:current()}
      : {status:409,error:'KEY_CONFLICT'};
    if (!Number.isSafeInteger(expected) || expected !== row.revision)
      return {status:409,error:'VERSION_CONFLICT'};
    const transitions = {
      READY:{ACCEPT:'ACCEPTED',CANCEL:'CANCELLED'},
      ACCEPTED:{HANDOVER:'HANDED_OVER'}, HANDED_OVER:{COMPLETE:'DONE'}
    };
    const next = transitions[row.state]?.[action];
    if (!next) return {status:409,error:'STATE_CONFLICT'};
    // Single-process teaching model: synchronous mutation, no disk or network.
    row.state = next; row.revision++;
    const result = current();
    this.receipts.set(commandRef,{digest,result:structuredClone(result)});
    return {status:200,replayed:false,commandResult:result,current:current()};
  }
}
const db = new Orders(); db.create('T','O1','C');
const actor = {tenant:'T',role:'rider',campuses:['C']};
let checks=0;
function eq(a,b) { assert.deepEqual(a,b); checks++; }
let r=db.execute(actor,'O1','K1',0,'ACCEPT');
eq(r.status,200); eq(r.current.state,'ACCEPTED'); eq(r.current.revision,1);
r=db.execute(actor,'O1','K1',0,'ACCEPT');
eq(r.replayed,true); eq(r.current.revision,1);
eq(db.execute(actor,'O1','K1',1,'HANDOVER').error,'KEY_CONFLICT');
eq(db.execute(actor,'O1','K2',0,'ACCEPT').error,'VERSION_CONFLICT');
eq(db.execute(actor,'O1','K3',1,'ACCEPT').error,'STATE_CONFLICT');
eq(db.execute({...actor,role:'student'},'O1','X',1,'HANDOVER').status,403);
eq(db.execute({...actor,campuses:['D']},'O1','X',1,'HANDOVER').status,403);
eq(db.execute(actor,'O1','K4',1,'HANDOVER').current.revision,2);
eq(db.execute(actor,'O1','K5',2,'COMPLETE').current.revision,3);
r=db.execute(actor,'O1','K1',0,'ACCEPT');
eq(r.commandResult.revision,1); eq(r.current.revision,3);
r.current.state='CORRUPTED';
eq(db.execute(actor,'O1','K1',0,'ACCEPT').current.state,'DONE');
db.create('OTHER','O1','C');
eq(db.execute({...actor,tenant:'OTHER'},'O1','K1',0,'ACCEPT').current.revision,1);
console.log(JSON.stringify({passed:checks,oldReceiptRevision:1,currentOrderRevision:3,
 scope:'local sequential in-memory example; no database, cloud or product test'}));