@logistics-ts/inventory

Inventory decision-support for logistics-ts: safety stock, reorder point / order-up-to level, EOQ/EPQ (with quantity discounts), coverage, turnover, and a catalogue-wide issue analyser. Every result returns Explained<T>.

Install

npm i @logistics-ts/inventory

What's in it

• safetyStock — the safety-stock buffer for a target cycle service level; method: 'auto' picks the right formula for whatever variability data you supply (demand only, lead time only, or both — King's combined formula).
• reorderPoint / orderUpToLevel — the reorder trigger, or the order-up-to level for periodic review.
• eoq / epq / eoqWithQuantityDiscounts — order-quantity sizing (classic EOQ, finite production rate, price breaks).
• coverage / turnover — days of inventory on hand / annual turns, always reported in calendar days regardless of demand-bucketing granularity.
• issues — one call that flags every item needing attention across a catalogue: below-rop, below-safety-stock, stockout-risk-within-leadtime, overstocked, dead-stock.

Quick start

import { generateExampleData, mean, standardDeviation } from '@logistics-ts/core'
import { reorderPoint, safetyStock } from '@logistics-ts/inventory'

const { demand, leadTimes } = generateExampleData({ items: 1, periods: 24, seed: 4 })
const itemId = demand[0]!.itemId
const quantities = demand.filter((d) => d.itemId === itemId).map((d) => d.quantity)
const itemLeadTimes = leadTimes.filter((l) => l.itemId === itemId).map((l) => l.leadTimeDays)

const ss = safetyStock(
  {
    meanDemand: mean(quantities),
    meanLeadTime: mean(itemLeadTimes),
    demandStdDev: standardDeviation(quantities),
  },
  { method: 'auto', serviceLevel: 0.95 },
)

const rop = reorderPoint({
  meanDemand: mean(quantities),
  meanLeadTime: mean(itemLeadTimes),
  safetyStock: ss.value,
})

console.log(ss.value, ss.method, ss.reasoning)
console.log(rop.value) // reorder when on-hand stock drops to this level

meanDemand and meanLeadTime must share a period unit — LeadTimeRecord is always in days, so convert it before combining with weekly/monthly demand (the issues function below does this for you).

For the whole "flag everything that needs reordering" flow in one call:

import { issues } from '@logistics-ts/inventory'

const problems = issues(stock, demand, leadTimes, { serviceLevel: 0.95, granularity: 'month' })

In the umbrella package

@logistics-ts/inventory is re-exported as the inventory namespace from logistics-ts, which also adds a stateful InventoryAnalyzer convenience wrapper over this package's pure functions. @logistics-ts/inventory depends on @logistics-ts/core, @logistics-ts/classification, and @logistics-ts/forecasting.

Links

• Full docs, API map, and examples
• Other logistics-ts packages

License

MIT