IdleKit

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Formatting ​

Economy returns strings and UI-agnostic view models. It does not render DOM, choose icons or own layout.

ts
import { createEconomy, describeFailure, stateKey } from "@idlekitjs/economy";

Amounts ​

economy.formatAmount(resourceId, amount) formats one amount using the resource formatter, then the economy-wide formatter, then String.

ts
const economy = createEconomy<State>({
  format: (amount) => Math.floor(amount).toLocaleString("en-US"),
}).resource({
  id: "currency:coins",
  label: "Coins",
  accessor: stateKey("coins"),
});

economy.formatAmount("currency:coins", 1200); // "1,200"

Costs ​

economy.formatCost(state, cost) returns one FormattedCostLine per normalized line.

ts
const lines = economy.formatCost(state, [["currency:coins", 100]]);

for (const line of lines) {
  line.resourceId;
  line.label;
  line.amount; // formatted text
  line.rawAmount;
  line.available; // spendable balance
  line.affordable;
}

Rewards ​

economy.formatReward(reward) returns FormattedAmount view models without affordability fields.

ts
const rewards = economy.formatReward([["currency:coins", 25]]);

Failures ​

describeFailure(failure, options?) returns a default English sentence for a transaction failure.

ts
const preview = economy.preview(state, transaction);

const text = preview.failures
  .map((failure) =>
    describeFailure(failure, {
      label: (id) => economy.resource(id).label,
    }),
  )
  .join("\n");

For localized or styled UIs, switch on failure.kind directly.