fix: entity on description / additional overrides on update subscription

shared/utils/productUtils/priceUtils/findTier/findTierByOptions.ts

@@ -0,0 +1,36 @@
+import type { FeatureOptions } from "@models/cusProductModels/cusProductModels";
+import type {
+	UsagePriceConfig,
+	UsageTier,
+} from "@models/productModels/priceModels/priceConfig/usagePriceConfig";
+import type { Price } from "@models/productModels/priceModels/priceModels";
+import { findTierByQuantity } from "./findTierByQuantity";
+
+/**
+ * Find the volume-tier the customer is currently on, given a prepaid `Price`
+ * and the matching `FeatureOptions` entry from `cusProduct.options`.
+ *
+ * Convention (Autumn prepaid):
+ *  - `options.quantity` is in PACKS and EXCLUDES the entitlement allowance.
+ *  - Tier `to` boundaries on the price are paid-only — they also EXCLUDE the
+ *    allowance.
+ *  - Lookup quantity = `options.quantity * billing_units` (paid credits).
+ *
+ * Returns the matching tier (or undefined when no tier covers the quantity —
+ * shouldn't happen if the tier list ends with `Infinite`).
+ */
+export const findTierByOptions = ({
+	price,
+	options,
+}: {
+	price: Price;
+	options: FeatureOptions | undefined;
+}): UsageTier | undefined => {
+	const config = price.config as UsagePriceConfig;
+	const billingUnits = config.billing_units ?? 1;
+	const paidQuantity = (options?.quantity ?? 0) * billingUnits;
+	return findTierByQuantity({
+		tiers: config.usage_tiers ?? [],
+		quantity: paidQuantity,
+	});
+};

shared/utils/productUtils/priceUtils/findTier/findTierByQuantity.ts

@@ -0,0 +1,23 @@
+import type { UsageTier } from "@models/productModels/priceModels/priceConfig/usagePriceConfig";
+import { Infinite } from "@models/productModels/productEnums";
+
+/**
+ * Find the volume-tier that covers the given quantity. Walks tiers in order
+ * and returns the first one whose `to` is ≥ quantity (or the final Infinite
+ * tier). Returns undefined only if no Infinite tier exists and quantity
+ * exceeds every bound — tier shapes are expected to end with `to: Infinite`,
+ * so this is rare.
+ */
+export const findTierByQuantity = ({
+	tiers,
+	quantity,
+}: {
+	tiers: UsageTier[];
+	quantity: number;
+}): UsageTier | undefined => {
+	for (const tier of tiers) {
+		if (tier.to === Infinite || tier.to === -1) return tier;
+		if (typeof tier.to === "number" && quantity <= tier.to) return tier;
+	}
+	return undefined;
+};