Initial Commit

packages/localization/i18n/i18n-formatter-display-name/README.md

@@ -0,0 +1,106 @@
+# @suaveplan/i18n-formatter-display-name - Intl.DisplayNames wrapper for the @suaveplan/i18n family — locale-aware language/region/script/currency/calendar display names. Per-(locale, type, style, fallback) cache, Zod-validated options, OTel histogram + cache-hit counter, structured I18nError mapping. Universal leaf package.
+
+## Summary
+
+Wrapper around `Intl.DisplayNames` for the `@suaveplan/i18n` family —
+locale-aware language, region, script, currency, and calendar display
+names. Universal leaf package; depends only on
+`@suaveplan/i18n-shared`, `@suaveplan/types`, `@suaveplan/error`,
+`@opentelemetry/api`, and `zod`.
+
+<!-- begin:auto-docs -->
+## Documentation tree
+
+- [formatter](./src/formatter/formatter.md) — `DisplayNameFormatter` and the `formatDisplayName` standalone helper expose `Intl.DisplayNames` for the `@suaveplan/i18…
+  - [formatter](./src/formatter/formatter.md) — `DisplayNameFormatter` and the `formatDisplayName` standalone helper expose `Intl.DisplayNames` for the `@suaveplan/i18…
+- [helpers](./src/helpers/helpers.md) — The five ergonomic helpers (`formatLanguageName`, `formatRegionName`, `formatCurrencyName`, `formatScriptName`, `format…
+  - [helpers](./src/helpers/helpers.md) — The five ergonomic helpers (`formatLanguageName`, `formatRegionName`, `formatCurrencyName`, `formatScriptName`, `format…
+- [observability](./src/observability/observability.md) — The DisplayName formatter exports two OpenTelemetry instruments and a small in-memory state ring so spec-conformance te…
+  - [observability](./src/observability/observability.md) — The DisplayName formatter exports two OpenTelemetry instruments and a small in-memory state ring so spec-conformance te…
+<!-- end:auto-docs -->
+
+## Why this exists
+
+The 14-package i18n modular split (cross-cutting design
+`2026-05-05-i18n-modular-split.md`) lifts each `Intl.*` wrapper out of
+the monolith into its own sibling package. Lifting the display-name
+helper out of `@suaveplan/i18n` lets consumers that only need
+country-name / currency-name rendering pull a single small package
+instead of the entire i18n core.
+
+The package adds the canonical Wave-3 formatter shape on top of the
+monolith's standalone helper: Zod-validated options, a per-(locale,
+type, style, fallback) cache, OTel histogram + cache-hit counter, the
+class wrapper for symmetry with `NumberFormatter` /
+`RelativeTimeFormatter` / `ListFormatter` / `DateFormatter`, and five
+ergonomic helpers that pre-bind `formatDisplayName` with each
+canonical `type` value.
+
+## Install
+
+```bash
+bun add @suaveplan/i18n-formatter-display-name
+```
+
+## Quick Start
+
+```ts
+import {
+    DisplayNameFormatter,
+    formatDisplayName,
+    formatLanguageName,
+    formatRegionName,
+    formatCurrencyName,
+} from "@suaveplan/i18n-formatter-display-name";
+
+formatDisplayName("GB", "en-GB", { type: "region" }); // "United Kingdom"
+formatLanguageName("fr", "en-GB"); // "French"
+formatRegionName("US", "en-GB"); // "United States"
+formatCurrencyName("USD", "en-GB"); // "US Dollar"
+
+const f = new DisplayNameFormatter({ type: "region", style: "short" });
+f.format("DE", "en-GB"); // "Germany"
+```
+
+## Modules
+
+| Subpath | Description |
+|---|---|
+| `@suaveplan/i18n-formatter-display-name` | Root barrel — class + standalones + helpers + observability |
+| `@suaveplan/i18n-formatter-display-name/formatter` | `DisplayNameFormatter`, `formatDisplayName`, types, schema |
+| `@suaveplan/i18n-formatter-display-name/helpers` | Five ergonomic helpers — `formatLanguageName`, `formatRegionName`, `formatCurrencyName`, `formatScriptName`, `formatCalendarName` |
+
+## Modules Documentation
+
+- [formatter.md](src/formatter.md) — `DisplayNameFormatter` class, `formatDisplayName`, `clearDisplayNameCache`
+- [helpers.md](src/helpers.md) — five ergonomic helpers
+- [observability.md](src/observability.md) — OTel histogram + cache-hit counter
+
+## Public Surface (snapshot)
+
+| Export | Kind | Origin |
+|---|---|---|
+| `DisplayNameFormatter` | class | `formatter.ts` |
+| `formatDisplayName` | function | `formatter.ts` |
+| `clearDisplayNameCache` | function | `formatter.ts` |
+| `DisplayNameFormatterOptionsSchema` | Zod schema | `formatter.schemas.ts` |
+| `DisplayNameFormatterOptions` | type | `formatter.types.ts` |
+| `DisplayNameType` | type | `formatter.types.ts` |
+| `DisplayNameStyle` | type | `formatter.types.ts` |
+| `DisplayNameFallback` | type | `formatter.types.ts` |
+| `DisplayNameFormatterCacheKey` | type | `formatter.types.ts` |
+| `formatLanguageName` | function | `helpers.ts` |
+| `formatRegionName` | function | `helpers.ts` |
+| `formatCurrencyName` | function | `helpers.ts` |
+| `formatScriptName` | function | `helpers.ts` |
+| `formatCalendarName` | function | `helpers.ts` |
+| `recordDisplayNameFormat` | function | `observability.ts` |
+| `recordDisplayNameCacheHit` | function | `observability.ts` |
+| `getDisplayNameMetricsState` | function | `observability.ts` |
+| `resetDisplayNameMetricsState` | function | `observability.ts` |
+
+## Versioning
+
+Part of the 14-package i18n modular-split rollout. Stays at `0.1.0`
+until the slim core (Wave 6) cuts the family `1.0.0` release.
+