Fixed support for multi-langual slugs

src/modules/i18n/localizedPath.ts

@@ -1,5 +1,4 @@
 import type { I18nConfig } from './types.js'
-
 import { isValidLocale } from './helpers.js'
 
 /**
@@ -12,14 +11,22 @@ import { isValidLocale } from './helpers.js'
 export type LocalizedSlugs = Record<string, string>
 
 type BuildPathArgs = {
-  config: I18nConfig
-  /**
-   * Slug that represents the site root (served at /{locale} with no trailing
-   * segment). Defaults to 'home'. Matched against the slug in the target locale.
-   */
-  homeSlug?: string
+  /** slug per locale, e.g. { pl: 'strona-glowna', en: 'home' } */
+  slugs: LocalizedSlugs
   /** Target locale to build the path for */
   locale: string
+  config: I18nConfig
+  /**
+   * Slug(s) representing the site root (served at /{locale} with no trailing
+   * segment). Defaults to 'home'. Matched against the slug in the target locale.
+   *
+   * Can be a single string (same home slug in every locale) OR a per-locale map
+   * (`{ pl: 'strona-glowna', de: 'startseite', en: 'home' }`). The map form is
+   * REQUIRED for multilingual homepages whose slug differs per language —
+   * otherwise the home page collapses to '/pl' but '/de/startseite' stays
+   * un-collapsed, breaking hreflang return tags (a real GSC error).
+   */
+  homeSlug?: string | Record<string, string>
   /**
    * Localized segment the document lives under, e.g.
    * `{ pl: 'artykuly', en: 'articles' }` → /pl/artykuly/moj-post.
@@ -29,8 +36,6 @@ type BuildPathArgs = {
    * A document under a prefix is never the home page, so homeSlug is ignored.
    */
   prefix?: LocalizedSlugs
-  /** slug per locale, e.g. { pl: 'strona-glowna', en: 'home' } */
-  slugs: LocalizedSlugs
 }
 
 /**
@@ -56,11 +61,11 @@ type BuildPathArgs = {
  * // → '/en/articles/my-post'
  */
 export function buildLocalizedPath({
+  slugs,
+  locale,
   config,
   homeSlug = 'home',
-  locale,
   prefix,
-  slugs,
 }: BuildPathArgs): string | undefined {
   if (!isValidLocale(locale, config)) {
     return undefined
@@ -89,7 +94,13 @@ export function buildLocalizedPath({
     return `${localeSegment}/${segment}/${slug}`
   }
 
-  if (slug === homeSlug) {
+  // Resolve the home slug for THIS locale. With a per-locale map, each language
+  // has its own home slug (pl: 'strona-glowna', de: 'startseite'), so the check
+  // below correctly collapses each language's home to its root — instead of only
+  // the current-language slug matching and the others staying un-collapsed.
+  const targetHomeSlug = typeof homeSlug === 'object' ? homeSlug[locale] : homeSlug
+
+  if (slug === targetHomeSlug) {
     // Home collapses to the root: '/' for single-locale, '/pl' otherwise.
     return localeSegment || '/'
   }
@@ -98,11 +109,11 @@ export function buildLocalizedPath({
 }
 
 type SwitchLocaleArgs = {
-  config: I18nConfig
-  homeSlug?: string
-  prefix?: LocalizedSlugs
   slugs: LocalizedSlugs
   targetLocale: string
+  config: I18nConfig
+  homeSlug?: string | Record<string, string>
+  prefix?: LocalizedSlugs
 }
 
 /**
@@ -114,17 +125,17 @@ type SwitchLocaleArgs = {
  * to the locale root otherwise — the closest place the visitor would want.
  */
 export function switchLocalePath({
+  slugs,
+  targetLocale,
   config,
   homeSlug = 'home',
   prefix,
-  slugs,
-  targetLocale,
 }: SwitchLocaleArgs): string {
-  const path = buildLocalizedPath({ config, homeSlug, locale: targetLocale, prefix, slugs })
-  if (path) {return path}
+  const path = buildLocalizedPath({ slugs, locale: targetLocale, config, homeSlug, prefix })
+  if (path) return path
 
   const archiveSegment = prefix?.[targetLocale]
-  if (archiveSegment) {return `/${targetLocale}/${archiveSegment}`}
+  if (archiveSegment) return `/${targetLocale}/${archiveSegment}`
 
   return `/${targetLocale}`
 }