SEO: prevent locale-specific indexed Toolify guides linking to noindex tools

site/src/app/[locale]/tools/[slug]/page.tsx

@@ -64,7 +64,7 @@ export default async function ToolPage({
   const tt = await getTranslations(`tools.${slug}`);
   // index 対象ページの関連リンクは index 対象だけに絞る(権威を noindex へ流さない)。
   // noindex ページ側は従来どおり全ツールから出す — 利用者向けの導線で、クロール上の損が無い。
-  const related = getRelated(slug, 6, isIndexableIn(locale, slug));
+  const related = getRelated(slug, 6, isIndexableIn(locale, slug), locale);
   const url = `${siteConfig.url}/${locale}/tools/${slug}`;
 
   const faq = (tt.raw("faq") as { q: string; a: string }[]) ?? [];

site/src/lib/tools/registry.test.ts

@@ -94,3 +94,36 @@ describe("tool registry consistency", () => {
     }
   });
 });
+
+
+describe("SEO links match the locale-specific indexability policy", () => {
+  it("does not recommend noindex tool URLs from indexable exception locales", async () => {
+    const { getRelated, isIndexableIn } = await import("./registry");
+    const cases = [
+      ["th", "date-calculator"],
+      ["tr", "grade-calculator"],
+      ["ar", "length-converter"],
+      ["ru", "pressure-converter"],
+      ["es", "due-date-calculator"],
+      ["fr", "speed-converter"],
+      ["en", "workdays-calculator"],
+      ["ja", "date-calculator"],
+    ] as const;
+    for (const [locale, slug] of cases) {
+      expect(isIndexableIn(locale, slug), `${locale}/${slug} should be indexable`).toBe(true);
+      const related = getRelated(slug, 6, true, locale);
+      for (const target of related) {
+        expect(target.slug).not.toBe(slug);
+        expect(isIndexableIn(locale, target.slug),
+          `${locale}/${slug} should not link to noindex ${target.slug}`).toBe(true);
+      }
+      expect(new Set(related.map((tool) => tool.slug)).size).toBe(related.length);
+    }
+  });
+  it("leaves ordinary user navigation unrestricted on noindex pages", async () => {
+    const { getRelated } = await import("./registry");
+    const old = getRelated("date-calculator", 6, false);
+    const localized = getRelated("date-calculator", 6, false, "th");
+    expect(localized.map((x) => x.slug)).toEqual(old.map((x) => x.slug));
+  });
+});

site/src/lib/tools/registry.ts

@@ -600,13 +600,23 @@ const INBOUND_FROM_INDEXED: Map<string, number> = (() => {
  * 既定は false。noindex ツールのページでは noindex 同士を関連に出してよい
  * （利用者向けの導線であり、クロール上の損は無い）ため、絞るかは呼び出し側が決める。
  */
-export function getRelated(slug: string, limit = 5, indexableOnly = false): ToolMeta[] {
+export function getRelated(
+  slug: string,
+  limit = 5,
+  indexableOnly = false,
+  locale?: string,
+): ToolMeta[] {
   const tool = SLUG_INDEX.get(slug);
   if (!tool) return [];
-  const eligible = (m: ToolMeta) => !indexableOnly || INDEXED_SLUGS.has(m.slug);
+  // Pages indexed as locale-specific exceptions must NOT link to related
+  // tools that are noindex in that locale. CORE_TOOLS_BY_DEMAND covers en/ja
+  // broadly but does not imply indexability for ar/th/tr/ru/es/fr.
+  const eligible = (m: ToolMeta) => !indexableOnly ||
+    (locale ? isIndexableIn(locale, m.slug) : INDEXED_SLUGS.has(m.slug));
   const related = tool.related
     .map((s) => SLUG_INDEX.get(s))
     .filter((m): m is ToolMeta => Boolean(m))
+    .filter((m) => m.slug !== slug)
     .filter(eligible);
   if (related.length >= limit) return related.slice(0, limit);
   const fill = TOOLS