Fix blog dates ignoring the page locale

packages/sitetile/astro/src/components/ArchiveView.astro

@@ -76,7 +76,7 @@ const archive = showSidebar ? groupByArchive(corpus) : [];
                 <span class="bl-date-year">{dateBadgeParts(p.date, meta.lang).year}</span>
               </time>
             ) : (
-              <time class="bl-date">{fmtDate(p.date, dateFormat)}</time>
+              <time class="bl-date">{fmtDate(p.date, dateFormat, meta.lang)}</time>
             ))}
             <h2 class="bl-title">{p.title}</h2>
             {(p.description || p.excerpt) && <p class="bl-desc">{p.description || p.excerpt}</p>}

packages/sitetile/astro/src/components/BlogIndexView.astro

@@ -89,7 +89,7 @@ const title = isHome
                 <span class="bl-date-year">{dateBadgeParts(p.date, meta.lang).year}</span>
               </time>
             ) : (
-              <time class="bl-date">{fmtDate(p.date, dateFormat)}</time>
+              <time class="bl-date">{fmtDate(p.date, dateFormat, meta.lang)}</time>
             ))}
             <h2 class="bl-title">{p.title}</h2>
             {(p.description || p.excerpt) && <p class="bl-desc">{p.description || p.excerpt}</p>}

packages/sitetile/astro/src/components/PostArticle.astro

@@ -13,7 +13,9 @@ import { safeHref } from '@sitetile';
 
 const { post, meta, newer, older, keepReadingCards, relatedCards } = Astro.props;
 // blog-date-format (home meta): cjk-badge falls back to cjk-full's full string here —
-// the three-span badge layout is index-cards-only (see blog.mjs fmtDate()).
+// the three-span badge layout is index-cards-only (see blog.mjs fmtDate()). Absent/unrecognised
+// (cjk is an alias of cjk-full) falls to fmtDate's own locale default, which is why this page's
+// own `meta.lang` — not the site default — is what gets passed to it below.
 const dateFormat = meta['blog-date-format'];
 // blog-post-linebreaks: br → WP-wpautop mode (single newline inside a paragraph → <br>), for
 // WP-sourced recasts whose live keeps manual line breaks. Default (unset) = CommonMark join.
@@ -93,7 +95,7 @@ const crumbBlog = String(meta['blog-title'] || 'Blog').trim();
     <a class="bl-back" href={blogBase(meta)}><Arrow direction="left" size={14} />All posts</a>
   )}
   <header class="bl-post-head">
-    {post.date && <time class="bl-date">{fmtDate(post.date, dateFormat)}</time>}
+    {post.date && <time class="bl-date">{fmtDate(post.date, dateFormat, meta.lang)}</time>}
     <h1>{post.title}</h1>
     {author && <p class="bl-byline">{bylineLabel} {author}</p>}
     {/* 🩸 added 2026-07-13: top-of-post share pair (see topShareLinks above) — matches live
@@ -122,14 +124,14 @@ const crumbBlog = String(meta['blog-title'] || 'Blog').trim();
       {newer ? (
         <a class="bl-post-nav-item bl-post-nav-newer" href={postUrl(newer, meta)}>
           <span class="bl-post-nav-label"><Arrow direction="left" size={12} />{newerLabel}</span>
-          {newer.date && <span class="bl-post-nav-date">{fmtDate(newer.date, dateFormat)}</span>}
+          {newer.date && <span class="bl-post-nav-date">{fmtDate(newer.date, dateFormat, meta.lang)}</span>}
           <span class="bl-post-nav-title">{newer.title}</span>
         </a>
       ) : <span />}
       {older && (
         <a class="bl-post-nav-item bl-post-nav-older" href={postUrl(older, meta)}>
           <span class="bl-post-nav-label">{olderLabel}<Arrow direction="right" size={12} /></span>
-          {older.date && <span class="bl-post-nav-date">{fmtDate(older.date, dateFormat)}</span>}
+          {older.date && <span class="bl-post-nav-date">{fmtDate(older.date, dateFormat, meta.lang)}</span>}
           <span class="bl-post-nav-title">{older.title}</span>
         </a>
       )}
@@ -143,7 +145,7 @@ const crumbBlog = String(meta['blog-title'] || 'Blog').trim();
           <li>
               <a href={p.href}>
               {p.image && <img class="bl-keep-img" src={p.image} alt="" loading="lazy" />}
-              {p.date && <time datetime={p.date}>{fmtDate(p.date, dateFormat)}</time>}
+              {p.date && <time datetime={p.date}>{fmtDate(p.date, dateFormat, meta.lang)}</time>}
               <h3>{p.title}</h3>
               {p.description && <p>{p.description}</p>}
             </a>
@@ -160,7 +162,7 @@ const crumbBlog = String(meta['blog-title'] || 'Blog').trim();
           <li>
               <a href={p.href}>
               {p.image && <img class="bl-keep-img" src={p.image} alt="" loading="lazy" />}
-              {p.date && <time datetime={p.date}>{fmtDate(p.date, dateFormat)}</time>}
+              {p.date && <time datetime={p.date}>{fmtDate(p.date, dateFormat, meta.lang)}</time>}
               <h3>{p.title}</h3>
               {p.description && <p>{p.description}</p>}
             </a>

packages/sitetile/astro/src/lib/blog.mjs

@@ -8,9 +8,10 @@ import { splitFrontmatter, bodyHtml, inlineHtml, parseSite, safeHref, safeSrc }
 // it. Re-exported here because every component already imports these from blog.mjs — the seam
 // moved, the call sites did not.
 export { sidebarCopy, unquote, archivePrefixes, dateBadgeParts } from './chrome-copy.mjs';
-// toUrlLocale is a pure string transform (no @sitetile import), so pulling it in here costs
-// nothing a plain `node` test can't already afford — sitemap.mjs already does the same cross-import.
-import { toUrlLocale } from '../packages/lingo/locale.mjs';
+// toUrlLocale / toBcp47 are pure string transforms (no @sitetile import), so pulling them in here
+// costs nothing a plain `node` test can't already afford — sitemap.mjs already does the same
+// cross-import.
+import { toUrlLocale, toBcp47 } from '../packages/lingo/locale.mjs';
 
 const FM_LIST_RE = /^\[(.*)\]$/;
 const PRIVACY_FRONTMATTER = /^---\r?\n([\s\S]*?)\r?\n---(?:\r?\n|$)/;
@@ -496,14 +497,78 @@ export function groupByArchive(posts) {
   }));
 }
 
-// fmtDate: format a pubDate string per the `blog-date-format` meta key (home.md
-// frontmatter). Default (format is undefined/unrecognized) = the historic
-// en-US "June 25, 2026" — kept byte-identical to the original inline arrow fn so
-// existing output never changes when the meta key is absent.
-export function fmtDate(s, format) {
+// The `blog-date-format` values fmtDate recognises — named here once so the unknown-value warning
+// can quote the exact list rather than a copy of it going stale next to the switch below.
+const KNOWN_DATE_FORMATS = ['ymd-slash', 'cjk', 'cjk-full', 'cjk-badge', 'cjk-md'];
+
+// `cjk-full` / `cjk-badge` / `cjk-md` (and the `cjk` alias) are a script, not a punctuation style —
+// an owner who writes `blog-date-format: cjk` is choosing that layout for the pages that read in a
+// CJK script. Ruling (2026-09-11, github.com/CVERInc/tile#34 round 1): these formats apply to the
+// PAGE's own locale when that locale is Japanese, Korean, or Chinese, and fall back to that page's
+// own Intl default everywhere else — an English page on the same multilingual site keeps reading
+// "July 13, 2024", not "2024 年 7 月 13 日". `ymd-slash` carries no script, so it is exempt from this
+// gate and always applies, on every locale, as before.
+const CJK_DATE_FORMATS = new Set(['cjk-full', 'cjk-badge', 'cjk-md']);
+// Primary BCP-47 subtag test, done on the page's OWN raw `lang:` value (whatever an author wrote —
+// `ja-JP`, `zh-Hant`, `zh-TW`, bare `zh`…) rather than routing it through toBcp47() first, so a
+// tag toBcp47 cannot canonicalise (an unrecognised or malformed value) still gets a straight answer
+// here instead of silently reading as non-CJK.
+function isCJKLang(lang) {
+  const primary = String(lang || '').toLowerCase().split(/[-_]/)[0];
+  return primary === 'ja' || primary === 'ko' || primary === 'zh';
+}
+
+// The shared "no named format" renderer: the page's own locale via Intl, falling back to en-US
+// when no locale is known (byte-identical historic output) AND when the locale IS known but is not
+// a tag Intl accepts — a site's `lang:` is free text (a typo, an underscore instead of a hyphen, a
+// value nobody ever validated against BCP-47), and `new Intl.DateTimeFormat()` throws a RangeError
+// on anything it cannot parse rather than degrading gracefully. Before this guard that RangeError
+// crashed the whole build on the very first date it tried to render (github.com/CVERInc/tile#34
+// review round 1, P1-1) — the safe fallback is worse-looking dates, never a build that cannot ship.
+function localeDefaultDate(d, lang) {
+  const opts = { year: 'numeric', month: 'long', day: 'numeric' };
+  const tag = lang ? toBcp47(lang) : 'en-US';
+  try {
+    return new Intl.DateTimeFormat(tag, opts).format(d);
+  } catch {
+    return new Intl.DateTimeFormat('en-US', opts).format(d);
+  }
+}
+
+// A build renders every post's date once per locale, so an unrecognised `blog-date-format` would
+// otherwise warn hundreds of times for the one config line that is wrong. Keyed by the raw value,
+// not a single flag, so a site that (mis)configures two different bad values still hears about
+// both — module-scoped state, reset per build (a fresh process / fresh import).
+const warnedDateFormats = new Set();
+function warnUnknownDateFormat(format) {
+  if (format == null || format === '' || warnedDateFormats.has(format)) return;
+  warnedDateFormats.add(format);
+  console.warn(`[sitetile] Unrecognised blog-date-format "${format}" — expected one of: ${KNOWN_DATE_FORMATS.join(', ')}. Falling back to the page's own language.`);
+}
+
+// fmtDate: format a pubDate string per the `blog-date-format` meta key (home.md frontmatter).
+// `lang` is THIS PAGE's own locale (the Lingo variant being rendered — metaL.lang on a translated
+// page, the site default elsewhere), never the site's default language on a page rendering a
+// different one. Default (format is undefined/unrecognised) formats with that locale via Intl, so
+// a ja-JP page reads "2024年7月13日" and an en-US one "July 13, 2024" — no locale known (lang
+// absent) keeps the historic literal en-US output byte-identical, and an unparseable lang tag
+// (RangeError from Intl) degrades to that same en-US output rather than crashing the build.
+// `cjk` is accepted as an alias of `cjk-full` (the value people reach for); any other unrecognised
+// value falls to the locale default AND names the allowed values in a build-time warning, once per
+// build per bad value — a site whose config looks right and silently does nothing was the bug.
+// An explicit CJK format (`cjk`/`cjk-full`/`cjk-badge`/`cjk-md`) is scoped to CJK page locales
+// (ja / zh-* / ko, see isCJKLang) — a non-CJK page locale renders ITS OWN locale default instead,
+// same as an unrecognised format would (see CJK_DATE_FORMATS above). `lang` absent keeps the
+// historic behaviour of always rendering the named format, since there is no page locale to gate
+// on. `ymd-slash` has no script and is never gated.
+export function fmtDate(s, format, lang) {
   const d = new Date(s);
   if (isNaN(d)) return s;
-  switch (format) {
+  const fmt = format === 'cjk' ? 'cjk-full' : format;
+  if (CJK_DATE_FORMATS.has(fmt) && lang && !isCJKLang(lang)) {
+    return localeDefaultDate(d, lang);
+  }
+  switch (fmt) {
     case 'ymd-slash': // 2026/05/20
       return `${d.getFullYear()}/${String(d.getMonth() + 1).padStart(2, '0')}/${String(d.getDate()).padStart(2, '0')}`;
     case 'cjk-full': // 2025 年 11 月 11 日
@@ -512,7 +577,8 @@ export function fmtDate(s, format) {
     case 'cjk-md': // 4月8日
       return `${d.getMonth() + 1}月${d.getDate()}日`;
     default:
-      return d.toLocaleDateString('en-US', { year: 'numeric', month: 'long', day: 'numeric' });
+      warnUnknownDateFormat(fmt);
+      return localeDefaultDate(d, lang);
   }
 }
 

packages/sitetile/astro/src/pages/search/label/[tag]/index.astro

@@ -109,7 +109,7 @@ const pageHref = (n) => (n === 1 ? `/search/label/${tag}` : `/search/label/${tag
                 <span class="bl-date-year">{dateBadgeParts(p.date, meta.lang).year}</span>
               </time>
             ) : (
-              <time class="bl-date">{fmtDate(p.date, dateFormat)}</time>
+              <time class="bl-date">{fmtDate(p.date, dateFormat, meta.lang)}</time>
             ))}
             <h2 class="bl-title">{p.title}</h2>
             {(p.description || p.excerpt) && <p class="bl-desc">{p.description || p.excerpt}</p>}

packages/sitetile/astro/src/pages/search/label/[tag]/page/[n].astro

@@ -91,7 +91,7 @@ const pageHref = (n) => (n === 1 ? `/search/label/${tag}` : `/search/label/${tag
                 <span class="bl-date-year">{dateBadgeParts(p.date, meta.lang).year}</span>
               </time>
             ) : (
-              <time class="bl-date">{fmtDate(p.date, dateFormat)}</time>
+              <time class="bl-date">{fmtDate(p.date, dateFormat, meta.lang)}</time>
             ))}
             <h2 class="bl-title">{p.title}</h2>
             {(p.description || p.excerpt) && <p class="bl-desc">{p.description || p.excerpt}</p>}