feat: add markdown update history

src/lib/components/UpdateNotice.svelte

@@ -1,12 +1,14 @@
 <script lang="ts">
   import { onMount } from 'svelte';
   import { dev } from '$app/environment';
+  import updateHistoryMarkdown from '../../../UPDATES.md?raw';
   import { renderReleaseMarkdown } from '$lib/release-notes/markdown';
-  import { RELEASES_PAGE_URL } from '$lib/release-notes/release-note-service';
   import { currentAppVersion, releaseNotes } from '$lib/release-notes/release-note-store';
   import { versionTagIsNewer } from '$lib/release-notes/version';
+  import { parseUpdateHistoryDocument } from '$lib/update-history-document.ts';
 
   let previewUpdate = false;
+  const updateHistoryDocument = parseUpdateHistoryDocument(updateHistoryMarkdown);
 
   onMount(() => {
     previewUpdate = dev && new URLSearchParams(window.location.search).get('previewUpdate') === '1';
@@ -16,6 +18,20 @@
   $: latestRelease = $releaseNotes.releases[0] ?? null;
   $: updateAvailable = latestRelease !== null && (previewUpdate || versionTagIsNewer(latestRelease.tagName, currentAppVersion));
 
+  function updatedDateTime(value: string | null): string {
+    if (!value) return '시각 미등록';
+    const date = new Date(value);
+    if (Number.isNaN(date.getTime())) return value;
+    return new Intl.DateTimeFormat('ko-KR', {
+      year: 'numeric',
+      month: 'long',
+      day: 'numeric',
+      hour: '2-digit',
+      minute: '2-digit',
+      hour12: false
+    }).format(date);
+  }
+
   function publishedDate(value: string): string {
     const date = new Date(value);
     if (Number.isNaN(date.getTime())) return value;
@@ -27,25 +43,22 @@
   }
 </script>
 
-{#if $releaseNotes.status === 'available' && latestRelease}
-  <aside class:available={updateAvailable} class="update-notice" aria-live="polite">
+<aside class:available={updateAvailable} class="update-notice" aria-live="polite">
     <div class="notice-header">
       <div class="version-summary">
-        <span class="label">현재 버전</span>
-        <strong>v{currentAppVersion.replace(/^v/i, '')}</strong>
+        <span class="label">최근 업데이트</span>
+        <strong><time datetime={updateHistoryDocument.updatedAt ?? undefined}>{updatedDateTime(updateHistoryDocument.updatedAt)}</time></strong>
         {#if previewUpdate}
           <span class="status"><b>업데이트 알림 미리보기</b></span>
         {:else if updateAvailable}
           <span class="status"><b>{latestRelease.tagName}</b> 업데이트를 사용할 수 있습니다.</span>
-        {:else}
-          <span class="status">최신 버전입니다.</span>
         {/if}
       </div>
 
-      <a class="action" href={RELEASES_PAGE_URL} target="_blank" rel="noreferrer">업데이트 내역 확인 <span aria-hidden="true">→</span></a>
+      <a class="action" href="/updates">업데이트 내역 확인 <span aria-hidden="true">→</span></a>
     </div>
 
-    {#if updateAvailable}
+    {#if updateAvailable && latestRelease}
       <section class="latest-note" aria-labelledby="latest-release-title">
         <header>
           <div>
@@ -62,8 +75,7 @@
         {/if}
       </section>
     {/if}
-  </aside>
-{/if}
+</aside>
 
 <style>
   .update-notice { margin-bottom: 12px; border: 1px solid #2c3440; border-radius: 12px; background: #151a22; overflow: hidden; }

src/lib/engine/update-history-document.test.ts

@@ -0,0 +1,15 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { parseUpdateHistoryDocument } from '../update-history-document.ts';
+
+test('업데이트 Markdown의 최근 업데이트 시각을 본문과 분리한다', () => {
+  const document = parseUpdateHistoryDocument('---\nupdatedAt: 2026-08-31T14:15:17+09:00\n---\n\n## 업데이트');
+
+  assert.equal(document.updatedAt, '2026-08-31T14:15:17+09:00');
+  assert.equal(document.body, '\n## 업데이트');
+});
+
+test('메타데이터가 없는 Markdown도 그대로 표시한다', () => {
+  const markdown = '## 업데이트';
+  assert.deepEqual(parseUpdateHistoryDocument(markdown), { updatedAt: null, body: markdown });
+});

src/lib/update-history-document.ts

@@ -0,0 +1,19 @@
+export type UpdateHistoryDocument = {
+  updatedAt: string | null;
+  body: string;
+};
+
+export function parseUpdateHistoryDocument(markdown: string): UpdateHistoryDocument {
+  const frontmatter = markdown.match(/^---\r?\n([\s\S]*?)\r?\n---(?:\r?\n|$)/);
+  if (!frontmatter) return { updatedAt: null, body: markdown };
+
+  const updatedAt = frontmatter[1]
+    .split(/\r?\n/)
+    .map((line) => line.match(/^updatedAt:\s*(.+?)\s*$/)?.[1] ?? null)
+    .find((value): value is string => value !== null) ?? null;
+
+  return {
+    updatedAt,
+    body: markdown.slice(frontmatter[0].length)
+  };
+}