feat(posts): search + year filter + upcoming events on tag routes

Extracts buildPostSearchIndex + selectUpcomingEvents into blog-utils so
all four routes (posts index, posts pagination, tag, tag pagination)
share the same feature set.

src/lib/blog-utils.ts

@@ -171,6 +171,48 @@ export function postHref(post: PostEntry): string {
   return norm ? `${POST_BASE}/${encodeURIComponent(norm)}` : POST_BASE;
 }
 
+export type PostSearchIndexEntry = {
+  slug: string;
+  headline: string;
+  excerpt: string;
+  subheadline: string;
+  tags: string[];
+  image: string | null;
+  created: string | null;
+  isEvent: boolean;
+  eventDate: string | null;
+};
+
+type PostWithEvent = PostEntry & {
+  isEvent?: boolean;
+  eventDate?: string;
+  _resolvedImageUrl?: string;
+};
+
+export function buildPostSearchIndex(posts: PostEntry[]): PostSearchIndexEntry[] {
+  return posts.map((p) => ({
+    slug: p.slug ?? p._slug ?? "",
+    headline: p.headline ?? "",
+    excerpt: p.excerpt ?? "",
+    subheadline: p.subheadline ?? "",
+    tags: (p.postTag ?? [])
+      .map((t) => (typeof t === "string" ? t : (t as { name?: string; _slug?: string }).name ?? (t as { _slug?: string })._slug ?? ""))
+      .filter(Boolean),
+    image: (p as PostWithEvent)._resolvedImageUrl ?? null,
+    created: p.created ?? null,
+    isEvent: Boolean((p as PostWithEvent).isEvent),
+    eventDate: (p as PostWithEvent).eventDate ?? null,
+  }));
+}
+
+export function selectUpcomingEvents(posts: PostEntry[], max = 4): PostEntry[] {
+  const now = Date.now();
+  return (posts as PostWithEvent[])
+    .filter((p) => p.isEvent && p.eventDate && new Date(p.eventDate).getTime() >= now)
+    .sort((a, b) => new Date(a.eventDate ?? 0).getTime() - new Date(b.eventDate ?? 0).getTime())
+    .slice(0, max) as PostEntry[];
+}
+
 export function formatPostDate(value: string | undefined): string {
   if (!value) return "";
   try {

src/pages/posts/index.astro

@@ -15,6 +15,8 @@ import {
   getTagsMap,
   resolvePostTagsInPost,
   getPostImageUrl,
+  buildPostSearchIndex,
+  selectUpcomingEvents,
 } from '../../lib/blog-utils';
 import { t, T } from '../../lib/translations';
 
@@ -49,29 +51,8 @@ const filtered = filterPostsByTag(posts, null);
 const totalPages = getTotalPages(filtered.length, perPage);
 const pagePosts = paginate(filtered, 1, perPage);
 
-type PostWithEvent = (typeof posts)[number] & {
-  isEvent?: boolean;
-  eventDate?: string;
-  _resolvedImageUrl?: string;
-};
-const nowMs = Date.now();
-const upcomingEvents = (posts as PostWithEvent[])
-  .filter((p) => p.isEvent && p.eventDate && new Date(p.eventDate).getTime() >= nowMs)
-  .sort((a, b) => new Date(a.eventDate ?? 0).getTime() - new Date(b.eventDate ?? 0).getTime())
-  .slice(0, 4);
-
-// Lightweight index for client-side search over the full archive.
-const searchIndex = posts.map((p) => ({
-  slug: p.slug ?? p._slug ?? "",
-  headline: p.headline ?? "",
-  excerpt: p.excerpt ?? "",
-  subheadline: p.subheadline ?? "",
-  tags: (p.postTag ?? []).map((t) => (typeof t === "string" ? t : (t as { name?: string; _slug?: string }).name ?? (t as { _slug?: string })._slug ?? "")).filter(Boolean),
-  image: (p as PostWithEvent)._resolvedImageUrl ?? null,
-  created: p.created ?? null,
-  isEvent: Boolean((p as PostWithEvent).isEvent),
-  eventDate: (p as PostWithEvent).eventDate ?? null,
-}));
+const upcomingEvents = selectUpcomingEvents(posts);
+const searchIndex = buildPostSearchIndex(posts);
 
 const translations = Astro.locals.translations ?? {};
 ---

src/pages/posts/page/[page].astro

@@ -10,6 +10,8 @@ import {
   paginate,
   getPostsPerPage,
   getPostImageUrl,
+  buildPostSearchIndex,
+  selectUpcomingEvents,
 } from '../../../lib/blog-utils';
 import { t, T } from '../../../lib/translations';
 
@@ -60,6 +62,9 @@ const totalPages = getTotalPages(filtered.length, perPage);
 const pageNum = Math.min(currentPage, totalPages);
 const pagePosts = paginate(filtered, pageNum, perPage);
 
+const upcomingEvents = selectUpcomingEvents(filtered);
+const searchIndex = buildPostSearchIndex(filtered);
+
 const translations = Astro.locals.translations ?? {};
 ---
 
@@ -90,6 +95,9 @@ const translations = Astro.locals.translations ?? {};
         totalPosts={filtered.length}
         basePath="/posts"
         translations={translations}
+        upcomingEvents={upcomingEvents}
+        searchIndex={searchIndex}
+        client:load
       />
     )}
   </div>

src/pages/posts/tag/[tag].astro

@@ -12,6 +12,8 @@ import {
   getTagsMap,
   resolvePostTagsInPost,
   getPostImageUrl,
+  buildPostSearchIndex,
+  selectUpcomingEvents,
 } from '../../../lib/blog-utils';
 import { t, T } from '../../../lib/translations';
 
@@ -72,6 +74,9 @@ const pagePosts = paginate(filtered, 1, perPage);
 
 const tagName = tags.find((t) => (t._slug ?? '') === tagSlug)?.name ?? tagSlug;
 
+const upcomingEvents = selectUpcomingEvents(filtered);
+const searchIndex = buildPostSearchIndex(filtered);
+
 const translations = Astro.locals.translations ?? {};
 ---
 
@@ -103,6 +108,9 @@ const translations = Astro.locals.translations ?? {};
         totalPosts={filtered.length}
         basePath="/posts"
         translations={translations}
+        upcomingEvents={upcomingEvents}
+        searchIndex={searchIndex}
+        client:load
       />
     )}
   </div>

src/pages/posts/tag/[tag]/page/[page].astro

@@ -12,6 +12,8 @@ import {
   getTagsMap,
   resolvePostTagsInPost,
   getPostImageUrl,
+  buildPostSearchIndex,
+  selectUpcomingEvents,
 } from '../../../../../lib/blog-utils';
 import { t, T } from '../../../../../lib/translations';
 
@@ -85,6 +87,9 @@ const pagePosts = paginate(filtered, pageNum, perPage);
 
 const tagName = tags.find((t) => (t._slug ?? '') === tagSlug)?.name ?? tagSlug;
 
+const upcomingEvents = selectUpcomingEvents(filtered);
+const searchIndex = buildPostSearchIndex(filtered);
+
 const translations = Astro.locals.translations ?? {};
 ---
 
@@ -116,6 +121,9 @@ const translations = Astro.locals.translations ?? {};
         totalPosts={filtered.length}
         basePath="/posts"
         translations={translations}
+        upcomingEvents={upcomingEvents}
+        searchIndex={searchIndex}
+        client:load
       />
     )}
   </div>