Search: a word with a leading ^ matches at a word's start only

"^zed" finds "Zed Dead", "The_Zed_Files", not "Facialized": a regex on
release_texts, (^|[^[:alnum:]]) before the word, which the trigram index
serves (homelab: 551 texts for ^zed against 6,606 for zed, 35 ms warm).
Words without ^ match anywhere as before; the search box says so.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/services/search_service.ts

@@ -85,6 +85,19 @@ function contains(word: string): string {
   return `%${word.replace(/[\\%_]/g, (c) => `\\${c}`)}%`
 }
 
+/**
+ * A search word's condition on release_texts: anywhere in a text (ILIKE), or with a leading "^" at a word's start, the
+ * text's or after a character that's no letter or digit ("^zed" finds "Zed.Dead", "The_Zed", not "Facialized"). Both
+ * use the trigram index.
+ */
+function wordMatch(word: string): { sql: string; binding: string } {
+  if (word.startsWith('^') && word.length > 1) {
+    const rest = word.slice(1).replace(/[\\^$.|?*+()[\]{}]/g, (c) => `\\${c}`)
+    return { sql: 't.text ~* ?', binding: `(^|[^[:alnum:]])${rest}` }
+  }
+  return { sql: 't.text ILIKE ?', binding: contains(word) }
+}
+
 /** Searching and browsing the catalog, for the web interface and Newznab. */
 class SearchService {
   async search(params: SearchParams) {
@@ -93,10 +106,12 @@ class SearchService {
     if (!params.judged) where.push('NOT EXISTS (SELECT 1 FROM release_verdicts v WHERE v.release_id = r.id)')
     const bindings: unknown[] = []
     // Every word in one of the release's texts (its name, the names the prober found inside; release_texts, by its
-    // trigram index, which yields ids: never an OR across the two tables); "The.Block.AU" and "the block au" alike.
+    // trigram index, which yields ids: never an OR across the two tables); "The.Block.AU" and "the block au" alike;
+    // "^zed" only at a word's start.
     for (const word of (params.q ?? '').split(/[\s._-]+/).filter(Boolean).slice(0, 8)) {
-      where.push('r.id IN (SELECT t.release_id FROM release_texts t WHERE t.text ILIKE ?)')
-      bindings.push(contains(word))
+      const match = wordMatch(word)
+      where.push(`r.id IN (SELECT t.release_id FROM release_texts t WHERE ${match.sql})`)
+      bindings.push(match.binding)
     }
     if (params.readable) where.push('(r.readable OR r.inner_name IS NOT NULL)')
     if (params.complete) where.push('r.complete')