initial commit

Co-authored-by: Copilot <copilot@github.com>

specs/search.allium

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+-- allium: 1
+-- bDS Full-Text Search
+-- Scope: core (Wave 1 — in-app full-text search with Snowball stemmers)
+-- Distilled from: src/main/engine/PostEngine.ts (FTS methods),
+--   MediaEngine.ts (FTS methods), stemmer.ts
+
+use "./post.allium" as post
+use "./media.allium" as media
+
+surface SearchControlSurface {
+    facing _: SearchOperator
+
+    provides:
+        SearchPostsRequested(query, filters)
+        SearchMediaRequested(query)
+}
+
+surface SearchIndexRuntimeSurface {
+    facing _: SearchRuntime
+
+    provides:
+        SearchIndexUpdated(post)
+        SearchIndexUpdated(media)
+}
+
+value StemmerLanguage {
+    -- Snowball stemmers for 24 languages
+    -- ISO 639-1 to Snowball mapping
+    -- Applied to both indexing and query processing
+    code: String
+}
+
+surface StemmerLanguageSurface {
+    context language: StemmerLanguage
+
+    exposes:
+        language.code
+}
+
+entity PostSearchIndex {
+    -- Full-text index projection
+    -- Indexed fields: title, excerpt, content, tags, categories
+    -- Plus all translation titles, excerpts, and content
+    post: post/Post
+    stemmed_content: String
+}
+
+entity MediaSearchIndex {
+    -- Full-text index projection
+    -- Indexed fields: title, alt, caption, original_name, tags
+    -- Plus all translation titles, alts, and captions
+    media: media/Media
+    stemmed_content: String
+}
+
+invariant CrossLanguageStemming {
+    -- Search index uses Snowball stemmer matched to content language
+    -- A post in German is stemmed with the German stemmer
+    -- Translations are stemmed with their respective language stemmers
+    -- Query-time stemming matches the index language
+}
+
+rule SearchPosts {
+    when: SearchPostsRequested(query, filters)
+    -- Full-text search with optional filters:
+    --   status, tags, categories, language, missingTranslationLanguage,
+    --   year, month, date range (from/to)
+    -- Returns paginated results with total count
+    let stemmed_query = stem(query, detect_language(query))
+    let matched = search_fts(PostSearchIndex, stemmed_query, filters)
+    ensures: SearchResults(
+        posts: matched,
+        total: matched.count,
+        offset: filters.offset,
+        limit: filters.limit
+    )
+}
+
+rule SearchMedia {
+    when: SearchMediaRequested(query)
+    let stemmed_query = stem(query, detect_language(query))
+    let matched = search_fts(MediaSearchIndex, stemmed_query)
+    ensures: SearchResults(
+        media: matched
+    )
+}
+
+rule IndexPost {
+    when: SearchIndexUpdated(post)
+    -- Stems: title + excerpt + content + tags + categories
+    -- Plus all translations' title + excerpt + content
+    let all_text = concat_post_text(post)
+        -- Concatenates: post.title, post.excerpt, post.content,
+        -- join(post.tags, " "), join(post.categories, " "),
+        -- and all translations' title, excerpt, content
+    let index_entry = PostSearchIndex{post: post}
+    ensures:
+        if exists index_entry:
+            index_entry.stemmed_content = stem(all_text)
+        else:
+            PostSearchIndex.created(post: post, stemmed_content: stem(all_text))
+}
+
+rule IndexMedia {
+    when: SearchIndexUpdated(media)
+    -- Stems: title + alt + caption + original_name + tags
+    -- Plus all translations' title, alt, caption
+    let all_text = concat_media_text(media)
+        -- Concatenates: media.title, media.alt, media.caption,
+        -- media.original_name, join(media.tags, " "),
+        -- and all translations' title, alt, caption
+    let index_entry = MediaSearchIndex{media: media}
+    ensures:
+        if exists index_entry:
+            index_entry.stemmed_content = stem(all_text)
+        else:
+            MediaSearchIndex.created(media: media, stemmed_content: stem(all_text))
+}