Add embedded Tantivy full-text content search

/api/search now finds files by CONTENT as well as by name: BM25-ranked
matches over extracted text (PDF, Office OOXML/ODF, plain text/code)
with typo-tolerant fuzzy terms and search-as-you-type prefix matching,
served from an embedded Tantivy index at {storage}/.search-index.

Pipeline (all off the request path, mirroring tree-etag + thumbnails):
- statement triggers on storage.files append to a durable dirty queue
  (storage.search_index_dirty) - every write surface (REST, WebDAV,
  NextCloud, WOPI, trash) is covered, crash-safe by construction
- ContentIndexWorker drains the queue on the maintenance pool, extracts
  text once per unique BLAKE3 blob (storage.blob_extracted_text cache:
  N copies = 1 extraction, renames/moves = 0 re-extraction) and applies
  batched single-writer Tantivy commits; queue rows are deleted only
  after the commit succeeds (at-least-once, idempotent upserts)
- the index is a derived artifact: a version-marker mismatch wipes and
  reseeds it from Postgres, which remains the single source of truth

SearchService merges content hits into the existing name search: hits
are hydrated through ONE SQL round-trip that re-applies user scope,
trash state and every active filter (a stale index id can never leak),
scored below name matches, and returned with a plain-text snippet and
a match_source field. Index failure or
OXICLOUD_ENABLE_CONTENT_SEARCH=false degrades to name-only search; a
discard-only janitor keeps the trigger-fed queue bounded while disabled.

The frontend renders the snippet under the file name in list view.

New dependencies: tantivy 0.26, zip 8.6 (deflate only), pdf-extract 0.10.

https://claude.ai/code/session_01Sc7F4xbo83YbFAQ4xEeDrX

src/application/services/search_service.rs

@@ -11,6 +11,7 @@ use crate::application::dtos::search_dto::{
     SearchCriteriaDto, SearchFileResultDto, SearchFolderResultDto, SearchResultsDto,
     SearchSuggestionItem, SearchSuggestionsDto,
 };
+use crate::application::ports::content_index_ports::{ContentHitDto, ContentIndexPort};
 use crate::application::ports::inbound::SearchUseCase;
 use crate::application::ports::storage_ports::FileReadPort;
 use crate::common::errors::Result;
@@ -44,6 +45,11 @@ pub struct SearchService {
     /// Repository for folder operations
     folder_repository: Arc<FolderDbRepository>,
 
+    /// Optional full-text content index (embedded Tantivy). When present,
+    /// query-bearing searches additionally surface files whose CONTENT
+    /// matches; hits are hydrated and re-filtered through SQL before use.
+    content_index: Option<Arc<dyn ContentIndexPort>>,
+
     /// Lock-free concurrent cache with automatic TTL and LRU eviction (moka).
     /// Values are `Arc<SearchResultsDto>` so cache insert/hit is a single
     /// atomic ref-count increment (~1 ns) instead of cloning thousands of Strings.
@@ -73,6 +79,35 @@ fn compute_relevance(name: &str, query_lower: &str) -> u32 {
     }
 }
 
+/// Max content-index candidates fetched per search. Hydration re-filters
+/// them in ONE SQL round-trip, so this bounds both index and DB work.
+const CONTENT_HITS_LIMIT: usize = 200;
+
+/// Map a BM25 score into the 10–45 relevance band, normalized against the
+/// best score of the result set. Deliberately below the weakest name match
+/// (contains = 50): a filename hit is more specific than a body mention.
+fn content_relevance(score: f32, max_score: f32) -> u32 {
+    if !score.is_finite() || max_score <= 0.0 {
+        return 10;
+    }
+    let ratio = (score / max_score).clamp(0.0, 1.0);
+    10 + (ratio * 35.0).round() as u32
+}
+
+/// Re-sort the merged file list with the same semantics the folder list
+/// uses. Only invoked when content hits were merged into a SQL-ordered page.
+fn sort_enriched_files(files: &mut [SearchFileResultDto], sort_by: &str) {
+    match sort_by {
+        "name" => files.sort_by_cached_key(|f| f.name.to_lowercase()),
+        "name_desc" => files.sort_by_cached_key(|f| Reverse(f.name.to_lowercase())),
+        "date" => files.sort_by_key(|f| f.modified_at),
+        "date_desc" => files.sort_by_key(|f| Reverse(f.modified_at)),
+        "size" => files.sort_by_key(|f| f.size),
+        "size_desc" => files.sort_by_key(|f| Reverse(f.size)),
+        _ => files.sort_by_key(|f| Reverse(f.relevance_score)),
+    }
+}
+
 /// Format bytes into a human-readable string (e.g. "2.5 MB").
 fn format_bytes(bytes: u64) -> String {
     const UNITS: &[&str] = &["B", "KB", "MB", "GB", "TB"];
@@ -115,6 +150,7 @@ impl SearchService {
     pub fn new(
         file_repository: Arc<FileBlobReadRepository>,
         folder_repository: Arc<FolderDbRepository>,
+        content_index: Option<Arc<dyn ContentIndexPort>>,
         cache_ttl: u64,
         max_cache_size: usize,
     ) -> Self {
@@ -126,6 +162,7 @@ impl SearchService {
         Self {
             file_repository,
             folder_repository,
+            content_index,
             search_cache,
         }
     }
@@ -176,6 +213,8 @@ impl SearchService {
             // responses on the NC surface can emit the same ETag
             // (`File::compute_etag`) as PROPFIND/GET would.
             blob_hash: file.content_hash.clone(),
+            snippet: None,
+            match_source: (!query_lower.is_empty() && relevance > 0).then(|| "name".to_string()),
         }
     }
 
@@ -201,6 +240,108 @@ impl SearchService {
         }
     }
 
+    /// Query the content index for files matching by CONTENT (when the index
+    /// is enabled). First page only — content hits have no stable
+    /// interleaving with SQL pagination beyond it, and page one is where
+    /// search UX lives. Index failures degrade to name-only results, never
+    /// to a failed search.
+    async fn lookup_content_hits(
+        &self,
+        criteria: &SearchCriteriaDto,
+        user_id: Uuid,
+    ) -> Vec<ContentHitDto> {
+        let Some(index) = &self.content_index else {
+            return Vec::new();
+        };
+        if criteria.offset != 0 {
+            return Vec::new();
+        }
+        let Some(query) = criteria
+            .name_contains
+            .as_deref()
+            .map(str::trim)
+            .filter(|q| q.len() >= 2)
+        else {
+            return Vec::new();
+        };
+
+        match index
+            .search_content(user_id, query, CONTENT_HITS_LIMIT)
+            .await
+        {
+            Ok(hits) => hits,
+            Err(e) => {
+                tracing::warn!("Content-index lookup failed — returning name-only results: {e}");
+                Vec::new()
+            }
+        }
+    }
+
+    /// Merge content-index hits into the name-search result page:
+    /// * files the name search already found just gain their `snippet`;
+    /// * content-only candidates are hydrated through SQL in one round-trip
+    ///   (re-applying user scope, trash state and every active filter — a
+    ///   stale index id silently drops out), enriched, scored into the
+    ///   content relevance band and appended;
+    /// * the merged page is re-sorted with the caller's `sort_by`.
+    ///
+    /// Returns how many files were added (callers bump their totals by it).
+    async fn merge_content_hits(
+        &self,
+        hits: Vec<ContentHitDto>,
+        enriched_files: &mut Vec<SearchFileResultDto>,
+        criteria: &SearchCriteriaDto,
+        user_id: Uuid,
+    ) -> Result<usize> {
+        if hits.is_empty() {
+            return Ok(0);
+        }
+
+        let mut by_id: std::collections::HashMap<&str, &ContentHitDto> =
+            hits.iter().map(|h| (h.file_id.as_str(), h)).collect();
+        for file in enriched_files.iter_mut() {
+            if let Some(hit) = by_id.remove(file.id.as_str()) {
+                file.snippet = hit.snippet.clone();
+            }
+        }
+        if by_id.is_empty() {
+            return Ok(0);
+        }
+
+        // Preserve the index's score order when collecting the leftovers.
+        let candidate_ids: Vec<String> = hits
+            .iter()
+            .filter(|h| by_id.contains_key(h.file_id.as_str()))
+            .map(|h| h.file_id.clone())
+            .collect();
+        let files = self
+            .file_repository
+            .fetch_files_by_ids_filtered(&candidate_ids, criteria, user_id)
+            .await?;
+        if files.is_empty() {
+            return Ok(0);
+        }
+
+        let max_score = hits.iter().map(|h| h.score).fold(0.0_f32, f32::max);
+        let mut added = 0usize;
+        for file in files {
+            let dto = FileDto::from(file);
+            let Some(hit) = by_id.get(dto.id.as_str()) else {
+                continue;
+            };
+            let mut enriched = Self::enrich_file(&dto, "");
+            enriched.relevance_score = content_relevance(hit.score, max_score);
+            enriched.snippet = hit.snippet.clone();
+            enriched.match_source = Some("content".to_string());
+            enriched_files.push(enriched);
+            added += 1;
+        }
+        if added > 0 {
+            sort_enriched_files(enriched_files, &criteria.sort_by);
+        }
+        Ok(added)
+    }
+
     /// Quick suggestions search — returns up to `limit` name suggestions
     /// matching the query. Pushes filtering, relevance sort and LIMIT to SQL
     /// so only a handful of rows cross the DB→app boundary.
@@ -305,6 +446,10 @@ impl SearchUseCase for SearchService {
         // Pre-compute once — avoids N heap allocations inside enrich_file/enrich_folder.
         let query_lower = query.to_lowercase();
 
+        // Content-index candidates (first page only). Feature-off or an
+        // index failure yields an empty set — the search stays name-only.
+        let content_hits = self.lookup_content_hits(&criteria, user_id).await;
+
         // For non-recursive searches, use efficient database-level pagination
         // This avoids loading all files into memory
         if !criteria.recursive {
@@ -316,7 +461,7 @@ impl SearchUseCase for SearchService {
 
             // Convert to DTOs and enrich with metadata
             let file_dtos: Vec<FileDto> = files.into_iter().map(FileDto::from).collect();
-            let enriched_files: Vec<SearchFileResultDto> = file_dtos
+            let mut enriched_files: Vec<SearchFileResultDto> = file_dtos
                 .iter()
                 .map(|f| Self::enrich_file(f, &query_lower))
                 .collect();
@@ -360,6 +505,12 @@ impl SearchUseCase for SearchService {
                 }
             }
 
+            // Blend in content-discovered files before the pagination math.
+            let added = self
+                .merge_content_hits(content_hits, &mut enriched_files, &criteria, user_id)
+                .await?;
+            let total_file_count = total_file_count + added;
+
             let folder_count = enriched_folders.len();
             let total_count = total_file_count + folder_count;
 
@@ -416,7 +567,7 @@ impl SearchUseCase for SearchService {
 
         // ── Convert to DTOs and enrich with server-computed metadata ──
         let file_dtos: Vec<FileDto> = found_files.into_iter().map(FileDto::from).collect();
-        let enriched_files: Vec<SearchFileResultDto> = file_dtos
+        let mut enriched_files: Vec<SearchFileResultDto> = file_dtos
             .iter()
             .map(|f| Self::enrich_file(f, &query_lower))
             .collect();
@@ -446,6 +597,12 @@ impl SearchUseCase for SearchService {
             }
         }
 
+        // Blend in content-discovered files before the pagination math.
+        let added = self
+            .merge_content_hits(content_hits, &mut enriched_files, &criteria, user_id)
+            .await?;
+        let total_file_count = total_file_count + added;
+
         // ── Pagination (folders first, then files) ──
         let folder_count = enriched_folders.len();
         let total_count = total_file_count + folder_count;
@@ -535,3 +692,60 @@ impl SearchService {
         SearchServiceStub
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn content_relevance_stays_below_name_contains_band() {
+        // Best hit of the set caps at 45 — always under contains (50).
+        assert_eq!(content_relevance(8.0, 8.0), 45);
+        assert_eq!(content_relevance(4.0, 8.0), 28);
+        // Degenerate inputs fall to the floor instead of panicking.
+        assert_eq!(content_relevance(1.0, 0.0), 10);
+        assert_eq!(content_relevance(f32::NAN, 8.0), 10);
+        assert!(content_relevance(0.0, 8.0) >= 10);
+    }
+
+    fn dto(name: &str, relevance: u32, size: u64, modified_at: u64) -> SearchFileResultDto {
+        SearchFileResultDto {
+            id: name.to_string(),
+            name: name.to_string(),
+            path: format!("/{name}"),
+            size,
+            mime_type: "text/plain".to_string(),
+            folder_id: None,
+            created_at: 0,
+            modified_at,
+            relevance_score: relevance,
+            size_formatted: String::new(),
+            icon_class: String::new(),
+            icon_special_class: String::new(),
+            category: String::new(),
+            blob_hash: String::new(),
+            snippet: None,
+            match_source: None,
+        }
+    }
+
+    #[test]
+    fn merged_files_resort_by_relevance_and_by_column() {
+        let mut files = vec![
+            dto("b-content.txt", 30, 10, 200),
+            dto("a-name.txt", 80, 99, 100),
+        ];
+        sort_enriched_files(&mut files, "relevance");
+        assert_eq!(
+            files[0].name, "a-name.txt",
+            "name match must outrank content match"
+        );
+
+        sort_enriched_files(&mut files, "size_desc");
+        assert_eq!(files[0].name, "a-name.txt");
+        sort_enriched_files(&mut files, "date");
+        assert_eq!(files[0].name, "a-name.txt");
+        sort_enriched_files(&mut files, "name_desc");
+        assert_eq!(files[0].name, "b-content.txt");
+    }
+}