1bb6b2e9f3
spawn_indexer builds LineIndex from mmap snapshot but IndexCache::save() re-opened the file to compute the hash. If the file changed between those two steps, the cached index would be stored under the wrong hash. - Add IndexCache::save_with_hash() that computes hash from in-memory data - Add compute_data_hash() public function (same algorithm as compute_file_hash) - Update spawn_indexer, FileReader::save_cache, and test callers