feat(search): add SQLite FTS5 full-text search index for recipes

Introduce a new RecipeFTSIndex class that provides fast prefix-based search across recipe fields (title, tags, LoRA names/models, prompts) using SQLite's FTS5 extension. The implementation supports sub-100ms search times for large datasets (20k+ recipes) and includes asynchronous indexing, incremental updates, and comprehensive unit tests.

tests/services/test_recipe_fts_index.py

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+"""Tests for RecipeFTSIndex service."""
+
+import os
+import pytest
+import tempfile
+import time
+from pathlib import Path
+
+from py.services.recipe_fts_index import RecipeFTSIndex
+
+
+@pytest.fixture
+def temp_db_path(tmp_path):
+    """Create a temporary database path for testing."""
+    return str(tmp_path / "test_recipe_fts.sqlite")
+
+
+@pytest.fixture
+def fts_index(temp_db_path):
+    """Create a RecipeFTSIndex instance with a temporary database."""
+    return RecipeFTSIndex(db_path=temp_db_path)
+
+
+@pytest.fixture
+def sample_recipes():
+    """Sample recipe data for testing."""
+    return [
+        {
+            'id': 'recipe-1',
+            'title': 'Beautiful Sunset Landscape',
+            'tags': ['landscape', 'sunset', 'photography'],
+            'loras': [
+                {'file_name': 'sunset_lora', 'modelName': 'Sunset Style'},
+                {'file_name': 'landscape_v2', 'modelName': 'Landscape Enhancer'},
+            ],
+            'gen_params': {
+                'prompt': '1girl, sunset, beach, golden hour',
+                'negative_prompt': 'ugly, blurry, low quality',
+            },
+        },
+        {
+            'id': 'recipe-2',
+            'title': 'Anime Portrait Style',
+            'tags': ['anime', 'portrait', 'character'],
+            'loras': [
+                {'file_name': 'anime_style_v3', 'modelName': 'Anime Master'},
+            ],
+            'gen_params': {
+                'prompt': '1girl, anime style, beautiful eyes, detailed hair',
+                'negative_prompt': 'worst quality, bad anatomy',
+            },
+        },
+        {
+            'id': 'recipe-3',
+            'title': 'Cyberpunk City Night',
+            'tags': ['cyberpunk', 'city', 'night'],
+            'loras': [
+                {'file_name': 'cyberpunk_neon', 'modelName': 'Neon Lights'},
+                {'file_name': 'city_streets', 'modelName': 'Urban Environments'},
+            ],
+            'gen_params': {
+                'prompt': 'cyberpunk city, neon lights, rain, night time',
+                'negative_prompt': 'daylight, sunny',
+            },
+        },
+    ]
+
+
+class TestRecipeFTSIndexInitialization:
+    """Tests for FTS index initialization."""
+
+    def test_initialize_creates_database(self, fts_index, temp_db_path):
+        """Test that initialize creates the database file."""
+        fts_index.initialize()
+        assert os.path.exists(temp_db_path)
+
+    def test_initialize_is_idempotent(self, fts_index):
+        """Test that calling initialize multiple times is safe."""
+        fts_index.initialize()
+        fts_index.initialize()
+        fts_index.initialize()
+        assert fts_index._schema_initialized
+
+    def test_is_ready_false_before_build(self, fts_index):
+        """Test that is_ready returns False before index is built."""
+        assert not fts_index.is_ready()
+
+    def test_get_database_path(self, fts_index, temp_db_path):
+        """Test that get_database_path returns the correct path."""
+        assert fts_index.get_database_path() == temp_db_path
+
+
+class TestRecipeFTSIndexBuild:
+    """Tests for FTS index building."""
+
+    def test_build_index_creates_ready_index(self, fts_index, sample_recipes):
+        """Test that build_index makes the index ready."""
+        fts_index.build_index(sample_recipes)
+        assert fts_index.is_ready()
+
+    def test_build_index_counts_recipes(self, fts_index, sample_recipes):
+        """Test that build_index indexes all recipes."""
+        fts_index.build_index(sample_recipes)
+        assert fts_index.get_indexed_count() == len(sample_recipes)
+
+    def test_build_index_empty_list(self, fts_index):
+        """Test building index with empty recipe list."""
+        fts_index.build_index([])
+        assert fts_index.is_ready()
+        assert fts_index.get_indexed_count() == 0
+
+    def test_build_index_handles_recipes_without_id(self, fts_index):
+        """Test that recipes without ID are skipped."""
+        recipes = [
+            {'title': 'No ID Recipe', 'tags': ['test']},
+            {'id': 'valid-id', 'title': 'Valid Recipe', 'tags': ['test']},
+        ]
+        fts_index.build_index(recipes)
+        assert fts_index.get_indexed_count() == 1
+
+    def test_build_index_handles_missing_fields(self, fts_index):
+        """Test that missing optional fields are handled gracefully."""
+        recipes = [
+            {'id': 'minimal', 'title': 'Minimal Recipe'},
+        ]
+        fts_index.build_index(recipes)
+        assert fts_index.is_ready()
+        assert fts_index.get_indexed_count() == 1
+
+
+class TestRecipeFTSIndexSearch:
+    """Tests for FTS search functionality."""
+
+    def test_search_by_title(self, fts_index, sample_recipes):
+        """Test searching by recipe title."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('sunset')
+        assert 'recipe-1' in results
+
+        results = fts_index.search('anime')
+        assert 'recipe-2' in results
+
+    def test_search_by_tags(self, fts_index, sample_recipes):
+        """Test searching by recipe tags."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('landscape')
+        assert 'recipe-1' in results
+
+        results = fts_index.search('cyberpunk')
+        assert 'recipe-3' in results
+
+    def test_search_by_lora_name(self, fts_index, sample_recipes):
+        """Test searching by LoRA file name."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('anime_style')
+        assert 'recipe-2' in results
+
+        results = fts_index.search('cyberpunk_neon')
+        assert 'recipe-3' in results
+
+    def test_search_by_lora_model_name(self, fts_index, sample_recipes):
+        """Test searching by LoRA model name."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('Anime Master')
+        assert 'recipe-2' in results
+
+    def test_search_by_prompt(self, fts_index, sample_recipes):
+        """Test searching by prompt content."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('golden hour')
+        assert 'recipe-1' in results
+
+        results = fts_index.search('neon lights')
+        assert 'recipe-3' in results
+
+    def test_search_prefix_matching(self, fts_index, sample_recipes):
+        """Test that prefix matching works."""
+        fts_index.build_index(sample_recipes)
+
+        # 'sun' should match 'sunset'
+        results = fts_index.search('sun')
+        assert 'recipe-1' in results
+
+        # 'ani' should match 'anime'
+        results = fts_index.search('ani')
+        assert 'recipe-2' in results
+
+    def test_search_multiple_words(self, fts_index, sample_recipes):
+        """Test searching with multiple words (AND logic)."""
+        fts_index.build_index(sample_recipes)
+
+        # Both words must match
+        results = fts_index.search('city night')
+        assert 'recipe-3' in results
+
+    def test_search_case_insensitive(self, fts_index, sample_recipes):
+        """Test that search is case-insensitive."""
+        fts_index.build_index(sample_recipes)
+
+        results_lower = fts_index.search('sunset')
+        results_upper = fts_index.search('SUNSET')
+        results_mixed = fts_index.search('SuNsEt')
+
+        assert results_lower == results_upper == results_mixed
+
+    def test_search_no_results(self, fts_index, sample_recipes):
+        """Test search with no matching results."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('nonexistent')
+        assert len(results) == 0
+
+    def test_search_empty_query(self, fts_index, sample_recipes):
+        """Test search with empty query."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('')
+        assert len(results) == 0
+
+        results = fts_index.search('   ')
+        assert len(results) == 0
+
+    def test_search_not_ready_returns_empty(self, fts_index):
+        """Test that search returns empty set when index not ready."""
+        results = fts_index.search('test')
+        assert len(results) == 0
+
+
+class TestRecipeFTSIndexFieldRestriction:
+    """Tests for field-specific search."""
+
+    def test_search_title_only(self, fts_index, sample_recipes):
+        """Test searching only in title field."""
+        fts_index.build_index(sample_recipes)
+
+        # 'portrait' appears in title of recipe-2
+        results = fts_index.search('portrait', fields={'title'})
+        assert 'recipe-2' in results
+
+    def test_search_tags_only(self, fts_index, sample_recipes):
+        """Test searching only in tags field."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('photography', fields={'tags'})
+        assert 'recipe-1' in results
+
+    def test_search_lora_name_only(self, fts_index, sample_recipes):
+        """Test searching only in lora_name field."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('sunset_lora', fields={'lora_name'})
+        assert 'recipe-1' in results
+
+    def test_search_prompt_only(self, fts_index, sample_recipes):
+        """Test searching only in prompt field."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('golden hour', fields={'prompt'})
+        assert 'recipe-1' in results
+
+        # 'ugly' appears in negative_prompt
+        results = fts_index.search('ugly', fields={'prompt'})
+        assert 'recipe-1' in results
+
+    def test_search_multiple_fields(self, fts_index, sample_recipes):
+        """Test searching in multiple fields."""
+        fts_index.build_index(sample_recipes)
+
+        results = fts_index.search('sunset', fields={'title', 'tags'})
+        assert 'recipe-1' in results
+
+
+class TestRecipeFTSIndexIncrementalOperations:
+    """Tests for incremental add/remove/update operations."""
+
+    def test_add_recipe(self, fts_index, sample_recipes):
+        """Test adding a single recipe to the index."""
+        fts_index.build_index(sample_recipes)
+        initial_count = fts_index.get_indexed_count()
+
+        new_recipe = {
+            'id': 'recipe-new',
+            'title': 'New Fantasy Scene',
+            'tags': ['fantasy', 'magic'],
+            'loras': [{'file_name': 'fantasy_lora', 'modelName': 'Fantasy Style'}],
+            'gen_params': {'prompt': 'magical forest, wizard'},
+        }
+        fts_index.add_recipe(new_recipe)
+
+        assert fts_index.get_indexed_count() == initial_count + 1
+        assert 'recipe-new' in fts_index.search('fantasy')
+
+    def test_remove_recipe(self, fts_index, sample_recipes):
+        """Test removing a recipe from the index."""
+        fts_index.build_index(sample_recipes)
+        initial_count = fts_index.get_indexed_count()
+
+        # Verify recipe-1 is searchable
+        assert 'recipe-1' in fts_index.search('sunset')
+
+        # Remove it
+        fts_index.remove_recipe('recipe-1')
+
+        # Verify it's gone
+        assert fts_index.get_indexed_count() == initial_count - 1
+        assert 'recipe-1' not in fts_index.search('sunset')
+
+    def test_update_recipe(self, fts_index, sample_recipes):
+        """Test updating a recipe in the index."""
+        fts_index.build_index(sample_recipes)
+
+        # Update recipe-1 title
+        updated_recipe = {
+            'id': 'recipe-1',
+            'title': 'Tropical Beach Paradise',  # Changed from 'Beautiful Sunset Landscape'
+            'tags': ['beach', 'tropical'],  # Changed tags
+            'loras': sample_recipes[0]['loras'],
+            'gen_params': sample_recipes[0]['gen_params'],
+        }
+        fts_index.update_recipe(updated_recipe)
+
+        # Old title should not match
+        results = fts_index.search('sunset', fields={'title'})
+        assert 'recipe-1' not in results
+
+        # New title should match
+        results = fts_index.search('tropical', fields={'title'})
+        assert 'recipe-1' in results
+
+    def test_add_recipe_not_ready(self, fts_index):
+        """Test that add_recipe returns False when index not ready."""
+        recipe = {'id': 'test', 'title': 'Test'}
+        result = fts_index.add_recipe(recipe)
+        assert result is False
+
+    def test_remove_recipe_not_ready(self, fts_index):
+        """Test that remove_recipe returns False when index not ready."""
+        result = fts_index.remove_recipe('test')
+        assert result is False
+
+
+class TestRecipeFTSIndexClear:
+    """Tests for clearing the FTS index."""
+
+    def test_clear_index(self, fts_index, sample_recipes):
+        """Test clearing all data from the index."""
+        fts_index.build_index(sample_recipes)
+        assert fts_index.get_indexed_count() > 0
+
+        fts_index.clear()
+        assert fts_index.get_indexed_count() == 0
+        assert not fts_index.is_ready()
+
+
+class TestRecipeFTSIndexSpecialCharacters:
+    """Tests for handling special characters in search."""
+
+    def test_search_with_special_characters(self, fts_index):
+        """Test that special characters are handled safely."""
+        recipes = [
+            {'id': 'r1', 'title': 'Test (with) parentheses', 'tags': []},
+            {'id': 'r2', 'title': 'Test "with" quotes', 'tags': []},
+            {'id': 'r3', 'title': 'Test:with:colons', 'tags': []},
+        ]
+        fts_index.build_index(recipes)
+
+        # These should not crash
+        results = fts_index.search('(with)')
+        results = fts_index.search('"with"')
+        results = fts_index.search(':with:')
+
+        # Basic word should still match
+        results = fts_index.search('test')
+        assert len(results) == 3
+
+    def test_search_unicode_characters(self, fts_index):
+        """Test searching with unicode characters."""
+        recipes = [
+            {'id': 'r1', 'title': '日本語テスト', 'tags': ['anime']},
+            {'id': 'r2', 'title': 'Émilie résumé café', 'tags': ['french']},
+        ]
+        fts_index.build_index(recipes)
+
+        # Unicode search
+        results = fts_index.search('日本')
+        assert 'r1' in results
+
+        # Diacritics (depends on tokenizer settings)
+        results = fts_index.search('cafe')  # Should match café due to remove_diacritics
+        # Note: Result depends on FTS5 configuration
+
+
+class TestRecipeFTSIndexPerformance:
+    """Basic performance tests."""
+
+    def test_build_large_index(self, fts_index):
+        """Test building index with many recipes."""
+        recipes = [
+            {
+                'id': f'recipe-{i}',
+                'title': f'Recipe Title {i} with words like sunset landscape anime cyberpunk',
+                'tags': ['tag1', 'tag2', 'tag3'],
+                'loras': [{'file_name': f'lora_{i}', 'modelName': f'Model {i}'}],
+                'gen_params': {'prompt': f'test prompt {i}', 'negative_prompt': 'bad'},
+            }
+            for i in range(1000)
+        ]
+
+        start_time = time.time()
+        fts_index.build_index(recipes)
+        build_time = time.time() - start_time
+
+        assert fts_index.is_ready()
+        assert fts_index.get_indexed_count() == 1000
+        # Build should complete reasonably fast (under 5 seconds)
+        assert build_time < 5.0
+
+    def test_search_large_index(self, fts_index):
+        """Test searching a large index."""
+        recipes = [
+            {
+                'id': f'recipe-{i}',
+                'title': f'Recipe Title {i}',
+                'tags': ['common_tag'],
+                'loras': [],
+                'gen_params': {},
+            }
+            for i in range(1000)
+        ]
+        fts_index.build_index(recipes)
+
+        start_time = time.time()
+        results = fts_index.search('common_tag')
+        search_time = time.time() - start_time
+
+        assert len(results) == 1000
+        # Search should be very fast (under 100ms)
+        assert search_time < 0.1