Enha (rag): async writes

rag/embedder.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"os"
 	"sync"
+	"time"
 
 	"github.com/sugarme/tokenizer"
 	"github.com/sugarme/tokenizer/pretrained"
@@ -33,8 +34,10 @@ type APIEmbedder struct {
 func NewAPIEmbedder(l *slog.Logger, cfg *config.Config) *APIEmbedder {
 	return &APIEmbedder{
 		logger: l,
-		client: &http.Client{},
+		client: &http.Client{
-		cfg:    cfg,
+			Timeout: 30 * time.Second,
+		},
+		cfg: cfg,
 	}
 }
 

rag/rag.go

@@ -1,6 +1,7 @@
 package rag
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"gf-lt/config"
@@ -9,6 +10,7 @@ import (
 	"log/slog"
 	"path"
 	"regexp"
+	"runtime"
 	"sort"
 	"strings"
 	"sync"
@@ -17,9 +19,14 @@ import (
 	"github.com/neurosnap/sentences/english"
 )
 
+const (
+	// batchTimeout is the maximum time allowed for embedding a single batch
+	batchTimeout = 2 * time.Minute
+)
+
 var (
 	// Status messages for TUI integration
-	LongJobStatusCh     = make(chan string, 10) // Increased buffer size to prevent blocking
+	LongJobStatusCh     = make(chan string, 100) // Increased buffer size for parallel batch updates
 	FinishedRAGStatus   = "finished loading RAG file; press Enter"
 	LoadedFileRAGStatus = "loaded file"
 	ErrRAGStatus        = "some error occurred; failed to transfer data to vector db"
@@ -31,12 +38,38 @@ type RAG struct {
 	cfg         *config.Config
 	embedder    Embedder
 	storage     *VectorStorage
-	mu          sync.Mutex
+	mu          sync.RWMutex
+	idleMu      sync.Mutex
 	fallbackMsg string
 	idleTimer   *time.Timer
 	idleTimeout time.Duration
 }
 
+// batchTask represents a single batch to be embedded
+type batchTask struct {
+	batchIndex   int
+	paragraphs   []string
+	filename     string
+	totalBatches int
+}
+
+// batchResult represents the result of embedding a batch
+type batchResult struct {
+	batchIndex int
+	embeddings [][]float32
+	paragraphs []string
+	filename   string
+}
+
+// sendStatusNonBlocking sends a status message without blocking
+func (r *RAG) sendStatusNonBlocking(status string) {
+	select {
+	case LongJobStatusCh <- status:
+	default:
+		r.logger.Warn("LongJobStatusCh channel is full or closed, dropping status message", "message", status)
+	}
+}
+
 func New(l *slog.Logger, s storage.FullRepo, cfg *config.Config) (*RAG, error) {
 	var embedder Embedder
 	var fallbackMsg string
@@ -142,18 +175,22 @@ func sanitizeFTSQuery(query string) string {
 }
 
 func (r *RAG) LoadRAG(fpath string) error {
+	return r.LoadRAGWithContext(context.Background(), fpath)
+}
+
+func (r *RAG) LoadRAGWithContext(ctx context.Context, fpath string) error {
 	r.mu.Lock()
 	defer r.mu.Unlock()
+
 	fileText, err := ExtractText(fpath)
 	if err != nil {
 		return err
 	}
 	r.logger.Debug("rag: loaded file", "fp", fpath)
-	select {
+
-	case LongJobStatusCh <- LoadedFileRAGStatus:
+	// Send initial status (non-blocking with retry)
-	default:
+	r.sendStatusNonBlocking(LoadedFileRAGStatus)
-		r.logger.Warn("LongJobStatusCh channel is full or closed, dropping status message", "message", LoadedFileRAGStatus)
+
-	}
 	tokenizer, err := english.NewSentenceTokenizer(nil)
 	if err != nil {
 		return err
@@ -163,6 +200,7 @@ func (r *RAG) LoadRAG(fpath string) error {
 	for i, s := range sentences {
 		sents[i] = s.Text
 	}
+
 	// Create chunks with overlap
 	paragraphs := createChunks(sents, r.cfg.RAGWordLimit, r.cfg.RAGOverlapWords)
 	// Adjust batch size if needed
@@ -172,76 +210,332 @@ func (r *RAG) LoadRAG(fpath string) error {
 	if len(paragraphs) == 0 {
 		return errors.New("no valid paragraphs found in file")
 	}
-	// Process paragraphs in batches synchronously
+
-	batchCount := 0
+	totalBatches := (len(paragraphs) + r.cfg.RAGBatchSize - 1) / r.cfg.RAGBatchSize
-	for i := 0; i < len(paragraphs); i += r.cfg.RAGBatchSize {
+	r.logger.Debug("starting parallel embedding", "total_batches", totalBatches, "batch_size", r.cfg.RAGBatchSize)
-		end := i + r.cfg.RAGBatchSize
+
-		if end > len(paragraphs) {
+	// Determine concurrency level
-			end = len(paragraphs)
+	concurrency := runtime.NumCPU()
-		}
+	if concurrency > totalBatches {
-		batch := paragraphs[i:end]
+		concurrency = totalBatches
-		batchCount++
+	}
-		// Filter empty paragraphs
+	if concurrency < 1 {
-		nonEmptyBatch := make([]string, 0, len(batch))
+		concurrency = 1
-		for _, p := range batch {
+	}
-			if strings.TrimSpace(p) != "" {
+	// If using ONNX embedder, limit concurrency to 1 due to mutex serialization
-				nonEmptyBatch = append(nonEmptyBatch, strings.TrimSpace(p))
+	isONNX := false
+	if _, isONNX = r.embedder.(*ONNXEmbedder); isONNX {
+		concurrency = 1
+	}
+	embedderType := "API"
+	if isONNX {
+		embedderType = "ONNX"
+	}
+	r.logger.Debug("parallel embedding setup",
+		"total_batches", totalBatches,
+		"concurrency", concurrency,
+		"embedder", embedderType,
+		"batch_size", r.cfg.RAGBatchSize)
+
+	// Create context with timeout (30 minutes) and cancellation for error handling
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Minute)
+	defer cancel()
+
+	// Channels for task distribution and results
+	taskCh := make(chan batchTask, totalBatches)
+	resultCh := make(chan batchResult, totalBatches)
+	errorCh := make(chan error, totalBatches)
+
+	// Start worker goroutines
+	var wg sync.WaitGroup
+	for w := 0; w < concurrency; w++ {
+		wg.Add(1)
+		go r.embeddingWorker(ctx, w, taskCh, resultCh, errorCh, &wg)
+	}
+
+	// Close task channel after all tasks are sent (by separate goroutine)
+	go func() {
+		// Ensure task channel is closed when this goroutine exits
+		defer close(taskCh)
+		r.logger.Debug("task distributor started", "total_batches", totalBatches)
+
+		for i := 0; i < totalBatches; i++ {
+			start := i * r.cfg.RAGBatchSize
+			end := start + r.cfg.RAGBatchSize
+			if end > len(paragraphs) {
+				end = len(paragraphs)
+			}
+			batch := paragraphs[start:end]
+
+			// Filter empty paragraphs
+			nonEmptyBatch := make([]string, 0, len(batch))
+			for _, p := range batch {
+				if strings.TrimSpace(p) != "" {
+					nonEmptyBatch = append(nonEmptyBatch, strings.TrimSpace(p))
+				}
+			}
+
+			task := batchTask{
+				batchIndex:   i,
+				paragraphs:   nonEmptyBatch,
+				filename:     path.Base(fpath),
+				totalBatches: totalBatches,
+			}
+
+			select {
+			case taskCh <- task:
+				r.logger.Debug("task distributor sent batch", "batch", i, "paragraphs", len(nonEmptyBatch))
+			case <-ctx.Done():
+				r.logger.Debug("task distributor cancelled", "batches_sent", i+1, "total_batches", totalBatches)
+				return
 			}
 		}
-		if len(nonEmptyBatch) == 0 {
+		r.logger.Debug("task distributor finished", "batches_sent", totalBatches)
+	}()
+
+	// Wait for workers to finish and close result channel
+	go func() {
+		wg.Wait()
+		close(resultCh)
+	}()
+
+	// Process results in order and write to database
+	nextExpectedBatch := 0
+	resultsBuffer := make(map[int]batchResult)
+	filename := path.Base(fpath)
+	batchesProcessed := 0
+
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+
+		case err := <-errorCh:
+			// First error from any worker, cancel everything
+			cancel()
+			r.logger.Error("embedding worker failed", "error", err)
+			r.sendStatusNonBlocking(ErrRAGStatus)
+			return fmt.Errorf("embedding failed: %w", err)
+
+		case result, ok := <-resultCh:
+			if !ok {
+				// All results processed
+				resultCh = nil
+				r.logger.Debug("result channel closed", "batches_processed", batchesProcessed, "total_batches", totalBatches)
+				continue
+			}
+
+			// Store result in buffer
+			resultsBuffer[result.batchIndex] = result
+
+			// Process buffered results in order
+			for {
+				if res, exists := resultsBuffer[nextExpectedBatch]; exists {
+					// Write this batch to database
+					if err := r.writeBatchToStorage(ctx, res, filename); err != nil {
+						cancel()
+						return err
+					}
+
+					batchesProcessed++
+					// Send progress update
+					statusMsg := fmt.Sprintf("processed batch %d/%d", batchesProcessed, totalBatches)
+					r.sendStatusNonBlocking(statusMsg)
+
+					delete(resultsBuffer, nextExpectedBatch)
+					nextExpectedBatch++
+				} else {
+					break
+				}
+			}
+
+		default:
+			// No channels ready, check for deadlock conditions
+			if resultCh == nil && nextExpectedBatch < totalBatches {
+				// Missing batch results after result channel closed
+				r.logger.Error("missing batch results",
+					"expected", totalBatches,
+					"received", nextExpectedBatch,
+					"missing", totalBatches-nextExpectedBatch)
+
+				// Wait a short time for any delayed errors, then cancel
+				select {
+				case <-time.After(5 * time.Second):
+					cancel()
+					return fmt.Errorf("missing batch results: expected %d, got %d", totalBatches, nextExpectedBatch)
+				case <-ctx.Done():
+					return ctx.Err()
+				case err := <-errorCh:
+					cancel()
+					r.logger.Error("embedding worker failed after result channel closed", "error", err)
+					r.sendStatusNonBlocking(ErrRAGStatus)
+					return fmt.Errorf("embedding failed: %w", err)
+				}
+			}
+			// If we reach here, no deadlock yet, just busy loop prevention
+			time.Sleep(100 * time.Millisecond)
+		}
+
+		// Check if we're done
+		if resultCh == nil && nextExpectedBatch >= totalBatches {
+			r.logger.Debug("all batches processed successfully", "total", totalBatches)
+			break
+		}
+	}
+
+	r.logger.Debug("finished writing vectors", "batches", batchesProcessed)
+	r.resetIdleTimer()
+	r.sendStatusNonBlocking(FinishedRAGStatus)
+	return nil
+}
+
+// embeddingWorker processes batch embedding tasks
+func (r *RAG) embeddingWorker(ctx context.Context, workerID int, taskCh <-chan batchTask, resultCh chan<- batchResult, errorCh chan<- error, wg *sync.WaitGroup) {
+	defer wg.Done()
+	r.logger.Debug("embedding worker started", "worker", workerID)
+
+	// Panic recovery to ensure worker doesn't crash silently
+	defer func() {
+		if rec := recover(); rec != nil {
+			r.logger.Error("embedding worker panicked", "worker", workerID, "panic", rec)
+			// Try to send error, but don't block if channel is full
+			select {
+			case errorCh <- fmt.Errorf("worker %d panicked: %v", workerID, rec):
+			default:
+				r.logger.Warn("error channel full, dropping panic error", "worker", workerID)
+			}
+		}
+	}()
+
+	for task := range taskCh {
+		select {
+		case <-ctx.Done():
+			r.logger.Debug("embedding worker cancelled", "worker", workerID)
+			return
+		default:
+		}
+		r.logger.Debug("worker processing batch", "worker", workerID, "batch", task.batchIndex, "paragraphs", len(task.paragraphs), "total_batches", task.totalBatches)
+
+		// Skip empty batches
+		if len(task.paragraphs) == 0 {
+			select {
+			case resultCh <- batchResult{
+				batchIndex: task.batchIndex,
+				embeddings: nil,
+				paragraphs: nil,
+				filename:   task.filename,
+			}:
+			case <-ctx.Done():
+				r.logger.Debug("embedding worker cancelled while sending empty batch", "worker", workerID)
+				return
+			}
+			r.logger.Debug("worker sent empty batch", "worker", workerID, "batch", task.batchIndex)
 			continue
 		}
-		// Embed the batch
+
-		embeddings, err := r.embedder.EmbedSlice(nonEmptyBatch)
+		// Embed with retry for API embedder
+		embeddings, err := r.embedWithRetry(ctx, task.paragraphs, 3)
 		if err != nil {
-			r.logger.Error("failed to embed batch", "error", err, "batch", batchCount)
+			// Try to send error, but don't block indefinitely
 			select {
-			case LongJobStatusCh <- ErrRAGStatus:
+			case errorCh <- fmt.Errorf("worker %d batch %d: %w", workerID, task.batchIndex, err):
-			default:
+			case <-ctx.Done():
-				r.logger.Warn("LongJobStatusCh channel full, dropping message")
+				r.logger.Debug("embedding worker cancelled while sending error", "worker", workerID)
 			}
-			return fmt.Errorf("failed to embed batch %d: %w", batchCount, err)
+			return
 		}
-		if len(embeddings) != len(nonEmptyBatch) {
+
-			err := errors.New("embedding count mismatch")
+		// Send result with context awareness
-			r.logger.Error("embedding mismatch", "expected", len(nonEmptyBatch), "got", len(embeddings))
-			return err
-		}
-		// Write vectors to storage
-		filename := path.Base(fpath)
-		for j, text := range nonEmptyBatch {
-			vector := models.VectorRow{
-				Embeddings: embeddings[j],
-				RawText:    text,
-				Slug:       fmt.Sprintf("%s_%d_%d", filename, batchCount, j),
-				FileName:   filename,
-			}
-			if err := r.storage.WriteVector(&vector); err != nil {
-				r.logger.Error("failed to write vector to DB", "error", err, "slug", vector.Slug)
-				select {
-				case LongJobStatusCh <- ErrRAGStatus:
-				default:
-					r.logger.Warn("LongJobStatusCh channel full, dropping message")
-				}
-				return fmt.Errorf("failed to write vector: %w", err)
-			}
-		}
-		r.logger.Debug("wrote batch to db", "batch", batchCount, "size", len(nonEmptyBatch))
-		// Send progress status
-		statusMsg := fmt.Sprintf("processed batch %d/%d", batchCount, (len(paragraphs)+r.cfg.RAGBatchSize-1)/r.cfg.RAGBatchSize)
 		select {
-		case LongJobStatusCh <- statusMsg:
+		case resultCh <- batchResult{
-		default:
+			batchIndex: task.batchIndex,
-			r.logger.Warn("LongJobStatusCh channel full, dropping message")
+			embeddings: embeddings,
+			paragraphs: task.paragraphs,
+			filename:   task.filename,
+		}:
+		case <-ctx.Done():
+			r.logger.Debug("embedding worker cancelled while sending result", "worker", workerID)
+			return
+		}
+		r.logger.Debug("worker completed batch", "worker", workerID, "batch", task.batchIndex, "embeddings", len(embeddings))
+	}
+	r.logger.Debug("embedding worker finished", "worker", workerID)
+}
+
+// embedWithRetry attempts embedding with exponential backoff for API embedder
+func (r *RAG) embedWithRetry(ctx context.Context, paragraphs []string, maxRetries int) ([][]float32, error) {
+	var lastErr error
+
+	for attempt := 0; attempt < maxRetries; attempt++ {
+		if attempt > 0 {
+			// Exponential backoff
+			backoff := time.Duration(attempt*attempt) * time.Second
+			if backoff > 10*time.Second {
+				backoff = 10 * time.Second
+			}
+
+			select {
+			case <-time.After(backoff):
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			}
+
+			r.logger.Debug("retrying embedding", "attempt", attempt, "max_retries", maxRetries)
+		}
+
+		embeddings, err := r.embedder.EmbedSlice(paragraphs)
+		if err == nil {
+			// Validate embedding count
+			if len(embeddings) != len(paragraphs) {
+				return nil, fmt.Errorf("embedding count mismatch: expected %d, got %d", len(paragraphs), len(embeddings))
+			}
+			return embeddings, nil
+		}
+
+		lastErr = err
+		// Only retry for API embedder errors (network/timeout)
+		// For ONNX embedder, fail fast
+		if _, isAPI := r.embedder.(*APIEmbedder); !isAPI {
+			break
 		}
 	}
-	r.logger.Debug("finished writing vectors", "batches", batchCount)
+
-	r.resetIdleTimer()
+	return nil, fmt.Errorf("embedding failed after %d attempts: %w", maxRetries, lastErr)
-	select {
+}
-	case LongJobStatusCh <- FinishedRAGStatus:
+
-	default:
+// writeBatchToStorage writes a single batch of vectors to the database
-		r.logger.Warn("LongJobStatusCh channel is full or closed, dropping status message", "message", FinishedRAGStatus)
+func (r *RAG) writeBatchToStorage(ctx context.Context, result batchResult, filename string) error {
+	if len(result.embeddings) == 0 {
+		// Empty batch, skip
+		return nil
 	}
+
+	// Check context before starting
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	default:
+	}
+
+	// Build all vectors for batch write
+	vectors := make([]*models.VectorRow, 0, len(result.paragraphs))
+	for j, text := range result.paragraphs {
+		vectors = append(vectors, &models.VectorRow{
+			Embeddings: result.embeddings[j],
+			RawText:    text,
+			Slug:       fmt.Sprintf("%s_%d_%d", filename, result.batchIndex+1, j),
+			FileName:   filename,
+		})
+	}
+
+	// Write all vectors in a single transaction
+	if err := r.storage.WriteVectors(vectors); err != nil {
+		r.logger.Error("failed to write vectors batch to DB", "error", err, "batch", result.batchIndex+1, "size", len(vectors))
+		r.sendStatusNonBlocking(ErrRAGStatus)
+		return fmt.Errorf("failed to write vectors batch: %w", err)
+	}
+
+	r.logger.Debug("wrote batch to db", "batch", result.batchIndex+1, "size", len(result.paragraphs))
 	return nil
 }
 
@@ -250,22 +544,26 @@ func (r *RAG) LineToVector(line string) ([]float32, error) {
 	return r.embedder.Embed(line)
 }
 
-func (r *RAG) SearchEmb(emb *models.EmbeddingResp, limit int) ([]models.VectorRow, error) {
+func (r *RAG) searchEmb(emb *models.EmbeddingResp, limit int) ([]models.VectorRow, error) {
 	r.resetIdleTimer()
 	return r.storage.SearchClosest(emb.Embedding, limit)
 }
 
-func (r *RAG) SearchKeyword(query string, limit int) ([]models.VectorRow, error) {
+func (r *RAG) searchKeyword(query string, limit int) ([]models.VectorRow, error) {
 	r.resetIdleTimer()
 	sanitized := sanitizeFTSQuery(query)
 	return r.storage.SearchKeyword(sanitized, limit)
 }
 
 func (r *RAG) ListLoaded() ([]string, error) {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
 	return r.storage.ListFiles()
 }
 
 func (r *RAG) RemoveFile(filename string) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
 	r.resetIdleTimer()
 	return r.storage.RemoveEmbByFileName(filename)
 }
@@ -454,6 +752,9 @@ func (r *RAG) RerankResults(results []models.VectorRow, query string) []models.V
 }
 
 func (r *RAG) SynthesizeAnswer(results []models.VectorRow, query string) (string, error) {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	r.resetIdleTimer()
 	if len(results) == 0 {
 		return "No relevant information found in the vector database.", nil
 	}
@@ -482,7 +783,7 @@ func (r *RAG) SynthesizeAnswer(results []models.VectorRow, query string) (string
 		Embedding: emb,
 		Index:     0,
 	}
-	topResults, err := r.SearchEmb(embResp, 1)
+	topResults, err := r.searchEmb(embResp, 1)
 	if err != nil {
 		r.logger.Error("failed to search for synthesis context", "error", err)
 		return "", err
@@ -509,6 +810,9 @@ func truncateString(s string, maxLen int) string {
 }
 
 func (r *RAG) Search(query string, limit int) ([]models.VectorRow, error) {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	r.resetIdleTimer()
 	refined := r.RefineQuery(query)
 	variations := r.GenerateQueryVariations(refined)
 
@@ -525,7 +829,7 @@ func (r *RAG) Search(query string, limit int) ([]models.VectorRow, error) {
 			Embedding: emb,
 			Index:     0,
 		}
-		results, err := r.SearchEmb(embResp, limit*2) // Get more candidates
+		results, err := r.searchEmb(embResp, limit*2) // Get more candidates
 		if err != nil {
 			r.logger.Error("failed to search embeddings", "error", err, "query", q)
 			continue
@@ -543,7 +847,7 @@ func (r *RAG) Search(query string, limit int) ([]models.VectorRow, error) {
 	})
 
 	// Perform keyword search
-	kwResults, err := r.SearchKeyword(refined, limit*2)
+	kwResults, err := r.searchKeyword(refined, limit*2)
 	if err != nil {
 		r.logger.Warn("keyword search failed, using only embeddings", "error", err)
 		kwResults = nil
@@ -621,6 +925,8 @@ func GetInstance() *RAG {
 }
 
 func (r *RAG) resetIdleTimer() {
+	r.idleMu.Lock()
+	defer r.idleMu.Unlock()
 	if r.idleTimer != nil {
 		r.idleTimer.Stop()
 	}

rag/storage.go

@@ -102,6 +102,92 @@ func (vs *VectorStorage) WriteVector(row *models.VectorRow) error {
 	return nil
 }
 
+// WriteVectors stores multiple embedding vectors in a single transaction
+func (vs *VectorStorage) WriteVectors(rows []*models.VectorRow) error {
+	if len(rows) == 0 {
+		return nil
+	}
+	// SQLite has limit of 999 parameters per statement, each row uses 4 parameters
+	const maxBatchSize = 200 // 200 * 4 = 800 < 999
+	if len(rows) > maxBatchSize {
+		// Process in chunks
+		for i := 0; i < len(rows); i += maxBatchSize {
+			end := i + maxBatchSize
+			if end > len(rows) {
+				end = len(rows)
+			}
+			if err := vs.WriteVectors(rows[i:end]); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+	// All rows should have same embedding size (same model)
+	firstSize := len(rows[0].Embeddings)
+	for i, row := range rows {
+		if len(row.Embeddings) != firstSize {
+			return fmt.Errorf("embedding size mismatch: row %d has size %d, expected %d", i, len(row.Embeddings), firstSize)
+		}
+	}
+	tableName, err := vs.getTableName(rows[0].Embeddings)
+	if err != nil {
+		return err
+	}
+
+	// Start transaction
+	tx, err := vs.sqlxDB.Beginx()
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if err != nil {
+			tx.Rollback()
+		}
+	}()
+
+	// Build batch insert for embeddings table
+	embeddingPlaceholders := make([]string, 0, len(rows))
+	embeddingArgs := make([]any, 0, len(rows)*4)
+	for _, row := range rows {
+		embeddingPlaceholders = append(embeddingPlaceholders, "(?, ?, ?, ?)")
+		embeddingArgs = append(embeddingArgs, SerializeVector(row.Embeddings), row.Slug, row.RawText, row.FileName)
+	}
+	embeddingQuery := fmt.Sprintf(
+		"INSERT INTO %s (embeddings, slug, raw_text, filename) VALUES %s",
+		tableName,
+		strings.Join(embeddingPlaceholders, ", "),
+	)
+	if _, err := tx.Exec(embeddingQuery, embeddingArgs...); err != nil {
+		vs.logger.Error("failed to write vectors batch", "error", err, "batch_size", len(rows))
+		return err
+	}
+
+	// Build batch insert for FTS table
+	ftsPlaceholders := make([]string, 0, len(rows))
+	ftsArgs := make([]any, 0, len(rows)*4)
+	embeddingSize := len(rows[0].Embeddings)
+	for _, row := range rows {
+		ftsPlaceholders = append(ftsPlaceholders, "(?, ?, ?, ?)")
+		ftsArgs = append(ftsArgs, row.Slug, row.RawText, row.FileName, embeddingSize)
+	}
+	ftsQuery := fmt.Sprintf(
+		"INSERT INTO fts_embeddings (slug, raw_text, filename, embedding_size) VALUES %s",
+		strings.Join(ftsPlaceholders, ", "),
+	)
+	if _, err := tx.Exec(ftsQuery, ftsArgs...); err != nil {
+		vs.logger.Error("failed to write FTS batch", "error", err, "batch_size", len(rows))
+		return err
+	}
+
+	err = tx.Commit()
+	if err != nil {
+		vs.logger.Error("failed to commit transaction", "error", err)
+		return err
+	}
+	vs.logger.Debug("wrote vectors batch", "batch_size", len(rows))
+	return nil
+}
+
 // getTableName determines which table to use based on embedding size
 func (vs *VectorStorage) getTableName(emb []float32) (string, error) {
 	size := len(emb)

storage/storage.go

@@ -102,6 +102,22 @@ func NewProviderSQL(dbPath string, logger *slog.Logger) FullRepo {
 		logger.Error("failed to open db connection", "error", err)
 		return nil
 	}
+	// Enable WAL mode for better concurrency and performance
+	if _, err := db.Exec("PRAGMA journal_mode = WAL;"); err != nil {
+		logger.Warn("failed to enable WAL mode", "error", err)
+	}
+	if _, err := db.Exec("PRAGMA synchronous = NORMAL;"); err != nil {
+		logger.Warn("failed to set synchronous mode", "error", err)
+	}
+	// Increase cache size for better performance
+	if _, err := db.Exec("PRAGMA cache_size = -2000;"); err != nil {
+		logger.Warn("failed to set cache size", "error", err)
+	}
+	// Log actual journal mode for debugging
+	var journalMode string
+	if err := db.QueryRow("PRAGMA journal_mode;").Scan(&journalMode); err == nil {
+		logger.Debug("SQLite journal mode", "mode", journalMode)
+	}
 	p := ProviderSQL{db: db, logger: logger}
 	if err := p.Migrate(); err != nil {
 		logger.Error("migration failed, app cannot start", "error", err)