feat: add fts indexing

db/fts.go

@@ -0,0 +1,76 @@
+package db
+
+import (
+	"context"
+	"strings"
+)
+
+// UpsertFileContent replaces the FTS content for a given file_id.
+func (q *Queries) UpsertFileContent(ctx context.Context, fileID int64, content string) error {
+	// Delete existing content for this file
+	if _, err := q.db.ExecContext(ctx, `DELETE FROM file_contents WHERE file_id = ?`, fileID); err != nil {
+		return err
+	}
+	// Insert new content
+	_, err := q.db.ExecContext(ctx, `INSERT INTO file_contents (file_id, content) VALUES (?, ?)`, fileID, content)
+	return err
+}
+
+// DeleteFileContentByFileID removes FTS content for a file.
+func (q *Queries) DeleteFileContentByFileID(ctx context.Context, fileID int64) error {
+	_, err := q.db.ExecContext(ctx, `DELETE FROM file_contents WHERE file_id = ?`, fileID)
+	return err
+}
+
+// DeleteStaleFileContents removes FTS content for files not in the given path list.
+func (q *Queries) DeleteStaleFileContents(ctx context.Context, paths []string) error {
+	if len(paths) == 0 {
+		_, err := q.db.ExecContext(ctx, `DELETE FROM file_contents`)
+		return err
+	}
+	placeholders := make([]string, len(paths))
+	args := make([]interface{}, len(paths))
+	for i, p := range paths {
+		placeholders[i] = "?"
+		args[i] = p
+	}
+	query := `DELETE FROM file_contents WHERE file_id NOT IN (
+		SELECT id FROM files WHERE path IN (` + strings.Join(placeholders, ",") + `)
+	)`
+	_, err := q.db.ExecContext(ctx, query, args...)
+	return err
+}
+
+// SearchResult holds a single FTS search hit.
+type SearchResult struct {
+	FileID int64
+	Path   string
+	Snippet string
+}
+
+// SearchFileContents performs a full-text search across all file contents.
+// Returns matching file paths with a snippet of the match context.
+func (q *Queries) SearchFileContents(ctx context.Context, query string, limit int) ([]SearchResult, error) {
+	rows, err := q.db.QueryContext(ctx, `
+		SELECT fc.file_id, f.path, snippet(file_contents, 1, '>>>', '<<<', '...', 20)
+		FROM file_contents fc
+		JOIN files f ON f.id = fc.file_id
+		WHERE file_contents MATCH ?
+		ORDER BY rank
+		LIMIT ?
+	`, query, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var results []SearchResult
+	for rows.Next() {
+		var r SearchResult
+		if err := rows.Scan(&r.FileID, &r.Path, &r.Snippet); err != nil {
+			return nil, err
+		}
+		results = append(results, r)
+	}
+	return results, rows.Err()
+}