public class RagService
{
    private readonly IEmbeddingService _embedding;
    private readonly AppDbContext _db;

    public RagService(
        IEmbeddingService embedding,
        AppDbContext db)
    {
         _embedding = embedding;
         _db = db;
    }

    public async Task<RagResult> AskAsync(
        string question)
    {
        // 1. Embed the question
        var vector =
            await _embedding.CreateAsync(question);

        // 2. Retrieve relevant chunks
        var chunks =
            await _db.DocumentChunks
                .OrderBy(c => c.Embedding
                    .CosineDistance(vector))
                .Take(5)
                .ToListAsync();

        // 3. Build context for the LLM
        var context =
            BuildContext(chunks);

        // 4. Generate answer + citations
        return await GenerateAnswerAsync(
            question,
            context);
    }
}