Generate output that always parses.

using LMKit.Model;
using LMKit.TextGeneration;
using LMKit.TextGeneration.Sampling;

var model = LM.LoadFromModelID("qwen3.5:4b");

string jsonSchema = @"
{
  ""type"": ""object"",
  ""properties"": {
    ""name"":   { ""type"": ""string"" },
    ""amount"": { ""type"": ""number"" },
    ""tags"":   { ""type"": ""array"", ""items"": { ""type"": ""string"" } }
  },
  ""required"": [""name"", ""amount""]
}";

var grammar = Grammar.CreateJsonGrammar(jsonSchema);
var chat = new SingleTurnConversation(model) { Grammar = grammar };

var result = chat.Submit("Extract the order: Customer ACME ordered 12 units, tagged urgent and Q4.");
// result.Completion is GUARANTEED to parse as the schema above

using LMKit.Extraction;
using LMKit.TextGeneration.Sampling;

var elements = new List<TextExtractionElement>
{
    new("Vendor",        ElementType.String,    "Vendor company name"),
    new("InvoiceNumber", ElementType.String,    "Invoice identifier"),
    new("InvoiceDate",   ElementType.Date,      "Invoice issue date"),
    new("Total",         ElementType.Float,     "Total amount due"),
    new("LineItems",     ElementType.Object,    "Line items")
    {
        IsArray = true,
        InnerElements = new List<TextExtractionElement>
        {
            new("Description", ElementType.String),
            new("Quantity",    ElementType.Integer),
            new("UnitPrice",   ElementType.Float)
        }
    }
};

var grammar = Grammar.CreateJsonGrammarFromExtractionElements(elements);

using LMKit.TextGeneration.Sampling;

// Constrain output to one of a fixed set of values.
// Perfect for classification, routing, or multiple-choice answers.
var categories = new[] { "Billing", "Technical", "Sales", "Other" };
var grammar = Grammar.CreateGrammarFromValues(categories);

var chat = new SingleTurnConversation(model) { Grammar = grammar };

string ticket = "My credit card was charged twice for the same order.";
var result = chat.Submit($"Categorise this support ticket: {ticket}");
// result.Completion is exactly one of: Billing, Technical, Sales, Other