Use cases, before and after.

// The wording, the examples and the scale are compiled in: changing them means a build and a deployment.
private const string Instructions =
    "Rate the urgency of this order email from 1 (routine) to 5 (critical). Answer with the number only. " +
    "Examples: \"Line 3 is down until the bearings arrive. Ship today.\" is 5; " +
    "\"Please restock these when convenient, no rush.\" is 1.";
private const int Minimum = 1, Maximum = 5, MaxAttempts = 2;

public static async Task<int?> ClassifyUrgencyAsync(IChatClient chat, string email, CancellationToken ct = default)
{
    List<ChatMessage> messages = [new(ChatRole.System, Instructions), new(ChatRole.User, email)];
    for (var attempt = 1; attempt <= MaxAttempts; attempt++)
    {
        var response = await chat.GetResponseAsync<int>(messages, cancellationToken: ct);
        string problem;
        if (!response.TryGetResult(out var urgency)) problem = "The answer was not a whole number.";
        else if (urgency is < Minimum or > Maximum) problem = $"{urgency} is outside {Minimum} to {Maximum}.";
        else return urgency;

        // Retry with the finding.
        messages.AddMessages(response);
        messages.Add(new(ChatRole.User, $"{problem} Answer again with a whole number from {Minimum} to {Maximum}."));
    }
    return null;   // no valid answer after MaxAttempts
}

public sealed record TicketGroup
{
    public required string Label { get; init; }
    public required int[] Indices { get; init; }
}

public static class TicketGroupingBefore
{
    private const string Instructions =
        "Group these tickets by whether each reports a defect or asks for a feature. Each ticket starts with its " +
        "zero-based index. Return groups with a short label and the indices in them; every index in exactly one group.";

    public static async Task<Dictionary<string, List<Ticket>>?> GroupAsync(IChatClient chat, IReadOnlyList<Ticket> tickets, CancellationToken ct = default)
    {
        // The model sees indices, so the answer can be mapped back to the original objects.
        var numbered = string.Join("\n", tickets.Select((t, i) => $"{i}: {t.Title} ({t.Severity})"));
        List<ChatMessage> messages = [new(ChatRole.System, Instructions), new(ChatRole.User, numbered)];
        for (var attempt = 1; attempt <= 2; attempt++)
        {
            var response = await chat.GetResponseAsync<List<TicketGroup>>(messages, cancellationToken: ct);
            var problems = new List<string>();
            if (!response.TryGetResult(out var groups) || groups is null)
                problems.Add("The answer was not a list of groups with a label and indices.");
            else
            {
                var indices = groups.SelectMany(g => g.Indices).ToList();
                problems.AddRange(indices.Where(i => i < 0 || i >= tickets.Count).Distinct()
                    .Select(i => $"Index {i} is out of range 0..{tickets.Count - 1}."));
                if (indices.Count != tickets.Count || indices.Distinct().Count() != tickets.Count)
                    problems.Add($"Every index from 0 to {tickets.Count - 1} must appear in exactly one group.");
                if (groups.Select(g => g.Label).Distinct(StringComparer.OrdinalIgnoreCase).Count() != groups.Count)
                    problems.Add("Group labels must be unique.");
                if (problems.Count == 0)
                    return groups.ToDictionary(g => g.Label, g => g.Indices.Select(i => tickets[i]).ToList(), StringComparer.OrdinalIgnoreCase);
            }

            // Retry with the findings.
            messages.AddMessages(response);
            messages.Add(new(ChatRole.User, "Problems with your answer:\n" + string.Join("\n", problems)));
        }
        return null;
    }
}