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.NET Integration

Use HttpClient with the documented gateway route for Chat Completions.

This method does not use a version-specific AI framework adapter.

Prerequisites​

  • Complete the Quickstart. Keep the gateway running.
  • Create a client API token for the application.
  • Use .NET 8 or a subsequent version.

Store the connection values in configuration or a secret manager:

export Verdictan__GatewayUrl="http://127.0.0.1:41002/v1/"
export Verdictan__ApiToken="vdt_..."
export Verdictan__Model="replace-with-configured-model"

The application token is different from the gateway runtime token. It is also different from the upstream provider credential.

Register the client​

using System.Net.Http.Headers;

builder.Services.AddHttpClient("Verdictan", client =>
{
    var gatewayUrl = builder.Configuration["Verdictan:GatewayUrl"]
        ?? throw new InvalidOperationException("Verdictan:GatewayUrl is required");
    var token = builder.Configuration["Verdictan:ApiToken"]
        ?? throw new InvalidOperationException("Verdictan:ApiToken is required");

    client.BaseAddress = new Uri(gatewayUrl);
    client.DefaultRequestHeaders.Authorization =
        new AuthenticationHeaderValue("Bearer", token);
    client.Timeout = TimeSpan.FromSeconds(60);
});

Keep the trailing slash on the configured /v1/ base URL. The slash gives relative request paths the /v1 prefix.

Send a chat request​

using System.Net;
using System.Net.Http.Json;
using System.Text.Json;

public sealed class GovernedChatService(IHttpClientFactory clients, IConfiguration config)
{
    public async Task<string> CompleteAsync(
        string input,
        CancellationToken cancellationToken = default)
    {
        var model = config["Verdictan:Model"]
            ?? throw new InvalidOperationException("Verdictan:Model is required");
        var payload = new
        {
            model,
            messages = new[] { new { role = "user", content = input } }
        };

        var response = await clients.CreateClient("Verdictan").PostAsJsonAsync(
            "chat/completions",
            payload,
            cancellationToken);

        var responseBody = await response.Content.ReadAsStringAsync(cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            string? code = null;
            try
            {
                using var errorBody = JsonDocument.Parse(responseBody);
                if (errorBody.RootElement.ValueKind == JsonValueKind.Object
                    && errorBody.RootElement.TryGetProperty("error", out var error)
                    && error.ValueKind == JsonValueKind.Object
                    && error.TryGetProperty("code", out var codeValue)
                    && codeValue.ValueKind == JsonValueKind.String)
                {
                    code = codeValue.GetString();
                }
            }
            catch (JsonException)
            {
                // The error response is not JSON. Do not expose its body.
            }

            if (response.StatusCode == HttpStatusCode.BadRequest
                && code == "content_policy_violation")
            {
                throw new InvalidOperationException("Request blocked by policy");
            }

            throw new HttpRequestException(
                $"Verdictan request failed with HTTP {(int)response.StatusCode}");
        }

        using var body = JsonDocument.Parse(responseBody);

        var content = body.RootElement
            .GetProperty("choices")[0]
            .GetProperty("message")
            .GetProperty("content");

        return content.ValueKind == JsonValueKind.String
            ? content.GetString() ?? string.Empty
            : throw new InvalidOperationException("Gateway returned invalid content");
    }
}

The model must match a configured gateway target. A name in the application configuration does not enable the model.

Verify health and authorization in different steps​

GET /healthz reports process health without a model request.

An authenticated GET /v1/models request verifies the application credential and the model catalog.

var client = clients.CreateClient("Verdictan");
var models = await client.GetAsync("models", cancellationToken);
models.EnsureSuccessStatusCode();

For an ASP.NET health indicator, select the applicable contract:

  • Probe /healthz for liveness without authentication.
  • Probe /v1/models with the named client for authenticated readiness.

Retry carefully​

Policy blocks (400 with error.code=content_policy_violation) are not temporary. Authentication failures (401 or 403) are also not temporary.

A 429 or 5xx response can be temporary. A timeout can occur after the provider accepts the request.

If the application has no policy for duplicate work and cost, do not add automatic model retries.

Verify the governed path​

verdictan policy lint --file policy-config.yaml
verdictan events tail --since 10m --follow

While the event tail is active, send a representative .NET request. A matching request ID shows that the gateway delivered Event evidence to the control plane.

Next steps​