Serve an application's MediaEntity<T> originals and named recipes through controller-owned HTTP routes. The reference supplies discovery, conditional/cache headers, bounded request parsing, format negotiation, and optional persisted derivatives.

dotnet add package Sylin.Koan.Media.Web

Smallest meaningful result

using Koan.Core;
using Koan.Media;
using Koan.Media.Abstractions.Recipes;
using Koan.Web.Extensions;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddKoan().AsWebApi();

var app = builder.Build();
await app.RunAsync();

public sealed class Photo : MediaEntity<Photo> { }

public static class PhotoRecipes
{
    [MediaRecipe("card", Description = "320px JPEG card")]
    public static MediaRecipe Card() => MediaRecipe.New()
        .Resize(width: 320)
        .EncodeAs("jpeg", Quality.Web)
        .Build();
}

One concrete MediaEntity<T> is selected automatically. The application still needs Data and Storage providers for its Photo Entity; no registration helper or application rendering controller is required.

When the application has several media Entity types, select the one that owns the bare route deliberately:

builder.Services.AddMediaSource<Photo>();
builder.Services.AddKoan().AsWebApi();

A custom IMediaSource is the equivalent override for a non-Entity source. Zero or several candidates without an override reject host startup with that correction.

Routes

GET /media/{id} — original bytes;
GET /media/{id}/{recipe} — named recipe or supported format shortcut;
GET /media/{id}/{recipe}?w=...&q=... — allowlisted overrides;
GET /media/recipes — materialized catalog and shortcuts; and
GET /media/recipes/{name}?as=appsettings — canonical recipe configuration.

MediaEntitySource<TEntity> resolves the source through the Entity data path before consulting a derivative, so active tenancy and access axes gate both cold and warm requests.

Current limits

one bare /media/{id} route has one IMediaSource; applications with multiple media Entity types must choose one source or own a discriminating custom source;
the default source buffers a completed render before persisting its derivative;
derivative writes are best-effort and source deletion does not automatically reclaim derivative storage;
there is no upload-time prewarm, signed route, or content-addressed route shape; and
routes are currently fixed under /media.

See the Media reference and technical companion.