Runic.Assets 0.10.0

Runic.Assets

Runic.Assets gives a .NET application one portable, validated description of its static files. Embed a Vite build for NativeAOT-friendly deployment, use explicit assembly resources for a small bundle, or use a refreshable directory while developing—then attach the same IAssetSource to the host adapter you choose.

Runic.Assets or the Views www/ folder

Runic has two ways to ship a frontend, and they do not share settings:

• Runic.Application.Views applications build RunicApplicationFrontendDirectory and copy its dist/ as loose files to www/ next to the executable; the Views host serves that folder. This is the default for Runic Views apps, and dotnet runic dev works with it. Without a Vite or Angular development server, dev has the Runic Desktop host serve dist/ itself through DevelopmentDirectoryAssetSource, before www/, and reload its windows when dist/ changes.
• Runic.Assets packs RunicAssetsDist into one validated archive and embeds it in the assembly. Use it for ASP.NET Core and for Runic Desktop applications without Views, or wherever a single-file or NativeAOT deployment must carry its frontend inside the executable. Runic.Assets.AspNetCore and Runic.Assets.Desktop serve it.

A Views application can serve an embedded archive instead of www/ by setting RunicDesktopHost.SurfaceOptions to a DesktopSurfaceOptions whose Content is new DesktopContent.Handler(assets.ToDesktopContentHandler()). The archive must then hold everything the build copies to www/, including the host's runic-views.js client, and dotnet runic dev then serves it instead of the live dist/. A build property that connects the two pipelines is planned for a later 1.x release.

Install

dotnet add package Runic.Assets --prerelease

The package targets .NET 10, has no UI or web-framework dependency, and is currently in preview. Install Runic.Assets.AspNetCore or Runic.Assets.Desktop only when you also need that delivery integration.

Embed a Vite build

After your Vite project's npm run build creates dist, add this to the .NET application project:

<PropertyGroup>
  <RunicAssetsDist>../Client.Web/dist</RunicAssetsDist>
</PropertyGroup>

dotnet build incrementally creates a canonical archive and embeds it through the packer's trusted generated-output snapshot mode. It works on Linux, Windows, and macOS, rejects observed symbolic links and reparse points, and assumes its frontend output is not concurrently hostilely mutated. Load the default Runic.Assets.StaticFiles resource at runtime:

using System.Reflection;
using Runic.Assets;

AssetArchiveSource assets = AssetArchive.ReadEmbedded(
    Assembly.GetExecutingAssembly());

The default entry point is index.html. Set RunicAssetsEntryPoint for a different entry file; set RunicAssetsDistExclude to omit files such as build statistics (by default runic-assets.zip; the value replaces that default, and an empty <RunicAssetsDistExclude></RunicAssetsDistExclude> in the project file packs every file). To use an existing canonical archive, set RunicAssetsEmbeddedArchive instead of RunicAssetsDist. Set RunicAssetsEmbeddedResourceName if you need a resource name other than Runic.Assets.StaticFiles, and supply that name to ReadEmbedded. To produce an archive in a separate step, run the packaged packer directly; see the packer README.

Directory archives mark a file Immutable (public, max-age=31536000, immutable) only when its name carries a content hash, such as Vite's index-Cf3tzbYH.js, SvelteKit's start.D2kX0q3e.js or webpack's main.<hex>.js. Every other file, including .html/.htm documents and unhashed public/ files such as favicon.ico, robots.txt or sw.js, uses Revalidate with its strong entity tag.

Small explicit bundles

For a few hand-authored files, declare assembly resources in your application project and map them explicitly:

<ItemGroup>
  <EmbeddedResource Include="Assets/index.html" />
  <EmbeddedResource Include="Assets/app.css" />
</ItemGroup>

using Runic.Assets;

var assets = new EmbeddedAssetSource(
    typeof(Program).Assembly,
    [
        new("index.html", "MyApp.Assets.index.html", IsEntryPoint: true),
        new("assets/app.css", "MyApp.Assets.app.css",
            CacheMode: AssetCacheMode.Immutable),
    ]);

Use DevelopmentDirectoryAssetSource for a development inner loop on Linux, Windows or macOS. dotnet runic dev uses it when no Vite or Angular development server runs: the Runic Desktop window serves the frontend output directory and reloads when it changes (dotnet-runic). The source refreshes local files and marks them no-store. No path component below the root may be a symbolic link or reparse point. On Linux and macOS the source pins its root with one no-follow directory handle and opens every file relative to it, so replacing the root or an ancestor cannot redirect a published source. Windows checks each path component for a reparse point before it opens a file, but does not pin the root: a directory moved into the root's place is read from then on. That is enough for a development source that serves your own build output. Entries whose names are not valid asset paths (for example containing :, ?, # or a backslash) are skipped and listed in SkippedEntries instead of failing the scan.

using var source = new DevelopmentDirectoryAssetSource(frontendDirectory, "index.html");
source.Changed += (_, change) => Reload(change.Current);
source.StartWatching(new AssetWatchOptions { DebounceDelay = TimeSpan.FromMilliseconds(100) });
// Dispose the source to stop watching.

Subscribe to Changed (IAssetSourceChangeNotifier) first, then call StartWatching once: it coalesces filesystem signals into source-owned refreshes and runs until the source is disposed, which is the only way to stop it; a second call throws InvalidOperationException. RefreshAsync scans the directory on demand and returns the current manifest; refreshes run one at a time. The source is the single publisher and each event contains immutable previous/current manifest snapshots. Notifications are serialized and coalesced after refresh, subscriber failures are isolated, and disposal stops future refreshes. The watcher uses one fixed 8 KiB native event buffer and retries from the authoritative directory scan after overflow, or after a scan that fails because a build left the directory half written, with at most three retries per change burst by default (AssetWatchOptions.MaxRetryAttempts). Reads materialize a verified temporary-file snapshot, so content that changes after publication is rejected rather than delivered under the old digest. Use an embedded source or an archive for a reproducible deployed bundle.

Sources

Every source implements IAssetSource: its immutable Manifest, ValidateAsync, and OpenAsync(relativePath), which returns an AssetReadSnapshot. The snapshot's Descriptor and Content stream are one owned unit, so response entity tags and range metadata describe exactly the bytes delivered; dispose the snapshot to close the stream. A custom source implements these three members. OpenAsync throws FileNotFoundException for a path the manifest does not declare.

Guarantees and limits

AssetPath rejects rooted, traversal, encoded, ambiguous, and control-character paths. AssetPath.TryNormalize, AssetManifest.TryGetAsset and AssetManifest.TryResolveRequestPath return false for such paths instead of throwing, so request handlers can pass untrusted paths to them directly. AssetManifest is immutable and ordinally ordered. Each entry carries media type, length, SHA-256 digest, strong entity tag, Subresource Integrity token, and cache policy. CSP is host policy rather than archive content: the archive cannot safely invent an application's script or connect origins. ASP.NET Core delivery supports RFC conditional requests and single byte ranges directly from this metadata. Archive reads validate declared content and can be bounded with AssetArchiveReadOptions when input is not trusted.

AssetArchive.Inspect returns an archive's schema version, its manifest and the SHA-256 digest of the canonical manifest bytes. Readers accept only the current runic.assets.archive/1 schema and reject incompatible archive versions.

For application integration, consume IAssetSource.Manifest directly for asset identity, SHA-256, entity tags, and cache metadata. Do not recreate a parallel manifest in a hosting adapter.

This package deliberately does not expose HTTP endpoints or a Desktop handler; choose a host adapter for that responsibility.

Documentation and support

• Runic Assets documentation
• Vite archive consumer example
• Issues and support
• MIT License