AArnott

Nerdbank.JsonRpc on NetWasm (netwasm0.1): proof-of-concept report

Prepared by an AI agent (Grok Bot) on Andrew Arnott's behalf. Started 2026-09-29 22:32 MDT. See "Time spent" at the end.

TL;DR: what works

• Nerdbank.JsonRpc multitargets netwasm0.1. It sits alongside net9.0, net8.0, net472 and netstandard2.0, and packs to a single nupkg (Nerdbank.JsonRpc.0.2.6-netwasm, which has lib/NetWasm,Version=v0.1/).
• End-to-end browser demo works, verified in headless Chrome.

AArnott

$vs = & "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe" -prerelease -format json -latest | ConvertFrom-Json
$instanceId = $vs[0].instanceId
$installationPath = $vs[0].installationPath
Import-Module "$installationPath\Common7\Tools\Microsoft.VisualStudio.DevShell.dll"
Enter-VsDevShell $instanceId -SkipAutomaticLocation -Arch x64 -HostArch x64

AArnott

# git bisect start --first-parent 5283fb074640b1 23d9058db6921f0f4849cd78d726e6cbb375c46c -- src/Nerdbank.MessagePack
# git bisect run pwsh.exe ./GetSize.ps1
$env:UseSharedCompilation='false' # prevent dotnet.exe from locking up between iterations
Write-Host "Git clean" -ForegroundColor Yellow
git clean -fdX -e obj/tools :/
Write-Host "Running init" -ForegroundColor Yellow
./init.ps1 -InstallLocality repo
if ($LASTEXITCODE -ne 0) { Write-Host "Aborting after exit code $LASTEXITCODE"; exit 125 }
Write-Host "Running publish" -ForegroundColor Yellow
dotnet publish test\AotNativeConsole

AArnott

using System.Diagnostics;
using System.Runtime.CompilerServices;

internal static class AvoidCrashingOnDebugAsserts
{
    [ModuleInitializer]
    internal static void Initializer()
    {
        if (Trace.Listeners.OfType<DefaultTraceListener>().FirstOrDefault() is { AssertUiEnabled: true } defaultListener)
        {

AArnott

{
  "type": "object",
  "title": "Model Context Protocol Servers",
  "additionalProperties": false,
  "properties": {
    "$schema": {
      "type": "string",
      "format": "uri"
    },
    "inputs": {

AArnott

using Nerdbank.MessagePack; // Comes from the Nerdbank.MessagePack nuget package
using PolyType;

namespace MessagePackBug;

[GenerateShape]
public partial record ItemsRequest(
	[property:Key(0)]
	string Prop1,

AArnott

using System.Reflection.Metadata;

class CustomAttributeTypeProvider : ICustomAttributeTypeProvider<Type>
{
    internal static readonly CustomAttributeTypeProvider Instance = new();

    public Type GetPrimitiveType(PrimitiveTypeCode typeCode)
    {
        return SignatureTypeProvider.Instance.GetPrimitiveType(typeCode);
    }

AArnott

Function Encrypt-DataAsymmetric {
    [CmdletBinding()]
    Param
    (
        [Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true, Position = 0)]
        [byte[]]$Data,
        [Parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true, Position = 1)]
        [byte[]]$PublicKey
    )

AArnott

# Inspired by https://github.com/MicrosoftDocs/azure-devops-docs/blob/main/docs/pipelines/agents/docker.md#linux
FROM ubuntu:22.04
ENV TARGETARCH="linux-x64"
# Also can be "linux-arm", "linux-arm64".

# Add a Capability that pipelines can filter to when they require a linux agent that supports creating docker containers.
ENV HasDockerAccess="true"

RUN apt-get update
RUN apt-get upgrade -y

AArnott

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;

class Program
{
    static void Main(string[] args)
    {
        var ordinary = RunTest(OrdinaryDictionaryRun);