Adds a Blazor WebAssembly (.NET 10) + Motoko Hello World template.

[mitnick2012]

Overview
The icp-cli templates library has no support for .NET/C# developers who want to
build on ICP using Blazor WebAssembly. This template fills that gap by providing
a working starter project that combines Blazor WASM (.NET 10) on the frontend with
a Motoko canister on the backend, using icp-cli for deployment. Without this template,
.NET developers face undocumented pitfalls that make getting started unnecessarily
difficult.

Requirements

• Blazor WASM frontend that successfully calls a Motoko backend canister
• Uses icp-cli with canister.yaml configuration (not dfx)
• Works on local network and mainnet
• Documents all known gotchas specific to Blazor + ICP
• No JS interop race conditions between @dfinity/agent and Blazor runtime
• Canister ID discovery via ic_env cookie without hardcoding

Considered Solutions

1. ES module script (type="module") for @dfinity/agent — rejected due to browser
   deferral behavior causing a race condition where Blazor attempts JS interop before
   the module is ready, silently breaking button events.
2. Webpack bundle loaded with defer — selected. Compiles @dfinity/agent into a
   single plain JS file exposed as window.IcpAgent. The defer attribute guarantees
   script execution order before DOMContentLoaded, so the global is always available
   when Blazor makes its first JS interop call.

Recommended Solution
Webpack + defer loading pattern, modeled after the existing Dfinity.Blazor
community library. This is the only approach that reliably solves the JS interop
race condition without adding complexity to the Blazor startup sequence. It also
bundles @dfinity/agent locally (no CDN dependency), pins the version in package.json,
and produces a single minified file that the asset canister can certify correctly.

Considerations

• Security: No impact. The template follows the same trust model as other icp-cli
  templates — no private keys, no hardcoded canister IDs.
• Performance: The webpack bundle adds ~271KB (uncompressed) to the frontend assets.
  This is negligible compared to the Blazor WASM runtime (~5MB+). Brotli compression
  via the asset canister reduces the bundle to ~80KB on the wire.
• Users: Purely additive. Existing templates are unaffected. .NET developers gain
  a working starting point without having to discover undocumented pitfalls.
• Breaking changes: None.
• Maintenance: Low. The template depends on @dfinity/agent and the @dfinity/motoko
  recipe — both of which are maintained by DFINITY. The .NET 10 LTS support window
  runs until November 2028, so no forced upgrade in

[mitnick2012]

Hello @marc0olo,
Could you please review this feature?

[marc0olo]

Hey @mitnick2012,

I will discuss with the team how to handle this. But I don't think we want to maintain external examples here in this repo.

In any case this would be better suited for the https://github.com/dfinity/icp-cli-templates repository. See this guide on how to create and use custom templates: https://cli.internetcomputer.org/1.0/guides/creating-templates

What I could imagine is that we provide an overview for community created templates either in the official icp-cli documentation or in the README of the icp-cli-templates repository.

I also noticed that you depend on @dfinity/agent in your example. You should migrate this to https://js.icp.build/core/latest/libs/agent

Also note that the latest Motoko recipe (v5.0.0) delegates the compilation entirely to mops build:

• https://github.com/dfinity/icp-cli-recipes/releases/tag/motoko-v5.0.0
• https://github.com/dfinity/icp-cli-templates/blob/main/hello-world/motoko-backend/mops.toml

Best,
Marco

[mitnick2012]

Thanks @marc0olo for the review I will update the MR with your remarks, and move it to template repo, my aim is to give the blazor users a starting push to build with icp

[marc0olo]

@mitnick2012 for now my recommendation is following:

• create a "real" template as per guide above
• create a forum post about this template, share its github repo and advertise the command how to use it

independent of that I will think about how we can provide a registry for independent templates created by the community.