[Blazor] Hot reload on webassembly not working when loading the webassembly runtime as the result of an enhanced navigation request

[javiercn]

• New -> Per page interactivity -> wasm
• Print Console.WriteLine(Environment.GetEnvironmentVariable("DOTNET_MODIFIABLE_ASSEMBLIES")) in the first line on Program.cs
• Launch with hot reload enabled
• Navigate to Counter
• Check the dev console. Debug should be printed but it isn't.

[maraf]

It doesn't work for enhanced navigation because of this check https://github.com/dotnet/sdk/blob/main/src/BuiltInTools/HotReloadAgent.WebAssembly.Browser/wwwroot/Microsoft.DotNet.HotReload.WebAssembly.Browser.lib.module.js#L5C36-L5C123

Enhance navigation is removing the aspnetcore-browser-refresh.js script from the page, because it's not part of the response HTML. See https://github.com/dotnet/sdk/blob/main/src/BuiltInTools/BrowserRefresh/BrowserRefreshMiddleware.cs#L176, sec-fetch-dest header must be document, but it's empty for enh-nav

Tail of the enh-nav request to counter

Tail of the F5 request to counter

I'm not sure why it manifests now, because before the hotreload init refactoring, we had the exact same check in the runtime repo. The same behavior can be reproduced with Preview 6.

We should include the script even for enh-nav requests, we can duplicate this https://github.com/dotnet/aspnetcore/blob/main/src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Streaming.cs#L327-L332 in the HotReload tooling when checking for sec-fetch-dest header

[javiercn]

Closed by dotnet/sdk#50578 and dotnet/sdk#50580

/cc: @maraf