Hot reload

dotnet watch reloads the browser when a file changes. For C# that works out of the box. For .ts it needs one line, because in its default hot reload mode dotnet watch runs no build when a .ts file is saved, so the .js would go stale.

Turn it on

<PackageReference Include="Extrode.Pare.AspNetCore" Version="0.6.2" />

using Extrode.Pare.AspNetCore;

builder.AddPareDevelopment();   // before builder.Build(); does nothing outside Development

Now this happens on every save:

• At start-up the app strips every source that is out of date.
• It reads Extrode.Pare.development.json, which the build puts next to the app and never publishes, to know where each source's output goes.
• A rejected file is logged as file:line:col: error PARE... and the old .js stays.
• Deleting a source deletes its output under obj/.
• It covers sources served with PareServeAt and sources of a Razor class library that the app references as a project.

If you set PareOutDir, pass the same folder: builder.AddPareDevelopment(o => o.OutDir = "...").

AddPareDevelopment also adds dotnet watch's browser refresh to WebApplication.CreateSlimBuilder apps, which never run the hosting startup that adds it.

Limits

• A .ts file added while dotnet watch runs is stripped, but the page gets 404 for it until the next build. Press Ctrl+R in dotnet watch to rebuild. The log says so.
• A request for a deleted source's output answers 500 in Development until the next build.
• In Development the server still serves .ts source files on disk with a warning. MapStaticAssets serves any file on disk in Development, and UseStaticFiles serves everything under wwwroot. Published output never contains them.

If it does not reload

• PublishAot project: add <StartupHookSupport Condition="'$(Configuration)' == 'Debug'">true</StartupHookSupport>. Without it dotnet watch says "Project does not support Hot Reload".
• Run dotnet watch from the project directory. With --project from another folder, .NET SDK 10.0.401 on macOS fails to read obj\Debug/.../staticwebassets.development.json and never refreshes the page.
• No package? dotnet watch --no-hot-reload rebuilds and restarts on every save (about 3 seconds on the sample) and you reload the page yourself.