Revisit hot reload browser refresh script injection

[MackinnonBuck]

Our hot reload mechanism relies on the aspnetcore-browser-refresh.js script being injected into the webpage so the browser can automatically refresh with hot reload changes.

We currently do this with a special middleware that searches for the last closing </body> tag in HTML responses and injects a <script src="/_framework/aspnetcore-browser-refresh.js"></script> element just before it. However, this mechanism is very fragile because it fails when the response can't be easily parsed (e.g., response compression is enabled, the closing </body> tag is split between response stream writes, etc.).

We should consider an approach where we somehow reference the browser refresh script directly rather than using this script injection middleware.

Additional considerations

Make sure we also address the following issues:

• Refused to load _framework/aspnetcore-browser-refresh.js due to CSP #33068
• HotReload is not working in ASP.NET Core in VS2022 or dotnet watch run when ServiceWorkers are installed/running #39715

Thanks for contacting us.

We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.