Just wanted to say thank you to whoever changed Email Workers to be able to reply to threaded emails
Just wanted to say thank you to whoever changed Email Workers to be able to reply to threaded emails, itβs such a huge improvement 
sourceResponse.body no such issues occur, so i assume tis something with the pipe?
watch to watch the dir for changes and trigger a rebuild automagically-- flag is that it is an npm specifc flag indicating the end of options for npm specific commands, such that in the case you mentioned that yarn dev becomes a command line option for the wrangler pages dev command. In that case, my next step would probably be to figure out if there is a flag on this page that does what you are looking for: https://developers.cloudflare.com/workers/wrangler/commands/#devwatch since that is typically how these things work anyways, but that is where I would look if I better understood the specifics of your needs.
yarn dev would output anywayworkerd, with all of the bells and whistles that a Worker would havesourceResponse.bodywatchwatch--yarn devyarn devwrangler pages devworkerd const { readable, writable } = new TransformStream();
// Start pumping the body. NOTE: No await!
sourceResponse.body.pipeTo(writable, {preventClose: true});
return new Response(readable, {....})