I've followed up to here but haven't been able to "respond to the request using the REPL". And the video goes very fast at that moment, I might have missed a beat.

ok. It means in the console tab you can type response.send("foo") then unpause debugger (when you have a live request caught). there are a few gotchas like the request timing out while in debugger, I might expand this a bit

Got it! thank you

I'm seeing errors here: > endpoint = RuntimeError: File not found: firebase-app.js

urgh, I un-vendored the firebase dependencies and deleted the file attachments so I get the error maps working but now all pinned dependencies break, the very opposite aim for pinned dependencies, lol