HTTP responses to App Engine admin users aren't cacheable

[derat]

App Engine annoyingly mangles headers on HTTP responses to admin users to disable caching. It does this intentionally since those responses have X-AppEngine-Resource-Usage and X-AppEngine-Estimated-CPM-US-Dollars headers, but it means that browsers don't cache cover images or MP3s (I think -- Chrome seems to cache media files so aggressively that I wouldn't be surprised if it ignored what the server tells it).

I filed https://issuetracker.google.com/issues/179471500 but I assume I won't even get a reply.

I haven't figured out any workarounds yet. Maybe I could use Cloud Load Balancing to re-add the headers, but that seems like overkill.

[derat]

Also posted https://stackoverflow.com/q/66342766/6882947 to see if anyone has found a workaround.

[derat]

I looked into the possibility of using a Chrome extension to modify the response headers, but chrome.webRequest.onHeadersReceived doesn't allow the modification of cache-related headers: https://bugs.chromium.org/p/chromium/issues/detail?id=355232

It seems like using a non-admin account is the best option for now.