Ah, after a week a light finally shines.
The closest thing I could see as an “error” was in the CLI.
Ember inspector never showed the route, and console never showed any errors or log messages.
So as far as I could tell the code was never getting to Ember.
Anyway …
I have 2 localhost Discourse installs. Both are
Windows 10 → VMware → Ubuntu 16.04 LTS
One I followed an earlier version (sans the DO stuff) of
discourse/docs/INSTALL-cloud.md at main · discourse/discourse · GitHub
the other
Install Discourse on Ubuntu or Debian for Development
The first I have been using more as a non-techy Admin to test Discourse operations and occasionally a “beta” plugin.
The second for “hacks” i,e. modified Core code, and “pre-alpha” plugins.
A reason is I want to keep the first as “clean” of my muddy footprints as I can, but also workflow.
For example, the first is
tweak - push - rebuild app - test - repeat
the second is the easier and faster
tweak - exec rails s - test - repeat
Though you code does not work on my “hack” install, it does work on my “clean” install.
Other than the second involving Vagrant, a difference is the firsts root is “localhost” and the seconds is “localhost:3000” - with a port number
I did enter “3000” in Admin → Developers and Discourse uses it for internal URLs but I’m guessing the presence of the port has very much to do with the road block I was hitting.