Noob port writer can't get files into package artifact

Hi!,
I am making a port to learn and for myself.
This is a simple C project that creates
a static *.a file and a binary.

I am trying to get these into /usr/local/lib
and /usr/local/bin respectively.

The project's Makefile does not have an install
target so I am using the port's "do-install"
target to copy those files.

The fetch steps and build steps seem to work fine.
I can see the compiled code in /usr/ports/pobj/...

The files are copied successfully into the fake
port directory.

BUT TLDR, the packafe artifact is empty with
just the 2 files:
+CONTENTS +DESC
(which are empty)

As I'm writing this I am guessing "do-install"
is not the target I should be overriding, but
something earlier in the process?