There are a few things that can be done. +We are considering adding options to the IDE that should avoid some of the donkey work to implement it.

The following guide for "dot_a_linkage" and "precompiled" gives some insight. https://wiki.seeedstudio.com/Software-Static-Library/. ;

Ignore the article when it explains how to see verbose output and the build folder. You can follow the guide in the yellow box above to enable verbose output. 

Visual Micro uses the same build rules as the arduino ide which is why the above link also applies.

After changing library or build commands outside of the ide, either click "vMicro>General>Reload toolchains" or restart the ide.

Does this help?

You can put .a files in a \libs folder below the project/sketch folder. They will automatically be linked. The dot_a_linkage flag would allow you to build a ".a"

However it's all a bit clunky and we suspect the end result will leave you without any intellisense for the linked libs.

We are working on a "one-click" solution that will allow the library sources to remain as they are (for various reasons, such as intellisense and update/changed lib sources validation). The result should be faster library deep search, faster compilation with shorter build commands whilst still being Arduino compatible.

Click the notifications button in the new releases section of this forum for interim release notifications.

Hope that helps

Yes you were clear and we are talking about the same thing. Behind the scenes it would simply implement the arduino spec for precompile but that complexity would be hidden from users (except when verbose is enabled).

An initial release of this functionality is now available, and documented below:
https://www.visualmicro.com/page/How-to-Automatically-Pre-Compile-Library-Archiv...

This does not (yet) automatically rebuild the archive when the code changes, or when a different board architecture is selected.