> Then maybe we can rename `/mindplay` (at top level) to `src`?

You can get rid of a whole level of folders - just start with `src` as the root of the `mindplay\annotations` namespace, since everything is going to exist in that namespace.

Something along the lines of:

    "autoload": {
        "psr-4": {"mindplay\\annotations\\": "src/"}
    }

You can boostrap the unit-test manually:

    $loader = require 'vendor/autoload.php';
    $loader->add('mindplay\\annotations\\test\\', __DIR__ . '/test/');

This way the test namespace won't autoload anywhere except the test-suite.