The home page reaches the real $app/navigation through AlbumCard and
AlbumMenu. That loads SvelteKit's client runtime, whose $app/paths reads
__SVELTEKIT_PAYLOAD__ at module load. The global is only there when the
kit plugin's define reaches the module, and under vitest that is not
reliable: page.test.ts failed to load on CI run 6576 and passed on its
re-run. #374 was the same class of failure.
vitest.setup.ts now mocks $app/navigation, $app/state and $app/paths for
every test. Per-file mocks still win. A small guard test fails if the
suite-wide mocks are removed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
