The test relied on the post-login landing page implicitly, so the
custom_styles <link> coverage could silently evaporate if that landing
changes. Visit root_url explicitly (matching the writebook sibling) to pin
the page under test. Assertions are unchanged and still non-vacuous.
Add a headless-browser system test that stores a </style><script> payload
in custom_styles, loads a page, and asserts the payload arrives as an
external text/css stylesheet and never executes (no script breakout, no
window flag set). It fails against the old inline rendering.
Bust the stylesheet cache key with the repo's millisecond :epoch format
so two saves within the same second still produce distinct URLs — the
five-minute public cache would otherwise pin the first save.
Jeremy Daer
Kevin McConnell