An expired-auth 401 on the login page fed the login redirect its own address:
each of the three redirect guards (_safeNextPath in login.js,
_safe_login_redirect_path in routes.py, the api() 401 redirect in workspace.js,
_safe_login_inner_next in auth.py) validated against open-redirect but none
rejected a `next` pointing back at the login page, so every auth bounce wrapped +
re-encoded the previous login URL one level deeper — growing the URL exponentially
until the browser's length limit broke the tab. All guards now collapse/reject a
`next` whose decoded leading PATH resolves to the login route (bounded
percent-decoding up to 8 levels, fail-closed at the cap), while preserving the
existing open-redirect protections AND legitimate non-login paths that merely
carry their own `next=` query key. Length cap as belt-and-suspenders.
Self-built (nesquena-hermes); nesquena independent review APPROVED. Gate (Codex)
found + fixed an over-broad nested-next reject (regressed next-carrying paths) and
a deep-encode decode off-by-one; both root-fixed, login guards verified clean.
nesquena-hermes
e09e819f08