add_header is non-additive: any location declaring its own add_header
drops all server-context headers. archive.conf already re-included the
baseline for exactly this reason, but static-assets.conf (four cache
locations — including the JS/CSS responses where nosniff matters most)
and popup-proxy.conf (three proxy locations) did not. All seven now
re-include snippets/security-headers.conf.
Proxy locations additionally hide the upstream's own
STS/CSP/X-Frame-Options before re-adding ours: browsers honor only the
FIRST Strict-Transport-Security header (RFC 6797 §8.1), so arXiv's
max-age=300 passing through ahead of ours would have downgraded the
domain's cached HSTS policy on every popup fetch.
Server side (installed + verified live): security-headers.conf and
archive.conf wired into the vhost in vhost.conf.example's canonical
order; nginx-mod-brotli installed and loaded, so the .br sidecars
compress-assets.sh has always shipped are now actually served
(Content-Encoding: br verified). CSP remains Report-Only. Verified
headers on /, /css/*.css (baseline + Cache-Control together),
/archive/ (baseline + X-Robots-Tag), and /proxy/* (baseline +
X-Cache-Status, single STS).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
- Add nginx/security-headers.conf — server_tokens off, HSTS (1y +
preload), X-Content-Type-Options, X-Frame-Options DENY,
Referrer-Policy, Permissions-Policy, and a usage-scoped CSP. CSP
ships in Report-Only mode; promote to enforcing once the report
stream is clean for a week. CSP allowlists are derived from actual
usage (cdn.jsdelivr.net for KaTeX/Vega, *.basemaps.cartocdn.com for
Leaflet tiles); 'unsafe-inline' and 'unsafe-eval' are documented
inline.
- Add nginx/vhost.conf.example — reference vhost showing the canonical
include order. The live vhost on the VPS remains the source of
truth; this file documents the structure so the VPS config can be
reproduced or audited from the repo.
- Shorten unfingerprinted CSS/JS cache from 24h to 1h. Bug fixes ship
to warm clients within an hour; if assets are ever fingerprinted,
this can move to immutable.
- Refresh README repo layout — add nginx/ entry, drop stale paper/
and spec.md references that never existed in the working tree.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Levi Neuwirth