From be23baa816f68939ef599860dd37072fd4116be5 Mon Sep 17 00:00:00 2001
From: "dobby-yivi-agent[bot]"
 <275734547+dobby-yivi-agent[bot]@users.noreply.github.com>
Date: Mon, 11 May 2026 19:59:50 +0000
Subject: [PATCH] security: add baseline security headers to nginx config

Adds Strict-Transport-Security, X-Content-Type-Options, X-Frame-Options,
Referrer-Policy, and a minimal frame-ancestors Content-Security-Policy
to the server block. Headers are repeated in the cache-control and
/health locations because nginx add_header inheritance is
replace-not-merge per location.

Closes #74
---
 nginx.conf | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/nginx.conf b/nginx.conf
index 5e50b25..fb848c9 100644
--- a/nginx.conf
+++ b/nginx.conf
@@ -4,9 +4,20 @@ server {
     root /usr/share/nginx/html;
     index index.html;
 
+    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+    add_header X-Content-Type-Options "nosniff" always;
+    add_header X-Frame-Options "DENY" always;
+    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+    add_header Content-Security-Policy "frame-ancestors 'none'" always;
+
     location /health {
         return 200 "healthy\n";
         add_header Content-Type text/plain;
+        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+        add_header X-Content-Type-Options "nosniff" always;
+        add_header X-Frame-Options "DENY" always;
+        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+        add_header Content-Security-Policy "frame-ancestors 'none'" always;
     }
 
     location / {
@@ -17,6 +28,11 @@ server {
     location ~* \.(js|css|woff2?|ttf|svg|png|jpg|ico)$ {
         expires 1y;
         add_header Cache-Control "public, immutable";
+        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
+        add_header X-Content-Type-Options "nosniff" always;
+        add_header X-Frame-Options "DENY" always;
+        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+        add_header Content-Security-Policy "frame-ancestors 'none'" always;
     }
 
     gzip on;