Spring Security 7.1 JWT authentication on Spring Boot 4.1

Runnable companion for https://ankurm.com/spring-security-7-1-jwt-authentication-guide/

- login -> token issue -> OncePerRequestFilter -> SecurityContext, end to end
- HS256 and RS256 variants (RS256 publishes a real JWKS endpoint)
- the same API secured by the built-in oauth2ResourceServer().jwt(), for comparison
- 11 documentation chapters under docs/, interlinked with the code
- docs/output/ is real captured output, regenerated by scripts/run-all.sh
- 13 passing tests pinning the 401-vs-403 contract and the CSRF failure

Verified against Spring Boot 4.1.1, Spring Security 7.1.1, JDK 25.0.4.1.

scripts/run.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# Starts the app on a clean port 8080 with the given profiles.
+# Usage: ./scripts/run.sh [profiles]   e.g. ./scripts/run.sh rs256,resourceserver
+set -eu
+PROFILES="${1:-hs256}"
+for p in $(ps -eo pid,cmd | grep '[J]wtAuthDemoApplication' | awk '{print $1}'); do kill -9 "$p" || true; done
+sleep 2
+setsid nohup mvn -B -o org.springframework.boot:spring-boot-maven-plugin:run \
+  -Dspring-boot.run.profiles="$PROFILES" > "/tmp/app-${PROFILES//,/-}.log" 2>&1 < /dev/null &
+for i in $(seq 1 60); do
+  if curl -s -o /dev/null http://localhost:8080/api/public/ping 2>/dev/null; then
+    echo "started with profiles: $PROFILES"; exit 0
+  fi
+  sleep 2
+done
+echo "failed to start; see /tmp/app-${PROFILES//,/-}.log" >&2; exit 1