feat(security): accept the auth cookie and guard against CSRF

Core reads the login token from the tbp_access cookie or a Bearer
header, whichever verifies, and parses it once per request. Unsafe
requests need an X-TBP-Client or Authorization header, CORS allows
only the exact frontend origin, and a missing or expired token
answers 401 instead of 403.

readme.md

@@ -37,8 +37,10 @@ To Be Played is split into three repositories:
 
 Core never issues tokens. It verifies Auth's EdDSA (Ed25519) JWTs with public keys only. It loads them from Auth's
 JWKS by the token's `kid` and loads again when a new `kid` shows up (at most every 10 seconds). Loaded keys stay
-until Core restarts. `JWT_PUBLIC_KEY` is used only until the first JWKS load works. Core reads `userId` and
-`steamId` from the claims.
+until Core restarts. `JWT_PUBLIC_KEY` is used only until the first JWKS load works. The token comes from Auth's
+`tbp_access` cookie or a `Bearer` header, whichever verifies first. Core reads `userId` and `steamId` from the claims.
+`POST`, `PUT` and `DELETE` need an `X-TBP-Client` or `Authorization` header (CSRF guard), and CORS allows only the
+frontend origin.
 A token with a `typ` claim (for example a profile ticket) is rejected on normal endpoints; the profile ticket is
 accepted only by `GET /api/public/profiles/library` in the `X-Profile-Ticket` header.
 

src/main/java/core_service/configuration/security/AccessTokens.java

@@ -0,0 +1,41 @@
+package core_service.configuration.security;
+
+import jakarta.servlet.http.Cookie;
+import jakarta.servlet.http.HttpServletRequest;
+
+import java.util.Arrays;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+/**
+ * Where a request can carry the login token: the access cookie that Auth sets, or a Bearer header (API clients and
+ * tests). Both are tried; a stale cookie next to a valid header must not block the request.
+ */
+final class AccessTokens {
+
+    static final String ACCESS_COOKIE = "tbp_access";
+    private static final String BEARER = "Bearer ";
+
+    private AccessTokens() {
+    }
+
+    static Stream<String> candidates(HttpServletRequest request) {
+        return Stream.of(cookie(request), bearer(request)).flatMap(Optional::stream);
+    }
+
+    private static Optional<String> cookie(HttpServletRequest request) {
+        Cookie[] cookies = request.getCookies();
+        if (cookies == null) {
+            return Optional.empty();
+        }
+        return Arrays.stream(cookies)
+                .filter(cookie -> ACCESS_COOKIE.equals(cookie.getName()) && !cookie.getValue().isBlank())
+                .map(Cookie::getValue)
+                .findFirst();
+    }
+
+    private static Optional<String> bearer(HttpServletRequest request) {
+        String header = request.getHeader("Authorization");
+        return header != null && header.startsWith(BEARER) ? Optional.of(header.substring(BEARER.length())) : Optional.empty();
+    }
+}

src/main/java/core_service/configuration/security/ClientHeaderFilter.java

@@ -0,0 +1,41 @@
+package core_service.configuration.security;
+
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.NonNull;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import java.io.IOException;
+import java.util.Set;
+
+/**
+ * CSRF guard for the login cookie. A request that changes data must carry {@code X-TBP-Client} or
+ * {@code Authorization}. A page on another origin can send neither without a CORS preflight, and CORS allows only
+ * our own origins.
+ */
+public class ClientHeaderFilter extends OncePerRequestFilter {
+
+    public static final String CLIENT_HEADER = "X-TBP-Client";
+    private static final Set<String> SAFE_METHODS = Set.of("GET", "HEAD", "OPTIONS");
+
+    @Override
+    protected void doFilterInternal(
+            @NonNull HttpServletRequest request,
+            @NonNull HttpServletResponse response,
+            @NonNull FilterChain filterChain
+    ) throws ServletException, IOException {
+        if (SAFE_METHODS.contains(request.getMethod())
+                || request.getHeader(CLIENT_HEADER) != null
+                || request.getHeader("Authorization") != null) {
+            filterChain.doFilter(request, response);
+            return;
+        }
+        response.setStatus(HttpStatus.FORBIDDEN.value());
+        response.setContentType(MediaType.APPLICATION_JSON_VALUE);
+        response.getWriter().write("{\"code\":\"CLIENT_HEADER_MISSING\",\"message\":\"Missing X-TBP-Client header\"}");
+    }
+}

src/main/java/core_service/configuration/security/DevJwtAuthenticationFilter.java

@@ -17,6 +17,7 @@ import org.springframework.web.filter.OncePerRequestFilter;
 
 import java.io.IOException;
 import java.util.Collections;
+import java.util.Optional;
 
 /**
  * Dev profile authentication filter.
@@ -56,28 +57,11 @@ public class DevJwtAuthenticationFilter extends OncePerRequestFilter {
         filterChain.doFilter(request, response);
     }
 
-    private java.util.Optional<UserPrincipal> principalFromJwt(HttpServletRequest request) {
-        String authHeader = request.getHeader("Authorization");
-        if (authHeader == null || !authHeader.startsWith("Bearer ")) {
-            return java.util.Optional.empty();
-        }
-        String jwt = authHeader.substring(7);
-        if (!jwtService.isTokenValid(jwt)) {
-            log.debug("Dev mode: invalid JWT, falling back to dummy principal");
-            return java.util.Optional.empty();
-        }
-        try {
-            String email = jwtService.extractEmail(jwt);
-            String userId = jwtService.extractUserId(jwt);
-            Long steamId = jwtService.extractSteamId(jwt);
-            if (email == null || userId == null) {
-                return java.util.Optional.empty();
-            }
-            return java.util.Optional.of(new UserPrincipal(userId, email, steamId));
-        } catch (Exception e) {
-            log.warn("Dev mode: JWT parsing failed: {}", e.getMessage());
-            return java.util.Optional.empty();
-        }
+    private Optional<UserPrincipal> principalFromJwt(HttpServletRequest request) {
+        return AccessTokens.candidates(request)
+                .map(jwtService::parseLoginToken)
+                .flatMap(Optional::stream)
+                .findFirst();
     }
 
     private UserPrincipal dummyPrincipal() {

src/main/java/core_service/configuration/security/JwtAuthenticationFilter.java

@@ -6,7 +6,6 @@ import jakarta.servlet.ServletException;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import lombok.RequiredArgsConstructor;
-import lombok.extern.slf4j.Slf4j;
 import org.jspecify.annotations.NonNull;
 import org.springframework.context.annotation.Profile;
 import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
@@ -17,11 +16,11 @@ import org.springframework.web.filter.OncePerRequestFilter;
 
 import java.io.IOException;
 import java.util.Collections;
+import java.util.Optional;
 
 @Component("jwtAuthenticationFilter")
 @Profile("!dev")
 @RequiredArgsConstructor
-@Slf4j
 public class JwtAuthenticationFilter extends OncePerRequestFilter {
 
     private final JwtService jwtService;
@@ -33,38 +32,19 @@ public class JwtAuthenticationFilter extends OncePerRequestFilter {
             @NonNull FilterChain filterChain
     ) throws ServletException, IOException {
 
-        final String authHeader = request.getHeader("Authorization");
-
-        if (authHeader == null || !authHeader.startsWith("Bearer ")) {
-            filterChain.doFilter(request, response);
-            return;
-        }
-
-        final String jwt = authHeader.substring(7);
-        if (!jwtService.isTokenValid(jwt)) {
-            filterChain.doFilter(request, response);
-            return;
-        }
-
-        try {
-            final String userEmail = jwtService.extractEmail(jwt);
-            final String userId = jwtService.extractUserId(jwt);
-            final Long steamId = jwtService.extractSteamId(jwt);
-
-            if (userEmail != null && userId != null && SecurityContextHolder.getContext().getAuthentication() == null) {
-
-                UserPrincipal principal = new UserPrincipal(userId, userEmail, steamId);
+        Optional<UserPrincipal> principal = AccessTokens.candidates(request)
+                .map(jwtService::parseLoginToken)
+                .flatMap(Optional::stream)
+                .findFirst();
+        if (principal.isPresent() && SecurityContextHolder.getContext().getAuthentication() == null) {
             UsernamePasswordAuthenticationToken authToken = new UsernamePasswordAuthenticationToken(
-                        principal,
+                    principal.get(),
                     null,
                     Collections.emptyList()
             );
             authToken.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
             SecurityContextHolder.getContext().setAuthentication(authToken);
         }
-        } catch (Exception e) {
-            log.error("JWT Validation failed: {}", e.getMessage());
-        }
 
         filterChain.doFilter(request, response);
     }

src/main/java/core_service/configuration/security/JwtService.java

@@ -1,6 +1,7 @@
 package core_service.configuration.security;
 
 import core_service.shared.security.ProfileTicketVerifier;
+import core_service.shared.security.UserPrincipal;
 import io.jsonwebtoken.Claims;
 import io.jsonwebtoken.JwtParser;
 import io.jsonwebtoken.Jwts;
@@ -14,7 +15,7 @@ import java.util.Optional;
 @Service
 public class JwtService implements ProfileTicketVerifier {
 
-    // Only non-login tokens carry this claim; isTokenValid rejects them.
+    // Only non-login tokens carry this claim; parseLoginToken rejects them.
     private static final String TYPE_CLAIM = "typ";
     private static final String PROFILE_TICKET_TYPE = "public-profile";
 
@@ -28,27 +29,20 @@ public class JwtService implements ProfileTicketVerifier {
         return parser.parseSignedClaims(token).getPayload();
     }
 
-    public String extractEmail(String token) {
-        return claims(token).getSubject();
-    }
-
-    public String extractUserId(String token) {
-        return claims(token).get("userId", String.class);
-    }
-
-    public Long extractSteamId(String token) {
-        return claims(token).get("steamId", Long.class);
-    }
-
     /**
-     * True for a login token with a valid signature. A profile ticket is signed with the same key, but is no login.
+     * The user of a login token with a valid signature. Empty for anything else, also for a profile ticket: it is
+     * signed with the same key, but is no login.
      */
-    public boolean isTokenValid(String token) {
+    public Optional<UserPrincipal> parseLoginToken(String token) {
         try {
             Claims claims = claims(token);
-            return claims.get(TYPE_CLAIM) == null;
+            String userId = claims.get("userId", String.class);
+            if (claims.get(TYPE_CLAIM) != null || claims.getSubject() == null || userId == null) {
+                return Optional.empty();
+            }
+            return Optional.of(new UserPrincipal(userId, claims.getSubject(), claims.get("steamId", Long.class)));
         } catch (Exception e) {
-            return false;
+            return Optional.empty();
         }
     }
 

src/main/java/core_service/configuration/security/SecurityConfig.java

@@ -6,17 +6,21 @@ import org.springframework.beans.factory.annotation.Value;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
 import org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer;
 import org.springframework.security.config.http.SessionCreationPolicy;
 import org.springframework.security.web.SecurityFilterChain;
+import org.springframework.security.web.authentication.HttpStatusEntryPoint;
 import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;
 import org.springframework.web.cors.CorsConfiguration;
 import org.springframework.web.cors.CorsConfigurationSource;
 import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
+import org.springframework.web.filter.CorsFilter;
 import org.springframework.web.filter.OncePerRequestFilter;
 
+import java.time.Duration;
 import java.util.Arrays;
 import java.util.List;
 
@@ -43,10 +47,13 @@ public class SecurityConfig {
     @Bean
     public CorsConfigurationSource corsConfigurationSource() {
         CorsConfiguration configuration = new CorsConfiguration();
-        configuration.setAllowedOriginPatterns(Arrays.asList(allowedOrigins));
+        // Exact origins only: with credentials, a pattern would send the login cookie to every matching site.
+        configuration.setAllowedOrigins(Arrays.asList(allowedOrigins));
         configuration.setAllowedMethods(List.of("GET", "POST", "PUT", "DELETE", "OPTIONS"));
-        configuration.setAllowedHeaders(List.of("*"));
-        configuration.setAllowCredentials(false);
+        configuration.setAllowedHeaders(List.of(
+                "Content-Type", "Authorization", ClientHeaderFilter.CLIENT_HEADER, "X-Profile-Ticket"));
+        configuration.setAllowCredentials(true);
+        configuration.setMaxAge(Duration.ofHours(1));
 
         UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
         source.registerCorsConfiguration("/**", configuration);
@@ -59,11 +66,14 @@ public class SecurityConfig {
                 .csrf(AbstractHttpConfigurer::disable)
                 .cors(cors -> cors.configurationSource(corsConfigurationSource()))
                 .sessionManagement(session -> session.sessionCreationPolicy(SessionCreationPolicy.STATELESS))
+                // 401, not Spring's default 403: the frontend renews the access cookie only on a 401.
+                .exceptionHandling(e -> e.authenticationEntryPoint(new HttpStatusEntryPoint(HttpStatus.UNAUTHORIZED)))
                 .authorizeHttpRequests(auth -> auth
                         .requestMatchers(WHITE_LIST_URLS).permitAll()
                         .requestMatchers(HttpMethod.OPTIONS, "/**").permitAll()
                         .anyRequest().authenticated()
                 )
+                .addFilterAfter(new ClientHeaderFilter(), CorsFilter.class)
                 .addFilterBefore(jwtAuthFilter, UsernamePasswordAuthenticationFilter.class);
 
         return http.build();

src/test/java/core_service/configuration/security/AccessTokenFiltersTest.java

@@ -0,0 +1,100 @@
+package core_service.configuration.security;
+
+import core_service.shared.security.UserPrincipal;
+import core_service.shared.test.AbstractUnitTest;
+import jakarta.servlet.http.Cookie;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mock;
+import org.springframework.mock.web.MockFilterChain;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.mockito.Mockito.lenient;
+
+/**
+ * Both login filters take the token from the access cookie or the Bearer header, the first one that verifies.
+ */
+class AccessTokenFiltersTest extends AbstractUnitTest {
+
+    private static final UserPrincipal USER = new UserPrincipal("42", "a@b.de", 76561198000000042L);
+
+    @Mock
+    private JwtService jwtService;
+
+    @AfterEach
+    void clearContext() {
+        SecurityContextHolder.clearContext();
+    }
+
+    private Object principalAfter(jakarta.servlet.Filter filter, MockHttpServletRequest request) throws Exception {
+        filter.doFilter(request, new MockHttpServletResponse(), new MockFilterChain());
+        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+        return authentication == null ? null : authentication.getPrincipal();
+    }
+
+    private void validToken(String token) {
+        lenient().when(jwtService.parseLoginToken(token)).thenReturn(Optional.of(USER));
+    }
+
+    @Test
+    void cookieAuthenticates() throws Exception {
+        validToken("good");
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.setCookies(new Cookie(AccessTokens.ACCESS_COOKIE, "good"));
+
+        assertEquals(USER, principalAfter(new JwtAuthenticationFilter(jwtService), request));
+    }
+
+    @Test
+    void bearerAuthenticates() throws Exception {
+        validToken("good");
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.addHeader("Authorization", "Bearer good");
+
+        assertEquals(USER, principalAfter(new JwtAuthenticationFilter(jwtService), request));
+    }
+
+    @Test
+    void staleCookieFallsBackToTheBearerHeader() throws Exception {
+        validToken("good");
+        lenient().when(jwtService.parseLoginToken("stale")).thenReturn(Optional.empty());
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.setCookies(new Cookie(AccessTokens.ACCESS_COOKIE, "stale"));
+        request.addHeader("Authorization", "Bearer good");
+
+        assertEquals(USER, principalAfter(new JwtAuthenticationFilter(jwtService), request));
+    }
+
+    @Test
+    void invalidTokenStaysAnonymous() throws Exception {
+        lenient().when(jwtService.parseLoginToken("bad")).thenReturn(Optional.empty());
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.setCookies(new Cookie(AccessTokens.ACCESS_COOKIE, "bad"));
+
+        assertNull(principalAfter(new JwtAuthenticationFilter(jwtService), request));
+    }
+
+    @Test
+    void devFilter_UsesTheCookieUser() throws Exception {
+        validToken("good");
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.setCookies(new Cookie(AccessTokens.ACCESS_COOKIE, "good"));
+
+        assertEquals(USER, principalAfter(new DevJwtAuthenticationFilter(jwtService), request));
+    }
+
+    @Test
+    void devFilter_WithoutTokenUsesTheDummyUser() throws Exception {
+        UserPrincipal principal = (UserPrincipal) principalAfter(new DevJwtAuthenticationFilter(jwtService),
+                new MockHttpServletRequest());
+
+        assertEquals("1", principal.id());
+    }
+}

src/test/java/core_service/configuration/security/ClientHeaderFilterTest.java

@@ -0,0 +1,56 @@
+package core_service.configuration.security;
+
+import core_service.shared.test.AbstractIntegrationTest;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.webmvc.test.autoconfigure.AutoConfigureMockMvc;
+import org.springframework.test.web.servlet.MockMvc;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.options;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.header;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+/**
+ * The dev profile logs every request in, so only the CSRF header and CORS decide here.
+ */
+@AutoConfigureMockMvc
+class ClientHeaderFilterTest extends AbstractIntegrationTest {
+
+    private static final String FRONTEND = "https://tbp.andreas-dahm.eu";
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Test
+    void postWithoutClientHeader_Is403() throws Exception {
+        mockMvc.perform(post("/api/library/sync"))
+                .andExpect(status().isForbidden())
+                .andExpect(jsonPath("$.code").value("CLIENT_HEADER_MISSING"));
+    }
+
+    @Test
+    void postWithClientHeader_PassesTheFilter() throws Exception {
+        int status = mockMvc.perform(post("/api/library/sync").header(ClientHeaderFilter.CLIENT_HEADER, "test"))
+                .andReturn().getResponse().getStatus();
+
+        org.junit.jupiter.api.Assertions.assertNotEquals(403, status);
+    }
+
+    @Test
+    void corsPreflight_AllowsOnlyTheFrontendWithCookies() throws Exception {
+        mockMvc.perform(options("/api/library/sync")
+                        .header("Origin", FRONTEND)
+                        .header("Access-Control-Request-Method", "POST")
+                        .header("Access-Control-Request-Headers", "x-tbp-client"))
+                .andExpect(status().isOk())
+                .andExpect(header().string("Access-Control-Allow-Origin", FRONTEND))
+                .andExpect(header().string("Access-Control-Allow-Credentials", "true"));
+
+        mockMvc.perform(options("/api/library/sync")
+                        .header("Origin", "https://evil.andreas-dahm.eu")
+                        .header("Access-Control-Request-Method", "POST"))
+                .andExpect(status().isForbidden());
+    }
+}

src/test/java/core_service/configuration/security/ExpiredAccessTokenTest.java

@@ -0,0 +1,42 @@
+package core_service.configuration.security;
+
+import core_service.shared.test.AbstractIntegrationTest;
+import jakarta.servlet.http.Cookie;
+import io.jsonwebtoken.Jwts;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.webmvc.test.autoconfigure.AutoConfigureMockMvc;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.web.servlet.MockMvc;
+
+import java.util.Date;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+/**
+ * The real (non-dev) filter chain, where the token decides.
+ */
+@AutoConfigureMockMvc
+@ActiveProfiles(value = "prod", inheritProfiles = false)
+class ExpiredAccessTokenTest extends AbstractIntegrationTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    private static String expiredAccessToken() {
+        return Jwts.builder()
+                .subject("a@b.de")
+                .claim("userId", "42")
+                .issuedAt(new Date(System.currentTimeMillis() - 120_000))
+                .expiration(new Date(System.currentTimeMillis() - 60_000))
+                .signWith(TEST_KEYS.getPrivate(), Jwts.SIG.EdDSA)
+                .compact();
+    }
+
+    @Test
+    void expiredAccessCookie_Is401SoTheFrontendRefreshes() throws Exception {
+        mockMvc.perform(get("/api/library/summary").cookie(new Cookie(AccessTokens.ACCESS_COOKIE, expiredAccessToken())))
+                .andExpect(status().isUnauthorized());
+    }
+}

src/test/java/core_service/configuration/security/JwtServiceTest.java

@@ -1,5 +1,6 @@
 package core_service.configuration.security;
 
+import core_service.shared.security.UserPrincipal;
 import core_service.shared.test.AbstractUnitTest;
 import io.jsonwebtoken.Jwts;
 import org.junit.jupiter.api.BeforeEach;
@@ -54,51 +55,40 @@ class JwtServiceTest extends AbstractUnitTest {
     }
 
     @Test
-    void extractEmail_Success() {
-        var email = "test@example.com";
-        var token = signToken("0815", email, null);
+    void parseLoginToken_ReturnsTheUser() {
+        String token = signToken("0815", "test@example.com", 123456789L);
 
-        assertEquals(email, jwtService.extractEmail(token));
+        assertEquals(Optional.of(new UserPrincipal("0815", "test@example.com", 123456789L)),
+                jwtService.parseLoginToken(token));
     }
 
     @Test
-    void extractUserId_Success() {
-        var userId = "0815";
-        var token = signToken(userId, "test@example.com", null);
-
-        assertEquals(userId, jwtService.extractUserId(token));
+    void parseLoginToken_RejectsGarbage() {
+        assertEquals(Optional.empty(), jwtService.parseLoginToken("not-a-jwt"));
     }
 
     @Test
-    void extractSteamId_Success() {
-        var steamId = 123456789L;
-        var token = signToken("0815", "test@example.com", steamId);
-
-        assertEquals(steamId, jwtService.extractSteamId(token));
-    }
-
-    @Test
-    void isTokenValid_Success() {
-        var token = signToken("0815", "test@example.com", null);
-
-        assertTrue(jwtService.isTokenValid(token));
-    }
-
-    @Test
-    void isTokenValid_Failure_garbage() {
-        assertFalse(jwtService.isTokenValid("not-a-jwt"));
-    }
-
-    @Test
-    void isTokenValid_Failure_wrongKey() throws Exception {
+    void parseLoginToken_RejectsAForeignKey() throws Exception {
         KeyPair other = KeyPairGenerator.getInstance("Ed25519").generateKeyPair();
         String token = Jwts.builder()
                 .subject("test@example.com")
+                .claim("userId", "0815")
                 .expiration(new Date(System.currentTimeMillis() + 60_000))
                 .signWith(other.getPrivate(), Jwts.SIG.EdDSA)
                 .compact();
 
-        assertFalse(jwtService.isTokenValid(token));
+        assertEquals(Optional.empty(), jwtService.parseLoginToken(token));
+    }
+
+    @Test
+    void parseLoginToken_RejectsATokenWithoutUserId() {
+        String token = Jwts.builder()
+                .subject("test@example.com")
+                .expiration(new Date(System.currentTimeMillis() + 60_000))
+                .signWith(signingKey, Jwts.SIG.EdDSA)
+                .compact();
+
+        assertEquals(Optional.empty(), jwtService.parseLoginToken(token));
     }
 
     private String signTicket(String type, String profileUserId, long expiresInMs) {
@@ -130,7 +120,7 @@ class JwtServiceTest extends AbstractUnitTest {
     }
 
     @Test
-    void isTokenValid_ProfileTicketIsNoLogin() {
-        assertFalse(jwtService.isTokenValid(signTicket("public-profile", "42", 60_000)));
+    void parseLoginToken_ProfileTicketIsNoLogin() {
+        assertEquals(Optional.empty(), jwtService.parseLoginToken(signTicket("public-profile", "42", 60_000)));
     }
 }

src/test/java/core_service/modules/library/api/LibraryControllerBacklogTest.java

@@ -7,6 +7,7 @@ import core_service.modules.library.domain.UserGame;
 import core_service.modules.library.domain.UserGameId;
 import core_service.modules.library.repo.SteamGameRepository;
 import core_service.modules.library.repo.UserGameRepository;
+import core_service.configuration.security.ClientHeaderFilter;
 import core_service.shared.test.AbstractIntegrationTest;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -56,7 +57,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
 
     @Test
     void updateBacklog_StoresAllFields() throws Exception {
-        mockMvc.perform(put("/api/library/games/220/backlog").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/backlog").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"FINISHED\",\"rating\":4,\"notes\":\"Great ending\",\"priority\":\"HIGH\"}"))
                 .andExpect(status().isOk())
                 .andExpect(jsonPath("$.status").value("FINISHED"))
@@ -76,7 +77,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
         game.setNotes("old");
         userGameRepository.save(game);
 
-        mockMvc.perform(put("/api/library/games/220/backlog").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/backlog").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"DROPPED\",\"notes\":\"   \"}"))
                 .andExpect(status().isOk());
 
@@ -95,7 +96,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
             "{\"status\":\"PLAYING\",\"rating\":6}",
             "{\"status\":\"PLAYING\",\"priority\":\"URGENT\"}"})
     void updateBacklog_InvalidBody_Is400AndStoresNothing(String body) throws Exception {
-        mockMvc.perform(put("/api/library/games/220/backlog").contentType(MediaType.APPLICATION_JSON).content(body))
+        mockMvc.perform(put("/api/library/games/220/backlog").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON).content(body))
                 .andExpect(status().isBadRequest());
 
         assertEquals(GameStatus.BACKLOG, stored().getStatus());
@@ -103,7 +104,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
 
     @Test
     void updateBacklog_FractionalRating_Is400() throws Exception {
-        mockMvc.perform(put("/api/library/games/220/backlog").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/backlog").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"PLAYING\",\"rating\":4.7}"))
                 .andExpect(status().isBadRequest());
 
@@ -113,7 +114,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
     @Test
     void updateBacklog_NotesTooLong_Is400() throws Exception {
         String notes = "x".repeat(2001);
-        mockMvc.perform(put("/api/library/games/220/backlog").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/backlog").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"PLAYING\",\"notes\":\"" + notes + "\"}"))
                 .andExpect(status().isBadRequest());
     }
@@ -124,7 +125,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
         game.setRemovedAt(Instant.now());
         userGameRepository.save(game);
 
-        mockMvc.perform(put("/api/library/games/220/backlog").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/backlog").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"PLAYING\"}"))
                 .andExpect(status().isNotFound())
                 .andExpect(jsonPath("$.code").value("GAME_NOT_FOUND"));
@@ -132,7 +133,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
 
     @Test
     void updateBacklog_GameNotOwned_Is404() throws Exception {
-        mockMvc.perform(put("/api/library/games/999/backlog").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/999/backlog").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"PLAYING\"}"))
                 .andExpect(status().isNotFound());
     }
@@ -145,7 +146,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
         game.setPriority(GamePriority.HIGH);
         userGameRepository.save(game);
 
-        mockMvc.perform(put("/api/library/games/220/status").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/status").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"PLAYING\"}"))
                 .andExpect(status().isOk())
                 .andExpect(jsonPath("$.status").value("PLAYING"))
@@ -160,7 +161,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
 
     @Test
     void updateStatus_MissingStatus_Is400() throws Exception {
-        mockMvc.perform(put("/api/library/games/220/status").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/status").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{}"))
                 .andExpect(status().isBadRequest());
 
@@ -173,7 +174,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
         game.setRemovedAt(Instant.now());
         userGameRepository.save(game);
 
-        mockMvc.perform(put("/api/library/games/220/status").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/220/status").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"PLAYING\"}"))
                 .andExpect(status().isNotFound())
                 .andExpect(jsonPath("$.code").value("GAME_NOT_FOUND"));
@@ -181,7 +182,7 @@ class LibraryControllerBacklogTest extends AbstractIntegrationTest {
 
     @Test
     void updateStatus_GameNotOwned_Is404() throws Exception {
-        mockMvc.perform(put("/api/library/games/999/status").contentType(MediaType.APPLICATION_JSON)
+        mockMvc.perform(put("/api/library/games/999/status").header(ClientHeaderFilter.CLIENT_HEADER, "test").contentType(MediaType.APPLICATION_JSON)
                         .content("{\"status\":\"PLAYING\"}"))
                 .andExpect(status().isNotFound());
     }