diff --git a/deploy/varnish/default.vcl.template b/deploy/varnish/default.vcl.template
index adf68a9..6bb7cff 100644
--- a/deploy/varnish/default.vcl.template
+++ b/deploy/varnish/default.vcl.template
@@ -3,52 +3,57 @@ vcl 4.1;
 import vsthrottle;
 import std;
 
-# ===== Backend =====
 backend app {
   .host = "app";
   .port = "${APP_PORT}";
 }
 
-# ===== ACL =====
 acl purge {
   "127.0.0.1";
   "::1";
 }
 
-# ===== RECV =====
 sub vcl_recv {
-  # RATE LIMIT: 200 żądań / 10s, blokada 60s
+  # Do not trust client-supplied internal state headers.
+  unset req.http.X-RFC9211-State;
+  unset req.http.X-RFC9211-Entry;
+  unset req.http.X-RFC9211-TTL;
+
   if (vsthrottle.is_denied(client.identity, 200, 10s, 60s)) {
     return (synth(429, "Too Many Requests"));
   }
 
-  # PURGE tylko lokalnie
   if (req.method == "PURGE") {
-    if (!client.ip ~ purge) { return (synth(405, "Not allowed")); }
+    if (!client.ip ~ purge) {
+      return (synth(405, "Not allowed"));
+    }
     return (purge);
   }
 
-  # omijamy cache dla healthchecków / wewnętrznych nagłówków
-  if (req.url == "/healthcheck" || req.http.X-Internal-Check) { return (pass); }
-
-  # WebSocket wymaga surowego tunelu TCP, ale zwykły transport polling
-  # Socket.IO jest normalnym HTTP i nie może trafiać do pipe. Puszczenie całego
-  # /socket.io/ przez pipe może pozostawić połączenie HTTP przypięte do backendu
-  # po uśpieniu mobilnej przeglądarki i utrudniać późniejszy refresh/nawigację.
-  if (req.http.Upgrade ~ "(?i)websocket") {
-    return (pipe);
+  if (!req.http.X-Forwarded-Proto) {
+    set req.http.X-Forwarded-Proto = "https";
   }
-  if (req.url ~ "^/socket.io/") {
+
+  if (req.url ~ "^/healthcheck(\?.*)?$" || req.http.X-Internal-Check) {
     return (pass);
   }
 
-  # metody inne niż GET/HEAD bez cache
-  if (req.method != "GET" && req.method != "HEAD") { return (pass); }
+  # Only WebSocket upgrades use pipe, never Socket.IO polling.
+  if (req.http.Upgrade ~ "(?i)websocket") {
+    return (pipe);
+  }
+  if (req.url ~ "^/socket\.io/") {
+    return (pass);
+  }
 
-  # Żądania z Authorization nie są buforowane
-  if (req.http.Authorization) { return (pass); }
+  if (req.method != "GET" && req.method != "HEAD") {
+    return (pass);
+  }
+  if (req.http.Authorization) {
+    return (pass);
+  }
 
-  # ---- Normalizacja Accept-Encoding (kolejność: zstd > br > gzip) ----
+  # Preserve the original encoding normalization policy.
   if (req.http.Accept-Encoding) {
     if (req.http.Accept-Encoding ~ "zstd") {
       set req.http.Accept-Encoding = "zstd";
@@ -61,51 +66,16 @@ sub vcl_recv {
     }
   }
 
-  # ---- (Opcjonalnie) Normalizacja Accept dla obrazów generowanych wariantowo ----
-  # if (req.url ~ "\.(png|jpe?g|gif|bmp)$") {
-  #   if (req.http.Accept ~ "image/webp") {
-  #     set req.http.X-Accept-Image = "modern";   # webp
-  #   } else {
-  #     set req.http.X-Accept-Image = "legacy";   # jpg/png
-  #   }
-  # }
-
-  # ---- STATYCZNE – agresywny cache + ignorujemy sesję ----
-  if (req.url ~ "^/static/" || req.url ~ "^/uploads/" || req.url ~ "\.(css|js|png|jpe?g|webp|svg|ico|woff2?)$") {
+  # Cache public static files independently of session cookies.
+  if (req.url ~ "^/(static|uploads)/" ||
+      req.url ~ "(?i)\.(css|js|png|jpe?g|webp|svg|ico|woff2?)(\?.*)?$") {
     unset req.http.Cookie;
-    unset req.http.Authorization;
     return (hash);
   }
 
-  if (!req.http.X-Forwarded-Proto) {
-    set req.http.X-Forwarded-Proto = "https";
-  }
-
-  if (req.url == "/healthcheck" || req.http.X-Internal-Check) {
-    set req.http.X-Pass-Reason = "internal";
-    return (pass);
-  }
-
-  if (req.method != "GET" && req.method != "HEAD") {
-    set req.http.X-Pass-Reason = "method";
-    return (pass);
-  }
-
-  if (req.http.Authorization) {
-    set req.http.X-Pass-Reason = "auth";
-    return (pass);
-  }
-
-  # jeśli chcesz PASS przy cookie:
-  # if (req.http.Cookie) {
-  #   set req.http.X-Pass-Reason = "cookie";
-  #   return (pass);
-  # }
-
   return (hash);
 }
 
-# ===== PIPE (WebSocket passthrough) =====
 sub vcl_pipe {
   if (req.http.Upgrade) {
     set bereq.http.Upgrade = req.http.Upgrade;
@@ -113,41 +83,68 @@ sub vcl_pipe {
   }
 }
 
-# ===== HASH =====
 sub vcl_hash {
   hash_data(req.url);
-  if (req.http.host) { hash_data(req.http.host); } else { hash_data(server.ip); }
-
-  # Cookie: zostają dla dynamicznych (dla statyków wyczyszczone wcześniej)
-  if (req.http.Cookie) { hash_data(req.http.Cookie); }
-
-  # Accept-Encoding: już znormalizowany do zstd/br/gzip/identity
-  if (req.http.Accept-Encoding) { hash_data(req.http.Accept-Encoding); }
-
-  # (Opcjonalnie) sygnał obrazów z negocjacją po Accept
-  if (req.http.X-Accept-Image) { hash_data(req.http.X-Accept-Image); }
+  if (req.http.host) {
+    hash_data(req.http.host);
+  } else {
+    hash_data(server.ip);
+  }
+  if (req.http.Cookie) {
+    hash_data(req.http.Cookie);
+  }
+  if (req.http.Accept-Encoding) {
+    hash_data(req.http.Accept-Encoding);
+  }
+  if (req.http.X-Accept-Image) {
+    hash_data(req.http.X-Accept-Image);
+  }
+}
+
+# These hooks remember how the CURRENT request was handled.
+sub vcl_hit {
+  set req.http.X-RFC9211-State = "hit";
+}
+
+sub vcl_miss {
+  set req.http.X-RFC9211-State = "miss";
+}
+
+sub vcl_pass {
+  if (req.method == "GET" || req.method == "HEAD") {
+    set req.http.X-RFC9211-State = "bypass";
+  } else {
+    set req.http.X-RFC9211-State = "method";
+  }
+}
+
+sub vcl_backend_fetch {
+  # Internal markers must never reach the origin application.
+  unset bereq.http.X-RFC9211-State;
+  unset bereq.http.X-RFC9211-Entry;
+  unset bereq.http.X-RFC9211-TTL;
 }
 
-# ===== BACKEND_RESPONSE =====
 sub vcl_backend_response {
-  # Zakaz cache – respektujemy
-  if (beresp.http.Cache-Control ~ "(?i)no-store|private") {
+  # The synthetic marker belongs only to Varnish, not to the origin.
+  unset beresp.http.X-RFC9211-Synthetic;
+
+  if (beresp.http.Cache-Control ~ "(?i)no-store|private|no-cache" ||
+      beresp.http.Surrogate-Control ~ "(?i)no-store" ||
+      beresp.http.Vary == "*") {
     set beresp.uncacheable = true;
     set beresp.ttl = 0s;
-    set beresp.http.X-Pass-Reason = "no-store";
     return (deliver);
   }
 
-  # NIE cache'uj redirectów do loginu (HTML) z backendu
   if (beresp.status >= 300 && beresp.status < 400) {
     set beresp.uncacheable = true;
     set beresp.ttl = 0s;
-    set beresp.http.X-Pass-Reason = "redirect";
     return (deliver);
   }
 
-  # Nie cache'uj statyków, jeśli status ≠ 200
-  if (bereq.url ~ "^/static/" || bereq.url ~ "^/uploads/" || bereq.url ~ "\.(css|js|png|jpe?g|webp|svg|ico|woff2?)($|\?)") {
+  if (bereq.url ~ "^/(static|uploads)/" ||
+      bereq.url ~ "(?i)\.(css|js|png|jpe?g|webp|svg|ico|woff2?)(\?.*)?$") {
     if (beresp.status != 200) {
       set beresp.uncacheable = true;
       set beresp.ttl = 0s;
@@ -155,121 +152,138 @@ sub vcl_backend_response {
     }
   }
 
-  # Jeśli pod .js przychodzi text/html — też nie cache'uj (to zwykle redirect/login)
-  if (bereq.url ~ "\.js(\?.*)?$" && beresp.http.Content-Type ~ "(?i)text/html") {
+  # An HTML login page returned as a JS/CSS asset must not be cached.
+  if (bereq.url ~ "(?i)\.(js|css)(\?.*)?$" &&
+      beresp.http.Content-Type ~ "(?i)text/html") {
     set beresp.uncacheable = true;
     set beresp.ttl = 0s;
     return (deliver);
   }
 
-  # Wymuś poprawny Content-Type dla .js/.css, gdy backend zwróci HTML
-  if (bereq.url ~ "\.js(\?.*)?$") {
-    if (!beresp.http.Content-Type || beresp.http.Content-Type ~ "(?i)text/html") {
-      set beresp.http.Content-Type = "application/javascript; charset=utf-8";
-    }
+  if (bereq.url ~ "(?i)\.js(\?.*)?$" && !beresp.http.Content-Type) {
+    set beresp.http.Content-Type = "application/javascript; charset=utf-8";
   }
-  if (bereq.url ~ "\.css(\?.*)?$") {
-    if (!beresp.http.Content-Type || beresp.http.Content-Type ~ "(?i)text/html") {
-      set beresp.http.Content-Type = "text/css; charset=utf-8";
-    }
+  if (bereq.url ~ "(?i)\.css(\?.*)?$" && !beresp.http.Content-Type) {
+    set beresp.http.Content-Type = "text/css; charset=utf-8";
   }
 
-  # ---- STATYCZNE: zdejmij Set-Cookie i Vary: Cookie, zapewnij TTL ----
-  if (bereq.url ~ "^/static/" || bereq.url ~ "^/uploads/" || bereq.url ~ "\.(css|js|png|jpe?g|webp|svg|ico|woff2?)$") {
+  if (bereq.url ~ "^/(static|uploads)/" ||
+      bereq.url ~ "(?i)\.(css|js|png|jpe?g|webp|svg|ico|woff2?)(\?.*)?$") {
     unset beresp.http.Set-Cookie;
 
-    # Jeśli backend dodał Vary: Cookie, usuńmy ten element (nie wpływa na statyki)
     if (beresp.http.Vary) {
       set beresp.http.Vary = regsuball(beresp.http.Vary, "(?i)(^|,)[[:space:]]*Cookie[[:space:]]*(,|$)", "\1");
       set beresp.http.Vary = regsuball(beresp.http.Vary, ",[[:space:]]*,", ",");
       set beresp.http.Vary = regsub(beresp.http.Vary, "^[[:space:]]*,[[:space:]]*", "");
       set beresp.http.Vary = regsub(beresp.http.Vary, "[[:space:]]*,[[:space:]]*$", "");
-      if (beresp.http.Vary ~ "^[[:space:]]*$") { unset beresp.http.Vary; }
+      if (beresp.http.Vary ~ "^[[:space:]]*$") {
+        unset beresp.http.Vary;
+      }
     }
 
-    # Jeśli brak kontroli czasu życia – ustawiamy twarde wartości
     if (!(beresp.http.Cache-Control ~ "(?i)(s-maxage|max-age)")) {
       set beresp.ttl = 24h;
       set beresp.http.Cache-Control = "public, max-age=86400, immutable";
     }
 
     set beresp.grace = 1h;
-    set beresp.keep  = 24h;
+    set beresp.keep = 24h;
   }
 
-  # ---- Ogólne TTL z nagłówków ----
   if (beresp.http.Cache-Control ~ "(?i)s-maxage=([0-9]+)") {
     set beresp.ttl = std.duration(regsub(beresp.http.Cache-Control, "(?i).*s-maxage=([0-9]+).*", "\1") + "s", 0s);
   } else if (beresp.http.Cache-Control ~ "(?i)max-age=([0-9]+)") {
     set beresp.ttl = std.duration(regsub(beresp.http.Cache-Control, "(?i).*max-age=([0-9]+).*", "\1") + "s", 0s);
   } else if (beresp.http.Expires) {
     set beresp.ttl = std.time(beresp.http.Expires, now) - now;
-    if (beresp.ttl < 0s) { set beresp.ttl = 0s; }
-  } else {
-    if (beresp.ttl <= 0s) { set beresp.ttl = 60s; }
+    if (beresp.ttl < 0s) {
+      set beresp.ttl = 0s;
+    }
+  } else if (beresp.ttl <= 0s) {
+    set beresp.ttl = 60s;
   }
 
-  # Immutable => dłuższe grace/keep
   if (beresp.http.Cache-Control ~ "(?i)immutable") {
     set beresp.grace = 1h;
-    set beresp.keep  = 24h;
+    set beresp.keep = 24h;
   }
 
-  # Kompresja po stronie Varnisha wyłącznie dla klientów akceptujących gzip
-  # i tylko jeśli backend nie dostarczył już Content-Encoding.
   if (!beresp.http.Content-Encoding && bereq.http.Accept-Encoding ~ "gzip") {
-    # Kompresujemy tylko „tekstowe” typy; wykluczamy WASM
     if (beresp.http.Content-Type ~ "(?i)text/|application/(javascript|json|xml)") {
       set beresp.do_gzip = true;
     }
   }
 
-  # Duże odpowiedzi streamujemy
-  if (beresp.http.Content-Length && std.integer(beresp.http.Content-Length, 0) > 1048576) {
+  if (beresp.http.Content-Length &&
+      std.integer(beresp.http.Content-Length, 0) > 1048576) {
     set beresp.do_stream = true;
   }
 }
 
-# (Opcjonalnie) Serwuj „stale” przy błędach backendu, jeśli jest obiekt w grace
 sub vcl_backend_error {
+  # Do not claim a synthetic backend-fetch error was served by a cache.
+  set beresp.uncacheable = true;
+  set beresp.ttl = 0s;
+  set beresp.http.X-RFC9211-Synthetic = "1";
   return (deliver);
 }
 
-# ===== DELIVER =====
 sub vcl_deliver {
-  if (obj.uncacheable) {
-    if (req.http.X-Pass-Reason) {
-      set resp.http.X-Cache = "PASS:" + req.http.X-Pass-Reason;
-    } else if (resp.http.X-Pass-Reason) {    # z backendu
-      set resp.http.X-Cache = "PASS:" + resp.http.X-Pass-Reason;
-    } else {
-      set resp.http.X-Cache = "PASS";
-    }
-    unset resp.http.X-Pass-Reason;
-    unset resp.http.Age;
-  } else if (obj.hits > 0) {
-    set resp.http.X-Cache = "HIT";
+  if (resp.http.X-RFC9211-Synthetic) {
+    unset resp.http.Cache-Status;
   } else {
-    set resp.http.X-Cache = "MISS";
-    unset resp.http.Age;
+    if (req.http.X-RFC9211-State == "hit") {
+      # DURATION -> STRING works with VCL 4.1 / Varnish 6.0+.
+      # Structured Fields require an integer, not a decimal string.
+      set req.http.X-RFC9211-TTL = obj.ttl;
+      if (obj.ttl < 0s && obj.ttl > -1s) {
+        set req.http.X-RFC9211-TTL = "-1";
+      } else {
+        set req.http.X-RFC9211-TTL = regsub(req.http.X-RFC9211-TTL, "\.[0-9]+$", "");
+      }
+      set req.http.X-RFC9211-Entry = "varnish; hit; ttl=" + req.http.X-RFC9211-TTL;
+    } else if (req.http.X-RFC9211-State == "miss") {
+      set req.http.X-RFC9211-Entry = "varnish; fwd=miss";
+      if (obj.uncacheable) {
+        set req.http.X-RFC9211-Entry = req.http.X-RFC9211-Entry + "; stored=?0";
+      } else {
+        set req.http.X-RFC9211-Entry = req.http.X-RFC9211-Entry + "; stored";
+      }
+    } else if (req.http.X-RFC9211-State == "method") {
+      set req.http.X-RFC9211-Entry = "varnish; fwd=method";
+    } else {
+      set req.http.X-RFC9211-Entry = "varnish; fwd=bypass";
+    }
+
+    # RFC 9211: preserve the cache chain and append our own member LAST.
+    if (resp.http.Cache-Status) {
+      set resp.http.Cache-Status = resp.http.Cache-Status + ", " + req.http.X-RFC9211-Entry;
+    } else {
+      set resp.http.Cache-Status = req.http.X-RFC9211-Entry;
+    }
   }
 
+  unset resp.http.X-RFC9211-Synthetic;
+  unset resp.http.X-Cache;
+  unset resp.http.X-Pass-Reason;
   unset resp.http.Via;
   unset resp.http.X-Varnish;
   unset resp.http.Server;
   unset resp.http.Content-Disposition;
+  # Keep Age: it is useful cache metadata and can reflect upstream age.
 }
 
 sub vcl_synth {
   set resp.http.Cache-Control = "private, no-store, no-cache";
-  set resp.http.X-Cache = "SYNTH";
+  unset resp.http.Cache-Status;
+  unset resp.http.X-Cache;
+  unset resp.http.X-Pass-Reason;
   unset resp.http.Via;
   unset resp.http.X-Varnish;
   unset resp.http.Server;
   unset resp.http.Content-Disposition;
 }
 
-# ===== PURGE HANDLER =====
 sub vcl_purge {
   return (synth(200, "Purged"));
 }
\ No newline at end of file