feat(gui): TTL-desync toggle in client settings

Adds a TTL Desync toggle to the obfuscation section of the desktop client
settings, wired the same way as the Junk/TCP-fragmentation toggles: persisted in
client settings, applied into transport.ttl_desync in the built config, included
in the hot-reload fingerprint so flipping it while connected re-applies, and
labelled in both EN and RU. ttl_desync_auto is passed true, so the engine
measures the hop distance and aims the decoys itself — the user just flips it on.

ostp-gui/src/i18n.js

@@ -28,6 +28,8 @@ const translations = {
     label_kill_switch: 'Kill Switch',
     kill_switch_hint: 'Block non-VPN traffic when tunnel drops',
     label_transport: 'Transport Protocol',
+    label_ttl_desync: 'TTL Desync',
+    hint_ttl_desync: 'Decoy packets that die before the server (UDP, auto-tuned)',
     label_mtu: 'MTU Size',
     label_transport: 'Transport Protocol',
     label_sni: 'Stealth SNI (Fake Host)',
@@ -93,6 +95,8 @@ const translations = {
     label_kill_switch: 'Kill Switch',
     kill_switch_hint: 'Блокировать трафик вне VPN при обрыве связи',
     label_transport: 'Транспортный протокол',
+    label_ttl_desync: 'TTL-десинхронизация',
+    hint_ttl_desync: 'Пакеты-приманки, умирающие до сервера (UDP, авто-настройка)',
     label_mtu: 'Размер MTU',
     label_transport: 'Транспортный протокол',
     label_sni: 'Маскировочный SNI',

ostp-gui/src/index.html

@@ -336,6 +336,17 @@
             </div>
           </div>
 
+          <div class="toggle-row" style="border-top:none;">
+            <div class="toggle-text">
+              <span class="toggle-name" data-i18n="label_ttl_desync">TTL Desync</span>
+              <span class="toggle-hint" data-i18n="hint_ttl_desync">Decoy packets that die before the server (UDP, auto-tuned)</span>
+            </div>
+            <label class="toggle">
+              <input type="checkbox" id="cs-ttl-desync" />
+              <span class="toggle-track"><span class="toggle-thumb"></span></span>
+            </label>
+          </div>
+
         </div> <!-- client-settings-card -->
         
         <div class="app-version" id="app-version">OSTP GUI</div>

ostp-gui/src/main.js

@@ -161,6 +161,7 @@ const btnJunkDone     = $('btn-junk-done');
 
 const inTcpFrag       = $('cs-tcp-frag');
 const btnFragSettings = $('btn-frag-settings');
+const inTtlDesync     = $('cs-ttl-desync');
 const fragModal       = $('frag-modal');
 const inFragChunk     = $('cs-frag-chunk');
 const inFragSleep     = $('cs-frag-sleep');
@@ -318,7 +319,9 @@ function buildConfig() {
       frag_chunk: s.tcpFrag ? (s.fragChunk || 2) : (active.frag_chunk || 2),
       frag_sleep: s.tcpFrag ? (!isNaN(parseInt(s.fragSleep)) ? s.fragSleep : 2) : (active.frag_sleep !== undefined ? active.frag_sleep : 2),
       junk_pc: s.junkEnabled ? [s.junkPcMin || 2, s.junkPcMax || 5] : (active.junk_pc || [2, 5]),
-      junk_ps: s.junkEnabled ? [s.junkPsMin || 100, s.junkPsMax || 1000] : (active.junk_ps || [100, 1000])
+      junk_ps: s.junkEnabled ? [s.junkPsMin || 100, s.junkPsMax || 1000] : (active.junk_ps || [100, 1000]),
+      ttl_desync: !!s.ttlDesync,
+      ttl_desync_auto: true
     },
     tun: {
       enable: !!s.tun,
@@ -657,6 +660,7 @@ function loadSettingsIntoForm() {
   inTcpFrag.checked     = !!s.tcpFrag;
   inFragChunk.value     = s.fragChunk || 2;
   inFragSleep.value     = !isNaN(parseInt(s.fragSleep)) ? s.fragSleep : 2;
+  if (inTtlDesync) inTtlDesync.checked = !!s.ttlDesync;
   updateClientVisibility();
 }
 
@@ -692,6 +696,7 @@ function collectAndSaveSettings() {
     tcpFrag:      inTcpFrag.checked,
     fragChunk:    parseInt(inFragChunk.value) || 2,
     fragSleep:    !isNaN(parseInt(inFragSleep.value)) ? parseInt(inFragSleep.value) : 2,
+    ttlDesync:    inTtlDesync ? inTtlDesync.checked : false,
   };
   // Cheap and local: safe to run on every debounced keystroke.
   saveClientSettings(s);
@@ -715,7 +720,7 @@ function collectAndSaveSettings() {
     const tunnelRelevant = JSON.stringify([
       s.tun, s.killSwitch, s.mux, s.muxSessions, s.mtu, s.dns, s.socks,
       s.exDomains, s.exIps, s.exProcs, s.junkEnabled, s.junkPcMin, s.junkPcMax,
-      s.junkPsMin, s.junkPsMax, s.tcpFrag, s.fragChunk, s.fragSleep,
+      s.junkPsMin, s.junkPsMax, s.tcpFrag, s.fragChunk, s.fragSleep, s.ttlDesync,
     ]);
     if (tunnelRelevant !== lastAppliedTunnelConfig) {
       clearTimeout(hotReloadTimer);
@@ -901,7 +906,8 @@ window.addEventListener('DOMContentLoaded', async () => {
   wintunModal.addEventListener('click', e => { if (e.target === wintunModal) wintunModal.classList.add('hidden'); });
 
   // Client settings — wire all inputs
-  [inTun, inKillSwitch, inMux, inAutoconnect, inLaunchStartup, inDebug, inShowRtt, inShowSpeed, inJunkEnabled, inTcpFrag]
+  [inTun, inKillSwitch, inMux, inAutoconnect, inLaunchStartup, inDebug, inShowRtt, inShowSpeed, inJunkEnabled, inTcpFrag, inTtlDesync]
+    .filter(Boolean)
     .forEach(el => el.addEventListener('change', collectAndSaveSettings));
   [inMuxSessions, inMtu, inDns, inSocks, inExDomains, inExIps, inExProcs, inJunkPcMin, inJunkPcMax, inJunkPsMin, inJunkPsMax, inFragChunk, inFragSleep]
     .forEach(el => {