diff --git a/android/app/build.gradle b/android/app/build.gradle
index efa09414..7204016e 100644
--- a/android/app/build.gradle
+++ b/android/app/build.gradle
@@ -7,8 +7,8 @@ android {
         applicationId "olcxja.miarven"
         minSdkVersion rootProject.ext.minSdkVersion
         targetSdkVersion rootProject.ext.targetSdkVersion
-        versionCode 5
-        versionName "0.1.4"
+        versionCode 6
+        versionName "0.2.0"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         aaptOptions {
              // Files and dirs to omit from the packaged assets dir, modified to accommodate modern web apps.
diff --git a/android/app/src/main/assets/public/blah/en-cat.json b/android/app/src/main/assets/public/blah/en-cat.json
index 01a784ae..d3ffa2ed 100644
--- a/android/app/src/main/assets/public/blah/en-cat.json
+++ b/android/app/src/main/assets/public/blah/en-cat.json
@@ -233,6 +233,7 @@
     "message.reaction.removed": "Purreaction remeowed",
     "no.invite": "No meowvite",
     "not.a.member": "Not a meowmber",
+    "removed.from.group": "You got hissed out of the clowder",
     "not.in.group": "Not in purroup",
     "reaction.not.found": "Purreaction not meownd",
     "rotation.not.required": "Purrotation not meowquired",
diff --git a/android/app/src/main/assets/public/blah/en-us.json b/android/app/src/main/assets/public/blah/en-us.json
index fa67cf49..fc6eaaf1 100644
--- a/android/app/src/main/assets/public/blah/en-us.json
+++ b/android/app/src/main/assets/public/blah/en-us.json
@@ -233,6 +233,7 @@
     "message.reaction.removed": "Reaction removed",
     "no.invite": "No invite",
     "not.a.member": "Not a member",
+    "removed.from.group": "You were removed from the group",
     "not.in.group": "Not in group",
     "reaction.not.found": "Reaction not found",
     "rotation.not.required": "Rotation not required",
diff --git a/android/app/src/main/assets/public/blah/pl-pl.json b/android/app/src/main/assets/public/blah/pl-pl.json
index 68bed510..d8af39cc 100644
--- a/android/app/src/main/assets/public/blah/pl-pl.json
+++ b/android/app/src/main/assets/public/blah/pl-pl.json
@@ -231,6 +231,7 @@
     "message.reaction.removed": "Reakcja usunięta",
     "no.invite": "Brak zaproszenia",
     "not.a.member": "Nie jesteś członkiem",
+    "removed.from.group": "Zostałeś usunięty z grupy",
     "not.in.group": "Nie jesteś w grupie",
     "reaction.not.found": "Nie znaleziono reakcji",
     "rotation.not.required": "Rotacja niewymagana",
diff --git a/android/app/src/main/assets/public/login/index.html b/android/app/src/main/assets/public/login/index.html
index 111fc1b6..9ef4bf68 100644
--- a/android/app/src/main/assets/public/login/index.html
+++ b/android/app/src/main/assets/public/login/index.html
@@ -285,7 +285,7 @@
     const registerHost = document.getElementById("reg-host");
     const registerUsername = document.getElementById("reg-username");
     const registerPassword = document.getElementById("reg-password");
-    const registerPasswordConfirm = document.getElementById("reg-password");
+    const registerPasswordConfirm = document.getElementById("reg-confirm");
     const loginHost = document.getElementById("login-host");
     const loginUsername = document.getElementById("login-username");
     const loginPassword = document.getElementById("login-password");
@@ -382,6 +382,13 @@
             var sharedkey = await calcHybridSharedKeyClient(dataarray[0], dataarray[1]);
             sharedpvkey = sharedkey[2];
             createId = dataarray[2];
+            //sól z init jest wymagana - hasło zawsze przez PBKDF2
+            if (!dataarray[3]) {
+                showBlahNotification("error:something.wrong");
+                authContainer.className = 'auth-container show-register';
+                return;
+            }
+            let regCredHash = await deriveCredentialKdf(registerPassword.value, dataarray[3]);
             const captchaimage = await fetch(`${url}/createaccount?step=register`, {
                 method: 'POST',
                 body: JSON.stringify({
@@ -389,7 +396,7 @@
                     ciphertextMlKem: sharedkey[1],
                     idKey: createId,
                     username: await encrypt(registerUsername.value, sharedpvkey),
-                    password: await encrypt(await hashSHA3_512(registerPassword.value), sharedpvkey)
+                    password: await encrypt(regCredHash, sharedpvkey)
                 })
             });
             const clone = captchaimage.clone();
diff --git a/android/app/src/main/assets/public/main.js b/android/app/src/main/assets/public/main.js
index ff092762..fa231a06 100644
--- a/android/app/src/main/assets/public/main.js
+++ b/android/app/src/main/assets/public/main.js
@@ -83,7 +83,9 @@ async function packetEncPass(pass, key, accountId) {
 async function getNonce(accountId, key) {
 
     let nonce;
-    let fetchRes = await (await fetch(`${url}/nextnonce?id=${accountId}`)).text();
+    let fetchRes = await (await fetch(`${url}/nextnonce?id=${accountId}`, {
+        headers: {"X-Crypto": "g1"}
+    })).text();
 
     try {
         nonce = await decryptString(fetchRes, key);
@@ -123,7 +125,8 @@ async function calcHybridSharedKeyClient(pubX25519ServerBase64, pubMlKemServerBa
 
 function keyDataFromServerJson(jsonFromServer) {
     const data = JSON.parse(jsonFromServer);
-    return [data.pubX25519, data.pubMlKem, data.idKey]
+    //0=pubX25519, 1=pubMlKem, 2=idKey, 3=kdfSalt (wymagany do PBKDF2 przy rejestracji)
+    return [data.pubX25519, data.pubMlKem, data.idKey, data.kdfSalt]
 }
 
 function base64ToUint8(base64) {
@@ -705,25 +708,20 @@ async function decryptBytes(combinedBytes, passphrase) {
 
 async function encryptString(plainText, passphrase) {
     const encoder = new TextEncoder();
-    const data = encoder.encode(plainText);
     const pwHash = await crypto.subtle.digest('SHA-256', encoder.encode(passphrase));
 
     const key = await crypto.subtle.importKey(
-        'raw', pwHash, {name: 'AES-CBC'}, false, ['encrypt']
+        'raw', pwHash, {name: 'AES-GCM'}, false, ['encrypt']
     );
 
-    const iv = crypto.getRandomValues(new Uint8Array(16));
-    const encrypted = await crypto.subtle.encrypt(
-        {name: 'AES-CBC', iv: iv},
+    const iv = crypto.getRandomValues(new Uint8Array(12));
+    const encrypted = new Uint8Array(await crypto.subtle.encrypt(
+        {name: 'AES-GCM', iv: iv},
         key,
-        data
-    );
+        encoder.encode(plainText)
+    ));
 
-    const combined = new Uint8Array(iv.length + encrypted.byteLength);
-    combined.set(iv);
-    combined.set(new Uint8Array(encrypted), iv.length);
-
-    return uint8ToBase64(combined);
+    return "G1:" + uint8ToBase64(concatUint8(iv, encrypted));
 }
 
 async function encryptBytesWithNonce(dataUint8, key, nonce) {
@@ -732,37 +730,44 @@ async function encryptBytesWithNonce(dataUint8, key, nonce) {
     const pwHash = await crypto.subtle.digest('SHA-256', encoder.encode(passphrase));
 
     const importedKey = await crypto.subtle.importKey(
-        'raw', pwHash, {name: 'AES-CBC'}, false, ['encrypt']
+        'raw', pwHash, {name: 'AES-GCM'}, false, ['encrypt']
     );
 
-    const iv = crypto.getRandomValues(new Uint8Array(16));
-    const encrypted = await crypto.subtle.encrypt(
-        {name: 'AES-CBC', iv: iv},
+    const iv = crypto.getRandomValues(new Uint8Array(12));
+    const encrypted = new Uint8Array(await crypto.subtle.encrypt(
+        {name: 'AES-GCM', iv: iv},
         importedKey,
         dataUint8
-    );
+    ));
 
-    const combined = new Uint8Array(iv.length + encrypted.byteLength);
-    combined.set(iv);
-    combined.set(new Uint8Array(encrypted), iv.length);
+    const prefix = encoder.encode("G1:");
+    const combined = new Uint8Array(prefix.length + iv.length + encrypted.byteLength);
+    combined.set(prefix, 0);
+    combined.set(iv, prefix.length);
+    combined.set(encrypted, prefix.length + iv.length);
 
     return combined;
 }
 
 async function decryptString(base64Text, passphrase) {
+    //tylko AES-GCM ("G1:") - pakiety bez prefiksu odrzucane
+    if (typeof base64Text !== "string" || !base64Text.startsWith("G1:")) {
+        throw new Error("error:invalid.cipher.format");
+    }
+
     const encoder = new TextEncoder();
-    const combined = new Uint8Array(atob(base64Text).split("").map(c => c.charCodeAt(0)));
+    const combined = base64ToUint8(base64Text.substring(3));
 
     const pwHash = await crypto.subtle.digest('SHA-256', encoder.encode(passphrase));
     const key = await crypto.subtle.importKey(
-        'raw', pwHash, {name: 'AES-CBC'}, false, ['decrypt']
+        'raw', pwHash, {name: 'AES-GCM'}, false, ['decrypt']
     );
 
-    const iv = combined.slice(0, 16);
-    const data = combined.slice(16);
+    const iv = combined.slice(0, 12);
+    const data = combined.slice(12);
 
     const decrypted = await crypto.subtle.decrypt(
-        {name: 'AES-CBC', iv: iv},
+        {name: 'AES-GCM', iv: iv},
         key,
         data
     );
@@ -784,6 +789,7 @@ async function fetchPost(url, value) {
             method: "POST",
             body: value,
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, await getNonce(id, passwordHash))
             }
         });
@@ -806,6 +812,7 @@ async function fetchPostEnc(url, value) {
             method: "POST",
             body: await encryptWithNonce(value, passwordHash, nonce),
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, nonce)
             }
         });
@@ -835,6 +842,7 @@ async function fetchAsyncWAuth(url) {
         let response = await fetch(url, {
             method: "GET",
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, await getNonce(id, passwordHash))
             }
         });
@@ -864,17 +872,30 @@ async function Auth(loginUsername, loginPassword) {
         }
         let actualId = resolvedId.split(":")[0];
 
-        let passwordHash = await hashSHA3_512(loginPassword);
+        //sól KDF jest wymagana - konta bez soli nie mogą się zalogować
+        let saltRes = await fetchAsync(`${url}/kdfsalt?id=${actualId}`);
+        if (!saltRes || !saltRes.startsWith("P:")) {
+            return "error:invalid.username.or.password";
+        }
+        let credHash = await deriveCredentialKdf(loginPassword, saltRes.substring(2).trim());
+
         let response = await fetch(`${url}/auth?id=${actualId}`, {
             method: "GET",
             headers: {
-                "secret": await encryptWithNonce(passwordHash, passwordHash, await getNonce(actualId, passwordHash))
+                "X-Crypto": "g1",
+                "secret": await encryptWithNonce(credHash, credHash, await getNonce(actualId, credHash))
             }
         });
 
         let data = await response.text();
         if (data.startsWith("success:")) {
             data += "|" + actualId;
+            //utrwal globale sesyjne - dalsze żądania w tej sesji mają od razu ważny hash
+            passwordHash = credHash;
+            if (!id) {
+                id = actualId;
+                try { localStorage.setItem("id", actualId); } catch (e) {}
+            }
         }
         return data;
     } finally {
@@ -902,6 +923,7 @@ async function fetchEncrypted(request, body = "") {
 
                 , passwordHash, nonce),
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, nonce)
             }
         });
@@ -929,6 +951,7 @@ async function fetchEncryptedUpload(target, fileBytesUint8) {
             method: "POST",
             body: await encryptBytesWithNonce(fileBytesUint8, passwordHash, nonce),
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, nonce),
                 "target": await encryptWithNonce(target, passwordHash, nonce)
             }
@@ -1046,13 +1069,35 @@ function clearAction(actionid) {
 }
 
 
-async function hashSHA3_512(input) {
+//solony, wolny KDF - 600k iteracji PBKDF2-SHA256, wyjscie 512 bitow (128 hex)
+async function deriveCredentialKdf(passwordPlain, saltB64) {
     const encoder = new TextEncoder();
-    const data = encoder.encode(input);
-    const hashBuffer = await crypto.subtle.digest('SHA-512', data); //-3 kiedys xddddddddddddddddd
-    const hashArray = Array.from(new Uint8Array(hashBuffer));
-    const hashHex = hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
-    return hashHex;
+    const keyMaterial = await crypto.subtle.importKey(
+        "raw",
+        encoder.encode(passwordPlain),
+        {name: "PBKDF2"},
+        false,
+        ["deriveBits"]
+    );
+    const bits = await crypto.subtle.deriveBits(
+        {name: "PBKDF2", hash: "SHA-256", salt: base64ToUint8(saltB64), iterations: 600000},
+        keyMaterial,
+        512
+    );
+    return Array.from(new Uint8Array(bits)).map(b => b.toString(16).padStart(2, '0')).join('');
+}
+
+//zwraca null gdy brak konta/soli - celowo NIE rzuca, żeby nie wywalać bootu aplikacji
+//(strona logowania i świeży użytkownik nie mają soli; start() sam zrobi Auth i przekieruje)
+async function resolveCredentialHash(accountId) {
+    if (!accountId) return null;
+    try {
+        let res = await fetchAsync(`${url}/kdfsalt?id=${accountId}`);
+        if (res && res.startsWith("P:") && password) {
+            return await deriveCredentialKdf(password, res.substring(2).trim());
+        }
+    } catch (e) {}
+    return null;
 }
 
 //placeholder pfp
@@ -1402,9 +1447,10 @@ async function mainJS() {
     }
     
     await initBlahs();
-    await loadEmotes();
-
-    passwordHash = await hashSHA3_512(password);
+    //emotes.json leży w katalogu głównym - na stronie /login fetch by trafił w HTML
+    if (!window.location.pathname.includes("/login")) {
+        await loadEmotes();
+    }
 
     if (host) {
         await updateProtocolAndUrl(host);
@@ -1420,6 +1466,12 @@ async function mainJS() {
         }
     }
 
+    //hash tylko dla istniejącej sesji; brak soli/konta nie może blokować startu -
+    //start() i tak wykonuje własny Auth i przekieruje niezalogowanych na login
+    if (id && password) {
+        try { passwordHash = await resolveCredentialHash(id); } catch (e) { passwordHash = null; }
+    }
+
     await start();
 }
 
@@ -1873,6 +1925,7 @@ async function openProfile(accountId) {
     
     try {
         if (!accountId) accountId = window.id; //var fallback
+        accountId = sanitizeId(accountId);
         
         if (accountId.endsWith(';' + host)) {
             accountId = accountId.substring(0, accountId.length - host.length - 1);
@@ -1896,7 +1949,7 @@ async function openProfile(accountId) {
         let bio = await fetchAsync(`${url}/user/storage/public/getentry?id=${accountId}&e=larp.profile.bio`);
         if (bio.startsWith("error:")) bio = "";
         
-        let bioHtml = bio && bio.trim() !== "" ? `<div class="profile-bio">${bio.replace(/</g, "&lt;").replace(/>/g, "&gt;")}</div>` : "";
+        let bioHtml = bio && bio.trim() !== "" ? `<div class="profile-bio">${escapeHtml(bio)}</div>` : "";
         
         let isOwnProfile = accountId === id;
         let actionBtnHtml = "";
@@ -1992,8 +2045,8 @@ async function openProfile(accountId) {
             </div>
             <div class="profile-info">
                 <div>
-                    <div class="profile-name">${profileName}</div>
-                    <div class="profile-id-host">${profileName}:${profileHost} (${accountId.split(':')[0].split(';')[0]})</div>
+                    <div class="profile-name">${escapeHtml(profileName)}</div>
+                    <div class="profile-id-host">${escapeHtml(profileName)}:${escapeHtml(profileHost)} (${escapeHtml(accountId.split(':')[0].split(';')[0])})</div>
                     ${roleHtml}
                 </div>
                 ${bioHtml}
@@ -2129,7 +2182,7 @@ async function renderInvites(res, type) {
 
 
             if (invite.type === "dm") {
-                let id = invite.id;
+                let id = sanitizeId(invite.id);
 
                 if (!id.includes(":")) {
                     id += `:${host}`;
@@ -2144,7 +2197,7 @@ async function renderInvites(res, type) {
                 let actions = "";
                 let desc = "";
 
-                let displayName = username || onlyId;
+                let displayName = escapeHtml(username || onlyId);
                 if (type === "received") {
                     desc = `:desc.invite.dm.received:${displayName};${onlyId}`;
                     actions = `
@@ -2174,8 +2227,8 @@ async function renderInvites(res, type) {
 
                 html += entry;
             } else if (invite.type === "group") {
-                let groupId = invite.groupId || invite.id;
-                let targetId = (type === "received") ? invite.sender : invite.receiver;
+                let groupId = sanitizeId(invite.groupId || invite.id);
+                let targetId = sanitizeId((type === "received") ? invite.sender : invite.receiver);
 
                 if (!targetId.includes(":")) {
                     targetId += `:${host}`;
@@ -2198,9 +2251,9 @@ async function renderInvites(res, type) {
                 let actions = "";
                 let desc = "";
 
-                let displayName = username || onlyId;
-                let val1 = `<span onclick="openProfile('${targetId}')" style="cursor:pointer"><b>${displayName}</b></span>`;
-                let val2 = `<span onclick="openProfile('${targetId}')" style="cursor:pointer"><b>${onlyId}</b></span>`;
+                let displayName = escapeHtml(username || onlyId);
+                let val1 = `<span onclick="openProfile('${sanitizeId(targetId)}')" style="cursor:pointer"><b>${displayName}</b></span>`;
+                let val2 = `<span onclick="openProfile('${sanitizeId(targetId)}')" style="cursor:pointer"><b>${escapeHtml(onlyId)}</b></span>`;
 
                 if (type === "received") {
                     desc = `:desc.invite.group.received:${val1};${val2}`;
@@ -2606,16 +2659,17 @@ async function renderDms(res) {
         let html = "";
         let count = 0;
 
-        for (let [dmId, dmData] of dmEntries) {
+        for (let [dmIdRaw, dmData] of dmEntries) {
+            let dmId = sanitizeId(dmIdRaw);
             let parts = dmId.split('_');
             let myId = `${id};${host}`;
-            let targetId = parts[0] === myId ? parts[1] : parts[0];
+            let targetId = sanitizeId(parts[0] === myId ? parts[1] : parts[0]);
 
             let targetUsername = await fetchAsync(`${url}/idtoname?id=${targetId}`);
             if (!targetUsername || targetUsername.trim() === "" || targetUsername.startsWith("error:")) continue;
 
             let pfp = await getAvatarUrl(targetId, targetUsername);
-            let displayName = targetUsername.split(':')[0];
+            let displayName = escapeHtml(targetUsername.split(':')[0]);
 
             let isRead = dmData.string3 === "true";
             let nameStyle = isRead ? "opacity: 0.8;" : "opacity: 1;";
@@ -2629,7 +2683,7 @@ async function renderDms(res) {
                 <img src="${pfp}" class="room-pfp">
                 <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
                     <span class="room-name" style="${nameStyle}">${displayName}</span>
-                    <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${targetUsername} (${targetId.split(';')[0]})</span>
+                    <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtml(targetUsername)} (${escapeHtml(targetId.split(';')[0])})</span>
                 </div>
                 ${unreadBadge}
             </button>
@@ -2685,19 +2739,23 @@ async function renderGroups(res) {
                 let safeGroupName = encodeURIComponent(groupName).replace(/'/g, "%27");
                 let pfp = await getGroupAvatarUrl(groupId, groupName);
 
+                let safeGroupId = sanitizeId(groupId);
                 let unreadBadge = `<div class="unread-badge ${isRead ? "" : "show"}"></div>`;
 
                 html += `
-                <button class="room-entry" id="group-btn-${groupId}" onclick="openDm('${groupId}', decodeURIComponent('${safeGroupName}'), '${groupId}', 'groups')" oncontextmenu="handleGroupContextMenu(event, '${groupId}')">
+                <button class="room-entry" id="group-btn-${safeGroupId}" onclick="openDm('${safeGroupId}', decodeURIComponent('${safeGroupName}'), '${safeGroupId}', 'groups')" oncontextmenu="handleGroupContextMenu(event, '${safeGroupId}')">
                     <img src="${pfp}" class="room-pfp">
                     <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
-                        <span class="room-name" style="${nameStyle}">${groupName}</span>
-                        <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${groupId.replace(';', ':')}</span>
+                        <span class="room-name" style="${nameStyle}">${escapeHtmlText(groupName)}</span>
+                        <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtmlText(groupId.replace(';', ':'))}</span>
                     </div>
                     ${unreadBadge}
                 </button>
                 `;
                 count++;
+            } else if (infoRes === "error:group.not.found") {
+                //grupa została usunięta - wyczyść nieaktualny wpis z listy
+                removeRoomFromCachedList(groupId, 'groups');
             }
         }
 
@@ -2743,6 +2801,18 @@ function escapeHtml(unsafe) {
         .replaceAll(/'/g, "&#039;");
 }
 
+//ID-y/identyfikatory wstawiane do atrybutów HTML i inline JS (onclick).
+//Usuwa wszystko poza bezpiecznym zestawem znakow - nie da się wyjść z stringa JS ani atrybutu.
+//Dozwolone: litery, cyfry oraz _ . ; : @ -
+function sanitizeId(value) {
+    return String(value ?? "").replace(/[^A-Za-z0-9_.;:@-]/g, "");
+}
+
+//nazwy (grup itp.) wstawiane do treści HTML
+function escapeHtmlText(value) {
+    return escapeHtml(String(value ?? ""));
+}
+
 async function generateDmMembersHtml(targetId, targetUsername) {
     let myIdStr = id + ";" + host;
     let myUsername = await fetchAsync(`${url}/idtoname?id=${myIdStr}`);
@@ -2751,24 +2821,28 @@ async function generateDmMembersHtml(targetId, targetUsername) {
     let targetPfp = await getAvatarUrl(targetId, targetUsername);
     let targetDisplayName = targetUsername.split(':')[0];
     let myDisplayName = myUsername.split(':')[0];
+    let safeTargetId = sanitizeId(targetId);
+    let safeMyId = sanitizeId(myIdStr);
+    targetDisplayName = escapeHtmlText(targetDisplayName);
+    let myDisplaySafe = escapeHtmlText(myDisplayName);
 
     return `
     <div class="list-container no-flex-grow" style="padding: 0 0.5rem; width: 100%;">
         <div class="sidebar-section-header" style="margin-top: 0.5rem; margin-bottom: 0.5rem; width: 100%;">
             <span style="padding-left: 0.6rem; font-size: 0.8rem; font-weight: bold; opacity: 0.5; text-transform: uppercase;"><blah>title.members</blah></span>
         </div>
-        <button class="room-entry" onclick="openProfile('${targetId}')" style="margin-bottom: 0;">
+        <button class="room-entry" onclick="openProfile('${safeTargetId}')" style="margin-bottom: 0;">
             <img src="${targetPfp}" class="room-pfp">
             <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
                 <span class="room-name">${targetDisplayName}</span>
-                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${targetUsername}</span>
+                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtmlText(targetUsername)}</span>
             </div>
         </button>
-        <button class="room-entry" onclick="openProfile('${myIdStr}')" style="margin-bottom: 0;">
+        <button class="room-entry" onclick="openProfile('${safeMyId}')" style="margin-bottom: 0;">
             <img src="${myPfp}" class="room-pfp">
             <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
-                <span class="room-name">${myDisplayName}</span>
-                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${myUsername}</span>
+                <span class="room-name">${myDisplaySafe}</span>
+                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtmlText(myUsername)}</span>
             </div>
         </button>
     </div>
@@ -2885,7 +2959,7 @@ async function generateGroupMembersHtml(groupId, groupName) {
         <div class="sidebar-section-header" style="margin-top: 0.5rem; margin-bottom: 0.5rem; width: 100%; display: flex; align-items: center;">
             <span style="padding-left: 0.6rem; font-size: 0.8rem; font-weight: bold; opacity: 0.5; text-transform: uppercase;"><blah>title.members</blah></span>
             <div class="flex-spacer"></div>
-            <button class="topbar-action-btn" onclick="inviteToGroupPrompt('${groupId}')" style="margin-right: 0.5rem; width: 1.2rem; height: 1.2rem; display: flex; align-items: center; justify-content: center; opacity: 0.7;">
+            <button class="topbar-action-btn" onclick="inviteToGroupPrompt('${sanitizeId(groupId)}')" style="margin-right: 0.5rem; width: 1.2rem; height: 1.2rem; display: flex; align-items: center; justify-content: center; opacity: 0.7;">
                 ${ICONS.plus({ width: "1rem", height: "1rem" })}
             </button>
         </div>`;
@@ -2895,14 +2969,16 @@ async function generateGroupMembersHtml(groupId, groupName) {
         if (!memberUsername || memberUsername.startsWith("error")) continue;
         
         let memberPfp = await getAvatarUrl(memberId, memberUsername);
-        let memberDisplayName = memberUsername.split(':')[0];
+        let memberDisplayName = escapeHtml(memberUsername.split(':')[0]);
+        let safeMemberId = sanitizeId(memberId);
+        let safeGroupId = sanitizeId(groupId);
         
         html += `
-        <button class="room-entry" onclick="openProfile('${memberId}')" oncontextmenu="handleMemberContextMenu(event, '${groupId}', '${memberId}')" style="margin-bottom: 0;">
+        <button class="room-entry" onclick="openProfile('${safeMemberId}')" oncontextmenu="handleMemberContextMenu(event, '${safeGroupId}', '${safeMemberId}')" style="margin-bottom: 0;">
             <img src="${memberPfp}" class="room-pfp">
             <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
                 <span class="room-name">${memberDisplayName}</span>
-                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${memberUsername}</span>
+                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtml(memberUsername)}</span>
             </div>
         </button>`;
     }
@@ -2925,6 +3001,16 @@ async function openDm(dmId, username, targetId, type = 'dms') {
         }
 
         if (type === 'dms') {
+            let keyCheck = await fetchEncrypted("dm/key/get", dmId);
+            if (keyCheck === "error:forbidden") {
+                //wpis w liscie do ktorego nie mamy dostepu - usun go i nie otwieraj rozmowy
+                showBlahNotification(keyCheck);
+                removeRoomFromCachedList(dmId, 'dms');
+                removeRoomButton(sanitizeId(dmId), 'dms');
+                refreshDms(0, false);
+                clearAction("dmopen");
+                return;
+            }
             currentDmKey = await ensureDmRoomKey(dmId);
             if (!currentDmKey) {
                 throw new Error("Missing DM room key");
@@ -2936,8 +3022,16 @@ async function openDm(dmId, username, targetId, type = 'dms') {
                 window.currentGroupKeyIndex = info.string4 || "0";
                 window.currentGroupOwner = info.string7;
             } else {
-                window.currentGroupKeyIndex = "0";
-                window.currentGroupOwner = "";
+                showBlahNotification(infoPayload && infoPayload.startsWith("error:") ? infoPayload : "error:group.not.found");
+                //usuń wpis z listy tylko przy deterministycznym błędzie
+                //(network.error itp. nie może czyścić poprawnych wpisów)
+                if (infoPayload === "error:group.not.found") {
+                    removeRoomFromCachedList(dmId, 'groups');
+                    removeRoomButton(sanitizeId(dmId), 'groups');
+                    refreshGroups(0, false);
+                }
+                clearAction("dmopen");
+                return;
             }
         }
         
@@ -3015,13 +3109,9 @@ async function loadDmMessages(dmId, startOffset = "", isPrepend = false) {
 
         if (res && res.startsWith("error:")) {
             if (res === "error:forbidden" || res === "error:not.a.member" || res === "error:group.not.found") {
-                if (dmMessagePollInterval) clearInterval(dmMessagePollInterval);
-                currentDmId = null;
-                showBlahNotification(res);
-                if (mainScreen.classList.contains('mobile-details')) {
-                    mainScreen.classList.remove('mobile-details');
-                }
-                switchDetailsContent("title.details", `<div style="text-align: center; opacity: 0.5; padding: 1rem; margin-top: 2rem;"><blah>desc.no.chat.selected</blah></div>`);
+                //brak dostępu do pokoju - serwer usunął też nieaktualny wpis z listy,
+                //my dodatkowo czyścimy cache/UI i wychodzimy z ekranu rozmowy
+                await handleLostRoomAccess(dmId, null, res);
                 return;
             }
             showBlahNotification(res);
@@ -3143,7 +3233,8 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                                 }
                             }
 
-                            let attContainerId = `att-container-${msgId}-${att.id}`;
+                            let safeAttId = sanitizeId(att.id);
+                            let attContainerId = `att-container-${sanitizeId(String(msgId))}-${safeAttId}`;
                             let isMedia = att.type && (att.type.startsWith("image/") || att.type.startsWith("video/"));
                             let sizeStr = att.size ? formatBytes(att.size) : "";
                             let displayName = truncateFilename(att.name, 25);
@@ -3154,7 +3245,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                             let safeType = encodeURIComponent(att.type).replace(/'/g, "%27");
                             let safeName = encodeURIComponent(att.name).replace(/'/g, "%27");
 
-                            attachmentsHtml += `<div id="${attContainerId}" class="attachment-box" style="position: relative; min-width: 7.5rem; max-width: 18.75rem; min-height: 6.25rem; max-height: 18.75rem; background: rgba(0,0,0,0.2); border: 0.0625rem solid var(--border-color); border-radius: 0.5rem; display: flex; align-items: center; justify-content: center; cursor: pointer; overflow: hidden;" onclick="event.stopPropagation(); downloadAndRenderAttachment(this, '${msgId}', '${att.id}', decodeURIComponent('${safeType}'), decodeURIComponent('${safeName}'), '${msg.key || "0"}')">
+                            attachmentsHtml += `<div id="${attContainerId}" class="attachment-box" style="position: relative; min-width: 7.5rem; max-width: 18.75rem; min-height: 6.25rem; max-height: 18.75rem; background: rgba(0,0,0,0.2); border: 0.0625rem solid var(--border-color); border-radius: 0.5rem; display: flex; align-items: center; justify-content: center; cursor: pointer; overflow: hidden;" onclick="event.stopPropagation(); downloadAndRenderAttachment(this, '${sanitizeId(String(msgId))}', '${safeAttId}', decodeURIComponent('${safeType}'), decodeURIComponent('${safeName}'), '${sanitizeId(msg.key) || "0"}')">
                                 <div style="padding: 1rem; text-align: center; color: var(--text-color);">
                                     ${iconSvg}
                                     <div style="font-size: 0.8rem; margin-top: 0.5rem; word-break: break-all;">${escapeHtml(displayName)}</div>
@@ -3215,11 +3306,11 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                 else if (msg.type === "larp.info.pfp") actionStr = "group.pfp.changed.by";
                 else if (msg.type === "larp.info.pfp_removed") actionStr = "group.pfp.removed.by";
                 
-                let clickableAuthor = `<span onclick="event.stopPropagation(); openProfile('${msg.author}')" style="cursor: pointer; font-weight: bold;">${authorName}</span>`;
+                let clickableAuthor = `<span onclick="event.stopPropagation(); openProfile('${sanitizeId(msg.author)}')" style="cursor: pointer; font-weight: bold;">${authorName}</span>`;
                 
                 let textStr = processBlah(actionStr);
                 if (msg.type.endsWith(".pin") || msg.type.endsWith(".unpin")) {
-                    let clickableMsg = `<span onclick="event.stopPropagation(); scrollToPinnedMessage(event, '${msg.pervious}')" style="cursor: pointer; font-weight: bold; color: rgba(255, 255, 255, 0.9);">${processBlah('title.message.lowercase')}</span>`;
+                    let clickableMsg = `<span onclick="event.stopPropagation(); scrollToPinnedMessage(event, '${sanitizeId(msg.pervious)}')" style="cursor: pointer; font-weight: bold; color: rgba(255, 255, 255, 0.9);">${processBlah('title.message.lowercase')}</span>`;
                     content = textStr.replace("{0}", clickableAuthor).replace("{1}", clickableMsg);
                 } else if (msg.type === "larp.info.history" || msg.type === "larp.info.name") {
                     let escapedContent = escapeHtml(content);
@@ -3229,7 +3320,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                     let targetId = "";
                     let parts = content.split(':');
                     if (parts.length >= 2 && parts[0].includes(';')) {
-                        targetId = parts[0];
+                        targetId = sanitizeId(parts[0]);
                         targetUsername = escapeHtml(parts.slice(1).join(':'));
                     } else {
                         targetUsername = escapeHtml(parts[0]);
@@ -3275,7 +3366,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                     dmPfpCache[msg.author] = await getAvatarUrl(msg.author, dmUsernameCache[msg.author]);
                 }
                 if (dmUsernameCache[msg.author]) {
-                    authorName = dmUsernameCache[msg.author].split(':')[0];
+                    authorName = escapeHtml(dmUsernameCache[msg.author].split(':')[0]);
                     pfp = dmPfpCache[msg.author];
                 }
             }
@@ -3355,7 +3446,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                                     window.replyAuthorCache[respondedId] = sName;
                                     let el = document.getElementById(randId);
                                     if (el) {
-                                        el.innerHTML = `${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${sName}`;
+                                        el.innerHTML = `${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${escapeHtml(sName)}`;
                                     }
                                 }
                             }
@@ -3365,7 +3456,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                 }
 
                 let divIdStr = randId !== "" ? `id="${randId}" ` : "";
-                repliedHtml = `<div ${divIdStr}class="chat-message-replied" style="font-size: 0.8rem; opacity: 0.7; margin-bottom: 0.2rem; cursor: pointer;" onclick="event.stopPropagation(); scrollToMessage('${respondedId}')">${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${replyAuthor}</div>`;
+                repliedHtml = `<div ${divIdStr}class="chat-message-replied" style="font-size: 0.8rem; opacity: 0.7; margin-bottom: 0.2rem; cursor: pointer;" onclick="event.stopPropagation(); scrollToMessage('${sanitizeId(respondedId)}')">${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${escapeHtml(replyAuthor)}</div>`;
             }
 
             let reactionsHtml = "";
@@ -3405,7 +3496,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                                 let safeRx = encodeURIComponent(rxVal).replace(/'/g, "%27");
                                 let escapedRxVal = escapeHtml(rxVal);
                                 let pillStyle = `display: inline-flex; align-items: center; gap: 0.35rem; padding: 0.1rem 0.45rem; border-radius: 1rem; font-size: 0.85rem; border: var(--border-width) solid var(--light-border-color); cursor: pointer; ${style}`;
-                                reactionsHtml += `<span class="reaction-pill" style="${pillStyle}" onclick="event.stopPropagation(); reactMessagePrompt('${msgId}', '${safeRx}')"><span>${processBlah(escapedRxVal)}</span>${rxCounts[rxVal].count > 1 ? `<span style="opacity: 0.5;">${rxCounts[rxVal].count}</span>` : ""}</span>`;
+                                reactionsHtml += `<span class="reaction-pill" style="${pillStyle}" onclick="event.stopPropagation(); reactMessagePrompt('${sanitizeId(String(msgId))}', '${safeRx}')"><span>${processBlah(escapedRxVal)}</span>${rxCounts[rxVal].count > 1 ? `<span style="opacity: 0.5;">${rxCounts[rxVal].count}</span>` : ""}</span>`;
                             }
                             reactionsHtml += `</div>`;
                         }
@@ -3415,11 +3506,11 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
             }
 
             html += `
-            <div class="chat-message ${extraClass}${isPinnedContext ? ` chat-message-pinned-item` : ``}" data-msg-id="${msgId}" id="${isPinnedContext ? `pinned-` : ``}msg-${msgId}"${isPinnedContext ? ` onclick="scrollToPinnedMessage(event, '${msgId}')"` : ``} style="${isPinnedContext ? `cursor: pointer;` : ``}">
-                ${showAvatar ? `<img src="${pfp}" class="chat-message-pfp" onclick="event.stopPropagation(); openProfile('${msg.author}')" style="cursor: pointer;">` : `<div style="width: 2.5rem; flex-shrink: 0;"></div>`}
-                <div class="chat-message-content" oncontextmenu="handleMessageContextMenu(arguments[0], '${msgId}')">
+            <div class="chat-message ${extraClass}${isPinnedContext ? ` chat-message-pinned-item` : ``}" data-msg-id="${sanitizeId(String(msgId))}" id="${isPinnedContext ? `pinned-` : ``}msg-${sanitizeId(String(msgId))}"${isPinnedContext ? ` onclick="scrollToPinnedMessage(event, '${sanitizeId(String(msgId))}')"` : ``} style="${isPinnedContext ? `cursor: pointer;` : ``}">
+                ${showAvatar ? `<img src="${pfp}" class="chat-message-pfp" onclick="event.stopPropagation(); openProfile('${sanitizeId(msg.author)}')" style="cursor: pointer;">` : `<div style="width: 2.5rem; flex-shrink: 0;"></div>`}
+                <div class="chat-message-content" oncontextmenu="handleMessageContextMenu(arguments[0], '${sanitizeId(String(msgId))}')">
                     ${showAvatar ? `<div class="chat-message-header">
-                        <span class="chat-message-author" onclick="event.stopPropagation(); openProfile('${msg.author}')" style="cursor: pointer;">${authorName}</span>
+                        <span class="chat-message-author" onclick="event.stopPropagation(); openProfile('${sanitizeId(msg.author)}')" style="cursor: pointer;">${authorName}</span>
                         <span class="chat-message-timestamp">${timeStr}</span>
                     </div>` : ""}
                     ${repliedHtml}
@@ -3498,7 +3589,21 @@ async function renderMessages(messages, isPrepend = false) {
             let newAttachments = newChild.querySelector('.chat-message-attachments');
             if (newAttachments) {
                 if (oldAttachments) {
-                    if (oldAttachments.getAttribute('data-raw') !== newAttachments.getAttribute('data-raw')) oldAttachments.innerHTML = newAttachments.innerHTML;
+                    if (oldAttachments.getAttribute('data-raw') !== newAttachments.getAttribute('data-raw')) {
+                        //keep already downloaded/rendered attachment boxes alive across the update,
+                        //and always sync data-raw - otherwise every poll would see a stale attribute
+                        //and re-render (unloading) the attachments forever
+                        let loadedBoxes = {};
+                        oldAttachments.querySelectorAll('.attachment-box[data-loaded="true"]').forEach(box => {
+                            loadedBoxes[box.id] = box;
+                        });
+                        oldAttachments.innerHTML = newAttachments.innerHTML;
+                        oldAttachments.setAttribute('data-raw', newAttachments.getAttribute('data-raw'));
+                        for (let boxId in loadedBoxes) {
+                            let freshBox = oldAttachments.querySelector(`#${boxId}`);
+                            if (freshBox) freshBox.replaceWith(loadedBoxes[boxId]);
+                        }
+                    }
                 } else {
                     let contentNode = existingChild.querySelector('.chat-message-content');
                     if (oldReactions) contentNode.insertBefore(newAttachments, oldReactions);
@@ -3756,7 +3861,7 @@ async function sendMessage(sendbutton = document.getElementById("chat-sendmessag
         <div class="chat-message" id="${pendingMsgId}" style="opacity: 0.5;">
             <div style="width: 2.5rem; flex-shrink: 0;"></div>
             <div class="chat-message-content">
-                <div class="chat-message-text">${content} <span style="font-size: 0.8rem; opacity: 0.7;">(${processBlah("info.sending.message")})</span></div>
+                <div class="chat-message-text">${escapeHtml(content)} <span style="font-size: 0.8rem; opacity: 0.7;">(${processBlah("info.sending.message")})</span></div>
             </div>
         </div>
         `;
@@ -3788,6 +3893,7 @@ async function sendMessage(sendbutton = document.getElementById("chat-sendmessag
                     res = await fetch(`${url}/dm/attachment/staging?id=${id}`, {
                         method: "POST",
                         headers: {
+                            "X-Crypto": "g1",
                             "secret": await encryptWithNonce(passwordHash, passwordHash, nonce)
                         },
                         body: encryptedFileBytes
@@ -3991,6 +4097,10 @@ function setupWebSocket() {
                 }, 300);
             }
         }
+        else if (data.startsWith("group_removed:")) {
+            let removedGroupId = data.substring("group_removed:".length);
+            handleGroupRemoved(removedGroupId);
+        }
         else if (data.startsWith("call_update:")) {
             if (typeof handleCallUpdate === "function") {
                 handleCallUpdate(data);
@@ -4043,7 +4153,7 @@ function handleMessageContextMenu(e, msgId) {
         if (pinContainer) {
             let isPinned = msg && msg.pinned === "true";
             pinContainer.innerHTML = `
-            <button onclick="togglePinMessage('${msgId}')">
+            <button onclick="togglePinMessage('${sanitizeId(String(msgId))}')">
                 ${ICONS.pin()}
                 <span class="blah">${isPinned ? processBlah("title.unpin.message") : processBlah("title.pin.message")}</span>
             </button>`;
@@ -4459,7 +4569,14 @@ async function changePassword() {
     if (!newPass) return;
     showAction("action.account.saving", "accountsave");
     
-    let newPassHash = await hashSHA3_512(newPass);
+    //sól KDF konta (wymagana; nie zmienia się przy zmianie hasła)
+    let saltRes = await fetchAsync(`${url}/kdfsalt?id=${window.id}`);
+    if (!saltRes || !saltRes.startsWith("P:")) {
+        clearAction("accountsave");
+        showBlahNotification("error:kdf.salt.missing");
+        return;
+    }
+    let newPassHash = await deriveCredentialKdf(newPass, saltRes.substring(2).trim());
     let newUserKeysEncrypted = await encryptJsonWithPassword(userKeysPrivate, newPass);
     
     let payload = JSON.stringify({
@@ -4970,6 +5087,91 @@ if (cropperContainer) {
     }).observe(cropperContainer);
 }
 
+//Usuwa pokój z cache listy (dms/groups). Zwraca true jeśli coś usunięto.
+function removeRoomFromCachedList(roomId, type) {
+    try {
+        roomId = String(roomId);
+        if (type === 'groups') {
+            if (!window.cachedGroups) return false;
+            let parsed = JSON.parse(window.cachedGroups);
+            let removed = false;
+            if (parsed.groups && parsed.groups[roomId]) {
+                delete parsed.groups[roomId];
+                removed = true;
+            }
+            //fallback: wpis może być zapisany z domena albo bez
+            if (!removed && parsed.groups && !roomId.includes(';')) {
+                for (let key in parsed.groups) {
+                    if (key.split(';')[0] === roomId) {
+                        delete parsed.groups[key];
+                        removed = true;
+                        break;
+                    }
+                }
+            }
+            if (removed) window.cachedGroups = JSON.stringify(parsed);
+            return removed;
+        } else {
+            if (!window.cachedDms) return false;
+            let parsed = JSON.parse(window.cachedDms);
+            if (parsed.dms && parsed.dms[roomId]) {
+                delete parsed.dms[roomId];
+                window.cachedDms = JSON.stringify(parsed);
+                return true;
+            }
+        }
+    } catch (e) {
+        console.error(e);
+    }
+    return false;
+}
+
+function removeRoomButton(roomId, type) {
+    let btn = document.getElementById(`${type === 'groups' ? 'group' : 'dm'}-btn-${sanitizeId(roomId)}`);
+    if (btn) btn.remove();
+}
+
+//Serwer informuje, że użytkownik został usunięty z grupy (kick) -
+//usuń grupę z listy, a jeśli jest otwarta, wyjdź z ekranu rozmowy.
+async function handleGroupRemoved(groupId) {
+    try {
+        removeRoomFromCachedList(groupId, 'groups');
+        removeRoomButton(sanitizeId(groupId), 'groups');
+        if (currentDmId === groupId || (currentDmId && currentDmId.split(';')[0] === groupId.split(';')[0] && window.currentRoomType === 'groups')) {
+            await handleLostRoomAccess(groupId, 'groups', "info:removed.from.group");
+        }
+        if (typeof refreshGroups === 'function') refreshGroups(0, false);
+    } catch (e) {
+        console.error(e);
+    }
+}
+
+//Pokój do którego straciliśmy dostęp: usuń go z listy i wyjdź z ekranu rozmowy.
+async function handleLostRoomAccess(roomId, type = null, notifyKey = null) {
+    if (!type) type = window.currentRoomType === 'groups' ? 'groups' : 'dms';
+    let wasOpen = currentDmId === roomId;
+
+    removeRoomFromCachedList(roomId, type);
+    removeRoomButton(sanitizeId(roomId), type);
+
+    if (typeof refreshDms === 'function') refreshDms(0, false);
+    if (typeof refreshGroups === 'function') refreshGroups(0, false);
+
+    if (wasOpen) {
+        showBlahNotification(notifyKey || (type === 'groups' ? "error:not.a.member" : "error:forbidden"));
+        if (dmMessagePollInterval) {
+            clearInterval(dmMessagePollInterval);
+            dmMessagePollInterval = null;
+        }
+        currentDmId = null;
+        window.currentRoomType = null;
+        if (mainScreen.classList.contains('mobile-details')) {
+            mainScreen.classList.remove('mobile-details');
+        }
+        gotoHome();
+    }
+}
+
 function updateDmListUI(roomId, isRead, type = 'dms', timestamp = null) {
     try {
         if (type === 'groups') {
@@ -5226,6 +5428,9 @@ function handleMemberContextMenu(e, groupId, memberId) {
     e.preventDefault();
     e.stopPropagation();
     
+    groupId = sanitizeId(groupId);
+    memberId = sanitizeId(memberId);
+    
     if (e && e.type === "contextmenu") {
         touchContextMenuFired = true;
         setTimeout(() => { touchContextMenuFired = false; }, 500);
diff --git a/android/app/src/main/assets/public/style.css b/android/app/src/main/assets/public/style.css
index 3247c504..6506b747 100644
--- a/android/app/src/main/assets/public/style.css
+++ b/android/app/src/main/assets/public/style.css
@@ -1418,10 +1418,16 @@ input:checked + .toggle-slider:before {
 .voice-resize-se { bottom: 0; right: 0; cursor: nwse-resize; }
 .voice-resize-sw { bottom: 0; left: 0; cursor: nesw-resize; }
 
+/*
+ * Kafelki rozmowy - wszystkie mają TEN SAM rozmiar (kwadrat, --voice-tile-size
+ * ustawiany przez relayoutVoiceTiles() w voice.js). Kafelki płyną obok siebie,
+ * a gdy się nie mieszczą w rzędzie, flex-wrap przenosi je do następnego.
+ */
 .voice-tile {
     position: relative;
-    width: var(--voice-tile-w, 9rem);
-    height: var(--voice-tile-h, 8rem);
+    width: var(--voice-tile-size, 9rem);
+    height: var(--voice-tile-size, 9rem);
+    flex: 0 0 auto;
     background: var(--light-border-color);
     background-size: cover;
     background-position: center;
@@ -1882,10 +1888,10 @@ input:checked + .toggle-slider:before {
     position: absolute;
     top: 0;
     bottom: 0;
-    width: 2px;
-    margin-left: -1px;
+    width: 0.125rem;
+    margin-left: -0.0625rem;
     background: rgba(255, 255, 255, 0.65);
-    border-radius: 1px;
+    border-radius: 0.0625rem;
     pointer-events: none;
 }
 /* Settings button keeps its hover look while the settings popup is open */
diff --git a/android/app/src/main/assets/public/version.js b/android/app/src/main/assets/public/version.js
index ca181587..98bb1f57 100644
--- a/android/app/src/main/assets/public/version.js
+++ b/android/app/src/main/assets/public/version.js
@@ -1 +1 @@
-const CLIENT_VERSION = "0.1.4";
+const CLIENT_VERSION = "0.2.0";
diff --git a/android/app/src/main/assets/public/voice.js b/android/app/src/main/assets/public/voice.js
index d4cf5d78..09dd8f0f 100644
--- a/android/app/src/main/assets/public/voice.js
+++ b/android/app/src/main/assets/public/voice.js
@@ -3,10 +3,99 @@ let currentVoiceCallId = null;
 let currentVoiceCallType = null;
 let voiceWsHeartbeat = null;
 let voiceActiveUsers = [];
-let voiceAesKeyBytes = null;
-let voiceAesCryptoKey = null;
+let voiceAesKeyBytes = null;      // grupowy klucz rozmowy (root) - dystrybuowany hybrydą PQ
 let voiceUiContainer = null;
 
+// === Gwarantowana unikalność IV (AES-GCM): ===
+// 1) każdy nadawca szyfruje WŁASNYM podkluczem HKDF(root, "larpix:voice:v1:"+senderId)
+//    -> kolizja między nadawcami niemożliwa z konstrukcji,
+// 2) IV(12B) = epoka(4B = SHA-256(ticketPublicId)[0..4]) || licznik(8B BE, ściśle rosnący)
+//    -> kolizja w ramach jednego nadawcy niemożliwa w obrębie epoki; każde dołączenie
+//    do calla ma unikalny ticketPublicId (single-use po stronie serwera), a licznik
+//    może się resetować TYLKO razem ze zmianą klucza root.
+let voiceMySenderCryptoKey = null;        // mój podklucz nadawcy (CryptoKey)
+const voicePeerSenderKeys = new Map();    // clientIdStr -> Promise<CryptoKey> odbiorczy
+let voiceSendEpoch = null;                // Uint8Array(4)
+let voiceSendCounter = 0n;                // BigInt, monotoniczny w ramach epoki
+
+//Promise rozstrzygany gdy operacja na kluczu root (ustawienie/wyczyszczenie)
+//jest gotowa - pozwala innym kodom czekać zamiast wchodzić w wyścig z derivacją.
+let voiceRootKeyReady = Promise.resolve();
+
+const VOICE_HKDF_INFO_PREFIX = "larpix:voice:v1:";
+
+function voiceHkdfInfoBytes(senderIdStr) {
+    const prefix = new TextEncoder().encode(VOICE_HKDF_INFO_PREFIX);
+    const idBytes = new TextEncoder().encode(String(senderIdStr));
+    const out = new Uint8Array(prefix.length + idBytes.length);
+    out.set(prefix, 0);
+    out.set(idBytes, prefix.length);
+    return out;
+}
+
+async function deriveVoiceSenderKey(rootBytes, senderIdStr) {
+    const ikm = await crypto.subtle.importKey("raw", rootBytes, "HKDF", false, ["deriveBits"]);
+    const bits = await crypto.subtle.deriveBits(
+        {name: "HKDF", hash: "SHA-256", salt: new Uint8Array(0), info: voiceHkdfInfoBytes(senderIdStr)},
+        ikm, 256
+    );
+    return await crypto.subtle.importKey("raw", new Uint8Array(bits), {name: "AES-GCM"}, false, ["encrypt", "decrypt"]);
+}
+
+//Jedyny punkt zmiany klucza root. Reset licznika jest poprawny wyłącznie tutaj -
+//nowy root = świeża przestrzeń IV. Null czyści cały stan.
+function setVoiceRootKey(bytesOrNull) {
+    const done = (async () => {
+        if (!bytesOrNull) {
+            voiceAesKeyBytes = null;
+            voiceMySenderCryptoKey = null;
+            voicePeerSenderKeys.clear();
+            return;
+        }
+        voicePeerSenderKeys.clear();
+        const k = await deriveVoiceSenderKey(bytesOrNull, String(window.id));
+        voiceAesKeyBytes = bytesOrNull;
+        voiceMySenderCryptoKey = k;
+    })();
+    voiceRootKeyReady = done;
+    return done;
+}
+
+//Epoka z unikalnego per-dołączenie ticketPublicId - deterministycznie, bez dodatkowego losowania.
+function setVoiceEpochFromTicket(publicIdB64u) {
+    crypto.subtle.digest("SHA-256", new TextEncoder().encode(String(publicIdB64u))).then(d => {
+        voiceSendEpoch = new Uint8Array(d).slice(0, 4);
+        voiceSendCounter = 0n;
+    }).catch(() => { voiceSendEpoch = null; voiceSendCounter = 0n; });
+}
+
+//Jedynne źródło IV do wysyłki. Inkrementacja synchroniczna (single-thread JS = atomiczne).
+function nextVoiceIv() {
+    if (!voiceSendEpoch) throw new Error("voice epoch not ready");
+    voiceSendCounter += 1n;
+    if (voiceSendCounter >= (1n << 63n)) throw new Error("voice iv counter exhausted"); //praktycznie nieosiągalne
+    const iv = new Uint8Array(12);
+    iv.set(voiceSendEpoch, 0);
+    let c = voiceSendCounter;
+    for (let i = 0; i < 8; i++) {
+        iv[11 - i] = Number(c & 0xffn);
+        c >>= 8n;
+    }
+    return iv;
+}
+
+//Podklucz odbiorczy danego nadawcy (cache). clientId to dziesiętny string ulonga - 
+//dokładnie ta sama forma, której nadawca użył przy derivacji własnego klucza.
+function getVoicePeerSenderKey(clientIdStr) {
+    let p = voicePeerSenderKeys.get(clientIdStr);
+    if (!p && voiceAesKeyBytes) {
+        p = deriveVoiceSenderKey(voiceAesKeyBytes, clientIdStr);
+        voicePeerSenderKeys.set(clientIdStr, p);
+    }
+    return p || null;
+}
+
+
 let micStream = null, audioContext = null, isAudioWorkletLoaded = false;
 let micSourceNode = null, senderNode = null, receiverNode = null, audioEncoder = null;
 let remoteAudio = {}, audioDecoders = {}, audioDecryptChains = {};
@@ -39,6 +128,8 @@ let peerLastSeen = {};
 let deadPeers = new Set();
 let lastVoiceServerPacketAt = 0;
 let voicePingTimer = null;
+let voiceRosterRetryTimer = null;
+let lastVoiceKeyRequestAt = 0;
 let voiceReconnectAttempts = 0;
 let voiceSocketOpenedAt = 0;
 
@@ -61,9 +152,9 @@ function cleanupPeerMedia(userId) {
 }
 
 function sendVoicePing() {
-    if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN || !voiceAesCryptoKey) return;
-    const iv = crypto.getRandomValues(new Uint8Array(12));
-    crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, new Uint8Array([Date.now() & 255])).then(cipher => {
+    if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN || !voiceMySenderCryptoKey) return;
+    const iv = nextVoiceIv();
+    crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, new Uint8Array([Date.now() & 255])).then(cipher => {
         if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN) return;
         const payload = new Uint8Array(14 + cipher.byteLength);
         payload[0] = 5; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
@@ -530,6 +621,16 @@ setInterval(() => {
         } else if (audioContext && audioContext.state === 'suspended') {
             audioContext.resume().catch(() => {});
         }
+        // Safety net for the call-key handshake: if others are in the call but
+        // we never received the root key (raced/lost signal), ask for it
+        // instead of staying deaf until someone refreshes the page.
+        if (others > 0 && !voiceAesKeyBytes && now - lastVoiceKeyRequestAt > 4000) {
+            lastVoiceKeyRequestAt = now;
+            console.debug("Voice: requesting call key from peers");
+            for (const u of voiceActiveUsers) {
+                if (u !== String(window.id)) sendVoiceSignalToUser(u, currentVoiceCallId, true);
+            }
+        }
     }
     if (changed) updateVoiceUIUsers();
 }, 2000);
@@ -682,6 +783,8 @@ async function requestVoiceJoin() {
 
     let serverUrl = parts[0];
     const [publicId, connKey, proof] = [parts[1], parts[2], parts[3]];
+    //epoka IV z unikalnego (single-use) publicId - każde dołączenie = rozłączna przestrzeń IV
+    setVoiceEpochFromTicket(publicId);
     if (!serverUrl.startsWith("ws://") && !serverUrl.startsWith("wss://")) {
         serverUrl = serverUrl.includes("localhost") || serverUrl.includes("127.0.0.1") ? "ws://" + serverUrl : "wss://" + serverUrl;
     }
@@ -780,7 +883,21 @@ async function startVoiceSession(serverUrl, ticket) {
                 } catch (e) {}
             };
             fetchUsers();
-            voiceWsHeartbeat = setInterval(fetchUsers, 5000);
+            //The voice-server roster is joined only AFTER ticket validation (an
+            //HTTP roundtrip to the main server), so the immediate fetch can still
+            //miss us - retry quickly until our own tile shows up instead of
+            //staring at an empty call for the first heartbeat.
+            if (voiceRosterRetryTimer) clearInterval(voiceRosterRetryTimer);
+            let rosterTries = 0;
+            voiceRosterRetryTimer = setInterval(() => {
+                if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN ||
+                    voiceActiveUsers.includes(String(window.id)) || ++rosterTries > 12) {
+                    clearInterval(voiceRosterRetryTimer);
+                    voiceRosterRetryTimer = null;
+                    return;
+                }
+                fetchUsers();
+            }, 400);
 
             voiceReconnectAttempts = 0;
             lastVoiceServerPacketAt = Date.now();
@@ -847,9 +964,9 @@ async function startVoiceSession(serverUrl, ticket) {
                     if (micLevelBar) micLevelBar.style.backgroundColor = 'var(--big-green)';
                     if (vdsLevelFill) vdsLevelFill.style.backgroundColor = 'var(--big-green)';
                     
-                    if (!voiceAesCryptoKey) return;
-                    const iv = crypto.getRandomValues(new Uint8Array(12));
-                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, audioData);
+                    if (!voiceMySenderCryptoKey) return;
+                    const iv = nextVoiceIv();
+                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, audioData);
                     const payload = new Uint8Array(14 + cipher.byteLength);
                     payload[0] = 0; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
                     currentVoiceWs.send(payload.buffer);
@@ -886,7 +1003,10 @@ async function startVoiceSession(serverUrl, ticket) {
             const iv = new Uint8Array(arrayBuffer, 10, 12);
             const ciphertext = new Uint8Array(arrayBuffer, 22);
             
-            if (!voiceAesCryptoKey) return; 
+            if (!voiceAesKeyBytes) return; 
+
+            //podklucz nadawcy - deterministyczny z (root, clientId)
+            const senderKeyPromise = getVoicePeerSenderKey(clientId);
             
             if (type === 0 || type === 4) {
                 const isScreenAudio = (type === 4);
@@ -899,7 +1019,9 @@ async function startVoiceSession(serverUrl, ticket) {
                 const targetReceiver = isScreenAudio ? screenReceiverNode : receiverNode;
                 audioDecryptChains[audioId].enqueue(async () => {
                     try {
-                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, ciphertext);
+                        const senderKey = await senderKeyPromise;
+                        if (!senderKey) return;
+                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, senderKey, ciphertext);
                         if(targetReceiver) targetReceiver.port.postMessage({ clientId: audioId, audioData: decryptedBuffer }, [decryptedBuffer]);
 
                         setTileSpeaking(clientId, true, isScreenAudio ? `${clientId}-2` : null);
@@ -911,7 +1033,9 @@ async function startVoiceSession(serverUrl, ticket) {
                 
                 videoDecryptChains[decoderId].enqueue(async () => {
                     try {
-                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, ciphertext);
+                        const senderKey = await senderKeyPromise;
+                        if (!senderKey) return;
+                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, senderKey, ciphertext);
                         
                         if (!remoteVideos[decoderId]) {
                             const canvas = document.createElement('canvas');
@@ -971,8 +1095,12 @@ async function startVoiceSession(serverUrl, ticket) {
                     } catch (err) {}
                 });
             } else if (type === 3) {
-                crypto.subtle.decrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, ciphertext).then(decrypted => {
-                    const stoppedTypeId = new Uint8Array(decrypted)[0];
+                (async () => {
+                    try {
+                        const senderKey = await senderKeyPromise;
+                        if (!senderKey) return;
+                        const decrypted = await crypto.subtle.decrypt({name: "AES-GCM", iv}, senderKey, ciphertext);
+                        const stoppedTypeId = new Uint8Array(decrypted)[0];
                     if (stoppedTypeId === 4) {
                         const audioId = `${clientId}_screen`;
                         if (remoteAudio[audioId]) {
@@ -989,7 +1117,8 @@ async function startVoiceSession(serverUrl, ticket) {
                             updateVoiceUIUsers();
                         }
                     }
-                 }).catch(() => {});
+                    } catch (err) {}
+                })();
             }
         };
         
@@ -1021,9 +1150,12 @@ async function startVoiceSession(serverUrl, ticket) {
     }
 }
 
-function handleCallUpdate(data) {
+async function handleCallUpdate(data) {
     let parts = data.split(":");
     let roomId = parts[1];
+    //Ignore updates for rooms we have nothing to do with - they would otherwise
+    //overwrite the participant list of an ongoing call and wipe its tiles.
+    if (roomId !== currentVoiceCallId && roomId !== window.currentDmId) return;
     let state = [];
     if(parts.slice(2).join(":") !== "") {
         let stateRaw = JSON.parse(parts.slice(2).join(":"));
@@ -1034,10 +1166,13 @@ function handleCallUpdate(data) {
     if (currentVoiceCallId === roomId) {
         let myIdStr = String(window.id);
         if (!voiceAesKeyBytes && state.length === 1 && state[0] === myIdStr) {
-            voiceAesKeyBytes = crypto.getRandomValues(new Uint8Array(32));
-            crypto.subtle.importKey("raw", voiceAesKeyBytes, {name: "AES-GCM"}, false, ["encrypt", "decrypt"])
-                .then(k => voiceAesCryptoKey = k);
+            setVoiceRootKey(crypto.getRandomValues(new Uint8Array(32)));
         }
+        //The root key is set asynchronously - wait for it before distributing.
+        //Otherwise a fast second join produces [me,peer] while the derivation
+        //is still running, no signal is sent and the peer never gets the key
+        //(audio stayed broken for everyone until someone refreshed the page).
+        await voiceRootKeyReady;
         if (voiceAesKeyBytes) {
             for (let u of state) {
                 if (u !== myIdStr) sendVoiceSignalToUser(u, roomId);
@@ -1120,7 +1255,7 @@ async function resolveCallerInfo(roomId) {
 }
 
 function showIncomingCallUI(roomId) {
-    if (document.getElementById("incoming-call-popup") || currentVoiceWs) return;
+    if (document.getElementById("incoming-call-popup") || currentVoiceWs || voiceJoinInFlight) return;
 
     let cachedName = window.dmUsernameCache ? window.dmUsernameCache[roomId] : null;
     if (cachedName && cachedName.includes(':')) cachedName = cachedName.split(':')[0];
@@ -1174,18 +1309,24 @@ function joinIncomingCall(roomId) {
     initiateVoiceCall(roomId);
 }
 
-async function sendVoiceSignalToUser(targetUserId, roomId) {
+async function sendVoiceSignalToUser(targetUserId, roomId, requestData = false) {
     try {
-        let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${targetUserId}`);
-        let publicKeys = JSON.parse(publicKeysRaw);
-        let hybrid = await deriveHybridKeyToUser(publicKeys);
-        
-        let encForMember = await encryptAesGcmToBase64(uint8ToBase64(voiceAesKeyBytes), hybrid.aesKeyBytes);
-        let setupPayloadJson = JSON.stringify({
-            v: 1,
-            ctMlKem: hybrid.ciphertextMlKemBase64,
-            enc: encForMember
-        });
+        let setupPayloadJson;
+        if (!requestData && voiceAesKeyBytes) {
+            let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${targetUserId}`);
+            let publicKeys = JSON.parse(publicKeysRaw);
+            let hybrid = await deriveHybridKeyToUser(publicKeys);
+
+            let encForMember = await encryptAesGcmToBase64(uint8ToBase64(voiceAesKeyBytes), hybrid.aesKeyBytes);
+            setupPayloadJson = JSON.stringify({
+                v: 1,
+                ctMlKem: hybrid.ciphertextMlKemBase64,
+                enc: encForMember
+            });
+        } else {
+            //Prośba o klucz rozmowy (bez sekretów) - adresat z kluczem odpowie pełnym sygnałem.
+            setupPayloadJson = JSON.stringify({ v: 1, needKey: true });
+        }
         
         let payload = JSON.stringify({
             string1: currentVoiceCallType,
@@ -1204,15 +1345,22 @@ async function handleRoomSignal(data) {
     let signalStr = parts.slice(2).join(":");
     let signalObj = JSON.parse(signalStr);
     
-    if (String(signalObj.to) === String(window.id) && roomId === currentVoiceCallId && !voiceAesKeyBytes) {
+    if (String(signalObj.to) === String(window.id) && roomId === currentVoiceCallId) {
         try {
             let setupData = JSON.parse(signalObj.data);
-            let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${signalObj.from}`); 
-            let otherPublicKeysObj = JSON.parse(publicKeysRaw);
-            let aesKeyBytes = await deriveHybridKeyFromSetup(otherPublicKeysObj, setupData.ctMlKem);
-            let decRoomKeyB64 = await decryptAesGcmFromBase64(setupData.enc, aesKeyBytes);
-            voiceAesKeyBytes = base64ToUint8(decRoomKeyB64);
-            voiceAesCryptoKey = await crypto.subtle.importKey("raw", voiceAesKeyBytes, {name: "AES-GCM"}, false, ["encrypt", "decrypt"]);
+            if (setupData.needKey) {
+                //Peer nie dostał klucza rozmowy (wygryziony/zagubiony sygnał) -
+                //odeślij mu go, ale tylko jeśli sami już go mamy.
+                if (voiceAesKeyBytes) await sendVoiceSignalToUser(signalObj.from, roomId);
+                return;
+            }
+            if (!voiceAesKeyBytes) {
+                let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${signalObj.from}`); 
+                let otherPublicKeysObj = JSON.parse(publicKeysRaw);
+                let aesKeyBytes = await deriveHybridKeyFromSetup(otherPublicKeysObj, setupData.ctMlKem);
+                let decRoomKeyB64 = await decryptAesGcmFromBase64(setupData.enc, aesKeyBytes);
+                await setVoiceRootKey(base64ToUint8(decRoomKeyB64));
+            }
         } catch(e) {
             console.error("Signal decryption failed", e);
         }
@@ -2038,6 +2186,12 @@ function ensureVoiceGridObserver() {
     voiceGridRO.observe(container);
 }
 
+/*
+ * Wszystkie kafelki to kwadraty o wspólnym rozmiarze --voice-tile-size.
+ * Wybieramy największy rozmiar kwadratu, przy którym n kafelków mieści się
+ * w oknie rozmowy - układanie i zawijanie do następnych rzędów robi sam
+ * flex-wrap w CSS (justify-content: center).
+ */
 function relayoutVoiceTiles() {
     let container = document.getElementById("voice-users");
     if (!container || !container.isConnected) return;
@@ -2052,28 +2206,34 @@ function relayoutVoiceTiles() {
     const innerH = container.clientHeight - parseFloat(cs.paddingTop) - parseFloat(cs.paddingBottom);
 
     if (!isFinite(innerW) || !isFinite(innerH) || !isFinite(rootFs) || innerW <= 0 || innerH <= 0 || rootFs <= 0) {
-        container.style.removeProperty("--voice-tile-w");
-        container.style.removeProperty("--voice-tile-h");
+        container.style.removeProperty("--voice-tile-size");
         delete container.dataset.layoutSig;
         return;
     }
 
-    const minCol = 6.25 * rootFs;
-    const minRow = 7 * rootFs;
     const gap = 0.75 * rootFs;
+    const maxSize = 18 * rootFs;   // jedna osoba nie dostanie gigantycznego kafelka
+    const minSize = 4.5 * rootFs;  // poniżej tego wolimy scrollować niż spłaszczać
 
-    const maxCols = Math.max(1, Math.floor((innerW + gap) / (minCol + gap)));
-    const cols = Math.min(n, maxCols);
-    const rows = Math.ceil(n / cols);
-    const w = Math.floor((innerW - gap * (cols - 1)) / cols);
-    const h = Math.floor(Math.max(minRow, (innerH - gap * (rows - 1)) / rows));
+    //Największy kwadrat, przy którym n kafelków mieści się w dostępnej powierzchni:
+    //próbujemy liczby kolumn 1..n, dla każdej wyliczamy ograniczony rozmiar
+    //(szerokość kolumny vs wysokość rzędu) i bierzemy najlepszy wariant.
+    let best = 0;
+    for (let cols = 1; cols <= n; cols++) {
+        const rows = Math.ceil(n / cols);
+        const s = Math.min(
+            (innerW - gap * (cols - 1)) / cols,
+            (innerH - gap * (rows - 1)) / rows
+        );
+        if (s > best) best = s;
+    }
 
-    const sig = `${n}:${cols}:${w}x${h}`;
+    const size = Math.min(maxSize, Math.max(minSize, Math.floor(best)));
+    const sig = `${n}:${size}`;
     if (container.dataset.layoutSig === sig) return;
     container.dataset.layoutSig = sig;
 
-    container.style.setProperty("--voice-tile-w", w + "px");
-    container.style.setProperty("--voice-tile-h", h + "px");
+    container.style.setProperty("--voice-tile-size", size + "px");
 }
 
 let voiceSettingsState = null;
@@ -2179,10 +2339,16 @@ function teardownVoiceTransport() {
     audioDecryptChains = {};
     peerLastSeen = {};
     deadPeers.clear();
+    if (voiceRosterRetryTimer) { clearInterval(voiceRosterRetryTimer); voiceRosterRetryTimer = null; }
+    lastVoiceKeyRequestAt = 0;
+    //Stale participants from the previous attempt must not linger in the UI
+    voiceActiveUsers = [];
+    updateVoiceUIUsers();
     if (receiverNode) receiverNode.port.postMessage({action: 'clear'});
     if (screenReceiverNode) screenReceiverNode.port.postMessage({action: 'clear'});
-    voiceAesKeyBytes = null;
-    voiceAesCryptoKey = null;
+    setVoiceRootKey(null);
+    voiceSendEpoch = null;
+    voiceSendCounter = 0n;
     lastVoiceServerPacketAt = Date.now();
 }
 
@@ -2243,8 +2409,11 @@ function endVoiceSession() {
     
     if (voiceWsHeartbeat) { clearInterval(voiceWsHeartbeat); voiceWsHeartbeat = null; }
     if (voicePingTimer) { clearInterval(voicePingTimer); voicePingTimer = null; }
+    if (voiceRosterRetryTimer) { clearInterval(voiceRosterRetryTimer); voiceRosterRetryTimer = null; }
     peerLastSeen = {};
     deadPeers.clear();
+    lastVoiceKeyRequestAt = 0;
+    voiceActiveUsers = [];
     
     for (let id in audioDecoders) {
         try { audioDecoders[id].close(); } catch(e){}
@@ -2275,8 +2444,9 @@ function endVoiceSession() {
     remoteVideos = {};
     videoDecryptChains = {};
     
-    voiceAesKeyBytes = null;
-    voiceAesCryptoKey = null;
+    setVoiceRootKey(null);
+    voiceSendEpoch = null;
+    voiceSendCounter = 0n;
     currentVoiceWs = null;
     currentVoiceCallType = null;
     currentVoiceCallId = null;
@@ -2322,11 +2492,11 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
                 screenAudioSourceNode = audioContext.createMediaStreamSource(stream);
                 screenSenderNode = new AudioWorkletNode(audioContext, 'audio-sender');
                 screenSenderNode.port.onmessage = async (e) => {
-                    if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceAesCryptoKey) return;
+                    if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceMySenderCryptoKey) return;
                     // Same backpressure valve as the mic sender.
                     if (currentVoiceWs.bufferedAmount > 256 * 1024) return;
-                    const iv = crypto.getRandomValues(new Uint8Array(12));
-                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, e.data.audioData);
+                    const iv = nextVoiceIv();
+                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, e.data.audioData);
                     const payload = new Uint8Array(14 + cipher.byteLength);
                     payload[0] = 4; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
                     currentVoiceWs.send(payload.buffer);
@@ -2357,10 +2527,10 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
         let currentConfig = getCurrentConfig(), isRunning = true, frameCount = 0;
         const encoder = new VideoEncoder({
             output: async (chunk) => {
-                if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceAesCryptoKey) return;
+                if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceMySenderCryptoKey) return;
                 const buffer = new ArrayBuffer(chunk.byteLength); chunk.copyTo(buffer);
-                const iv = crypto.getRandomValues(new Uint8Array(12));
-                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, buffer);
+                const iv = nextVoiceIv();
+                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, buffer);
                 const payload = new Uint8Array(14 + cipher.byteLength);
                 payload[0] = typeId; payload[1] = chunk.type === 'key' ? 1 : 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
                 currentVoiceWs.send(payload.buffer);
@@ -2412,9 +2582,9 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
             updateVoiceUIUsers();
             btnEl.classList.remove('voice-btn-active');
 
-            if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceAesCryptoKey) {
-                const buffer = new Uint8Array([typeId]); const iv = crypto.getRandomValues(new Uint8Array(12));
-                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, buffer);
+            if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceMySenderCryptoKey) {
+                const buffer = new Uint8Array([typeId]); const iv = nextVoiceIv();
+                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, buffer);
                 const payload = new Uint8Array(14 + cipher.byteLength);
                 payload[0] = 3; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14); currentVoiceWs.send(payload.buffer);
             }
@@ -2423,9 +2593,9 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
                 if (screenAudioSourceNode) { screenAudioSourceNode.disconnect(); screenAudioSourceNode = null; }
                 if (screenSenderNode) { screenSenderNode.disconnect(); screenSenderNode = null; }
                 if (screenAudioEncoder) { try { screenAudioEncoder.close(); } catch (e) {} screenAudioEncoder = null; }
-                if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceAesCryptoKey) {
-                    const bufferAudioInfo = new Uint8Array([4]); const ivA = crypto.getRandomValues(new Uint8Array(12));
-                    const cipherA = await crypto.subtle.encrypt({name: "AES-GCM", iv: ivA}, voiceAesCryptoKey, bufferAudioInfo);
+                if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceMySenderCryptoKey) {
+                    const bufferAudioInfo = new Uint8Array([4]); const ivA = nextVoiceIv();
+                    const cipherA = await crypto.subtle.encrypt({name: "AES-GCM", iv: ivA}, voiceMySenderCryptoKey, bufferAudioInfo);
                     const payloadA = new Uint8Array(14 + cipherA.byteLength);
                     payloadA[0] = 3; payloadA[1] = 0; payloadA.set(ivA, 2); payloadA.set(new Uint8Array(cipherA), 14); currentVoiceWs.send(payloadA.buffer);
                 }
diff --git a/electron/package.json b/electron/package.json
index 4b890f9c..5d883df0 100644
--- a/electron/package.json
+++ b/electron/package.json
@@ -1,6 +1,6 @@
 {
   "name": "Miarven",
-  "version": "0.1.4",
+  "version": "0.2.0",
   "description": "An Amazing Capacitor App",
   "author": {
     "name": "",
diff --git a/package.json b/package.json
index 404bb4c8..53c7193b 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "olcxja.miarven",
-  "version": "0.1.4",
+  "version": "0.2.0",
   "description": "Larpix client",
   "license": "AGPL-3.0",
   "author": "olcxja's softworks",
diff --git a/version.json b/version.json
index e6d29ba7..756f31ec 100644
--- a/version.json
+++ b/version.json
@@ -1,5 +1,5 @@
 {
-  "versionCode": 5,
-  "versionName": "0.1.4",
-  "npmVersion": "0.1.4"
+  "versionCode": 6,
+  "versionName": "0.2.0",
+  "npmVersion": "0.2.0"
 }
diff --git a/webroot/blah/en-cat.json b/webroot/blah/en-cat.json
index 01a784ae..d3ffa2ed 100644
--- a/webroot/blah/en-cat.json
+++ b/webroot/blah/en-cat.json
@@ -233,6 +233,7 @@
     "message.reaction.removed": "Purreaction remeowed",
     "no.invite": "No meowvite",
     "not.a.member": "Not a meowmber",
+    "removed.from.group": "You got hissed out of the clowder",
     "not.in.group": "Not in purroup",
     "reaction.not.found": "Purreaction not meownd",
     "rotation.not.required": "Purrotation not meowquired",
diff --git a/webroot/blah/en-us.json b/webroot/blah/en-us.json
index fa67cf49..fc6eaaf1 100644
--- a/webroot/blah/en-us.json
+++ b/webroot/blah/en-us.json
@@ -233,6 +233,7 @@
     "message.reaction.removed": "Reaction removed",
     "no.invite": "No invite",
     "not.a.member": "Not a member",
+    "removed.from.group": "You were removed from the group",
     "not.in.group": "Not in group",
     "reaction.not.found": "Reaction not found",
     "rotation.not.required": "Rotation not required",
diff --git a/webroot/blah/pl-pl.json b/webroot/blah/pl-pl.json
index 68bed510..d8af39cc 100644
--- a/webroot/blah/pl-pl.json
+++ b/webroot/blah/pl-pl.json
@@ -231,6 +231,7 @@
     "message.reaction.removed": "Reakcja usunięta",
     "no.invite": "Brak zaproszenia",
     "not.a.member": "Nie jesteś członkiem",
+    "removed.from.group": "Zostałeś usunięty z grupy",
     "not.in.group": "Nie jesteś w grupie",
     "reaction.not.found": "Nie znaleziono reakcji",
     "rotation.not.required": "Rotacja niewymagana",
diff --git a/webroot/login/index.html b/webroot/login/index.html
index 111fc1b6..9ef4bf68 100644
--- a/webroot/login/index.html
+++ b/webroot/login/index.html
@@ -285,7 +285,7 @@
     const registerHost = document.getElementById("reg-host");
     const registerUsername = document.getElementById("reg-username");
     const registerPassword = document.getElementById("reg-password");
-    const registerPasswordConfirm = document.getElementById("reg-password");
+    const registerPasswordConfirm = document.getElementById("reg-confirm");
     const loginHost = document.getElementById("login-host");
     const loginUsername = document.getElementById("login-username");
     const loginPassword = document.getElementById("login-password");
@@ -382,6 +382,13 @@
             var sharedkey = await calcHybridSharedKeyClient(dataarray[0], dataarray[1]);
             sharedpvkey = sharedkey[2];
             createId = dataarray[2];
+            //sól z init jest wymagana - hasło zawsze przez PBKDF2
+            if (!dataarray[3]) {
+                showBlahNotification("error:something.wrong");
+                authContainer.className = 'auth-container show-register';
+                return;
+            }
+            let regCredHash = await deriveCredentialKdf(registerPassword.value, dataarray[3]);
             const captchaimage = await fetch(`${url}/createaccount?step=register`, {
                 method: 'POST',
                 body: JSON.stringify({
@@ -389,7 +396,7 @@
                     ciphertextMlKem: sharedkey[1],
                     idKey: createId,
                     username: await encrypt(registerUsername.value, sharedpvkey),
-                    password: await encrypt(await hashSHA3_512(registerPassword.value), sharedpvkey)
+                    password: await encrypt(regCredHash, sharedpvkey)
                 })
             });
             const clone = captchaimage.clone();
diff --git a/webroot/main.js b/webroot/main.js
index ff092762..fa231a06 100644
--- a/webroot/main.js
+++ b/webroot/main.js
@@ -83,7 +83,9 @@ async function packetEncPass(pass, key, accountId) {
 async function getNonce(accountId, key) {
 
     let nonce;
-    let fetchRes = await (await fetch(`${url}/nextnonce?id=${accountId}`)).text();
+    let fetchRes = await (await fetch(`${url}/nextnonce?id=${accountId}`, {
+        headers: {"X-Crypto": "g1"}
+    })).text();
 
     try {
         nonce = await decryptString(fetchRes, key);
@@ -123,7 +125,8 @@ async function calcHybridSharedKeyClient(pubX25519ServerBase64, pubMlKemServerBa
 
 function keyDataFromServerJson(jsonFromServer) {
     const data = JSON.parse(jsonFromServer);
-    return [data.pubX25519, data.pubMlKem, data.idKey]
+    //0=pubX25519, 1=pubMlKem, 2=idKey, 3=kdfSalt (wymagany do PBKDF2 przy rejestracji)
+    return [data.pubX25519, data.pubMlKem, data.idKey, data.kdfSalt]
 }
 
 function base64ToUint8(base64) {
@@ -705,25 +708,20 @@ async function decryptBytes(combinedBytes, passphrase) {
 
 async function encryptString(plainText, passphrase) {
     const encoder = new TextEncoder();
-    const data = encoder.encode(plainText);
     const pwHash = await crypto.subtle.digest('SHA-256', encoder.encode(passphrase));
 
     const key = await crypto.subtle.importKey(
-        'raw', pwHash, {name: 'AES-CBC'}, false, ['encrypt']
+        'raw', pwHash, {name: 'AES-GCM'}, false, ['encrypt']
     );
 
-    const iv = crypto.getRandomValues(new Uint8Array(16));
-    const encrypted = await crypto.subtle.encrypt(
-        {name: 'AES-CBC', iv: iv},
+    const iv = crypto.getRandomValues(new Uint8Array(12));
+    const encrypted = new Uint8Array(await crypto.subtle.encrypt(
+        {name: 'AES-GCM', iv: iv},
         key,
-        data
-    );
+        encoder.encode(plainText)
+    ));
 
-    const combined = new Uint8Array(iv.length + encrypted.byteLength);
-    combined.set(iv);
-    combined.set(new Uint8Array(encrypted), iv.length);
-
-    return uint8ToBase64(combined);
+    return "G1:" + uint8ToBase64(concatUint8(iv, encrypted));
 }
 
 async function encryptBytesWithNonce(dataUint8, key, nonce) {
@@ -732,37 +730,44 @@ async function encryptBytesWithNonce(dataUint8, key, nonce) {
     const pwHash = await crypto.subtle.digest('SHA-256', encoder.encode(passphrase));
 
     const importedKey = await crypto.subtle.importKey(
-        'raw', pwHash, {name: 'AES-CBC'}, false, ['encrypt']
+        'raw', pwHash, {name: 'AES-GCM'}, false, ['encrypt']
     );
 
-    const iv = crypto.getRandomValues(new Uint8Array(16));
-    const encrypted = await crypto.subtle.encrypt(
-        {name: 'AES-CBC', iv: iv},
+    const iv = crypto.getRandomValues(new Uint8Array(12));
+    const encrypted = new Uint8Array(await crypto.subtle.encrypt(
+        {name: 'AES-GCM', iv: iv},
         importedKey,
         dataUint8
-    );
+    ));
 
-    const combined = new Uint8Array(iv.length + encrypted.byteLength);
-    combined.set(iv);
-    combined.set(new Uint8Array(encrypted), iv.length);
+    const prefix = encoder.encode("G1:");
+    const combined = new Uint8Array(prefix.length + iv.length + encrypted.byteLength);
+    combined.set(prefix, 0);
+    combined.set(iv, prefix.length);
+    combined.set(encrypted, prefix.length + iv.length);
 
     return combined;
 }
 
 async function decryptString(base64Text, passphrase) {
+    //tylko AES-GCM ("G1:") - pakiety bez prefiksu odrzucane
+    if (typeof base64Text !== "string" || !base64Text.startsWith("G1:")) {
+        throw new Error("error:invalid.cipher.format");
+    }
+
     const encoder = new TextEncoder();
-    const combined = new Uint8Array(atob(base64Text).split("").map(c => c.charCodeAt(0)));
+    const combined = base64ToUint8(base64Text.substring(3));
 
     const pwHash = await crypto.subtle.digest('SHA-256', encoder.encode(passphrase));
     const key = await crypto.subtle.importKey(
-        'raw', pwHash, {name: 'AES-CBC'}, false, ['decrypt']
+        'raw', pwHash, {name: 'AES-GCM'}, false, ['decrypt']
     );
 
-    const iv = combined.slice(0, 16);
-    const data = combined.slice(16);
+    const iv = combined.slice(0, 12);
+    const data = combined.slice(12);
 
     const decrypted = await crypto.subtle.decrypt(
-        {name: 'AES-CBC', iv: iv},
+        {name: 'AES-GCM', iv: iv},
         key,
         data
     );
@@ -784,6 +789,7 @@ async function fetchPost(url, value) {
             method: "POST",
             body: value,
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, await getNonce(id, passwordHash))
             }
         });
@@ -806,6 +812,7 @@ async function fetchPostEnc(url, value) {
             method: "POST",
             body: await encryptWithNonce(value, passwordHash, nonce),
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, nonce)
             }
         });
@@ -835,6 +842,7 @@ async function fetchAsyncWAuth(url) {
         let response = await fetch(url, {
             method: "GET",
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, await getNonce(id, passwordHash))
             }
         });
@@ -864,17 +872,30 @@ async function Auth(loginUsername, loginPassword) {
         }
         let actualId = resolvedId.split(":")[0];
 
-        let passwordHash = await hashSHA3_512(loginPassword);
+        //sól KDF jest wymagana - konta bez soli nie mogą się zalogować
+        let saltRes = await fetchAsync(`${url}/kdfsalt?id=${actualId}`);
+        if (!saltRes || !saltRes.startsWith("P:")) {
+            return "error:invalid.username.or.password";
+        }
+        let credHash = await deriveCredentialKdf(loginPassword, saltRes.substring(2).trim());
+
         let response = await fetch(`${url}/auth?id=${actualId}`, {
             method: "GET",
             headers: {
-                "secret": await encryptWithNonce(passwordHash, passwordHash, await getNonce(actualId, passwordHash))
+                "X-Crypto": "g1",
+                "secret": await encryptWithNonce(credHash, credHash, await getNonce(actualId, credHash))
             }
         });
 
         let data = await response.text();
         if (data.startsWith("success:")) {
             data += "|" + actualId;
+            //utrwal globale sesyjne - dalsze żądania w tej sesji mają od razu ważny hash
+            passwordHash = credHash;
+            if (!id) {
+                id = actualId;
+                try { localStorage.setItem("id", actualId); } catch (e) {}
+            }
         }
         return data;
     } finally {
@@ -902,6 +923,7 @@ async function fetchEncrypted(request, body = "") {
 
                 , passwordHash, nonce),
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, nonce)
             }
         });
@@ -929,6 +951,7 @@ async function fetchEncryptedUpload(target, fileBytesUint8) {
             method: "POST",
             body: await encryptBytesWithNonce(fileBytesUint8, passwordHash, nonce),
             headers: {
+                "X-Crypto": "g1",
                 "secret": await encryptWithNonce(passwordHash, passwordHash, nonce),
                 "target": await encryptWithNonce(target, passwordHash, nonce)
             }
@@ -1046,13 +1069,35 @@ function clearAction(actionid) {
 }
 
 
-async function hashSHA3_512(input) {
+//solony, wolny KDF - 600k iteracji PBKDF2-SHA256, wyjscie 512 bitow (128 hex)
+async function deriveCredentialKdf(passwordPlain, saltB64) {
     const encoder = new TextEncoder();
-    const data = encoder.encode(input);
-    const hashBuffer = await crypto.subtle.digest('SHA-512', data); //-3 kiedys xddddddddddddddddd
-    const hashArray = Array.from(new Uint8Array(hashBuffer));
-    const hashHex = hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
-    return hashHex;
+    const keyMaterial = await crypto.subtle.importKey(
+        "raw",
+        encoder.encode(passwordPlain),
+        {name: "PBKDF2"},
+        false,
+        ["deriveBits"]
+    );
+    const bits = await crypto.subtle.deriveBits(
+        {name: "PBKDF2", hash: "SHA-256", salt: base64ToUint8(saltB64), iterations: 600000},
+        keyMaterial,
+        512
+    );
+    return Array.from(new Uint8Array(bits)).map(b => b.toString(16).padStart(2, '0')).join('');
+}
+
+//zwraca null gdy brak konta/soli - celowo NIE rzuca, żeby nie wywalać bootu aplikacji
+//(strona logowania i świeży użytkownik nie mają soli; start() sam zrobi Auth i przekieruje)
+async function resolveCredentialHash(accountId) {
+    if (!accountId) return null;
+    try {
+        let res = await fetchAsync(`${url}/kdfsalt?id=${accountId}`);
+        if (res && res.startsWith("P:") && password) {
+            return await deriveCredentialKdf(password, res.substring(2).trim());
+        }
+    } catch (e) {}
+    return null;
 }
 
 //placeholder pfp
@@ -1402,9 +1447,10 @@ async function mainJS() {
     }
     
     await initBlahs();
-    await loadEmotes();
-
-    passwordHash = await hashSHA3_512(password);
+    //emotes.json leży w katalogu głównym - na stronie /login fetch by trafił w HTML
+    if (!window.location.pathname.includes("/login")) {
+        await loadEmotes();
+    }
 
     if (host) {
         await updateProtocolAndUrl(host);
@@ -1420,6 +1466,12 @@ async function mainJS() {
         }
     }
 
+    //hash tylko dla istniejącej sesji; brak soli/konta nie może blokować startu -
+    //start() i tak wykonuje własny Auth i przekieruje niezalogowanych na login
+    if (id && password) {
+        try { passwordHash = await resolveCredentialHash(id); } catch (e) { passwordHash = null; }
+    }
+
     await start();
 }
 
@@ -1873,6 +1925,7 @@ async function openProfile(accountId) {
     
     try {
         if (!accountId) accountId = window.id; //var fallback
+        accountId = sanitizeId(accountId);
         
         if (accountId.endsWith(';' + host)) {
             accountId = accountId.substring(0, accountId.length - host.length - 1);
@@ -1896,7 +1949,7 @@ async function openProfile(accountId) {
         let bio = await fetchAsync(`${url}/user/storage/public/getentry?id=${accountId}&e=larp.profile.bio`);
         if (bio.startsWith("error:")) bio = "";
         
-        let bioHtml = bio && bio.trim() !== "" ? `<div class="profile-bio">${bio.replace(/</g, "&lt;").replace(/>/g, "&gt;")}</div>` : "";
+        let bioHtml = bio && bio.trim() !== "" ? `<div class="profile-bio">${escapeHtml(bio)}</div>` : "";
         
         let isOwnProfile = accountId === id;
         let actionBtnHtml = "";
@@ -1992,8 +2045,8 @@ async function openProfile(accountId) {
             </div>
             <div class="profile-info">
                 <div>
-                    <div class="profile-name">${profileName}</div>
-                    <div class="profile-id-host">${profileName}:${profileHost} (${accountId.split(':')[0].split(';')[0]})</div>
+                    <div class="profile-name">${escapeHtml(profileName)}</div>
+                    <div class="profile-id-host">${escapeHtml(profileName)}:${escapeHtml(profileHost)} (${escapeHtml(accountId.split(':')[0].split(';')[0])})</div>
                     ${roleHtml}
                 </div>
                 ${bioHtml}
@@ -2129,7 +2182,7 @@ async function renderInvites(res, type) {
 
 
             if (invite.type === "dm") {
-                let id = invite.id;
+                let id = sanitizeId(invite.id);
 
                 if (!id.includes(":")) {
                     id += `:${host}`;
@@ -2144,7 +2197,7 @@ async function renderInvites(res, type) {
                 let actions = "";
                 let desc = "";
 
-                let displayName = username || onlyId;
+                let displayName = escapeHtml(username || onlyId);
                 if (type === "received") {
                     desc = `:desc.invite.dm.received:${displayName};${onlyId}`;
                     actions = `
@@ -2174,8 +2227,8 @@ async function renderInvites(res, type) {
 
                 html += entry;
             } else if (invite.type === "group") {
-                let groupId = invite.groupId || invite.id;
-                let targetId = (type === "received") ? invite.sender : invite.receiver;
+                let groupId = sanitizeId(invite.groupId || invite.id);
+                let targetId = sanitizeId((type === "received") ? invite.sender : invite.receiver);
 
                 if (!targetId.includes(":")) {
                     targetId += `:${host}`;
@@ -2198,9 +2251,9 @@ async function renderInvites(res, type) {
                 let actions = "";
                 let desc = "";
 
-                let displayName = username || onlyId;
-                let val1 = `<span onclick="openProfile('${targetId}')" style="cursor:pointer"><b>${displayName}</b></span>`;
-                let val2 = `<span onclick="openProfile('${targetId}')" style="cursor:pointer"><b>${onlyId}</b></span>`;
+                let displayName = escapeHtml(username || onlyId);
+                let val1 = `<span onclick="openProfile('${sanitizeId(targetId)}')" style="cursor:pointer"><b>${displayName}</b></span>`;
+                let val2 = `<span onclick="openProfile('${sanitizeId(targetId)}')" style="cursor:pointer"><b>${escapeHtml(onlyId)}</b></span>`;
 
                 if (type === "received") {
                     desc = `:desc.invite.group.received:${val1};${val2}`;
@@ -2606,16 +2659,17 @@ async function renderDms(res) {
         let html = "";
         let count = 0;
 
-        for (let [dmId, dmData] of dmEntries) {
+        for (let [dmIdRaw, dmData] of dmEntries) {
+            let dmId = sanitizeId(dmIdRaw);
             let parts = dmId.split('_');
             let myId = `${id};${host}`;
-            let targetId = parts[0] === myId ? parts[1] : parts[0];
+            let targetId = sanitizeId(parts[0] === myId ? parts[1] : parts[0]);
 
             let targetUsername = await fetchAsync(`${url}/idtoname?id=${targetId}`);
             if (!targetUsername || targetUsername.trim() === "" || targetUsername.startsWith("error:")) continue;
 
             let pfp = await getAvatarUrl(targetId, targetUsername);
-            let displayName = targetUsername.split(':')[0];
+            let displayName = escapeHtml(targetUsername.split(':')[0]);
 
             let isRead = dmData.string3 === "true";
             let nameStyle = isRead ? "opacity: 0.8;" : "opacity: 1;";
@@ -2629,7 +2683,7 @@ async function renderDms(res) {
                 <img src="${pfp}" class="room-pfp">
                 <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
                     <span class="room-name" style="${nameStyle}">${displayName}</span>
-                    <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${targetUsername} (${targetId.split(';')[0]})</span>
+                    <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtml(targetUsername)} (${escapeHtml(targetId.split(';')[0])})</span>
                 </div>
                 ${unreadBadge}
             </button>
@@ -2685,19 +2739,23 @@ async function renderGroups(res) {
                 let safeGroupName = encodeURIComponent(groupName).replace(/'/g, "%27");
                 let pfp = await getGroupAvatarUrl(groupId, groupName);
 
+                let safeGroupId = sanitizeId(groupId);
                 let unreadBadge = `<div class="unread-badge ${isRead ? "" : "show"}"></div>`;
 
                 html += `
-                <button class="room-entry" id="group-btn-${groupId}" onclick="openDm('${groupId}', decodeURIComponent('${safeGroupName}'), '${groupId}', 'groups')" oncontextmenu="handleGroupContextMenu(event, '${groupId}')">
+                <button class="room-entry" id="group-btn-${safeGroupId}" onclick="openDm('${safeGroupId}', decodeURIComponent('${safeGroupName}'), '${safeGroupId}', 'groups')" oncontextmenu="handleGroupContextMenu(event, '${safeGroupId}')">
                     <img src="${pfp}" class="room-pfp">
                     <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
-                        <span class="room-name" style="${nameStyle}">${groupName}</span>
-                        <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${groupId.replace(';', ':')}</span>
+                        <span class="room-name" style="${nameStyle}">${escapeHtmlText(groupName)}</span>
+                        <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtmlText(groupId.replace(';', ':'))}</span>
                     </div>
                     ${unreadBadge}
                 </button>
                 `;
                 count++;
+            } else if (infoRes === "error:group.not.found") {
+                //grupa została usunięta - wyczyść nieaktualny wpis z listy
+                removeRoomFromCachedList(groupId, 'groups');
             }
         }
 
@@ -2743,6 +2801,18 @@ function escapeHtml(unsafe) {
         .replaceAll(/'/g, "&#039;");
 }
 
+//ID-y/identyfikatory wstawiane do atrybutów HTML i inline JS (onclick).
+//Usuwa wszystko poza bezpiecznym zestawem znakow - nie da się wyjść z stringa JS ani atrybutu.
+//Dozwolone: litery, cyfry oraz _ . ; : @ -
+function sanitizeId(value) {
+    return String(value ?? "").replace(/[^A-Za-z0-9_.;:@-]/g, "");
+}
+
+//nazwy (grup itp.) wstawiane do treści HTML
+function escapeHtmlText(value) {
+    return escapeHtml(String(value ?? ""));
+}
+
 async function generateDmMembersHtml(targetId, targetUsername) {
     let myIdStr = id + ";" + host;
     let myUsername = await fetchAsync(`${url}/idtoname?id=${myIdStr}`);
@@ -2751,24 +2821,28 @@ async function generateDmMembersHtml(targetId, targetUsername) {
     let targetPfp = await getAvatarUrl(targetId, targetUsername);
     let targetDisplayName = targetUsername.split(':')[0];
     let myDisplayName = myUsername.split(':')[0];
+    let safeTargetId = sanitizeId(targetId);
+    let safeMyId = sanitizeId(myIdStr);
+    targetDisplayName = escapeHtmlText(targetDisplayName);
+    let myDisplaySafe = escapeHtmlText(myDisplayName);
 
     return `
     <div class="list-container no-flex-grow" style="padding: 0 0.5rem; width: 100%;">
         <div class="sidebar-section-header" style="margin-top: 0.5rem; margin-bottom: 0.5rem; width: 100%;">
             <span style="padding-left: 0.6rem; font-size: 0.8rem; font-weight: bold; opacity: 0.5; text-transform: uppercase;"><blah>title.members</blah></span>
         </div>
-        <button class="room-entry" onclick="openProfile('${targetId}')" style="margin-bottom: 0;">
+        <button class="room-entry" onclick="openProfile('${safeTargetId}')" style="margin-bottom: 0;">
             <img src="${targetPfp}" class="room-pfp">
             <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
                 <span class="room-name">${targetDisplayName}</span>
-                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${targetUsername}</span>
+                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtmlText(targetUsername)}</span>
             </div>
         </button>
-        <button class="room-entry" onclick="openProfile('${myIdStr}')" style="margin-bottom: 0;">
+        <button class="room-entry" onclick="openProfile('${safeMyId}')" style="margin-bottom: 0;">
             <img src="${myPfp}" class="room-pfp">
             <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
-                <span class="room-name">${myDisplayName}</span>
-                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${myUsername}</span>
+                <span class="room-name">${myDisplaySafe}</span>
+                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtmlText(myUsername)}</span>
             </div>
         </button>
     </div>
@@ -2885,7 +2959,7 @@ async function generateGroupMembersHtml(groupId, groupName) {
         <div class="sidebar-section-header" style="margin-top: 0.5rem; margin-bottom: 0.5rem; width: 100%; display: flex; align-items: center;">
             <span style="padding-left: 0.6rem; font-size: 0.8rem; font-weight: bold; opacity: 0.5; text-transform: uppercase;"><blah>title.members</blah></span>
             <div class="flex-spacer"></div>
-            <button class="topbar-action-btn" onclick="inviteToGroupPrompt('${groupId}')" style="margin-right: 0.5rem; width: 1.2rem; height: 1.2rem; display: flex; align-items: center; justify-content: center; opacity: 0.7;">
+            <button class="topbar-action-btn" onclick="inviteToGroupPrompt('${sanitizeId(groupId)}')" style="margin-right: 0.5rem; width: 1.2rem; height: 1.2rem; display: flex; align-items: center; justify-content: center; opacity: 0.7;">
                 ${ICONS.plus({ width: "1rem", height: "1rem" })}
             </button>
         </div>`;
@@ -2895,14 +2969,16 @@ async function generateGroupMembersHtml(groupId, groupName) {
         if (!memberUsername || memberUsername.startsWith("error")) continue;
         
         let memberPfp = await getAvatarUrl(memberId, memberUsername);
-        let memberDisplayName = memberUsername.split(':')[0];
+        let memberDisplayName = escapeHtml(memberUsername.split(':')[0]);
+        let safeMemberId = sanitizeId(memberId);
+        let safeGroupId = sanitizeId(groupId);
         
         html += `
-        <button class="room-entry" onclick="openProfile('${memberId}')" oncontextmenu="handleMemberContextMenu(event, '${groupId}', '${memberId}')" style="margin-bottom: 0;">
+        <button class="room-entry" onclick="openProfile('${safeMemberId}')" oncontextmenu="handleMemberContextMenu(event, '${safeGroupId}', '${safeMemberId}')" style="margin-bottom: 0;">
             <img src="${memberPfp}" class="room-pfp">
             <div style="display: flex; flex-direction: column; text-align: left; overflow: hidden; width: 100%; margin-left: 0.37rem;">
                 <span class="room-name">${memberDisplayName}</span>
-                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${memberUsername}</span>
+                <span class="room-id" style="font-size: 0.8rem; opacity: 0.6; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;">${escapeHtml(memberUsername)}</span>
             </div>
         </button>`;
     }
@@ -2925,6 +3001,16 @@ async function openDm(dmId, username, targetId, type = 'dms') {
         }
 
         if (type === 'dms') {
+            let keyCheck = await fetchEncrypted("dm/key/get", dmId);
+            if (keyCheck === "error:forbidden") {
+                //wpis w liscie do ktorego nie mamy dostepu - usun go i nie otwieraj rozmowy
+                showBlahNotification(keyCheck);
+                removeRoomFromCachedList(dmId, 'dms');
+                removeRoomButton(sanitizeId(dmId), 'dms');
+                refreshDms(0, false);
+                clearAction("dmopen");
+                return;
+            }
             currentDmKey = await ensureDmRoomKey(dmId);
             if (!currentDmKey) {
                 throw new Error("Missing DM room key");
@@ -2936,8 +3022,16 @@ async function openDm(dmId, username, targetId, type = 'dms') {
                 window.currentGroupKeyIndex = info.string4 || "0";
                 window.currentGroupOwner = info.string7;
             } else {
-                window.currentGroupKeyIndex = "0";
-                window.currentGroupOwner = "";
+                showBlahNotification(infoPayload && infoPayload.startsWith("error:") ? infoPayload : "error:group.not.found");
+                //usuń wpis z listy tylko przy deterministycznym błędzie
+                //(network.error itp. nie może czyścić poprawnych wpisów)
+                if (infoPayload === "error:group.not.found") {
+                    removeRoomFromCachedList(dmId, 'groups');
+                    removeRoomButton(sanitizeId(dmId), 'groups');
+                    refreshGroups(0, false);
+                }
+                clearAction("dmopen");
+                return;
             }
         }
         
@@ -3015,13 +3109,9 @@ async function loadDmMessages(dmId, startOffset = "", isPrepend = false) {
 
         if (res && res.startsWith("error:")) {
             if (res === "error:forbidden" || res === "error:not.a.member" || res === "error:group.not.found") {
-                if (dmMessagePollInterval) clearInterval(dmMessagePollInterval);
-                currentDmId = null;
-                showBlahNotification(res);
-                if (mainScreen.classList.contains('mobile-details')) {
-                    mainScreen.classList.remove('mobile-details');
-                }
-                switchDetailsContent("title.details", `<div style="text-align: center; opacity: 0.5; padding: 1rem; margin-top: 2rem;"><blah>desc.no.chat.selected</blah></div>`);
+                //brak dostępu do pokoju - serwer usunął też nieaktualny wpis z listy,
+                //my dodatkowo czyścimy cache/UI i wychodzimy z ekranu rozmowy
+                await handleLostRoomAccess(dmId, null, res);
                 return;
             }
             showBlahNotification(res);
@@ -3143,7 +3233,8 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                                 }
                             }
 
-                            let attContainerId = `att-container-${msgId}-${att.id}`;
+                            let safeAttId = sanitizeId(att.id);
+                            let attContainerId = `att-container-${sanitizeId(String(msgId))}-${safeAttId}`;
                             let isMedia = att.type && (att.type.startsWith("image/") || att.type.startsWith("video/"));
                             let sizeStr = att.size ? formatBytes(att.size) : "";
                             let displayName = truncateFilename(att.name, 25);
@@ -3154,7 +3245,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                             let safeType = encodeURIComponent(att.type).replace(/'/g, "%27");
                             let safeName = encodeURIComponent(att.name).replace(/'/g, "%27");
 
-                            attachmentsHtml += `<div id="${attContainerId}" class="attachment-box" style="position: relative; min-width: 7.5rem; max-width: 18.75rem; min-height: 6.25rem; max-height: 18.75rem; background: rgba(0,0,0,0.2); border: 0.0625rem solid var(--border-color); border-radius: 0.5rem; display: flex; align-items: center; justify-content: center; cursor: pointer; overflow: hidden;" onclick="event.stopPropagation(); downloadAndRenderAttachment(this, '${msgId}', '${att.id}', decodeURIComponent('${safeType}'), decodeURIComponent('${safeName}'), '${msg.key || "0"}')">
+                            attachmentsHtml += `<div id="${attContainerId}" class="attachment-box" style="position: relative; min-width: 7.5rem; max-width: 18.75rem; min-height: 6.25rem; max-height: 18.75rem; background: rgba(0,0,0,0.2); border: 0.0625rem solid var(--border-color); border-radius: 0.5rem; display: flex; align-items: center; justify-content: center; cursor: pointer; overflow: hidden;" onclick="event.stopPropagation(); downloadAndRenderAttachment(this, '${sanitizeId(String(msgId))}', '${safeAttId}', decodeURIComponent('${safeType}'), decodeURIComponent('${safeName}'), '${sanitizeId(msg.key) || "0"}')">
                                 <div style="padding: 1rem; text-align: center; color: var(--text-color);">
                                     ${iconSvg}
                                     <div style="font-size: 0.8rem; margin-top: 0.5rem; word-break: break-all;">${escapeHtml(displayName)}</div>
@@ -3215,11 +3306,11 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                 else if (msg.type === "larp.info.pfp") actionStr = "group.pfp.changed.by";
                 else if (msg.type === "larp.info.pfp_removed") actionStr = "group.pfp.removed.by";
                 
-                let clickableAuthor = `<span onclick="event.stopPropagation(); openProfile('${msg.author}')" style="cursor: pointer; font-weight: bold;">${authorName}</span>`;
+                let clickableAuthor = `<span onclick="event.stopPropagation(); openProfile('${sanitizeId(msg.author)}')" style="cursor: pointer; font-weight: bold;">${authorName}</span>`;
                 
                 let textStr = processBlah(actionStr);
                 if (msg.type.endsWith(".pin") || msg.type.endsWith(".unpin")) {
-                    let clickableMsg = `<span onclick="event.stopPropagation(); scrollToPinnedMessage(event, '${msg.pervious}')" style="cursor: pointer; font-weight: bold; color: rgba(255, 255, 255, 0.9);">${processBlah('title.message.lowercase')}</span>`;
+                    let clickableMsg = `<span onclick="event.stopPropagation(); scrollToPinnedMessage(event, '${sanitizeId(msg.pervious)}')" style="cursor: pointer; font-weight: bold; color: rgba(255, 255, 255, 0.9);">${processBlah('title.message.lowercase')}</span>`;
                     content = textStr.replace("{0}", clickableAuthor).replace("{1}", clickableMsg);
                 } else if (msg.type === "larp.info.history" || msg.type === "larp.info.name") {
                     let escapedContent = escapeHtml(content);
@@ -3229,7 +3320,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                     let targetId = "";
                     let parts = content.split(':');
                     if (parts.length >= 2 && parts[0].includes(';')) {
-                        targetId = parts[0];
+                        targetId = sanitizeId(parts[0]);
                         targetUsername = escapeHtml(parts.slice(1).join(':'));
                     } else {
                         targetUsername = escapeHtml(parts[0]);
@@ -3275,7 +3366,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                     dmPfpCache[msg.author] = await getAvatarUrl(msg.author, dmUsernameCache[msg.author]);
                 }
                 if (dmUsernameCache[msg.author]) {
-                    authorName = dmUsernameCache[msg.author].split(':')[0];
+                    authorName = escapeHtml(dmUsernameCache[msg.author].split(':')[0]);
                     pfp = dmPfpCache[msg.author];
                 }
             }
@@ -3355,7 +3446,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                                     window.replyAuthorCache[respondedId] = sName;
                                     let el = document.getElementById(randId);
                                     if (el) {
-                                        el.innerHTML = `${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${sName}`;
+                                        el.innerHTML = `${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${escapeHtml(sName)}`;
                                     }
                                 }
                             }
@@ -3365,7 +3456,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                 }
 
                 let divIdStr = randId !== "" ? `id="${randId}" ` : "";
-                repliedHtml = `<div ${divIdStr}class="chat-message-replied" style="font-size: 0.8rem; opacity: 0.7; margin-bottom: 0.2rem; cursor: pointer;" onclick="event.stopPropagation(); scrollToMessage('${respondedId}')">${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${replyAuthor}</div>`;
+                repliedHtml = `<div ${divIdStr}class="chat-message-replied" style="font-size: 0.8rem; opacity: 0.7; margin-bottom: 0.2rem; cursor: pointer;" onclick="event.stopPropagation(); scrollToMessage('${sanitizeId(respondedId)}')">${ICONS.cornerUpLeft({ width: "0.8rem", height: "0.8rem", stroke: "currentColor", style: "vertical-align: middle;" })} ${processBlah('title.replied.to')} ${escapeHtml(replyAuthor)}</div>`;
             }
 
             let reactionsHtml = "";
@@ -3405,7 +3496,7 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
                                 let safeRx = encodeURIComponent(rxVal).replace(/'/g, "%27");
                                 let escapedRxVal = escapeHtml(rxVal);
                                 let pillStyle = `display: inline-flex; align-items: center; gap: 0.35rem; padding: 0.1rem 0.45rem; border-radius: 1rem; font-size: 0.85rem; border: var(--border-width) solid var(--light-border-color); cursor: pointer; ${style}`;
-                                reactionsHtml += `<span class="reaction-pill" style="${pillStyle}" onclick="event.stopPropagation(); reactMessagePrompt('${msgId}', '${safeRx}')"><span>${processBlah(escapedRxVal)}</span>${rxCounts[rxVal].count > 1 ? `<span style="opacity: 0.5;">${rxCounts[rxVal].count}</span>` : ""}</span>`;
+                                reactionsHtml += `<span class="reaction-pill" style="${pillStyle}" onclick="event.stopPropagation(); reactMessagePrompt('${sanitizeId(String(msgId))}', '${safeRx}')"><span>${processBlah(escapedRxVal)}</span>${rxCounts[rxVal].count > 1 ? `<span style="opacity: 0.5;">${rxCounts[rxVal].count}</span>` : ""}</span>`;
                             }
                             reactionsHtml += `</div>`;
                         }
@@ -3415,11 +3506,11 @@ async function generateMessagesHtml(entries, isPinnedContext = false) {
             }
 
             html += `
-            <div class="chat-message ${extraClass}${isPinnedContext ? ` chat-message-pinned-item` : ``}" data-msg-id="${msgId}" id="${isPinnedContext ? `pinned-` : ``}msg-${msgId}"${isPinnedContext ? ` onclick="scrollToPinnedMessage(event, '${msgId}')"` : ``} style="${isPinnedContext ? `cursor: pointer;` : ``}">
-                ${showAvatar ? `<img src="${pfp}" class="chat-message-pfp" onclick="event.stopPropagation(); openProfile('${msg.author}')" style="cursor: pointer;">` : `<div style="width: 2.5rem; flex-shrink: 0;"></div>`}
-                <div class="chat-message-content" oncontextmenu="handleMessageContextMenu(arguments[0], '${msgId}')">
+            <div class="chat-message ${extraClass}${isPinnedContext ? ` chat-message-pinned-item` : ``}" data-msg-id="${sanitizeId(String(msgId))}" id="${isPinnedContext ? `pinned-` : ``}msg-${sanitizeId(String(msgId))}"${isPinnedContext ? ` onclick="scrollToPinnedMessage(event, '${sanitizeId(String(msgId))}')"` : ``} style="${isPinnedContext ? `cursor: pointer;` : ``}">
+                ${showAvatar ? `<img src="${pfp}" class="chat-message-pfp" onclick="event.stopPropagation(); openProfile('${sanitizeId(msg.author)}')" style="cursor: pointer;">` : `<div style="width: 2.5rem; flex-shrink: 0;"></div>`}
+                <div class="chat-message-content" oncontextmenu="handleMessageContextMenu(arguments[0], '${sanitizeId(String(msgId))}')">
                     ${showAvatar ? `<div class="chat-message-header">
-                        <span class="chat-message-author" onclick="event.stopPropagation(); openProfile('${msg.author}')" style="cursor: pointer;">${authorName}</span>
+                        <span class="chat-message-author" onclick="event.stopPropagation(); openProfile('${sanitizeId(msg.author)}')" style="cursor: pointer;">${authorName}</span>
                         <span class="chat-message-timestamp">${timeStr}</span>
                     </div>` : ""}
                     ${repliedHtml}
@@ -3498,7 +3589,21 @@ async function renderMessages(messages, isPrepend = false) {
             let newAttachments = newChild.querySelector('.chat-message-attachments');
             if (newAttachments) {
                 if (oldAttachments) {
-                    if (oldAttachments.getAttribute('data-raw') !== newAttachments.getAttribute('data-raw')) oldAttachments.innerHTML = newAttachments.innerHTML;
+                    if (oldAttachments.getAttribute('data-raw') !== newAttachments.getAttribute('data-raw')) {
+                        //keep already downloaded/rendered attachment boxes alive across the update,
+                        //and always sync data-raw - otherwise every poll would see a stale attribute
+                        //and re-render (unloading) the attachments forever
+                        let loadedBoxes = {};
+                        oldAttachments.querySelectorAll('.attachment-box[data-loaded="true"]').forEach(box => {
+                            loadedBoxes[box.id] = box;
+                        });
+                        oldAttachments.innerHTML = newAttachments.innerHTML;
+                        oldAttachments.setAttribute('data-raw', newAttachments.getAttribute('data-raw'));
+                        for (let boxId in loadedBoxes) {
+                            let freshBox = oldAttachments.querySelector(`#${boxId}`);
+                            if (freshBox) freshBox.replaceWith(loadedBoxes[boxId]);
+                        }
+                    }
                 } else {
                     let contentNode = existingChild.querySelector('.chat-message-content');
                     if (oldReactions) contentNode.insertBefore(newAttachments, oldReactions);
@@ -3756,7 +3861,7 @@ async function sendMessage(sendbutton = document.getElementById("chat-sendmessag
         <div class="chat-message" id="${pendingMsgId}" style="opacity: 0.5;">
             <div style="width: 2.5rem; flex-shrink: 0;"></div>
             <div class="chat-message-content">
-                <div class="chat-message-text">${content} <span style="font-size: 0.8rem; opacity: 0.7;">(${processBlah("info.sending.message")})</span></div>
+                <div class="chat-message-text">${escapeHtml(content)} <span style="font-size: 0.8rem; opacity: 0.7;">(${processBlah("info.sending.message")})</span></div>
             </div>
         </div>
         `;
@@ -3788,6 +3893,7 @@ async function sendMessage(sendbutton = document.getElementById("chat-sendmessag
                     res = await fetch(`${url}/dm/attachment/staging?id=${id}`, {
                         method: "POST",
                         headers: {
+                            "X-Crypto": "g1",
                             "secret": await encryptWithNonce(passwordHash, passwordHash, nonce)
                         },
                         body: encryptedFileBytes
@@ -3991,6 +4097,10 @@ function setupWebSocket() {
                 }, 300);
             }
         }
+        else if (data.startsWith("group_removed:")) {
+            let removedGroupId = data.substring("group_removed:".length);
+            handleGroupRemoved(removedGroupId);
+        }
         else if (data.startsWith("call_update:")) {
             if (typeof handleCallUpdate === "function") {
                 handleCallUpdate(data);
@@ -4043,7 +4153,7 @@ function handleMessageContextMenu(e, msgId) {
         if (pinContainer) {
             let isPinned = msg && msg.pinned === "true";
             pinContainer.innerHTML = `
-            <button onclick="togglePinMessage('${msgId}')">
+            <button onclick="togglePinMessage('${sanitizeId(String(msgId))}')">
                 ${ICONS.pin()}
                 <span class="blah">${isPinned ? processBlah("title.unpin.message") : processBlah("title.pin.message")}</span>
             </button>`;
@@ -4459,7 +4569,14 @@ async function changePassword() {
     if (!newPass) return;
     showAction("action.account.saving", "accountsave");
     
-    let newPassHash = await hashSHA3_512(newPass);
+    //sól KDF konta (wymagana; nie zmienia się przy zmianie hasła)
+    let saltRes = await fetchAsync(`${url}/kdfsalt?id=${window.id}`);
+    if (!saltRes || !saltRes.startsWith("P:")) {
+        clearAction("accountsave");
+        showBlahNotification("error:kdf.salt.missing");
+        return;
+    }
+    let newPassHash = await deriveCredentialKdf(newPass, saltRes.substring(2).trim());
     let newUserKeysEncrypted = await encryptJsonWithPassword(userKeysPrivate, newPass);
     
     let payload = JSON.stringify({
@@ -4970,6 +5087,91 @@ if (cropperContainer) {
     }).observe(cropperContainer);
 }
 
+//Usuwa pokój z cache listy (dms/groups). Zwraca true jeśli coś usunięto.
+function removeRoomFromCachedList(roomId, type) {
+    try {
+        roomId = String(roomId);
+        if (type === 'groups') {
+            if (!window.cachedGroups) return false;
+            let parsed = JSON.parse(window.cachedGroups);
+            let removed = false;
+            if (parsed.groups && parsed.groups[roomId]) {
+                delete parsed.groups[roomId];
+                removed = true;
+            }
+            //fallback: wpis może być zapisany z domena albo bez
+            if (!removed && parsed.groups && !roomId.includes(';')) {
+                for (let key in parsed.groups) {
+                    if (key.split(';')[0] === roomId) {
+                        delete parsed.groups[key];
+                        removed = true;
+                        break;
+                    }
+                }
+            }
+            if (removed) window.cachedGroups = JSON.stringify(parsed);
+            return removed;
+        } else {
+            if (!window.cachedDms) return false;
+            let parsed = JSON.parse(window.cachedDms);
+            if (parsed.dms && parsed.dms[roomId]) {
+                delete parsed.dms[roomId];
+                window.cachedDms = JSON.stringify(parsed);
+                return true;
+            }
+        }
+    } catch (e) {
+        console.error(e);
+    }
+    return false;
+}
+
+function removeRoomButton(roomId, type) {
+    let btn = document.getElementById(`${type === 'groups' ? 'group' : 'dm'}-btn-${sanitizeId(roomId)}`);
+    if (btn) btn.remove();
+}
+
+//Serwer informuje, że użytkownik został usunięty z grupy (kick) -
+//usuń grupę z listy, a jeśli jest otwarta, wyjdź z ekranu rozmowy.
+async function handleGroupRemoved(groupId) {
+    try {
+        removeRoomFromCachedList(groupId, 'groups');
+        removeRoomButton(sanitizeId(groupId), 'groups');
+        if (currentDmId === groupId || (currentDmId && currentDmId.split(';')[0] === groupId.split(';')[0] && window.currentRoomType === 'groups')) {
+            await handleLostRoomAccess(groupId, 'groups', "info:removed.from.group");
+        }
+        if (typeof refreshGroups === 'function') refreshGroups(0, false);
+    } catch (e) {
+        console.error(e);
+    }
+}
+
+//Pokój do którego straciliśmy dostęp: usuń go z listy i wyjdź z ekranu rozmowy.
+async function handleLostRoomAccess(roomId, type = null, notifyKey = null) {
+    if (!type) type = window.currentRoomType === 'groups' ? 'groups' : 'dms';
+    let wasOpen = currentDmId === roomId;
+
+    removeRoomFromCachedList(roomId, type);
+    removeRoomButton(sanitizeId(roomId), type);
+
+    if (typeof refreshDms === 'function') refreshDms(0, false);
+    if (typeof refreshGroups === 'function') refreshGroups(0, false);
+
+    if (wasOpen) {
+        showBlahNotification(notifyKey || (type === 'groups' ? "error:not.a.member" : "error:forbidden"));
+        if (dmMessagePollInterval) {
+            clearInterval(dmMessagePollInterval);
+            dmMessagePollInterval = null;
+        }
+        currentDmId = null;
+        window.currentRoomType = null;
+        if (mainScreen.classList.contains('mobile-details')) {
+            mainScreen.classList.remove('mobile-details');
+        }
+        gotoHome();
+    }
+}
+
 function updateDmListUI(roomId, isRead, type = 'dms', timestamp = null) {
     try {
         if (type === 'groups') {
@@ -5226,6 +5428,9 @@ function handleMemberContextMenu(e, groupId, memberId) {
     e.preventDefault();
     e.stopPropagation();
     
+    groupId = sanitizeId(groupId);
+    memberId = sanitizeId(memberId);
+    
     if (e && e.type === "contextmenu") {
         touchContextMenuFired = true;
         setTimeout(() => { touchContextMenuFired = false; }, 500);
diff --git a/webroot/style.css b/webroot/style.css
index 3247c504..6506b747 100644
--- a/webroot/style.css
+++ b/webroot/style.css
@@ -1418,10 +1418,16 @@ input:checked + .toggle-slider:before {
 .voice-resize-se { bottom: 0; right: 0; cursor: nwse-resize; }
 .voice-resize-sw { bottom: 0; left: 0; cursor: nesw-resize; }
 
+/*
+ * Kafelki rozmowy - wszystkie mają TEN SAM rozmiar (kwadrat, --voice-tile-size
+ * ustawiany przez relayoutVoiceTiles() w voice.js). Kafelki płyną obok siebie,
+ * a gdy się nie mieszczą w rzędzie, flex-wrap przenosi je do następnego.
+ */
 .voice-tile {
     position: relative;
-    width: var(--voice-tile-w, 9rem);
-    height: var(--voice-tile-h, 8rem);
+    width: var(--voice-tile-size, 9rem);
+    height: var(--voice-tile-size, 9rem);
+    flex: 0 0 auto;
     background: var(--light-border-color);
     background-size: cover;
     background-position: center;
@@ -1882,10 +1888,10 @@ input:checked + .toggle-slider:before {
     position: absolute;
     top: 0;
     bottom: 0;
-    width: 2px;
-    margin-left: -1px;
+    width: 0.125rem;
+    margin-left: -0.0625rem;
     background: rgba(255, 255, 255, 0.65);
-    border-radius: 1px;
+    border-radius: 0.0625rem;
     pointer-events: none;
 }
 /* Settings button keeps its hover look while the settings popup is open */
diff --git a/webroot/version.js b/webroot/version.js
index ca181587..98bb1f57 100644
--- a/webroot/version.js
+++ b/webroot/version.js
@@ -1 +1 @@
-const CLIENT_VERSION = "0.1.4";
+const CLIENT_VERSION = "0.2.0";
diff --git a/webroot/voice.js b/webroot/voice.js
index d4cf5d78..09dd8f0f 100644
--- a/webroot/voice.js
+++ b/webroot/voice.js
@@ -3,10 +3,99 @@ let currentVoiceCallId = null;
 let currentVoiceCallType = null;
 let voiceWsHeartbeat = null;
 let voiceActiveUsers = [];
-let voiceAesKeyBytes = null;
-let voiceAesCryptoKey = null;
+let voiceAesKeyBytes = null;      // grupowy klucz rozmowy (root) - dystrybuowany hybrydą PQ
 let voiceUiContainer = null;
 
+// === Gwarantowana unikalność IV (AES-GCM): ===
+// 1) każdy nadawca szyfruje WŁASNYM podkluczem HKDF(root, "larpix:voice:v1:"+senderId)
+//    -> kolizja między nadawcami niemożliwa z konstrukcji,
+// 2) IV(12B) = epoka(4B = SHA-256(ticketPublicId)[0..4]) || licznik(8B BE, ściśle rosnący)
+//    -> kolizja w ramach jednego nadawcy niemożliwa w obrębie epoki; każde dołączenie
+//    do calla ma unikalny ticketPublicId (single-use po stronie serwera), a licznik
+//    może się resetować TYLKO razem ze zmianą klucza root.
+let voiceMySenderCryptoKey = null;        // mój podklucz nadawcy (CryptoKey)
+const voicePeerSenderKeys = new Map();    // clientIdStr -> Promise<CryptoKey> odbiorczy
+let voiceSendEpoch = null;                // Uint8Array(4)
+let voiceSendCounter = 0n;                // BigInt, monotoniczny w ramach epoki
+
+//Promise rozstrzygany gdy operacja na kluczu root (ustawienie/wyczyszczenie)
+//jest gotowa - pozwala innym kodom czekać zamiast wchodzić w wyścig z derivacją.
+let voiceRootKeyReady = Promise.resolve();
+
+const VOICE_HKDF_INFO_PREFIX = "larpix:voice:v1:";
+
+function voiceHkdfInfoBytes(senderIdStr) {
+    const prefix = new TextEncoder().encode(VOICE_HKDF_INFO_PREFIX);
+    const idBytes = new TextEncoder().encode(String(senderIdStr));
+    const out = new Uint8Array(prefix.length + idBytes.length);
+    out.set(prefix, 0);
+    out.set(idBytes, prefix.length);
+    return out;
+}
+
+async function deriveVoiceSenderKey(rootBytes, senderIdStr) {
+    const ikm = await crypto.subtle.importKey("raw", rootBytes, "HKDF", false, ["deriveBits"]);
+    const bits = await crypto.subtle.deriveBits(
+        {name: "HKDF", hash: "SHA-256", salt: new Uint8Array(0), info: voiceHkdfInfoBytes(senderIdStr)},
+        ikm, 256
+    );
+    return await crypto.subtle.importKey("raw", new Uint8Array(bits), {name: "AES-GCM"}, false, ["encrypt", "decrypt"]);
+}
+
+//Jedyny punkt zmiany klucza root. Reset licznika jest poprawny wyłącznie tutaj -
+//nowy root = świeża przestrzeń IV. Null czyści cały stan.
+function setVoiceRootKey(bytesOrNull) {
+    const done = (async () => {
+        if (!bytesOrNull) {
+            voiceAesKeyBytes = null;
+            voiceMySenderCryptoKey = null;
+            voicePeerSenderKeys.clear();
+            return;
+        }
+        voicePeerSenderKeys.clear();
+        const k = await deriveVoiceSenderKey(bytesOrNull, String(window.id));
+        voiceAesKeyBytes = bytesOrNull;
+        voiceMySenderCryptoKey = k;
+    })();
+    voiceRootKeyReady = done;
+    return done;
+}
+
+//Epoka z unikalnego per-dołączenie ticketPublicId - deterministycznie, bez dodatkowego losowania.
+function setVoiceEpochFromTicket(publicIdB64u) {
+    crypto.subtle.digest("SHA-256", new TextEncoder().encode(String(publicIdB64u))).then(d => {
+        voiceSendEpoch = new Uint8Array(d).slice(0, 4);
+        voiceSendCounter = 0n;
+    }).catch(() => { voiceSendEpoch = null; voiceSendCounter = 0n; });
+}
+
+//Jedynne źródło IV do wysyłki. Inkrementacja synchroniczna (single-thread JS = atomiczne).
+function nextVoiceIv() {
+    if (!voiceSendEpoch) throw new Error("voice epoch not ready");
+    voiceSendCounter += 1n;
+    if (voiceSendCounter >= (1n << 63n)) throw new Error("voice iv counter exhausted"); //praktycznie nieosiągalne
+    const iv = new Uint8Array(12);
+    iv.set(voiceSendEpoch, 0);
+    let c = voiceSendCounter;
+    for (let i = 0; i < 8; i++) {
+        iv[11 - i] = Number(c & 0xffn);
+        c >>= 8n;
+    }
+    return iv;
+}
+
+//Podklucz odbiorczy danego nadawcy (cache). clientId to dziesiętny string ulonga - 
+//dokładnie ta sama forma, której nadawca użył przy derivacji własnego klucza.
+function getVoicePeerSenderKey(clientIdStr) {
+    let p = voicePeerSenderKeys.get(clientIdStr);
+    if (!p && voiceAesKeyBytes) {
+        p = deriveVoiceSenderKey(voiceAesKeyBytes, clientIdStr);
+        voicePeerSenderKeys.set(clientIdStr, p);
+    }
+    return p || null;
+}
+
+
 let micStream = null, audioContext = null, isAudioWorkletLoaded = false;
 let micSourceNode = null, senderNode = null, receiverNode = null, audioEncoder = null;
 let remoteAudio = {}, audioDecoders = {}, audioDecryptChains = {};
@@ -39,6 +128,8 @@ let peerLastSeen = {};
 let deadPeers = new Set();
 let lastVoiceServerPacketAt = 0;
 let voicePingTimer = null;
+let voiceRosterRetryTimer = null;
+let lastVoiceKeyRequestAt = 0;
 let voiceReconnectAttempts = 0;
 let voiceSocketOpenedAt = 0;
 
@@ -61,9 +152,9 @@ function cleanupPeerMedia(userId) {
 }
 
 function sendVoicePing() {
-    if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN || !voiceAesCryptoKey) return;
-    const iv = crypto.getRandomValues(new Uint8Array(12));
-    crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, new Uint8Array([Date.now() & 255])).then(cipher => {
+    if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN || !voiceMySenderCryptoKey) return;
+    const iv = nextVoiceIv();
+    crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, new Uint8Array([Date.now() & 255])).then(cipher => {
         if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN) return;
         const payload = new Uint8Array(14 + cipher.byteLength);
         payload[0] = 5; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
@@ -530,6 +621,16 @@ setInterval(() => {
         } else if (audioContext && audioContext.state === 'suspended') {
             audioContext.resume().catch(() => {});
         }
+        // Safety net for the call-key handshake: if others are in the call but
+        // we never received the root key (raced/lost signal), ask for it
+        // instead of staying deaf until someone refreshes the page.
+        if (others > 0 && !voiceAesKeyBytes && now - lastVoiceKeyRequestAt > 4000) {
+            lastVoiceKeyRequestAt = now;
+            console.debug("Voice: requesting call key from peers");
+            for (const u of voiceActiveUsers) {
+                if (u !== String(window.id)) sendVoiceSignalToUser(u, currentVoiceCallId, true);
+            }
+        }
     }
     if (changed) updateVoiceUIUsers();
 }, 2000);
@@ -682,6 +783,8 @@ async function requestVoiceJoin() {
 
     let serverUrl = parts[0];
     const [publicId, connKey, proof] = [parts[1], parts[2], parts[3]];
+    //epoka IV z unikalnego (single-use) publicId - każde dołączenie = rozłączna przestrzeń IV
+    setVoiceEpochFromTicket(publicId);
     if (!serverUrl.startsWith("ws://") && !serverUrl.startsWith("wss://")) {
         serverUrl = serverUrl.includes("localhost") || serverUrl.includes("127.0.0.1") ? "ws://" + serverUrl : "wss://" + serverUrl;
     }
@@ -780,7 +883,21 @@ async function startVoiceSession(serverUrl, ticket) {
                 } catch (e) {}
             };
             fetchUsers();
-            voiceWsHeartbeat = setInterval(fetchUsers, 5000);
+            //The voice-server roster is joined only AFTER ticket validation (an
+            //HTTP roundtrip to the main server), so the immediate fetch can still
+            //miss us - retry quickly until our own tile shows up instead of
+            //staring at an empty call for the first heartbeat.
+            if (voiceRosterRetryTimer) clearInterval(voiceRosterRetryTimer);
+            let rosterTries = 0;
+            voiceRosterRetryTimer = setInterval(() => {
+                if (!currentVoiceWs || currentVoiceWs.readyState !== WebSocket.OPEN ||
+                    voiceActiveUsers.includes(String(window.id)) || ++rosterTries > 12) {
+                    clearInterval(voiceRosterRetryTimer);
+                    voiceRosterRetryTimer = null;
+                    return;
+                }
+                fetchUsers();
+            }, 400);
 
             voiceReconnectAttempts = 0;
             lastVoiceServerPacketAt = Date.now();
@@ -847,9 +964,9 @@ async function startVoiceSession(serverUrl, ticket) {
                     if (micLevelBar) micLevelBar.style.backgroundColor = 'var(--big-green)';
                     if (vdsLevelFill) vdsLevelFill.style.backgroundColor = 'var(--big-green)';
                     
-                    if (!voiceAesCryptoKey) return;
-                    const iv = crypto.getRandomValues(new Uint8Array(12));
-                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, audioData);
+                    if (!voiceMySenderCryptoKey) return;
+                    const iv = nextVoiceIv();
+                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, audioData);
                     const payload = new Uint8Array(14 + cipher.byteLength);
                     payload[0] = 0; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
                     currentVoiceWs.send(payload.buffer);
@@ -886,7 +1003,10 @@ async function startVoiceSession(serverUrl, ticket) {
             const iv = new Uint8Array(arrayBuffer, 10, 12);
             const ciphertext = new Uint8Array(arrayBuffer, 22);
             
-            if (!voiceAesCryptoKey) return; 
+            if (!voiceAesKeyBytes) return; 
+
+            //podklucz nadawcy - deterministyczny z (root, clientId)
+            const senderKeyPromise = getVoicePeerSenderKey(clientId);
             
             if (type === 0 || type === 4) {
                 const isScreenAudio = (type === 4);
@@ -899,7 +1019,9 @@ async function startVoiceSession(serverUrl, ticket) {
                 const targetReceiver = isScreenAudio ? screenReceiverNode : receiverNode;
                 audioDecryptChains[audioId].enqueue(async () => {
                     try {
-                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, ciphertext);
+                        const senderKey = await senderKeyPromise;
+                        if (!senderKey) return;
+                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, senderKey, ciphertext);
                         if(targetReceiver) targetReceiver.port.postMessage({ clientId: audioId, audioData: decryptedBuffer }, [decryptedBuffer]);
 
                         setTileSpeaking(clientId, true, isScreenAudio ? `${clientId}-2` : null);
@@ -911,7 +1033,9 @@ async function startVoiceSession(serverUrl, ticket) {
                 
                 videoDecryptChains[decoderId].enqueue(async () => {
                     try {
-                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, ciphertext);
+                        const senderKey = await senderKeyPromise;
+                        if (!senderKey) return;
+                        const decryptedBuffer = await crypto.subtle.decrypt({name: "AES-GCM", iv}, senderKey, ciphertext);
                         
                         if (!remoteVideos[decoderId]) {
                             const canvas = document.createElement('canvas');
@@ -971,8 +1095,12 @@ async function startVoiceSession(serverUrl, ticket) {
                     } catch (err) {}
                 });
             } else if (type === 3) {
-                crypto.subtle.decrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, ciphertext).then(decrypted => {
-                    const stoppedTypeId = new Uint8Array(decrypted)[0];
+                (async () => {
+                    try {
+                        const senderKey = await senderKeyPromise;
+                        if (!senderKey) return;
+                        const decrypted = await crypto.subtle.decrypt({name: "AES-GCM", iv}, senderKey, ciphertext);
+                        const stoppedTypeId = new Uint8Array(decrypted)[0];
                     if (stoppedTypeId === 4) {
                         const audioId = `${clientId}_screen`;
                         if (remoteAudio[audioId]) {
@@ -989,7 +1117,8 @@ async function startVoiceSession(serverUrl, ticket) {
                             updateVoiceUIUsers();
                         }
                     }
-                 }).catch(() => {});
+                    } catch (err) {}
+                })();
             }
         };
         
@@ -1021,9 +1150,12 @@ async function startVoiceSession(serverUrl, ticket) {
     }
 }
 
-function handleCallUpdate(data) {
+async function handleCallUpdate(data) {
     let parts = data.split(":");
     let roomId = parts[1];
+    //Ignore updates for rooms we have nothing to do with - they would otherwise
+    //overwrite the participant list of an ongoing call and wipe its tiles.
+    if (roomId !== currentVoiceCallId && roomId !== window.currentDmId) return;
     let state = [];
     if(parts.slice(2).join(":") !== "") {
         let stateRaw = JSON.parse(parts.slice(2).join(":"));
@@ -1034,10 +1166,13 @@ function handleCallUpdate(data) {
     if (currentVoiceCallId === roomId) {
         let myIdStr = String(window.id);
         if (!voiceAesKeyBytes && state.length === 1 && state[0] === myIdStr) {
-            voiceAesKeyBytes = crypto.getRandomValues(new Uint8Array(32));
-            crypto.subtle.importKey("raw", voiceAesKeyBytes, {name: "AES-GCM"}, false, ["encrypt", "decrypt"])
-                .then(k => voiceAesCryptoKey = k);
+            setVoiceRootKey(crypto.getRandomValues(new Uint8Array(32)));
         }
+        //The root key is set asynchronously - wait for it before distributing.
+        //Otherwise a fast second join produces [me,peer] while the derivation
+        //is still running, no signal is sent and the peer never gets the key
+        //(audio stayed broken for everyone until someone refreshed the page).
+        await voiceRootKeyReady;
         if (voiceAesKeyBytes) {
             for (let u of state) {
                 if (u !== myIdStr) sendVoiceSignalToUser(u, roomId);
@@ -1120,7 +1255,7 @@ async function resolveCallerInfo(roomId) {
 }
 
 function showIncomingCallUI(roomId) {
-    if (document.getElementById("incoming-call-popup") || currentVoiceWs) return;
+    if (document.getElementById("incoming-call-popup") || currentVoiceWs || voiceJoinInFlight) return;
 
     let cachedName = window.dmUsernameCache ? window.dmUsernameCache[roomId] : null;
     if (cachedName && cachedName.includes(':')) cachedName = cachedName.split(':')[0];
@@ -1174,18 +1309,24 @@ function joinIncomingCall(roomId) {
     initiateVoiceCall(roomId);
 }
 
-async function sendVoiceSignalToUser(targetUserId, roomId) {
+async function sendVoiceSignalToUser(targetUserId, roomId, requestData = false) {
     try {
-        let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${targetUserId}`);
-        let publicKeys = JSON.parse(publicKeysRaw);
-        let hybrid = await deriveHybridKeyToUser(publicKeys);
-        
-        let encForMember = await encryptAesGcmToBase64(uint8ToBase64(voiceAesKeyBytes), hybrid.aesKeyBytes);
-        let setupPayloadJson = JSON.stringify({
-            v: 1,
-            ctMlKem: hybrid.ciphertextMlKemBase64,
-            enc: encForMember
-        });
+        let setupPayloadJson;
+        if (!requestData && voiceAesKeyBytes) {
+            let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${targetUserId}`);
+            let publicKeys = JSON.parse(publicKeysRaw);
+            let hybrid = await deriveHybridKeyToUser(publicKeys);
+
+            let encForMember = await encryptAesGcmToBase64(uint8ToBase64(voiceAesKeyBytes), hybrid.aesKeyBytes);
+            setupPayloadJson = JSON.stringify({
+                v: 1,
+                ctMlKem: hybrid.ciphertextMlKemBase64,
+                enc: encForMember
+            });
+        } else {
+            //Prośba o klucz rozmowy (bez sekretów) - adresat z kluczem odpowie pełnym sygnałem.
+            setupPayloadJson = JSON.stringify({ v: 1, needKey: true });
+        }
         
         let payload = JSON.stringify({
             string1: currentVoiceCallType,
@@ -1204,15 +1345,22 @@ async function handleRoomSignal(data) {
     let signalStr = parts.slice(2).join(":");
     let signalObj = JSON.parse(signalStr);
     
-    if (String(signalObj.to) === String(window.id) && roomId === currentVoiceCallId && !voiceAesKeyBytes) {
+    if (String(signalObj.to) === String(window.id) && roomId === currentVoiceCallId) {
         try {
             let setupData = JSON.parse(signalObj.data);
-            let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${signalObj.from}`); 
-            let otherPublicKeysObj = JSON.parse(publicKeysRaw);
-            let aesKeyBytes = await deriveHybridKeyFromSetup(otherPublicKeysObj, setupData.ctMlKem);
-            let decRoomKeyB64 = await decryptAesGcmFromBase64(setupData.enc, aesKeyBytes);
-            voiceAesKeyBytes = base64ToUint8(decRoomKeyB64);
-            voiceAesCryptoKey = await crypto.subtle.importKey("raw", voiceAesKeyBytes, {name: "AES-GCM"}, false, ["encrypt", "decrypt"]);
+            if (setupData.needKey) {
+                //Peer nie dostał klucza rozmowy (wygryziony/zagubiony sygnał) -
+                //odeślij mu go, ale tylko jeśli sami już go mamy.
+                if (voiceAesKeyBytes) await sendVoiceSignalToUser(signalObj.from, roomId);
+                return;
+            }
+            if (!voiceAesKeyBytes) {
+                let publicKeysRaw = await fetchAsync(`${url}/user/key/getpublic?id=${signalObj.from}`); 
+                let otherPublicKeysObj = JSON.parse(publicKeysRaw);
+                let aesKeyBytes = await deriveHybridKeyFromSetup(otherPublicKeysObj, setupData.ctMlKem);
+                let decRoomKeyB64 = await decryptAesGcmFromBase64(setupData.enc, aesKeyBytes);
+                await setVoiceRootKey(base64ToUint8(decRoomKeyB64));
+            }
         } catch(e) {
             console.error("Signal decryption failed", e);
         }
@@ -2038,6 +2186,12 @@ function ensureVoiceGridObserver() {
     voiceGridRO.observe(container);
 }
 
+/*
+ * Wszystkie kafelki to kwadraty o wspólnym rozmiarze --voice-tile-size.
+ * Wybieramy największy rozmiar kwadratu, przy którym n kafelków mieści się
+ * w oknie rozmowy - układanie i zawijanie do następnych rzędów robi sam
+ * flex-wrap w CSS (justify-content: center).
+ */
 function relayoutVoiceTiles() {
     let container = document.getElementById("voice-users");
     if (!container || !container.isConnected) return;
@@ -2052,28 +2206,34 @@ function relayoutVoiceTiles() {
     const innerH = container.clientHeight - parseFloat(cs.paddingTop) - parseFloat(cs.paddingBottom);
 
     if (!isFinite(innerW) || !isFinite(innerH) || !isFinite(rootFs) || innerW <= 0 || innerH <= 0 || rootFs <= 0) {
-        container.style.removeProperty("--voice-tile-w");
-        container.style.removeProperty("--voice-tile-h");
+        container.style.removeProperty("--voice-tile-size");
         delete container.dataset.layoutSig;
         return;
     }
 
-    const minCol = 6.25 * rootFs;
-    const minRow = 7 * rootFs;
     const gap = 0.75 * rootFs;
+    const maxSize = 18 * rootFs;   // jedna osoba nie dostanie gigantycznego kafelka
+    const minSize = 4.5 * rootFs;  // poniżej tego wolimy scrollować niż spłaszczać
 
-    const maxCols = Math.max(1, Math.floor((innerW + gap) / (minCol + gap)));
-    const cols = Math.min(n, maxCols);
-    const rows = Math.ceil(n / cols);
-    const w = Math.floor((innerW - gap * (cols - 1)) / cols);
-    const h = Math.floor(Math.max(minRow, (innerH - gap * (rows - 1)) / rows));
+    //Największy kwadrat, przy którym n kafelków mieści się w dostępnej powierzchni:
+    //próbujemy liczby kolumn 1..n, dla każdej wyliczamy ograniczony rozmiar
+    //(szerokość kolumny vs wysokość rzędu) i bierzemy najlepszy wariant.
+    let best = 0;
+    for (let cols = 1; cols <= n; cols++) {
+        const rows = Math.ceil(n / cols);
+        const s = Math.min(
+            (innerW - gap * (cols - 1)) / cols,
+            (innerH - gap * (rows - 1)) / rows
+        );
+        if (s > best) best = s;
+    }
 
-    const sig = `${n}:${cols}:${w}x${h}`;
+    const size = Math.min(maxSize, Math.max(minSize, Math.floor(best)));
+    const sig = `${n}:${size}`;
     if (container.dataset.layoutSig === sig) return;
     container.dataset.layoutSig = sig;
 
-    container.style.setProperty("--voice-tile-w", w + "px");
-    container.style.setProperty("--voice-tile-h", h + "px");
+    container.style.setProperty("--voice-tile-size", size + "px");
 }
 
 let voiceSettingsState = null;
@@ -2179,10 +2339,16 @@ function teardownVoiceTransport() {
     audioDecryptChains = {};
     peerLastSeen = {};
     deadPeers.clear();
+    if (voiceRosterRetryTimer) { clearInterval(voiceRosterRetryTimer); voiceRosterRetryTimer = null; }
+    lastVoiceKeyRequestAt = 0;
+    //Stale participants from the previous attempt must not linger in the UI
+    voiceActiveUsers = [];
+    updateVoiceUIUsers();
     if (receiverNode) receiverNode.port.postMessage({action: 'clear'});
     if (screenReceiverNode) screenReceiverNode.port.postMessage({action: 'clear'});
-    voiceAesKeyBytes = null;
-    voiceAesCryptoKey = null;
+    setVoiceRootKey(null);
+    voiceSendEpoch = null;
+    voiceSendCounter = 0n;
     lastVoiceServerPacketAt = Date.now();
 }
 
@@ -2243,8 +2409,11 @@ function endVoiceSession() {
     
     if (voiceWsHeartbeat) { clearInterval(voiceWsHeartbeat); voiceWsHeartbeat = null; }
     if (voicePingTimer) { clearInterval(voicePingTimer); voicePingTimer = null; }
+    if (voiceRosterRetryTimer) { clearInterval(voiceRosterRetryTimer); voiceRosterRetryTimer = null; }
     peerLastSeen = {};
     deadPeers.clear();
+    lastVoiceKeyRequestAt = 0;
+    voiceActiveUsers = [];
     
     for (let id in audioDecoders) {
         try { audioDecoders[id].close(); } catch(e){}
@@ -2275,8 +2444,9 @@ function endVoiceSession() {
     remoteVideos = {};
     videoDecryptChains = {};
     
-    voiceAesKeyBytes = null;
-    voiceAesCryptoKey = null;
+    setVoiceRootKey(null);
+    voiceSendEpoch = null;
+    voiceSendCounter = 0n;
     currentVoiceWs = null;
     currentVoiceCallType = null;
     currentVoiceCallId = null;
@@ -2322,11 +2492,11 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
                 screenAudioSourceNode = audioContext.createMediaStreamSource(stream);
                 screenSenderNode = new AudioWorkletNode(audioContext, 'audio-sender');
                 screenSenderNode.port.onmessage = async (e) => {
-                    if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceAesCryptoKey) return;
+                    if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceMySenderCryptoKey) return;
                     // Same backpressure valve as the mic sender.
                     if (currentVoiceWs.bufferedAmount > 256 * 1024) return;
-                    const iv = crypto.getRandomValues(new Uint8Array(12));
-                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, e.data.audioData);
+                    const iv = nextVoiceIv();
+                    const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, e.data.audioData);
                     const payload = new Uint8Array(14 + cipher.byteLength);
                     payload[0] = 4; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
                     currentVoiceWs.send(payload.buffer);
@@ -2357,10 +2527,10 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
         let currentConfig = getCurrentConfig(), isRunning = true, frameCount = 0;
         const encoder = new VideoEncoder({
             output: async (chunk) => {
-                if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceAesCryptoKey) return;
+                if (currentVoiceWs?.readyState !== WebSocket.OPEN || !voiceMySenderCryptoKey) return;
                 const buffer = new ArrayBuffer(chunk.byteLength); chunk.copyTo(buffer);
-                const iv = crypto.getRandomValues(new Uint8Array(12));
-                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, buffer);
+                const iv = nextVoiceIv();
+                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, buffer);
                 const payload = new Uint8Array(14 + cipher.byteLength);
                 payload[0] = typeId; payload[1] = chunk.type === 'key' ? 1 : 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14);
                 currentVoiceWs.send(payload.buffer);
@@ -2412,9 +2582,9 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
             updateVoiceUIUsers();
             btnEl.classList.remove('voice-btn-active');
 
-            if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceAesCryptoKey) {
-                const buffer = new Uint8Array([typeId]); const iv = crypto.getRandomValues(new Uint8Array(12));
-                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceAesCryptoKey, buffer);
+            if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceMySenderCryptoKey) {
+                const buffer = new Uint8Array([typeId]); const iv = nextVoiceIv();
+                const cipher = await crypto.subtle.encrypt({name: "AES-GCM", iv}, voiceMySenderCryptoKey, buffer);
                 const payload = new Uint8Array(14 + cipher.byteLength);
                 payload[0] = 3; payload[1] = 0; payload.set(iv, 2); payload.set(new Uint8Array(cipher), 14); currentVoiceWs.send(payload.buffer);
             }
@@ -2423,9 +2593,9 @@ async function startHardwareVideo(btnEl, streamPromise, typeLabel, typeId) {
                 if (screenAudioSourceNode) { screenAudioSourceNode.disconnect(); screenAudioSourceNode = null; }
                 if (screenSenderNode) { screenSenderNode.disconnect(); screenSenderNode = null; }
                 if (screenAudioEncoder) { try { screenAudioEncoder.close(); } catch (e) {} screenAudioEncoder = null; }
-                if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceAesCryptoKey) {
-                    const bufferAudioInfo = new Uint8Array([4]); const ivA = crypto.getRandomValues(new Uint8Array(12));
-                    const cipherA = await crypto.subtle.encrypt({name: "AES-GCM", iv: ivA}, voiceAesCryptoKey, bufferAudioInfo);
+                if (currentVoiceWs?.readyState === WebSocket.OPEN && voiceMySenderCryptoKey) {
+                    const bufferAudioInfo = new Uint8Array([4]); const ivA = nextVoiceIv();
+                    const cipherA = await crypto.subtle.encrypt({name: "AES-GCM", iv: ivA}, voiceMySenderCryptoKey, bufferAudioInfo);
                     const payloadA = new Uint8Array(14 + cipherA.byteLength);
                     payloadA[0] = 3; payloadA[1] = 0; payloadA.set(ivA, 2); payloadA.set(new Uint8Array(cipherA), 14); currentVoiceWs.send(payloadA.buffer);
                 }