diff --git a/CLAUDE.md b/CLAUDE.md
index 7bec40c..9a49076 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -429,11 +429,27 @@ Résout le cas "j'ai ajouté un mot de passe avec tri A-Z, où se loge-t-il ?"
 
 Une `vault_entries` row porte **plusieurs blobs chiffrés indépendants** :
 `encrypted_password/iv`, `totp_secret/totp_iv`, `custom_fields/custom_fields_iv`,
+**`username_enc/username_iv`** (métadonnée-at-rest, cf. plus bas),
 plus le champ-icône `icon_b64` et les méta non chiffrées (`site, title,
-username, folder, tags, kind, template`). `template` est le sous-type
+folder, tags, kind, template`). `template` est le sous-type
 (ex: `credit-card`, `ssh-key`, `server`, `recovery-codes`) qui drive le
 label de card/table — vide pour login/note génériques.
 
+**`username` chiffré (§1.3)** : la colonne `username` en clair est en voie
+d'extinction — les nouvelles écritures y mettent `''` et rangent le chiffré
+dans `username_enc/username_iv` (AES-GCM sous la clé du vault, comme
+`encrypted_password`). `loadEntries`/`loadTrash` déchiffrent → `e.username`
+en mémoire, donc **recherche/tri/render/autofill-match marchent inchangés**
+(tout est déjà côté client). Choke-point d'écriture : `withEncryptedUsername(obj)`
+(chiffre `obj.username`, blanchit le clair) — enveloppe **chaque** body
+POST/PUT `/entries` (saveEntry, soSave, duplicateEntry, moveEntryToFolder,
+addTagToEntry, batchMove/AddTag, encryptImportEntry, migration). Anciennes
+lignes migrées au unlock par `migrateUsernamesAtRest` (PUT re-ship, bump
+`updated_at` assumé une fois). Rotation master-pw re-chiffre `username_enc`
+sous la nouvelle clé (JS loop + UPDATE serveur). Le `?q=` serveur ne LIKE
+plus que `site`. `site`/`title`/`tags` restent en clair (à chiffrer plus
+tard, même patron — cf. [[encrypt-metadata-plan]]).
+
 Quand tu ajoutes un nouveau champ (chiffré ou non), il faut **toujours**
 mettre à jour ces 6 endroits sous peine de perdre la donnée silencieusement
 sur certaines actions :
diff --git a/CODE_AUDIT.md b/CODE_AUDIT.md
index 6b80146..3e72fe1 100644
--- a/CODE_AUDIT.md
+++ b/CODE_AUDIT.md
@@ -85,12 +85,19 @@ Documenté mais à rappeler pour un futur modèle de menace :
 
 - `entry_attachments` : `filename`, `mime`, `size_bytes` **non chiffrés**
 - `users.avatar_b64` : image **non chiffrée** (cosmétique, assumé)
-- `vault_entries` : `site`, `title`, `username`, `folder`, `tags`, `kind`,
-  `template` **non chiffrés** (nécessaire pour recherche/tri sans déchiffrer)
+- `vault_entries` : ~~`username`~~ **chiffré (2026-07-08)** ; `site`, `title`,
+  `folder`, `tags`, `kind`, `template` encore en clair.
 
-Un attaquant avec accès disque voit la liste des sites et usernames. Pour
-un vault perso c'est un compromis acceptable (recherche instantanée), mais
-à documenter clairement pour l'utilisateur.
+**`username` chiffré au repos (✅ 2026-07-08)** : colonnes
+`username_enc/username_iv` (AES-GCM sous la clé du vault). Clé de l'approche :
+recherche/tri sont **côté client** → on déchiffre au `loadEntries` en mémoire,
+donc AES-GCM plein (IV aléatoire), pas de searchable-encryption. Choke-point
+`withEncryptedUsername` sur tous les writes ; migration `migrateUsernamesAtRest`
+au unlock pour les vieilles lignes ; rotation re-chiffre. Détails dans
+CLAUDE.md « Entry payload ». **Reste** : `site`/`title`/`tags` (même patron,
+[[encrypt-metadata-plan]]). Résiduel : nombre de lignes, timestamps, métadonnées
+d'attachments. **Non compilé/testé runtime Delphi cette session** —
+gros changement multi-handlers, rebuild + test soigneux requis.
 
 ### 1.4 🟡 Snapshot de sync = tout le vault en clair sous le sync password
 
diff --git a/delphi-backend/Handlers/PM.Handler.Auth.pas b/delphi-backend/Handlers/PM.Handler.Auth.pas
index 39bb040..ffb831b 100644
--- a/delphi-backend/Handlers/PM.Handler.Auth.pas
+++ b/delphi-backend/Handlers/PM.Handler.Auth.pas
@@ -1040,6 +1040,7 @@ begin
             '  encrypted_password = :ep, iv = :iv, ' +
             '  totp_secret = :ts, totp_iv = :tiv, ' +
             '  custom_fields = :cf, custom_fields_iv = :cfiv, ' +
+            '  username_enc = :uenc, username_iv = :uiv, ' +
             '  updated_at = CURRENT_TIMESTAMP ' +
             'WHERE id = :id AND user_id = :uid';
 
@@ -1053,6 +1054,8 @@ begin
             LTotpIv  := LEntry.GetValue<string>('totp_iv', '');
             var LCf   := LEntry.GetValue<string>('custom_fields', '');
             var LCfIv := LEntry.GetValue<string>('custom_fields_iv', '');
+            var LUEnc := LEntry.GetValue<string>('username_enc', '');
+            var LUIv  := LEntry.GetValue<string>('username_iv', '');
             if (LEntryId <= 0) or (LEncPwd = '') or (LIv = '') then
               raise Exception.CreateFmt('Invalid entry payload at index %d', [I]);
 
@@ -1074,6 +1077,12 @@ begin
             else              LQ.ParamByName('cf').Value := LCf;
             if LCfIv = '' then LQ.ParamByName('cfiv').Clear
             else                LQ.ParamByName('cfiv').Value := LCfIv;
+            LQ.ParamByName('uenc').DataType := ftMemo;
+            LQ.ParamByName('uiv').DataType  := ftMemo;
+            if LUEnc = '' then LQ.ParamByName('uenc').Clear
+            else               LQ.ParamByName('uenc').Value := LUEnc;
+            if LUIv = '' then LQ.ParamByName('uiv').Clear
+            else              LQ.ParamByName('uiv').Value := LUIv;
             LQ.ExecSQL;
           end;
           // Password history is encrypted with the OLD vault key — we
diff --git a/delphi-backend/Handlers/PM.Handler.Entries.pas b/delphi-backend/Handlers/PM.Handler.Entries.pas
index d1dc5cb..e182319 100644
--- a/delphi-backend/Handlers/PM.Handler.Entries.pas
+++ b/delphi-backend/Handlers/PM.Handler.Entries.pas
@@ -88,7 +88,9 @@ begin
         LQ.SQL.Text :=
           'SELECT * FROM vault_entries ' +
           'WHERE user_id = :uid AND deleted = :del ' +
-          'AND (site LIKE :q OR username LIKE :q) ' +
+          // username is encrypted at rest → LIKE can't match it; the frontend
+          // searches client-side on the decrypted vault anyway. Site only.
+          'AND site LIKE :q ' +
           'ORDER BY updated_at DESC';
         LQ.ParamByName('q').AsString := '%' + LSearch + '%';
       end
@@ -108,7 +110,20 @@ begin
         LObj.AddPair('id', TJSONNumber.Create(LQ.FieldByName('id').AsInteger));
         LObj.AddPair('site', LQ.FieldByName('site').AsString);
         LObj.AddPair('title', LQ.FieldByName('title').AsString);
+        // Cleartext username: '' for migrated rows (ciphertext lives in
+        // username_enc). Old rows still carry it until the client sweep.
         LObj.AddPair('username', LQ.FieldByName('username').AsString);
+        // Encrypted username (AES-GCM under the vault key). NULL → JSON null
+        // so the client knows the row isn't migrated yet and falls back to
+        // the cleartext `username` above.
+        if LQ.FieldByName('username_enc').IsNull then
+          LObj.AddPair('username_enc', TJSONNull.Create)
+        else
+          LObj.AddPair('username_enc', LQ.FieldByName('username_enc').AsString);
+        if LQ.FieldByName('username_iv').IsNull then
+          LObj.AddPair('username_iv', TJSONNull.Create)
+        else
+          LObj.AddPair('username_iv', LQ.FieldByName('username_iv').AsString);
         LObj.AddPair('encrypted_password', LQ.FieldByName('encrypted_password').AsString);
         LObj.AddPair('iv', LQ.FieldByName('iv').AsString);
         LObj.AddPair('encryption_method', LQ.FieldByName('encryption_method').AsString);
@@ -300,8 +315,8 @@ procedure HandleCreateEntry(ARequest: TIdHTTPRequestInfo;
 var
   LUserId, LNewId: Integer;
   LBody, LObj: TJSONObject;
-  LSite, LTitle, LUser, LFolder, LEnc, LIV, LTags, LNow, LTotpSec, LTotpIv,
-    LKind, LCf, LCfIv, LIcon, LTemplate, LUuid: string;
+  LSite, LTitle, LUser, LUserEnc, LUserIv, LFolder, LEnc, LIV, LTags, LNow,
+    LTotpSec, LTotpIv, LKind, LCf, LCfIv, LIcon, LTemplate, LUuid: string;
   LQ: TFDQuery;
 begin
   try
@@ -316,6 +331,11 @@ begin
     LSite    := Trim(LBody.GetValue<string>('site', ''));
     LTitle   := Trim(LBody.GetValue<string>('title', ''));
     LUser    := Trim(LBody.GetValue<string>('username', ''));
+    // Encrypted username (metadata-at-rest). When present the client has
+    // already wiped the cleartext `username` to '' — the ciphertext is stored
+    // in username_enc/username_iv instead.
+    LUserEnc := LBody.GetValue<string>('username_enc', '');
+    LUserIv  := LBody.GetValue<string>('username_iv', '');
     LFolder  := Trim(LBody.GetValue<string>('folder', 'All'));
     LEnc     := LBody.GetValue<string>('encrypted_password', '');
     LIV      := LBody.GetValue<string>('iv', '');
@@ -359,15 +379,22 @@ begin
       LQ.Connection := DB.Connection;
       LQ.SQL.Text :=
         'INSERT INTO vault_entries ' +
-        '(user_id, site, title, username, encrypted_password, iv, encryption_method, ' +
+        '(user_id, site, title, username, username_enc, username_iv, ' +
+        ' encrypted_password, iv, encryption_method, ' +
         ' folder, tags, totp_secret, totp_iv, kind, custom_fields, custom_fields_iv,' +
         ' icon_b64, template, uuid, created_at, updated_at, password_changed_at) ' +
-        'VALUES (:uid, :s, :tt, :u, :e, :i, ''client'', :f, :t, :ts, :tiv, :k, ' +
+        'VALUES (:uid, :s, :tt, :u, :uenc, :uiv, :e, :i, ''client'', :f, :t, :ts, :tiv, :k, ' +
         ' :cf, :cfiv, :ic, :tpl, :uuid, :c, :c2, :c)';
       LQ.ParamByName('uid').AsInteger := LUserId;
       LQ.ParamByName('s').AsString  := LSite;
       LQ.ParamByName('tt').AsString := LTitle;
       LQ.ParamByName('u').AsString  := LUser;
+      // Encrypted username: NULL when not supplied (pre-migration client or a
+      // row that genuinely has no username) so GET emits JSON null.
+      LQ.ParamByName('uenc').DataType := ftMemo;
+      LQ.ParamByName('uiv').DataType  := ftMemo;
+      if LUserEnc = '' then LQ.ParamByName('uenc').Clear else LQ.ParamByName('uenc').Value := LUserEnc;
+      if LUserIv  = '' then LQ.ParamByName('uiv').Clear  else LQ.ParamByName('uiv').Value  := LUserIv;
       LQ.ParamByName('e').AsString  := LEnc;
       LQ.ParamByName('i').AsString  := LIV;
       LQ.ParamByName('f').AsString  := LFolder;
@@ -439,8 +466,8 @@ procedure HandleUpdateEntry(ARequest: TIdHTTPRequestInfo;
 var
   LUserId, LId: Integer;
   LBody: TJSONObject;
-  LSite, LTitle, LUser, LFolder, LEnc, LIV, LTags, LNow, LTotpSec, LTotpIv,
-    LKind, LCf, LCfIv, LTemplate: string;
+  LSite, LTitle, LUser, LUserEnc, LUserIv, LFolder, LEnc, LIV, LTags, LNow,
+    LTotpSec, LTotpIv, LKind, LCf, LCfIv, LTemplate: string;
   LHasTemplate: Boolean;
   LQ: TFDQuery;
 begin
@@ -463,6 +490,8 @@ begin
     LSite    := Trim(LBody.GetValue<string>('site', ''));
     LTitle   := Trim(LBody.GetValue<string>('title', ''));
     LUser    := Trim(LBody.GetValue<string>('username', ''));
+    LUserEnc := LBody.GetValue<string>('username_enc', '');
+    LUserIv  := LBody.GetValue<string>('username_iv', '');
     LFolder  := Trim(LBody.GetValue<string>('folder', 'All'));
     LEnc     := LBody.GetValue<string>('encrypted_password', '');
     LIV      := LBody.GetValue<string>('iv', '');
@@ -532,7 +561,8 @@ begin
       if LHasTemplate then LTemplateSet := ', template=:tpl';
       LQ.SQL.Text :=
         'UPDATE vault_entries ' +
-        'SET site=:s, title=:tt, username=:u, encrypted_password=:e, iv=:i, ' +
+        'SET site=:s, title=:tt, username=:u, username_enc=:uenc, username_iv=:uiv, ' +
+        '    encrypted_password=:e, iv=:i, ' +
         '    folder=:f, tags=:t, totp_secret=:ts, totp_iv=:tiv, kind=:k, ' +
         '    custom_fields=:cf, custom_fields_iv=:cfiv, ' +
         '    updated_at=:c, ' +
@@ -543,6 +573,10 @@ begin
       LQ.ParamByName('s').AsString    := LSite;
       LQ.ParamByName('tt').AsString   := LTitle;
       LQ.ParamByName('u').AsString    := LUser;
+      LQ.ParamByName('uenc').DataType := ftMemo;
+      LQ.ParamByName('uiv').DataType  := ftMemo;
+      if LUserEnc = '' then LQ.ParamByName('uenc').Clear else LQ.ParamByName('uenc').Value := LUserEnc;
+      if LUserIv  = '' then LQ.ParamByName('uiv').Clear  else LQ.ParamByName('uiv').Value  := LUserIv;
       LQ.ParamByName('e').AsString    := LEnc;
       LQ.ParamByName('i').AsString    := LIV;
       LQ.ParamByName('f').AsString    := LFolder;
@@ -1113,8 +1147,8 @@ var
   LUserId, I, LImported, LNewId: Integer;
   LBody, LObj, LEntry: TJSONObject;
   LArr, LIds: TJSONArray;
-  LSite, LTitle, LUser, LFolder, LEnc, LIV, LTags, LTotpSec, LTotpIv, LNow,
-    LKind, LCf, LCfIv, LIcon, LTemplate, LUuid: string;
+  LSite, LTitle, LUser, LUserEnc, LUserIv, LFolder, LEnc, LIV, LTags, LTotpSec,
+    LTotpIv, LNow, LKind, LCf, LCfIv, LIcon, LTemplate, LUuid: string;
   LQ, LTomb: TFDQuery;
 begin
   try
@@ -1167,10 +1201,11 @@ begin
             'WHERE user_id = :uid AND uuid = :uuid';
           LQ.SQL.Text :=
             'INSERT INTO vault_entries ' +
-            '(user_id, site, title, username, encrypted_password, iv, encryption_method, ' +
+            '(user_id, site, title, username, username_enc, username_iv, ' +
+            ' encrypted_password, iv, encryption_method, ' +
             ' folder, tags, totp_secret, totp_iv, kind, custom_fields, custom_fields_iv,' +
             ' icon_b64, template, uuid, created_at, updated_at) ' +
-            'VALUES (:uid, :s, :tt, :u, :e, :i, ''client'', :f, :t, :ts, :tiv, :k, ' +
+            'VALUES (:uid, :s, :tt, :u, :uenc, :uiv, :e, :i, ''client'', :f, :t, :ts, :tiv, :k, ' +
             ' :cf, :cfiv, :ic, :tpl, :uuid, :c, :c2)';
           // Declare optional param types ONCE — the prepared statement is
           // reused across every imported entry, and FireDAC needs the
@@ -1186,6 +1221,8 @@ begin
           LQ.ParamByName('cfiv').DataType := ftMemo;
           LQ.ParamByName('ic').DataType   := ftMemo;
           LQ.ParamByName('tpl').DataType  := ftString;
+          LQ.ParamByName('uenc').DataType := ftMemo;
+          LQ.ParamByName('uiv').DataType  := ftMemo;
 
           for I := 0 to LArr.Count - 1 do
           begin
@@ -1193,6 +1230,8 @@ begin
             LSite    := Trim(LEntry.GetValue<string>('site', ''));
             LTitle   := Trim(LEntry.GetValue<string>('title', ''));
             LUser    := Trim(LEntry.GetValue<string>('username', ''));
+            LUserEnc := LEntry.GetValue<string>('username_enc', '');
+            LUserIv  := LEntry.GetValue<string>('username_iv', '');
             LFolder  := Trim(LEntry.GetValue<string>('folder', 'All'));
             LEnc     := LEntry.GetValue<string>('encrypted_password', '');
             LIV      := LEntry.GetValue<string>('iv', '');
@@ -1227,6 +1266,8 @@ begin
             LQ.ParamByName('s').AsString  := LSite;
             LQ.ParamByName('tt').AsString := LTitle;
             LQ.ParamByName('u').AsString  := LUser;
+            if LUserEnc = '' then LQ.ParamByName('uenc').Clear else LQ.ParamByName('uenc').Value := LUserEnc;
+            if LUserIv  = '' then LQ.ParamByName('uiv').Clear  else LQ.ParamByName('uiv').Value  := LUserIv;
             LQ.ParamByName('e').AsString  := LEnc;
             LQ.ParamByName('i').AsString  := LIV;
             LQ.ParamByName('f').AsString  := LFolder;
diff --git a/delphi-backend/Source/PM.Database.pas b/delphi-backend/Source/PM.Database.pas
index d251efb..59977b7 100644
--- a/delphi-backend/Source/PM.Database.pas
+++ b/delphi-backend/Source/PM.Database.pas
@@ -353,6 +353,14 @@ begin
   // columns as opaque ciphertext + IV.
   AddColumnIfMissing('vault_entries', 'custom_fields',     'TEXT');
   AddColumnIfMissing('vault_entries', 'custom_fields_iv',  'TEXT');
+  // Encrypted username (AES-GCM under the vault key, same as encrypted_password).
+  // Metadata-at-rest hardening (CODE_AUDIT §1.3): the cleartext `username`
+  // column is phased out — new writes store '' there and put the ciphertext
+  // here. Old rows keep cleartext until the client migration sweep re-encrypts
+  // them at unlock. Search/sort stay client-side on the decrypted in-memory
+  // value, so no server-side change to those. NULL = not yet encrypted.
+  AddColumnIfMissing('vault_entries', 'username_enc',      'TEXT');
+  AddColumnIfMissing('vault_entries', 'username_iv',       'TEXT');
   // Cached favicon as a base64 data URI (e.g. "data:image/png;base64,...").
   // Fetched on demand by the Delphi favicon proxy when the user opts in.
   // NULL = no icon cached → JS falls back to the first-letter avatar.
diff --git a/js/app.import.js b/js/app.import.js
index 9ddb56e..d6b8e5b 100644
--- a/js/app.import.js
+++ b/js/app.import.js
@@ -454,7 +454,9 @@ async function encryptImportEntry(plain) {
     const tagsStr = Array.isArray(plain.tags)
         ? plain.tags.filter(Boolean).join(',')
         : (plain.tags || '');
-    return {
+    // Encrypt the username at rest (username_enc/username_iv, cleartext blanked)
+    // via the shared choke point in app.js — same as the interactive save path.
+    return await withEncryptedUsername({
         uuid:               plain.uuid || '',
         site:               plain.site,
         title:              plain.title || '',
@@ -470,7 +472,7 @@ async function encryptImportEntry(plain) {
         custom_fields_iv:   cfIv,
         icon_b64:           plain.icon_b64 || '',
         template:           plain.template || '',
-    };
+    });
 }
 
 // Open a hidden file picker, route the result through the right parser,
diff --git a/js/app.js b/js/app.js
index e6f5aaa..08baa44 100644
--- a/js/app.js
+++ b/js/app.js
@@ -1468,10 +1468,82 @@ function folderMetaFor(name) {
     return { color: (f && f.color) || '', icon: (f && f.icon) || '' };
 }
 
+// Metadata-at-rest: username is stored encrypted (username_enc/username_iv).
+// Decrypt it into e.username in place so all downstream code (render, search,
+// autofill-match, sort) works on the plaintext transparently — exactly as
+// when username was a cleartext column. Rows not yet migrated have no
+// username_enc → their cleartext e.username is kept as-is (fallback).
+async function decryptEntryUsernames(list) {
+    for (const e of (list || [])) {
+        if (e && e.username_enc && e.username_iv) {
+            const u = await decryptPwd(e.username_enc, e.username_iv);
+            if (u !== '[ERROR]') e.username = u;
+        }
+    }
+}
+
+// Choke point for the write path: take an entry body object whose `username`
+// holds PLAINTEXT, encrypt it into username_enc/username_iv, and blank the
+// cleartext field so nothing readable is persisted. Wrap every POST/PUT
+// /entries body in this. Empty username → all cleared (server stores NULL
+// ciphertext + '' username). Mutates + returns the object for convenience.
+async function withEncryptedUsername(obj) {
+    const plain = (obj && obj.username) || '';
+    if (plain) {
+        const c = await encryptPwd(plain);
+        obj.username_enc = c.encrypted;
+        obj.username_iv  = c.iv;
+    } else {
+        obj.username_enc = '';
+        obj.username_iv  = '';
+    }
+    obj.username = '';
+    return obj;
+}
+
+// One-time sweep: re-save (full re-ship PUT) every entry that still carries a
+// cleartext username with no ciphertext yet, so the cleartext is wiped from
+// the DB. Runs at enterApp; no-op once every row is migrated. Best-effort —
+// individual failures are skipped and retried on the next unlock. The PUT
+// bumps updated_at (accepted one-time sync churn; the plaintext is unchanged
+// so other devices converge to the same value).
+async function migrateUsernamesAtRest() {
+    if (!state.cryptoKey) return;
+    const todo = state.entries.filter(e => e && !e.username_enc && (e.username || '') !== '');
+    if (todo.length === 0) return;
+    let migrated = 0;
+    for (const e of todo) {
+        try {
+            await api('/entries/' + e.id, {
+                method: 'PUT',
+                headers: authHeaders({ 'Content-Type': 'application/json' }),
+                body: JSON.stringify(await withEncryptedUsername({
+                    site:               e.site,
+                    title:              e.title || '',
+                    username:           e.username,
+                    encrypted_password: e.encrypted_password,
+                    iv:                 e.iv,
+                    folder:             e.folder,
+                    tags:               e.tags || '',
+                    kind:               e.kind || 'login',
+                    totp_secret:        e.totp_secret      || '',
+                    totp_iv:            e.totp_iv          || '',
+                    custom_fields:      e.custom_fields    || '',
+                    custom_fields_iv:   e.custom_fields_iv || '',
+                    template:           e.template || '',
+                })),
+            });
+            migrated++;
+        } catch (_) { /* retry next unlock */ }
+    }
+    if (migrated > 0) await loadEntries();
+}
+
 async function loadEntries() {
     try {
         const r = await api('/entries', { headers: authHeaders() });
         state.entries = Array.isArray(r) ? r : [];
+        await decryptEntryUsernames(state.entries);
     } catch (e) {
         if (e.message === 'Invalid session' || e.message === 'Session expired') {
             return doLogout();
@@ -1484,6 +1556,7 @@ async function loadTrash() {
     try {
         const r = await api('/entries?deleted=1', { headers: authHeaders() });
         state.trashed = Array.isArray(r) ? r : [];
+        await decryptEntryUsernames(state.trashed);
         state.trashedCount = state.trashed.length;
     } catch (e) { state.trashed = []; }
 }
@@ -2148,7 +2221,7 @@ async function addTagToEntry(id, tag) {
         await api('/entries/' + id, {
             method: 'PUT',
             headers: authHeaders({ 'Content-Type': 'application/json' }),
-            body: JSON.stringify({
+            body: JSON.stringify(await withEncryptedUsername({
                 site:               e.site,
                 title:              e.title || '',
                 username:           e.username,
@@ -2161,7 +2234,7 @@ async function addTagToEntry(id, tag) {
                 totp_iv:            e.totp_iv          || '',
                 custom_fields:      e.custom_fields    || '',
                 custom_fields_iv:   e.custom_fields_iv || '',
-            }),
+            })),
         });
         e.tags = tags.join(',');
         render();
@@ -3423,11 +3496,11 @@ async function batchMoveToFolder(folder) {
             await api('/entries/' + id, {
                 method: 'PUT',
                 headers: authHeaders({ 'Content-Type': 'application/json' }),
-                body: JSON.stringify({
+                body: JSON.stringify(await withEncryptedUsername({
                     // Re-ship the full payload — partial PUT would wipe
-                    // TOTP / custom_fields / kind / template (see also
-                    // moveEntryToFolder and the "places à toucher" list
-                    // in CLAUDE.md).
+                    // TOTP / custom_fields / kind / template / username_enc
+                    // (see also moveEntryToFolder and the "places à toucher"
+                    // list in CLAUDE.md).
                     site:               e.site,
                     title:              e.title || '',
                     username:           e.username,
@@ -3440,7 +3513,7 @@ async function batchMoveToFolder(folder) {
                     totp_iv:            e.totp_iv          || '',
                     custom_fields:      e.custom_fields    || '',
                     custom_fields_iv:   e.custom_fields_iv || '',
-                }),
+                })),
             });
             e.folder = folder;
         } catch (err) { /* ignore individual failures */ }
@@ -3464,7 +3537,7 @@ async function batchAddTag(tag) {
             await api('/entries/' + id, {
                 method: 'PUT',
                 headers: authHeaders({ 'Content-Type': 'application/json' }),
-                body: JSON.stringify({
+                body: JSON.stringify(await withEncryptedUsername({
                     site:               e.site,
                     title:              e.title || '',
                     username:           e.username,
@@ -3477,7 +3550,7 @@ async function batchAddTag(tag) {
                     totp_iv:            e.totp_iv          || '',
                     custom_fields:      e.custom_fields    || '',
                     custom_fields_iv:   e.custom_fields_iv || '',
-                }),
+                })),
             });
             e.tags = tags.join(',');
         } catch (err) {}
@@ -4665,7 +4738,7 @@ async function soSave() {
         cfIv  = e.iv;
     }
 
-    const body = JSON.stringify({
+    const body = JSON.stringify(await withEncryptedUsername({
         site, title: title.trim(), username: user,
         encrypted_password: enc.encrypted, iv: enc.iv,
         totp_secret: totpEnc, totp_iv: totpIv,
@@ -4673,7 +4746,7 @@ async function soSave() {
         folder: fold, tags: soState.tags.join(','),
         kind,
         template: soState.template || '',
-    });
+    }));
 
     try {
         let targetId = soState.id;
@@ -4993,10 +5066,10 @@ async function saveEntry(e) {
     if (!site || !pwd) return toast('Site and password required', 'error');
 
     const enc = await encryptPwd(pwd);
-    const body = JSON.stringify({
+    const body = JSON.stringify(await withEncryptedUsername({
         site, title, username: user, encrypted_password: enc.encrypted, iv: enc.iv,
         folder: fold, tags,
-    });
+    }));
     try {
         let savedId = id ? parseInt(id) : null;
         if (id) {
@@ -5089,7 +5162,7 @@ async function duplicateEntry(entry) {
         const r = await api('/entries', {
             method: 'POST',
             headers: authHeaders({ 'Content-Type': 'application/json' }),
-            body: JSON.stringify({
+            body: JSON.stringify(await withEncryptedUsername({
                 site:               entry.site || '',
                 title:              entryDisplayName(entry) + ' (copy)',
                 username:           entry.username || '',
@@ -5114,7 +5187,7 @@ async function duplicateEntry(entry) {
                 // Carry the template identifier so the copy keeps the
                 // same card / table label as the source.
                 template:           entry.template || '',
-            }),
+            })),
         });
 
         // Copy attachments. The source's encrypted blobs are keyed to the
@@ -5253,7 +5326,7 @@ async function moveEntryToFolder(id, folder) {
         await api('/entries/' + id, {
             method: 'PUT',
             headers: authHeaders({ 'Content-Type': 'application/json' }),
-            body: JSON.stringify({
+            body: JSON.stringify(await withEncryptedUsername({
                 site:               e.site,
                 title:              e.title || '',
                 username:           e.username,
@@ -5266,7 +5339,7 @@ async function moveEntryToFolder(id, folder) {
                 totp_iv:            e.totp_iv          || '',
                 custom_fields:      e.custom_fields    || '',
                 custom_fields_iv:   e.custom_fields_iv || '',
-            }),
+            })),
         });
         e.folder = folder;
         render();
@@ -7096,6 +7169,14 @@ async function doChangeMasterPassword() {
                         cfIv  = c.iv;
                     }
                 }
+                // Username is encrypted at rest too — re-encrypt the plaintext
+                // (e.username was decrypted at load) under the NEW key.
+                let uEnc = '', uIv = '';
+                if (e.username) {
+                    state.cryptoKey = newKey;
+                    const u = await encryptPwd(e.username);
+                    uEnc = u.encrypted; uIv = u.iv;
+                }
                 encrypted.push({
                     id:                 e.id,
                     encrypted_password: re.encrypted,
@@ -7104,6 +7185,8 @@ async function doChangeMasterPassword() {
                     totp_iv:            totpIv,
                     custom_fields:      cfEnc,
                     custom_fields_iv:   cfIv,
+                    username_enc:       uEnc,
+                    username_iv:        uIv,
                 });
             } finally {
                 state.cryptoKey = oldKey; // restore until server confirms
@@ -7877,6 +7960,10 @@ async function enterApp() {
     await loadEntryCounts();
     render();
     resetAutoLock();
+    // One-time metadata-at-rest migration: encrypt the cleartext username of
+    // any row that predates the encrypted column. Fire-and-forget so it never
+    // blocks the UI; each pass shrinks the backlog until nothing's left.
+    migrateUsernamesAtRest();
     // Fire-and-forget HIBP scan if the user opted in. Runs in background,
     // re-renders when done to show badges.
     if (state.hibpEnabled) hibpCheckAllEntries();
diff --git a/js/tests/merge.test.js b/js/tests/merge.test.js
index c8223e2..17a6514 100644
--- a/js/tests/merge.test.js
+++ b/js/tests/merge.test.js
@@ -110,6 +110,12 @@ test('merge: remote-only entry is added locally, keeping its uuid', async () =>
     assert.equal(res.updated, 0);
     assert.equal(db.entries.length, 1);
     assert.equal(db.entries[0].uuid, 'uuid-new');
+    // Metadata-at-rest: username is encrypted on the way in — the stored row
+    // carries ciphertext + a blank cleartext field, never the plaintext.
+    assert.equal(db.entries[0].username, '', 'cleartext username must be blanked');
+    assert.ok(db.entries[0].username_enc, 'username_enc must be present');
+    assert.ok(db.entries[0].username_iv, 'username_iv must be present');
+    assert.notEqual(db.entries[0].username_enc, 'u', 'must not store plaintext');
     assert.equal(db.entries[0].site, 'https://new.example');
 });