fix(recovery): don't commit the code until the user saves it

Generating a recovery code POSTed /recovery-key/setup — which deletes any
existing recovery row and inserts the new one — BEFORE showing the code. So
cancelling the "save this code" modal still erased the old code and activated
a new one the user never saw: a silent path to lockout.

Generate + wrap locally, show the code, and only POST setup after "I saved
it". Cancel now writes nothing — the account is left exactly as it was, old
code still valid.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

js/app.unlock.js

@@ -672,29 +672,12 @@ async function doGenerateRecoveryKey() {
     const { wrappedKey, wrappedIv } = await wrapAesKeyForRecovery(
         rawKey, code, kdfSalt);
 
-    try {
+    // Everything above is local — NOTHING is written server-side yet. The
-        // Send a verifier instead of the master pw — server proves the
+    // setup POST (which deletes any existing recovery row and inserts the new
-        // user still knows the master pw without ever seeing the plaintext.
+    // one) is deferred until AFTER the user acknowledges they saved the code.
-        const verifier = await computeVerifier(
+    // Committing before the modal meant backing out still erased the old code
-            masterPwd, state.salt, state.kdfIterations || 100000, state.hashAlgo, state.argon2Params);
+    // and activated a new one the user never saw → lockout. Cancel now leaves
-        await api('/recovery-key/setup', {
+    // the account exactly as it was.
-            method: 'POST',
-            headers: authHeaders({ 'Content-Type': 'application/json' }),
-            body: JSON.stringify({
-                verifier:   verifier,
-                codeHash:   codeHash,
-                kdfSalt:    kdfSalt,
-                wrappedKey: wrappedKey,
-                wrappedIv:  wrappedIv,
-            }),
-        });
-    } catch (err) {
-        return toast('Setup failed: ' + (err.message || ''), 'error');
-    }
-
-    // Refresh the Settings button label
-    state.recoveryConfigured = true;
-    if ($('#recoveryStatus')) updateRecoveryStatusLabel();
 
     // Show the code ONCE. Use the confirm modal so the user has to
     // explicitly click "I saved it" before the value vanishes.
@@ -727,7 +710,7 @@ async function doGenerateRecoveryKey() {
         }
     }, 0);
 
-    await confirmDialog({
+    const saved = await confirmDialog({
         title:   'Your recovery code',
         message: '<p>Save this code somewhere safe (password manager, ' +
                  'safe deposit box, printed copy). It will <b>not</b> be ' +
@@ -750,8 +733,32 @@ async function doGenerateRecoveryKey() {
                  'is permanently erased as soon as you successfully change ' +
                  'your master password — so set a new one right after ' +
                  'recovering.</p>',
-        okText: 'I saved it',
+        okText:     'I saved it',
+        cancelText: 'Cancel',
     });
+    if (!saved) return toast('Cancelled — no recovery code was set');
+
+    // Acknowledged → commit. reauthLoop already verified the master pw; the
+    // server re-checks the verifier below.
+    try {
+        const verifier = await computeVerifier(
+            masterPwd, state.salt, state.kdfIterations || 100000, state.hashAlgo, state.argon2Params);
+        await api('/recovery-key/setup', {
+            method: 'POST',
+            headers: authHeaders({ 'Content-Type': 'application/json' }),
+            body: JSON.stringify({
+                verifier:   verifier,
+                codeHash:   codeHash,
+                kdfSalt:    kdfSalt,
+                wrappedKey: wrappedKey,
+                wrappedIv:  wrappedIv,
+            }),
+        });
+    } catch (err) {
+        return toast('Setup failed: ' + (err.message || ''), 'error');
+    }
+    state.recoveryConfigured = true;
+    if ($('#recoveryStatus')) updateRecoveryStatusLabel();
     toast('Recovery code generated');
 }