diff --git a/src/handlers/ciphers.ts b/src/handlers/ciphers.ts
index 0005109..8ba428a 100644
--- a/src/handlers/ciphers.ts
+++ b/src/handlers/ciphers.ts
@@ -823,6 +823,9 @@ export async function handleUpdateCipher(request: Request, env: Env, userId: str
   const incomingPasswordHistory = readCipherProp<PasswordHistory[] | null>(cipherData, ['passwordHistory', 'PasswordHistory']);
   const incomingRevisionDate = readCipherRevisionDate(cipherData);
   const hasAttachmentMigrationMetadata = hasIncomingAttachmentMetadata(cipherData);
+  const preserveRevisionDate =
+    shouldPreserveRepairableCipherUris(request)
+    && (body.preserveRevisionDate === true || cipherData.preserveRevisionDate === true);
 
   if (incomingKey.present && !shouldAcceptCipherKey(incomingKey.value)) {
     return errorResponse('Cipher key encryption is not supported by this server. Resync the client and try again.', 400);
@@ -840,9 +843,10 @@ export async function handleUpdateCipher(request: Request, env: Env, userId: str
 
   // Opaque passthrough: merge existing stored data with ALL incoming client fields.
   // Unknown/future fields from the client are preserved; server-controlled fields are protected.
+  const { preserveRevisionDate: _preserveRevisionDate, PreserveRevisionDate: _pascalPreserveRevisionDate, ...cipherDataWithoutFlags } = cipherData;
   const cipher: Cipher = {
     ...existingCipher,   // start with all existing stored data (including unknowns)
-    ...cipherData,       // overlay all client data (including new/unknown fields)
+    ...cipherDataWithoutFlags, // overlay all client data (including new/unknown fields)
     // Server-controlled fields (never from client)
     id: existingCipher.id,
     userId: existingCipher.userId,
@@ -850,7 +854,7 @@ export async function handleUpdateCipher(request: Request, env: Env, userId: str
     favorite: cipherData.favorite ?? existingCipher.favorite,
     reprompt: cipherData.reprompt ?? existingCipher.reprompt,
     createdAt: existingCipher.createdAt,
-    updatedAt: new Date().toISOString(),
+    updatedAt: preserveRevisionDate ? existingCipher.updatedAt : new Date().toISOString(),
     archivedAt: readCipherArchivedAt(cipherData, existingCipher.archivedAt ?? null),
     deletedAt: existingCipher.deletedAt,
   };
diff --git a/webapp/src/lib/api/vault.ts b/webapp/src/lib/api/vault.ts
index 2c3638f..a531b13 100644
--- a/webapp/src/lib/api/vault.ts
+++ b/webapp/src/lib/api/vault.ts
@@ -927,6 +927,7 @@ export async function repairCipherUriChecksums(
         ? cipher.fields.map(({ decName: _decName, decValue: _decValue, ...field }) => field)
         : null,
       lastKnownRevisionDate: cipher.revisionDate ?? null,
+      preserveRevisionDate: true,
     };
     if (keys.key) payload.key = keys.key;
 
@@ -1091,7 +1092,9 @@ export async function repairCipherKeyMismatches(
     if (!cipher?.id || !looksLikeCipherString(cipher.key)) continue;
     if (!(await hasItemKeyFieldMismatch(cipher, userEnc, userMac))) continue;
     if (hasUnresolvedEncryptedFields(cipher)) continue;
-    await updateCipher(authedFetch, session, cipher, draftFromDecryptedCipher(cipher));
+    await updateCipher(authedFetch, session, cipher, draftFromDecryptedCipher(cipher), {
+      preserveRevisionDate: true,
+    });
     repaired += 1;
   }
 
@@ -1225,9 +1228,13 @@ export async function updateCipher(
   authedFetch: AuthedFetch,
   session: SessionState,
   cipher: Cipher,
-  draft: VaultDraft
+  draft: VaultDraft,
+  extraPayload?: Record<string, unknown>
 ): Promise<Cipher> {
   const payload = await buildCipherPayload(session, draft, cipher);
+  if (extraPayload) {
+    Object.assign(payload, extraPayload);
+  }
 
   const resp = await authedFetch(`/api/ciphers/${encodeURIComponent(cipher.id)}`, {
     method: 'PUT',