diff --git a/lib/tunnelbroker/peer-to-peer-context.js b/lib/tunnelbroker/peer-to-peer-context.js
index 19d8df867..40e928e48 100644
--- a/lib/tunnelbroker/peer-to-peer-context.js
+++ b/lib/tunnelbroker/peer-to-peer-context.js
@@ -1,279 +1,349 @@
 // @flow
 
 import invariant from 'invariant';
 import * as React from 'react';
 import uuid from 'uuid';
 
 import {
   type TunnelbrokerClientMessageToDevice,
   useTunnelbroker,
 } from './tunnelbroker-context.js';
 import { usePeerOlmSessionsCreatorContext } from '../components/peer-olm-session-creator-provider.react.js';
 import {
   createMessagesToPeersFromDMOp,
   type DMOperationSpecification,
 } from '../shared/dm-ops/dm-op-utils.js';
 import {
+  type AuthMetadata,
   IdentityClientContext,
   type IdentityClientContextType,
 } from '../shared/identity-client-context.js';
 import { scheduleP2PMessagesActionType } from '../types/dm-ops.js';
 import {
   type OutboundP2PMessage,
   outboundP2PMessageStatuses,
 } from '../types/sqlite-types.js';
 import {
   type EncryptedMessage,
   peerToPeerMessageTypes,
 } from '../types/tunnelbroker/peer-to-peer-message-types.js';
 import { getConfig } from '../utils/config.js';
 import { getMessageForException } from '../utils/errors.js';
 import { useDispatch, useSelector } from '../utils/redux-utils.js';
 
 type PeerToPeerContextType = {
   +processOutboundMessages: (
     outboundMessageIDs: ?$ReadOnlyArray<string>,
     dmOpID: ?string,
   ) => void,
   +sendDMOperation: (op: DMOperationSpecification) => Promise<void>,
+  +broadcastEphemeralMessage: (
+    contentPayload: string,
+    recipients: $ReadOnlyArray<{ +userID: string, +deviceID: string }>,
+    authMetadata: AuthMetadata,
+  ) => Promise<void>,
 };
 
 const PeerToPeerContext: React.Context<?PeerToPeerContextType> =
   React.createContext<?PeerToPeerContextType>();
 
 type Props = {
   +children: React.Node,
 };
 
 async function processOutboundP2PMessages(
   sendMessage: (
     message: TunnelbrokerClientMessageToDevice,
     messageID: ?string,
   ) => Promise<void>,
   identityContext: IdentityClientContextType,
   peerOlmSessionsCreator: (userID: string, deviceID: string) => Promise<void>,
   messageIDs: ?$ReadOnlyArray<string>,
 ): Promise<void> {
   const authMetadata = await identityContext.getAuthMetadata();
   if (
     !authMetadata.deviceID ||
     !authMetadata.userID ||
     !authMetadata.accessToken
   ) {
     return;
   }
 
   const { olmAPI, sqliteAPI } = getConfig();
   await olmAPI.initializeCryptoAccount();
   let messages;
   if (messageIDs) {
     messages = await sqliteAPI.getOutboundP2PMessagesByID(messageIDs);
   } else {
     const allMessages = await sqliteAPI.getAllOutboundP2PMessages();
     messages = allMessages.filter(message => message.supportsAutoRetry);
   }
 
   const devicesMap: { [deviceID: string]: OutboundP2PMessage[] } = {};
   for (const message: OutboundP2PMessage of messages) {
     if (!devicesMap[message.deviceID]) {
       devicesMap[message.deviceID] = [message];
     } else {
       devicesMap[message.deviceID].push(message);
     }
   }
 
   const sendMessageToPeer = async (
     message: OutboundP2PMessage,
   ): Promise<void> => {
     if (!authMetadata.deviceID || !authMetadata.userID) {
       return;
     }
     const encryptedMessage: EncryptedMessage = {
       type: peerToPeerMessageTypes.ENCRYPTED_MESSAGE,
       senderInfo: {
         deviceID: authMetadata.deviceID,
         userID: authMetadata.userID,
       },
       encryptedData: JSON.parse(message.ciphertext),
     };
     await sendMessage(
       {
         deviceID: message.deviceID,
         payload: JSON.stringify(encryptedMessage),
       },
       message.messageID,
     );
     await sqliteAPI.markOutboundP2PMessageAsSent(
       message.messageID,
       message.deviceID,
     );
   };
 
   for (const peerDeviceID in devicesMap) {
     for (const message of devicesMap[peerDeviceID]) {
       if (message.status === outboundP2PMessageStatuses.persisted) {
         try {
           const result = await olmAPI.encryptAndPersist(
             message.plaintext,
             message.deviceID,
             message.messageID,
           );
 
           const encryptedMessage: OutboundP2PMessage = {
             ...message,
             ciphertext: JSON.stringify(result),
           };
           await sendMessageToPeer(encryptedMessage);
         } catch (e) {
           try {
             await peerOlmSessionsCreator(message.userID, peerDeviceID);
             const result = await olmAPI.encryptAndPersist(
               message.plaintext,
               message.deviceID,
               message.messageID,
             );
             const encryptedMessage: OutboundP2PMessage = {
               ...message,
               ciphertext: JSON.stringify(result),
             };
 
             await sendMessageToPeer(encryptedMessage);
           } catch (err) {
             console.log(`Error sending messages to peer ${peerDeviceID}`, err);
             break;
           }
         }
       } else if (message.status === outboundP2PMessageStatuses.encrypted) {
         await sendMessageToPeer(message);
       }
     }
   }
 }
 
 const AUTOMATIC_RETRY_FREQUENCY = 30 * 1000;
 
 function PeerToPeerProvider(props: Props): React.Node {
   const { children } = props;
 
   const { sendMessageToDevice } = useTunnelbroker();
   const identityContext = React.useContext(IdentityClientContext);
   invariant(identityContext, 'Identity context should be set');
 
   const dispatch = useDispatch();
   const dmOpsSendingPromiseResolvers = React.useRef<
     Map<string, { +resolve: () => mixed, +reject: Error => mixed }>,
   >(new Map());
   const auxUserStore = useSelector(state => state.auxUserStore);
   const currentUserInfo = useSelector(state => state.currentUserInfo);
 
   const sendDMOperation = React.useCallback(
     async (op: DMOperationSpecification) => {
       const dmOpID = uuid.v4();
       const promise = new Promise<void>((resolve, reject) => {
         dmOpsSendingPromiseResolvers.current.set(dmOpID, { resolve, reject });
       });
 
       const messages = await createMessagesToPeersFromDMOp(
         op,
         auxUserStore,
         currentUserInfo,
       );
       dispatch({
         type: scheduleP2PMessagesActionType,
         payload: {
           dmOpID,
           messages,
         },
       });
 
       return promise;
     },
     [auxUserStore, currentUserInfo, dispatch],
   );
 
   const processingQueue = React.useRef<
     Array<{
       +outboundMessageIDs: ?$ReadOnlyArray<string>,
       +dmOpID: ?string,
     }>,
   >([]);
   const promiseRunning = React.useRef<boolean>(false);
 
   const { createOlmSessionsWithPeer: peerOlmSessionsCreator } =
     usePeerOlmSessionsCreatorContext();
 
   const processOutboundMessages = React.useCallback(
     (outboundMessageIDs: ?$ReadOnlyArray<string>, dmOpID: ?string) => {
       processingQueue.current.push({ outboundMessageIDs, dmOpID });
       if (!promiseRunning.current) {
         promiseRunning.current = true;
         void (async () => {
           do {
             const queueFront = processingQueue.current.shift();
             try {
               await processOutboundP2PMessages(
                 sendMessageToDevice,
                 identityContext,
                 peerOlmSessionsCreator,
                 queueFront?.outboundMessageIDs,
               );
               if (queueFront.dmOpID) {
                 dmOpsSendingPromiseResolvers.current
                   .get(queueFront.dmOpID)
                   ?.resolve?.();
               }
             } catch (e) {
               console.log(
                 `Error processing outbound P2P messages: ${
                   getMessageForException(e) ?? 'unknown'
                 }`,
               );
               if (queueFront.dmOpID) {
                 dmOpsSendingPromiseResolvers.current
                   .get(queueFront.dmOpID)
                   ?.reject?.(e);
               }
             } finally {
               if (queueFront.dmOpID) {
                 dmOpsSendingPromiseResolvers.current.delete(queueFront.dmOpID);
               }
             }
           } while (processingQueue.current.length > 0);
           promiseRunning.current = false;
         })();
       }
     },
     [peerOlmSessionsCreator, identityContext, sendMessageToDevice],
   );
 
+  const broadcastEphemeralMessage = React.useCallback(
+    async (
+      contentPayload: string,
+      recipients: $ReadOnlyArray<{ +userID: string, +deviceID: string }>,
+      authMetadata: AuthMetadata,
+    ) => {
+      const { userID: thisUserID, deviceID: thisDeviceID } = authMetadata;
+      if (!thisDeviceID || !thisUserID) {
+        throw new Error('No auth metadata');
+      }
+      const { olmAPI } = getConfig();
+      await olmAPI.initializeCryptoAccount();
+
+      // We want it distinct by device ID to avoid potentially creating
+      // multiple Olm sessions with the same device simultaneously.
+      const recipientsDistinctByDeviceID = [
+        ...new Map(recipients.map(item => [item.deviceID, item])).values(),
+      ];
+      const senderInfo = { deviceID: thisDeviceID, userID: thisUserID };
+      const promises = recipientsDistinctByDeviceID.map(async recipient => {
+        try {
+          const encryptedData = await olmAPI.encrypt(
+            contentPayload,
+            recipient.deviceID,
+          );
+          const encryptedMessage: EncryptedMessage = {
+            type: peerToPeerMessageTypes.ENCRYPTED_MESSAGE,
+            senderInfo,
+            encryptedData,
+          };
+          await sendMessageToDevice({
+            deviceID: recipient.deviceID,
+            payload: JSON.stringify(encryptedMessage),
+          });
+        } catch {
+          try {
+            await peerOlmSessionsCreator(recipient.userID, recipient.deviceID);
+            const encryptedData = await olmAPI.encrypt(
+              contentPayload,
+              recipient.deviceID,
+            );
+            const encryptedMessage: EncryptedMessage = {
+              type: peerToPeerMessageTypes.ENCRYPTED_MESSAGE,
+              senderInfo,
+              encryptedData,
+            };
+            await sendMessageToDevice({
+              deviceID: recipient.deviceID,
+              payload: JSON.stringify(encryptedMessage),
+            });
+          } catch (err) {
+            console.warn(
+              `Error sending Olm-encrypted message to device ${recipient.deviceID}:`,
+              err,
+            );
+          }
+        }
+      });
+      await Promise.all(promises);
+    },
+    [peerOlmSessionsCreator, sendMessageToDevice],
+  );
+
   React.useEffect(() => {
     const intervalID = setInterval(
       processOutboundMessages,
       AUTOMATIC_RETRY_FREQUENCY,
     );
     return () => clearInterval(intervalID);
   }, [processOutboundMessages]);
 
   const value: PeerToPeerContextType = React.useMemo(
     () => ({
       processOutboundMessages,
       sendDMOperation,
+      broadcastEphemeralMessage,
     }),
-    [processOutboundMessages, sendDMOperation],
+    [broadcastEphemeralMessage, processOutboundMessages, sendDMOperation],
   );
 
   return (
     <PeerToPeerContext.Provider value={value}>
       {children}
     </PeerToPeerContext.Provider>
   );
 }
 
 function usePeerToPeerCommunication(): PeerToPeerContextType {
   const context = React.useContext(PeerToPeerContext);
   invariant(context, 'PeerToPeerContext not found');
 
   return context;
 }
 
 export { PeerToPeerProvider, usePeerToPeerCommunication };