diff --git a/web/input/input-state-container.react.js b/web/input/input-state-container.react.js
index 00b7c3d37..34fd31424 100644
--- a/web/input/input-state-container.react.js
+++ b/web/input/input-state-container.react.js
@@ -1,1273 +1,1298 @@
 // @flow
 
 import { detect as detectBrowser } from 'detect-browser';
 import invariant from 'invariant';
 import _groupBy from 'lodash/fp/groupBy';
 import _keyBy from 'lodash/fp/keyBy';
 import _omit from 'lodash/fp/omit';
 import _partition from 'lodash/fp/partition';
 import _sortBy from 'lodash/fp/sortBy';
 import _memoize from 'lodash/memoize';
 import * as React from 'react';
 import { useDispatch } from 'react-redux';
 import { createSelector } from 'reselect';
 
 import {
   createLocalMessageActionType,
   sendMultimediaMessageActionTypes,
   sendMultimediaMessage,
   sendTextMessageActionTypes,
   sendTextMessage,
 } from 'lib/actions/message-actions';
 import { queueReportsActionType } from 'lib/actions/report-actions';
 import { newThread } from 'lib/actions/thread-actions';
 import {
   uploadMultimedia,
   updateMultimediaMessageMediaActionType,
   deleteUpload,
   type MultimediaUploadCallbacks,
   type MultimediaUploadExtras,
 } from 'lib/actions/upload-actions';
 import { getNextLocalUploadID } from 'lib/media/media-utils';
 import { locallyUniqueToRealizedThreadIDsSelector } from 'lib/selectors/thread-selectors';
 import {
   createMediaMessageInfo,
   localIDPrefix,
 } from 'lib/shared/message-utils';
 import {
   createRealThreadFromPendingThread,
   threadIsPending,
 } from 'lib/shared/thread-utils';
 import type { CalendarQuery } from 'lib/types/entry-types';
 import type {
   UploadMultimediaResult,
   MediaMissionStep,
   MediaMissionFailure,
   MediaMissionResult,
   MediaMission,
 } from 'lib/types/media-types';
 import {
   messageTypes,
   type RawMessageInfo,
   type RawMultimediaMessageInfo,
   type SendMessageResult,
   type SendMessagePayload,
 } from 'lib/types/message-types';
 import type { RawImagesMessageInfo } from 'lib/types/messages/images';
 import type { RawMediaMessageInfo } from 'lib/types/messages/media';
 import type { RawTextMessageInfo } from 'lib/types/messages/text';
 import type { Dispatch } from 'lib/types/redux-types';
 import { reportTypes } from 'lib/types/report-types';
 import type {
   ClientNewThreadRequest,
   NewThreadResult,
   ThreadInfo,
 } from 'lib/types/thread-types';
 import {
   type DispatchActionPromise,
   useServerCall,
   useDispatchActionPromise,
 } from 'lib/utils/action-utils';
 import { getConfig } from 'lib/utils/config';
 import { getMessageForException, cloneError } from 'lib/utils/errors';
 
 import { validateFile, preloadImage } from '../media/media-utils';
 import InvalidUploadModal from '../modals/chat/invalid-upload.react';
 import { useModalContext } from '../modals/modal-provider.react';
 import { useSelector } from '../redux/redux-utils';
 import { nonThreadCalendarQuery } from '../selectors/nav-selectors';
 import { type PendingMultimediaUpload, InputStateContext } from './input-state';
 
 type BaseProps = {
   +children: React.Node,
 };
 type Props = {
   ...BaseProps,
   +activeChatThreadID: ?string,
   +viewerID: ?string,
   +messageStoreMessages: { +[id: string]: RawMessageInfo },
   +exifRotate: boolean,
   +locallyUniqueRealizedThreadIDs: $ReadOnlyMap<string, string>,
   +dispatch: Dispatch,
   +dispatchActionPromise: DispatchActionPromise,
   +calendarQuery: () => CalendarQuery,
   +uploadMultimedia: (
     multimedia: Object,
     extras: MultimediaUploadExtras,
     callbacks: MultimediaUploadCallbacks,
   ) => Promise<UploadMultimediaResult>,
   +deleteUpload: (id: string) => Promise<void>,
   +sendMultimediaMessage: (
     threadID: string,
     localID: string,
     mediaIDs: $ReadOnlyArray<string>,
   ) => Promise<SendMessageResult>,
   +sendTextMessage: (
     threadID: string,
     localID: string,
     text: string,
   ) => Promise<SendMessageResult>,
   +newThread: (request: ClientNewThreadRequest) => Promise<NewThreadResult>,
   +pushModal: (modal: React.Node) => void,
+  +sendCallbacks: $ReadOnlyArray<() => mixed>,
+  +registerSendCallback: (() => mixed) => void,
+  +unregisterSendCallback: (() => mixed) => void,
 };
 type State = {
   +pendingUploads: {
     [threadID: string]: { [localUploadID: string]: PendingMultimediaUpload },
   },
   +drafts: { [threadID: string]: string },
 };
 class InputStateContainer extends React.PureComponent<Props, State> {
   state: State = {
     pendingUploads: {},
     drafts: {},
   };
   replyCallbacks: Array<(message: string) => void> = [];
   pendingThreadCreations = new Map<string, Promise<string>>();
 
   static reassignToRealizedThreads<T>(
     state: { +[threadID: string]: T },
     props: Props,
   ): ?{ [threadID: string]: T } {
     const newState = {};
     let updated = false;
     for (const threadID in state) {
       const newThreadID =
         props.locallyUniqueRealizedThreadIDs.get(threadID) ?? threadID;
       if (newThreadID !== threadID) {
         updated = true;
       }
       newState[newThreadID] = state[threadID];
     }
     return updated ? newState : null;
   }
 
   static getDerivedStateFromProps(props: Props, state: State) {
     const drafts = InputStateContainer.reassignToRealizedThreads(
       state.drafts,
       props,
     );
     const pendingUploads = InputStateContainer.reassignToRealizedThreads(
       state.pendingUploads,
       props,
     );
 
     if (!drafts && !pendingUploads) {
       return null;
     }
 
     const stateUpdate = {};
     if (drafts) {
       stateUpdate.drafts = drafts;
     }
     if (pendingUploads) {
       stateUpdate.pendingUploads = pendingUploads;
     }
     return stateUpdate;
   }
 
   static completedMessageIDs(state: State) {
     const completed = new Map();
     for (const threadID in state.pendingUploads) {
       const pendingUploads = state.pendingUploads[threadID];
       for (const localUploadID in pendingUploads) {
         const upload = pendingUploads[localUploadID];
         const { messageID, serverID, failed } = upload;
         if (!messageID || !messageID.startsWith(localIDPrefix)) {
           continue;
         }
         if (!serverID || failed) {
           completed.set(messageID, false);
           continue;
         }
         if (completed.get(messageID) === undefined) {
           completed.set(messageID, true);
         }
       }
     }
     const messageIDs = new Set();
     for (const [messageID, isCompleted] of completed) {
       if (isCompleted) {
         messageIDs.add(messageID);
       }
     }
     return messageIDs;
   }
 
   componentDidUpdate(prevProps: Props, prevState: State) {
     if (this.props.viewerID !== prevProps.viewerID) {
       this.setState({ pendingUploads: {} });
       return;
     }
 
     const previouslyAssignedMessageIDs = new Set();
     for (const threadID in prevState.pendingUploads) {
       const pendingUploads = prevState.pendingUploads[threadID];
       for (const localUploadID in pendingUploads) {
         const { messageID } = pendingUploads[localUploadID];
         if (messageID) {
           previouslyAssignedMessageIDs.add(messageID);
         }
       }
     }
 
     const newlyAssignedUploads = new Map();
     for (const threadID in this.state.pendingUploads) {
       const pendingUploads = this.state.pendingUploads[threadID];
       for (const localUploadID in pendingUploads) {
         const upload = pendingUploads[localUploadID];
         const { messageID } = upload;
         if (
           !messageID ||
           !messageID.startsWith(localIDPrefix) ||
           previouslyAssignedMessageIDs.has(messageID)
         ) {
           continue;
         }
         let assignedUploads = newlyAssignedUploads.get(messageID);
         if (!assignedUploads) {
           assignedUploads = { threadID, uploads: [] };
           newlyAssignedUploads.set(messageID, assignedUploads);
         }
         assignedUploads.uploads.push(upload);
       }
     }
 
     const newMessageInfos = new Map();
     for (const [messageID, assignedUploads] of newlyAssignedUploads) {
       const { uploads, threadID } = assignedUploads;
       const creatorID = this.props.viewerID;
       invariant(creatorID, 'need viewer ID in order to send a message');
       const media = uploads.map(
         ({ localID, serverID, uri, mediaType, dimensions }) => {
           // We can get into this state where dimensions are null if the user is
           // uploading a file type that the browser can't render. In that case
           // we fake the dimensions here while we wait for the server to tell us
           // the true dimensions. We actually don't use the dimensions on the
           // web side currently, but if we ever change that (for instance if we
           // want to render a properly sized loading overlay like we do on
           // native), 0,0 is probably a good default.
           const shimmedDimensions = dimensions
             ? dimensions
             : { height: 0, width: 0 };
           invariant(
             mediaType === 'photo',
             "web InputStateContainer can't handle video",
           );
           return {
             id: serverID ? serverID : localID,
             uri,
             type: 'photo',
             dimensions: shimmedDimensions,
           };
         },
       );
       const messageInfo = createMediaMessageInfo({
         localID: messageID,
         threadID,
         creatorID,
         media,
       });
       newMessageInfos.set(messageID, messageInfo);
     }
 
     const currentlyCompleted = InputStateContainer.completedMessageIDs(
       this.state,
     );
     const previouslyCompleted = InputStateContainer.completedMessageIDs(
       prevState,
     );
     for (const messageID of currentlyCompleted) {
       if (previouslyCompleted.has(messageID)) {
         continue;
       }
       let rawMessageInfo = newMessageInfos.get(messageID);
       if (rawMessageInfo) {
         newMessageInfos.delete(messageID);
       } else {
         rawMessageInfo = this.getRawMultimediaMessageInfo(messageID);
       }
       this.sendMultimediaMessage(rawMessageInfo);
     }
 
     for (const [, messageInfo] of newMessageInfos) {
       this.props.dispatch({
         type: createLocalMessageActionType,
         payload: messageInfo,
       });
     }
   }
 
   getRawMultimediaMessageInfo(
     localMessageID: string,
   ): RawMultimediaMessageInfo {
     const rawMessageInfo = this.props.messageStoreMessages[localMessageID];
     invariant(rawMessageInfo, `rawMessageInfo ${localMessageID} should exist`);
     invariant(
       rawMessageInfo.type === messageTypes.IMAGES ||
         rawMessageInfo.type === messageTypes.MULTIMEDIA,
       `rawMessageInfo ${localMessageID} should be multimedia`,
     );
     return rawMessageInfo;
   }
 
   async sendMultimediaMessage(messageInfo: RawMultimediaMessageInfo) {
     if (!threadIsPending(messageInfo.threadID)) {
       this.props.dispatchActionPromise(
         sendMultimediaMessageActionTypes,
         this.sendMultimediaMessageAction(messageInfo),
         undefined,
         messageInfo,
       );
       return;
     }
 
     this.props.dispatch({
       type: sendMultimediaMessageActionTypes.started,
       payload: messageInfo,
     });
 
     let newThreadID = null;
     try {
       const threadCreationPromise = this.pendingThreadCreations.get(
         messageInfo.threadID,
       );
       if (!threadCreationPromise) {
         // When we create or retry multimedia message, we add a promise to
         // pendingThreadCreations map. This promise can be removed in
         // sendMultimediaMessage and sendTextMessage methods. When any of these
         // method remove the promise, it has to be settled. If the promise was
         // fulfilled, this method would be called with realized thread, so we
         // can conclude that the promise was rejected. We don't have enough info
         // here to retry the thread creation, but we can mark the message as
         // failed. Then the retry will be possible and promise will be created
         // again.
         throw new Error('Thread creation failed');
       }
       newThreadID = await threadCreationPromise;
     } catch (e) {
       const copy = cloneError(e);
       copy.localID = messageInfo.localID;
       copy.threadID = messageInfo.threadID;
       this.props.dispatch({
         type: sendMultimediaMessageActionTypes.failed,
         payload: copy,
         error: true,
       });
       return;
     } finally {
       this.pendingThreadCreations.delete(messageInfo.threadID);
     }
 
     const newMessageInfo = {
       ...messageInfo,
       threadID: newThreadID,
       time: Date.now(),
     };
     this.props.dispatchActionPromise(
       sendMultimediaMessageActionTypes,
       this.sendMultimediaMessageAction(newMessageInfo),
       undefined,
       newMessageInfo,
     );
   }
 
   async sendMultimediaMessageAction(
     messageInfo: RawMultimediaMessageInfo,
   ): Promise<SendMessagePayload> {
     const { localID, threadID } = messageInfo;
     invariant(
       localID !== null && localID !== undefined,
       'localID should be set',
     );
     const mediaIDs = [];
     for (const { id } of messageInfo.media) {
       mediaIDs.push(id);
     }
     try {
       const result = await this.props.sendMultimediaMessage(
         threadID,
         localID,
         mediaIDs,
       );
       this.setState(prevState => {
         const newThreadID = this.getRealizedOrPendingThreadID(threadID);
         const prevUploads = prevState.pendingUploads[newThreadID];
         const newUploads = {};
         for (const localUploadID in prevUploads) {
           const upload = prevUploads[localUploadID];
           if (upload.messageID !== localID) {
             newUploads[localUploadID] = upload;
           } else if (!upload.uriIsReal) {
             newUploads[localUploadID] = {
               ...upload,
               messageID: result.id,
             };
           }
         }
         return {
           pendingUploads: {
             ...prevState.pendingUploads,
             [newThreadID]: newUploads,
           },
         };
       });
       return {
         localID,
         serverID: result.id,
         threadID,
         time: result.time,
         interface: result.interface,
       };
     } catch (e) {
       const copy = cloneError(e);
       copy.localID = localID;
       copy.threadID = threadID;
       throw copy;
     }
   }
 
   async startThreadCreation(threadInfo: ThreadInfo): Promise<string> {
     if (!threadIsPending(threadInfo.id)) {
       return threadInfo.id;
     }
     let threadCreationPromise = this.pendingThreadCreations.get(threadInfo.id);
     if (!threadCreationPromise) {
       const calendarQuery = this.props.calendarQuery();
       threadCreationPromise = createRealThreadFromPendingThread({
         threadInfo,
         dispatchActionPromise: this.props.dispatchActionPromise,
         createNewThread: this.props.newThread,
         sourceMessageID: threadInfo.sourceMessageID,
         viewerID: this.props.viewerID,
         calendarQuery,
       });
       this.pendingThreadCreations.set(threadInfo.id, threadCreationPromise);
     }
     return threadCreationPromise;
   }
 
   inputStateSelector = _memoize((threadID: string) =>
     createSelector(
       (state: State) => state.pendingUploads[threadID],
       (state: State) => state.drafts[threadID],
       (
         pendingUploads: ?{ [localUploadID: string]: PendingMultimediaUpload },
         draft: ?string,
       ) => {
         let threadPendingUploads = [];
         const assignedUploads = {};
         if (pendingUploads) {
           const [uploadsWithMessageIDs, uploadsWithoutMessageIDs] = _partition(
             'messageID',
           )(pendingUploads);
           threadPendingUploads = _sortBy('localID')(uploadsWithoutMessageIDs);
           const threadAssignedUploads = _groupBy('messageID')(
             uploadsWithMessageIDs,
           );
           for (const messageID in threadAssignedUploads) {
             // lodash libdefs don't return $ReadOnlyArray
             assignedUploads[messageID] = [...threadAssignedUploads[messageID]];
           }
         }
         return {
           pendingUploads: threadPendingUploads,
           assignedUploads,
           draft: draft ? draft : '',
           appendFiles: (files: $ReadOnlyArray<File>) =>
             this.appendFiles(threadID, files),
           cancelPendingUpload: (localUploadID: string) =>
             this.cancelPendingUpload(threadID, localUploadID),
           sendTextMessage: (
             messageInfo: RawTextMessageInfo,
             threadInfo: ThreadInfo,
           ) => this.sendTextMessage(messageInfo, threadInfo),
           createMultimediaMessage: (localID: number, threadInfo: ThreadInfo) =>
             this.createMultimediaMessage(localID, threadInfo),
           setDraft: (newDraft: string) => this.setDraft(threadID, newDraft),
           messageHasUploadFailure: (localMessageID: string) =>
             this.messageHasUploadFailure(assignedUploads[localMessageID]),
           retryMultimediaMessage: (
             localMessageID: string,
             threadInfo: ThreadInfo,
           ) =>
             this.retryMultimediaMessage(
               localMessageID,
               threadInfo,
               assignedUploads[localMessageID],
             ),
           addReply: (message: string) => this.addReply(message),
           addReplyListener: this.addReplyListener,
           removeReplyListener: this.removeReplyListener,
+          registerSendCallback: this.props.registerSendCallback,
+          unregisterSendCallback: this.props.unregisterSendCallback,
         };
       },
     ),
   );
 
   getRealizedOrPendingThreadID(threadID: string): string {
     return this.props.locallyUniqueRealizedThreadIDs.get(threadID) ?? threadID;
   }
 
   async appendFiles(
     threadID: string,
     files: $ReadOnlyArray<File>,
   ): Promise<boolean> {
     const selectionTime = Date.now();
     const { pushModal } = this.props;
 
     const appendResults = await Promise.all(
       files.map(file => this.appendFile(file, selectionTime)),
     );
 
     if (appendResults.some(({ result }) => !result.success)) {
       pushModal(<InvalidUploadModal />);
 
       const time = Date.now() - selectionTime;
       const reports = [];
       for (const appendResult of appendResults) {
         const { steps } = appendResult;
         let { result } = appendResult;
         let uploadLocalID;
         if (result.success) {
           uploadLocalID = result.pendingUpload.localID;
           result = { success: false, reason: 'web_sibling_validation_failed' };
         }
         const mediaMission = { steps, result, userTime: time, totalTime: time };
         reports.push({ mediaMission, uploadLocalID });
       }
       this.queueMediaMissionReports(reports);
 
       return false;
     }
 
     const newUploads = appendResults.map(({ result }) => {
       invariant(result.success, 'any failed validation should be caught above');
       return result.pendingUpload;
     });
 
     const newUploadsObject = _keyBy('localID')(newUploads);
     this.setState(
       prevState => {
         const newThreadID = this.getRealizedOrPendingThreadID(threadID);
         const prevUploads = prevState.pendingUploads[newThreadID];
         const mergedUploads = prevUploads
           ? { ...prevUploads, ...newUploadsObject }
           : newUploadsObject;
         return {
           pendingUploads: {
             ...prevState.pendingUploads,
             [newThreadID]: mergedUploads,
           },
         };
       },
       () => this.uploadFiles(threadID, newUploads),
     );
     return true;
   }
 
   async appendFile(
     file: File,
     selectTime: number,
   ): Promise<{
     steps: $ReadOnlyArray<MediaMissionStep>,
     result:
       | MediaMissionFailure
       | { success: true, pendingUpload: PendingMultimediaUpload },
   }> {
     const steps = [
       {
         step: 'web_selection',
         filename: file.name,
         size: file.size,
         mime: file.type,
         selectTime,
       },
     ];
 
     let response;
     const validationStart = Date.now();
     try {
       response = await validateFile(file, this.props.exifRotate);
     } catch (e) {
       return {
         steps,
         result: {
           success: false,
           reason: 'processing_exception',
           time: Date.now() - validationStart,
           exceptionMessage: getMessageForException(e),
         },
       };
     }
     const { steps: validationSteps, result } = response;
     steps.push(...validationSteps);
     if (!result.success) {
       return { steps, result };
     }
 
     const { uri, file: fixedFile, mediaType, dimensions } = result;
     return {
       steps,
       result: {
         success: true,
         pendingUpload: {
           localID: getNextLocalUploadID(),
           serverID: null,
           messageID: null,
           failed: null,
           file: fixedFile,
           mediaType,
           dimensions,
           uri,
           loop: false,
           uriIsReal: false,
           progressPercent: 0,
           abort: null,
           steps,
           selectTime,
         },
       },
     };
   }
 
   uploadFiles(
     threadID: string,
     uploads: $ReadOnlyArray<PendingMultimediaUpload>,
   ) {
     return Promise.all(
       uploads.map(upload => this.uploadFile(threadID, upload)),
     );
   }
 
   async uploadFile(threadID: string, upload: PendingMultimediaUpload) {
     const { selectTime, localID } = upload;
     const steps = [...upload.steps];
     let userTime;
 
     const sendReport = (missionResult: MediaMissionResult) => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadID);
       const latestUpload = this.state.pendingUploads[newThreadID][localID];
       invariant(
         latestUpload,
         `pendingUpload ${localID} for ${newThreadID} missing in sendReport`,
       );
       const { serverID, messageID } = latestUpload;
       const totalTime = Date.now() - selectTime;
       userTime = userTime ? userTime : totalTime;
       const mission = { steps, result: missionResult, totalTime, userTime };
       this.queueMediaMissionReports([
         {
           mediaMission: mission,
           uploadLocalID: localID,
           uploadServerID: serverID,
           messageLocalID: messageID,
         },
       ]);
     };
 
     let uploadResult, uploadExceptionMessage;
     const uploadStart = Date.now();
     try {
       uploadResult = await this.props.uploadMultimedia(
         upload.file,
         { ...upload.dimensions, loop: false },
         {
           onProgress: (percent: number) =>
             this.setProgress(threadID, localID, percent),
           abortHandler: (abort: () => void) =>
             this.handleAbortCallback(threadID, localID, abort),
         },
       );
     } catch (e) {
       uploadExceptionMessage = getMessageForException(e);
       this.handleUploadFailure(threadID, localID, e);
     }
     userTime = Date.now() - selectTime;
     steps.push({
       step: 'upload',
       success: !!uploadResult,
       exceptionMessage: uploadExceptionMessage,
       time: Date.now() - uploadStart,
       inputFilename: upload.file.name,
       outputMediaType: uploadResult && uploadResult.mediaType,
       outputURI: uploadResult && uploadResult.uri,
       outputDimensions: uploadResult && uploadResult.dimensions,
       outputLoop: uploadResult && uploadResult.loop,
     });
     if (!uploadResult) {
       sendReport({
         success: false,
         reason: 'http_upload_failed',
         exceptionMessage: uploadExceptionMessage,
       });
       return;
     }
     const result = uploadResult;
 
     const successThreadID = this.getRealizedOrPendingThreadID(threadID);
     const uploadAfterSuccess = this.state.pendingUploads[successThreadID][
       localID
     ];
     invariant(
       uploadAfterSuccess,
       `pendingUpload ${localID}/${result.id} for ${successThreadID} missing ` +
         `after upload`,
     );
     if (uploadAfterSuccess.messageID) {
       this.props.dispatch({
         type: updateMultimediaMessageMediaActionType,
         payload: {
           messageID: uploadAfterSuccess.messageID,
           currentMediaID: localID,
           mediaUpdate: {
             id: result.id,
           },
         },
       });
     }
 
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadID);
       const uploads = prevState.pendingUploads[newThreadID];
       const currentUpload = uploads[localID];
       invariant(
         currentUpload,
         `pendingUpload ${localID}/${result.id} for ${newThreadID} ` +
           `missing while assigning serverID`,
       );
       return {
         pendingUploads: {
           ...prevState.pendingUploads,
           [newThreadID]: {
             ...uploads,
             [localID]: {
               ...currentUpload,
               serverID: result.id,
               abort: null,
             },
           },
         },
       };
     });
 
     const { steps: preloadSteps } = await preloadImage(result.uri);
     steps.push(...preloadSteps);
     sendReport({ success: true });
 
     const preloadThreadID = this.getRealizedOrPendingThreadID(threadID);
     const uploadAfterPreload = this.state.pendingUploads[preloadThreadID][
       localID
     ];
     invariant(
       uploadAfterPreload,
       `pendingUpload ${localID}/${result.id} for ${preloadThreadID} missing ` +
         `after preload`,
     );
     if (uploadAfterPreload.messageID) {
       const { mediaType, uri, dimensions, loop } = result;
       this.props.dispatch({
         type: updateMultimediaMessageMediaActionType,
         payload: {
           messageID: uploadAfterPreload.messageID,
           currentMediaID: uploadAfterPreload.serverID
             ? uploadAfterPreload.serverID
             : uploadAfterPreload.localID,
           mediaUpdate: { type: mediaType, uri, dimensions, loop },
         },
       });
     }
 
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadID);
       const uploads = prevState.pendingUploads[newThreadID];
       const currentUpload = uploads[localID];
       invariant(
         currentUpload,
         `pendingUpload ${localID}/${result.id} for ${newThreadID} ` +
           `missing while assigning URI`,
       );
       const { messageID } = currentUpload;
       if (messageID && !messageID.startsWith(localIDPrefix)) {
         const newPendingUploads = _omit([localID])(uploads);
         return {
           pendingUploads: {
             ...prevState.pendingUploads,
             [newThreadID]: newPendingUploads,
           },
         };
       }
       return {
         pendingUploads: {
           ...prevState.pendingUploads,
           [newThreadID]: {
             ...uploads,
             [localID]: {
               ...currentUpload,
               uri: result.uri,
               mediaType: result.mediaType,
               dimensions: result.dimensions,
               uriIsReal: true,
               loop: result.loop,
             },
           },
         },
       };
     });
   }
 
   handleAbortCallback(
     threadID: string,
     localUploadID: string,
     abort: () => void,
   ) {
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadID);
       const uploads = prevState.pendingUploads[newThreadID];
       const upload = uploads[localUploadID];
       if (!upload) {
         // The upload has been cancelled before we were even handed the
         // abort function. We should immediately abort.
         abort();
       }
       return {
         pendingUploads: {
           ...prevState.pendingUploads,
           [newThreadID]: {
             ...uploads,
             [localUploadID]: {
               ...upload,
               abort,
             },
           },
         },
       };
     });
   }
 
   handleUploadFailure(threadID: string, localUploadID: string, e: any) {
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadID);
       const uploads = prevState.pendingUploads[newThreadID];
       const upload = uploads[localUploadID];
       if (!upload || !upload.abort || upload.serverID) {
         // The upload has been cancelled or completed before it failed
         return {};
       }
       const failed = e instanceof Error && e.message ? e.message : 'failed';
       return {
         pendingUploads: {
           ...prevState.pendingUploads,
           [newThreadID]: {
             ...uploads,
             [localUploadID]: {
               ...upload,
               failed,
               progressPercent: 0,
               abort: null,
             },
           },
         },
       };
     });
   }
 
   queueMediaMissionReports(
     partials: $ReadOnlyArray<{
       mediaMission: MediaMission,
       uploadLocalID?: ?string,
       uploadServerID?: ?string,
       messageLocalID?: ?string,
     }>,
   ) {
     const reports = partials.map(
       ({ mediaMission, uploadLocalID, uploadServerID, messageLocalID }) => ({
         type: reportTypes.MEDIA_MISSION,
         time: Date.now(),
         platformDetails: getConfig().platformDetails,
         mediaMission,
         uploadServerID,
         uploadLocalID,
         messageLocalID,
       }),
     );
     this.props.dispatch({ type: queueReportsActionType, payload: { reports } });
   }
 
   cancelPendingUpload(threadID: string, localUploadID: string) {
     let revokeURL, abortRequest;
     this.setState(
       prevState => {
         const newThreadID = this.getRealizedOrPendingThreadID(threadID);
         const currentPendingUploads = prevState.pendingUploads[newThreadID];
         if (!currentPendingUploads) {
           return {};
         }
         const pendingUpload = currentPendingUploads[localUploadID];
         if (!pendingUpload) {
           return {};
         }
         if (!pendingUpload.uriIsReal) {
           revokeURL = pendingUpload.uri;
         }
         if (pendingUpload.abort) {
           abortRequest = pendingUpload.abort;
         }
         if (pendingUpload.serverID) {
           this.props.deleteUpload(pendingUpload.serverID);
         }
         const newPendingUploads = _omit([localUploadID])(currentPendingUploads);
         return {
           pendingUploads: {
             ...prevState.pendingUploads,
             [newThreadID]: newPendingUploads,
           },
         };
       },
       () => {
         if (revokeURL) {
           URL.revokeObjectURL(revokeURL);
         }
         if (abortRequest) {
           abortRequest();
         }
       },
     );
   }
 
   async sendTextMessage(
     messageInfo: RawTextMessageInfo,
     threadInfo: ThreadInfo,
   ) {
+    this.props.sendCallbacks.forEach(callback => callback());
+
     if (!threadIsPending(threadInfo.id)) {
       this.props.dispatchActionPromise(
         sendTextMessageActionTypes,
         this.sendTextMessageAction(messageInfo),
         undefined,
         messageInfo,
       );
       return;
     }
 
     this.props.dispatch({
       type: sendTextMessageActionTypes.started,
       payload: messageInfo,
     });
 
     let newThreadID = null;
     try {
       newThreadID = await this.startThreadCreation(threadInfo);
     } catch (e) {
       const copy = cloneError(e);
       copy.localID = messageInfo.localID;
       copy.threadID = messageInfo.threadID;
       this.props.dispatch({
         type: sendTextMessageActionTypes.failed,
         payload: copy,
         error: true,
       });
       return;
     } finally {
       this.pendingThreadCreations.delete(threadInfo.id);
     }
 
     const newMessageInfo = {
       ...messageInfo,
       threadID: newThreadID,
       time: Date.now(),
     };
     this.props.dispatchActionPromise(
       sendTextMessageActionTypes,
       this.sendTextMessageAction(newMessageInfo),
       undefined,
       newMessageInfo,
     );
   }
 
   async sendTextMessageAction(
     messageInfo: RawTextMessageInfo,
   ): Promise<SendMessagePayload> {
     try {
       const { localID } = messageInfo;
       invariant(
         localID !== null && localID !== undefined,
         'localID should be set',
       );
       const result = await this.props.sendTextMessage(
         messageInfo.threadID,
         localID,
         messageInfo.text,
       );
       return {
         localID,
         serverID: result.id,
         threadID: messageInfo.threadID,
         time: result.time,
         interface: result.interface,
       };
     } catch (e) {
       const copy = cloneError(e);
       copy.localID = messageInfo.localID;
       copy.threadID = messageInfo.threadID;
       throw copy;
     }
   }
 
   // Creates a MultimediaMessage from the unassigned pending uploads,
   // if there are any
   createMultimediaMessage(localID: number, threadInfo: ThreadInfo) {
     const localMessageID = `${localIDPrefix}${localID}`;
     this.startThreadCreation(threadInfo);
 
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadInfo.id);
       const currentPendingUploads = prevState.pendingUploads[newThreadID];
       if (!currentPendingUploads) {
         return {};
       }
       const newPendingUploads = {};
       let uploadAssigned = false;
       for (const localUploadID in currentPendingUploads) {
         const upload = currentPendingUploads[localUploadID];
         if (upload.messageID) {
           newPendingUploads[localUploadID] = upload;
         } else {
           const newUpload = {
             ...upload,
             messageID: localMessageID,
           };
           uploadAssigned = true;
           newPendingUploads[localUploadID] = newUpload;
         }
       }
       if (!uploadAssigned) {
         return {};
       }
       return {
         pendingUploads: {
           ...prevState.pendingUploads,
           [newThreadID]: newPendingUploads,
         },
       };
     });
   }
 
   setDraft(threadID: string, draft: string) {
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadID);
       return {
         drafts: {
           ...prevState.drafts,
           [newThreadID]: draft,
         },
       };
     });
   }
 
   setProgress(
     threadID: string,
     localUploadID: string,
     progressPercent: number,
   ) {
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadID);
       const pendingUploads = prevState.pendingUploads[newThreadID];
       if (!pendingUploads) {
         return {};
       }
       const pendingUpload = pendingUploads[localUploadID];
       if (!pendingUpload) {
         return {};
       }
       const newPendingUploads = {
         ...pendingUploads,
         [localUploadID]: {
           ...pendingUpload,
           progressPercent,
         },
       };
       return {
         pendingUploads: {
           ...prevState.pendingUploads,
           [newThreadID]: newPendingUploads,
         },
       };
     });
   }
 
   messageHasUploadFailure(
     pendingUploads: ?$ReadOnlyArray<PendingMultimediaUpload>,
   ) {
     if (!pendingUploads) {
       return false;
     }
     return pendingUploads.some(upload => upload.failed);
   }
 
   retryMultimediaMessage(
     localMessageID: string,
     threadInfo: ThreadInfo,
     pendingUploads: ?$ReadOnlyArray<PendingMultimediaUpload>,
   ) {
     const rawMessageInfo = this.getRawMultimediaMessageInfo(localMessageID);
     let newRawMessageInfo;
     // This conditional is for Flow
     if (rawMessageInfo.type === messageTypes.MULTIMEDIA) {
       newRawMessageInfo = ({
         ...rawMessageInfo,
         time: Date.now(),
       }: RawMediaMessageInfo);
     } else {
       newRawMessageInfo = ({
         ...rawMessageInfo,
         time: Date.now(),
       }: RawImagesMessageInfo);
     }
 
     this.startThreadCreation(threadInfo);
 
     const completed = InputStateContainer.completedMessageIDs(this.state);
     if (completed.has(localMessageID)) {
       this.sendMultimediaMessage(newRawMessageInfo);
       return;
     }
 
     if (!pendingUploads) {
       return;
     }
 
     // We're not actually starting the send here,
     // we just use this action to update the message's timestamp in Redux
     this.props.dispatch({
       type: sendMultimediaMessageActionTypes.started,
       payload: newRawMessageInfo,
     });
 
     const uploadIDsToRetry = new Set();
     const uploadsToRetry = [];
     for (const pendingUpload of pendingUploads) {
       const { serverID, messageID, localID, abort } = pendingUpload;
       if (serverID || messageID !== localMessageID) {
         continue;
       }
       if (abort) {
         abort();
       }
       uploadIDsToRetry.add(localID);
       uploadsToRetry.push(pendingUpload);
     }
 
     this.setState(prevState => {
       const newThreadID = this.getRealizedOrPendingThreadID(threadInfo.id);
       const prevPendingUploads = prevState.pendingUploads[newThreadID];
       if (!prevPendingUploads) {
         return {};
       }
       const newPendingUploads = {};
       let pendingUploadChanged = false;
       for (const localID in prevPendingUploads) {
         const pendingUpload = prevPendingUploads[localID];
         if (uploadIDsToRetry.has(localID) && !pendingUpload.serverID) {
           newPendingUploads[localID] = {
             ...pendingUpload,
             failed: null,
             progressPercent: 0,
             abort: null,
           };
           pendingUploadChanged = true;
         } else {
           newPendingUploads[localID] = pendingUpload;
         }
       }
       if (!pendingUploadChanged) {
         return {};
       }
       return {
         pendingUploads: {
           ...prevState.pendingUploads,
           [newThreadID]: newPendingUploads,
         },
       };
     });
 
     this.uploadFiles(threadInfo.id, uploadsToRetry);
   }
 
   addReply = (message: string) => {
     this.replyCallbacks.forEach(addReplyCallback => addReplyCallback(message));
   };
 
   addReplyListener = (callbackReply: (message: string) => void) => {
     this.replyCallbacks.push(callbackReply);
   };
 
   removeReplyListener = (callbackReply: (message: string) => void) => {
     this.replyCallbacks = this.replyCallbacks.filter(
       candidate => candidate !== callbackReply,
     );
   };
 
   render() {
     const { activeChatThreadID } = this.props;
     const inputState = activeChatThreadID
       ? this.inputStateSelector(activeChatThreadID)(this.state)
       : null;
     return (
       <InputStateContext.Provider value={inputState}>
         {this.props.children}
       </InputStateContext.Provider>
     );
   }
 }
 
 const ConnectedInputStateContainer: React.ComponentType<BaseProps> = React.memo<BaseProps>(
   function ConnectedInputStateContainer(props) {
     const exifRotate = useSelector(state => {
       const browser = detectBrowser(state.userAgent);
       return (
         !browser || (browser.name !== 'safari' && browser.name !== 'chrome')
       );
     });
     const activeChatThreadID = useSelector(
       state => state.navInfo.activeChatThreadID,
     );
     const viewerID = useSelector(
       state => state.currentUserInfo && state.currentUserInfo.id,
     );
     const messageStoreMessages = useSelector(
       state => state.messageStore.messages,
     );
     const locallyUniqueToRealizedThreadIDs = useSelector(state =>
       locallyUniqueToRealizedThreadIDsSelector(state.threadStore.threadInfos),
     );
     const calendarQuery = useSelector(nonThreadCalendarQuery);
     const callUploadMultimedia = useServerCall(uploadMultimedia);
     const callDeleteUpload = useServerCall(deleteUpload);
     const callSendMultimediaMessage = useServerCall(sendMultimediaMessage);
     const callSendTextMessage = useServerCall(sendTextMessage);
     const callNewThread = useServerCall(newThread);
     const dispatch = useDispatch();
     const dispatchActionPromise = useDispatchActionPromise();
     const modalContext = useModalContext();
 
+    const [sendCallbacks, setSendCallbacks] = React.useState<
+      $ReadOnlyArray<() => mixed>,
+    >([]);
+    const registerSendCallback = React.useCallback((callback: () => mixed) => {
+      setSendCallbacks(prevCallbacks => [...prevCallbacks, callback]);
+    }, []);
+    const unregisterSendCallback = React.useCallback(
+      (callback: () => mixed) => {
+        setSendCallbacks(prevCallbacks =>
+          prevCallbacks.filter(candidate => candidate !== callback),
+        );
+      },
+      [],
+    );
+
     return (
       <InputStateContainer
         {...props}
         activeChatThreadID={activeChatThreadID}
         viewerID={viewerID}
         messageStoreMessages={messageStoreMessages}
         exifRotate={exifRotate}
         locallyUniqueRealizedThreadIDs={locallyUniqueToRealizedThreadIDs}
         calendarQuery={calendarQuery}
         uploadMultimedia={callUploadMultimedia}
         deleteUpload={callDeleteUpload}
         sendMultimediaMessage={callSendMultimediaMessage}
         sendTextMessage={callSendTextMessage}
         newThread={callNewThread}
         dispatch={dispatch}
         dispatchActionPromise={dispatchActionPromise}
         pushModal={modalContext.pushModal}
+        sendCallbacks={sendCallbacks}
+        registerSendCallback={registerSendCallback}
+        unregisterSendCallback={unregisterSendCallback}
       />
     );
   },
 );
 
 export default ConnectedInputStateContainer;
diff --git a/web/input/input-state.js b/web/input/input-state.js
index 70eb4230f..8c6a3035a 100644
--- a/web/input/input-state.js
+++ b/web/input/input-state.js
@@ -1,66 +1,68 @@
 // @flow
 
 import * as React from 'react';
 
 import {
   type MediaType,
   type Dimensions,
   type MediaMissionStep,
 } from 'lib/types/media-types';
 import type { RawTextMessageInfo } from 'lib/types/messages/text';
 import type { ThreadInfo } from 'lib/types/thread-types';
 
 export type PendingMultimediaUpload = {
   localID: string,
   // Pending uploads are assigned a serverID once they are complete
   serverID: ?string,
   // Pending uploads are assigned a messageID once they are sent
   messageID: ?string,
   // This is set to truthy if the upload fails for whatever reason
   failed: ?string,
   file: File,
   mediaType: MediaType,
   dimensions: ?Dimensions,
   uri: string,
   loop: boolean,
   // URLs created with createObjectURL aren't considered "real". The distinction
   // is required because those "fake" URLs must be disposed properly
   uriIsReal: boolean,
   progressPercent: number,
   // This is set once the network request begins and used if the upload is
   // cancelled
   abort: ?() => void,
   steps: MediaMissionStep[],
   selectTime: number,
 };
 
 // This type represents the input state for a particular thread
 export type InputState = {
   pendingUploads: $ReadOnlyArray<PendingMultimediaUpload>,
   assignedUploads: {
     [messageID: string]: $ReadOnlyArray<PendingMultimediaUpload>,
   },
   draft: string,
   appendFiles: (files: $ReadOnlyArray<File>) => Promise<boolean>,
   cancelPendingUpload: (localUploadID: string) => void,
   sendTextMessage: (
     messageInfo: RawTextMessageInfo,
     threadInfo: ThreadInfo,
   ) => Promise<void>,
   createMultimediaMessage: (localID: number, threadInfo: ThreadInfo) => void,
   setDraft: (draft: string) => void,
   messageHasUploadFailure: (localMessageID: string) => boolean,
   retryMultimediaMessage: (
     localMessageID: string,
     threadInfo: ThreadInfo,
   ) => void,
   addReply: (text: string) => void,
   addReplyListener: ((message: string) => void) => void,
   removeReplyListener: ((message: string) => void) => void,
+  registerSendCallback: (() => mixed) => void,
+  unregisterSendCallback: (() => mixed) => void,
 };
 
 const InputStateContext: React.Context<?InputState> = React.createContext<?InputState>(
   null,
 );
 
 export { InputStateContext };