diff --git a/lib/types/media-types.js b/lib/types/media-types.js
index c189ffe5a..cf10bf800 100644
--- a/lib/types/media-types.js
+++ b/lib/types/media-types.js
@@ -1,496 +1,496 @@
 // @flow
 
 import type { Shape } from './core';
 import { type Platform } from './device-types';
 
 export type Dimensions = $ReadOnly<{|
-  height: number,
-  width: number,
+  +height: number,
+  +width: number,
 |}>;
 
 export type MediaType = 'photo' | 'video';
 
 export type Image = {|
-  id: string,
-  uri: string,
-  type: 'photo',
-  dimensions: Dimensions,
+  +id: string,
+  +uri: string,
+  +type: 'photo',
+  +dimensions: Dimensions,
   // stored on native only during creation in case retry needed after state lost
-  localMediaSelection?: NativeMediaSelection,
+  +localMediaSelection?: NativeMediaSelection,
 |};
 
 export type Video = {|
-  id: string,
-  uri: string,
-  type: 'video',
-  dimensions: Dimensions,
-  loop?: boolean,
+  +id: string,
+  +uri: string,
+  +type: 'video',
+  +dimensions: Dimensions,
+  +loop?: boolean,
   // stored on native only during creation in case retry needed after state lost
-  localMediaSelection?: NativeMediaSelection,
+  +localMediaSelection?: NativeMediaSelection,
 |};
 
 export type Media = Image | Video;
 
 export type Corners = Shape<{|
-  topLeft: boolean,
-  topRight: boolean,
-  bottomLeft: boolean,
-  bottomRight: boolean,
+  +topLeft: boolean,
+  +topRight: boolean,
+  +bottomLeft: boolean,
+  +bottomRight: boolean,
 |}>;
 
 export type MediaInfo =
   | {|
       ...Image,
-      corners: Corners,
-      index: number,
+      +corners: Corners,
+      +index: number,
     |}
   | {|
       ...Video,
-      corners: Corners,
-      index: number,
+      +corners: Corners,
+      +index: number,
     |};
 
 export type UploadMultimediaResult = {|
-  id: string,
-  uri: string,
-  dimensions: Dimensions,
-  mediaType: MediaType,
-  loop: boolean,
+  +id: string,
+  +uri: string,
+  +dimensions: Dimensions,
+  +mediaType: MediaType,
+  +loop: boolean,
 |};
 
 export type UpdateMultimediaMessageMediaPayload = {|
-  messageID: string,
-  currentMediaID: string,
-  mediaUpdate: Shape<Media>,
+  +messageID: string,
+  +currentMediaID: string,
+  +mediaUpdate: Shape<Media>,
 |};
 
 export type UploadDeletionRequest = {|
-  id: string,
+  +id: string,
 |};
 
 export type FFmpegStatistics = {|
   // seconds of video being processed per second
   +speed: number,
   // total milliseconds of video processed so far
   +time: number,
   // total result file size in bytes so far
   +size: number,
   +videoQuality: number,
   +videoFrameNumber: number,
   +videoFps: number,
   +bitrate: number,
 |};
 
 export type VideoProbeMediaMissionStep = {|
-  step: 'video_probe',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  path: string,
-  validFormat: boolean,
-  duration: ?number, // seconds
-  codec: ?string,
-  format: ?$ReadOnlyArray<string>,
-  dimensions: ?Dimensions,
+  +step: 'video_probe',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +path: string,
+  +validFormat: boolean,
+  +duration: ?number, // seconds
+  +codec: ?string,
+  +format: ?$ReadOnlyArray<string>,
+  +dimensions: ?Dimensions,
 |};
 
 export type ReadFileHeaderMediaMissionStep = {|
-  step: 'read_file_header',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  uri: string,
-  mime: ?string,
-  mediaType: ?MediaType,
+  +step: 'read_file_header',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +uri: string,
+  +mime: ?string,
+  +mediaType: ?MediaType,
 |};
 
 export type DetermineFileTypeMediaMissionStep = {|
-  step: 'determine_file_type',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  inputFilename: string,
-  outputMIME: ?string,
-  outputMediaType: ?MediaType,
-  outputFilename: ?string,
+  +step: 'determine_file_type',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +inputFilename: string,
+  +outputMIME: ?string,
+  +outputMediaType: ?MediaType,
+  +outputFilename: ?string,
 |};
 
 export type FrameCountMediaMissionStep = {|
-  step: 'frame_count',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number,
-  path: string,
-  mime: string,
-  hasMultipleFrames: ?boolean,
+  +step: 'frame_count',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number,
+  +path: string,
+  +mime: string,
+  +hasMultipleFrames: ?boolean,
 |};
 
 export type DisposeTemporaryFileMediaMissionStep = {|
-  step: 'dispose_temporary_file',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  path: string,
+  +step: 'dispose_temporary_file',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +path: string,
 |};
 
 export type MakeDirectoryMediaMissionStep = {|
-  step: 'make_directory',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  path: string,
+  +step: 'make_directory',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +path: string,
 |};
 
 export type AndroidScanFileMediaMissionStep = {|
-  step: 'android_scan_file',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  path: string,
+  +step: 'android_scan_file',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +path: string,
 |};
 
 export type FetchFileHashMediaMissionStep = {|
-  step: 'fetch_file_hash',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  path: string,
-  hash: ?string,
+  +step: 'fetch_file_hash',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +path: string,
+  +hash: ?string,
 |};
 
 export type CopyFileMediaMissionStep = {|
-  step: 'copy_file',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  source: string,
-  destination: string,
+  +step: 'copy_file',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +source: string,
+  +destination: string,
 |};
 
 export type GetOrientationMediaMissionStep = {|
-  step: 'exif_fetch',
-  success: boolean,
-  exceptionMessage: ?string,
-  time: number, // ms
-  orientation: ?number,
+  +step: 'exif_fetch',
+  +success: boolean,
+  +exceptionMessage: ?string,
+  +time: number, // ms
+  +orientation: ?number,
 |};
 
 export type MediaLibrarySelection =
   | {|
-      step: 'photo_library',
-      dimensions: Dimensions,
-      filename: string,
-      uri: string,
-      mediaNativeID: string,
-      selectTime: number, // ms timestamp
-      sendTime: number, // ms timestamp
-      retries: number,
-    |}
-  | {|
-      step: 'video_library',
-      dimensions: Dimensions,
-      filename: string,
-      uri: string,
-      mediaNativeID: string,
-      selectTime: number, // ms timestamp
-      sendTime: number, // ms timestamp
-      retries: number,
-      duration: number, // seconds
+      +step: 'photo_library',
+      +dimensions: Dimensions,
+      +filename: string,
+      +uri: string,
+      +mediaNativeID: string,
+      +selectTime: number, // ms timestamp
+      +sendTime: number, // ms timestamp
+      +retries: number,
+    |}
+  | {|
+      +step: 'video_library',
+      +dimensions: Dimensions,
+      +filename: string,
+      +uri: string,
+      +mediaNativeID: string,
+      +selectTime: number, // ms timestamp
+      +sendTime: number, // ms timestamp
+      +retries: number,
+      +duration: number, // seconds
     |};
 
 export type PhotoCapture = {|
-  step: 'photo_capture',
-  time: number, // ms
-  dimensions: Dimensions,
-  filename: string,
-  uri: string,
-  captureTime: number, // ms timestamp
-  selectTime: number, // ms timestamp
-  sendTime: number, // ms timestamp
-  retries: number,
+  +step: 'photo_capture',
+  +time: number, // ms
+  +dimensions: Dimensions,
+  +filename: string,
+  +uri: string,
+  +captureTime: number, // ms timestamp
+  +selectTime: number, // ms timestamp
+  +sendTime: number, // ms timestamp
+  +retries: number,
 |};
 
 export type PhotoPaste = {|
   +step: 'photo_paste',
   +dimensions: Dimensions,
   +filename: string,
   +uri: string,
   +selectTime: number, // ms timestamp
   +sendTime: number, // ms timestamp
   +retries: number,
 |};
 
 export type NativeMediaSelection =
   | MediaLibrarySelection
   | PhotoCapture
   | PhotoPaste;
 
 export type MediaMissionStep =
   | NativeMediaSelection
   | {|
-      step: 'web_selection',
-      filename: string,
-      size: number, // in bytes
-      mime: string,
-      selectTime: number, // ms timestamp
+      +step: 'web_selection',
+      +filename: string,
+      +size: number, // in bytes
+      +mime: string,
+      +selectTime: number, // ms timestamp
     |}
   | {|
-      step: 'asset_info_fetch',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      localURI: ?string,
-      orientation: ?number,
+      +step: 'asset_info_fetch',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +localURI: ?string,
+      +orientation: ?number,
     |}
   | {|
-      step: 'stat_file',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      uri: string,
-      fileSize: ?number,
+      +step: 'stat_file',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +uri: string,
+      +fileSize: ?number,
     |}
   | ReadFileHeaderMediaMissionStep
   | DetermineFileTypeMediaMissionStep
   | FrameCountMediaMissionStep
   | {|
-      step: 'photo_manipulation',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      manipulation: Object,
-      newMIME: ?string,
-      newDimensions: ?Dimensions,
-      newURI: ?string,
+      +step: 'photo_manipulation',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +manipulation: Object,
+      +newMIME: ?string,
+      +newDimensions: ?Dimensions,
+      +newURI: ?string,
     |}
   | VideoProbeMediaMissionStep
   | {|
-      step: 'video_ffmpeg_transcode',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      returnCode: ?number,
-      newPath: ?string,
-      stats: ?FFmpegStatistics,
+      +step: 'video_ffmpeg_transcode',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +returnCode: ?number,
+      +newPath: ?string,
+      +stats: ?FFmpegStatistics,
     |}
   | DisposeTemporaryFileMediaMissionStep
   | {|
-      step: 'save_media',
-      uri: string,
-      time: number, // ms timestamp
+      +step: 'save_media',
+      +uri: string,
+      +time: number, // ms timestamp
     |}
   | {|
-      step: 'permissions_check',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      platform: Platform,
-      permissions: $ReadOnlyArray<string>,
+      +step: 'permissions_check',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +platform: Platform,
+      +permissions: $ReadOnlyArray<string>,
     |}
   | MakeDirectoryMediaMissionStep
   | AndroidScanFileMediaMissionStep
   | {|
-      step: 'ios_save_to_library',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      uri: string,
+      +step: 'ios_save_to_library',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +uri: string,
     |}
   | {|
-      step: 'fetch_blob',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      inputURI: string,
-      uri: string,
-      size: ?number,
-      mime: ?string,
+      +step: 'fetch_blob',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +inputURI: string,
+      +uri: string,
+      +size: ?number,
+      +mime: ?string,
     |}
   | {|
-      step: 'data_uri_from_blob',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      first255Chars: ?string,
+      +step: 'data_uri_from_blob',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +first255Chars: ?string,
     |}
   | {|
-      step: 'array_buffer_from_blob',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
+      +step: 'array_buffer_from_blob',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
     |}
   | {|
-      step: 'mime_check',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      mime: ?string,
+      +step: 'mime_check',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +mime: ?string,
     |}
   | {|
-      step: 'write_file',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      path: string,
-      length: number,
+      +step: 'write_file',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +path: string,
+      +length: number,
     |}
   | FetchFileHashMediaMissionStep
   | CopyFileMediaMissionStep
   | GetOrientationMediaMissionStep
   | {|
-      step: 'preload_image',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      uri: string,
-      dimensions: ?Dimensions,
-    |}
-  | {|
-      step: 'reorient_image',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      uri: ?string,
-    |}
-  | {|
-      step: 'upload',
-      success: boolean,
-      exceptionMessage: ?string,
-      time: number, // ms
-      inputFilename: string,
-      outputMediaType: ?MediaType,
-      outputURI: ?string,
-      outputDimensions: ?Dimensions,
-      outputLoop: ?boolean,
-      hasWiFi?: boolean,
-    |}
-  | {|
-      step: 'wait_for_capture_uri_unload',
-      success: boolean,
-      time: number, // ms
-      uri: string,
+      +step: 'preload_image',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +uri: string,
+      +dimensions: ?Dimensions,
+    |}
+  | {|
+      +step: 'reorient_image',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +uri: ?string,
+    |}
+  | {|
+      +step: 'upload',
+      +success: boolean,
+      +exceptionMessage: ?string,
+      +time: number, // ms
+      +inputFilename: string,
+      +outputMediaType: ?MediaType,
+      +outputURI: ?string,
+      +outputDimensions: ?Dimensions,
+      +outputLoop: ?boolean,
+      +hasWiFi?: boolean,
+    |}
+  | {|
+      +step: 'wait_for_capture_uri_unload',
+      +success: boolean,
+      +time: number, // ms
+      +uri: string,
     |};
 
 export type MediaMissionFailure =
   | {|
-      success: false,
-      reason: 'no_file_path',
+      +success: false,
+      +reason: 'no_file_path',
     |}
   | {|
-      success: false,
-      reason: 'file_stat_failed',
-      uri: string,
+      +success: false,
+      +reason: 'file_stat_failed',
+      +uri: string,
     |}
   | {|
-      success: false,
-      reason: 'photo_manipulation_failed',
-      size: number, // in bytes
+      +success: false,
+      +reason: 'photo_manipulation_failed',
+      +size: number, // in bytes
     |}
   | {|
-      success: false,
-      reason: 'media_type_fetch_failed',
-      detectedMIME: ?string,
+      +success: false,
+      +reason: 'media_type_fetch_failed',
+      +detectedMIME: ?string,
     |}
   | {|
-      success: false,
-      reason: 'mime_type_mismatch',
-      reportedMediaType: MediaType,
-      reportedMIME: string,
-      detectedMIME: string,
+      +success: false,
+      +reason: 'mime_type_mismatch',
+      +reportedMediaType: MediaType,
+      +reportedMIME: string,
+      +detectedMIME: string,
     |}
   | {|
-      success: false,
-      reason: 'http_upload_failed',
-      exceptionMessage: ?string,
+      +success: false,
+      +reason: 'http_upload_failed',
+      +exceptionMessage: ?string,
     |}
   | {|
-      success: false,
-      reason: 'video_too_long',
-      duration: number, // in seconds
+      +success: false,
+      +reason: 'video_too_long',
+      +duration: number, // in seconds
     |}
   | {|
-      success: false,
-      reason: 'video_probe_failed',
+      +success: false,
+      +reason: 'video_probe_failed',
     |}
   | {|
-      success: false,
-      reason: 'video_transcode_failed',
+      +success: false,
+      +reason: 'video_transcode_failed',
     |}
   | {|
-      success: false,
-      reason: 'processing_exception',
-      time: number, // ms
-      exceptionMessage: ?string,
+      +success: false,
+      +reason: 'processing_exception',
+      +time: number, // ms
+      +exceptionMessage: ?string,
     |}
   | {|
-      success: false,
-      reason: 'save_unsupported',
+      +success: false,
+      +reason: 'save_unsupported',
     |}
   | {|
-      success: false,
-      reason: 'missing_permission',
+      +success: false,
+      +reason: 'missing_permission',
     |}
   | {|
-      success: false,
-      reason: 'make_directory_failed',
+      +success: false,
+      +reason: 'make_directory_failed',
     |}
   | {|
-      success: false,
-      reason: 'resolve_failed',
-      uri: string,
+      +success: false,
+      +reason: 'resolve_failed',
+      +uri: string,
     |}
   | {|
-      success: false,
-      reason: 'save_to_library_failed',
-      uri: string,
+      +success: false,
+      +reason: 'save_to_library_failed',
+      +uri: string,
     |}
   | {|
-      success: false,
-      reason: 'fetch_failed',
+      +success: false,
+      +reason: 'fetch_failed',
     |}
   | {|
-      success: false,
-      reason: 'data_uri_failed',
+      +success: false,
+      +reason: 'data_uri_failed',
     |}
   | {|
-      success: false,
-      reason: 'array_buffer_failed',
+      +success: false,
+      +reason: 'array_buffer_failed',
     |}
   | {|
-      success: false,
-      reason: 'mime_check_failed',
-      mime: ?string,
+      +success: false,
+      +reason: 'mime_check_failed',
+      +mime: ?string,
     |}
   | {|
-      success: false,
-      reason: 'write_file_failed',
+      +success: false,
+      +reason: 'write_file_failed',
     |}
   | {|
-      success: false,
-      reason: 'fetch_file_hash_failed',
+      +success: false,
+      +reason: 'fetch_file_hash_failed',
     |}
   | {|
-      success: false,
-      reason: 'copy_file_failed',
+      +success: false,
+      +reason: 'copy_file_failed',
     |}
   | {|
-      success: false,
-      reason: 'exif_fetch_failed',
+      +success: false,
+      +reason: 'exif_fetch_failed',
     |}
   | {|
-      success: false,
-      reason: 'reorient_image_failed',
+      +success: false,
+      +reason: 'reorient_image_failed',
     |}
   | {|
-      success: false,
-      reason: 'web_sibling_validation_failed',
+      +success: false,
+      +reason: 'web_sibling_validation_failed',
     |};
 
-export type MediaMissionResult = MediaMissionFailure | {| success: true |};
+export type MediaMissionResult = MediaMissionFailure | {| +success: true |};
 
 export type MediaMission = {|
-  steps: $ReadOnlyArray<MediaMissionStep>,
-  result: MediaMissionResult,
-  userTime: number,
-  totalTime: number,
+  +steps: $ReadOnlyArray<MediaMissionStep>,
+  +result: MediaMissionResult,
+  +userTime: number,
+  +totalTime: number,
 |};