diff --git a/lib/shared/message-utils.js b/lib/shared/message-utils.js
--- a/lib/shared/message-utils.js
+++ b/lib/shared/message-utils.js
@@ -6,6 +6,7 @@
 import * as React from 'react';
 
 import { codeBlockRegex, type ParserRules } from './markdown.js';
+import type { CreationSideEffectsFunc } from './messages/message-spec.js';
 import { messageSpecs } from './messages/message-specs.js';
 import { threadIsGroupChat } from './thread-utils.js';
 import { useStringForUser } from '../hooks/ens-cache.js';
@@ -538,6 +539,18 @@
   }, [message, username]);
 }
 
+function useMessageCreationSideEffectsFunc<Info: RawMessageInfo>(
+  messageType: $PropertyType<Info, 'type'>,
+): CreationSideEffectsFunc<Info> {
+  const messageSpec = messageSpecs[messageType];
+  invariant(messageSpec, `we're not aware of messageType ${messageType}`);
+  invariant(
+    messageSpec.useCreationSideEffectsFunc,
+    `no useCreationSideEffectsFunc in message spec for ${messageType}`,
+  );
+  return messageSpec.useCreationSideEffectsFunc();
+}
+
 export {
   localIDPrefix,
   messageKey,
@@ -561,4 +574,5 @@
   getMessageTitle,
   mergeThreadMessageInfos,
   useMessagePreview,
+  useMessageCreationSideEffectsFunc,
 };
diff --git a/lib/shared/messages/message-spec.js b/lib/shared/messages/message-spec.js
--- a/lib/shared/messages/message-spec.js
+++ b/lib/shared/messages/message-spec.js
@@ -62,6 +62,12 @@
 });
 export type PushType = $Values<typeof pushTypes>;
 
+export type CreationSideEffectsFunc<RawInfo> = (
+  messageInfo: RawInfo,
+  threadInfo: ThreadInfo,
+  parentThreadInfo: ?ThreadInfo,
+) => Promise<mixed>;
+
 export type MessageSpec<Data, RawInfo, Info> = {
   +messageContentForServerDB?: (data: Data | RawInfo) => string,
   +messageContentForClientDB?: (data: RawInfo) => string,
@@ -103,4 +109,5 @@
   +startsThread?: boolean,
   +threadIDs?: (rawMessageInfo: RawInfo) => $ReadOnlyArray<string>,
   +includedInRepliesCount?: boolean,
+  +useCreationSideEffectsFunc?: () => CreationSideEffectsFunc<RawInfo>,
 };