diff --git a/lib/shared/mention-utils.js b/lib/shared/mention-utils.js
--- a/lib/shared/mention-utils.js
+++ b/lib/shared/mention-utils.js
@@ -15,7 +15,7 @@
 
 export type TypeaheadMatchedStrings = {
   +textBeforeAtSymbol: string,
-  +usernamePrefix: string,
+  +textPrefix: string,
 };
 
 export type Selection = {
diff --git a/native/chat/chat-input-bar.react.js b/native/chat/chat-input-bar.react.js
--- a/native/chat/chat-input-bar.react.js
+++ b/native/chat/chat-input-bar.react.js
@@ -552,14 +552,14 @@
     if (typeaheadRegexMatches && !isEditMode) {
       const typeaheadMatchedStrings = {
         textBeforeAtSymbol: typeaheadRegexMatches[1] ?? '',
-        usernamePrefix: typeaheadRegexMatches[4] ?? '',
+        textPrefix: typeaheadRegexMatches[4] ?? '',
       };
 
       const suggestedUsers = getTypeaheadUserSuggestions(
         this.props.userSearchIndex,
         this.props.mentionsCandidates,
         this.props.viewerID,
-        typeaheadMatchedStrings.usernamePrefix,
+        typeaheadMatchedStrings.textPrefix,
       );
 
       if (suggestedUsers.length > 0) {
diff --git a/native/chat/typeahead-tooltip.react.js b/native/chat/typeahead-tooltip.react.js
--- a/native/chat/typeahead-tooltip.react.js
+++ b/native/chat/typeahead-tooltip.react.js
@@ -30,7 +30,7 @@
     focusAndUpdateTextAndSelection,
   } = props;
 
-  const { textBeforeAtSymbol, usernamePrefix } = matchedStrings;
+  const { textBeforeAtSymbol, textPrefix } = matchedStrings;
 
   const styles = useStyles(unboundStyles);
 
@@ -40,7 +40,7 @@
         const { newText, newSelectionStart } = getNewTextAndSelection(
           textBeforeAtSymbol,
           text,
-          usernamePrefix,
+          textPrefix,
           item,
         );
 
@@ -64,7 +64,7 @@
       styles.buttonLabel,
       textBeforeAtSymbol,
       text,
-      usernamePrefix,
+      textPrefix,
       focusAndUpdateTextAndSelection,
     ],
   );
diff --git a/web/chat/chat-input-bar.react.js b/web/chat/chat-input-bar.react.js
--- a/web/chat/chat-input-bar.react.js
+++ b/web/chat/chat-input-bar.react.js
@@ -602,7 +602,7 @@
           ? {
               textBeforeAtSymbol:
                 typeaheadRegexMatches.groups?.textPrefix ?? '',
-              usernamePrefix: typeaheadRegexMatches.groups?.username ?? '',
+              textPrefix: typeaheadRegexMatches.groups?.username ?? '',
             }
           : null,
       [typeaheadRegexMatches],
@@ -630,7 +630,7 @@
           userSearchIndex,
           props.inputState.typeaheadState.frozenMentionsCandidates,
           viewerID,
-          typeaheadMatchedStrings.usernamePrefix,
+          typeaheadMatchedStrings.textPrefix,
         );
       }, [
         userSearchIndex,
diff --git a/web/chat/typeahead-tooltip.react.js b/web/chat/typeahead-tooltip.react.js
--- a/web/chat/typeahead-tooltip.react.js
+++ b/web/chat/typeahead-tooltip.react.js
@@ -26,7 +26,7 @@
 function TypeaheadTooltip(props: TypeaheadTooltipProps): React.Node {
   const { inputState, textarea, matchedStrings, suggestedUsers } = props;
 
-  const { textBeforeAtSymbol, usernamePrefix } = matchedStrings;
+  const { textBeforeAtSymbol, textPrefix } = matchedStrings;
 
   const [isVisibleForAnimation, setIsVisibleForAnimation] =
     React.useState(false);
@@ -63,7 +63,7 @@
         inputStateSetTextCursorPosition: inputState.setTextCursorPosition,
         suggestedUsers,
         textBeforeAtSymbol,
-        usernamePrefix,
+        textPrefix,
       }),
     [
       inputState.draft,
@@ -71,7 +71,7 @@
       inputState.setTextCursorPosition,
       suggestedUsers,
       textBeforeAtSymbol,
-      usernamePrefix,
+      textPrefix,
     ],
   );
 
diff --git a/web/utils/typeahead-utils.js b/web/utils/typeahead-utils.js
--- a/web/utils/typeahead-utils.js
+++ b/web/utils/typeahead-utils.js
@@ -82,7 +82,7 @@
   +inputStateSetTextCursorPosition: (newPosition: number) => mixed,
   +suggestedUsers: $ReadOnlyArray<RelativeMemberInfo>,
   +textBeforeAtSymbol: string,
-  +usernamePrefix: string,
+  +textPrefix: string,
 };
 
 function getTypeaheadTooltipActions(
@@ -94,7 +94,7 @@
     inputStateSetTextCursorPosition,
     suggestedUsers,
     textBeforeAtSymbol,
-    usernamePrefix,
+    textPrefix,
   } = params;
   return suggestedUsers
     .filter(
@@ -106,7 +106,7 @@
         const { newText, newSelectionStart } = getNewTextAndSelection(
           textBeforeAtSymbol,
           inputStateDraft,
-          usernamePrefix,
+          textPrefix,
           suggestedUser,
         );