From b236f274c3524a0e091a12741b6b3855ae9283ef Mon Sep 17 00:00:00 2001
From: Samuel Newman <mozzius@protonmail.com>
Date: Fri, 5 Jun 2026 23:17:29 +0300
Subject: [PATCH] [Chat] Enforce limits for group size (#10753)

---
 .../dialogs/SearchablePeopleList.tsx          |  1 -
 src/components/dms/AddMembersFlow.tsx         | 11 ++++
 src/components/dms/InitiateChatFlow.tsx       | 34 ++++++++++-
 .../dms/components/GroupChatProfileCard.tsx   | 58 +++++++++++--------
 src/lib/constants.ts                          |  2 +
 .../Messages/ConversationSettings/prompts.tsx | 35 +++++++++--
 6 files changed, 109 insertions(+), 32 deletions(-)

diff --git a/src/components/dialogs/SearchablePeopleList.tsx b/src/components/dialogs/SearchablePeopleList.tsx
index 614234c17f..cc07900bea 100644
--- a/src/components/dialogs/SearchablePeopleList.tsx
+++ b/src/components/dialogs/SearchablePeopleList.tsx
@@ -667,7 +667,6 @@ function SearchInput({
       />
 
       <TextInput
-        // @ts-ignore bottom sheet input types issue — esb
         ref={inputRef}
         placeholder={l`Search`}
         value={value}
diff --git a/src/components/dms/AddMembersFlow.tsx b/src/components/dms/AddMembersFlow.tsx
index 749e6976ed..ae2945d2ce 100644
--- a/src/components/dms/AddMembersFlow.tsx
+++ b/src/components/dms/AddMembersFlow.tsx
@@ -11,6 +11,7 @@ import {Trans, useLingui} from '@lingui/react/macro'
 
 import {useModerationOpts} from '#/state/preferences/moderation-opts'
 import {useActorAutocompleteQuery} from '#/state/queries/actor-autocomplete'
+import {useChatActorStatusQuery} from '#/state/queries/messages/get-status'
 import {useListConvoMembersQuery} from '#/state/queries/messages/list-convo-members'
 import {useProfileFollowsQuery} from '#/state/queries/profile-follows'
 import {useSession} from '#/state/session'
@@ -141,6 +142,15 @@ export function AddMembersFlow({
     [memberListData],
   )
 
+  const {data: chatStatus} = useChatActorStatusQuery()
+  const groupMemberLimit = chatStatus?.groupMemberLimit
+  // The existing members (including the viewer) already occupy slots, so the
+  // number of people that can still be added is whatever's left.
+  const remainingSlots =
+    groupMemberLimit !== undefined
+      ? Math.max(0, groupMemberLimit - memberListData.length)
+      : undefined
+
   const [{groupChatDids, groupChatProfiles}, dispatch] = useReducer(reducer, {
     groupChatDids: [],
     groupChatProfiles: [],
@@ -471,6 +481,7 @@ export function AddMembersFlow({
       values={groupChatDids}
       onChange={setGroupChatMembers}
       type="checkbox"
+      maxSelections={remainingSlots}
       label={l`Add group chat members`}
       style={web([a.contents])}>
       <Dialog.InnerFlatList
diff --git a/src/components/dms/InitiateChatFlow.tsx b/src/components/dms/InitiateChatFlow.tsx
index 32da1e3e5b..108041e678 100644
--- a/src/components/dms/InitiateChatFlow.tsx
+++ b/src/components/dms/InitiateChatFlow.tsx
@@ -10,8 +10,10 @@ import {LayoutAnimation, type TextInput, View} from 'react-native'
 import {moderateProfile, type ModerationOpts} from '@atproto/api'
 import {Trans, useLingui} from '@lingui/react/macro'
 
+import {MAX_GROUP_NAME_GRAPHEME_LENGTH} from '#/lib/constants'
 import {sanitizeDisplayName} from '#/lib/strings/display-names'
 import {sanitizeHandle} from '#/lib/strings/handles'
+import {isOverMaxGraphemeCount} from '#/lib/strings/helpers'
 import {useModerationOpts} from '#/state/preferences/moderation-opts'
 import {useActorAutocompleteQuery} from '#/state/queries/actor-autocomplete'
 import {useChatActorStatusQuery} from '#/state/queries/messages/get-status'
@@ -212,6 +214,7 @@ export function InitiateChatFlow({
 
   const {data: chatStatus} = useChatActorStatusQuery()
   const canCreateGroups = chatStatus?.canCreateGroups ?? true
+  const groupMemberLimit = chatStatus?.groupMemberLimit
 
   const [searchText, setSearchText] = useState('')
 
@@ -458,6 +461,11 @@ export function InitiateChatFlow({
     }
   }, [])
 
+  const groupNameTooLong = isOverMaxGraphemeCount({
+    text: groupName,
+    maxCount: MAX_GROUP_NAME_GRAPHEME_LENGTH,
+  })
+
   let buttonLabel = l`Continue to group name`
   let buttonText = l`Next`
   let handleButtonPress = handlePressNext
@@ -470,7 +478,7 @@ export function InitiateChatFlow({
       buttonText = l`Create`
       handleButtonPress = handlePressConfirm
       showButton = true
-      isButtonDisabled = groupName === ''
+      isButtonDisabled = groupName === '' || groupNameTooLong
       break
   }
 
@@ -564,7 +572,7 @@ export function InitiateChatFlow({
             {chatState === ChatState.GROUP_NAME ? (
               <View
                 style={[a.w_full, a.relative, web(a.pt_md), native(a.pt_xl)]}>
-                <TextField.Root>
+                <TextField.Root isInvalid={groupNameTooLong}>
                   <TextField.Input
                     label={l`Group name`}
                     value={groupName}
@@ -573,6 +581,7 @@ export function InitiateChatFlow({
                     selectTextOnFocus={IS_NATIVE}
                     autoFocus={false}
                     accessibilityRole="text"
+                    clearButtonMode="while-editing"
                     autoCorrect={false}
                     autoComplete="off"
                     autoCapitalize="none"
@@ -582,6 +591,20 @@ export function InitiateChatFlow({
                     }
                   />
                 </TextField.Root>
+                {groupNameTooLong ? (
+                  <Text
+                    style={[
+                      a.text_sm,
+                      a.mt_xs,
+                      a.font_semi_bold,
+                      {color: t.palette.negative_400},
+                    ]}>
+                    <Trans>
+                      Group name is too long. The maximum number of characters
+                      is {MAX_GROUP_NAME_GRAPHEME_LENGTH}.
+                    </Trans>
+                  </Text>
+                ) : null}
               </View>
             ) : (
               <UserSearchInput
@@ -622,6 +645,8 @@ export function InitiateChatFlow({
       handleButtonPress,
       buttonText,
       groupName,
+      groupNameTooLong,
+      t.palette.negative_400,
       searchText,
       control,
       showChatProfileTabs,
@@ -664,6 +689,11 @@ export function InitiateChatFlow({
       values={groupChatDids}
       onChange={setGroupChatMembers}
       type="checkbox"
+      maxSelections={
+        // groupMemberLimit counts the creator, who is added implicitly, so
+        // reserve one slot for them
+        groupMemberLimit ? groupMemberLimit - 1 : undefined
+      }
       label={
         chatState === ChatState.NEW_GROUP_CHAT
           ? l`Select group chat members`
diff --git a/src/components/dms/components/GroupChatProfileCard.tsx b/src/components/dms/components/GroupChatProfileCard.tsx
index c5438464e8..b40f2581a6 100644
--- a/src/components/dms/components/GroupChatProfileCard.tsx
+++ b/src/components/dms/components/GroupChatProfileCard.tsx
@@ -34,32 +34,40 @@ export function GroupChatProfileCard({
       name={profile.did}
       label={displayName}
       style={[a.flex_1, a.py_sm, a.px_lg]}>
-      <View style={[a.flex_grow, !enabled ? {opacity: 0.5} : null]}>
-        <ProfileCard.Header>
-          <ProfileCard.Avatar
-            profile={profile}
-            moderationOpts={moderationOpts}
-            size={44}
-            disabledPreview
-          />
-          <View>
-            <ProfileCard.Name
-              profile={profile}
-              moderationOpts={moderationOpts}
-            />
-            {enabled ? (
-              <ProfileCard.Handle profile={profile} />
-            ) : (
-              <Text
-                style={[a.leading_snug, t.atoms.text_contrast_high]}
-                numberOfLines={2}>
-                <Trans>{handle} can’t be added</Trans>
-              </Text>
-            )}
+      {({disabled, selected}) => (
+        <>
+          <View
+            style={[
+              a.flex_grow,
+              !enabled || (disabled && !selected) ? {opacity: 0.5} : null,
+            ]}>
+            <ProfileCard.Header>
+              <ProfileCard.Avatar
+                profile={profile}
+                moderationOpts={moderationOpts}
+                size={44}
+                disabledPreview
+              />
+              <View>
+                <ProfileCard.Name
+                  profile={profile}
+                  moderationOpts={moderationOpts}
+                />
+                {enabled ? (
+                  <ProfileCard.Handle profile={profile} />
+                ) : (
+                  <Text
+                    style={[a.leading_snug, t.atoms.text_contrast_high]}
+                    numberOfLines={2}>
+                    <Trans>{handle} can’t be added</Trans>
+                  </Text>
+                )}
+              </View>
+            </ProfileCard.Header>
           </View>
-        </ProfileCard.Header>
-      </View>
-      {enabled ? <Toggle.Checkbox /> : null}
+          {enabled ? <Toggle.Checkbox /> : null}
+        </>
+      )}
     </Toggle.Item>
   )
 }
diff --git a/src/lib/constants.ts b/src/lib/constants.ts
index 13ae162a85..91d1319c6b 100644
--- a/src/lib/constants.ts
+++ b/src/lib/constants.ts
@@ -67,6 +67,8 @@ export const MAX_DRAFT_GRAPHEME_LENGTH = 1000
 
 export const MAX_DM_GRAPHEME_LENGTH = 1000
 
+export const MAX_GROUP_NAME_GRAPHEME_LENGTH = 50
+
 // Recommended is 100 per: https://www.w3.org/WAI/GL/WCAG20/tests/test3.html
 // but increasing limit per user feedback
 export const MAX_ALT_TEXT = 2000
diff --git a/src/screens/Messages/ConversationSettings/prompts.tsx b/src/screens/Messages/ConversationSettings/prompts.tsx
index f5b980b990..e8b594c0bd 100644
--- a/src/screens/Messages/ConversationSettings/prompts.tsx
+++ b/src/screens/Messages/ConversationSettings/prompts.tsx
@@ -1,10 +1,13 @@
 import {View} from 'react-native'
 import {Trans, useLingui} from '@lingui/react/macro'
 
-import {atoms as a} from '#/alf'
+import {MAX_GROUP_NAME_GRAPHEME_LENGTH} from '#/lib/constants'
+import {isOverMaxGraphemeCount} from '#/lib/strings/helpers'
+import {atoms as a, useTheme} from '#/alf'
 import type * as Dialog from '#/components/Dialog'
 import * as TextField from '#/components/forms/TextField'
 import * as Prompt from '#/components/Prompt'
+import {Text} from '#/components/Typography'
 
 export function EditNamePrompt({
   control,
@@ -17,8 +20,14 @@ export function EditNamePrompt({
   onChangeText: (value: string) => void
   onConfirm: () => void
 }) {
+  const t = useTheme()
   const {t: l} = useLingui()
 
+  const nameTooLong = isOverMaxGraphemeCount({
+    text: value,
+    maxCount: MAX_GROUP_NAME_GRAPHEME_LENGTH,
+  })
+
   return (
     <Prompt.Outer control={control}>
       <>
@@ -27,7 +36,7 @@ export function EditNamePrompt({
             <Trans>Edit group name</Trans>
           </Prompt.TitleText>
           <View style={[a.my_sm]}>
-            <TextField.Root isInvalid={false}>
+            <TextField.Root isInvalid={nameTooLong}>
               <TextField.Input
                 label={l`Edit group name`}
                 placeholder={l`Group name`}
@@ -38,13 +47,31 @@ export function EditNamePrompt({
                 autoComplete="off"
                 autoCorrect={false}
                 autoFocus
-                onSubmitEditing={onConfirm}
+                onSubmitEditing={nameTooLong ? undefined : onConfirm}
               />
             </TextField.Root>
+            {nameTooLong ? (
+              <Text
+                style={[
+                  a.text_sm,
+                  a.mt_xs,
+                  a.font_semi_bold,
+                  {color: t.palette.negative_400},
+                ]}>
+                <Trans>
+                  Group name is too long. The maximum number of characters is{' '}
+                  {MAX_GROUP_NAME_GRAPHEME_LENGTH}.
+                </Trans>
+              </Text>
+            ) : null}
           </View>
         </Prompt.Content>
         <Prompt.Actions>
-          <Prompt.Action cta={l`Save`} onPress={onConfirm} />
+          <Prompt.Action
+            cta={l`Save`}
+            onPress={onConfirm}
+            disabled={nameTooLong}
+          />
           <Prompt.Cancel />
         </Prompt.Actions>
       </>