diff --git a/src/components/dms/dialogs/NewChatDialog.tsx b/src/components/dms/dialogs/NewChatDialog.tsx
index 4cca14bd0a..7ee103ef9b 100644
--- a/src/components/dms/dialogs/NewChatDialog.tsx
+++ b/src/components/dms/dialogs/NewChatDialog.tsx
@@ -1,5 +1,4 @@
 import {useCallback} from 'react'
-import {ChatBskyGroupCreateGroup} from '@atproto/api'
 import {Trans, useLingui} from '@lingui/react/macro'
 
 import {useRequireEmailVerification} from '#/lib/hooks/useRequireEmailVerification'
@@ -88,29 +87,27 @@ export function NewChat({
       let errorMessage = l`An issue occurred starting the group chat, please try again.`
       if (isNetworkError(error)) {
         errorMessage = l`A network error occurred. Please check your internet connection.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.AccountSuspendedError
-      ) {
-        errorMessage = l`Suspended accounts cannot participate in a group chat.`
-      } else if (error instanceof ChatBskyGroupCreateGroup.BlockedActorError) {
-        errorMessage = l`One of the selected recipients has blocked you and cannot be messaged.`
-      } else if (
-        error instanceof
-        ChatBskyGroupCreateGroup.NewAccountCannotCreateGroupError
-      ) {
-        errorMessage = l`You cannot create a group chat yet.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.NotFollowedBySenderError
-      ) {
-        errorMessage = l`A selected recipient is not followed by the sender.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.RecipientNotFoundError
-      ) {
-        errorMessage = l`Unable to find a selected recipient.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.UserForbidsGroupsError
-      ) {
-        errorMessage = l`One of the selected recipients does not allow group chats.`
+      } else {
+        switch (matchXrpcError(error, chat.bsky.group.createGroup)) {
+          case 'AccountSuspended':
+            errorMessage = l`Suspended accounts cannot participate in a group chat.`
+            break
+          case 'BlockedActor':
+            errorMessage = l`One of the selected recipients has blocked you and cannot be messaged.`
+            break
+          case 'NewAccountCannotCreateGroup':
+            errorMessage = l`You cannot create a group chat yet.`
+            break
+          case 'NotFollowedBySender':
+            errorMessage = l`A selected recipient is not followed by the sender.`
+            break
+          case 'RecipientNotFound':
+            errorMessage = l`Unable to find a selected recipient.`
+            break
+          case 'UserForbidsGroups':
+            errorMessage = l`One of the selected recipients does not allow group chats.`
+            break
+        }
       }
       Toast.show(errorMessage, {
         type: 'error',
diff --git a/src/components/dms/dialogs/ShareViaChatDialog.tsx b/src/components/dms/dialogs/ShareViaChatDialog.tsx
index 6dfb6145f7..f26dd47a57 100644
--- a/src/components/dms/dialogs/ShareViaChatDialog.tsx
+++ b/src/components/dms/dialogs/ShareViaChatDialog.tsx
@@ -1,5 +1,4 @@
 import {useCallback, useState} from 'react'
-import {ChatBskyGroupCreateGroup} from '@atproto/api'
 import {useLingui} from '@lingui/react/macro'
 
 import {isNetworkError} from '#/lib/strings/errors'
@@ -104,29 +103,27 @@ function SendViaChatDialogInner({
       let errorMessage = l`An issue occurred starting the group chat, please try again.`
       if (isNetworkError(error)) {
         errorMessage = l`A network error occurred. Please check your internet connection.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.AccountSuspendedError
-      ) {
-        errorMessage = l`Suspended accounts cannot participate in a group chat.`
-      } else if (error instanceof ChatBskyGroupCreateGroup.BlockedActorError) {
-        errorMessage = l`One of the selected recipients has blocked you and cannot be messaged.`
-      } else if (
-        error instanceof
-        ChatBskyGroupCreateGroup.NewAccountCannotCreateGroupError
-      ) {
-        errorMessage = l`You cannot create a group chat yet.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.NotFollowedBySenderError
-      ) {
-        errorMessage = l`A selected recipient is not followed by the sender.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.RecipientNotFoundError
-      ) {
-        errorMessage = l`Unable to find a selected recipient.`
-      } else if (
-        error instanceof ChatBskyGroupCreateGroup.UserForbidsGroupsError
-      ) {
-        errorMessage = l`One of the selected recipients does not allow group chats.`
+      } else {
+        switch (matchXrpcError(error, chat.bsky.group.createGroup)) {
+          case 'AccountSuspended':
+            errorMessage = l`Suspended accounts cannot participate in a group chat.`
+            break
+          case 'BlockedActor':
+            errorMessage = l`One of the selected recipients has blocked you and cannot be messaged.`
+            break
+          case 'NewAccountCannotCreateGroup':
+            errorMessage = l`You cannot create a group chat yet.`
+            break
+          case 'NotFollowedBySender':
+            errorMessage = l`A selected recipient is not followed by the sender.`
+            break
+          case 'RecipientNotFound':
+            errorMessage = l`Unable to find a selected recipient.`
+            break
+          case 'UserForbidsGroups':
+            errorMessage = l`One of the selected recipients does not allow group chats.`
+            break
+        }
       }
       Toast.show(errorMessage, {
         type: 'error',
diff --git a/src/components/intents/GroupChatJoinDialog.tsx b/src/components/intents/GroupChatJoinDialog.tsx
index 7c506a634d..53782ae271 100644
--- a/src/components/intents/GroupChatJoinDialog.tsx
+++ b/src/components/intents/GroupChatJoinDialog.tsx
@@ -1,11 +1,6 @@
 import {useEffect} from 'react'
 import {View} from 'react-native'
-import {
-  ChatBskyGroupDefs,
-  ChatBskyGroupRequestJoin,
-  ChatBskyGroupWithdrawJoinRequest,
-  moderateProfile,
-} from '@atproto/api'
+import {ChatBskyGroupDefs, moderateProfile} from '@atproto/api'
 import {Plural, Trans, useLingui} from '@lingui/react/macro'
 import {useNavigation} from '@react-navigation/native'
 import {useQueryClient} from '@tanstack/react-query'
@@ -16,6 +11,7 @@ import {makeProfileLink} from '#/lib/routes/links'
 import {type NavigationProp} from '#/lib/routes/types'
 import {isNetworkError} from '#/lib/strings/errors'
 import {sanitizeHandle} from '#/lib/strings/handles'
+import {matchXrpcError} from '#/lib/xrpc-error'
 import {logger} from '#/logger'
 import {useModerationOpts} from '#/state/preferences/moderation-opts'
 import {
@@ -49,6 +45,7 @@ import {Loader} from '#/components/Loader'
 import * as Toast from '#/components/Toast'
 import {Text} from '#/components/Typography'
 import {useAnalytics} from '#/analytics'
+import {chat} from '#/lexicons'
 import {ProfileBadges} from '../ProfileBadges'
 
 export function GroupChatJoinDialog() {
@@ -147,33 +144,37 @@ function GroupChatJoinDialogContent({code}: {code?: string}) {
         let errorMessage = l`Failed to join the group chat. Please try again.`
         if (isNetworkError(error)) {
           errorMessage = l`There was a problem with your internet connection, please try again`
-        } else if (error instanceof ChatBskyGroupRequestJoin.ConvoLockedError) {
-          errorMessage = l`This conversation is locked.`
-        } else if (
-          error instanceof ChatBskyGroupRequestJoin.FollowRequiredError
-        ) {
-          errorMessage = l`Only followers can join this group chat.`
-        } else if (error instanceof ChatBskyGroupRequestJoin.InvalidCodeError) {
-          errorMessage = l`Invalid group chat code.`
-        } else if (
-          error instanceof ChatBskyGroupRequestJoin.LinkDisabledError
-        ) {
-          errorMessage = l`This invite link has been disabled.`
-        } else if (
-          error instanceof ChatBskyGroupRequestJoin.MemberLimitReachedError
-        ) {
-          errorMessage = l`The member limit has been reached.`
-          const preview = data?.joinLinkPreviews[0]
-          if (
-            ChatBskyGroupDefs.isJoinLinkPreviewView(preview) &&
-            preview.convo?.id
-          ) {
-            ax.metric('groupchat:join:memberLimitReached', {
-              convoId: preview.convo.id,
-            })
+        } else {
+          switch (matchXrpcError(error, chat.bsky.group.requestJoin)) {
+            case 'ConvoLocked':
+              errorMessage = l`This conversation is locked.`
+              break
+            case 'FollowRequired':
+              errorMessage = l`Only followers can join this group chat.`
+              break
+            case 'InvalidCode':
+              errorMessage = l`Invalid group chat code.`
+              break
+            case 'LinkDisabled':
+              errorMessage = l`This invite link has been disabled.`
+              break
+            case 'MemberLimitReached': {
+              errorMessage = l`The member limit has been reached.`
+              const preview = data?.joinLinkPreviews[0]
+              if (
+                ChatBskyGroupDefs.isJoinLinkPreviewView(preview) &&
+                preview.convo?.id
+              ) {
+                ax.metric('groupchat:join:memberLimitReached', {
+                  convoId: preview.convo.id,
+                })
+              }
+              break
+            }
+            case 'UserKicked':
+              errorMessage = l`You have been previously removed from this group and can’t join it using this link.`
+              break
           }
-        } else if (error instanceof ChatBskyGroupRequestJoin.UserKickedError) {
-          errorMessage = l`You have been previously removed from this group and can’t join it using this link.`
         }
         Toast.show(errorMessage)
       },
@@ -194,8 +195,8 @@ function GroupChatJoinDialogContent({code}: {code?: string}) {
         if (isNetworkError(error)) {
           errorMessage = l`There was a problem with your internet connection, please try again`
         } else if (
-          error instanceof
-          ChatBskyGroupWithdrawJoinRequest.InvalidJoinRequestError
+          matchXrpcError(error, chat.bsky.group.withdrawJoinRequest) ===
+          'InvalidJoinRequest'
         ) {
           errorMessage = l`Invalid rescind request.`
         }
diff --git a/src/components/moderation/BlockDialog.tsx b/src/components/moderation/BlockDialog.tsx
index 5ec9e4d9e4..d576e071d7 100644
--- a/src/components/moderation/BlockDialog.tsx
+++ b/src/components/moderation/BlockDialog.tsx
@@ -1,6 +1,6 @@
 import {useState} from 'react'
 import {View} from 'react-native'
-import {type ChatBskyConvoDefs, ChatBskyGroupRemoveMembers} from '@atproto/api'
+import {type ChatBskyConvoDefs} from '@atproto/api'
 import {Trans, useLingui} from '@lingui/react/macro'
 import {useQueryClient} from '@tanstack/react-query'
 
@@ -309,14 +309,15 @@ function MutualGroupChat({
         let errorMessage = l`Could not remove member.`
         if (isNetworkError(error)) {
           errorMessage = l`A network error occurred. Please check your internet connection.`
-        } else if (
-          error instanceof ChatBskyGroupRemoveMembers.InvalidConvoError
-        ) {
-          errorMessage = l`Chat not found.`
-        } else if (
-          error instanceof ChatBskyGroupRemoveMembers.InsufficientRoleError
-        ) {
-          errorMessage = l`You must be a chat owner to remove a member.`
+        } else {
+          switch (matchXrpcError(error, chat.bsky.group.removeMembers)) {
+            case 'InvalidConvo':
+              errorMessage = l`Chat not found.`
+              break
+            case 'InsufficientRole':
+              errorMessage = l`You must be a chat owner to remove a member.`
+              break
+          }
         }
         Toast.show(errorMessage, {type: 'error'})
       },
diff --git a/src/screens/Messages/JoinRequests.tsx b/src/screens/Messages/JoinRequests.tsx
index ffe3fb219e..d8d6ff9b06 100644
--- a/src/screens/Messages/JoinRequests.tsx
+++ b/src/screens/Messages/JoinRequests.tsx
@@ -1,10 +1,6 @@
 import {useState} from 'react'
 import {View} from 'react-native'
-import {
-  ChatBskyGroupApproveJoinRequest,
-  type ChatBskyGroupListJoinRequests,
-  ChatBskyGroupRejectJoinRequest,
-} from '@atproto/api'
+import {type ChatBskyGroupListJoinRequests} from '@atproto/api'
 import {Plural, Trans, useLingui} from '@lingui/react/macro'
 import {useNavigation} from '@react-navigation/native'
 import {type InfiniteData, useQueryClient} from '@tanstack/react-query'
@@ -16,6 +12,7 @@ import {
   type NativeStackScreenProps,
   type NavigationProp,
 } from '#/lib/routes/types'
+import {matchXrpcError} from '#/lib/xrpc-error'
 import {logger} from '#/logger'
 import {ConvoProvider, useConvo} from '#/state/messages/convo'
 import {ConvoStatus} from '#/state/messages/convo/types'
@@ -43,6 +40,7 @@ import * as ProfileCard from '#/components/ProfileCard'
 import * as Toast from '#/components/Toast'
 import {Text} from '#/components/Typography'
 import {useAnalytics} from '#/analytics'
+import {chat} from '#/lexicons'
 import type * as bsky from '#/types/bsky'
 import {InviteLinkDialog} from './components/InviteLinkDialog'
 
@@ -190,19 +188,18 @@ function JoinRequestsList({
         let errorMessage = l`Failed to accept join request`
         if (isNetworkError(error)) {
           errorMessage = l`A network error occurred. Please check your internet connection.`
-        } else if (
-          error instanceof ChatBskyGroupApproveJoinRequest.InvalidConvoError
-        ) {
-          errorMessage = l`Conversation not found.`
-        } else if (
-          error instanceof ChatBskyGroupApproveJoinRequest.InsufficientRoleError
-        ) {
-          errorMessage = l`Only admins can accept join requests.`
-        } else if (
-          error instanceof
-          ChatBskyGroupApproveJoinRequest.MemberLimitReachedError
-        ) {
-          errorMessage = l`The member limit has been reached.`
+        } else {
+          switch (matchXrpcError(error, chat.bsky.group.approveJoinRequest)) {
+            case 'InvalidConvo':
+              errorMessage = l`Conversation not found.`
+              break
+            case 'InsufficientRole':
+              errorMessage = l`Only admins can accept join requests.`
+              break
+            case 'MemberLimitReached':
+              errorMessage = l`The member limit has been reached.`
+              break
+          }
         }
         Toast.show(errorMessage, {type: 'error'})
       },
@@ -223,14 +220,15 @@ function JoinRequestsList({
         let errorMessage = l`Failed to reject join request`
         if (isNetworkError(error)) {
           errorMessage = l`A network error occurred. Please check your internet connection.`
-        } else if (
-          error instanceof ChatBskyGroupRejectJoinRequest.InvalidConvoError
-        ) {
-          errorMessage = l`Conversation not found.`
-        } else if (
-          error instanceof ChatBskyGroupRejectJoinRequest.InsufficientRoleError
-        ) {
-          errorMessage = l`Only admins can reject join requests.`
+        } else {
+          switch (matchXrpcError(error, chat.bsky.group.rejectJoinRequest)) {
+            case 'InvalidConvo':
+              errorMessage = l`Conversation not found.`
+              break
+            case 'InsufficientRole':
+              errorMessage = l`Only admins can reject join requests.`
+              break
+          }
         }
         Toast.show(errorMessage, {type: 'error'})
       },
diff --git a/src/screens/Messages/components/OutgoingRequestListItem.tsx b/src/screens/Messages/components/OutgoingRequestListItem.tsx
index b5dcdf08df..eb62f24b81 100644
--- a/src/screens/Messages/components/OutgoingRequestListItem.tsx
+++ b/src/screens/Messages/components/OutgoingRequestListItem.tsx
@@ -1,11 +1,9 @@
 import {View} from 'react-native'
-import {
-  type ChatBskyGroupDefs,
-  ChatBskyGroupWithdrawJoinRequest,
-} from '@atproto/api'
+import {type ChatBskyGroupDefs} from '@atproto/api'
 import {Trans, useLingui} from '@lingui/react/macro'
 
 import {isNetworkError} from '#/lib/strings/errors'
+import {matchXrpcError} from '#/lib/xrpc-error'
 import {useWithdrawJoinGroupChatRequest} from '#/state/queries/messages/withdraw-join-group-chat'
 import {TimeElapsed} from '#/view/com/util/TimeElapsed'
 import {atoms as a, useTheme, web} from '#/alf'
@@ -14,6 +12,7 @@ import {createStaticClick, Link} from '#/components/Link'
 import * as Prompt from '#/components/Prompt'
 import * as Toast from '#/components/Toast'
 import {Text} from '#/components/Typography'
+import {chat} from '#/lexicons'
 
 export function OutgoingRequestListItem({
   convo: convoView,
@@ -35,8 +34,8 @@ export function OutgoingRequestListItem({
         if (isNetworkError(error)) {
           errorMessage = l`There was a problem with your internet connection, please try again`
         } else if (
-          error instanceof
-          ChatBskyGroupWithdrawJoinRequest.InvalidJoinRequestError
+          matchXrpcError(error, chat.bsky.group.withdrawJoinRequest) ===
+          'InvalidJoinRequest'
         ) {
           errorMessage = l`Invalid rescind request.`
         }
diff --git a/src/state/queries/join-links.ts b/src/state/queries/join-links.ts
index ca1db05558..e5dbbc9bed 100644
--- a/src/state/queries/join-links.ts
+++ b/src/state/queries/join-links.ts
@@ -1,17 +1,19 @@
 import {useCallback} from 'react'
 import {
   type $Typed,
-  AtpAgent,
   ChatBskyGroupDefs,
   type ChatBskyGroupGetJoinLinkPreviews,
 } from '@atproto/api'
+import {type Client} from '@atproto/lex'
 import {type QueryClient, useQuery, useQueryClient} from '@tanstack/react-query'
 
-import {CHAT_SERVICE, DM_SERVICE_HEADERS} from '#/lib/constants'
+import {CHAT_SERVICE} from '#/lib/constants'
+import {createLexClient} from '#/lib/lexClient'
 import {logger} from '#/logger'
 import {STALE} from '#/state/queries/index'
 import {createQueryKey, type StructuredQueryKey} from '#/state/queries/util'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 
 /**
  * The three preview shapes we currently support. Excludes the `{$type: string}`
@@ -154,23 +156,39 @@ export function invalidateJoinLinkPreviewsForConvo(
   })
 }
 
+let publicChatClient: Client | undefined
+
+/**
+ * The unauthenticated {@link Client} for the chat service, used to resolve join
+ * links before the viewer has a session.
+ *
+ * It talks to {@link CHAT_SERVICE} directly rather than proxying through a PDS,
+ * so no `atproto-proxy` header is involved. A single module-level instance,
+ * because there is no session to scope it to and reconstructing it per call
+ * would be waste.
+ *
+ * Unlike the public appview client this does NOT wrap `networkAwareFetch`,
+ * matching the plain-fetch behavior of the ad-hoc agent it replaces: a
+ * logged-out link resolution failing says nothing useful about the session's
+ * reachability, so it should not move the app-wide network signal.
+ */
+function getPublicChatClient(): Client {
+  return (publicChatClient ??= createLexClient({service: CHAT_SERVICE}))
+}
+
 async function fetchJoinLinkPreviews({
-  agent,
+  client,
   codes,
   hasSession,
 }: {
-  agent: AtpAgent
+  client: Client
   codes: string[]
   hasSession: boolean
 }) {
-  const previewAgent = new AtpAgent({service: CHAT_SERVICE})
-  const res = hasSession
-    ? await agent.chat.bsky.group.getJoinLinkPreviews(
-        {codes},
-        {headers: DM_SERVICE_HEADERS},
-      )
-    : await previewAgent.chat.bsky.group.getJoinLinkPreviews({codes})
-  return res.data
+  return await (hasSession ? client : getPublicChatClient()).call(
+    chat.bsky.group.getJoinLinkPreviews,
+    {codes},
+  )
 }
 
 export function useJoinLinkPreviewsQuery({
@@ -188,14 +206,14 @@ export function useJoinLinkPreviewsQuery({
    */
   initialData?: ChatBskyGroupGetJoinLinkPreviews.OutputSchema
 }) {
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useQuery({
     queryKey: createJoinLinkPreviewQueryKey({codes: codes ?? [], hasSession}),
     queryFn: async () => {
       if (!codes) throw new Error('No invite code')
       try {
-        return await fetchJoinLinkPreviews({agent, codes, hasSession})
+        return await fetchJoinLinkPreviews({client, codes, hasSession})
       } catch (error) {
         logger.error('Failed to fetch join link preview', {safeMessage: error})
         throw error
@@ -208,13 +226,13 @@ export function useJoinLinkPreviewsQuery({
 }
 
 export function usePrefetchJoinLinkPreviews() {
-  const agent = useAgent()
+  const client = useChatClient()
   const queryClient = useQueryClient()
 
   return ({codes, hasSession}: {codes: string[]; hasSession: boolean}) => {
     return queryClient.prefetchQuery({
       queryKey: createJoinLinkPreviewQueryKey({codes, hasSession}),
-      queryFn: () => fetchJoinLinkPreviews({agent, codes, hasSession}),
+      queryFn: () => fetchJoinLinkPreviews({client, codes, hasSession}),
       staleTime: STALE.SECONDS.FIFTEEN,
     })
   }
@@ -226,7 +244,7 @@ export function usePrefetchJoinLinkPreviews() {
  * Returns undefined if the preview can't be resolved.
  */
 export function useGetJoinLinkPreview() {
-  const agent = useAgent()
+  const client = useChatClient()
   const queryClient = useQueryClient()
 
   return useCallback(
@@ -241,7 +259,7 @@ export function useGetJoinLinkPreview() {
         const data = await queryClient.fetchQuery({
           queryKey: createJoinLinkPreviewQueryKey({codes: [code], hasSession}),
           queryFn: () =>
-            fetchJoinLinkPreviews({agent, codes: [code], hasSession}),
+            fetchJoinLinkPreviews({client, codes: [code], hasSession}),
           staleTime: STALE.SECONDS.FIFTEEN,
         })
         const found = data.joinLinkPreviews[0]
@@ -251,6 +269,6 @@ export function useGetJoinLinkPreview() {
         return undefined
       }
     },
-    [agent, queryClient],
+    [client, queryClient],
   )
 }
diff --git a/src/state/queries/messages/add-group-members.ts b/src/state/queries/messages/add-group-members.ts
index b5ddacbbff..bf4f8a8f4e 100644
--- a/src/state/queries/messages/add-group-members.ts
+++ b/src/state/queries/messages/add-group-members.ts
@@ -4,16 +4,17 @@ import {
   type ChatBskyConvoListConvos,
   type ChatBskyGroupAddMembers,
 } from '@atproto/api'
+import {type DidString} from '@atproto/syntax'
 import {
   type InfiniteData,
   useMutation,
   useQueryClient,
 } from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
 import {useProfileQuery} from '#/state/queries/profile'
-import {useAgent, useSession} from '#/state/session'
+import {useChatClient, useSession} from '#/state/session'
+import {chat} from '#/lexicons'
 import type * as bsky from '#/types/bsky'
 import {RQKEY as CONVO_KEY} from './conversation'
 import {RQKEY_ROOT as CONVO_LIST_KEY} from './list-conversations'
@@ -30,7 +31,7 @@ export function useAddGroupMembers(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
   const {currentAccount} = useSession()
   const {data: myProfile} = useProfileQuery({did: currentAccount?.did})
 
@@ -42,11 +43,11 @@ export function useAddGroupMembers(
       profiles: bsky.profile.AnyProfileView[]
     }) => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} = await agent.chat.bsky.group.addMembers(
-        {convoId, members},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
-      return data
+      return await client.call(chat.bsky.group.addMembers, {
+        convoId,
+        // callers pass already-resolved actor dids
+        members: members as DidString[],
+      })
     },
     onMutate: ({profiles}) => {
       if (!convoId) return
diff --git a/src/state/queries/messages/create-group-chat.ts b/src/state/queries/messages/create-group-chat.ts
index 9f8aadc7d0..4a78a2be6a 100644
--- a/src/state/queries/messages/create-group-chat.ts
+++ b/src/state/queries/messages/create-group-chat.ts
@@ -1,9 +1,10 @@
 import {type ChatBskyGroupCreateGroup} from '@atproto/api'
+import {type DidString} from '@atproto/syntax'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {precacheConvoQuery} from './conversation'
 
 export function useCreateGroupChat({
@@ -14,16 +15,15 @@ export function useCreateGroupChat({
   onError?: (error: Error) => void
 }) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async ({name, members}: {name: string; members: string[]}) => {
-      const {data} = await agent.chat.bsky.group.createGroup(
-        {name, members},
-        {headers: DM_SERVICE_HEADERS},
-      )
-
-      return data
+      return await client.call(chat.bsky.group.createGroup, {
+        name,
+        // callers pass already-resolved actor dids
+        members: members as DidString[],
+      })
     },
     onSuccess: data => {
       precacheConvoQuery(queryClient, data.convo)
diff --git a/src/state/queries/messages/create-join-link.ts b/src/state/queries/messages/create-join-link.ts
index fbac855466..57269b93e3 100644
--- a/src/state/queries/messages/create-join-link.ts
+++ b/src/state/queries/messages/create-join-link.ts
@@ -5,9 +5,9 @@ import {
 } from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {
   rollbackConvoOptimistic,
   updateConvoOptimistic,
@@ -24,7 +24,7 @@ export function useCreateJoinLink(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async ({
@@ -35,11 +35,11 @@ export function useCreateJoinLink(
       requireApproval: boolean
     }) => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} = await agent.chat.bsky.group.createJoinLink(
-        {convoId, joinRule, requireApproval},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
-      return data
+      return await client.call(chat.bsky.group.createJoinLink, {
+        convoId,
+        joinRule,
+        requireApproval,
+      })
     },
     onMutate: ({joinRule, requireApproval}) => {
       if (!convoId) return
diff --git a/src/state/queries/messages/disable-join-link.ts b/src/state/queries/messages/disable-join-link.ts
index c143feb6cc..b995dbcc6f 100644
--- a/src/state/queries/messages/disable-join-link.ts
+++ b/src/state/queries/messages/disable-join-link.ts
@@ -4,10 +4,10 @@ import {
 } from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
 import {invalidateJoinLinkPreviewsForCode} from '#/state/queries/join-links'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {
   rollbackConvoOptimistic,
   updateConvoOptimistic,
@@ -24,16 +24,12 @@ export function useDisableJoinLink(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async () => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} = await agent.chat.bsky.group.disableJoinLink(
-        {convoId},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
-      return data
+      return await client.call(chat.bsky.group.disableJoinLink, {convoId})
     },
     onMutate: () => {
       if (!convoId) return
diff --git a/src/state/queries/messages/edit-group-chat-name.ts b/src/state/queries/messages/edit-group-chat-name.ts
index ef2a72f4ec..ecc73fd3d3 100644
--- a/src/state/queries/messages/edit-group-chat-name.ts
+++ b/src/state/queries/messages/edit-group-chat-name.ts
@@ -1,9 +1,9 @@
 import {ChatBskyConvoDefs, type ChatBskyGroupEditGroup} from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {
   rollbackConvoOptimistic,
   updateConvoOptimistic,
@@ -20,16 +20,15 @@ export function useEditGroupChatName(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async ({name: groupName}: {name: string}) => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} = await agent.chat.bsky.group.editGroup(
-        {convoId, name: groupName},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
-      return data
+      return await client.call(chat.bsky.group.editGroup, {
+        convoId,
+        name: groupName,
+      })
     },
     onMutate: ({name: groupName}) => {
       if (!convoId) return
diff --git a/src/state/queries/messages/edit-join-link.ts b/src/state/queries/messages/edit-join-link.ts
index 7e34ce88d9..7870c1f7e3 100644
--- a/src/state/queries/messages/edit-join-link.ts
+++ b/src/state/queries/messages/edit-join-link.ts
@@ -5,9 +5,9 @@ import {
 } from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {
   rollbackConvoOptimistic,
   updateConvoOptimistic,
@@ -24,7 +24,7 @@ export function useEditJoinLink(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async ({
@@ -35,11 +35,11 @@ export function useEditJoinLink(
       requireApproval: boolean
     }) => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} = await agent.chat.bsky.group.editJoinLink(
-        {convoId, joinRule, requireApproval},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
-      return data
+      return await client.call(chat.bsky.group.editJoinLink, {
+        convoId,
+        joinRule,
+        requireApproval,
+      })
     },
     onMutate: ({joinRule, requireApproval}) => {
       if (!convoId) return
diff --git a/src/state/queries/messages/enable-join-link.ts b/src/state/queries/messages/enable-join-link.ts
index 4febc85441..ef3b168068 100644
--- a/src/state/queries/messages/enable-join-link.ts
+++ b/src/state/queries/messages/enable-join-link.ts
@@ -1,10 +1,10 @@
 import {ChatBskyConvoDefs, type ChatBskyGroupEnableJoinLink} from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
 import {invalidateJoinLinkPreviewsForCode} from '#/state/queries/join-links'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {
   rollbackConvoOptimistic,
   updateConvoOptimistic,
@@ -21,16 +21,12 @@ export function useEnableJoinLink(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async () => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} = await agent.chat.bsky.group.enableJoinLink(
-        {convoId},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
-      return data
+      return await client.call(chat.bsky.group.enableJoinLink, {convoId})
     },
     onMutate: () => {
       if (!convoId) return
diff --git a/src/state/queries/messages/join-requests.ts b/src/state/queries/messages/join-requests.ts
index 179dfafaaf..d36ebd60ae 100644
--- a/src/state/queries/messages/join-requests.ts
+++ b/src/state/queries/messages/join-requests.ts
@@ -4,15 +4,16 @@ import {
   type ChatBskyGroupListJoinRequests,
   type ChatBskyGroupRejectJoinRequest,
 } from '@atproto/api'
+import {type DidString} from '@atproto/syntax'
 import {
   type InfiniteData,
   useMutation,
   useQueryClient,
 } from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {listConvoMembersQueryKey} from './list-convo-members'
 import {createListJoinRequestsQueryKey} from './list-join-requests'
 
@@ -34,21 +35,28 @@ export function useJoinRequestMutation<A extends JoinRequestAction>(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async ({member}: {member: string}) => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} =
+      // callers pass an already-resolved actor did
+      const memberDid = member as DidString
+      const data =
         action === 'approve'
-          ? await agent.chat.bsky.group.approveJoinRequest(
-              {convoId, member},
-              {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-            )
-          : await agent.chat.bsky.group.rejectJoinRequest(
-              {convoId, member},
-              {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-            )
+          ? await client.call(chat.bsky.group.approveJoinRequest, {
+              convoId,
+              member: memberDid,
+            })
+          : await client.call(chat.bsky.group.rejectJoinRequest, {
+              convoId,
+              member: memberDid,
+            })
+      /*
+       * The two branches have different output schemas, so the union cannot be
+       * narrowed from the `action` value alone - the cast carries the generic's
+       * mapping through, exactly as the pre-migration code did.
+       */
       return data as JoinRequestOutput<A>
     },
     onMutate: ({member}) => {
diff --git a/src/state/queries/messages/list-join-requests.ts b/src/state/queries/messages/list-join-requests.ts
index 64a999c118..bbb82eeca5 100644
--- a/src/state/queries/messages/list-join-requests.ts
+++ b/src/state/queries/messages/list-join-requests.ts
@@ -2,10 +2,10 @@ import {useEffect} from 'react'
 import {ChatBskyConvoDefs} from '@atproto/api'
 import {useInfiniteQuery, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {useMessagesEventBus} from '#/state/messages/events'
 import {createQueryKey} from '#/state/queries/util'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {STALE} from '..'
 
 export const JOIN_REQUESTS_THRESHOLD = 20
@@ -22,7 +22,7 @@ export function useListJoinRequestsQuery({
   convoId: string | undefined
   enabled?: boolean
 }) {
-  const agent = useAgent()
+  const client = useChatClient()
   const queryClient = useQueryClient()
   const messagesBus = useMessagesEventBus()
   const isEnabled = enabled !== false && !!convoId
@@ -54,11 +54,12 @@ export function useListJoinRequestsQuery({
     enabled: isEnabled,
     queryKey: createListJoinRequestsQueryKey({convoId: convoId ?? ''}),
     queryFn: async ({pageParam}) => {
-      const {data} = await agent.chat.bsky.group.listJoinRequests(
-        {convoId: convoId!, cursor: pageParam, limit: JOIN_REQUESTS_THRESHOLD},
-        {headers: DM_SERVICE_HEADERS},
-      )
-      return data
+      return await client.call(chat.bsky.group.listJoinRequests, {
+        // guarded by `isEnabled`
+        convoId: convoId!,
+        cursor: pageParam,
+        limit: JOIN_REQUESTS_THRESHOLD,
+      })
     },
     initialPageParam: undefined as string | undefined,
     getNextPageParam: page => page.cursor,
diff --git a/src/state/queries/messages/list-mutual-groups.ts b/src/state/queries/messages/list-mutual-groups.ts
index 9ff4a1da09..65743a45e7 100644
--- a/src/state/queries/messages/list-mutual-groups.ts
+++ b/src/state/queries/messages/list-mutual-groups.ts
@@ -1,8 +1,9 @@
+import {type DidString} from '@atproto/syntax'
 import {useInfiniteQuery} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {createQueryKey} from '#/state/queries/util'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 
 const listMutualGroupsQueryKeyRoot = 'list-mutual-groups'
 
@@ -18,7 +19,7 @@ export function useListMutualGroupsQuery({
   enabled?: boolean
   limit?: number
 }) {
-  const agent = useAgent()
+  const client = useChatClient()
   const isEnabled = enabled !== false && !!subject
 
   return useInfiniteQuery({
@@ -27,11 +28,12 @@ export function useListMutualGroupsQuery({
     enabled: isEnabled,
     queryKey: createListMutualGroupsQueryKey({subject: subject ?? ''}),
     queryFn: async ({pageParam}) => {
-      const {data} = await agent.chat.bsky.group.listMutualGroups(
-        {subject: subject!, cursor: pageParam, limit},
-        {headers: DM_SERVICE_HEADERS},
-      )
-      return data
+      return await client.call(chat.bsky.group.listMutualGroups, {
+        // guarded by `enabled`, and callers pass a resolved actor did
+        subject: subject as DidString,
+        cursor: pageParam,
+        limit,
+      })
     },
     initialPageParam: undefined as string | undefined,
     getNextPageParam: page => page.cursor,
diff --git a/src/state/queries/messages/mark-join-request-read.ts b/src/state/queries/messages/mark-join-request-read.ts
index ae6d7e88a7..3dfd995af0 100644
--- a/src/state/queries/messages/mark-join-request-read.ts
+++ b/src/state/queries/messages/mark-join-request-read.ts
@@ -1,9 +1,9 @@
 import {ChatBskyConvoDefs} from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {RQKEY as CONVO_KEY} from './conversation'
 import {
   type ConvoListQueryData,
@@ -12,15 +12,12 @@ import {
 
 export function useMarkJoinRequestsRead(convoId: string | undefined) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async () => {
       if (!convoId) throw new Error('No convoId provided')
-      await agent.chat.bsky.group.updateJoinRequestsRead(
-        {convoId},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
+      await client.call(chat.bsky.group.updateJoinRequestsRead, {convoId})
     },
     onMutate: () => {
       if (!convoId) return
diff --git a/src/state/queries/messages/remove-from-group.ts b/src/state/queries/messages/remove-from-group.ts
index 95f246be5a..10437ad7e9 100644
--- a/src/state/queries/messages/remove-from-group.ts
+++ b/src/state/queries/messages/remove-from-group.ts
@@ -4,15 +4,16 @@ import {
   type ChatBskyConvoListConvos,
   type ChatBskyGroupRemoveMembers,
 } from '@atproto/api'
+import {type DidString} from '@atproto/syntax'
 import {
   type InfiniteData,
   useMutation,
   useQueryClient,
 } from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
 import {RQKEY as CONVO_KEY} from './conversation'
 import {RQKEY_ROOT as CONVO_LIST_KEY} from './list-conversations'
 import {listConvoMembersQueryKey} from './list-convo-members'
@@ -28,16 +29,16 @@ export function useRemoveFromGroupChat(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const client = useChatClient()
 
   return useMutation({
     mutationFn: async ({members}: {members: string[]}) => {
       if (!convoId) throw new Error('No convoId provided')
-      const {data} = await agent.chat.bsky.group.removeMembers(
-        {convoId, members},
-        {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-      )
-      return data
+      return await client.call(chat.bsky.group.removeMembers, {
+        convoId,
+        // callers pass already-resolved actor dids
+        members: members as DidString[],
+      })
     },
     onMutate: ({members}) => {
       if (!convoId) return
diff --git a/src/state/queries/messages/request-join-group-chat.ts b/src/state/queries/messages/request-join-group-chat.ts
index f4d5650346..b0a1922007 100644
--- a/src/state/queries/messages/request-join-group-chat.ts
+++ b/src/state/queries/messages/request-join-group-chat.ts
@@ -1,9 +1,9 @@
 import {type ChatBskyGroupRequestJoin} from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent, useSession} from '#/state/session'
+import {useChatClient, useSession} from '#/state/session'
+import {chat} from '#/lexicons'
 import {RQKEY_ROOT as REQUESTS_RQKEY_ROOT} from './list-conversation-requests'
 
 export function useRequestJoinGroupChat({
@@ -13,7 +13,7 @@ export function useRequestJoinGroupChat({
   onSuccess?: (data: ChatBskyGroupRequestJoin.OutputSchema) => void
   onError?: (error: Error) => void
 } = {}) {
-  const agent = useAgent()
+  const client = useChatClient()
   const queryClient = useQueryClient()
   const {hasSession} = useSession()
 
@@ -22,11 +22,7 @@ export function useRequestJoinGroupChat({
       if (!hasSession) throw new Error('Must be logged in to join')
       if (!code) throw new Error('No invite code')
 
-      const res = await agent.chat.bsky.group.requestJoin(
-        {code},
-        {headers: DM_SERVICE_HEADERS},
-      )
-      return res.data
+      return await client.call(chat.bsky.group.requestJoin, {code})
     },
     onSuccess: data => {
       void queryClient.invalidateQueries({queryKey: [REQUESTS_RQKEY_ROOT]})
diff --git a/src/state/queries/messages/withdraw-join-group-chat.ts b/src/state/queries/messages/withdraw-join-group-chat.ts
index 2ede8c941d..736128ee25 100644
--- a/src/state/queries/messages/withdraw-join-group-chat.ts
+++ b/src/state/queries/messages/withdraw-join-group-chat.ts
@@ -1,9 +1,9 @@
 import {type ChatBskyGroupWithdrawJoinRequest} from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
 import {logger} from '#/logger'
-import {useAgent, useSession} from '#/state/session'
+import {useChatClient, useSession} from '#/state/session'
+import {chat} from '#/lexicons'
 import {
   type ConvoRequestListQueryData,
   optimisticDeleteJoinRequest,
@@ -17,7 +17,7 @@ export function useWithdrawJoinGroupChatRequest({
   onSuccess?: (data: ChatBskyGroupWithdrawJoinRequest.OutputSchema) => void
   onError?: (error: Error) => void
 } = {}) {
-  const agent = useAgent()
+  const client = useChatClient()
   const queryClient = useQueryClient()
   const {hasSession} = useSession()
 
@@ -27,11 +27,7 @@ export function useWithdrawJoinGroupChatRequest({
         throw new Error('Must be logged in to withdraw a join request')
       if (!convoId) throw new Error('No convoId provided')
 
-      const res = await agent.chat.bsky.group.withdrawJoinRequest(
-        {convoId},
-        {headers: DM_SERVICE_HEADERS},
-      )
-      return res.data
+      return await client.call(chat.bsky.group.withdrawJoinRequest, {convoId})
     },
     onSuccess: (data, {convoId}) => {
       queryClient.setQueriesData<ConvoRequestListQueryData>(