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/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/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/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