diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -9,7 +9,6 @@
 import * as React from 'react';
 
 import { getUserAvatarForThread } from './avatar-utils.js';
-import { generatePendingThreadColor } from './color-utils.js';
 import { extractUserMentionsFromText } from './mention-utils.js';
 import { relationshipBlockedInEitherDirection } from './relationship-utils.js';
 import type { SidebarItem } from './sidebar-item-utils.js';
@@ -63,10 +62,8 @@
 } from '../types/minimally-encoded-thread-permissions-types.js';
 import {
   decodeMinimallyEncodedRoleInfo,
-  minimallyEncodeMemberInfo,
   minimallyEncodeRawThreadInfoWithMemberPermissions,
   minimallyEncodeRoleInfo,
-  minimallyEncodeThreadCurrentUserInfo,
 } from '../types/minimally-encoded-thread-permissions-types.js';
 import { userRelationshipStatus } from '../types/relationship-types.js';
 import { defaultThreadSubscription } from '../types/subscription-types.js';
@@ -86,15 +83,12 @@
   threadTypes,
   assertThreadType,
   threadTypeIsThick,
-  assertThinThreadType,
-  assertThickThreadType,
   type ThinThreadType,
 } from '../types/thread-types-enum.js';
 import type {
   LegacyRawThreadInfo,
   ClientLegacyRoleInfo,
   ServerThreadInfo,
-  ThickMemberInfo,
   UserProfileThreadInfo,
   MixedRawThreadInfos,
   LegacyThinRawThreadInfo,
@@ -462,7 +456,7 @@
   +username: ?string,
   ...
 };
-type CreatePendingThreadArgs = {
+export type CreatePendingThreadArgs = {
   +viewerID: string,
   +threadType: ThreadType,
   +members: $ReadOnlyArray<UserIDAndUsername>,
@@ -472,15 +466,8 @@
   +sourceMessageID?: string,
 };
 
-function createPendingThread({
-  viewerID,
-  threadType,
-  members,
-  parentThreadInfo,
-  threadColor,
-  name,
-  sourceMessageID,
-}: CreatePendingThreadArgs): ThreadInfo {
+function createPendingThread(args: CreatePendingThreadArgs): ThreadInfo {
+  const { viewerID, threadType, members, sourceMessageID } = args;
   const now = Date.now();
   if (!members.some(member => member.id === viewerID)) {
     throw new Error(
@@ -511,82 +498,14 @@
     specialRole: specialRoles.DEFAULT_ROLE,
   };
 
-  let rawThreadInfo: RawThreadInfo;
-  if (threadTypeIsThick(threadType)) {
-    const thickThreadType = assertThickThreadType(threadType);
-    rawThreadInfo = {
-      minimallyEncoded: true,
-      thick: true,
-      id: threadID,
-      type: thickThreadType,
-      name: name ?? null,
-      description: null,
-      color: threadColor ?? generatePendingThreadColor(memberIDs),
-      creationTime: now,
-      parentThreadID: parentThreadInfo?.id ?? null,
-      containingThreadID: getContainingThreadID(
-        parentThreadInfo,
-        thickThreadType,
-      ),
-      members: members.map(member =>
-        minimallyEncodeMemberInfo<ThickMemberInfo>({
-          id: member.id,
-          role: role.id,
-          permissions: membershipPermissions,
-          isSender: false,
-          subscription: defaultThreadSubscription,
-        }),
-      ),
-      roles: {
-        [role.id]: role,
-      },
-      currentUser: minimallyEncodeThreadCurrentUserInfo({
-        role: role.id,
-        permissions: membershipPermissions,
-        subscription: defaultThreadSubscription,
-        unread: false,
-      }),
-      repliesCount: 0,
-      sourceMessageID,
-      pinnedCount: 0,
-      timestamps: createThreadTimestamps(now, memberIDs),
-    };
-  } else {
-    const thinThreadType = assertThinThreadType(threadType);
-    rawThreadInfo = {
-      minimallyEncoded: true,
-      id: threadID,
-      type: thinThreadType,
-      name: name ?? null,
-      description: null,
-      color: threadColor ?? generatePendingThreadColor(memberIDs),
-      creationTime: now,
-      parentThreadID: parentThreadInfo?.id ?? null,
-      containingThreadID: getContainingThreadID(
-        parentThreadInfo,
-        thinThreadType,
-      ),
-      community: getCommunity(parentThreadInfo),
-      members: members.map(member => ({
-        id: member.id,
-        role: role.id,
-        minimallyEncoded: true,
-        isSender: false,
-      })),
-      roles: {
-        [role.id]: role,
-      },
-      currentUser: minimallyEncodeThreadCurrentUserInfo({
-        role: role.id,
-        permissions: membershipPermissions,
-        subscription: defaultThreadSubscription,
-        unread: false,
-      }),
-      repliesCount: 0,
-      sourceMessageID,
-      pinnedCount: 0,
-    };
-  }
+  const rawThreadInfo = threadSpecs[threadType].protocol.createPendingThread({
+    createPendingThreadArgs: args,
+    creationTime: now,
+    membershipPermissions,
+    role,
+    threadID,
+    memberIDs,
+  });
 
   const userInfos: { [string]: UserInfo } = {};
   for (const member of members) {
diff --git a/lib/shared/threads/protocols/dm-thread-protocol.js b/lib/shared/threads/protocols/dm-thread-protocol.js
--- a/lib/shared/threads/protocols/dm-thread-protocol.js
+++ b/lib/shared/threads/protocols/dm-thread-protocol.js
@@ -24,6 +24,11 @@
   ThickRawThreadInfo,
   MinimallyEncodedThickMemberInfo,
 } from '../../../types/minimally-encoded-thread-permissions-types.js';
+import {
+  minimallyEncodeMemberInfo,
+  minimallyEncodeThreadCurrentUserInfo,
+} from '../../../types/minimally-encoded-thread-permissions-types.js';
+import { defaultThreadSubscription } from '../../../types/subscription-types.js';
 import {
   assertThickThreadType,
   thickThreadTypes,
@@ -31,6 +36,7 @@
 import type {
   ChangeThreadSettingsPayload,
   ClientDBThreadInfo,
+  ThickMemberInfo,
 } from '../../../types/thread-types.js';
 import { threadTimestampsValidator } from '../../../types/thread-types.js';
 import { dateString as stringFromDate } from '../../../utils/date-utils.js';
@@ -39,11 +45,16 @@
   assertWithValidator,
   pendingThickSidebarURLPrefix,
 } from '../../../utils/validation-utils.js';
+import { generatePendingThreadColor } from '../../color-utils.js';
 import {
   dmOperationSpecificationTypes,
   type OutboundDMOperationSpecification,
 } from '../../dm-ops/dm-op-types.js';
 import { getIDFromLocalID } from '../../id-utils.js';
+import {
+  createThreadTimestamps,
+  getContainingThreadID,
+} from '../../thread-utils.js';
 import type {
   ProtocolSendTextMessageInput,
   SendMultimediaMessageUtils,
@@ -72,6 +83,7 @@
   ProtocolLeaveThreadInput,
   FetchMessageUtils,
   ProtocolFetchMessageInput,
+  ProtocolCreatePendingThreadInput,
 } from '../thread-spec.js';
 
 const dmThreadProtocol: ThreadProtocol<MinimallyEncodedThickMemberInfo> =
@@ -659,6 +671,62 @@
       await promise;
     },
 
+    createPendingThread: (input: ProtocolCreatePendingThreadInput) => {
+      const {
+        threadID,
+        creationTime,
+        membershipPermissions,
+        role,
+        memberIDs,
+        createPendingThreadArgs: {
+          threadType,
+          name,
+          threadColor,
+          parentThreadInfo,
+          members,
+          sourceMessageID,
+        },
+      } = input;
+      const thickThreadType = assertThickThreadType(threadType);
+      return {
+        minimallyEncoded: true,
+        thick: true,
+        id: threadID,
+        type: thickThreadType,
+        name: name ?? null,
+        description: null,
+        color: threadColor ?? generatePendingThreadColor(memberIDs),
+        creationTime,
+        parentThreadID: parentThreadInfo?.id ?? null,
+        containingThreadID: getContainingThreadID(
+          parentThreadInfo,
+          thickThreadType,
+        ),
+        members: members.map(member =>
+          minimallyEncodeMemberInfo<ThickMemberInfo>({
+            id: member.id,
+            role: role.id,
+            permissions: membershipPermissions,
+            isSender: false,
+            subscription: defaultThreadSubscription,
+          }),
+        ),
+        roles: {
+          [role.id]: role,
+        },
+        currentUser: minimallyEncodeThreadCurrentUserInfo({
+          role: role.id,
+          permissions: membershipPermissions,
+          subscription: defaultThreadSubscription,
+          unread: false,
+        }),
+        repliesCount: 0,
+        sourceMessageID,
+        pinnedCount: 0,
+        timestamps: createThreadTimestamps(creationTime, memberIDs),
+      };
+    },
+
     allowsDeletingSidebarSource: false,
 
     presentationDetails: {
diff --git a/lib/shared/threads/protocols/keyserver-thread-protocol.js b/lib/shared/threads/protocols/keyserver-thread-protocol.js
--- a/lib/shared/threads/protocols/keyserver-thread-protocol.js
+++ b/lib/shared/threads/protocols/keyserver-thread-protocol.js
@@ -44,7 +44,9 @@
   ThinRawThreadInfo,
   MemberInfoSansPermissions,
 } from '../../../types/minimally-encoded-thread-permissions-types.js';
+import { minimallyEncodeThreadCurrentUserInfo } from '../../../types/minimally-encoded-thread-permissions-types.js';
 import type { Dispatch } from '../../../types/redux-types.js';
+import { defaultThreadSubscription } from '../../../types/subscription-types.js';
 import {
   assertThinThreadType,
   thinThreadTypes,
@@ -59,7 +61,9 @@
   SendMessageError,
 } from '../../../utils/errors.js';
 import { pendingSidebarURLPrefix } from '../../../utils/validation-utils.js';
+import { generatePendingThreadColor } from '../../color-utils.js';
 import { getNextLocalID } from '../../id-utils.js';
+import { getCommunity, getContainingThreadID } from '../../thread-utils.js';
 import { identifyInvalidatedThreads } from '../../updates/utils.js';
 import type {
   ThreadProtocol,
@@ -89,6 +93,7 @@
   LeaveThreadUtils,
   FetchMessageUtils,
   ProtocolFetchMessageInput,
+  ProtocolCreatePendingThreadInput,
 } from '../thread-spec.js';
 
 const keyserverThreadProtocol: ThreadProtocol<MemberInfoSansPermissions> =
@@ -433,6 +438,58 @@
       }
     },
 
+    createPendingThread: (input: ProtocolCreatePendingThreadInput) => {
+      const {
+        threadID,
+        creationTime,
+        membershipPermissions,
+        role,
+        memberIDs,
+        createPendingThreadArgs: {
+          threadType,
+          name,
+          threadColor,
+          parentThreadInfo,
+          members,
+          sourceMessageID,
+        },
+      } = input;
+      const thinThreadType = assertThinThreadType(threadType);
+      return {
+        minimallyEncoded: true,
+        id: threadID,
+        type: thinThreadType,
+        name: name ?? null,
+        description: null,
+        color: threadColor ?? generatePendingThreadColor(memberIDs),
+        creationTime,
+        parentThreadID: parentThreadInfo?.id ?? null,
+        containingThreadID: getContainingThreadID(
+          parentThreadInfo,
+          thinThreadType,
+        ),
+        community: getCommunity(parentThreadInfo),
+        members: members.map(member => ({
+          id: member.id,
+          role: role.id,
+          minimallyEncoded: true,
+          isSender: false,
+        })),
+        roles: {
+          [role.id]: role,
+        },
+        currentUser: minimallyEncodeThreadCurrentUserInfo({
+          role: role.id,
+          permissions: membershipPermissions,
+          subscription: defaultThreadSubscription,
+          unread: false,
+        }),
+        repliesCount: 0,
+        sourceMessageID,
+        pinnedCount: 0,
+      };
+    },
+
     allowsDeletingSidebarSource: true,
 
     presentationDetails: {
diff --git a/lib/shared/threads/thread-spec.js b/lib/shared/threads/thread-spec.js
--- a/lib/shared/threads/thread-spec.js
+++ b/lib/shared/threads/thread-spec.js
@@ -62,6 +62,7 @@
   SubscriptionUpdateRequest,
   SubscriptionUpdateResult,
 } from '../../types/subscription-types.js';
+import type { ThreadPermissionsInfo } from '../../types/thread-permission-types.js';
 import type { ThreadType } from '../../types/thread-types-enum.js';
 import type {
   ChangeThreadSettingsPayload,
@@ -75,6 +76,7 @@
   OutboundDMOperationSpecification,
 } from '../dm-ops/dm-op-types.js';
 import type { FetchThickMessagesType } from '../message-utils.js';
+import type { CreatePendingThreadArgs } from '../thread-utils.js';
 
 export type ThreadTrait =
   | 'sidebar'
@@ -228,6 +230,15 @@
   +dispatchActionPromise: DispatchActionPromise,
 };
 
+export type ProtocolCreatePendingThreadInput = {
+  +createPendingThreadArgs: CreatePendingThreadArgs,
+  +creationTime: number,
+  +membershipPermissions: ThreadPermissionsInfo,
+  +role: RoleInfo,
+  +threadID: string,
+  +memberIDs: $ReadOnlyArray<string>,
+};
+
 export type ThreadProtocol<
   RawThreadMemberType:
     | MemberInfoSansPermissions
@@ -296,6 +307,9 @@
     input: ProtocolFetchMessageInput,
     utils: FetchMessageUtils,
   ) => Promise<void>,
+  +createPendingThread: (
+    input: ProtocolCreatePendingThreadInput,
+  ) => RawThreadInfo,
   +allowsDeletingSidebarSource: boolean,
   +presentationDetails: {
     +membershipChangesShownInThreadPreview: boolean,