diff --git a/lib/shared/sidebar-utils.js b/lib/shared/sidebar-utils.js
--- a/lib/shared/sidebar-utils.js
+++ b/lib/shared/sidebar-utils.js
@@ -22,7 +22,6 @@
 } from '../types/message-types.js';
 import type { ThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
 import { threadPermissions } from '../types/thread-permission-types.js';
-import { threadTypes, threadTypeIsThick } from '../types/thread-types-enum.js';
 import type { LoggedInUserInfo } from '../types/user-types.js';
 import type { GetENSNames } from '../utils/ens-helpers.js';
 import {
@@ -105,9 +104,9 @@
 
   return createPendingThread({
     viewerID,
-    threadType: threadTypeIsThick(parentThreadInfo.type)
-      ? threadTypes.THICK_SIDEBAR
-      : threadTypes.SIDEBAR,
+    threadType:
+      threadSpecs[parentThreadInfo.type].protocol.sidebarConfig
+        .sidebarThreadType,
     members: [...initialMembers.values()],
     parentThreadInfo,
     threadColor: color,
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
@@ -13,6 +13,7 @@
 import { extractUserMentionsFromText } from './mention-utils.js';
 import { relationshipBlockedInEitherDirection } from './relationship-utils.js';
 import type { SidebarItem } from './sidebar-item-utils.js';
+import { protocols } from './threads/protocols/thread-protocols.js';
 import {
   threadSpecs,
   threadTypeIsCommunityRoot,
@@ -414,10 +415,10 @@
   sourceMessageID: ?string,
 ): string {
   let pendingThreadKey;
-  if (sourceMessageID && threadTypeIsThick(threadType)) {
-    pendingThreadKey = `${pendingThickSidebarURLPrefix}/${sourceMessageID}`;
-  } else if (sourceMessageID) {
-    pendingThreadKey = `${pendingSidebarURLPrefix}/${sourceMessageID}`;
+  if (sourceMessageID) {
+    const prefix =
+      threadSpecs[threadType].protocol.sidebarConfig.pendingSidebarURLPrefix;
+    pendingThreadKey = `${prefix}/${sourceMessageID}`;
   } else {
     pendingThreadKey = [...memberIDs].sort().join('+');
   }
@@ -442,18 +443,13 @@
   }
 
   const [threadTypeString, threadKey] = pendingThreadIDMatches[1].split('/');
-  let threadType;
-  if (threadTypeString === pendingThickSidebarURLPrefix) {
-    threadType = threadTypes.THICK_SIDEBAR;
-  } else if (threadTypeString === pendingSidebarURLPrefix) {
-    threadType = threadTypes.SIDEBAR;
-  } else {
-    threadType = assertThreadType(Number(threadTypeString.replace('type', '')));
-  }
+  const threadType =
+    protocols.find(
+      p => p.sidebarConfig.pendingSidebarURLPrefix === threadTypeString,
+    )?.sidebarConfig.sidebarThreadType ??
+    assertThreadType(Number(threadTypeString.replace('type', '')));
 
-  const threadTypeStringIsSidebar =
-    threadTypeString === pendingSidebarURLPrefix ||
-    threadTypeString === pendingThickSidebarURLPrefix;
+  const threadTypeStringIsSidebar = threadTypeIsSidebar(threadType);
   const memberIDs = threadTypeStringIsSidebar ? [] : threadKey.split('+');
   const sourceMessageID = threadTypeStringIsSidebar ? threadKey : null;
   return {
@@ -1601,9 +1597,8 @@
     return threadInfo;
   }
   members.push(...mentionedNewMembers);
-  const threadType = threadTypeIsThick(parentThreadInfo.type)
-    ? threadTypes.THICK_SIDEBAR
-    : threadTypes.SIDEBAR;
+  const threadType =
+    threadSpecs[parentThreadInfo.type].protocol.sidebarConfig.sidebarThreadType;
 
   return createPendingThread({
     viewerID,
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
@@ -18,6 +18,7 @@
 import type { ChangeThreadSettingsPayload } from '../../../types/thread-types.js';
 import { dateString as stringFromDate } from '../../../utils/date-utils.js';
 import { SendMessageError } from '../../../utils/errors.js';
+import { pendingThickSidebarURLPrefix } from '../../../utils/validation-utils.js';
 import {
   dmOperationSpecificationTypes,
   type OutboundDMOperationSpecification,
@@ -490,6 +491,11 @@
   uploadMultimediaToKeyserver: false,
 
   canActionsTargetPendingMessages: true,
+
+  sidebarConfig: {
+    sidebarThreadType: thickThreadTypes.THICK_SIDEBAR,
+    pendingSidebarURLPrefix: pendingThickSidebarURLPrefix,
+  },
 });
 
 export { dmThreadProtocol };
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
@@ -34,6 +34,7 @@
 import { getMediaMessageServerDBContentsFromMedia } from '../../../types/messages/media.js';
 import type { RawReactionMessageInfo } from '../../../types/messages/reaction.js';
 import type { Dispatch } from '../../../types/redux-types.js';
+import { thinThreadTypes } from '../../../types/thread-types-enum.js';
 import {
   blobHashFromBlobServiceURI,
   isBlobServiceURI,
@@ -42,6 +43,7 @@
   getMessageForException,
   SendMessageError,
 } from '../../../utils/errors.js';
+import { pendingSidebarURLPrefix } from '../../../utils/validation-utils.js';
 import { getNextLocalID } from '../../id-utils.js';
 import type {
   ThreadProtocol,
@@ -327,6 +329,11 @@
   uploadMultimediaToKeyserver: true,
 
   canActionsTargetPendingMessages: false,
+
+  sidebarConfig: {
+    sidebarThreadType: thinThreadTypes.SIDEBAR,
+    pendingSidebarURLPrefix: pendingSidebarURLPrefix,
+  },
 });
 
 function mediaIDIsKeyserverID(mediaID: string): boolean {
diff --git a/lib/shared/threads/protocols/thread-protocols.js b/lib/shared/threads/protocols/thread-protocols.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/protocols/thread-protocols.js
@@ -0,0 +1,8 @@
+// @flow
+
+import { dmThreadProtocol } from './dm-thread-protocol.js';
+import { keyserverThreadProtocol } from './keyserver-thread-protocol.js';
+
+const protocols = [dmThreadProtocol, keyserverThreadProtocol];
+
+export { protocols };
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
@@ -46,6 +46,7 @@
   ThreadInfo,
 } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { Dispatch } from '../../types/redux-types.js';
+import type { ThreadType } from '../../types/thread-types-enum.js';
 import type {
   ChangeThreadSettingsPayload,
   UpdateThreadRequest,
@@ -232,6 +233,10 @@
   },
   +uploadMultimediaToKeyserver: boolean,
   +canActionsTargetPendingMessages: boolean,
+  +sidebarConfig: {
+    +sidebarThreadType: ThreadType,
+    +pendingSidebarURLPrefix: string,
+  },
 };
 
 export type ThreadSpec = {