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
@@ -1344,8 +1344,10 @@
   return !!defaultRole.permissions[threadPermissions.VOICED];
 }
 
+const draftKeySuffix = '/message_composer';
+
 function draftKeyFromThreadID(threadID: string): string {
-  return `${threadID}/message_composer`;
+  return `${threadID}${draftKeySuffix}`;
 }
 
 function getContainingThreadID(
@@ -1636,6 +1638,7 @@
   useCanCreateSidebarFromMessage,
   useSidebarExistsOrCanBeCreated,
   checkIfDefaultMembersAreVoiced,
+  draftKeySuffix,
   draftKeyFromThreadID,
   threadTypeCanBePending,
   getContainingThreadID,
diff --git a/lib/utils/migration-utils.js b/lib/utils/migration-utils.js
new file mode 100644
--- /dev/null
+++ b/lib/utils/migration-utils.js
@@ -0,0 +1,68 @@
+// @flow
+
+import { entries } from './objects.js';
+import { keyserverPrefixID } from './validation-utils.js';
+import {
+  parsePendingThreadID,
+  getPendingThreadID,
+  draftKeySuffix,
+} from '../shared/thread-utils.js';
+import type {
+  ClientDBDraftInfo,
+  ClientDBDraftStoreOperation,
+  DraftStore,
+} from '../types/draft-types';
+
+function convertDraftKeyToNewIDSchema(key: string): string {
+  const threadID = key.slice(0, -draftKeySuffix.length);
+
+  const pendingIDContents = parsePendingThreadID(threadID);
+
+  if (!pendingIDContents) {
+    return `${keyserverPrefixID}|${key}`;
+  }
+
+  const { threadType, sourceMessageID, memberIDs } = pendingIDContents;
+
+  if (!sourceMessageID) {
+    return key;
+  }
+
+  const convertedThreadID = getPendingThreadID(
+    threadType,
+    memberIDs,
+    `${keyserverPrefixID}|${sourceMessageID}`,
+  );
+
+  return `${convertedThreadID}${draftKeySuffix}`;
+}
+
+function convertDraftStoreToNewIDSchema(store: DraftStore): DraftStore {
+  return {
+    drafts: Object.fromEntries(
+      entries(store.drafts).map(([key, value]) => [
+        convertDraftKeyToNewIDSchema(key),
+        value,
+      ]),
+    ),
+  };
+}
+
+function generateIDSchemaMigrationOpsForDrafts(
+  drafts: $ReadOnlyArray<ClientDBDraftInfo>,
+): $ReadOnlyArray<ClientDBDraftStoreOperation> {
+  const operations = drafts.map(draft => ({
+    type: 'update',
+    payload: {
+      key: convertDraftKeyToNewIDSchema(draft.key),
+      text: draft.text,
+    },
+  }));
+  return [{ type: 'remove_all' }, ...operations];
+}
+
+export {
+  convertDraftKeyToNewIDSchema,
+  convertDraftStoreToNewIDSchema,
+  generateIDSchemaMigrationOpsForDrafts,
+};
diff --git a/lib/utils/migration-utils.test.js b/lib/utils/migration-utils.test.js
new file mode 100644
--- /dev/null
+++ b/lib/utils/migration-utils.test.js
@@ -0,0 +1,87 @@
+// @flow
+
+import {
+  convertDraftKeyToNewIDSchema,
+  convertDraftStoreToNewIDSchema,
+  generateIDSchemaMigrationOpsForDrafts,
+} from './migration-utils.js';
+import type {
+  ClientDBDraftInfo,
+  ClientDBDraftStoreOperation,
+  DraftStore,
+} from '../types/draft-types.js';
+
+describe('id schema migrations', () => {
+  it('should convert draft keys', () => {
+    const examples = [
+      ['123/message_composer', '256|123/message_composer'],
+      [
+        'pending/sidebar/83874/message_composer',
+        'pending/sidebar/256|83874/message_composer',
+      ],
+      [
+        'pending/type6/83811+84104/message_composer',
+        'pending/type6/83811+84104/message_composer',
+      ],
+    ];
+
+    for (const [before, after] of examples) {
+      expect(convertDraftKeyToNewIDSchema(before)).toEqual(after);
+    }
+  });
+
+  it('should convert draft store', () => {
+    const exampleDraftStore: DraftStore = {
+      drafts: {
+        '83818/message_composer': 'draft',
+        'pending/sidebar/83874/message_composer': 'draft',
+        'pending/type6/83811+84104/message_composer': 'draft',
+      },
+    };
+    const convertedDraftStore: DraftStore = {
+      drafts: {
+        '256|83818/message_composer': 'draft',
+        'pending/sidebar/256|83874/message_composer': 'draft',
+        'pending/type6/83811+84104/message_composer': 'draft',
+      },
+    };
+
+    expect(convertDraftStoreToNewIDSchema(exampleDraftStore)).toEqual(
+      convertedDraftStore,
+    );
+  });
+
+  it('should generate migration ops for drafts', () => {
+    const drafts: $ReadOnlyArray<ClientDBDraftInfo> = [
+      { key: '83818/message_composer', text: 'draft' },
+      { key: 'pending/sidebar/83874/message_composer', text: 'draft' },
+      { key: 'pending/type6/83811+84104/message_composer', text: 'draft' },
+    ];
+    const operations: $ReadOnlyArray<ClientDBDraftStoreOperation> = [
+      { type: 'remove_all' },
+      {
+        payload: {
+          key: '256|83818/message_composer',
+          text: 'draft',
+        },
+        type: 'update',
+      },
+      {
+        payload: {
+          key: 'pending/sidebar/256|83874/message_composer',
+          text: 'draft',
+        },
+        type: 'update',
+      },
+      {
+        payload: {
+          key: 'pending/type6/83811+84104/message_composer',
+          text: 'draft',
+        },
+        type: 'update',
+      },
+    ];
+
+    expect(generateIDSchemaMigrationOpsForDrafts(drafts)).toEqual(operations);
+  });
+});