diff --git a/lib/reducers/draft-reducer.js b/lib/reducers/draft-reducer.js
new file mode 100644
--- /dev/null
+++ b/lib/reducers/draft-reducer.js
@@ -0,0 +1,77 @@
+// @flow
+
+import {
+  moveDraftActionType,
+  setDraftStoreDrafts,
+  updateDraftActionType,
+} from '../actions/draft-actions';
+import type { DraftStore, DraftStoreOperation } from '../types/draft-types';
+import type { BaseAction } from '../types/redux-types';
+
+type ReduceDraftStoreResult = {
+  +draftStoreOperations: $ReadOnlyArray<DraftStoreOperation>,
+  +draftStore: DraftStore,
+};
+function reduceDraftStore(
+  draftStore: DraftStore,
+  action: BaseAction,
+): ReduceDraftStoreResult {
+  if (action.type === updateDraftActionType) {
+    const key = action.payload.key;
+    const text = action.payload.text;
+
+    const draftStoreOperations = [
+      {
+        type: 'update',
+        payload: { key: key, text: text },
+      },
+    ];
+    return {
+      draftStoreOperations,
+      draftStore: {
+        ...draftStore,
+        drafts: {
+          ...draftStore.drafts,
+          [key]: text,
+        },
+      },
+    };
+  } else if (action.type === moveDraftActionType) {
+    const oldKey = action.payload.oldKey;
+    const newKey = action.payload.newKey;
+
+    const draftStoreOperations = [
+      {
+        type: 'move',
+        payload: { oldKey: oldKey, newKey: newKey },
+      },
+    ];
+
+    const { [oldKey]: text, ...draftsWithoutOldKey } = draftStore.drafts;
+    return {
+      draftStoreOperations,
+      draftStore: {
+        ...draftStore,
+        drafts: {
+          ...draftsWithoutOldKey,
+          [newKey]: text,
+        },
+      },
+    };
+  } else if (action.type === setDraftStoreDrafts) {
+    const drafts = {};
+    for (const dbDraftInfo of action.payload) {
+      drafts[dbDraftInfo.key] = dbDraftInfo.text;
+    }
+    return {
+      draftStoreOperations: [],
+      draftStore: {
+        ...draftStore,
+        drafts: drafts,
+      },
+    };
+  }
+  return { draftStore, draftStoreOperations: [] };
+}
+
+export { reduceDraftStore };
diff --git a/lib/reducers/master-reducer.js b/lib/reducers/master-reducer.js
--- a/lib/reducers/master-reducer.js
+++ b/lib/reducers/master-reducer.js
@@ -11,6 +11,7 @@
 import reduceCalendarFilters from './calendar-filters-reducer';
 import reduceConnectionInfo from './connection-reducer';
 import reduceDataLoaded from './data-loaded-reducer';
+import { reduceDraftStore } from './draft-reducer';
 import reduceEnabledApps from './enabled-apps-reducer';
 import { reduceEntryInfos } from './entry-reducer';
 import reduceLifecycleState from './lifecycle-state-reducer';
@@ -75,10 +76,16 @@
     }
   }
 
+  const { draftStore, draftStoreOperations } = reduceDraftStore(
+    state.draftStore,
+    action,
+  );
+
   return {
     state: {
       ...state,
       navInfo: reduceBaseNavInfo(state.navInfo, action),
+      draftStore,
       entryStore,
       loadingStatuses: reduceLoadingStatuses(state.loadingStatuses, action),
       currentUserInfo: reduceCurrentUserInfo(state.currentUserInfo, action),
@@ -100,6 +107,7 @@
       dataLoaded: reduceDataLoaded(state.dataLoaded, action),
     },
     storeOperations: {
+      draftStoreOperations,
       threadStoreOperations,
       messageStoreOperations,
     },
diff --git a/lib/types/store-ops-types.js b/lib/types/store-ops-types.js
--- a/lib/types/store-ops-types.js
+++ b/lib/types/store-ops-types.js
@@ -1,8 +1,11 @@
 // @flow
+
+import type { DraftStoreOperation } from './draft-types';
 import type { MessageStoreOperation } from './message-types';
 import type { ThreadStoreOperation } from './thread-types';
 
 export type StoreOperations = {
+  +draftStoreOperations: $ReadOnlyArray<DraftStoreOperation>,
   +threadStoreOperations: $ReadOnlyArray<ThreadStoreOperation>,
   +messageStoreOperations: $ReadOnlyArray<MessageStoreOperation>,
 };