diff --git a/lib/ops/entries-store-ops.js b/lib/ops/entries-store-ops.js
--- a/lib/ops/entries-store-ops.js
+++ b/lib/ops/entries-store-ops.js
@@ -1,6 +1,13 @@
 // @flow
 
-import type { RawEntryInfo } from '../types/entry-types.js';
+import type { BaseStoreOpsHandlers } from './base-ops.js';
+import { daysToEntriesFromEntryInfos } from '../reducers/entry-reducer.js';
+import type {
+  EntryStore,
+  RawEntryInfo,
+  RawEntryInfos,
+} from '../types/entry-types.js';
+import { values } from '../utils/objects.js';
 
 export type ReplaceEntryOperation = {
   +type: 'replace_entry',
@@ -26,7 +33,7 @@
 
 export type ClientDBEntryInfo = {
   +id: string,
-  +entryInfo: string,
+  +entry: string,
 };
 
 export type ClientDBReplaceEntryOperation = {
@@ -38,3 +45,91 @@
   | ClientDBReplaceEntryOperation
   | RemoveEntriesOperation
   | RemoveAllEntriesOperation;
+
+function convertEntryInfoIntoClientDBEntryInfo({
+  id,
+  entry,
+}: {
+  +id: string,
+  +entry: RawEntryInfo,
+}): ClientDBEntryInfo {
+  return {
+    id,
+    entry: JSON.stringify(entry),
+  };
+}
+
+const entryStoreOpsHandlers: BaseStoreOpsHandlers<
+  EntryStore,
+  EntryStoreOperation,
+  ClientDBEntryStoreOperation,
+  RawEntryInfos,
+  ClientDBEntryInfo,
+> = {
+  processStoreOperations(
+    entryStore: EntryStore,
+    ops: $ReadOnlyArray<EntryStoreOperation>,
+  ): EntryStore {
+    if (ops.length === 0) {
+      return entryStore;
+    }
+
+    const processedEntryStore = {
+      ...entryStore,
+    };
+    for (const operation of ops) {
+      if (operation.type === 'replace_entry') {
+        processedEntryStore.entryInfos = {
+          ...processedEntryStore.entryInfos,
+          [operation.payload.id]: operation.payload.entry,
+        };
+      } else if (operation.type === 'remove_entries') {
+        const idsToRemove = new Set(operation.payload.ids);
+        processedEntryStore.entryInfos = Object.fromEntries(
+          Object.entries(processedEntryStore.entryInfos).filter(
+            ([id]) => !idsToRemove.has(id),
+          ),
+        );
+      } else if (operation.type === 'remove_all_entries') {
+        processedEntryStore.entryInfos = {};
+      }
+    }
+
+    console.log(JSON.stringify(processedEntryStore, null, 2));
+    processedEntryStore.daysToEntries = daysToEntriesFromEntryInfos(
+      values(processedEntryStore.entryInfos),
+    );
+
+    return processedEntryStore;
+  },
+
+  convertOpsToClientDBOps(
+    ops: ?$ReadOnlyArray<EntryStoreOperation>,
+  ): $ReadOnlyArray<ClientDBEntryStoreOperation> {
+    if (!ops) {
+      return [];
+    }
+    return ops.map(operation => {
+      if (
+        operation.type === 'remove_entries' ||
+        operation.type === 'remove_all_entries'
+      ) {
+        return operation;
+      }
+      return {
+        type: 'replace_entry',
+        payload: convertEntryInfoIntoClientDBEntryInfo(operation.payload),
+      };
+    });
+  },
+
+  translateClientDBData(
+    clientDBEntries: $ReadOnlyArray<ClientDBEntryInfo>,
+  ): RawEntryInfos {
+    return Object.fromEntries(
+      clientDBEntries.map(({ id, entry }) => [id, JSON.parse(entry)]),
+    );
+  },
+};
+
+export { convertEntryInfoIntoClientDBEntryInfo, entryStoreOpsHandlers };
diff --git a/lib/ops/entries-store-ops.test.js b/lib/ops/entries-store-ops.test.js
new file mode 100644
--- /dev/null
+++ b/lib/ops/entries-store-ops.test.js
@@ -0,0 +1,170 @@
+// @flow
+
+import { entryStoreOpsHandlers } from './entries-store-ops.js';
+
+const entryStore = {
+  entryInfos: {
+    'A3F2E633-320D-4CDC-A0A7-48325A07E321|87868': {
+      id: 'A3F2E633-320D-4CDC-A0A7-48325A07E321|87868',
+      threadID: 'A3F2E633-320D-4CDC-A0A7-48325A07E321|87695',
+      text: 'aaa',
+      year: 2024,
+      month: 5,
+      day: 21,
+      creationTime: 1716287287704,
+      creatorID: 'ACDC8087-8540-4C97-A0AB-B1A0254C4405',
+      deleted: false,
+    },
+    'localb59fc932-56c2-4ada-9179-36f5f0cb4855': {
+      localID: 'localb59fc932-56c2-4ada-9179-36f5f0cb4855',
+      threadID: 'A3F2E633-320D-4CDC-A0A7-48325A07E321|87695',
+      text: '',
+      year: 2024,
+      month: 5,
+      day: 22,
+      creationTime: 1716287380610,
+      creatorID: 'ACDC8087-8540-4C97-A0AB-B1A0254C4405',
+      deleted: false,
+    },
+  },
+  daysToEntries: {
+    '2024-05-21': ['A3F2E633-320D-4CDC-A0A7-48325A07E321|87868'],
+    '2024-05-22': ['localb59fc932-56c2-4ada-9179-36f5f0cb4855'],
+  },
+  lastUserInteractionCalendar: 1716287380611,
+};
+
+describe('entryStoreOpsHandlers', () => {
+  describe('processStoreOperations', () => {
+    it('should process replace operation', () => {
+      const newEntry = {
+        id: '123',
+        threadID: 'A3F2E633-320D-4CDC-A0A7-48325A07E321|87695',
+        text: 'aaa',
+        year: 2024,
+        month: 5,
+        day: 22,
+        creationTime: 1716287287704,
+        creatorID: 'ACDC8087-8540-4C97-A0AB-B1A0254C4405',
+        deleted: false,
+      };
+      expect(
+        entryStoreOpsHandlers.processStoreOperations(entryStore, [
+          {
+            type: 'replace_entry',
+            payload: {
+              id: '123',
+              entry: newEntry,
+            },
+          },
+        ]),
+      ).toEqual({
+        entryInfos: {
+          ...entryStore.entryInfos,
+          ['123']: newEntry,
+        },
+        daysToEntries: {
+          ...entryStore.daysToEntries,
+          '2024-05-22': ['123', 'localb59fc932-56c2-4ada-9179-36f5f0cb4855'],
+        },
+        lastUserInteractionCalendar: 1716287380611,
+      });
+    });
+
+    it('should process remove operation', () => {
+      expect(
+        entryStoreOpsHandlers.processStoreOperations(entryStore, [
+          {
+            type: 'remove_entries',
+            payload: {
+              ids: ['localb59fc932-56c2-4ada-9179-36f5f0cb4855'],
+            },
+          },
+        ]),
+      ).toEqual({
+        entryInfos: {
+          ['A3F2E633-320D-4CDC-A0A7-48325A07E321|87868']:
+            entryStore.entryInfos['A3F2E633-320D-4CDC-A0A7-48325A07E321|87868'],
+        },
+        daysToEntries: {
+          '2024-05-21': ['A3F2E633-320D-4CDC-A0A7-48325A07E321|87868'],
+        },
+        lastUserInteractionCalendar: 1716287380611,
+      });
+    });
+
+    it('should process remove all operation', () => {
+      expect(
+        entryStoreOpsHandlers.processStoreOperations(entryStore, [
+          {
+            type: 'remove_all_entries',
+          },
+        ]),
+      ).toEqual({
+        entryInfos: {},
+        daysToEntries: {},
+        lastUserInteractionCalendar: 1716287380611,
+      });
+    });
+  });
+
+  describe('convertOpsToClientDBOps', () => {
+    it('should not modify remove entries operation', () => {
+      const operation = {
+        type: 'remove_entries',
+        payload: { ids: ['1', '2', '3'] },
+      };
+      expect(
+        entryStoreOpsHandlers.convertOpsToClientDBOps([operation]),
+      ).toEqual([operation]);
+    });
+
+    it('should not modify remove all entries operations', () => {
+      const operation = {
+        type: 'remove_all_entries',
+      };
+      expect(
+        entryStoreOpsHandlers.convertOpsToClientDBOps([operation]),
+      ).toEqual([operation]);
+    });
+
+    it('should modify replace entry operation', () => {
+      const key = 'localb59fc932-56c2-4ada-9179-36f5f0cb4855';
+      const operation = {
+        type: 'replace_entry',
+        payload: {
+          id: key,
+          entry: entryStore.entryInfos[key],
+        },
+      };
+      expect(
+        entryStoreOpsHandlers.convertOpsToClientDBOps([operation]),
+      ).toEqual([
+        {
+          type: 'replace_entry',
+          payload: {
+            id: key,
+            entry: JSON.stringify(entryStore.entryInfos[key]),
+          },
+        },
+      ]);
+    });
+  });
+
+  describe('translateClientDBData', () => {
+    it('should convert client DB entries', () => {
+      const key = 'A3F2E633-320D-4CDC-A0A7-48325A07E321|87868';
+      const clientDBEntries = [
+        {
+          id: key,
+          entry: JSON.stringify(entryStore.entryInfos[key]),
+        },
+      ];
+      const translated =
+        entryStoreOpsHandlers.translateClientDBData(clientDBEntries);
+      expect(translated).toEqual({
+        [key]: entryStore.entryInfos[key],
+      });
+    });
+  });
+});