diff --git a/packages/shared/src/chat/index.ts b/packages/shared/src/chat/index.ts
index cb04224..2172065 100644
--- a/packages/shared/src/chat/index.ts
+++ b/packages/shared/src/chat/index.ts
@@ -7,6 +7,7 @@ export * from './groups';
 export * from './messages';
 export * from './types';
 export * from './userKeyMigration';
+export * from './pinnedMessages';
 
 // ----- RPC wrappers ---------------------------------------------------------
 
diff --git a/packages/shared/src/chat/pinnedMessages.test.ts b/packages/shared/src/chat/pinnedMessages.test.ts
new file mode 100644
index 0000000..fa25c79
--- /dev/null
+++ b/packages/shared/src/chat/pinnedMessages.test.ts
@@ -0,0 +1,61 @@
+import { describe, expect, it } from 'vitest';
+
+import { listPinnedMessages, pinMessage, unpinMessage } from './pinnedMessages';
+
+function fakeClient(rows: Array<Record<string, unknown>>) {
+  const calls: Array<{ name: string; payload: unknown }> = [];
+  const client = {
+    from(_table: string) {
+      return {
+        select: () => ({
+          eq: () => ({
+            order: () => Promise.resolve({ data: rows, error: null }),
+          }),
+        }),
+        insert: (payload: unknown) => {
+          calls.push({ name: 'insert', payload });
+          return Promise.resolve({ error: null });
+        },
+        delete: () => ({
+          eq: () => ({
+            eq: () => {
+              calls.push({ name: 'delete', payload: null });
+              return Promise.resolve({ error: null });
+            },
+          }),
+        }),
+      };
+    },
+  };
+  return { client, calls };
+}
+
+describe('pinnedMessages', () => {
+  it('listPinnedMessages maps DB rows to camelCase', async () => {
+    const rows = [
+      { conversation_id: 'c1', message_id: 'm1', pinned_by: 'u1', pinned_at: '2026-05-16T10:00:00Z' },
+    ];
+    const { client } = fakeClient(rows);
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    const result = await listPinnedMessages(client as any, 'c1');
+    expect(result).toEqual([
+      { conversationId: 'c1', messageId: 'm1', pinnedBy: 'u1', pinnedAt: '2026-05-16T10:00:00Z' },
+    ]);
+  });
+
+  it('pinMessage inserts with the right shape', async () => {
+    const { client, calls } = fakeClient([]);
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    await pinMessage(client as any, 'c1', 'm1', 'u1');
+    expect(calls).toEqual([
+      { name: 'insert', payload: { conversation_id: 'c1', message_id: 'm1', pinned_by: 'u1' } },
+    ]);
+  });
+
+  it('unpinMessage deletes by conversation_id + message_id', async () => {
+    const { client, calls } = fakeClient([]);
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    await unpinMessage(client as any, 'c1', 'm1');
+    expect(calls).toEqual([{ name: 'delete', payload: null }]);
+  });
+});
diff --git a/packages/shared/src/chat/pinnedMessages.ts b/packages/shared/src/chat/pinnedMessages.ts
new file mode 100644
index 0000000..139d047
--- /dev/null
+++ b/packages/shared/src/chat/pinnedMessages.ts
@@ -0,0 +1,65 @@
+import type { AppSupabaseClient } from '../supabase/client';
+
+export interface PinnedMessage {
+  conversationId: string;
+  messageId: string;
+  pinnedBy: string;
+  pinnedAt: string;
+}
+
+interface Row {
+  conversation_id: string;
+  message_id: string;
+  pinned_by: string;
+  pinned_at: string;
+}
+
+function mapRow(r: Row): PinnedMessage {
+  return {
+    conversationId: r.conversation_id,
+    messageId: r.message_id,
+    pinnedBy: r.pinned_by,
+    pinnedAt: r.pinned_at,
+  };
+}
+
+export async function listPinnedMessages(
+  client: AppSupabaseClient,
+  conversationId: string,
+): Promise<PinnedMessage[]> {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const { data, error } = await (client as any)
+    .from('pinned_messages')
+    .select('conversation_id, message_id, pinned_by, pinned_at')
+    .eq('conversation_id', conversationId)
+    .order('pinned_at', { ascending: false });
+  if (error) throw error;
+  return (data ?? []).map(mapRow);
+}
+
+export async function pinMessage(
+  client: AppSupabaseClient,
+  conversationId: string,
+  messageId: string,
+  pinnedBy: string,
+): Promise<void> {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const { error } = await (client as any)
+    .from('pinned_messages')
+    .insert({ conversation_id: conversationId, message_id: messageId, pinned_by: pinnedBy });
+  if (error) throw error;
+}
+
+export async function unpinMessage(
+  client: AppSupabaseClient,
+  conversationId: string,
+  messageId: string,
+): Promise<void> {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const { error } = await (client as any)
+    .from('pinned_messages')
+    .delete()
+    .eq('conversation_id', conversationId)
+    .eq('message_id', messageId);
+  if (error) throw error;
+}