fix(db/postgres): handle idle pool client errors

Author: dcoric

src/db/postgres/helper.ts

@@ -32,6 +32,12 @@ const ensurePool = (): Pool => {
   }
 
   _pool = new Pool({ connectionString });
+  // An idle client in the pool can emit 'error' (e.g. the backend dropped the
+  // connection). Without a listener node treats this as an uncaught exception
+  // and crashes the process; log it instead and let the pool recycle the client.
+  _pool.on('error', (err) => {
+    console.error('Postgres pool error on idle client:', err);
+  });
   return _pool;
 };
 

test/db/postgres/helper.test.ts

@@ -19,6 +19,7 @@ import { describe, it, expect, beforeEach, vi } from 'vitest';
 const mockPoolQuery = vi.fn();
 const mockPoolEnd = vi.fn();
 const mockPoolCtor = vi.fn();
+const mockPoolOn = vi.fn();
 
 vi.mock('pg', () => {
   class Pool {
@@ -27,6 +28,7 @@ vi.mock('pg', () => {
     }
     query = mockPoolQuery;
     end = mockPoolEnd;
+    on = mockPoolOn;
   }
   return { Pool };
 });
@@ -114,6 +116,28 @@ describe('PostgreSQL - helper', async () => {
     });
   });
 
+  describe('pool error handling', () => {
+    it('registers an idle-client error listener that logs without crashing', async () => {
+      getDatabaseMock.mockReturnValue({
+        type: 'postgres',
+        enabled: true,
+        connectionString: 'postgresql://localhost/x',
+      });
+      const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => undefined);
+
+      await connect();
+
+      const errorRegistration = mockPoolOn.mock.calls.find((call) => call[0] === 'error');
+      expect(errorRegistration).toBeDefined();
+
+      const handler = errorRegistration![1] as (err: Error) => void;
+      expect(() => handler(new Error('connection terminated unexpectedly'))).not.toThrow();
+      expect(errorSpy).toHaveBeenCalled();
+
+      errorSpy.mockRestore();
+    });
+  });
+
   describe('getSessionStore', () => {
     it('throws when connection string is missing — no MemoryStore fallback', () => {
       getDatabaseMock.mockReturnValue({