From 9355b030a2c5d1082fcbc03b801d3cc02fa40d47 Mon Sep 17 00:00:00 2001
From: Li-Chieh Kung <lichieh@patagoniahealth.net>
Date: Tue, 22 Sep 2026 13:06:47 -0400
Subject: [PATCH] Handle Postgres pool errors instead of crashing

An idle client disconnected by a database restart or failover makes
pg.Pool emit `error`; with no listener, Node throws and the API and
worker processes exit. Register a listener that logs via
backgroundFailure (error name only, no connection details).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
---
 apps/server/src/db.ts     | 10 +++++++++-
 tests/persistence.test.ts | 13 ++++++++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/apps/server/src/db.ts b/apps/server/src/db.ts
index a40c9a2a7..290753221 100644
--- a/apps/server/src/db.ts
+++ b/apps/server/src/db.ts
@@ -2,6 +2,7 @@ import { mkdir } from "node:fs/promises";
 import { dirname } from "node:path";
 import { PGlite } from "@electric-sql/pglite";
 import pg from "pg";
+import { backgroundFailure } from "./log.ts";
 
 type Row = { data: Record<string, unknown> };
 interface Database {
@@ -111,12 +112,19 @@ export class Store {
   }
 }
 
+/** Idle clients can be disconnected by a database restart; without a listener pg's `error` event crashes the process. */
+export function createPool(connectionString: string) {
+  const pool = new pg.Pool({ connectionString, max: 5 });
+  pool.on("error", (error) => backgroundFailure("postgres pool", error));
+  return pool;
+}
+
 export async function createStore(
   options: { dataDir?: string; databaseUrl?: string } = {},
 ): Promise<Store> {
   let database: Database;
   if (options.databaseUrl) {
-    const pool = new pg.Pool({ connectionString: options.databaseUrl, max: 5 });
+    const pool = createPool(options.databaseUrl);
     database = { query: async (sql, params) => pool.query(sql, params), close: () => pool.end() };
   } else {
     if (options.dataDir) await mkdir(dirname(options.dataDir), { recursive: true, mode: 0o700 });
diff --git a/tests/persistence.test.ts b/tests/persistence.test.ts
index 73eaac487..e371655cb 100644
--- a/tests/persistence.test.ts
+++ b/tests/persistence.test.ts
@@ -3,7 +3,7 @@ import { mkdtemp, rm } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { test } from "node:test";
-import { createStore } from "../apps/server/src/db.ts";
+import { createPool, createStore } from "../apps/server/src/db.ts";
 
 test("fresh nested data directory starts and survives a database restart", async () => {
   const root = await mkdtemp(join(tmpdir(), "openmuse-db-"));
@@ -20,3 +20,14 @@ test("fresh nested data directory starts and survives a database restart", async
     await rm(root, { recursive: true, force: true });
   }
 });
+
+test("idle Postgres client errors are logged instead of crashing the process", async (t) => {
+  const logged = t.mock.method(console, "error", () => {});
+  const pool = createPool("postgres://127.0.0.1:1/openmuse");
+  try {
+    assert.doesNotThrow(() => pool.emit("error", new Error("terminating connection")));
+    assert.equal(logged.mock.callCount(), 1);
+  } finally {
+    await pool.end();
+  }
+});