From ac1180326bfdff4d3e89285467a543e1e3e6ba6d Mon Sep 17 00:00:00 2001
From: pedrofrxncx <pedro_vaz_franca@hotmail.com>
Date: Fri, 24 Jul 2026 15:18:53 -0300
Subject: [PATCH] fix(settings): treat bracketed IPv6 loopback
 DATABASE_URL/NATS_URL as local

---
 apps/api/src/settings/resolve-config.test.ts | 28 ++++++++++++++++++++
 apps/api/src/settings/resolve-config.ts      |  4 ++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/apps/api/src/settings/resolve-config.test.ts b/apps/api/src/settings/resolve-config.test.ts
index 22e300e49b..f26a75c486 100644
--- a/apps/api/src/settings/resolve-config.test.ts
+++ b/apps/api/src/settings/resolve-config.test.ts
@@ -218,6 +218,34 @@ describe("resolveConfig Studio environment aliases", () => {
   });
 });
 
+describe("resolveConfig external database/nats URL detection", () => {
+  it("treats a bracketed IPv6 loopback DATABASE_URL as local, not external", () => {
+    const result = resolveConfig(flags, {
+      DATABASE_URL: "postgres://[::1]:5432/postgres",
+    });
+
+    expect(result.externalDatabaseUrl).toBeNull();
+  });
+
+  it("treats a bracketed IPv6 loopback NATS_URL as local, not external", () => {
+    const result = resolveConfig(flags, {
+      NATS_URL: "nats://[::1]:4222",
+    });
+
+    expect(result.externalNatsUrl).toBeNull();
+  });
+
+  it("still treats a genuinely remote host as external", () => {
+    const result = resolveConfig(flags, {
+      DATABASE_URL: "postgres://db.example.com:5432/postgres",
+    });
+
+    expect(result.externalDatabaseUrl).toBe(
+      "postgres://db.example.com:5432/postgres",
+    );
+  });
+});
+
 describe("resolveConfig NODE_ENV", () => {
   it("defaults to development when unset", () => {
     const result = resolveConfig(flags, {});
diff --git a/apps/api/src/settings/resolve-config.ts b/apps/api/src/settings/resolve-config.ts
index c0d8b2909f..6c9fc0c3b4 100644
--- a/apps/api/src/settings/resolve-config.ts
+++ b/apps/api/src/settings/resolve-config.ts
@@ -123,7 +123,9 @@ function externalUrlOrNull(url: string | undefined): string | null {
   if (!url) return null;
   try {
     const parsed = new URL(url);
-    const host = parsed.hostname;
+    // `URL#hostname` keeps the brackets for a bracketed IPv6 host (e.g.
+    // "[::1]"), so strip them before comparing against the bare loopback form.
+    const host = parsed.hostname.replace(/^\[|\]$/g, "");
     if (host === "localhost" || host === "127.0.0.1" || host === "::1") {
       return null;
     }