From 96f12d8428912f3ac81f4207c5b58343a537562c Mon Sep 17 00:00:00 2001
From: Siddarth Chalasani <siddarth@runloop.ai>
Date: Tue, 24 Mar 2026 15:20:56 -0700
Subject: [PATCH 1/2] extract tunnel domain from base url

---
 src/sdk/devbox.ts                              |  4 +++-
 tests/objects/devbox.test.ts                   | 18 ++++++++++++++++++
 .../smoketests/object-oriented/devbox.test.ts  |  4 ++--
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/sdk/devbox.ts b/src/sdk/devbox.ts
index df25963c9..a338b423e 100644
--- a/src/sdk/devbox.ts
+++ b/src/sdk/devbox.ts
@@ -838,7 +838,9 @@ export class Devbox {
     if (!tunnel) {
       throw new RunloopError('No tunnel has been enabled for this devbox. Call net.enableTunnel() first.');
     }
-    return `https://${port}-${tunnel.tunnel_key}.tunnel.runloop.ai`;
+    const apiHost = new URL(this.client.baseURL).hostname;
+    const baseDomain = apiHost.split('.').slice(-2).join('.');
+    return `https://${port}-${tunnel.tunnel_key}.tunnel.${baseDomain}`;
   }
 
   /**
diff --git a/tests/objects/devbox.test.ts b/tests/objects/devbox.test.ts
index 4a9fadfa9..94a9d6739 100644
--- a/tests/objects/devbox.test.ts
+++ b/tests/objects/devbox.test.ts
@@ -11,6 +11,7 @@ describe('Devbox (New API)', () => {
   beforeEach(() => {
     // Create mock client instance with proper structure
     mockClient = {
+      baseURL: 'https://api.runloop.ai',
       devboxes: {
         createAndAwaitRunning: jest.fn(),
         retrieve: jest.fn(),
@@ -303,6 +304,23 @@ describe('Devbox (New API)', () => {
         expect(url).toBe('https://3000-mykey456.tunnel.runloop.ai');
       });
 
+      it('should derive tunnel domain from client baseURL', async () => {
+        mockClient.baseURL = 'https://api.runloop.pro';
+        const mockTunnel = {
+          tunnel_key: 'abc123xyz',
+          auth_mode: 'open' as const,
+          create_time_ms: Date.now(),
+        };
+        const dataWithTunnel = { ...mockDevboxData, tunnel: mockTunnel };
+        mockClient.devboxes.retrieve.mockResolvedValue(dataWithTunnel);
+
+        const url = await devbox.getTunnelUrl(8080);
+
+        expect(url).toBe('https://8080-abc123xyz.tunnel.runloop.pro');
+
+        mockClient.baseURL = 'https://api.runloop.ai';
+      });
+
       it('should throw RunloopError when no tunnel has been enabled', async () => {
         const dataWithoutTunnel = { ...mockDevboxData, tunnel: null };
         mockClient.devboxes.retrieve.mockResolvedValue(dataWithoutTunnel);
diff --git a/tests/smoketests/object-oriented/devbox.test.ts b/tests/smoketests/object-oriented/devbox.test.ts
index 603128f30..8d8598cbd 100644
--- a/tests/smoketests/object-oriented/devbox.test.ts
+++ b/tests/smoketests/object-oriented/devbox.test.ts
@@ -413,10 +413,10 @@ describe('smoketest: object-oriented devbox', () => {
         expect(tunnel.tunnel_key).toBeTruthy();
 
         const url = await devbox.getTunnelUrl(8080);
-        expect(url).toBe(`https://8080-${tunnel.tunnel_key}.tunnel.runloop.ai`);
+        expect(url).toContain(`https://8080-${tunnel.tunnel_key}.tunnel.runloop.`);
 
         const url3000 = await devbox.getTunnelUrl(3000);
-        expect(url3000).toBe(`https://3000-${tunnel.tunnel_key}.tunnel.runloop.ai`);
+        expect(url3000).toContain(`https://3000-${tunnel.tunnel_key}.tunnel.runloop.`);
       } finally {
         await devbox.shutdown();
       }

From 775c494e8d28d3641271baa08837f52d6c7a8165 Mon Sep 17 00:00:00 2001
From: Siddarth Chalasani <siddarth@runloop.ai>
Date: Tue, 24 Mar 2026 15:33:49 -0700
Subject: [PATCH 2/2] address comments

---
 src/sdk/devbox.ts            | 2 +-
 tests/objects/devbox.test.ts | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/sdk/devbox.ts b/src/sdk/devbox.ts
index a338b423e..e34a938d3 100644
--- a/src/sdk/devbox.ts
+++ b/src/sdk/devbox.ts
@@ -839,7 +839,7 @@ export class Devbox {
       throw new RunloopError('No tunnel has been enabled for this devbox. Call net.enableTunnel() first.');
     }
     const apiHost = new URL(this.client.baseURL).hostname;
-    const baseDomain = apiHost.split('.').slice(-2).join('.');
+    const baseDomain = apiHost.startsWith('api.') ? apiHost.slice(4) : apiHost;
     return `https://${port}-${tunnel.tunnel_key}.tunnel.${baseDomain}`;
   }
 
diff --git a/tests/objects/devbox.test.ts b/tests/objects/devbox.test.ts
index 94a9d6739..2cb930c97 100644
--- a/tests/objects/devbox.test.ts
+++ b/tests/objects/devbox.test.ts
@@ -305,7 +305,6 @@ describe('Devbox (New API)', () => {
       });
 
       it('should derive tunnel domain from client baseURL', async () => {
-        mockClient.baseURL = 'https://api.runloop.pro';
         const mockTunnel = {
           tunnel_key: 'abc123xyz',
           auth_mode: 'open' as const,
@@ -314,9 +313,11 @@ describe('Devbox (New API)', () => {
         const dataWithTunnel = { ...mockDevboxData, tunnel: mockTunnel };
         mockClient.devboxes.retrieve.mockResolvedValue(dataWithTunnel);
 
-        const url = await devbox.getTunnelUrl(8080);
+        mockClient.baseURL = 'https://api.runloop.pro';
+        expect(await devbox.getTunnelUrl(8080)).toBe('https://8080-abc123xyz.tunnel.runloop.pro');
 
-        expect(url).toBe('https://8080-abc123xyz.tunnel.runloop.pro');
+        mockClient.baseURL = 'http://127.0.0.1:8080';
+        expect(await devbox.getTunnelUrl(8080)).toBe('https://8080-abc123xyz.tunnel.127.0.0.1');
 
         mockClient.baseURL = 'https://api.runloop.ai';
       });