From 2d36ae63263c69ab79fc2a912c67741334578040 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Sat, 13 Dec 2025 15:16:42 +0000
Subject: [PATCH] fix(browser): derive cdp port from control url

---
 src/browser/config.test.ts | 8 ++++++++
 src/browser/config.ts      | 8 ++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/browser/config.test.ts b/src/browser/config.test.ts
index 1c64cc7d6..9dc83d19f 100644
--- a/src/browser/config.test.ts
+++ b/src/browser/config.test.ts
@@ -38,6 +38,14 @@ describe("browser config", () => {
     expect(shouldStartLocalBrowserServer(resolved)).toBe(false);
   });
 
+  it("derives CDP port as control port + 1", () => {
+    const resolved = resolveBrowserConfig({
+      controlUrl: "http://127.0.0.1:19000",
+    });
+    expect(resolved.controlPort).toBe(19000);
+    expect(resolved.cdpPort).toBe(19001);
+  });
+
   it("rejects unsupported protocols", () => {
     expect(() =>
       resolveBrowserConfig({ controlUrl: "ws://127.0.0.1:18790" }),
diff --git a/src/browser/config.ts b/src/browser/config.ts
index 9307c3278..f8182de45 100644
--- a/src/browser/config.ts
+++ b/src/browser/config.ts
@@ -1,6 +1,5 @@
 import type { BrowserConfig } from "../config/config.js";
 import {
-  DEFAULT_CLAWD_BROWSER_CDP_PORT,
   DEFAULT_CLAWD_BROWSER_COLOR,
   DEFAULT_CLAWD_BROWSER_CONTROL_URL,
   DEFAULT_CLAWD_BROWSER_ENABLED,
@@ -55,7 +54,12 @@ export function resolveBrowserConfig(
     throw new Error(`browser.controlUrl has invalid port: ${parsed.port}`);
   }
 
-  const cdpPort = DEFAULT_CLAWD_BROWSER_CDP_PORT;
+  const cdpPort = port + 1;
+  if (cdpPort > 65535) {
+    throw new Error(
+      `browser.controlUrl port (${port}) is too high; cannot derive CDP port (${cdpPort})`,
+    );
+  }
   if (port === cdpPort) {
     throw new Error(
       `browser.controlUrl port (${port}) must not equal CDP port (${cdpPort})`,