On Windows (and some Linux setups), an application like VS Code's
js-debug can hold 127.0.0.1:9222 while a Chromium browser launched
with --remote-debugging-port=9222 silently binds [::1]:9222 only.
The IPv4-only probe then (a) missed the live browser entirely and
(b) hung against the squatter — which accepts TCP but never answers
the /json/version HTTP probe — repeatedly, driving the whole connect
past the desktop GUI's RPC deadline:
'error: request timed out: browser.manage'.
Fix, applied to both the gateway browser.manage RPC and the CLI
/browser connect path via shared helpers in browser_connect.py:
- discover_local_cdp_url(): probe BOTH loopbacks (127.0.0.1 first,
then [::1]) and adopt whichever actually speaks CDP.
- local_port_in_use() + find_free_debug_port(): when neither loopback
speaks CDP but the port is held by another application, report the
squatter explicitly and launch the debug browser on a nearby free
port instead of fighting a bind conflict on 9222.
- Bound the gateway's post-launch wait to a 10s deadline (was up to
20 unbounded probe cycles) so connect always answers inside the
client RPC timeout.
- _wait_for_browser_debug_ready_or_exit() also probes dual-stack so a
successful launch pushed onto [::1] is classified 'ready'.
Verified on a live Windows repro (VS Code holding 127.0.0.1:9222,
Chrome 148 on [::1]:9222): connect now resolves http://[::1]:9222
in ~4.5s instead of timing out.
