One-time setup for a persistent debug browser on `127.0.0.1:9222` for `dev-browser --connect`. Use when browser work is needed but no reusable debug browser is running yet.
Use this skill when dev-browser --connect http://127.0.0.1:9222 fails because
no persistent debug browser is running yet.
Get the user onto one persistent browser/profile that both the human and the
agent reuse. Minimize the Allow remote debugging? popup by keeping one
dedicated debug browser/profile alive.
--user-data-dir as mandatory, not optional. Chrome 136+
basically wants remote debugging to happen from a dedicated profile.dev. Do not
use the user's normal daily Default profile as the source profile.--user-data-dir; do not point 9222 straight at the user's daily Chrome
data dir.open -na "Google Chrome" --args ... for the debug browser.
That starts a separate Chrome instance with the dedicated debug profile
without touching the user's normal Chrome window.Use a dedicated browser/profile with:
--remote-debugging-address=127.0.0.1--remote-debugging-port=9222--user-data-dir=<debug-profile-dir>Sign in once in that dedicated browser and keep reusing it for agent work.
Quick sanity check:
curl -sS http://127.0.0.1:9222/json/version
Healthy output includes a JSON object with webSocketDebuggerUrl. Empty output
or 404 means the wrong process owns 9222.
Then verify dev-browser:
dev-browser --connect http://127.0.0.1:9222 <<'EOF'
const page = await browser.getPage("persistent-main");
console.log(await page.title());
EOF
If dev-browser --connect http://127.0.0.1:9222 still cannot resolve CDP even
though /json/version is healthy, connect with the exact websocket URL:
WS=$(curl -sS http://127.0.0.1:9222/json/version | jq -r '.webSocketDebuggerUrl')
dev-browser --connect "$WS" <<'EOF'
const page = await browser.getPage("persistent-main");
console.log(await page.title());
EOF
Default setup on macOS:
dev, not
the daily Default profile.Local State.9222.python3 - <<'PY'
import json, pathlib
p = pathlib.Path('~/Library/Application Support/Google/Chrome/Local State').expanduser()
obj = json.loads(p.read_text())
for key, val in obj.get('profile', {}).get('info_cache', {}).items():
print(f"{key}\tname={val.get('name')}\tgaia_name={val.get('gaia_name')}")
PY
# Example: if `dev` maps to `Profile 1`, clone `Profile 1`.
mkdir -p "$HOME/.config/google-chrome-debug-profile/Default"
rsync -a --delete \
--exclude='Singleton*' \
--exclude='DevToolsActivePort' \
--exclude='lockfile' \
"$HOME/Library/Application Support/Google/Chrome/Profile 1/" \
"$HOME/.config/google-chrome-debug-profile/Default/"
cp "$HOME/Library/Application Support/Google/Chrome/Local State" \
"$HOME/.config/google-chrome-debug-profile/Local State"
open -na "Google Chrome" --args \
--user-data-dir="$HOME/.config/google-chrome-debug-profile" \
--profile-directory="Default" \
--remote-debugging-address=127.0.0.1 \
--remote-debugging-port=9222
That keeps the signed-in identity while still satisfying Chrome's dedicated
--user-data-dir requirement.
Then keep reusing that exact debug browser. Do not point 9222 at your normal
daily Default Chrome profile.
dev-browser --connect http://127.0.0.1:9222 for browser work.persistent-main.9222, identify it with lsof -nP -iTCP:9222 -sTCP:LISTEN,
kill that listener, and relaunch the dedicated debug browser. Do not keep
debugging against a stale 404 or empty /json/version owner.