agent-browser

Agent Browser

Use agent-browser for local Open Design preview validation: inspect rendered state, click/type when requested, and capture one screenshot when visual evidence matters. Keep the browser local-first unless the user explicitly asks for external browsing.

Requirements

Verify the CLI before doing any browser work:

command -v agent-browser

If missing, stop and tell the user to install it:

npm i -g agent-browser
agent-browser install

Do not replace the CLI with ad hoc browser scripts.

Context Hygiene

Never print full upstream guides into chat or tool output. Save them to temp files and extract only task-relevant lines:

AGENT_BROWSER_CORE="${TMPDIR:-/tmp}/agent-browser-core.$$.md"
agent-browser skills get core > "$AGENT_BROWSER_CORE"
rg -n "cdp|connect|snapshot|screenshot|click|type|wait|get title|get url" "$AGENT_BROWSER_CORE"

Use agent-browser skills get core --full only when needed, and redirect it to a temp file the same way.

CDP Startup Contract

agent-browser must attach to an existing CDP endpoint. Never run agent-browser open before agent-browser connect; doing so can make the CLI auto-launch Chrome and re-enter the crash path.

Use this sequence:

if ! curl -fsS http://127.0.0.1:9223/json/version | rg -q webSocketDebuggerUrl; then
  open -na "Google Chrome" --args \
    --remote-debugging-port=9223 \
    --user-data-dir=/tmp/od-agent-browser-chrome \
    --no-first-run \
    --no-default-browser-check

  for i in {1..20}; do
    if curl -fsS http://127.0.0.1:9223/json/version | rg -q webSocketDebuggerUrl; then
      break
    fi
    sleep 0.5
  done
fi

curl -fsS http://127.0.0.1:9223/json/version | rg webSocketDebuggerUrl
agent-browser connect http://127.0.0.1:9223

If CDP is still unavailable after polling, stop and ask the user to launch Chrome manually from Terminal:

/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome \
  --remote-debugging-port=9223 \
  --user-data-dir=/tmp/od-agent-browser-chrome \
  --no-first-run \
  --no-default-browser-check