Disposable certification page — not a production artifact.
Purpose: obtain one Embedded Signup authorization code via the documented FB.login() JavaScript-SDK mechanism (not the Meta Builder / /dialog/oauth mechanism), to test against the existing, unmodified MetaTokenExchangeService C1 shape.
The authorization code is never displayed on screen or written to the browser console. Use the "Copy code" button to copy it directly to the clipboard, then paste it immediately into the isolated /opt/stacks/eswap-v26-cert test invocation — it expires in 30 seconds. Take this page down after the test; do not leave it live.