Ask the user to hand this session a Zeno API key. Use this first — every current Zeno user already has an account.

email is the address on their Zeno account. Ask them for it; you cannot guess it, and the request is aimed by it — Zeno will only show it to somebody signed in as the owner of that address. Pass client_name too: it is the only thing identifying you on the approval page, and without it the person is asked to trust "an unnamed client".

Returns a plain verification_uri. Tell the user to open it, sign in, and approve the request waiting there; we also email them a notice. There is no code, in either direction: nothing to read out, nothing to type, and nothing for you to put in a link.

Then call collect_api_key with the claim_token returned here, waiting poll_interval_seconds between calls, until its status stops being pending. The user chooses on the page what the key may reach — usually a single company — so expect the key to be scoped, and read a 403 elsewhere as that scope rather than as a failure.

The answer is the same whether or not that address has a Zeno account. If nothing ever arrives, the likeliest cause is a mistyped address — ask, do not assume.