Where exactly do I set a hard daily loss limit?

That distinction is exactly right and it's the one worth insisting on. Risk limits live in the risk layer of order settings, separate from your strategy logic — that separation is deliberate, so that a limit isn't something a strategy edit can quietly remove. Set it there and it applies across whatever strategies are running. We'd suggest setting it as an absolute amount rather than a percentage you'd have to recompute, and setting it before the session rather than during.

The separation is the part I appreciate. A limit you can edit while inside a losing trade isn't a limit.

Dumb question maybe — does the limit count realized losses only, or does an open position moving against you push you over it too? I've never been sure which one I'm actually setting.

Both. It checks today's realised P/L plus the unrealised on anything you are still holding, measured against your equity base. Realised-only sounds tidier but it fails the case the limit exists for: a position sitting deep underwater that you never close would never trip it. And when it does trip, it flattens and stops the session rather than just blocking new entries.

Does it reset on your local midnight or the exchange's? Matters a lot for crypto.

I once set one of these and then "temporarily" raised it on a bad afternoon because I was sure the trade was about to come back. It did not come back. So yeah, the version you can't click through is the one you want, I'm proof.

Neither. It is Eastern midnight. Fixed to ET rather than your machine clock so the boundary does not move if you travel, and fixed to a calendar day rather than a session so that on crypto "daily" does not quietly turn into "since I started the app".

Two things I'd add from doing it the tedious way: check what happens to positions you already have open when the limit trips (does it just block new orders or does it flatten you), and test it with a tiny limit on a quiet day so you actually see the behaviour once before it matters. Knowing exactly what the stop looks like takes a lot of the panic out of it.