Five concrete situations.

Lattice isn't useful for everyone. It's specifically useful for these five situations. If you don't recognise yourself in any of them, you probably don't need it. If you do, install it now while everything is calm.

1. You and your family during a regional internet shutdown.

Iran. Myanmar. Sudan. Belarus. Some governments switch the internet off — sometimes for hours, sometimes for weeks. WhatsApp, Signal, iMessage, all of them go quiet. Lattice doesn't, because Lattice doesn't use the internet to deliver messages.

What it can do: keep you in touch with family members in your city, hopping through other Lattice users between you. That's enough to confirm everyone is okay, agree on a meeting place, share a piece of news.

What it can't do: reach a relative in another city, unless someone with a phone carries the message between cities, or the optional LoRa hardware is in play, or the internet comes back. Why physics says so.

2. You and friends at a festival or event.

Glastonbury, a stadium gig, a packed New Year's Eve. Every cell tower in the area is at capacity. Texts don't go through. Group voice calls disconnect. WhatsApp loads two-day-old messages because the data link is choking.

Lattice likes dense crowds. The more nearby phones running it, the better the routing works. There's a coarse "where's my friend?" feature that uses the same mesh: each phone broadcasts its rough location every few minutes, only to its verified contacts. You can suggest a meeting point — Lattice computes the centroid of the group and drops a pin everyone can see.

3. You and your kids during a disaster.

Earthquake, hurricane, wildfire, flood. The towers are down. The power's out. You don't know if the kids made it home from school. Lattice on their phone, Lattice on yours, both of you have a few minutes of battery — that's a working messenger.

The check-in feature was built for this exact situation. Once a month it nudges you to send a "still here?" message to your two-to-five most important people, so you know the lines work before the day you need them.

4. You and someone in a country where messengers are blocked.

Journalists. Family of dissidents. Activists. Researchers fielding sources in restrictive regimes. The standard Western messengers are sometimes blocked outright, sometimes monitored, sometimes still working but visibly so — and that visibility itself can be dangerous.

Lattice is honest about what it does and doesn't help with here. It does encrypt the contents of your messages with end-to-end + post-quantum cryptography, leaving nothing readable for an observer. It does not hide the fact that you are running Lattice — the radios are detectable to anyone in range. For high-threat use, see the threat model in WP-01 and the limits in WP-05.

5. You as a parent or partner who just wants to be ready.

You don't think you need it. You don't expect a disaster. But you'd rather have it installed than not, the same way you keep a torch in a drawer.

This is the case for installing prophylactically. Lattice is designed to cost you almost nothing while it waits. After a week without use, it slips into a low-power "Standby" mode. After a month, it goes "Dormant" and barely scans at all. The whole point is that it shouldn't drain your battery while you don't need it. How dormancy works.

Once a month, it'll nudge you to send a one-tap test message to your important people, so the lines stay warm. That's the whole maintenance burden.

What if you're not in any of these situations?

Then Lattice is probably not for you. We are not building a daily-driver messenger. WhatsApp and Signal are excellent for that. Lattice is the standby tool — a piece of safety equipment for the day normal communication doesn't work.

If you only ever use Lattice once, the day you use it, it will have been worth installing.