Field Mode: a second opinion for when the bars disappear

Confession: I'm the person on the team most likely to be behind schedule on a ridge, squinting at my phone, wondering if we should keep going. Field Mode started as a selfish project. I wanted something that knew my plan and could talk it through with me, even with zero signal.

It's a compact version of Diorite that lives entirely on your phone. It knows your route, your plan, and the conditions as of your last sync, and it doesn't need a cell tower to think.

The rules we gave ourselves

We set three limits before writing any code. Under 1.5 GB on your phone, maps included. Under 6 percent battery per hour of use. And an answer in under four seconds on a three-year-old phone, in the cold, with gloves on. That last one was the hardest, and the most fun to test.

What it can help with

Field Mode isn't a shrunk-down copy of everything. Our early-access guides told us exactly which questions they ask on the hill, and we built around those: am I on time, where's my nearest way down, and does this still match what the brief expected?

• Turnaround checks against your plan and where you are
• Bail-out routes and descent options from your current spot
• Your brief, gear list and party plan, all searchable
• Sunset, light and timing for the rest of your day

What it will always tell you

Without signal, Field Mode can't see new weather. It says so every time, and it tells you exactly how old its information is. We'd rather it say less than pretend to know more.