Case study01 / GRANITE

Granite

An engine that reasons — not a plan you follow.

ServicesNative · Agentic · On-device

Sitegranite.coach ↗

RoleDesign + build

StatusAlpha

Year2026

Granite — the training week the engine builds — The week the engine builds — on-device

The work
01 / GRANITE

Granite is a strength coach that runs entirely on your phone. Not a plan you follow, but an engine that reasons — building your training around the life you actually train through, rewriting it each week as things change. We built it deterministic and on-device on purpose: your training history never leaves your hands, and every decision it makes can be traced, tested, and trusted.

The problem

A plan you cannot follow is worth nothing.

The week movesLife firstWork, sleep, travel, a niggle. The week you planned is rarely the week you get.

So the plan breaksMiss twoFixed programmes have no answer for a missed session, so people improvise or stop.

And nobody explainsNo reasonApps change your numbers without saying why, so there is nothing to trust or argue with.

One mechanism underneath all three: training adapts to the person, or the person quietly stops training.

Granite — the weekly rewrite, with the reasoning shown

Fig. 01 · Granite · the weekly rewriteYou missed sessions, so it pulls the week back — a deload, 40% less volume, loads held — and traces exactly what changed and why.

1For the person training

You do not need more discipline, you need a week that survives contact with your life. Granite rewrites it and tells you what changed.

2For the people who prescribe

Coaches and clinicians cannot stand behind a black box that will not show its reasoning. A deterministic engine can be inspected, tested and argued with.

A coach, not a plan

Most training apps hand you a fixed plan and hope you follow it. Granite works the other way round. It reasons — taking your goals, your experience, the days you actually have, your injuries, and the load you carry off the platform — and builds a week that fits your real life.

When something changes, it rewrites, and tells you why. Not a plan you obey. A coach that adapts.

Granite — telling the coach what changed this week — You say this

Granite — the same week after the note: bench press cut to 80kg and two shoulder-prehab movements added — The plan changes

Fig. 02 · Granite · say this, the plan changesOne sentence: two BJJ sessions a week, and a sore left shoulder. On the right is the same week afterwards — bench press cut from 95 kg to 80, Face Pull swapped out, and Band Pull-apart and External Rotation added to both days. Nothing was re-entered, and every change traces back to that sentence.

The engine is the product

The intelligence in Granite is deterministic, not generative — and that’s a deliberate choice, not a limitation. It means every plan is consistent, every decision can be traced, and the whole system can be tested against real coaching principles rather than hoping a black box got it right.

Accountable intelligence beats impressive intelligence when it’s your body on the line. We built the engine first, and everything else serves it.

Granite — a session in progress, with the reason for today and pain capture

Fig. 03 · Granite · the sessionEvery session opens with why it exists today — then prescribes load and RPE per set, and takes a pain flag inline, because that is the input that changes next week.

On-device by decision

Granite runs entirely on your phone. No account, no cloud, no data leaving your hands — the privacy isn’t a policy you have to trust, it’s the architecture. Running locally was the harder path, and it made the product sharper: an engine that can’t lean on the cloud has to be deliberate about every decision.

That constraint is the craft. Granite is the considered version of something most people build the easy way.

Granite — progress and personal records, tracked on-device

Fig. 04 · Granite · on-device historyEvery session, every PR and every trend lives on the phone — no account, no cloud, nothing leaving your hands.

Art direction

Made before the app existed.

Concept film · not product footage

The ledger · kept / cut

The product is the decisions we refused to skip.

+Kept

A deterministic engine you can trace
On-device — no account, no cloud
A weekly rewrite that explains itself

−Cut

A generative black box guessing your plan
Cloud sync and sign-in
Streaks, badges, a feed to scroll

One we killed

We almost shipped cloud sync in week three — it would have made onboarding one tap and the demo look cleaner. We killed it because the moment your training history touches our servers, “on-device and accountable” stops being an architecture and becomes a marketing line. The harder path was the product.

Scope. What is public here is the consumer app. The engine underneath it was built to serve more than one reader — and those surfaces stay off the site until they ship. The architecture is the asset; publishing how it decides is not.

StackSwift · SwiftUI · on-device

Timeline2026

ConstraintNo cloud. No account. No black box.

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