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CricCuts Blog · How it's built

Build with a genius.
Ship a machine.

The cleverest thing about CricCuts is something you'll never run. We use LLM-powered agentic development to build, test and endlessly refine a complex, deterministic engine — the kind of software that used to need a whole team and a year of tuning. What lands on your phone is cheap, instant, accurate, and structurally incapable of hallucinating.

⏱ ~7 min read 🛠 How it's built 🤖 Agentic dev

There are two very different ways to put artificial intelligence into an app. The obvious one is to call a large language model every single time the app runs — the pattern behind most "AI apps" you've met. The other is quieter, and often far better: use the AI while you build, and ship something that doesn't need it at all.

Two places an AI can live

Where you put the intelligence changes everything about the product that comes out the other end. It can sit at runtime, thinking on every use — or at development time, doing its thinking once, in the workshop, so the shipped app never has to.

🤖 An AI at runtime

  • A big model runs on every single use
  • Costs money per request — forever
  • Usually needs the cloud; useless offline
  • Adds round-trip latency to every answer
  • Can hallucinate — confidently invent things
  • Hard to test: same input, different output

🛠 An AI at development time

  • Helps you design, write, test and tune the app
  • What ships is plain, deterministic code + a few tiny models
  • Free to run — no model to pay for on each use
  • Instant & offline — nothing to phone home to
  • Can't make things up — no improviser in the loop
  • Reproducible — same input, same output, testable

CricCuts is built entirely the second way. The intelligence went into building the tools — not into running them.

The kind of app that used to be too hard to build

Some apps are, underneath, a big pile of judgement — "is this the moment that matters?" You can't capture that in one clean rule. It's dozens of interacting signals and thresholds, each nudging the others, all of them needing to be tuned against messy, real-world data that never behaves like the demo.

Historically, that made this whole class of app brutal to build. You needed rare expertise — signal processing, audio, computer vision — and then a punishing loop: run on real footage, stare at every false alarm and every miss, form a theory, nudge a parameter, re-run, and pray you didn't quietly break three other things. Each turn of that loop could eat a day. The space of possible settings is combinatorial; a small team could ever only explore a sliver of it. So these apps were the preserve of big, well-funded teams — or they simply never got made.

The hard part was never having the idea. It was the ten thousand tiny, tedious, interacting adjustments between the idea and something that actually works.

What changed: an agent in the loop

Agentic development flips the economics of that loop. An AI agent can hold the whole pipeline in its head at once — every signal, every threshold, every place a change ripples outward — and reason about a tweak the way a veteran engineer would. Crucially, it also builds the measuring instruments: evaluation harnesses, scoreboards against a human-labelled "golden" set, side-by-side A/B runs, contact sheets of every mistake it made. Then it proposes a change, runs the experiment, reads the results, and goes again — dozens of times over, tirelessly, in the time a person would manage a single pass.

The upshot is that one person can now develop, test and iterate software that used to demand a room full of specialists. Not by making the app cleverer at runtime — by making the building of it dramatically faster, cheaper and more rigorous.

The agentic development loop feeding a shipped deterministic engine At development time, an agent runs the deterministic tools on real footage, scores the output against a human-labelled ground truth, proposes a fix, and refines the tools — a loop that repeats. Only the hardened, deterministic engine crosses into runtime and ships to the phone. DEVELOPMENT TIME RUNTIME AGENTIC LOOP 1 Run it for real genuine footage 2 Score vs truth hits & misses 3 Agent finds why and writes the test 4 Refine the tools keep what wins harden & ship WHAT SHIPS A deterministic engine Instant — real-time on-device Free — no per-use cost Private — offline, on your phone Reproducible — same in, same out Can't hallucinate — nothing improvised no large model runs here
Real footage runs through the deterministic engine; its output is scored against a human-labelled ground truth; the agent proposes and tests a fix; the tools are refined — round after round. Only the hardened engine ever crosses into runtime and ships.

The loop, one turn at a time

Strip away the jargon and each turn of the loop is four honest steps:

  1. Run it on real footage. The deterministic tools make their pass over genuine recordings — the messy, real-world kind, not a tidy demo clip.
  2. Score it against human truth. Every result is checked against a hand-labelled "golden" set of what a person would actually pick. Two numbers matter: what it missed, and what it flagged by mistake.
  3. Let the agent find the why. It reads the whole pipeline, forms a hypothesis about the cause of a miss or a false alarm, and writes the experiment that will test it.
  4. Refine, re-run, keep what wins. The change goes in, the full benchmark re-runs, and it survives only if it genuinely improves the score without quietly breaking something else. Then the loop turns again.

Nothing here is magic, and nothing here hallucinates — every step is checked against reality. Over hundreds of turns, that discipline compounds into an engine that's genuinely good at a very hard, very specific job.

🧠
The intelligence goes into the tool, not the runtime. By the time the app is in your hand, the cleverness has been baked into plain, fast, predictable code — so it runs for free, offline, in the few seconds after you tap analyse, and gives the same answer every time.

Why ship determinism at all?

Because once the hard thinking is done, a deterministic engine quietly wins on everything that matters to the person actually using the app:

Free to run

No per-request bill on every use, so the app can stay genuinely free.

Instant

No round-trip to a server — results in seconds, even on a five-year-old phone.

Private & offline

Your footage is analysed on the device and never has to be uploaded.

Trustworthy

Same input, same output — so it can be tested, and it can't invent a moment that never happened.

An LLM-at-runtime app struggles to promise any of these. Agentic development gets you the sophistication of modern AI baked into the artefact, without carrying the cost, latency, privacy and reliability liabilities of running a giant model on every single use.

The opportunity: a whole class of apps just opened up

This isn't only about cricket. The same recipe — an agent in the workshop, a cheap deterministic core in the product — unlocks a category of software that used to be uneconomical for small teams to even attempt:

In each case the durable advantage isn't a model you rent by the token — it's the accumulated judgement, encoded in deterministic tools, tests and benchmarks that cost almost nothing to run and can't be reproduced by prompting a chatbot. The AI helped build it; the moat is what got built.

CricCuts is our proof that this works in the wild — a genuinely hard video-understanding problem, solved on a phone, for free, built by one person with an agent in the loop. The genius did its work in the workshop. What you hold is the machine it made.

See the machine the workshop made

Intelligent, on-device cricket highlights — free, private, offline, and built the agentic way. Point it at your footage and watch it work.

Get the app → How it works

Related reading: the companion piece — the idea the AI missed, on the one breakthrough no model suggested — plus why the future of AI is small models on the edge and why it might be many small models working together. For the plain-English walkthrough of what the engine actually does, see how a phone watches cricket and cuts the highlights itself. More on the CricCuts blog.

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