Show HN: Kuron – An LLM acts as your app so you can try ideas before building

Write an idea in one line — even one that would take ~50 hours to build. Within about a minute it is running on minimal screens and you can use it by hand, so you can find out whether it is worth building. Nothing is generated per idea: the LLM sets the system up, then is the system on every action.

one line ─▶ setup agent (LLM + tools) ─▶ brief · data · screens · timers · checks · reality estimate │ button / timer / camera / mic ─▶ event agent (LLM + tools) ─▶ reads what it needs, changes the world, │ speaks, plays sound, draws "this should…" ─▶ request agent ─▶ changes its own brief, screens, data, checks │ world.json ◀────┘ ─▶ minimal face: website, phone, desktop, IoT panel, watch…

The code is only a set of generic tools exposed over MCP — store and read data, define a screen, notify, look through the camera, listen to the mic, play and shape sound, speak, draw, set timers — plus a minimal renderer. Every tool checks the shape of its input and answers in words; the LLM corrects itself. There is no business logic, no word list, no per-idea exception in the code.

When a prototype behaves wrongly, you don’t patch it: you tell it how it should behave (“urgent patients go first”), and the request agent rewrites its own brief, screens and checks.

One English idea file for a small clinic: reception tablet, doctor’s PC, stock PC, patient’s phone and waiting-room display. Claude set it up from the idea in 65 s with 16 tool calls (about $0.41), then acted as the system on every button. Each reply below is what it actually did; only the waiting time between steps is shortened.