This is the original way to run Prototo, kept for terminal pros. Prototo Desktop is the recommended flow now; everything below still works.

The same product runs as two Terminal windows and the iOS Simulator.

Window 1 — Prototo

npx proto start

This starts Prototo and opens the iOS Simulator. Leave this window running. You never type in it again.

Window 2: your coding agent

cd myapp
claude   # or: codex

This is the design tool. Everything you describe here appears in the Simulator.

Your agent reads DESIGN.md before every generation, so it already knows your colours, typography, spacing, and component library. You never repeat context.

The complete terminal workflow

npx proto start      → Simulator opens       (Window 1, leave it)
cd myapp && claude   → your agent opens      (Window 2, stay here)
describe a screen    → Simulator updates     (look here)
describe a change    → Simulator updates     (look here)
npx proto share      → send a share link     (see Share your prototype)

Either way, the paradigm stays clean: one prompt surface, one output surface. You never context-switch between design tools.