proof.md

Phase 1 Proof

One screen is defined once as typed Effect Native data in examples/signup-activity/index.ts, then rendered by both priority hosts:

Web	Mobile

See Proof Screenshot Runbook for the methodology used to produce and update these images. The committed PNGs are actual browser and iOS simulator captures. The older SVG receipts remain in docs/assets/ as a deprecated backup option when live bitmap capture is unavailable.

The shared module owns the state schema, Schema-backed FormSpec, view function, intent definitions, handlers, and scripted proof steps. It imports effect and @effect-native/core only; it has no DOM, React, React Native, or Expo imports. The web and mobile hosts are thin shells around that module.

Run It

From a fresh clone:

pnpm install
pnpm run check

Run the web host:

pnpm run example:web

Then open http://localhost:4173.

Run the mobile host with the standard Expo flow:

cd examples/mobile
pnpm install
pnpm run ios

The mobile shell is intentionally bare. It supplies Expo, React, and React Native as host dependencies, aliases the local workspace packages through Metro, and embeds EffectNativeSurface.

What The Oracle Checks

scripts/proof-oracle.test.ts replays the same interaction sequence against:

• the headless renderer,
• the DOM renderer under Happy DOM,
• the React Native renderer with an in-memory RN host shim.

For each renderer it asserts the same resulting state, the same intent log, and structurally equivalent view snapshots after every step. The sequence first attempts an invalid submit, proving mapped form errors and first-invalid focus, then submits valid data through the same typed form state machine on headless, DOM, and React Native. This is the Phase 1 receipt: behavior and component structure match across web and mobile because both hosts consume the same typed data.