Minimal wallet (Expo)

What you get

An Expo (React Native, expo-router) app. It creates or imports a 12-word phrase and keeps it in @anywalletkit/secure-storage-react-native through @anywalletkit/keyring. The home screen shows account 0’s addresses and native balances on Ethereum, Base, Solana, TON, Tron and Bitcoin. A send screen quotes the fee, asks for confirmation through the kit’s policies, signs and shows the hash.

Before you start

• Node 22+, and a Mac with Xcode (or an Android SDK / EAS) for the phone build.
• An empty folder. The agent runs create-expo-app itself.
• No keys: the public RPCs in the reference are enough to start. Put your own endpoints in the config file before you ship.

The prompt

Paste it into your agent as is, in the project folder. The raw file is prompts/01-minimal-wallet.md.

Build a minimal self-custodial multichain wallet app with Expo (React Native, TypeScript, expo-router) on Any Wallet Kit, the `@anywalletkit/*` packages.

Before writing code, read the SDK reference for agents: AGENTS.md in github.com/ultratestbro/anywalletkit, then the guides at https://docs.anywallet.tech/llms-small.txt (the API reference is in llms-full.txt). Use only APIs that appear there.

What the app does:
- Onboarding: create a new 12-word recovery phrase (show it once, then ask for 3 of the words back) or import an existing phrase (validate it).
- Keys: `@anywalletkit/keyring` with `@anywalletkit/secure-storage-react-native` as its secret storage (Face ID / Touch ID with passcode fallback); account names and addresses in AsyncStorage. The phrase never leaves secure storage after onboarding.
- Home: account 0's addresses and native balances on Ethereum, Base, Solana, TON, Tron and Bitcoin, with pull to refresh. A failed read shows an error, never 0.
- Send: pick a chain, enter recipient and amount, show the network fee quote, confirm, send, show the transaction hash.
- Install the React Native / Hermes polyfills exactly as the reference says.

Rules: amounts are bigint base units (format for display without Number); all RPC URLs in one config file (public endpoints are fine); never log or store the phrase or keys anywhere else; wrap every write in the kit's policies with a confirm step.

Done when `npx tsc --noEmit` passes and `npx expo export --platform ios` bundles. Then tell me how to run it on a phone (a development or Release build; Expo Go cannot load the secure-storage native module).

What the result looks like

Roughly this. Agents name files differently, and that is fine:

index.js              # imports ./polyfills first, then expo-router/entry
polyfills.js          # getRandomValues, Buffer, TextDecoder, URL, installHermesRuntime()
metro.config.js       # react-native-fast-pbkdf2 → @anywalletkit/runtime-hermes/fast-pbkdf2
src/config.ts         # every RPC URL
src/wallet/           # keyring + secure storage, balances, send, bigint formatting
src/app/onboarding/   # create (show once, confirm 3 words) / import (validate)
src/app/(home)        # addresses + balances, pull to refresh
src/app/send          # chain, recipient, amount → fee → confirm → hash

Check it works

npx tsc --noEmit
npx expo export --platform ios     # bundles for Hermes: catches polyfill and Metro problems without a device
npx expo prebuild --platform ios && npx expo run:ios --device --configuration Release

On the phone: create a wallet, kill the app, reopen it, and Face ID should unlock the same addresses. Then send a tiny amount on a cheap chain.

Common failures

Symptom	Fix
Metro: Unable to resolve module react-native-fast-pbkdf2	Resolve it to @anywalletkit/runtime-hermes/fast-pbkdf2 in metro.config.js and install expo-crypto (Installation)
crypto.getRandomValues must be defined, Buffer is not defined, TextDecoder is not defined	The polyfills are not first: keep them in their own module and import it first from index.js; package.json "main" must point at index.js
Secure storage throws not-available in Expo Go	It is a native module: use a development or Release build
no-passcode	The device has no passcode; the module refuses to store a secret it cannot protect
TON balance needs an unlock	A TON read-only account needs the public key; store it once (see AGENTS.md)
Signing on Base goes to Ethereum	One EVM network per keyring / registration; open a second keyring for Base (Keyring: more than one EVM network)

Security

Never paste a real recovery phrase into an agent chat, a prompt or a test. Use the public test phrase (abandon abandon … about) while building, then small amounts on a phone build. Read the diff the agent wrote around keys and signing: nothing should log, store or send the phrase, and every write should pass through a review step. Block screenshots on the phrase screen.

Eval

Passed on the first run: 13 min, 68 agent turns, $3.63, Claude Code (Opus 5.5) starting from an empty folder. The app typechecked and bundled.

The run found three gaps, now fixed in the SDK and the reference:

• TON on Metro. wallet-ton needs react-native-fast-pbkdf2 on Metro. The agent wrote a throwing stub; runtime-hermes now ships a working drop-in.
• Base on the keyring. Signing on a second EVM network with the keyring needed a pattern; it is now in the Keyring guide and AGENTS.md.
• TON balances. A TON balance needs the account’s public key; that pattern is in AGENTS.md too.