feat(react-dapp-v2): auto-connect and wallet fee when opened from a wallet (H2b)

[ignaciosantise]

Part of WCP4-185 (H2b in-wallet flow, parent WCP4-181).

What

When a wallet opens the React App from its Explore section, it injects window.walletConnectHost before the page loads. On that host launch the app:

1. Connects automatically, with no QR or modal. Once startup finishes, the app calls connect() if no session was restored. Universal Provider sends the pairing URI to the wallet (wc_session_offer) instead of emitting display_uri, and the wallet auto-approves it with its wallet_guide_id. A toast says "Connecting to your wallet…" and then "Connected to {wallet}".
2. Shows the wallet's fee. Universal Provider loads the fee config for this wallet and app from the WalletConnect API. The "Opened from your wallet" card shows the Wallet Guide ID, plus the fee for the active chain: bps, recipient and referral code.
3. Applies the fee in the demo transaction. eth_sendTransaction makes its chain active, then asks for the fee. If there is one, it sends 0.001 ETH × feeBps / 10000 to the recipient.

Opened in a normal browser, nothing changes: same modal, same QR, and authentication as before.

Changes

• Versions: every @walletconnect/* package goes from 2.23.10 to 2.25.1-canary-1, in the dependencies and in pnpm.overrides. That's the canary of walletconnect-monorepo#7361 plus WCP4-183, which bring isHostLaunch(), the bridge hand-off, getWalletFee(), wallet_fee_changed and walletFeeApiUrl.
• Fee API URL: NEXT_PUBLIC_WALLET_FEE_API_URL is passed as walletFeeApiUrl. It defaults to production, which doesn't have the endpoint yet; set it to the staging or a local API for testing.
• No AppKit on a host launch: the app only uses AppKit as the QR modal, and it opens itself on startup.
• Auto-connect runs once, on the first load, so a Disconnect doesn't trigger it again.
• No authentication on a host launch: the canary only sends pair() to the wallet, not authenticate() (WCP4-186).
• Chains: with none selected, a host launch requests Ethereum, Optimism and Arbitrum, which both this app and the RN sample wallet support. This app's RPC map has no Base or OP Sepolia.
• Result modal fix:
  • the overlay is fixed to the viewport, so the card is centered on screen on long pages
  • next.config.js enables the styled-components compiler, so class names match between server and client; they didn't, which left the modal card unstyled after hydration

Testing

Local end to end, with:

• the RN sample wallet in the iOS simulator (react-native-examples#611)
• the fee API from walletconnect-apps#551
• a local database seeded with a 50 bps config for the wallet and this app

What we checked:

• Auto-connect: tapping the Explore tile connects with no modal and no approval screen, and the session carries wallet_guide_id.
• The fee:
  • On Ethereum, which has no recipient, the card says "No wallet fee for this chain", and eth_sendTransaction sends 0 ETH.
  • On Optimism, the card shows 0.5% (50 bps), and the wallet's signing screen shows Amount 0.000005 ETH (value: 0x48c27395000) to the configured recipient.
• Disconnect doesn't reconnect by itself; reopening the tile connects again. Going back and forth restores the session and the fee.
• The result modal (e.g. "User rejected") is centered on screen.
• Checks: tsc --noEmit passes.

Known CI failure: the pr_checks lint/prettier job fails on every recent PR. It runs yarn install --immutable in an app with no yarn.lock, and next lint no longer exists in Next.js 16. Not caused by this PR.

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
appkit-react-wagmi-example	Error		Oct 7, 2026 6:38pm UTC
malicious-dapp-verify-simulation	Ready	Preview	Oct 7, 2026 6:38pm UTC
pos-dapp	Ready	Preview	Oct 7, 2026 6:38pm UTC
react-dapp-v2	Ready	Preview	Oct 7, 2026 6:38pm UTC
wdk-wallet-example	Ready	Preview	Oct 7, 2026 6:38pm UTC

5 Skipped Deployments

Project	Deployment	Actions	Updated
appkit-solana	Ignored		Oct 7, 2026 6:38pm UTC
chain-abstraction-demo	Ignored	Preview	Oct 7, 2026 6:38pm UTC
decentralized-relay-wallet	Ignored	Preview	Oct 7, 2026 6:38pm UTC
react-wallet-v2	Ignored	Preview	Oct 7, 2026 6:38pm UTC
smart-sessions-demo	Ignored	Preview	Oct 7, 2026 6:38pm UTC

[linear]

WCP4-185