QA

dApp QA — Pre-Ship Audit For Scaffold-ETH 2 Builds

What You Probably Got Wrong

"The app deployed, so we are done." For SE2 builds, shipping includes UX correctness, metadata, RPC reliability, contract verification, and branding cleanup.

"The flow is obvious." If Connect, Network, Approve, and Action are not strictly one-at-a-time with proper pending states, users will make duplicate or failing transactions.

"SE2 defaults are fine in production." Default README/footer/title/favicon and default RPC fallbacks are template scaffolding, not production decisions.

"Pass means no console errors." QA pass/fail here is behavioral and user-facing: real wallet flow, mobile deep-link behavior, readable errors, and trust signals must be validated.

Give this to a fresh agent after the dApp is built. The reviewer should:

1. Read the source code (app/, components/, contracts/)
2. Open the app in a browser and click through every flow
3. Check every item below — report PASS/FAIL, don't fix

Fetch crops/SKILL.md first and include a CROPS Review in the report. Simple apps can get a concise baseline review; apps with funds, approvals, custody, wallet permissions, L2/bridge flows, private user data, identity, stablecoins, admin powers, or hosted RPC/indexer/relayer/paymaster/frontend infrastructure need the full four-pillar review.

🚨 Critical: Wallet Flow — Button Not Text

Open the app with NO wallet connected.

• ❌ FAIL: Text saying "Connect your wallet to play" / "Please connect to continue" / any paragraph telling the user to connect
• ✅ PASS: A big, obvious Connect Wallet button is the primary UI element

This is the most common AI agent mistake. Every stock LLM writes a <p>Please connect your wallet</p> instead of rendering <RainbowKitCustomConnectButton />.

🚨 Critical: Four-State Button Flow

The app must show exactly ONE primary button at a time, progressing through:

1. Not connected  → Connect Wallet button
2. Wrong network  → Switch to [Chain] button
3. Needs approval → Approve button
4. Ready          → Action button (Stake/Deposit/Swap)

Check specifically:

• ❌ FAIL: Approve and Action buttons both visible simultaneously
• ❌ FAIL: No network check — app tries to work on wrong chain and fails silently
• ❌ FAIL: Main onchain CTA renders instead of a "Switch to [Chain]" button when the connected wallet is on the wrong network. SE-2's header WrongNetworkDropdown is not sufficient — the action button itself must become the switch CTA, or the user clicks Sign/Stake/Deposit on the wrong chain and eats a silent wagmi error.
• ❌ FAIL: User can click Approve, sign in wallet, come back, and click Approve again while tx is pending
• ✅ PASS: One button at a time. Approve button shows spinner, stays disabled until block confirms onchain. Then switches to the action button.
• ✅ PASS: Action button's render path branches on useChainId() === targetNetwork.id (or equivalent); mismatch renders a useSwitchChain-driven "Switch to [Chain]" button in the same slot as the primary CTA.

In the code: the button's disabled prop must be tied to isPending from useScaffoldWriteContract. Verify it uses useScaffoldWriteContract (waits for block confirmation), NOT raw wagmi useWriteContract (resolves on wallet signature):

grep -rn "useWriteContract" packages/nextjs/

Any match outside scaffold-eth internals → bug.

Watch out: two gaps, both allow double-approve.

isPending from wagmi drops to false when the wallet returns the tx hash — not when the tx confirms. writeContractAsync is still awaiting confirmation. During that window isPending = false AND approveCooldown = false → button re-enables mid-flight.

Fix requires TWO states:

• approvalSubmitting — set at top of handler, cleared in finally {} (covers click→hash gap)
• approveCooldown — set after await resolves, cleared after 4s + refetch (covers confirm→cache gap)

const [approvalSubmitting, setApprovalSubmitting] = useState(false);
const [approveCooldown, setApproveCooldown] = useState(false);

const handleApprove = async () => {
  if (approvalSubmitting || approveCooldown) return;
  setApprovalSubmitting(true);
  try {
    await approveWrite({ functionName: "approve", args: [spender, amount] });
    setApproveCooldown(true);
    setTimeout(() => { setApproveCooldown(false); refetchAllowance(); }, 4000);
  } catch (e) {
    notifyError("Approval failed");
  } finally {
    setApprovalSubmitting(false); // must be finally — releases on rejection too
  }
};

<button disabled={isPending || approvalSubmitting || approveCooldown}>

• ❌ FAIL: Button disabled only reads isPending or only approveCooldown
• ❌ FAIL: No approvalSubmitting state, or it's not cleared in finally {}
• ✅ PASS: disabled={isPending || approvalSubmitting || approveCooldown} with both states managed correctly

🚨 Critical: SE2 Branding Removal

AI agents treat the scaffold as sacred and leave all default branding in place.

• Footer: Remove BuidlGuidl links, "Built with 🏗️ SE2", "Fork me" link, support links. Replace with project's own repo link or clean it out
• Tab title: Must be the app name, NOT "Scaffold-ETH 2" or "SE-2 App" or "App Name | Scaffold-ETH 2"
• README: Must describe THIS project. Not the SE2 template README. Remove "Built with Scaffold-ETH 2" sections and SE2 doc links
• Favicon: Must not be the SE2 default

Important: CROPS Review for Trust Assumptions

• ❌ FAIL: No CROPS Review block in the QA report.
• ❌ FAIL: The CROPS Review lists generic values but does not name who can block users, what data leaks, who controls funds/upgrades/recovery, and how users exit.
• ❌ FAIL: The app has production-relevant trust assumptions (funds, approvals, custody, wallet permissions, L2/bridge, private data, identity, stablecoins, admin powers, hosted RPC/indexer/relayer/paymaster/frontend) but the CROPS Review is only a short gate and never uses crops/SKILL.md for the deep template.
• ✅ PASS: A concrete CROPS Review block is present, names the chosen default, accepted compromises, and the user's escape path. Depth matches the app's trust assumptions.

Important: Contract Address Display

• ❌ FAIL: The deployed contract address appears nowhere on the page
• ✅ PASS: Contract address displayed using <Address/> component (blockie, ENS, copy, explorer link)

Agents display the connected wallet address but forget to show the contract the user is interacting with.

Important: Address Input — Always <AddressInput/>

EVERY input that accepts an Ethereum address must use <AddressInput/>, not a plain <input type="text">.

• ❌ FAIL: <input type="text" placeholder="0x..." value={addr} => setAddr(e.target.value)} />
• ✅ PASS: <AddressInput value={addr} placeholder="0x... or ENS name" />

<AddressInput/> gives you ENS resolution (type "vitalik.eth" → resolves to address), blockie avatar preview, validation, and paste handling. A raw text input is unacceptable for address collection.

In SE2, it's in @scaffold-ui/components:

import { AddressInput } from "@scaffold-ui/components";
// or
import { AddressInput } from "~~/components/scaffold-eth"; // if re-exported

Quick check:

grep -rn 'type="text"' packages/nextjs/app/ | grep -i "addr\|owner\|recip\|0x"
grep -rn 'placeholder="0x' packages/nextjs/app/

Any match → FAIL. Replace with <AddressInput/>.

The pair: <Address/> for display, <AddressInput/> for input. Always.

Important: USD Values

• ❌ FAIL: Token amounts shown as "1,000 TOKEN" or "0.5 ETH" with no dollar value
• ✅ PASS: "0.5 ETH (~$1,250)" with USD conversion

Agents never add USD values unprompted. Check every place a token or ETH amount is displayed, including inputs.

Important: OG Image Must Be Absolute URL

• ❌ FAIL: images: ["/thumbnail.jpg"] — relative path, breaks unfurling everywhere
• ✅ PASS: images: ["https://yourdomain.com/thumbnail.jpg"] — absolute production URL

Quick check:

grep -n "og:image\|images:" packages/nextjs/app/layout.tsx

Important: RPC & Polling Config

Open packages/nextjs/scaffold.config.ts:

• ❌ FAIL: pollingInterval: 30000 (default — makes the UI feel broken, 30 second update lag)
• ✅ PASS: pollingInterval: 3000
• ❌ FAIL: Using default Alchemy API key that ships with SE2
• ❌ FAIL: Code references process.env.NEXT_PUBLIC_* but the variable isn't actually set in the deployment environment (Vercel/hosting). Falls back to public RPC like mainnet.base.org which is rate-limited
• ✅ PASS: rpcOverrides uses process.env.NEXT_PUBLIC_* variables AND the env var is confirmed set on the hosting platform
• ❌ FAIL: services/web3/wagmiConfig.tsx still includes bare http() fallback transport (silently hits public RPCs in parallel, causing rate limits)
• ✅ PASS: Bare http() fallback removed; only intended configured transports remain

Verify the env var is set, not just referenced. AI agents will change the code to use process.env, see the pattern matches PASS, and move on — without ever setting the actual variable on Vercel/hosting. Check:

vercel env ls | grep RPC

Important: SE2 externalContracts.ts Registration

Scaffold hooks only work with contracts registered in deployedContracts.ts (auto-generated) or externalContracts.ts (manual). If external contracts are not registered, frontend reads/writes silently fail.

• ❌ FAIL: Frontend code references token/protocol contracts that are missing from packages/nextjs/contracts/externalContracts.ts
• ❌ FAIL: deployedContracts.ts manually edited to add external contracts
• ✅ PASS: All external contracts are defined in externalContracts.ts with correct chain, address, and ABI

Example:

export default {
  8453: {
    USDC: {
      address: "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      abi: [...],
    },
  },
} as const;

Never edit deployedContracts.ts directly. It is regenerated on deploy.

Important: Dark Mode — No Hardcoded Dark Backgrounds

AI agents love the aesthetic of a dark UI and will hardcode it directly on the page wrapper:

// ❌ FAIL — hardcoded black background, ignores system preference AND DaisyUI theme
<div className="min-h-screen bg-[#0a0a0a] text-white">

This bypasses the entire DaisyUI theme system. Light-mode users get a black page. The SwitchTheme toggle in the SE2 header stops working. prefers-color-scheme is ignored.

Check for this pattern:

grep -rn 'bg-\[#0\|bg-black\|bg-gray-9\|bg-zinc-9\|bg-neutral-9\|bg-slate-9' packages/nextjs/app/

Any match on a root layout div or page wrapper → FAIL.

• ❌ FAIL: Root page wrapper uses a hardcoded hex color or Tailwind dark bg class (bg-[#0a0a0a], bg-black, bg-zinc-900, etc.)
• ❌ FAIL: SwitchTheme toggle is present in the header but the page ignores data-theme entirely
• ✅ PASS: All backgrounds use DaisyUI semantic variables — bg-base-100, bg-base-200, text-base-content
• ✅ PASS (dark-only exception): Theme is explicitly forced via data-theme="dark" on <html> AND the <SwitchTheme/> component is removed from the header

The fix:

// ✅ CORRECT — responds to light/dark toggle and prefers-color-scheme
<div className="min-h-screen bg-base-200 text-base-content">

Important: Phantom Wallet in RainbowKit

Phantom is NOT in the SE2 default wallet list. A lot of users have Phantom — if it's missing, they can't connect.

• ❌ FAIL: Phantom wallet not in the RainbowKit wallet list
• ✅ PASS: phantomWallet is in wagmiConnectors.tsx

Important: Mobile Deep Linking

RainbowKit v2 / WalletConnect v2 does NOT auto-deep-link to the wallet app. It relies on push notifications instead, which are slow and unreliable. You must implement deep linking yourself.

On mobile, when a user taps a button that needs a signature, it must open their wallet app. Test this: open the app on a phone, connect a wallet via WalletConnect, tap an action button — does the wallet app open with the transaction ready to sign?

• ❌ FAIL: Nothing happens, user has to manually switch to their wallet app
• ❌ FAIL: Deep link fires BEFORE the transaction — user arrives at wallet with nothing to sign
• ❌ FAIL: window.location.href = "rainbow://" called before writeContractAsync() — navigates away and the TX never fires
• ❌ FAIL: It opens the wrong wallet (e.g. opens MetaMask when user connected with Rainbow)
• ❌ FAIL: Deep links inside a wallet's in-app browser (unnecessary — you're already in the wallet)
• ✅ PASS: Every transaction button fires the TX first, then deep links to the correct wallet app after a delay

How to implement it

Pattern: writeAndOpen helper. Fire the write call first (sends the TX request over WalletConnect), then deep link after a delay to switch the user to their wallet:

const writeAndOpen = useCallback(
  <T,>(writeFn: () => Promise<T>): Promise<T> => {
    const promise = writeFn(); // Fire TX — does gas estimation + WC relay
    setTimeout(openWallet, 2000); // Switch to wallet AFTER request is relayed
    return promise;
  },
  [openWallet],
);

// Usage — wraps every write call:
await writeAndOpen(() => gameWrite({ functionName: "click", args: [...] }));

Why 2 seconds? writeContractAsync must estimate gas, encode calldata, and relay the signing request through WalletConnect's servers. 300ms is too fast — the wallet won't have received the request yet.

Detecting the wallet: connector.id from wagmi says "walletConnect", NOT "rainbow" or "metamask". You must check multiple sources:

const openWallet = useCallback(() => {
  if (typeof window === "undefined") return;
  const isMobile = /iPhone|iPad|iPod|Android/i.test(navigator.userAgent);
  if (!isMobile || window.ethereum) return; // Skip if desktop or in-app browser

  // Check connector, wagmi storage, AND WalletConnect session data
  const allIds = [connector?.id, connector?.name,
    localStorage.getItem("wagmi.recentConnectorId")]
    .filter(Boolean).join(" ").toLowerCase();

  let wcWallet = "";
  try {
    const wcKey = Object.keys(localStorage).find(k => k.startsWith("wc@2:client"));
    if (wcKey) wcWallet = (localStorage.getItem(wcKey) || "").toLowerCase();
  } catch {}
  const search = `${allIds} ${wcWallet}`;

  const schemes: [string[], string][] = [
    [["rainbow"], "rainbow://"],
    [["metamask"], "metamask://"],
    [["coinbase", "cbwallet"], "cbwallet://"],
    [["trust"], "trust://"],
    [["phantom"], "phantom://"],
  ];

  for (const [keywords, scheme] of schemes) {
    if (keywords.some(k => search.includes(k))) {
      window.location.href = scheme;
      return;
    }
  }
}, [connector]);

Key rules:

1. Fire TX first, deep link second. Never window.location.href before the write call
2. Skip deep link if window.ethereum exists — means you're already in the wallet's in-app browser
3. Check WalletConnect session data in localStorage — connector.id alone won't tell you which wallet
4. Use simple scheme URLs like rainbow:// — not rainbow://dapp/... which reloads the page
5. Wrap EVERY write call — approve, action, claim, batch — not just the main one

🚨 Critical: Contract Verification on Block Explorer

After deploying, every contract MUST be verified on the block explorer. Unverified contracts are a trust red flag — users can't read the source code, and it looks like you're hiding something.

• ❌ FAIL: Block explorer shows "Contract source code not verified" for any deployed contract
• ✅ PASS: All deployed contracts show verified source code with a green checkmark on the block explorer

How to check: Take each contract address from deployedContracts.ts, open it on the block explorer (Etherscan, Basescan, Arbiscan, etc.), and look for the "Contract" tab with a ✅ checkmark. If it shows bytecode only — not verified.

How to fix (SE2):

yarn verify --network mainnet   # or base, arbitrum, optimism, etc.

How to fix (Foundry):

forge verify-contract <ADDRESS> <CONTRACT> --chain <CHAIN_ID> --etherscan-api-key $ETHERSCAN_API_KEY

AI agents frequently skip verification because yarn deploy succeeds and they move on. Deployment is not done until verification passes.

Important: Button Loading State — DaisyUI loading Class Is Wrong

AI agents almost always implement button loading states incorrectly when using DaisyUI + SE2.

The mistake: Adding loading as a class directly on a btn:

// ❌ FAIL — DaisyUI's `loading` class on a `btn` replaces the entire button content
// with a spinner that fills the full button. No text, misaligned, looks broken.
<button className={`btn btn-primary ${isPending ? "loading" : ""}`}>
  {isPending ? "Approving..." : "Approve"}
</button>

The fix: Remove loading from the button class, add an inline loading-spinner span inside the button alongside the text:

// ✅ PASS — small spinner inside the button, text visible next to it
<button className="btn btn-primary" disabled={isPending}>
  {isPending && <span className="loading loading-spinner loading-sm mr-2" />}
  {isPending ? "Approving..." : "Approve"}
</button>

Check for this in code:

grep -rn '"loading"' packages/nextjs/app/

Any "loading" string in a button's className → FAIL.

• ❌ FAIL: className={... isPending ? "loading" : ""} on a button
• ✅ PASS: <span className="loading loading-spinner loading-sm" /> inside the button

Important: SE2 Pill-Shaped Inputs (--radius-field)

SE2 DaisyUI theme defaults to --radius-field: 9999rem, which creates pill-shaped textareas/selects and often clips content.

• ❌ FAIL: --radius-field: 9999rem remains in packages/nextjs/styles/globals.css
• ✅ PASS: --radius-field is changed to 0.5rem (or similar) in both light and dark theme blocks

Fix in theme (not per component):

/* In BOTH @plugin "daisyui/theme" blocks */
--radius-field: 0.5rem;

Do not patch this by sprinkling rounded-* utility classes per input; fix it once at theme level.

SE2 References

• Docs: https://docs.scaffoldeth.io/
• UI Components: https://ui.scaffoldeth.io/
• SpeedRun Ethereum: https://speedrunethereum.com/

Audit Summary

Report each as PASS or FAIL:

Ship-Blocking

• Wallet connection shows a BUTTON, not text
• Wrong network shows a Switch button in the primary CTA slot (not only in the header dropdown)
• One button at a time (Connect → Network → Approve → Action)
• Approve button locked through full cycle: approvalSubmitting (click→hash), approveCooldown (confirm→cache refresh) — both states required, both on the disabled prop
• Contracts verified on block explorer (Etherscan/Basescan/Arbiscan) — source code readable by anyone
• CROPS Review present in the QA report: names the chosen default, accepted compromises, who can block users, what data leaks, who controls funds/upgrades/recovery, and the user's escape path
• SE2 footer branding removed
• SE2 tab title removed
• SE2 README replaced

Should Fix

• Contract address displayed with <Address/>
• Every address input uses <AddressInput/> — no raw <input type="text"> for addresses
• USD values next to all token/ETH amounts
• OG image is absolute production URL
• pollingInterval is 3000
• RPC overrides set (not default SE2 key) AND env var confirmed set on hosting platform
• Favicon updated from SE2 default
• --radius-field in globals.css changed from 9999rem to 0.5rem (or similar) — no pill-shaped textareas
• Every contract error mapped to a human-readable message — no silent catch blocks, no raw hex selectors
• No hardcoded dark backgrounds — page wrapper uses bg-base-200 text-base-content (or data-theme="dark" forced + <SwitchTheme/> removed)
• Button loaders use inline <span className="loading loading-spinner loading-sm" /> — NOT className="... loading" on the button itself
• Phantom wallet in RainbowKit wallet list
• Mobile: ALL transaction buttons deep link to wallet (fire TX first, then setTimeout(openWallet, 2000))
• Mobile: wallet detection checks WC session data, not just connector.id
• Mobile: no deep link when window.ethereum exists (in-app browser)