Faucet: fix no-op UX and RPC compatibility

Fallback to hardhat_setBalance when anvil_setBalance is unavailable, and show explicit funded/already-funded feedback in UI.

Author: snissn

packages/cli/src/index.ts

@@ -673,6 +673,28 @@ function startUiSiteServer(args: {
     return `0x${n.toString(16)}`;
   }
 
+  async function trySetLocalBalance(rpcUrl: string, addr: string, wei: bigint): Promise<{ ok: boolean; method?: string; error?: string }> {
+    const qty = toHexQuantity(wei);
+    const methods = ['anvil_setBalance', 'hardhat_setBalance'];
+
+    for (const method of methods) {
+      try {
+        await rpcRequest(rpcUrl, method, [addr, qty], 2000);
+        return { ok: true, method };
+      } catch (e: any) {
+        const msg = String(e?.message ?? e ?? '');
+        const unsupported =
+          /method not found/i.test(msg) ||
+          /unsupported/i.test(msg) ||
+          /does not exist/i.test(msg) ||
+          /-32601/.test(msg);
+        if (!unsupported) return { ok: false, method, error: msg };
+      }
+    }
+
+    return { ok: false, error: 'No supported local balance RPC method found (anvil_setBalance, hardhat_setBalance).' };
+  }
+
   function readBody(req: nodeHttp.IncomingMessage, maxBytes = 1024 * 1024): Promise<string> {
     return new Promise((resolve, reject) => {
       let raw = '';
@@ -750,9 +772,14 @@ function startUiSiteServer(args: {
           const targetWei = faucet!.targetWei;
 
           let didSet = false;
+          let setMethod: string | null = null;
           if (oldWei < targetWei) {
-            await rpcRequest(faucet!.rpcUrl, 'anvil_setBalance', [addr, toHexQuantity(targetWei)], 2000);
+            const setResult = await trySetLocalBalance(faucet!.rpcUrl, addr, targetWei);
+            if (!setResult.ok) {
+              return sendJson(res, 400, { ok: false, error: setResult.error ?? 'Failed to set balance.' });
+            }
             didSet = true;
+            setMethod = setResult.method ?? null;
           }
 
           const newHex = (await rpcRequest(faucet!.rpcUrl, 'eth_getBalance', [addr, 'latest'], 2000)) as string;
@@ -765,6 +792,7 @@ function startUiSiteServer(args: {
             targetWei: toHexQuantity(targetWei),
             oldBalanceWei: toHexQuantity(oldWei),
             newBalanceWei: toHexQuantity(newWei),
+            method: setMethod,
             didSet
           });
         } catch (e: any) {

packages/templates/next-export-ui/src/components/FaucetButton.tsx

@@ -14,6 +14,19 @@ type FaucetStatus = {
   reason?: string | null;
 };
 
+function formatWeiHexAsEth(weiHex: unknown): string | null {
+  if (typeof weiHex !== 'string' || !weiHex.startsWith('0x')) return null;
+  try {
+    const wei = BigInt(weiHex);
+    const whole = wei / 10n ** 18n;
+    const frac4 = (wei % 10n ** 18n) / 10n ** 14n;
+    if (frac4 === 0n) return `${whole.toString()} ETH`;
+    return `${whole.toString()}.${frac4.toString().padStart(4, '0')} ETH`;
+  } catch {
+    return null;
+  }
+}
+
 async function tryFetchFaucetStatus(): Promise<FaucetStatus | null> {
   try {
     const res = await fetch('/__tokenhost/faucet', { cache: 'no-store' });
@@ -102,8 +115,16 @@ export default function FaucetButton() {
         const msg = String(json?.error ?? `Faucet failed (HTTP ${res.status}).`);
         throw new Error(msg);
       }
-
-      setTimedNote(`Funded to ~${targetEthRef.current} ETH`);
+      const oldEth = formatWeiHexAsEth(json?.oldBalanceWei);
+      const newEth = formatWeiHexAsEth(json?.newBalanceWei);
+      if (json?.didSet) {
+        const detail = oldEth && newEth ? ` (${oldEth} -> ${newEth})` : '';
+        setTimedNote(`Faucet funded${detail}`);
+      } else if (newEth) {
+        setTimedNote(`Already funded (${newEth})`);
+      } else {
+        setTimedNote(`Already funded (~${targetEthRef.current} ETH)`);
+      }
     } catch (e: any) {
       setTimedNote(String(e?.message ?? e));
     } finally {