diff --git a/app/vibenet/demos/account/components/TransactionModal.tsx b/app/vibenet/demos/account/components/TransactionModal.tsx
index 74f5d8a..af45c64 100644
--- a/app/vibenet/demos/account/components/TransactionModal.tsx
+++ b/app/vibenet/demos/account/components/TransactionModal.tsx
@@ -64,6 +64,7 @@ import {
   conciseError,
   EstimateRevertedError,
   TxPendingError,
+  TxRevertedError,
   useAccountEngine,
 } from '../useAccountEngine';
 
@@ -155,7 +156,7 @@ export function TransactionModal({ onClose, preset }: TransactionModalProps) {
   const [estimateBlocked, setEstimateBlocked] = useState<string | null>(null);
   const [payerRetry, setPayerRetry] = useState<PayerRetry | null>(null);
   // Error UI is local to this dialog — nothing leaks onto the page behind it.
-  const [error, setError] = useState('');
+  const [error, setError] = useState<DialogError | null>(null);
   const [txStep, setTxStep] = useState<'build' | 'review' | 'submitted'>(
     preset?.calls ? 'review' : 'build',
   );
@@ -218,13 +219,21 @@ export function TransactionModal({ onClose, preset }: TransactionModalProps) {
     });
   };
 
-  const surfaceSendError = (message: string) => {
-    setError(message);
-    toast.error(message);
+  const surfaceSendError = (message: string, txHash?: Hex) => {
+    setError({ message, txHash });
+    toast.error(txHash ? `${message} (${txHash}).` : message);
   };
 
   const sendError = (err: unknown) => {
-    if (err instanceof EstimateRevertedError) setEstimateBlocked(err.reason);
+    if (err instanceof TxRevertedError) {
+      surfaceSendError('Transaction reverted onchain', err.txHash);
+      return;
+    }
+    if (err instanceof EstimateRevertedError) {
+      setEstimateBlocked(err.reason);
+      surfaceSendError(err.reason);
+      return;
+    }
     const e = err as { message?: string; name?: string };
     surfaceSendError(conciseError(e.message ?? String(err)));
   };
@@ -364,7 +373,7 @@ export function TransactionModal({ onClose, preset }: TransactionModalProps) {
   const confirmSend = async (forceEstimate = false, retry: PayerRetry | null = null) => {
     const mode = retry?.kind === 'usdv' ? 'usdv' : gasMode;
     if (retry?.kind === 'usdv') setGasMode('usdv');
-    setError('');
+    setError(null);
     setEstimateBlocked(null);
     setPayerRetry(null);
     setTxStep('submitted');
@@ -404,7 +413,7 @@ export function TransactionModal({ onClose, preset }: TransactionModalProps) {
 
   const startSend = () => {
     if (!callsValid || !activeSigner) return;
-    setError('');
+    setError(null);
     setResult(null);
     setTxStep('review');
   };
@@ -436,12 +445,15 @@ export function TransactionModal({ onClose, preset }: TransactionModalProps) {
                 size="sm"
                 onClick={() => {
                   setTxStep('review');
-                  setError('');
+                  setError(null);
                   setPayerRetry(null);
                 }}
               >
                 Back
               </Button>
+              {error.txHash ? (
+                <ViewTransactionButton href={`${VIBENET_EXPLORER_PATH}/tx/${error.txHash}`} />
+              ) : null}
               <Button variant="primary" size="sm" onClick={() => confirmSend(Boolean(estimateBlocked), payerRetry)}>
                 {retryLabel}
               </Button>
@@ -461,7 +473,7 @@ export function TransactionModal({ onClose, preset }: TransactionModalProps) {
               size="sm"
               onClick={() => {
                 setTxStep('build');
-                setError('');
+                setError(null);
               }}
               disabled={signing}
             >
@@ -867,7 +879,7 @@ type ReviewBodyProps = {
   gasEstimate: number;
   nonceless: boolean;
   txSigner: WalletSigner | null;
-  error: string;
+  error: DialogError | null;
 };
 
 function ReviewBody({
@@ -943,7 +955,7 @@ function ReviewBody({
         {error ? (
           <div className="flex items-start gap-2 py-1 text-[13px] text-bds-red-60 [line-break:anywhere]">
             <ErrorGlyph />
-            {error}
+            <ErrorCopy error={error} />
           </div>
         ) : (
           <div className="flex flex-wrap items-center justify-between gap-3">
@@ -991,7 +1003,7 @@ function SubmittedBody({
 }: {
   signing: boolean;
   submitStatus: '' | 'submitting' | 'confirming';
-  error: string;
+  error: DialogError | null;
   result: SubmittedResult;
 }) {
   if (signing) {
@@ -1013,8 +1025,11 @@ function SubmittedBody({
     return (
       <div className="flex flex-col items-center gap-3 py-10 text-center">
         <ErrorGlyph size={28} />
-        <Text variant="label.regular" className="text-bds-red-60 [line-break:anywhere]">
-          {error}
+        <Text
+          variant="label.regular"
+          className={cn('max-w-full text-bds-red-60', !error.txHash && '[line-break:anywhere]')}
+        >
+          <ErrorCopy error={error} />
         </Text>
       </div>
     );
@@ -1057,6 +1072,25 @@ function SubmittedBody({
   );
 }
 
+type DialogError = { message: string; txHash?: Hex };
+
+function ErrorCopy({ error }: { error: DialogError }) {
+  if (!error.txHash) return error.message;
+  return (
+    <span className="flex max-w-full flex-col items-center gap-1.5">
+      <span>{error.message}</span>
+      <a
+        href={`${VIBENET_EXPLORER_PATH}/tx/${error.txHash}`}
+        target="_blank"
+        rel="noreferrer"
+        className="max-w-full overflow-x-auto font-mono text-[13px] whitespace-nowrap text-base-blue hover:underline"
+      >
+        {error.txHash}
+      </a>
+    </span>
+  );
+}
+
 function ErrorGlyph({ size = 16 }: { size?: number }) {
   return (
     <svg width={size} height={size} viewBox="0 0 40 40" fill="none" className="mt-px shrink-0 text-bds-red-60" aria-hidden="true">
diff --git a/app/vibenet/demos/account/library/revertReason.test.ts b/app/vibenet/demos/account/library/revertReason.test.ts
new file mode 100644
index 0000000..9ddf673
--- /dev/null
+++ b/app/vibenet/demos/account/library/revertReason.test.ts
@@ -0,0 +1,100 @@
+import { encodeErrorResult } from 'viem';
+import { describe, expect, it } from 'vitest';
+
+import { revertReason } from './revertReason';
+
+const abi = [
+  { type: 'error', name: 'Error', inputs: [{ name: 'message', type: 'string' }] },
+  {
+    type: 'error',
+    name: 'ERC20InsufficientBalance',
+    inputs: [
+      { name: 'sender', type: 'address' },
+      { name: 'balance', type: 'uint256' },
+      { name: 'needed', type: 'uint256' },
+    ],
+  },
+  {
+    type: 'error',
+    name: 'ERC20InsufficientAllowance',
+    inputs: [
+      { name: 'spender', type: 'address' },
+      { name: 'allowance', type: 'uint256' },
+      { name: 'needed', type: 'uint256' },
+    ],
+  },
+] as const;
+
+const balanceData = encodeErrorResult({
+  abi,
+  errorName: 'Error',
+  args: ['ERC20: transfer amount exceeds balance'],
+});
+const customBalance = encodeErrorResult({
+  abi,
+  errorName: 'ERC20InsufficientBalance',
+  args: ['0x0000000000000000000000000000000000000001', 10n, 50n],
+});
+const customAllowance = encodeErrorResult({
+  abi,
+  errorName: 'ERC20InsufficientAllowance',
+  args: ['0x0000000000000000000000000000000000000001', 0n, 1n],
+});
+
+describe('revertReason', () => {
+  it('reads an ERC-20 balance revert out of the node message viem hides', () => {
+    const err = {
+      shortMessage: 'RPC Request failed.',
+      details: 'execution reverted: ERC20: transfer amount exceeds balance',
+      message: 'RPC Request failed.\n\nDetails: execution reverted: ERC20: transfer amount exceeds balance\nVersion: viem@2.0.0',
+    };
+    expect(revertReason(err)).toBe('Not enough ERC-20 balance for this transfer.');
+  });
+
+  it('decodes Error(string) revert data when the node message has no reason', () => {
+    const err = {
+      shortMessage: 'RPC Request failed.',
+      details: 'execution reverted',
+      data: balanceData,
+      cause: { code: 3, message: 'execution reverted', data: balanceData },
+    };
+    expect(revertReason(err)).toBe('Not enough ERC-20 balance for this transfer.');
+  });
+
+  it('decodes the ERC-20 custom balance and allowance errors', () => {
+    expect(revertReason({ shortMessage: 'RPC Request failed.', details: 'execution reverted', data: customBalance })).toBe(
+      'Not enough ERC-20 balance for this transfer.',
+    );
+    expect(revertReason({ shortMessage: 'RPC Request failed.', data: customAllowance })).toBe(
+      'Not enough ERC-20 allowance for this transfer.',
+    );
+  });
+
+  it('keeps an unrecognized revert string', () => {
+    expect(revertReason({ details: 'execution reverted: USDV: transfers are paused' })).toBe(
+      'This transaction would revert: USDV: transfers are paused.',
+    );
+  });
+
+  it('names an ETH balance failure', () => {
+    expect(revertReason({ details: 'insufficient funds for gas * price + value' })).toBe(
+      'Not enough ETH to cover this transaction.',
+    );
+  });
+
+  it('reads the vibenet USDV revert, whose reason is the string "balance"', () => {
+    const err = {
+      shortMessage: 'RPC Request failed.',
+      details: 'execution reverted: balance',
+      data: '0x08c379a00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000762616c616e636500000000000000000000000000000000000000000000000000',
+      cause: { code: 3, message: 'execution reverted: balance' },
+    };
+    expect(revertReason(err)).toBe('Not enough ERC-20 balance for this transfer.');
+  });
+
+  it('falls back when the only text is the RPC wrapper', () => {
+    expect(revertReason({ shortMessage: 'RPC Request failed.', message: 'RPC Request failed.' })).toBe(
+      'This transaction would revert.',
+    );
+  });
+});
diff --git a/app/vibenet/demos/account/library/revertReason.ts b/app/vibenet/demos/account/library/revertReason.ts
new file mode 100644
index 0000000..7e2d24c
--- /dev/null
+++ b/app/vibenet/demos/account/library/revertReason.ts
@@ -0,0 +1,141 @@
+// Turn a viem/RPC gas-estimate failure into the reason a person can act on.
+// `eth_estimateGas` throws viem's `RpcRequestError`, whose short message is
+// always "RPC Request failed." The node's revert string and revert data sit
+// on `details` / `data` (and on `cause`).
+
+import { decodeAbiParameters, type Hex } from '@aa';
+
+const ERROR_STRING = '0x08c379a0';
+const INSUFFICIENT_BALANCE = '0xe450d38c';
+const INSUFFICIENT_ALLOWANCE = '0xfb8f41b2';
+
+const BOILERPLATE =
+  /^(rpc request failed\.?|http request failed\.?|missing or invalid parameters\.?|an unknown rpc error occurred\.?|an unknown error occurred\.?|execution reverted(?: for an unknown reason)?\.?|the request took too long to respond\.?)$/i;
+
+const FALLBACK = 'This transaction would revert.';
+
+type ErrLike = {
+  shortMessage?: unknown;
+  details?: unknown;
+  message?: unknown;
+  data?: unknown;
+  cause?: unknown;
+};
+
+/** User-facing explanation of a reverting gas estimate. */
+export function revertReason(err: unknown): string {
+  const decoded = decodeRevertData(collectRevertData(err));
+  if (decoded) return decoded;
+  for (const text of collectTexts(err)) {
+    const human = humanizeRevert(text);
+    if (human !== FALLBACK) return human;
+  }
+  return FALLBACK;
+}
+
+function humanizeRevert(raw: string): string {
+  const text = raw
+    .replace(/^execution reverted:?\s*/i, '')
+    .replace(/:\s*0x[0-9a-fA-F]+$/, '')
+    .trim()
+    .replace(/\.$/, '');
+  if (!text || BOILERPLATE.test(text) || /^0x[0-9a-fA-F]+$/.test(text)) return FALLBACK;
+  // Vibenet's USDV token reverts with the bare string "balance". Other ERC-20s
+  // use the longer OpenZeppelin phrases or the custom error.
+  if (
+    /^(erc-?20:\s*)?balance$|transfer amount exceeds balance|insufficient balance|erc20insufficientbalance/i.test(
+      text,
+    )
+  ) {
+    return 'Not enough ERC-20 balance for this transfer.';
+  }
+  if (/insufficient allowance|transfer amount exceeds allowance|erc20insufficientallowance/i.test(text)) {
+    return 'Not enough ERC-20 allowance for this transfer.';
+  }
+  if (/insufficient funds/i.test(text)) {
+    return 'Not enough ETH to cover this transaction.';
+  }
+  return `This transaction would revert: ${text}.`;
+}
+
+function decodeRevertData(blobs: Hex[]): string | null {
+  for (const data of blobs) {
+    const selector = data.slice(0, 10).toLowerCase();
+    const payload = `0x${data.slice(10)}` as Hex;
+    try {
+      if (selector === ERROR_STRING) {
+        const [message] = decodeAbiParameters([{ type: 'string' }], payload);
+        if (typeof message === 'string' && message.trim()) return humanizeRevert(message);
+      } else if (selector === INSUFFICIENT_BALANCE) {
+        decodeAbiParameters([{ type: 'address' }, { type: 'uint256' }, { type: 'uint256' }], payload);
+        return 'Not enough ERC-20 balance for this transfer.';
+      } else if (selector === INSUFFICIENT_ALLOWANCE) {
+        decodeAbiParameters([{ type: 'address' }, { type: 'uint256' }, { type: 'uint256' }], payload);
+        return 'Not enough ERC-20 allowance for this transfer.';
+      }
+    } catch {
+      /* This blob is not that error. Try the next one. */
+    }
+  }
+  return null;
+}
+
+function collectRevertData(err: unknown): Hex[] {
+  const found: Hex[] = [];
+  walk(err, (node) => {
+    pushHex(found, node.data);
+    if (node.data && typeof node.data === 'object' && node.data !== null && 'data' in node.data) {
+      pushHex(found, (node.data as { data?: unknown }).data);
+    }
+    // Some nodes append the revert blob to the message instead of `data`.
+    // Ignore other hex in the dump (calldata, addresses) so it can't be
+    // mistaken for the revert.
+    for (const value of [node.details, node.message]) pushHex(found, revertHex(value));
+  });
+  return found;
+}
+
+function collectTexts(err: unknown): string[] {
+  const found: string[] = [];
+  walk(err, (node) => {
+    for (const value of [node.details, node.message, node.shortMessage]) {
+      const text = cleanText(value);
+      if (text && !found.includes(text)) found.push(text);
+    }
+  });
+  return found;
+}
+
+function cleanText(value: unknown): string | null {
+  if (typeof value !== 'string') return null;
+  const detail = value.match(/Details:\s*([\s\S]*?)(?:\n\s*Version:|\s*Version:\s|$)/);
+  const text = (detail?.[1] ?? value.split('\n').map((line) => line.trim()).find(Boolean) ?? '').trim();
+  if (!text || BOILERPLATE.test(text)) return null;
+  return text;
+}
+
+function pushHex(found: Hex[], value: unknown) {
+  if (typeof value !== 'string' || !/^0x[0-9a-fA-F]{8,}$/.test(value)) return;
+  if ((value.length - 2) % 2 !== 0) return;
+  const hex = value as Hex;
+  if (!found.includes(hex)) found.push(hex);
+}
+
+function revertHex(value: unknown): string | null {
+  if (typeof value !== 'string') return null;
+  return value.match(/execution reverted:?\s*(0x[0-9a-fA-F]{8,})/i)?.[1] ?? null;
+}
+
+function walk(err: unknown, visit: (node: ErrLike) => void) {
+  const seen = new Set<unknown>();
+  const queue = [err];
+  while (queue.length > 0) {
+    const node = queue.shift();
+    if (!node || typeof node !== 'object' || seen.has(node)) continue;
+    seen.add(node);
+    const record = node as ErrLike;
+    visit(record);
+    if (record.cause && typeof record.cause === 'object') queue.push(record.cause);
+    if (record.data && typeof record.data === 'object') queue.push(record.data);
+  }
+}
diff --git a/app/vibenet/demos/account/useAccountEngine.tsx b/app/vibenet/demos/account/useAccountEngine.tsx
index 1ec041b..8bf64fb 100644
--- a/app/vibenet/demos/account/useAccountEngine.tsx
+++ b/app/vibenet/demos/account/useAccountEngine.tsx
@@ -61,6 +61,7 @@ import { buildPhases, type CallRow, newCallRow, safeGasLimit, valueBearingCallCo
 import type { StoredAccount } from './library/model';
 import { requiredTokenAmount } from './library/payer';
 import { type AaReceiptLike, aaReceiptSucceeded } from './library/receipt';
+import { revertReason } from './library/revertReason';
 import { type Balances, KIND_LABEL, type Persisted, type WalletSigner } from './shared';
 import { useAccounts } from './useAccounts';
 
@@ -70,31 +71,6 @@ const fundAccount = (address: Address) =>
     vibenetApi.faucet.dripUsdv({ address }),
   ]);
 
-/** Best-effort human reason from a viem/RPC error (unwraps the "Missing or invalid
- *  parameters" boilerplate to the underlying details). */
-function estimateFailureReason(err: unknown): string {
-  const e = err as {
-    shortMessage?: string;
-    details?: string;
-    message?: string;
-    cause?: { shortMessage?: string; message?: string };
-  };
-  if (e && typeof e === 'object') {
-    const short = e.shortMessage?.trim();
-    const generic = short && /^Missing or invalid parameters/i.test(short);
-    return (
-      (generic ? e.details : short) ??
-      e.details ??
-      short ??
-      e.cause?.shortMessage ??
-      e.cause?.message ??
-      e.message ??
-      String(err)
-    );
-  }
-  return String(err);
-}
-
 /** Collapse a giant viem error dump to its `Details:` line (or first line) for display. */
 export function conciseError(message: string): string {
   const detail = message.match(/Details:\s*([\s\S]*?)(?:\s*Version:\s|$)/);
@@ -138,6 +114,17 @@ export class TxPendingError extends Error {
   readonly txHash: Hex;
   constructor(hash: Hex) {
     super(`Transaction is pending — not yet included (${hash}).`);
+    this.name = 'TxPendingError';
+    this.txHash = hash;
+  }
+}
+
+/** Thrown when a broadcast transaction was included and then reverted. */
+export class TxRevertedError extends Error {
+  readonly txHash: Hex;
+  constructor(hash: Hex) {
+    super(`Transaction reverted onchain (${hash}).`);
+    this.name = 'TxRevertedError';
     this.txHash = hash;
   }
 }
@@ -147,7 +134,8 @@ export class TxPendingError extends Error {
 export class EstimateRevertedError extends Error {
   readonly reason: string;
   constructor(reason: string) {
-    super(`Gas estimate failed — this transaction would revert: ${reason}`);
+    super(reason);
+    this.name = 'EstimateRevertedError';
     this.reason = reason;
   }
 }
@@ -419,7 +407,7 @@ function useAccountEngineCore() {
       receipt = await getTransactionReceipt(client as never, { hash: txHash }).catch(() => null);
     }
     if (!receipt) receipt = { ...pushed, eip8130: parseReceiptFields(pushed) };
-    if (!aaReceiptSucceeded(receipt as AaReceiptLike)) throw new Error(`Transaction reverted onchain (${txHash}).`);
+    if (!aaReceiptSucceeded(receipt as AaReceiptLike)) throw new TxRevertedError(txHash);
     // Chain facts: the inclusion block's Cobalt `timestampMs`, from the head
     // stream when it has the block, else one block read. Timing is decoration,
     // so a failed read is dropped.
@@ -547,7 +535,7 @@ function useAccountEngineCore() {
         // failure and the gas is spent (self-pay) / rejected (payer).
         gasLimit = BigInt(Math.max(Number(floorGas(true)) * 2, 2_000_000));
       } else if (opts.estimateRevert === 'throw') {
-        throw new EstimateRevertedError(estimateFailureReason(err));
+        throw new EstimateRevertedError(revertReason(err));
       } else {
         gasLimit = floorGas(true);
       }