diff --git a/frontend/src/app/markets/[marketId]/dispute/page.tsx b/frontend/src/app/markets/[marketId]/dispute/page.tsx
index 9ea6a80a..86ca87e4 100644
--- a/frontend/src/app/markets/[marketId]/dispute/page.tsx
+++ b/frontend/src/app/markets/[marketId]/dispute/page.tsx
@@ -1,6 +1,6 @@
 'use client';
 
-import { useCallback, useEffect, useState } from 'react';
+import { use, useCallback, useEffect, useState } from 'react';
 import { useAsync } from '@/lib/hooks/useAsync';
 import { useTransaction } from '@/lib/hooks/useTransaction';
 import { describeWriteError } from '@/lib/api/contractErrors';
@@ -47,7 +47,7 @@ async function fetchDisputeStatus(
 }
 
 interface DisputePageProps {
-  params: { marketId: string };
+  params: Promise<{ marketId: string }>;
 }
 
 /**
@@ -62,7 +62,7 @@ interface DisputePageProps {
  * to a nonexistent backend route.
  */
 export default function DisputePage({ params }: DisputePageProps) {
-  const { marketId } = params;
+  const { marketId } = use(params);
   const [reason, setReason] = useState('');
   const wallet = useWallet();
   const tx = useTransaction<{ marketId: string }>();
diff --git a/frontend/src/app/markets/create/page.tsx b/frontend/src/app/markets/create/page.tsx
index ce5b8cad..bf6dd68a 100644
--- a/frontend/src/app/markets/create/page.tsx
+++ b/frontend/src/app/markets/create/page.tsx
@@ -2,6 +2,8 @@
 
 import React from 'react';
 import { useRouter } from 'next/navigation';
+import { ApiError } from '@/lib/api/public-client';
+import { describeWriteError } from '@/lib/api/contractErrors';
 import { getEnvConfig } from '@/lib/env';
 import { useWallet } from '@/lib/wallet/WalletProvider';
 import { getSupportedAsset } from '@/lib/assets';
@@ -116,14 +118,24 @@ export default function CreateMarketPage() {
       );
 
       if (!res.ok) {
-        throw new Error(`Failed to create market (${res.status})`);
+        const body = (await res.json().catch(() => ({}))) as {
+          message?: string;
+          code?: string;
+          details?: Record<string, unknown>;
+        };
+        throw new ApiError(
+          body.message ?? `Failed to create market (${res.status})`,
+          res.status,
+          body.code,
+          body.details
+        );
       }
 
       const data: CreateMarketResponse = await res.json();
       setSuccess(true);
       router.push(`/markets/${data.market_id}`);
     } catch (err) {
-      setErrors({ form: err instanceof Error ? err.message : 'Failed to create market.' });
+      setErrors({ form: describeWriteError(err, 'create') });
     } finally {
       setSubmitting(false);
     }
diff --git a/frontend/src/components/markets/PlaceBetForm.tsx b/frontend/src/components/markets/PlaceBetForm.tsx
index feef858b..d9858676 100644
--- a/frontend/src/components/markets/PlaceBetForm.tsx
+++ b/frontend/src/components/markets/PlaceBetForm.tsx
@@ -3,6 +3,7 @@
 import React from 'react';
 import { api, ApiError } from '../../lib/api/public-client';
 import { useWallet, WALLET_NOT_INSTALLED } from '../../lib/wallet/WalletProvider';
+import { parseBetAmount } from '../../lib/wallet/amount';
 import { placeBetOnChain } from '../../lib/wallet/soroban';
 import { fetchAssetBalance, fetchNativeBalance } from '../../lib/wallet/balance';
 import { SUPPORTED_ASSETS, getSupportedAsset } from '../../lib/assets';
@@ -85,8 +86,7 @@ export const PlaceBetForm: React.FC<PlaceBetFormProps> = ({ market, onSubmitted
 
   const validate = (): string | null => {
     if (selectedOutcome === null) return t('placeBetForm.validationOutcome');
-    const parsed = Number(amount);
-    if (!amount || Number.isNaN(parsed) || parsed <= 0) {
+    if (parseBetAmount(amount) === null) {
       return t('placeBetForm.validationAmount');
     }
     return null;
diff --git a/frontend/src/components/markets/__tests__/PlaceBetForm.test.tsx b/frontend/src/components/markets/__tests__/PlaceBetForm.test.tsx
index e19d1962..e40dd038 100644
--- a/frontend/src/components/markets/__tests__/PlaceBetForm.test.tsx
+++ b/frontend/src/components/markets/__tests__/PlaceBetForm.test.tsx
@@ -342,7 +342,7 @@ describe('PlaceBetForm', () => {
     });
 
     it("shows the market's settlement asset code, not XLM", async () => {
-      const usdc = 'GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN';
+      const usdc = 'GBBD47IF6LWK7P7MDEVSCWR7DPUWV3NY3DTQEVFL4NAT4AQH3ZLLFLA5';
       mockPlaceBet.mockRejectedValue(
         new ApiError('Insufficient balance.', 400, 'CONTRACT_ERROR', { contract_code: 107 })
       );
diff --git a/frontend/src/lib/__tests__/amountAndAssets.test.ts b/frontend/src/lib/__tests__/amountAndAssets.test.ts
new file mode 100644
index 00000000..f15e76ac
--- /dev/null
+++ b/frontend/src/lib/__tests__/amountAndAssets.test.ts
@@ -0,0 +1,28 @@
+import { parseBetAmount } from '../wallet/amount';
+import { getSupportedAssets } from '../assets';
+
+describe('parseBetAmount', () => {
+  it.each(['1e-9', '0x10', '1.123456789', '', '0', '0.0000000', '-1', '.5', '1.'])(
+    'rejects %p',
+    (v) => expect(parseBetAmount(v)).toBeNull()
+  );
+  it('converts exactly to stroops without float rounding', () => {
+    expect(parseBetAmount('1.1234567')).toBe(11234567n);
+    expect(parseBetAmount('9007199254740993')).toBe(90071992547409930000000n);
+    expect(parseBetAmount('0.0000001')).toBe(1n);
+  });
+});
+
+describe('getSupportedAssets', () => {
+  it('keys issuers by network and validates addresses', () => {
+    const usdc = (n: 'PUBLIC' | 'TESTNET') =>
+      getSupportedAssets(n).find((a) => a.code === 'USDC')?.address;
+    expect(usdc('PUBLIC')).not.toBe(usdc('TESTNET'));
+    expect(getSupportedAssets('FUTURENET').some((a) => a.code === 'USDC')).toBe(false);
+  });
+  it('throws on an invalid PIQ address', () => {
+    process.env.NEXT_PUBLIC_PIQ_TOKEN_ADDRESS = 'nope';
+    expect(() => getSupportedAssets('TESTNET')).toThrow(/Invalid address/);
+    delete process.env.NEXT_PUBLIC_PIQ_TOKEN_ADDRESS;
+  });
+});
diff --git a/frontend/src/lib/assets.ts b/frontend/src/lib/assets.ts
index 9ef27449..15cf592f 100644
--- a/frontend/src/lib/assets.ts
+++ b/frontend/src/lib/assets.ts
@@ -10,6 +10,8 @@
  * rejected client-side rather than left for the contract call to fail.
  */
 
+import { StrKey } from '@stellar/stellar-sdk';
+
 export type AssetKind = 'soroban_token' | 'classic_asset';
 
 export interface SupportedAsset {
@@ -23,29 +25,73 @@ export interface SupportedAsset {
   label: string;
 }
 
-export const SUPPORTED_ASSETS: SupportedAsset[] = [
-  {
-    id: 'native:XLM',
-    kind: 'classic_asset',
-    code: 'XLM',
-    address: 'native',
-    label: 'XLM (Stellar Lumens)',
-  },
-  {
-    id: 'classic:USDC:GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN',
-    kind: 'classic_asset',
-    code: 'USDC',
-    address: 'GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN',
-    label: 'USDC (Circle, classic asset)',
-  },
-  {
-    id: 'soroban:PIQ:CBQHNAXSI55GX2GN6D67GK7BHVPSLJUGZQEU7WJ5LKR5PNUCGLIMAO4K',
-    kind: 'soroban_token',
-    code: 'PIQ',
-    address: 'CBQHNAXSI55GX2GN6D67GK7BHVPSLJUGZQEU7WJ5LKR5PNUCGLIMAO4K',
-    label: 'PIQ (PredictIQ token)',
-  },
-];
+export type StellarNetwork = 'PUBLIC' | 'TESTNET' | 'FUTURENET';
+
+const XLM: SupportedAsset = {
+  id: 'native:XLM',
+  kind: 'classic_asset',
+  code: 'XLM',
+  address: 'native',
+  label: 'XLM (Stellar Lumens)',
+};
+
+function usdc(issuer: string, label: string): SupportedAsset {
+  return { id: `classic:USDC:${issuer}`, kind: 'classic_asset', code: 'USDC', address: issuer, label };
+}
+
+/** Per-network issuer/contract addresses; ids on one network never match another's. */
+const ASSETS_BY_NETWORK: Record<StellarNetwork, SupportedAsset[]> = {
+  PUBLIC: [
+    XLM,
+    usdc('GA5ZSEJYB37JRC5AVCIA5MOP4RHTM335X2KGX3IHOJAPP5RE34K4KZVN', 'USDC (Circle, classic asset)'),
+  ],
+  TESTNET: [
+    XLM,
+    usdc('GBBD47IF6LWK7P7MDEVSCWR7DPUWV3NY3DTQEVFL4NAT4AQH3ZLLFLA5', 'USDC (Circle testnet, classic asset)'),
+  ],
+  FUTURENET: [XLM],
+};
+
+export function getStellarNetwork(): StellarNetwork {
+  const raw = (process.env.NEXT_PUBLIC_STELLAR_NETWORK ?? 'TESTNET').trim().toUpperCase();
+  return raw in ASSETS_BY_NETWORK ? (raw as StellarNetwork) : 'TESTNET';
+}
+
+/** True when `address` is `native`, a valid G... issuer, or a valid C... contract id. */
+export function isValidAssetAddress(address: string): boolean {
+  return (
+    address === 'native' ||
+    StrKey.isValidEd25519PublicKey(address) ||
+    StrKey.isValidContract(address)
+  );
+}
+
+/**
+ * Registry for `network`. The PIQ token contract is deployment-specific, so it
+ * comes from NEXT_PUBLIC_PIQ_TOKEN_ADDRESS. Every address is validated; an
+ * invalid one throws at startup instead of failing later on-chain.
+ */
+export function getSupportedAssets(network: StellarNetwork = getStellarNetwork()): SupportedAsset[] {
+  const assets = [...ASSETS_BY_NETWORK[network]];
+  const piq = process.env.NEXT_PUBLIC_PIQ_TOKEN_ADDRESS?.trim();
+  if (piq) {
+    assets.push({
+      id: `soroban:PIQ:${piq}`,
+      kind: 'soroban_token',
+      code: 'PIQ',
+      address: piq,
+      label: 'PIQ (PredictIQ token)',
+    });
+  }
+  for (const asset of assets) {
+    if (!isValidAssetAddress(asset.address)) {
+      throw new Error(`Invalid address for ${asset.code} on ${network}: ${asset.address}`);
+    }
+  }
+  return assets;
+}
+
+export const SUPPORTED_ASSETS: SupportedAsset[] = getSupportedAssets();
 
 export function isSupportedAsset(id: string): boolean {
   return SUPPORTED_ASSETS.some((asset) => asset.id === id);
diff --git a/frontend/src/lib/wallet/amount.ts b/frontend/src/lib/wallet/amount.ts
new file mode 100644
index 00000000..3beeef4a
--- /dev/null
+++ b/frontend/src/lib/wallet/amount.ts
@@ -0,0 +1,13 @@
+/** Stellar amounts: non-negative decimal, at most 7 fractional digits. */
+const AMOUNT_RE = /^\d+(\.\d{1,7})?$/;
+
+/** Minimum bet in stroops; raise once the contract exposes its minimum. */
+export const MIN_BET_STROOPS = 1n;
+
+/** Parse a user-entered amount to stroops, or null if malformed or below the minimum. */
+export function parseBetAmount(amount: string): bigint | null {
+  if (!AMOUNT_RE.test(amount)) return null;
+  const [whole, frac = ''] = amount.split('.');
+  const stroops = BigInt(whole) * 10_000_000n + BigInt(frac.padEnd(7, '0'));
+  return stroops >= MIN_BET_STROOPS ? stroops : null;
+}