XMR native

shared/xmr-amount.ts

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+/** Exact, browser-safe amounts. No wallet RPC, exchange rate, custody or signing policy. */
+export const XMR_ATOMIC_UNITS = 1_000_000_000_000n;
+// Preserve the existing processor decimal parser's ten-whole-digit encoding bound.
+// This is NOT a supply limit, an exposure approval, or a wallet-RPC uint64 guarantee.
+export const MAX_XMR_AMOUNT = 10_000_000_000n * XMR_ATOMIC_UNITS - 1n;
+export const XMR_RPC_UINT64_MAX = (1n << 64n) - 1n;
+
+export function assertXmrAmount(amount: bigint): void {
+  if (typeof amount !== 'bigint' || amount < 0n || amount > MAX_XMR_AMOUNT) {
+    throw new Error('Invalid bounded atomic XMR amount');
+  }
+}
+
+/** Decimal user/processor input; never coerce, trim, round, or accept floating point. */
+export function parseXmr(value: string): bigint {
+  if (typeof value !== 'string' || value.length > 23 || !/^(0|[1-9]\d{0,9})(\.\d{1,12})?(?![\s\S])/.test(value)) {
+    throw new Error('Invalid bounded XMR decimal');
+  }
+  const [whole, fraction = ''] = value.split('.');
+  return BigInt(whole) * XMR_ATOMIC_UNITS + BigInt(fraction.padEnd(12, '0'));
+}
+
+/** Canonical display/processor decimal: always twelve fractional places. */
+export function formatXmr(amount: bigint): string {
+  assertXmrAmount(amount);
+  return `${amount / XMR_ATOMIC_UNITS}.${(amount % XMR_ATOMIC_UNITS).toString().padStart(12, '0')}`;
+}
+
+/** JSON/signature/storage representation: canonical base-ten integer string, not a JSON number. */
+export function parseAtomicXmr(value: string): bigint {
+  if (typeof value !== 'string' || value.length > 22 || !/^(0|[1-9]\d{0,21})(?![\s\S])/.test(value)) {
+    throw new Error('Invalid canonical atomic XMR string');
+  }
+  const amount = BigInt(value);
+  assertXmrAmount(amount);
+  return amount;
+}
+
+export function atomicXmrString(amount: bigint): string {
+  assertXmrAmount(amount);
+  return amount.toString();
+}
+
+/** RPC amounts need lossless JSON encoding too; Number(amount) is not safe. */
+export function assertXmrRpcAmount(amount: bigint): void {
+  assertXmrAmount(amount);
+  if (amount > XMR_RPC_UINT64_MAX) throw new Error('XMR amount exceeds wallet-RPC uint64');
+}
+
+/** Independently round commissions down; all sub-atomic remainders stay with the seller. */
+export function xmrCommission(gross: bigint, bps: number): bigint {
+  assertXmrAmount(gross);
+  if (!Number.isSafeInteger(bps) || bps < 0 || bps > 10_000) throw new Error('Invalid commission basis points');
+  return gross * BigInt(bps) / 10_000n;
+}

shared/xmr-pricing.ts

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+import { ADDITIONAL_MARKET_FEE } from './market.ts';
+import { assertXmrAmount, xmrCommission } from './xmr-amount.ts';
+
+/** Allocation only, not proof of payment or an instruction to send/retain funds. */
+export function allocateXmrSale(gross: bigint, hostingBps: number) {
+  assertXmrAmount(gross);
+  if (gross === 0n) throw new Error('Sale price must be positive; use a free transfer for gifts');
+  if (!Number.isSafeInteger(hostingBps) || hostingBps < 0 || hostingBps > 5000) {
+    throw new Error('Hosting commission must be between 0 and 5000 basis points');
+  }
+  const hosting = xmrCommission(gross, hostingBps);
+  const author = xmrCommission(gross, ADDITIONAL_MARKET_FEE.bps);
+  return { gross, hosting, author, sellerBeforeNetworkCosts: gross - hosting - author };
+}
+
+/**
+ * Evaluate an explicitly supplied total seller-funded network-cost budget, including
+ * every applicable leg. Does not choose who funds an author leg or approve a quote.
+ * The budget is a maximum, not revenue; actual costs/unused budget need accounting.
+ */
+export function assessXmrSaleBudget(gross: bigint, hostingBps: number, sellerNetworkBudget: bigint) {
+  const allocation = allocateXmrSale(gross, hostingBps);
+  assertXmrAmount(sellerNetworkBudget);
+  const available = allocation.sellerBeforeNetworkCosts;
+  const viable = sellerNetworkBudget < available;
+  return { ...allocation, sellerNetworkBudget, viable,
+    sellerMinimumNet: viable ? available - sellerNetworkBudget : 0n,
+    // Additional gross-independent funding required to retain at least one atomic unit.
+    fundingShortfall: viable ? 0n : sellerNetworkBudget - available + 1n };
+}