fix minimum rent error and lamports conversion

app/src/components/CreateEscrowForm.tsx

@@ -16,6 +16,7 @@ import {
 } from '@solana/kit'
 import { useKitTransactionSigner, useWallet, useCluster, useSolanaClient } from '@solana/connector/react'
 import { getCreateEscrowInstructionAsync } from '@descro/sdk'
+import { lamportsFromSol } from '@/util/lamports'
 import type { Address } from '@descro/sdk'
 
 function getNextEscrowId(walletAddress: string): bigint {
@@ -66,7 +67,12 @@ export function CreateEscrowForm({ onCreated }: CreateEscrowFormProps) {
       setError('Invalid SOL amount.')
       return
     }
-    const amountLamports = BigInt(Math.round(amountSolNum * 1e9))
+    const amountLamports = lamportsFromSol(amountSolNum)
+    // Vault is a 0-byte PDA funded entirely by the deposit; must be rent-exempt (~890,880 lamports)
+    if (amountLamports < 890_880n) {
+      setError('Amount too small: minimum is ~0.00089 SOL (vault must be rent-exempt).')
+      return
+    }
 
     let resolverAddress: Address | null = null
     if (resolver.trim()) {

app/src/components/EscrowCard.tsx

@@ -4,6 +4,7 @@ import React from 'react'
 import { YStack, XStack, Text } from 'tamagui'
 import { StatusBadge } from './StatusBadge'
 import type { EscrowAccountWithPda } from '@descro/sdk'
+import { lamportsToSolString } from '@/util/lamports'
 function truncAddr(addr: string): string {
   return `${addr.slice(0, 4)}…${addr.slice(-4)}`
 }
@@ -16,7 +17,7 @@ interface EscrowCardProps {
 
 export function EscrowCard({ item, selected, onSelect }: EscrowCardProps) {
   const { pda, account } = item
-  const solAmount = (Number(account.amount.toString()) / 1e9).toFixed(4)
+  const solAmount = lamportsToSolString(account.amount, 4)
 
   return (
     <YStack

app/src/components/EscrowDetail.tsx

@@ -31,6 +31,7 @@ import {
 } from '@descro/sdk'
 import type { EscrowAccountWithPda } from '@descro/sdk'
 import { useEscrowDetail } from '@/hooks/useEscrowDetail'
+import { lamportsToSolString } from '@/util/lamports'
 
 interface EscrowDetailProps {
   item: EscrowAccountWithPda
@@ -50,7 +51,7 @@ export function EscrowDetail({ item, onAction }: EscrowDetailProps) {
   const [error, setError] = useState<string | null>(null)
   const [success, setSuccess] = useState<string | null>(null)
 
-  const solAmount = (Number(escrow.amount) / 1e9).toFixed(4)
+  const solAmount = lamportsToSolString(escrow.amount, 4)
   const isSeller = address != null && address === escrow.seller
   const isBuyer = address != null && address === escrow.buyer
   const resolverAddr = isSome(escrow.disputeResolver) ? escrow.disputeResolver.value : null

app/src/util/lamports.ts

@@ -0,0 +1,20 @@
+import { lamports, type Lamports } from "@solana/kit";
+
+const LAMPORTS_PER_SOL = 1_000_000_000n;
+
+export function lamportsFromSol(sol: number): Lamports {
+  return lamports(BigInt(Math.round(sol * Number(LAMPORTS_PER_SOL))));
+}
+
+export function lamportsToSolString(amount: Lamports, maxDecimals = 2): string {
+  const whole = amount / LAMPORTS_PER_SOL;
+  const fractional = amount % LAMPORTS_PER_SOL;
+
+  if (fractional === 0n) return whole.toString();
+
+  const decimals = fractional.toString().padStart(9, "0").slice(0, maxDecimals);
+
+  if (decimals.replace(/0+$/, "") === "") return whole.toString();
+
+  return `${whole}.${decimals.replace(/0+$/, "")}`;
+}

programs/descro/src/error.rs

@@ -16,4 +16,6 @@ pub enum EscrowError {
     DisputeTimeoutNotReached,
     #[msg("Vault balance is insufficient for the requested escrow amount")]
     InsufficientVaultBalance,
+    #[msg("Amount must be at least rent-exempt minimum for the vault (~890880 lamports)")]
+    AmountBelowRentMinimum,
 }

programs/descro/src/instructions/create_escrow.rs

@@ -1,5 +1,6 @@
 use anchor_lang::prelude::*;
 use crate::state::{EscrowAccount, EscrowState};
+use crate::EscrowError;
 
 #[derive(Accounts)]
 #[instruction(amount: u64, dispute_resolver: Option<Pubkey>, escrow_id: u64)]
@@ -36,6 +37,9 @@ pub fn handler(
     dispute_resolver: Option<Pubkey>,
     escrow_id: u64,
 ) -> Result<()> {
+    let rent_min = Rent::get()?.minimum_balance(0);
+    require!(amount >= rent_min, EscrowError::AmountBelowRentMinimum);
+
     let escrow = &mut ctx.accounts.escrow_account;
     escrow.seller = ctx.accounts.seller.key();
     escrow.buyer = ctx.accounts.buyer.key();