Skip to content

fix(samples/frontend): floor default quote amount to corridor minimum #605

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
pengying wants to merge 1 commit into
base: 06-18-fix_samples_frontend_scale_default_quote_amount_by_source_currency_decimals
Choose a base branch
from
+27 −3
Open

fix(samples/frontend): floor default quote amount to corridor minimum #605

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
30 changes: 27 additions & 3 deletions samples/frontend/src/steps/CreateQuote.tsx
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
import { useState, useEffect } from 'react'
import JsonEditor from '../components/JsonEditor'
import ResponsePanel from '../components/ResponsePanel'
import { apiPost } from '../lib/api'
import { apiPost, apiGet } from '../lib/api'

interface Props {
customerId: string | null
Expand Down Expand Up @@ -31,9 +31,29 @@ export default function CreateQuote({ customerId, externalAccountId, destCurrenc
const [loading, setLoading] = useState(false)
const [sourceCurrency, setSourceCurrency] = useState<string>(SOURCE_CURRENCIES[0])
const [cryptoNetwork, setCryptoNetwork] = useState<string>(CRYPTO_NETWORKS[0])
const [minSendingAmount, setMinSendingAmount] = useState<number | null>(null)

const isCryptoSource = CRYPTO_SOURCE_CURRENCIES.includes(sourceCurrency)

// Look up the corridor's minimum sending amount so the default clears it.
// Minimums vary widely by corridor (e.g. USD->EUR ~$23 vs USD->MXN ~$1).
useEffect(() => {
let cancelled = false
setMinSendingAmount(null)
const decimals = SOURCE_CURRENCY_DECIMALS[sourceCurrency] ?? 2
const probe = DEFAULT_SEND_UNITS * 10 ** decimals
apiGet<{ data?: Array<{ minSendingAmount?: number }> }>(
`/api/exchange-rates?sourceCurrency=${sourceCurrency}&destinationCurrency=${destCurrency}&sendingAmount=${probe}`
)
.then((res) => {
if (cancelled) return
const mins = (res.data ?? []).map((r) => r.minSendingAmount ?? 0)
setMinSendingAmount(mins.length ? Math.max(...mins) : null)
})
.catch(() => { if (!cancelled) setMinSendingAmount(null) })

@greptile-apps greptile-apps Bot Jun 18, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

P2 Silent min-fetch failure leaves body at the un-floored default

When the exchange-rates request fails (transient network error, API error, non-ok response), the .catch() handler silently resets minSendingAmount to null. The body useEffect then fires with flooredToMin = 0, so lockedCurrencyAmount falls back to defaultAmount — potentially below the corridor minimum. There is no in-UI indication of this, so a developer would only discover the fallback by seeing the AMOUNT_OUT_OF_RANGE error after submitting the quote. Surfacing the error (e.g. via setError) or at least displaying a warning in the form header would make the failure visible before submission.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: samples/frontend/src/steps/CreateQuote.tsx
Line: 53

Comment:
**Silent min-fetch failure leaves body at the un-floored default**

When the exchange-rates request fails (transient network error, API error, non-`ok` response), the `.catch()` handler silently resets `minSendingAmount` to `null`. The body `useEffect` then fires with `flooredToMin = 0`, so `lockedCurrencyAmount` falls back to `defaultAmount` — potentially below the corridor minimum. There is no in-UI indication of this, so a developer would only discover the fallback by seeing the `AMOUNT_OUT_OF_RANGE` error after submitting the quote. Surfacing the error (e.g. via `setError`) or at least displaying a warning in the form header would make the failure visible before submission.

How can I resolve this? If you propose a fix, please make it concise.

return () => { cancelled = true }
}, [sourceCurrency, destCurrency])

useEffect(() => {
const source: Record<string, unknown> = {
sourceType: "REALTIME_FUNDING",
Expand All @@ -45,7 +65,11 @@ export default function CreateQuote({ customerId, externalAccountId, destCurrenc
// Scale the default amount to the source currency's smallest unit so it isn't
// dust for high-decimal currencies (e.g. 1000 is $10.00 USD but only 0.001 USDC).
const decimals = SOURCE_CURRENCY_DECIMALS[sourceCurrency] ?? 2
const lockedCurrencyAmount = DEFAULT_SEND_UNITS * 10 ** decimals
const defaultAmount = DEFAULT_SEND_UNITS * 10 ** decimals
// Floor to the corridor minimum (+5% buffer for FX drift) when it exceeds the
// default. Don't clamp to maxSendingAmount — it is unreliable for some corridors.
const flooredToMin = minSendingAmount ? Math.ceil(minSendingAmount * 1.05) : 0
const lockedCurrencyAmount = Math.max(defaultAmount, flooredToMin)
setBody(JSON.stringify({
source,
destination: {
Expand All @@ -56,7 +80,7 @@ export default function CreateQuote({ customerId, externalAccountId, destCurrenc
lockedCurrencySide: "SENDING",
purposeOfPayment: "GIFT"
}, null, 2))
}, [customerId, externalAccountId, sourceCurrency, destCurrency, isCryptoSource, cryptoNetwork])
}, [customerId, externalAccountId, sourceCurrency, destCurrency, isCryptoSource, cryptoNetwork, minSendingAmount])

const submit = async () => {
setLoading(true)
Expand Down
Loading