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Revert "Revert "backend/feat: Stripe payout dynamic transfer top-up f… #1326

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58 changes: 45 additions & 13 deletions lib/mobility-core/src/Kernel/External/Payout/Interface.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,39 @@ createPayoutOrder serviceConfig req = case serviceConfig of
JuspayConfig cfg -> Juspay.createPayoutOrder cfg req
StripeConfig cfg -> do
connectedAccountId <- req.mConnectedAccountId & fromMaybeM (InvalidRequest "connectedAccountId required for Stripe payout")
createTransferResp <- Stripe.createTransfer cfg (mkTransferReq connectedAccountId req)

-- Check Fleet VA available balance and compute adjusted transfer amount if needed.
-- If fleetAvail + transferAmount < payoutAmount, top up the transfer to cover the shortfall.
let computeAdjustedTransfer = do
fleetBalance <- Stripe.getBalance cfg (Just connectedAccountId)
let fleetAvail = Stripe.getAvailableForCurrency req.currency fleetBalance
if fleetAvail + req.transferAmount >= req.amount
then pure (req.transferAmount, Nothing)
else do
let topUp = req.amount - fleetAvail - req.transferAmount
adjustedAmt = req.transferAmount + topUp
-- Verify merchant (platform) VA can cover the increased transfer
merchantBalance <- Stripe.getBalance cfg Nothing
let merchantAvail = Stripe.getAvailableForCurrency req.currency merchantBalance
when (merchantAvail < adjustedAmt) $
throwError $
InvalidRequest $
"Merchant platform account has insufficient balance. Available: "
<> show merchantAvail
<> ", Required: "
<> show adjustedAmt
Comment on lines +58 to +64
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@coderabbitai coderabbitai Bot Jun 2, 2026

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⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Don't leak the merchant platform balance in a client-facing error.

InvalidRequest is surfaced to the API caller. Embedding the platform/merchant account's available balance (and exact required amount) in the message discloses internal financial state to whoever triggers the payout. Log the details internally and return a generic message.

🔒 Proposed fix 
-              when (merchantAvail < adjustedAmt) $
-                throwError $
-                  InvalidRequest $
-                    "Merchant platform account has insufficient balance. Available: "
-                      <> show merchantAvail
-                      <> ", Required: "
-                      <> show adjustedAmt
+              when (merchantAvail < adjustedAmt) $ do
+                logError $
+                  "Merchant platform account has insufficient balance. Available: "
+                    <> show merchantAvail
+                    <> ", Required: "
+                    <> show adjustedAmt
+                throwError $
+                  InvalidRequest "Insufficient merchant platform account balance to complete payout."
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/mobility-core/src/Kernel/External/Payout/Interface.hs` around lines 58 -
64, Replace the client-facing error that leaks merchantAvail and adjustedAmt by
logging the exact balances internally and throwing a generic InvalidRequest
message; specifically, in the branch that checks "when (merchantAvail <
adjustedAmt)" record merchantAvail and adjustedAmt to your internal logger at an
appropriate level (e.g., error/debug) and then call "throwError $
InvalidRequest" with a non-sensitive message like "Merchant platform account has
insufficient balance" (omit numeric details).

logInfo $
"Fleet VA balance insufficient (available: "
<> show fleetAvail
<> "). Topping up transfer by "
<> show topUp
<> " -> adjusted transfer: "
<> show adjustedAmt
pure (adjustedAmt, Just topUp)

(adjustedTransferAmount, merchantTopUpAmount) <- computeAdjustedTransfer

createTransferResp <- Stripe.createTransfer cfg (mkTransferReq connectedAccountId adjustedTransferAmount req)
-- In case if external payout api call failed, we still need to store transferId and transferStatus
result <- withTryCatch "createExternalPayout" $ Stripe.createExternalPayout cfg req
createExternalPayoutResp <- case result of
Expand All @@ -60,22 +92,20 @@ createPayoutOrder serviceConfig req = case serviceConfig of
amount = req.amount,
customerId = Just req.customerId
}
pure $ mkCreatePayoutOrderResp createTransferResp createExternalPayoutResp
pure $ mkCreatePayoutOrderResp merchantTopUpAmount createTransferResp createExternalPayoutResp
where
mkTransferReq :: Text -> CreatePayoutOrderReq -> CreateTransferReq
mkTransferReq connectedAccountId CreatePayoutOrderReq {..} = do
let senderAccountId = TransferPlatformAccount
destinationAccount = TransferConnectedAccount connectedAccountId
mkTransferReq :: Text -> HighPrecMoney -> CreatePayoutOrderReq -> CreateTransferReq
mkTransferReq connectedAccountId adjustedTransferAmount CreatePayoutOrderReq {..} =
CreateTransferReq
{ amount = transferAmount,
{ amount = adjustedTransferAmount,
currency,
senderAccountId,
destinationAccount,
senderAccountId = TransferPlatformAccount,
destinationAccount = TransferConnectedAccount connectedAccountId,
description = Just remark
}

mkCreatePayoutOrderResp :: CreateTransferResp -> CreateExternalPayoutResp -> CreatePayoutOrderResp
mkCreatePayoutOrderResp CreateTransferResp {transferId, transferStatus} CreateExternalPayoutResp {..} =
mkCreatePayoutOrderResp :: Maybe HighPrecMoney -> CreateTransferResp -> CreateExternalPayoutResp -> CreatePayoutOrderResp
mkCreatePayoutOrderResp merchantTopUpAmount CreateTransferResp {transferId, transferStatus} CreateExternalPayoutResp {..} =
CreatePayoutOrderResp
{ orderId,
status,
Expand All @@ -92,7 +122,8 @@ createPayoutOrder serviceConfig req = case serviceConfig of
refunds = Nothing,
payments = Nothing,
fulfillments = Nothing,
customerId
customerId,
merchantTopUpAmount
}

payoutOrderStatus ::
Expand Down Expand Up @@ -128,7 +159,8 @@ payoutOrderStatus serviceConfig req = case serviceConfig of
refunds = Nothing,
payments = Nothing,
fulfillments = Nothing,
customerId
customerId,
merchantTopUpAmount = Nothing
}

createTransfer ::
Expand Down
2 changes: 2 additions & 0 deletions lib/mobility-core/src/Kernel/External/Payout/Interface/Juspay.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,7 @@ createPayoutOrder config req = do
transferStatus = Nothing,
transferId = Nothing,
idAssignedByServiceProvider = Nothing,
merchantTopUpAmount = Nothing,
..
}

Expand Down Expand Up @@ -150,6 +151,7 @@ payoutOrderStatus config req = do
transferStatus = Nothing,
transferId = Nothing,
idAssignedByServiceProvider = Nothing,
merchantTopUpAmount = Nothing,
..
}

Expand Down
22 changes: 22 additions & 0 deletions lib/mobility-core/src/Kernel/External/Payout/Interface/Stripe.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@ module Kernel.External.Payout.Interface.Stripe
( createExternalPayout,
externalPayoutOrderStatus,
createTransfer,
getBalance,
getAvailableForCurrency,
payoutStripeServiceEventWebhook,
castPayoutStatus,
unPayoutId,
Expand Down Expand Up @@ -132,6 +134,26 @@ createTransfer config req = do
mkCreateTransferResp :: Stripe.TransferObject -> CreateTransferResp
mkCreateTransferResp Stripe.TransferObject {..} = CreateTransferResp {transferId = id, transferStatus = TRANSFERRED}

getBalance ::
( Metrics.CoreMetrics m,
EncFlow m r,
HasRequestId r,
MonadReader r m
) =>
StripeConfig ->
Maybe Text ->
m Stripe.BalanceResp
getBalance config mbConnectedAccountId = do
apiKey <- decrypt config.apiKey
Stripe.getBalance config.url apiKey mbConnectedAccountId

-- | Extract available balance for a specific currency from a Stripe BalanceResp.
-- Stripe amounts are in smallest currency unit (cents); converts to HighPrecMoney.
getAvailableForCurrency :: Currency -> Stripe.BalanceResp -> HighPrecMoney
getAvailableForCurrency currency Stripe.BalanceResp {available} =
let currencyText = T.toLower $ show currency
in sum [centsToUsd f.amount | f <- available, f.currency == currencyText]
Comment on lines +152 to +155
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@coderabbitai coderabbitai Bot Jun 2, 2026

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⚠️ Potential issue | 🟠 Major | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Inspect the cents/major-unit converters to confirm scale is currency-agnostic.
ast-grep --pattern 'centsToUsd $_ = $$$'
ast-grep --pattern 'eurToCents $_ = $$$'
ast-grep --pattern 'usdToCents $_ = $$$'
rg -nP --type=haskell -C2 '\b(centsToUsd|eurToCents|usdToCents)\b'

Repository: nammayatri/shared-kernel

Length of output: 12663

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Find the Interface.hs referenced by the review comment
fd -e hs -a Interface.hs lib/mobility-core/src | head -n 50

# Search for the specific comparison expression
rg -n --type=haskell "fleetAvail\s*\+\s*req\.transferAmount\s*>?=\s*req\.amount" lib/mobility-core/src || true

# If not found, search for fleetAvail usage near transferAmount/amount
rg -n --type=haskell "fleetAvail" lib/mobility-core/src | head -n 50

Repository: nammayatri/shared-kernel

Length of output: 2691

🏁 Script executed:

#!/bin/bash
set -euo pipefail

FILE="lib/mobility-core/src/Kernel/External/Payout/Interface.hs"

# Show the relevant block around the comparison
nl -ba "$FILE" | sed -n '1,140p'

# Find the request record type that contains transferAmount/amount
rg -n --type=haskell "transferAmount" lib/mobility-core/src/Kernel/External/Payout/Interface.hs
rg -n --type=haskell "data .*Transfer.*|data .*Payout.*|record.*Transfer|req\.transferAmount" lib/mobility-core/src/Kernel/External/Payout/Interface.hs

# Broader search for where req.amount / transferAmount are built for payout
rg -n --type=haskell "transferAmount\s*=\s*" lib/mobility-core/src/Kernel/External/Payout lib/mobility-core/src/Kernel/External -S
rg -n --type=haskell "req\.amount" lib/mobility-core/src/Kernel/External/Payout -S

Repository: nammayatri/shared-kernel

Length of output: 111

🏁 Script executed:

#!/bin/bash
set -euo pipefail

FILE="lib/mobility-core/src/Kernel/External/Payout/Interface.hs"

# Line-numbered view without nl
cat -n "$FILE" | sed -n '1,120p'

# Find request/type definitions and uses
rg -n --type=haskell "transferAmount" "$FILE"
rg -n --type=haskell "req\.amount|req\.transferAmount|amount\s*=|transferAmount\s*=" lib/mobility-core/src/Kernel/External/Payout -S
rg -n --type=haskell "data .*Payout|data .*Transfer|Create.*Payout|Transfer.*Req|Payout.*Req|record .*Payout" lib/mobility-core/src/Kernel/External/Payout -S

Repository: nammayatri/shared-kernel

Length of output: 25372

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Inspect payout request types
rg -n --type=haskell "data CreatePayoutOrderReq" lib/mobility-core/src/Kernel/External/Payout/Interface/Types.hs
cat -n lib/mobility-core/src/Kernel/External/Payout/Interface/Types.hs | sed -n '1,220p'

# Inspect Stripe payout conversion of req.amount/transferAmount to Stripe minor units
cat -n lib/mobility-core/src/Kernel/External/Payout/Interface/Stripe.hs | sed -n '1,220p'

# Find Currency definition and any decimal/minor-unit scaling logic
rg -n --type=haskell "data Currency|newtype Currency|type Currency" lib/mobility-core/src/Kernel | head -n 50
rg -n --type=haskell "Currency" lib/mobility-core/src/Kernel | rg -n "decim|minor|zero|scale|fraction" | head -n 50 || true
rg -n --type=haskell "zero[-_ ]?decimal|minor unit|decimal" lib/mobility-core/src/Kernel | head -n 50 || true

Repository: nammayatri/shared-kernel

Length of output: 19012

🏁 Script executed:

#!/bin/bash
set -euo pipefail
rg -n --type=haskell "HighPrecMoney" lib/mobility-core/src/Kernel/Types/Price.hs lib/mobility-core/src/Kernel | head -n 50
rg -n --type=haskell "newtype HighPrecMoney|type HighPrecMoney" lib/mobility-core/src/Kernel | head -n 50
rg -n --type=haskell "HighPrecMoney.*cents|cents.*HighPrecMoney|minor.*HighPrecMoney" lib/mobility-core/src/Kernel | head -n 50

Repository: nammayatri/shared-kernel

Length of output: 6407

🏁 Script executed:

#!/bin/bash
set -euo pipefail

FILE="lib/mobility-core/src/Kernel/Types/Price.hs"

# show around HighPrecMoney definition
sed -n '1,140p' "$FILE" | cat -n | sed -n '40,110p'
# show rest where cents/minor may be defined
sed -n '140,260p' "$FILE" | cat -n | head -n 160

Repository: nammayatri/shared-kernel

Length of output: 8353

🏁 Script executed:

#!/bin/bash
set -euo pipefail

rg -n --type=haskell "getAvailableForCurrency|centsToUsd|usdToCents|eurToCents" lib/mobility-core/src/Kernel/External/Payout/Interface/Stripe.hs lib/mobility-core/src/Kernel/External/Payout/Interface.hs lib/mobility-core/src/Kernel/External/Payment/Interface/Stripe.hs
rg -n --type=haskell "getAccuracy\s+INR|data Currency\s*=\s*INR\s*\|" lib/mobility-core/src/Kernel/Types/Price.hs

Repository: nammayatri/shared-kernel

Length of output: 4628

Fix currency minor-unit conversion in getAvailableForCurrency (INR is broken by hardcoded /100).

getAvailableForCurrency filters by f.currency == currencyText, but still converts every matching Stripe amount with centsToUsd:

getAvailableForCurrency :: Currency -> Stripe.BalanceResp -> HighPrecMoney
getAvailableForCurrency currency Stripe.BalanceResp {available} =
  let currencyText = T.toLower $ show currency
   in sum [centsToUsd f.amount | f <- available, f.currency == currencyText]

centsToUsd is hardcoded to / 100, and both usdToCents/eurToCents are hardcoded to * 100—so for Currency = INR (0-decimal in getAccuracy INR = 0), fleetAvail (and the top-up logic guarded by fleetAvail + req.transferAmount >= req.amount in Kernel/External/Payout/Interface.hs) will use the wrong scale.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/mobility-core/src/Kernel/External/Payout/Interface/Stripe.hs` around
lines 152 - 155, getAvailableForCurrency is converting Stripe minor-unit amounts
with the hardcoded centsToUsd (/100), which breaks currencies like INR that have
different decimal accuracy; replace the hardcoded conversion by using the
currency's accuracy (e.g. getAccuracy or existing currency-decimal helper) to
compute scale = 10 ^ accuracy and convert each f.amount from minor units to
HighPrecMoney by dividing by that scale (instead of using centsToUsd), keeping
the currency filter on f.currency; update any helper conversions
(usdToCents/eurToCents) or replace them with a generic minorUnit <-> money
converter so fleetAvail and the transferAmount comparison use the correct scale.


payoutStripeServiceEventWebhook ::
( EncFlow m r,
HasRequestId r,
Expand Down
3 changes: 2 additions & 1 deletion lib/mobility-core/src/Kernel/External/Payout/Interface/Types.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,8 @@ data CreatePayoutOrderResp = CreatePayoutOrderResp
refunds :: Maybe [Text],
payments :: Maybe [Text],
fulfillments :: Maybe [Fulfillment],
customerId :: Maybe Text
customerId :: Maybe Text,
merchantTopUpAmount :: Maybe HighPrecMoney -- Stripe specific: extra amount transferred to cover Fleet VA shortfall
}
deriving (Show, Generic)
deriving anyclass (FromJSON, ToJSON, ToSchema)
Expand Down
40 changes: 40 additions & 0 deletions lib/mobility-core/src/Kernel/External/Payout/Stripe/Flow.hs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
{-# LANGUAGE DerivingStrategies #-}

module Kernel.External.Payout.Stripe.Flow where

import qualified EulerHS.Types as Euler
Expand Down Expand Up @@ -139,3 +141,41 @@ createTransfer url apiKey connectedAccountId transferReq = do
let proxy = Proxy @CreateTransferAPI
eulerClient = Euler.client proxy (PaymentFlow.mkBasicAuthData apiKey) connectedAccountId transferReq
PaymentFlow.callStripeAPI url eulerClient "create-transfer" proxy

-- Balance types
data BalanceFund = BalanceFund
{ amount :: Int, -- Stripe amount in smallest currency unit (e.g. cents)
currency :: Text -- lowercase currency code, e.g. "eur"
}
deriving stock (Show, Generic)
deriving anyclass (FromJSON, ToJSON)

data BalanceResp = BalanceResp
{ available :: [BalanceFund],
pending :: [BalanceFund]
}
deriving stock (Show, Generic)
deriving anyclass (FromJSON, ToJSON)

-- GET /v1/balance
type GetBalanceAPI =
"v1"
:> "balance"
:> BasicAuth "secretkey-password" BasicAuthData
:> Header "Stripe-Account" Text -- Nothing = platform account, Just accountId = connected account
:> Get '[JSON] BalanceResp

getBalance ::
( Metrics.CoreMetrics m,
MonadFlow m,
HasRequestId r,
MonadReader r m
) =>
BaseUrl ->
Text ->
Maybe Text ->
m BalanceResp
getBalance url apiKey connectedAccountId = do
let proxy = Proxy @GetBalanceAPI
eulerClient = Euler.client proxy (PaymentFlow.mkBasicAuthData apiKey) connectedAccountId
PaymentFlow.callStripeAPI url eulerClient "get-balance" proxy
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