fix(limit-twap): disable confirm when balance is insufficient - #7804

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No actionable comments were generated in the recent review. 🎉

Walkthrough

Adds live balance validation hooks and wires them into the Limit Orders and TWAP confirm modals so confirmation is blocked and relabeled when balances are insufficient.

Changes

Insufficient Balance Validation

Estimated code review effort: 2 (Simple) | ~12 minutes

Suggested labels: Balances

Suggested reviewers: limitofzero, fairlighteth, elena-zh

Sequence Diagram(s)

sequenceDiagram
  participant User
  participant ConfirmModal
  participant useHasEnoughBalanceForAmount
  participant useIsZeroBalance
  participant useTokensBalancesCombined

  User->>ConfirmModal: Open confirm modal
  ConfirmModal->>useHasEnoughBalanceForAmount: check frozen sell amount
  ConfirmModal->>useIsZeroBalance: check current token balance
  useHasEnoughBalanceForAmount->>useTokensBalancesCombined: read combined balances
  useIsZeroBalance->>useTokensBalancesCombined: read combined balances
  useTokensBalancesCombined-->>useHasEnoughBalanceForAmount: balances
  useTokensBalancesCombined-->>useIsZeroBalance: balances
  useHasEnoughBalanceForAmount-->>ConfirmModal: insufficient? boolean
  useIsZeroBalance-->>ConfirmModal: zero balance? boolean
  alt insufficient balance
    ConfirmModal-->>User: disable confirm, show insufficient balance text
  else sufficient balance
    ConfirmModal-->>User: keep confirm enabled
  end

Poem

A rabbit checked the balances twice,
for TWAP and limits, swift and precise. 🐇
When tokens ran low, the button knew,
and showed a message straight and true.
Hop safe, hop sound, and count each slice!

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Project	Deployment	Actions	Updated (UTC)
swap-dev	Ready	Preview	Jul 7, 2026 12:46pm

@elena-zh good catch — fixed in d0276c8.

Per the issue's note, Limit orders can be placed with amount > balance, so the confirm modal now only disables (and shows Insufficient … balance) when the sell token balance is exactly 0, not whenever amount > balance. So a limit order with amount > balance (balance > 0) now proceeds through Confirm as expected.

TWAP is unchanged — still blocks when balance < order amount, as the issue specifies.

Implementation: added a dedicated useIsZeroBalance(currency) hook for the limit path; TWAP keeps useHasEnoughBalanceForAmount. Also added unit tests for both hooks (covers coderabbit's nitpick about missing coverage). Typecheck/lint pass locally.

@coderabbitai good catch — addressed in 16245ea. useIsZeroBalance now gates on hasFirstLoad so it can't return true (and flash 'Insufficient balance') while values is still the empty default. Added a test for the pre-load case.

#!/bin/bash
cd /repo 2>/dev/null || true
git log --all --oneline | grep -i "16245ea1a" || true
git show 16245ea1a --stat 2>/dev/null | head -50
git show 16245ea1a -- apps/cowswap-frontend/src/modules/combinedBalances/hooks/useIsZeroBalance.ts 2>/dev/null

@tenderdeve Confirmed — commit 16245ea correctly gates useIsZeroBalance on hasFirstLoad, so it returns false until balances have loaded at least once, preventing the transient "Insufficient balance" flash. The updated useMemo deps and the added pre-load test case look good. Thanks for the quick fix!

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