[Bug]: Predict: able to proceed with deposit on Polygon when I have no POL

[bschorchit]

Describe the bug

I'm able to continue and deposit with USDC.e on Polygon when I have no POL.

We should be defaulting to another token for payment and showing an error if users don't have enough gas to proceed.

Expected behavior

No response

Screenshots/Recordings

ScreenRecording_11-14-2025.10-58-05_1.MP4

Steps to reproduce

1. Have USDC.e on Polygon
2. Have no POL
3. Deposit to predict with USDC.e

Error messages or log output

Detection stage

During release testing

Version

7.60.0

Build type

None

Device

iphone 11

Operating system

iOS

Additional context

No response

Severity

No response

[dan437]

@cursor Analyze this MetaMask issue and provide:

1. Problem: What's broken (2-3 sentences)
2. Root Cause: 1-2 likely causes based on evidence
3. Target Repo(s): Which repo needs the fix (this repo/core/transaction-controller/other controllers in the core repo)
4. Solutions: 2-3 approaches with pros/cons, recommend the best one
5. Impact: Severity + complexity estimate

If a solution is clear, suggest a code diff that would resolve the issue, but do not open or create a pull request.

[cursor]

Create PR

Based on my analysis of the codebase, here's my comprehensive breakdown of this issue:

1. Problem

Users can proceed with depositing USDC.e on Polygon when they have no POL (native gas token). The confirmation flow allows the transaction to be submitted without validating that the user has sufficient native tokens to pay for gas fees. This leads to a transaction that will inevitably fail on-chain, wasting user time and causing confusion.

2. Root Cause

Primary Issue: In /workspace/app/components/Views/confirmations/hooks/alerts/useInsufficientBalanceAlert.ts (lines 25-29), TransactionType.predictDeposit is explicitly added to the IGNORE_TYPES list:

const IGNORE_TYPES = [
  TransactionType.perpsDeposit,
  TransactionType.predictDeposit,
  TransactionType.predictWithdraw,
];

This means the insufficient balance check is completely bypassed for predict deposits, even when the user has no POL to pay for gas.

Secondary Issue: The useInsufficientPayTokenNativeAlert hook should catch this case when using a pay-with token, but it only validates when there are available pay token quotes. If no alternative payment tokens are available or the pay token system isn't working on Polygon, this validation doesn't block the transaction.

3. Target Repo(s)

This repository (metamask-mobile) - The issue is in the confirmation flow's gas validation logic. No changes needed in core controllers.

4. Solutions

Solution A: Remove Predict Deposits from IGNORE_TYPES (Recommended)

Approach: Remove TransactionType.predictDeposit from the IGNORE_TYPES array but only ignore the gas fee token check, not the native balance check entirely.

Pros:

• Simple fix
• Ensures users always have enough native tokens for gas
• Consistent with other transaction types
• Blocks transactions early before wasting user time

Cons:

• May need to adjust the logic to still allow pay-with tokens to work properly

Implementation:

// In useInsufficientBalanceAlert.ts
const IGNORE_TYPES = [
  TransactionType.perpsDeposit,
  TransactionType.predictWithdraw, // Keep withdraw as it's different
];

// And update the validation logic to handle predictDeposit specially:
const isSponsoredTransaction = isGasFeeSponsored && isGaslessSupported;
const isPredictDeposit = hasTransactionType(transactionMeta, [TransactionType.predictDeposit]);

const showAlert =
  hasInsufficientBalance &&
  (ignoreGasFeeToken || !selectedGasFeeToken) &&
  !hasTransactionType(transactionMeta, IGNORE_TYPES) &&
  !isSponsoredTransaction &&
  !(isPredictDeposit && selectedGasFeeToken); // Allow predict deposits if alternative gas token selected

Solution B: Add Specific Predict Native Token Validation

Approach: Create a new alert hook useInsufficientNativeForPredictAlert that specifically validates native token balance for predict deposits.

Pros:

• Maintains current architecture
• Can provide predict-specific error messaging
• Doesn't affect other transaction flows

Cons:

• More complex - adds another validation layer
• Duplicates validation logic

Solution C: Ensure Pay-With Token Auto-Selection Works

Approach: Fix the useAutomaticGasFeeTokenSelect to ensure it automatically selects an alternative payment token for predict deposits when insufficient POL is detected.

Pros:

• Uses existing pay-with infrastructure
• Provides seamless UX if alternative tokens available

Cons:

• Doesn't solve the problem if no alternative payment tokens are available
• Still needs a blocking alert as fallback

5. Impact

Severity: High - Users can create failing transactions, causing poor UX and loss of confidence

• Affects all Polygon users with USDC.e but no POL
• Transaction will fail on-chain after user confirms
• May confuse users about why their deposit failed

Complexity: Low-Medium

• Solution A: ~20 lines changed, 1-2 hours
• Solution B: ~50 lines new code, 2-3 hours
• Solution C: ~30 lines changed, 2-3 hours + testing

Recommended Code Fix (Solution A)

// File: app/components/Views/confirmations/hooks/alerts/useInsufficientBalanceAlert.ts

const IGNORE_TYPES = [
  TransactionType.perpsDeposit,
  TransactionType.predictWithdraw,
];

// ... in the hook logic:

const isPredictDeposit = hasTransactionType(transactionMeta, [
  TransactionType.predictDeposit,
]);

// Allow predict deposits to proceed if:
// 1. They have a selected gas fee token (pay-with), OR
// 2. They're sponsored, OR  
// 3. They have sufficient native balance
const showAlert =
  hasInsufficientBalance &&
  !hasTransactionType(transactionMeta, IGNORE_TYPES) &&
  !isSponsoredTransaction &&
  !(isPredictDeposit && selectedGasFeeToken) &&
  (ignoreGasFeeToken || !selectedGasFeeToken);

This ensures predict deposits are blocked when users have insufficient POL unless they've selected an alternative gas payment token.

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