Changed maxPriorityFee → maxFee for polygon gas station parsing

[Jon-edge]

CHANGELOG

Does this branch warrant an entry to the CHANGELOG?

• Yes
• No

Dependencies

none

Description

Polygon Gas Fee Bug Analysis

Root Cause

In src/ethereum/ethereumSchema.ts, the Polygon gas station response parser was incorrectly using maxPriorityFee instead of maxFee.

EIP-1559 Fee Structure

EIP-1559 transactions have two fee components:

Component	Description	Destination
Base Fee	Set by network based on demand	Burned (destroyed)
Priority Fee (Miner Tip)	Set by user as incentive	Paid to validator

Total Fee = Base Fee + Priority Fee

The Polygon Gas Station API

The Polygon gas station (https://gasstation.polygon.technology/v2) returns:

{
  "safeLow": { "maxPriorityFee": 20, "maxFee": 35 },
  "standard": { "maxPriorityFee": 25, "maxFee": 40 },
  "fast": { "maxPriorityFee": 30, "maxFee": 50 }
}

• maxPriorityFee = just the tip portion (~20 Gwei)
• maxFee = total fee needed (baseFee + tip, ~35 Gwei)

The Bug

// BEFORE (incorrect)
case 'polygon': {
  const polygonFees = asPolygonGasStation(raw)
  return {
    safeLow: polygonFees.safeLow.maxPriorityFee,  // ❌ Using tip only
    average: polygonFees.standard.maxPriorityFee,
    fast: polygonFees.fast.maxPriorityFee,
    fastest: polygonFees.fast.maxPriorityFee * 1.25
  }
}

The code used maxPriorityFee (20 Gwei) as if it were the total required fee, when it should have used maxFee (35 Gwei).

Impact

Transactions were underpriced by approximately the base fee amount:

Metric	Value
Network required	~35 Gwei
Transaction used	~29 Gwei
Underpayment	~17%

This caused transactions to:

• Take longer to confirm
• Potentially get stuck during high-demand periods
• Fail to be included in blocks when base fee spiked

Evidence

Transaction 0x79884703a6d10dcdae3e0caf50c4d0e193c52ad9708fb6098de287888272359b:

broadcastTx: edge-rjqa2 -- My Polygon wallet:polygon Ee9uY2IuBpERQGblRAcfYD2gKMWPotg8Xu970MnWSs0=\n09:38:15:418: 2025-12-02T17:38:15.418Z | \n  currencyCode: POL\n  nativeAmount: -1885606931818171000\n  txid: 0x79884703a6d10dcdae3e0caf50c4d0e193c52ad9708fb6098de287888272359b\n  networkFee: 606931818171000\n  parentNetworkFee: \n  deviceDescription: Apple iPhone16,2\n  networkFeeOption: standard\n  requestedCustomFee: {\"gasLimit\":\"\",\"gasPrice\":\"\"}\n  feeRateUsed: {\"gasPrice\":\"28.901515151\",\"minerTip\":\"19.911825379\",\"gasLimit\":\"21000\"}

• Broadcast time: 2025-12-02 09:38:15 PST
• Network gas price: ~34.6 Gwei https://prometheus.edge.app/d/47ec48d0-5253-4640-856c-a698ff0b1844/evm-fees?orgId=1&from=2025-12-02T16:45:31.788Z&to=2025-12-02T19:06:30.530Z&timezone=browser&var-chain=polygon
• Transaction gas price: 28.9 Gwei
• Miner tip used: 19.9 Gwei (matches maxPriorityFee from gas station)

The miner tip value (~20 Gwei) directly correlates with maxPriorityFee, confirming the bug.

The Fix

// AFTER (correct)
case 'polygon': {
  const polygonFees = asPolygonGasStation(raw)
  return {
    safeLow: polygonFees.safeLow.maxFee,  // ✅ Using total fee
    average: polygonFees.standard.maxFee,
    fast: polygonFees.fast.maxFee,
    fastest: polygonFees.fast.maxFee * 1.25
  }
}

Additional Fix: Reduced Fee Update Interval

The default fee polling interval is 10 minutes, which can lead to stale fees during volatile periods. Added feeUpdateFrequencyMs: 60000 to polygonInfo.ts to update fees every 1 minute instead.

Files Changed

• src/ethereum/ethereumSchema.ts: Changed maxPriorityFee → maxFee for polygon gas station parsing
• src/ethereum/info/polygonInfo.ts: Added feeUpdateFrequencyMs: 60000 to reduce fee polling from 10 minutes to 1 minute

---

Note

Switch Polygon gas parsing to maxFee and cut fee polling interval to 1 minute.

• Polygon:
  • Gas station parsing: Use maxFee (not maxPriorityFee) for safeLow/average/fast/fastest in src/ethereum/ethereumSchema.ts.
  • Fee polling: Set feeUpdateFrequencyMs: 60000 in src/ethereum/info/polygonInfo.ts to update fees every minute.
• Docs:
  • Update CHANGELOG.md to reflect the above changes.

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