fix: remove settlement fee (#502)

closes #243

Author: hugomrdias

docs/src/content/docs/developer-guides/payments/rails-settlement.mdx

@@ -130,27 +130,6 @@ Settlement is the process of executing the accumulated payments in a rail. Until
 - **Flexibility**: Allows validators to adjust payments if needed
 - **Finality**: Makes funds available for withdrawal
 
-### Settlement Fee
-
-:::warning[FIL Required for Settlement]
-**Every settlement operation requires 0.0013 FIL** in your wallet (separate from USDFC deposits). This fee is burned to the Filecoin network and is **NOT** returned. Ensure you have sufficient FIL balance before attempting settlement operations.
-:::
-
-Settlement operations require a network fee that is burned (permanently removed from circulation), effectively paying the Filecoin network for providing the settlement service:
-
-- **Amount**: 0.0013 FIL (defined as `SETTLEMENT_FEE` constant)
-- **Mechanism**: The fee is burned to Filecoin's burn actor, `f099` (also known as address `0xff00000000000000000000000000000000000063`), reducing FIL supply
-- **Purpose**: This burn mechanism compensates the network for processing and securing payment settlements
-- **Automatic**: The SDK automatically includes this fee when calling settlement methods
-
-```ts twoslash
-import { ethers } from "ethers";
-// ---cut---
-import { SETTLEMENT_FEE } from "@filoz/synapse-sdk";
-console.log(`Settlement fee: ${ethers.formatEther(SETTLEMENT_FEE)} FIL`);
-// This fee is burned to the network, not paid to any party
-```
-
 ### Performing Settlement
 
 #### Automatic Settlement (Recommended)

docs/src/content/docs/guides/rails-settlement.mdx

@@ -118,21 +118,6 @@ Settlement is the process of executing the accumulated payments in a rail. Until
 - **Flexibility**: Allows validators to adjust payments if needed
 - **Finality**: Makes funds available for withdrawal
 
-### Settlement Fee
-
-Settlement operations require a network fee that is burned (permanently removed from circulation), effectively paying the Filecoin network for providing the settlement service:
-
-- **Amount**: 0.0013 FIL (defined as `SETTLEMENT_FEE` constant)
-- **Mechanism**: The fee is burned to Filecoin's burn actor, `f099` (also known as address `0xff00000000000000000000000000000000000063`), reducing FIL supply
-- **Purpose**: This burn mechanism compensates the network for processing and securing payment settlements
-- **Automatic**: The SDK automatically includes this fee when calling settlement methods
-
-```typescript
-import { SETTLEMENT_FEE } from '@filoz/synapse-sdk'
-console.log(`Settlement fee: ${ethers.formatEther(SETTLEMENT_FEE)} FIL`)
-// This fee is burned to the network, not paid to any party
-```
-
 ### Performing Settlement
 
 #### Automatic Settlement (Recommended)
@@ -159,7 +144,6 @@ For more control, you can use the specific settlement methods:
 Settle up to the current epoch:
 
 ```typescript
-// Settle a specific rail (requires settlement fee)
 const tx = await synapse.payments.settle(railId)
 await tx.wait()
 console.log('Rail settled successfully')
@@ -287,9 +271,7 @@ Common settlement errors and solutions:
 try {
   await synapse.payments.settle(railId)
 } catch (error) {
-  if (error.message.includes('InsufficientNativeTokenForBurn')) {
-    console.error('Insufficient FIL for settlement fee (0.0013 FIL required)')
-  } else if (error.message.includes('NoProgressInSettlement')) {
+  if (error.message.includes('NoProgressInSettlement')) {
     console.error('Rail already settled to current epoch')
   } else if (error.message.includes('RailNotActive')) {
     console.error('Rail is not active or already terminated')

packages/synapse-sdk/src/payments/service.ts

@@ -13,7 +13,6 @@ import {
   EIP2612_PERMIT_TYPES,
   getCurrentEpoch,
   getFilecoinNetworkType,
-  SETTLEMENT_FEE,
   TIMING_CONSTANTS,
   TOKENS,
 } from '../utils/index.ts'
@@ -861,7 +860,7 @@ export class PaymentsService {
 
   /**
    * Settle a payment rail up to a specific epoch (sends a transaction)
-   * Note: This method automatically includes the required network fee (FIL) for burning
+   *
    * @param railId - The rail ID to settle
    * @param untilEpoch - The epoch to settle up to (must be <= current epoch; defaults to current).
    *                     Can be used for partial settlements to a past epoch.
@@ -881,9 +880,7 @@ export class PaymentsService {
     const paymentsContract = this._getPaymentsContract()
 
     // Only set explicit nonce if NonceManager is disabled
-    const txOptions: any = {
-      value: SETTLEMENT_FEE, // Include the settlement fee (NETWORK_FEE in contract) as msg.value
-    }
+    const txOptions: any = {}
     if (this._disableNonceManager) {
       const currentNonce = await this._provider.getTransactionCount(signerAddress, 'pending')
       txOptions.nonce = currentNonce
@@ -904,7 +901,7 @@ export class PaymentsService {
 
   /**
    * Get the expected settlement amounts for a rail (read-only simulation)
-   * Note: The actual settlement will require a network fee (FIL) to be sent with the transaction
+   *
    * @param railId - The rail ID to check
    * @param untilEpoch - The epoch to settle up to (must be <= current epoch; defaults to current).
    *                     Can be used to preview partial settlements to a past epoch.
@@ -921,7 +918,6 @@ export class PaymentsService {
 
     try {
       // Use staticCall to simulate the transaction and get the return values
-      // Include the settlement fee (NETWORK_FEE in contract) in the simulation
       const result = await paymentsContract.settleRail.staticCall(railIdBigint, untilEpochBigint)
 
       return {
@@ -1026,7 +1022,7 @@ export class PaymentsService {
    * Automatically settle a rail, detecting whether it's terminated or active
    * This method checks the rail status and calls the appropriate settlement method:
    * - For terminated rails: calls settleTerminatedRail()
-   * - For active rails: calls settle() with optional untilEpoch (requires settlement fee)
+   * - For active rails: calls settle() with optional untilEpoch
    *
    * @param railId - The rail ID to settle
    * @param untilEpoch - The epoch to settle up to (must be <= current epoch for active rails; ignored for terminated rails)

packages/synapse-sdk/src/test/payments.test.ts

@@ -393,18 +393,6 @@ describe('PaymentsService', () => {
       })
     })
 
-    describe('SETTLEMENT_FEE constant', () => {
-      it('should have correct settlement fee value', () => {
-        // Import the constant
-        const { SETTLEMENT_FEE } = require('../utils/constants.ts')
-
-        assert.exists(SETTLEMENT_FEE)
-        assert.typeOf(SETTLEMENT_FEE, 'bigint')
-        // Settlement fee should be 0.0013 FIL (1300000000000000 attoFIL)
-        assert.equal(SETTLEMENT_FEE, 1300000000000000n)
-      })
-    })
-
     describe('settle', () => {
       it('should settle a rail up to current epoch', async () => {
         server.use(JSONRPC(presets.basic))
@@ -417,9 +405,6 @@ describe('PaymentsService', () => {
         assert.exists(tx.from)
         assert.exists(tx.to)
         assert.exists(tx.data)
-        // Check that the transaction includes the network fee as value
-        assert.exists(tx.value)
-        assert.isTrue(tx.value > 0n)
       })
 
       it('should settle a rail up to specific epoch', async () => {
@@ -543,9 +528,6 @@ describe('PaymentsService', () => {
         assert.exists(tx)
         assert.exists(tx.hash)
         assert.typeOf(tx.hash, 'string')
-        // Check that the transaction includes the settlement fee as value
-        assert.exists(tx.value)
-        assert.isTrue(tx.value > 0n)
       })
 
       it('should settle terminated rail using settleTerminatedRail', async () => {
@@ -599,8 +581,6 @@ describe('PaymentsService', () => {
         assert.exists(tx)
         assert.exists(tx.hash)
         assert.typeOf(tx.hash, 'string')
-        assert.exists(tx.value)
-        assert.isTrue(tx.value > 0n)
       })
 
       it('should accept bigint rail ID', async () => {

packages/synapse-sdk/src/utils/constants.ts

@@ -302,16 +302,6 @@ export const TIMING_CONSTANTS = {
   PIECE_ADDITION_POLL_INTERVAL_MS: 1000, // 1 second
 } as const
 
-/**
- * Settlement fee required for rail settlement operations
- * This is the NETWORK_FEE constant in the Payments contract that gets burned to the Filecoin network
- * Value: 0.0013 FIL (1300000000000000 attoFIL)
- *
- * IMPORTANT: This value must be kept in sync with the Payments contract's NETWORK_FEE constant.
- * If the contract is upgraded with a different fee, this constant must be updated accordingly.
- */
-export const SETTLEMENT_FEE = 1300000000000000n // 0.0013 FIL in attoFIL
-
 /**
  * Recommended RPC endpoints for Filecoin networks
  */

utils/settle-dataset-rails.js

@@ -10,7 +10,7 @@
  */
 
 import { ethers } from 'ethers'
-import { SETTLEMENT_FEE, Synapse } from '../packages/synapse-sdk/src/index.ts'
+import { Synapse } from '../packages/synapse-sdk/src/index.ts'
 import { getCurrentEpoch } from '../packages/synapse-sdk/src/utils/index.ts'
 import { WarmStorageService } from '../packages/synapse-sdk/src/warm-storage/index.ts'
 
@@ -147,7 +147,6 @@ async function main() {
     }
 
     console.log(`Checking settlement amounts for ${railsToSettle.length} rail(s)...`)
-    console.log(`${DIM}Settlement fee: ${ethers.formatEther(SETTLEMENT_FEE)} FIL per transaction${RESET}`)
     console.log('')
 
     let totalSettled = 0n
@@ -231,7 +230,6 @@ async function main() {
         // Check if it's the InsufficientNativeTokenForBurn error
         if (error.message.includes('InsufficientNativeTokenForBurn')) {
           console.log(`  ${YELLOW}Insufficient FIL for network fee${RESET}`)
-          console.log(`  Required: ${ethers.formatEther(SETTLEMENT_FEE)} FIL`)
         }
 
         console.log('')