Protocol Fees

The protocol implements several fee mechanisms:

1. Channel Creation Fee (default: 0.02 ETH)

   • Paid when creating a new channel
   • Can be adjusted by the protocol owner
   • Can be retrieved by calling getChannelCreationFee()[/protocol-reference/ProtocolFees#getchannelcreationfee--uint96-external] on ChannelManager

2. Comment Creation Fee (default: 0)

   • Can be enabled for spam prevention
   • Set by the protocol owner
   • Can be retrieved by calling getCommentCreationFee()[/protocol-reference/ProtocolFees#getcommentcreationfee--uint96-external] on ChannelManager

3. Hook Transaction Fee (default: 2%)

   • Applied to the total fee passed to hooks
   • Measured in basis points (1 bp = 0.01%)

4. Hook Fee

   • The hook contract may or may not implement a fee mechanism
   • How the fee is taken is entirely up to the hook contract implementation
   • There is currently no standard way to retrieve the hook fee value
   • We are working on an SDK helper function to estimate the required fee based on known hook contracts

Calculating fee required for posting a comment

⚠️ Before you dive into the details, please note that we've implemented helper functions to calculate the total fee required for posting/editing a comment on a channel. Please see the links at the end of this section.

When posting a comment (including replies), the fee consists of the comment creation fee and the total fee passed to the hook.

Total fee required = Comment creation fee + Total fee passed to the hook

The total fee passed to the hook is calculated as follows:

Total fee passed to the hook = fee required by the hook / (1 - Hook transaction fee)

SDK Helper Functions

We’ve added helper functions to simplify fee calculations when posting or editing comments in a channel. Instead of manually gathering all the required details, these helpers handle the logic for you and return the total fee directly.

• estimateChannelPostCommentFee
• estimateChannelEditCommentFee

Example of using the helper functions can be found in the examples

Example: Calculating fee required for posting a comment on the "Takes" channel

Let's use the "Takes" channel used by interface.social as an example. Here are the steps required to calculate the total fee needed to post a comment:

...
// 1. Get the comment creation fee required by the protocol
 
const { fee: commentCreationFee } = await getCommentCreationFee({
  readContract: publicClient.readContract,
});
 
console.log("Comment creation fee:", commentCreationFee);
 
// 2. Get the hook address from the channel
 
const channel = await getChannel({
  channelId,
  readContract: publicClient.readContract,
});
 
console.log("Channel hook address:", channel.hook);
 
// if the channel has no hook, use the comment creation fee as the total fee required
if (!channel.hook) {
  return commentCreationFee;
}
 
// 3. Get the hook transaction fee required by the protocol
 
const { fee: transactionHookFee } = await getHookTransactionFee({
  readContract: publicClient.readContract,
});
 
console.log("Transaction hook fee:", transactionHookFee);
 
// 4. Since we know the hook is a "Takes" channel hook, we know they have a
// commentFee function to retrieve the fee required by the hook
 
const takesChannelHookCommentFeeABI = parseAbi([
  "function commentFee() view returns (uint256)",
]);
 
const hookCommentFee = await publicClient.readContract({
  abi: takesChannelHookCommentFeeABI,
  address: channel.hook ?? never('hook address not found'),
  functionName: "commentFee",
});
 
console.log("Hook comment fee:", hookCommentFee);
 
// 5. Calculate the total fee required
const totalFee = commentCreationFee + (hookCommentFee * 10000n) / BigInt(10000 - transactionHookFee);
 
console.log("Total fee required:", totalFee);
 
return totalFee;

For full examples, please refer to the examples