2026-09-13 — CPMM: the protocol takes a share of the creator fee

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TL;DR for integrators

• Both creator-fee collection instructions changed their account lists. This is breaking. CollectCreatorFee gains creator_fee_share at position 5. CollectCreatorFeePermissionless gains amm_config at 5 and creator_fee_share at 6. Both insertions sit before the vaults, so everything after shifts. Rebuild these transactions; do not patch them.
• creator_fee_share must be passed even when it does not exist. It is declared with a seed constraint but read as an unchecked account, so the address must be the canonical PDA at ["creator_fee_share", creator, amm_config] while the account itself is optional. When it is empty, the program falls back to AmmConfig.creator_fee_share_rate.
• AmmConfig gains creator_fee_share_rate, carved out of the padding. The account is still 236 bytes and every existing config keeps deserializing — but the first u64 of the old padding: [u64; 15] is now a live field. Decoders that model the tail as a 15-element array read the share rate as padding[0].
• PoolState is unchanged. 637 bytes, same offsets, same fields. The protocol’s share is booked into the existing protocol_fees_token_{0,1} counters — there is no new counter and no new collection instruction for it.
• protocol_fees_token* now grows outside of swaps. Any monitor that reconciles protocol accrual against trade volume will see jumps at each creator-fee collection.
• A creator-payout estimator that reads creator_fees_token* now overstates. Multiply by (1 − share_rate / 1_000_000), resolved for that (creator, amm_config) pair.
• Two admin instructions are added: CreateCreatorFeeShare and CloseCreatorFeeShare. One new UpdateAmmConfig param: 8 → creator_fee_share_rate.
• No new error codes. The new paths reuse InvalidOwner (6001), InvalidInput (6003) and MathOverflow (6011). 6000–6015 are unchanged.
• An IDL refresh is required — two new instructions, one new account type, two changed account lists, one new config field.

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How the split works

1. CreatorFeeShare PDA at ["creator_fee_share", creator, amm_config] — when the account exists and is owned by CPMM, its share_rate wins.
2. AmmConfig.creator_fee_share_rate — the fee tier’s default, used otherwise.

// states/creator_fee_share.rs
shared_amount  = floor(creator_fee * share_rate / 1_000_000);
creator_amount = creator_fee - shared_amount;

// states/pool.rs — PoolState::settle_creator_fee
self.protocol_fees_token_i = self.protocol_fees_token_i.checked_add(shared_amount_i)?;
self.creator_fees_token_i  = 0;
// creator_amount_i is returned and transferred out to the creator

• Rounding favours the creator. The share floors, so the dust stays with the creator — the same direction as Fees::protocol_fee and Fees::fund_fee, which also carve a share out of an already-accrued fee. 20% of a 1-unit fee is 0, not 1.
• Value is conserved. creator_amount + shared_amount == creator_fee for every rate and every fee up to u64::MAX.
• share_rate = 0 is exactly the old behaviour. Both the default config value and a missing PDA give the creator the whole fee, so nothing changes for any existing pool until an admin sets a rate.

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Account-list changes

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CreateCreatorFeeShare and CloseCreatorFeeShare

pub struct CreatorFeeShare {
    pub bump: u8,
    pub creator: Pubkey,
    pub amm_config: Pubkey,
    pub share_rate: u64,
    pub padding: [u64; 8],
}
// CreatorFeeShare::LEN == 145

• The pool creator is not a party to either instruction and does not sign. The creator account is unchecked — the PDA can be created for a key that owns no pool yet.
• One account covers a (creator, amm_config) pair, so it governs every pool that creator owns on that fee tier. A creator with pools on two tiers needs two accounts to be covered on both.
• There is no update path. init fails on a second create for the same pair; to change a rate, close and re-create.

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UpdateAmmConfig param 8

Some(8) => update_creator_fee_share_rate(amm_config, value),   // asserts value <= 1_000_000

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Riding along

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What did not change

• PoolState — 637 bytes, same fields, same offsets. The protocol’s share reuses the existing protocol bucket rather than adding counters of its own.
• AmmConfig::LEN — still 236 bytes.
• Swap math, quoting, and the k check. The creator fee is charged exactly as before.
• CollectProtocolFee / CollectFundFee — same accounts, same signers. CollectProtocolFee simply has more to collect.
• Error codes. 6000–6015 unchanged; nothing appended.
• Every other instruction, and the program ID.

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Pages updated

• products/cpmm/fees — new “Protocol share of the creator fee” section covering rate resolution, the split arithmetic, rounding, and the integrator consequences; creator_fee_share_rate added to the rates/units list and the default-parameters table; collection-flow table reworked.
• products/cpmm/instructions — breaking-change warning at the top; full account tables for both creator-fee paths; new CreateCreatorFeeShare and CloseCreatorFeeShare sections; UpdateAmmConfig param 8; CollectExcessLamports ordering note; summary and state-change matrix rows.
• products/cpmm/accounts — new CreatorFeeShare account section; AmmConfig layout and padding-carve warning; PoolState fee-counter notes; account-lifecycle rows.
• products/cpmm/overview — creator-fee callout and the “Predictable fees” bullet.
• products/cpmm/math — a note that the split is deliberately absent from swap math.
• products/cpmm/code-demos — warning that pre-upgrade SDK builders emit the old account lists; accrued-fee snippet annotated.
• reference/program-addresses — new “CPMM creator-fee-share authority” section; creator_fee_share added to the PDA-seed block.
• reference/fee-comparison — creator_fee_share_rate called out as a fourth CPMM rate with a different base.