feat: add redemption with fixed fee #31
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baroooo
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Dec 19, 2025
bowd
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Jan 14, 2026
bowd
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LGTM, the fee as a parameter is the one thing that felt a bit off and “code smell”-ish, but I don’t see a better way to do that now especially given that we don’t know how the economics will play and and we’ll want to tweak these.
nvtaveras
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Jan 17, 2026
bowd
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Jan 19, 2026
### Description This Pr adds rebalancing to the thresholds defined in the fpmm. This meant changing the formulas for the target amounts: PoolPrice larger thresholds: Everything after the arrow can be ignored 😁 <img width="687" height="622" alt="image" src="https://github.com/user-attachments/assets/c2e1051c-d3a4-4fe0-9e28-3f02c44788fd" /> PoolPrice smaller thresholds: <img width="552" height="589" alt="image" src="https://github.com/user-attachments/assets/db41356c-15a8-4363-91ab-e2afc89b3ed5" /> This Pr also integrated the new fixed fee redemption mechanism in the bold repo mento-protocol/bold#31. You need to checkout this branch from the lib/bold folder in order to build the repo until it is merged. There is still some precision loss on the contraction side of the CDPLiquidityStrategy that I wasn't able to fully erase: My current theory is that it is caused by: 1. The incentives being in bps and the redemption fee in 18dec 2. The redemption potentially hitting multiple troves vs the strategy calculating the collReturned in a single calculation 3. Since we deduct the protocol incentive from the amount we want to redeem and apply the redemptionFee on that reduced amount, we need to calculate the redemptionFee such that the redemptionFee matches the incentive in bps we configured: `if (protocolIncentiveBpsContraction > 0 && liquiditySourceIncentiveBpsContraction > 0) { redemptionFee = (protocolIncentiveBpsContraction * BPS_DENOMINATOR * BPS_TO_FEE_SCALER) / (BPS_DENOMINATOR - liquiditySourceIncentiveBpsContraction); }` Currently, this diff is solved by a small wiggle room I added to the _rebalanceCheck(), allowing up to 10 wei diff on the amountIn which is not great. I also added a check for when the redemption returns more collateral than what we expected: In that case, we transfer that access collateral to the protocolFeeRecipient again, not great (These amounts are at max aroun 2000wei range on large rebalances and are most likely also caused by the redemptionFee calculation vs LiquiditySourceIncentiveBps ) What's missing: - slither ### Other changes ### Tested ### Related issues ### Backwards compatibility ### Documentation --------- Co-authored-by: bowd <dumbogdan@gmail.com>
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This Pr adds a redemption function with a fixed redemption fee to better support rebalancing.
Still missing:
Unit tests for this new function in the collateral registry. Logic is mostly a reduced version of the existing redemption function but tests should still be added 😉