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Rehype Doppler Hook

Use this skill for anything involving Doppler’s Rehype hook: configuring fee distributions, decoding swap flows, running invariant suites, or shipping deployments.

When To Activate

• User references “rehype”, Doppler hooks, fee distributions, buybacks, or beneficiary payouts
• Tasks touch src/dopplerHooks/RehypeDopplerHook.sol, IRehypeHook.sol, or related deployments/tests
• Need to explain hook-driven swap behavior, collect fees, or update pool configuration

Prerequisites

• Doppler repo checked out and current (whetstoneresearch/doppler)
• Foundry toolchain installed for forge/cast
• Access to the Airlock + DopplerHookInitializer environment when mutating on-chain state
• Uniswap V4 Pool Manager RPC endpoint for simulations or deployments

Quick Start

1. Identify the pool asset + numeraire by inspecting DopplerHookInitializer.getState(asset).
2. Confirm Rehype is enabled for the pool (ON_INITIALIZATION_FLAG | ON_SWAP_FLAG).
3. Load current fee distribution with RehypeDopplerHook.getFeeDistributionInfo(poolId) to baseline percentages.
4. Move to the relevant workflow below (configuration, fee collection, testing, deployment).

Core Workflows

Configure / Tune Fee Distribution

1. Gather desired percentages (asset buyback, numeraire buyback, beneficiary, LP) that must sum to WAD (1e18).
2. Call setFeeDistribution(poolId, ...) from the buybackDst address (stored in getPoolInfo[poolId].buybackDst).
   • Only the buybackDst can update fee distribution; expect SenderNotAuthorized on mismatch.
3. Record reasoning + math (ideally in governance artifacts) because improper splits can stall swaps.
4. See Configuration for calldata templates and sanity checks.

Note: The previous setFeeDistributionByBeneficiary() function has been removed. Fee distribution updates are now controlled exclusively by buybackDst.

Collect Beneficiary Fees

1. Resolve the target asset (the Doppler token) and call RehypeDopplerHook.collectFees(asset).
2. The hook transfers accumulated beneficiaryFees0/1 to buybackDst and zeroes out the counters.
3. Confirm ERC20 balances + hook storage match expectations before/after collection.
4. Document tx hash for accounting.

Collect Airlock Owner Fees (5% Protocol Fee)

1. The Rehype hook automatically splits 5% of all swap fees to the Airlock owner (stored separately as airlockOwnerFees0/1).
2. The Airlock owner calls RehypeDopplerHook.claimAirlockOwnerFees(asset) to claim accumulated fees.
3. Only the current airlock.owner() can call this function; expect SenderNotAirlockOwner on mismatch.
4. Returns (fees0, fees1) indicating amounts transferred.

Understand Swap Flow / Debugging

1. _onSwap collects swap output fees, executes asset + numeraire buybacks, rebalances, and reinvests LP before crediting beneficiary balances.
2. Use _collectSwapFees math to estimate deductions: fee = outputAmount * customFee / 1e6.
3. Fee Split: 5% of collected fees go to airlockOwnerFees, remaining 95% go to fees0/1 for distribution.
4. Inspect getHookFees(poolId) for:
   • fees0/fees1 (distributable fees for buybacks/LP/beneficiary)
   • beneficiaryFees0/1 (accumulated beneficiary share, claimable via collectFees)
   • airlockOwnerFees0/1 (5% protocol fee, claimable via claimAirlockOwnerFees)
5. Troubleshoot common errors in the table below.

Testing Changes

1. Run targeted unit tests: forge test --match-contract RehypeDopplerHook -vv.
2. Execute invariants from test/invariant/rehype/ using forge test --match-contract RehypeInvariants (ERC20) and RehypeInvariantsETH (native path).
3. For fuzzing issues, consult handler design + risk matrix in Testing.
4. Capture seed(s) that reproduce failures; investigate _rebalanceFees, settlement paths, or _collectSwapFees underflows.

Deploy / Upgrade Hook Instances

1. Edit doppler/script/deployments.config.toml with the target chain parameters (CreateX, initializer, pool manager).
2. Run forge script script/DeployRehypeDopplerHook.s.sol --rpc-url <network> --broadcast --sig "run()".
3. Script enforces Create3 deterministic address parity; expect revert if mismatch.
4. After broadcasting, update doppler/Deployments.md with the new address + commit hash.
5. Details live in Deployment.

Troubleshooting Cheat Sheet

References

• Configuration playbooks
• Testing + invariants guide
• Deployment runbook
• Source of truth: doppler/src/dopplerHooks/RehypeDopplerHook.sol, doppler/src/interfaces/IRehypeHook.sol, doppler/test/invariant/rehype/SPECIFICATION.md