feat: add fee distributor

[johnletey]

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Summary by CodeRabbit

• New Features
  • Introduced fee distribution system enabling multiple recipients to receive fees based on configurable allocation percentages.
  • Added fee recipient functionality to validators, allowing fee recipient addresses to be set and updated.
  • Implemented fee distribution mechanism that proportionally distributes native balance to recipients with remainder handling for block proposers.

[coderabbitai]

📝 Walkthrough

Walkthrough

The changes introduce a fee distribution system by adding a FeeDistributor contract address constant, defining a new IFeeDistributor interface for managing fee recipients and distributing native balance proportionally to them, and extending IValidatorManager to support fee recipient configuration per validator.

Changes

Cohort / File(s)	Summary
Fee Distributor Infrastructure src/Constants.sol, src/interfaces/IFeeDistributor.sol	Adds FEE_DISTRIBUTOR_ADDRESS constant and introduces IFeeDistributor interface with recipient management (set/remove/query), distribute function, and supporting structs, events, and errors.
Validator Fee Recipient Support src/interfaces/IValidatorManager.sol	Extends Validator, ValidatorInfo, and GenesisValidator structs with feeRecipient field; modifies addValidator signature to include feeRecipient parameter; adds setFeeRecipient and getFeeRecipient functions; introduces FeeRecipientUpdated event and Unauthorized error.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested reviewers

• keyleu

Poem

🐰 Hopping through code, a new path we trace,
Fee distributors in their rightful place,
Validators wear their recipient hats,
Sharing the rewards where the balance sits,
A carrot-filled update, crisp and precise! 🥕

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: add fee distributor' directly aligns with the main changes in the pull request, which introduce a new FeeDistributor interface and related functionality across Constants, IFeeDistributor, and IValidatorManager.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/fee-distributor

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 3 additional findings.

[coderabbitai]

🧹 Nitpick comments (1)

src/interfaces/IFeeDistributor.sol (1)

50-53: Consider documenting zero address behavior.

The interface doesn't specify whether address(0) is a valid recipient. If the implementation should reject zero addresses, consider adding an InvalidRecipient error and documenting this constraint in the NatSpec.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/interfaces/IFeeDistributor.sol` around lines 50 - 53, The interface lacks
guidance on zero-address handling for recipients; add a custom error (e.g.,
InvalidRecipient()) to IFeeDistributor and update the NatSpec on
setRecipient(address recipient, uint16 bps) to state that address(0) is
disallowed, and require implementations to revert with InvalidRecipient when
recipient == address(0); include the error symbol (InvalidRecipient) and the
setRecipient function name in the docs so implementers enforce and emit that
specific revert for invalid (zero) recipients.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@src/interfaces/IFeeDistributor.sol`:
- Around line 50-53: The interface lacks guidance on zero-address handling for
recipients; add a custom error (e.g., InvalidRecipient()) to IFeeDistributor and
update the NatSpec on setRecipient(address recipient, uint16 bps) to state that
address(0) is disallowed, and require implementations to revert with
InvalidRecipient when recipient == address(0); include the error symbol
(InvalidRecipient) and the setRecipient function name in the docs so
implementers enforce and emit that specific revert for invalid (zero)
recipients.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 2a8bfba7-a7ae-4789-ade8-6622fd737cbe

📥 Commits

Reviewing files that changed from the base of the PR and between 9926ad3 and 9bd3f09.

📒 Files selected for processing (3)

• src/Constants.sol
• src/interfaces/IFeeDistributor.sol
• src/interfaces/IValidatorManager.sol