feat: Add GovernorDelay extension for simple proposal delays

[avorylli]

Implements issue #6052 by adding a simple way to enforce delays on all proposals without requiring external timelock contracts.

Changes

• Add GovernorDelay extension that enforces a configurable delay on all proposals
• Delay is enforced by the Governor itself (unlike GovernorTimelockControl which uses external timelock)
• Delay uses block.timestamp (seconds) regardless of governor's clock mode
• Delay can be updated through governance proposals

Testing

• 20 tests covering all scenarios
• Tests pass for both blocknumber and timestamp clock modes

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Latest commit: 0f5d744

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[coderabbitai]

Walkthrough

A new GovernorDelay governance extension is introduced that adds a configurable execution delay to proposals. The extension includes state management for delay duration, governance-controlled delay modification, queuing requirement detection when delay is active, ETA calculation during queuing, and execution-time delay enforcement with error handling. Supporting files include documentation updates, a mock contract for testing, and comprehensive test coverage validating deployment, delay configuration, queuing behavior, execution timing, and error scenarios across both blocknumber and timestamp voting modes.

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'feat: Add GovernorDelay extension for simple proposal delays' accurately reflects the main change: introducing a new GovernorDelay extension for proposal delays.
Description check	✅ Passed	The description is directly related to the changeset, clearly explaining the GovernorDelay extension purpose, key features, and testing approach.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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Actionable comments posted: 0

🧹 Nitpick comments (1)

test/governance/extensions/GovernorDelay.test.js (1)

302-355: Consider adding edge case: proposals with identical operations.

The multiple proposals test uses different descriptions ('descr1' vs 'descr2') to differentiate proposals. Consider adding a comment or an additional test case that explicitly verifies behavior when proposals have identical targets/values/calldatas but different descriptions, to document that uniqueness comes from the description hash.

📜 Review details

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 353f564 and 0f5d744.

📒 Files selected for processing (4)

• contracts/governance/README.adoc (2 hunks)
• contracts/governance/extensions/GovernorDelay.sol (1 hunks)
• contracts/mocks/governance/GovernorDelayMock.sol (1 hunks)
• test/governance/extensions/GovernorDelay.test.js (1 hunks)

🧰 Additional context used

🧠 Learnings (1)

📚 Learning: 2025-08-29T13:16:08.640Z

Learnt from: Amxx
Repo: OpenZeppelin/openzeppelin-contracts PR: 5904
File: contracts/mocks/crosschain/ERC7786RecipientMock.sol:12-14
Timestamp: 2025-08-29T13:16:08.640Z
Learning: In OpenZeppelin contracts, mock contracts (like ERC7786RecipientMock) don't require input validation such as zero-address checks in constructors, as they are only used for testing purposes in controlled environments.

Applied to files:

• contracts/mocks/governance/GovernorDelayMock.sol

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (9)

• GitHub Check: tests
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🔇 Additional comments (5)

contracts/governance/extensions/GovernorDelay.sol (1)

1-105: LGTM! Well-structured governance delay extension.

The implementation is clean and follows OpenZeppelin patterns:

• Event emission before state mutation follows Checks-Effects-Interactions pattern
• The uint32 delay type provides sufficient range (~136 years) while being gas-efficient
• Proper use of SafeCast and Time utilities
• Clear documentation about timestamp-based delays regardless of clock mode

contracts/governance/README.adoc (2)

39-40: LGTM! Documentation accurately describes the extension.

The documentation correctly positions GovernorDelay as a simpler alternative to external timelocks and clearly explains that the delay is enforced by the Governor itself.

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91-92: API entry correctly placed.

contracts/mocks/governance/GovernorDelayMock.sol (1)

11-50: LGTM! Proper resolution of multiple inheritance conflicts.

The override declarations correctly resolve the diamond inheritance pattern by delegating to super, which follows the C3 linearization order. Based on learnings, mock contracts don't require additional validation as they're only used for testing purposes.

test/governance/extensions/GovernorDelay.test.js (1)

25-357: Comprehensive test coverage for GovernorDelay.

The test suite thoroughly covers:

• Deployment verification
• Governance-controlled delay modification with access control check
• Zero vs non-zero delay queuing behavior
• ETA calculation and enforcement
• State transitions through the proposal lifecycle
• Multiple concurrent proposals with independent ETAs

Testing both blocknumber and timestamp token modes ensures the extension works correctly regardless of clock mode, which aligns with the documented behavior.