Validate participant roles in IsValidEpochSetup

[zhangchiqing]

Problem

IsValidEpochSetup already checked that an EpochSetup has enough active nodes for each known role, but it never rejected participants whose Role field was not a valid flow.Role. An invalid role (e.g. 0 or 42) would be accepted as long as the real roles were still represented, and later code paths that call Role.String() would panic on the bogus value.

Changes

• Add a defense-in-depth check that calls Role.Valid() for every participant and rejects the setup with an error if any participant has an invalid role.
• Add a regression test that mutates a consensus participant to an invalid role and asserts that IsValidEpochSetup returns an error.

Labels: Bug, S-Epochs

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Summary by CodeRabbit

• Bug Fixes
  • Epoch setup validation now rejects participants with invalid roles.
  • Validation errors identify the invalid role and associated node.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Team

Run ID: 59c5a616-69ca-4285-9ce0-47cfe0b375bd

📥 Commits

Reviewing files that changed from the base of the PR and between 2a03353 and 653159e.

📒 Files selected for processing (2)

• state/protocol/validity.go
• state/protocol/validity_test.go

Included review availability: Your plan provides up to 4 included reviews per hour; 2 remain after this review.

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📝 Walkthrough

Walkthrough

Epoch setup validation now checks that every participant has a valid role. A test sets a participant role to flow.Role(42) and verifies that validation returns an error.

Changes

Epoch setup validation

Layer / File(s)	Summary
Participant role validation state/protocol/validity.go, state/protocol/validity_test.go	IsValidEpochSetup rejects participants with invalid roles and reports the role and node ID. The validity test covers an invalid consensus participant role.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 65315

Epoch setups with invalid participant roles are now rejected before later role handling can fail, with regression coverage for the invalid-role case. No current merge-blocking risk remains.

Suggested reviewers: alexhentschel, j1010001, janezpodhostnik

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: validating participant roles in IsValidEpochSetup.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch leo/validate-epoch-setup-participant-roles

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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