ci: add Rust quality checks

[lucacillario]

What changed

Add independent pull-request workflows for formatting, Clippy, and nextest. Configure Rust and Solana toolchains plus cached Cargo and Solana build artifacts.

Closes #39

Impact

Pull requests containing these workflows report all three standard Rust checks independently. The change affects CI only.

Validation

• Parsed all three workflow files as YAML.
• cargo fmt --check passed on the complete replicator stack.
• git diff --check passed.
• Clippy reached the existing Keeper SBF build locally; the installed Solana 3.0.11 platform toolchain is too old for edition 2024. CI installs Solana 4.0.3.
• Nextest is installed and exercised by the CI workflow.

Reviewer notes

This branch is stacked on replicator, the first point where the complete engine workspace exists. Existing stack branches remain unchanged.

Swatinem/rust-cache@v2 was chosen instead of sccache because it integrates directly with GitHub Actions’ persistent cache and efficiently restores Cargo dependencies and build artifacts across ephemeral runners while keeping the CI setup simpler.

[lucacillario]

• ci: add Rust quality checks #55 👈 (View in Graphite)
• feat: add state replicator crate on top of the engine #25 : 1 other dependent PR (#37 )
• feat: adds top level engine crate for global orchestration #24
• feat: added internal built-in magic root program #23
• feat: implement transaction processor crate #22
• feat: implements keeper crate - state orchestrator #17
• feat: implement superblock based ledger crate #15
• feat: add optimized accountsdb crate #14
• feat: add nucleus engine crate #18
• feat: add svm crate #21
• feat: add program runtime crate #20
• feat: add transaction context crate #19
• feat: forked transaction-view for increased limits #33
• feat: add customized solana-account crate #13
• chore: import upstream Solana runtime crates #31
• dev

This stack of pull requests is managed by Graphite. Learn more about stacking.

[coderabbitai]

📝 Walkthrough

Walkthrough

Added GitHub Actions workflows for Rust formatting, Clippy, and test checks. The workflows run on pushes and pull requests, use read-only permissions, cancel superseded runs, cache build tools, and use Rust 1.96.1.

Changes

Rust CI checks

Layer / File(s)	Summary
CI triggers and concurrency .github/workflows/ci-*.yml	The workflows run for configured pushes and pull request events. Each workflow uses read-only contents access and cancels superseded runs.
Formatting validation .github/workflows/ci-fmt.yml	The formatting job installs Rust 1.96.1 with rustfmt and runs cargo fmt --check.
Clippy validation .github/workflows/ci-lint.yml	The lint job caches Rust and Solana artifacts, installs required tooling, and runs Clippy with all features, targets, and warnings denied.
Test execution .github/workflows/ci-test.yml	The test job caches Rust and Solana artifacts, installs cargo-nextest, and runs cargo nextest run --nff.

Estimated code review effort: 2 (Simple) | ~15 minutes

Suggested reviewers: bmuddha

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the addition of Rust quality checks, which matches the primary change.
Description check	✅ Passed	The description accurately explains the three CI workflows, toolchain configuration, caching, impact, and validation.
Linked Issues check	✅ Passed	The workflows implement formatting, Clippy, and nextest checks as independent pull-request CI workflows required by issue #39.
Out of Scope Changes check	✅ Passed	The changes are limited to CI workflows and directly support the linked issue objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ci-rust-checks

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In @.github/workflows/ci-lint.yml:
- Around line 21-22: Set persist-credentials to false on the actions/checkout@v5
steps in .github/workflows/ci-lint.yml lines 21-22 and
.github/workflows/ci-test.yml lines 21-22; both checkout sites require the same
change.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 7fac5464-f35e-4b2b-a45b-1e4dffc1ddac

📥 Commits

Reviewing files that changed from the base of the PR and between d8fd7f9 and 6db70c6.

📒 Files selected for processing (3)

• .github/workflows/ci-fmt.yml
• .github/workflows/ci-lint.yml
• .github/workflows/ci-test.yml

[bmuddha]

LGTM