ci: Add pull request reviewer via gitar

[c-warren]

What changed?

Adds an initial configuration for a gitar pull request description reviewer.

Why?

This reviewer is intended to recommend improvements to a pull request description to ensure it meets our planned standards for pull requests. The goal is to help contributors and maintainers upskill their descriptions, increasing the usefulness of pull requests for release notes, future and current contributors when reviewing code.

Gitar is currently under evaluation - though we will also consider evaluating GitHub copilot.

How did you test it?

Tested via integration tests in the GitHub repository (i.e it's running on this pull request and doing it successfully!).

Potential risks

This could become distracting, overly spammy, or increase overhead for contributors/maintainers during the code review process.

We will set up a follow up meeting to evaluate its effectiveness in contributing to pull request description quality.

Release notes

N/A

Documentation Changes

Documentation should be coming with the reviewers checklist PR https://github.com/cadence-workflow/cadence/pull/7596/changes.

[gitar-bot]

Code Review ✅ Approved

Clean configuration-only PR that adds a well-structured gitar rule for automated PR description quality review. The file follows proper conventions with clear evaluation criteria, concrete examples, and pragmatic quality checks to avoid false positives.

Rules ✅ All requirements met

Repository Rules

✅ Pr Description Quality

  ✅ Documentation Changes: Acknowledges docs needs and references PR #7596
  ✅ How did you test it?: Concrete testing approach via integration tests on this PR
  ✅ Potential risks: Identifies risks and includes mitigation/evaluation plan
  ✅ Release notes: N/A is appropriate for config/internal changes
  ✅ What changed?: Clear technical summary of what was added
  ✅ Why?: Provides context, motivation, and evaluation plan

Options

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Comment with these commands to change:

Auto-apply	Compact
gitar auto-apply:on	gitar display:verbose

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[gitar-bot]

[What changed?]: Expand technical details

Details

Current: "Adds guitar rule."

Recommended: "Adds gitar rule configuration at .gitar/rules/pr-description-quality.md to automatically evaluate PR descriptions against quality standards."

The PR template guidance shows good examples include technical specifics and issue links where relevant.

[Why?]: Provide full context and motivation

Details

Current: "Needed it."

Recommended: Explain the problem being solved, the use case, and why this approach was chosen. For example:

• What problem does inadequate PR descriptions cause?
• Why use gitar for this automation?
• Why these specific evaluation criteria?
• What alternatives were considered?

The PR template emphasizes explaining WHY changes were made (see https://cbea.ms/git-commit/#why-not-how).

[How did you test it?]: Include concrete test commands

Details

Current: "N/A"

Recommended: Provide specific test commands or steps, such as:

• How was the gitar rule validated?
• Were test PRs created to verify evaluation behavior?
• Commands like testing on this PR itself

Template requires exact commands that reviewers can copy-paste to verify.

[Potential risks]: Address configuration concerns

Details

Current: "N/A"

Recommended: Consider risks such as:

• Could this rule generate false positives or be overly noisy?
• Impact on contributor experience?
• Can it be easily disabled if issues arise?
• Any performance concerns with automated evaluation?

[gitar-bot]

✅ PR description meets quality standards.

The updated description successfully addresses all required sections:

• Clear technical summary of what changed
• Context and motivation for the change
• Concrete testing approach (integration tests on this PR)
• Risk identification with mitigation plan
• Appropriate documentation references