pr-review-expert

PR Review Expert

Structured, systematic code review for GitHub PRs and GitLab MRs. Goes beyond style nits to perform blast-radius analysis, security vulnerability scanning, breaking-change detection, test-coverage delta calculation, and performance impact assessment. Produces reviewer-ready reports with prioritized findings categorized as must-fix, should-fix, and suggestions.

Keywords: PR review, code review, pull request, merge request, blast radius, security scan, breaking changes, test coverage, review checklist, code quality

Core Capabilities

• Blast radius analysis — trace which files, services, and downstream consumers a diff could break; quantify severity CRITICAL/HIGH/MEDIUM/LOW.
• Security scanning — detect SQL injection, XSS vectors, hardcoded secrets, auth bypass, insecure crypto, path traversal, and prototype pollution in the diff.
• Breaking-change detection — flag API removals/renames, response-schema and required-field changes, DB column removals, env-var changes, and TS interface edits.
• Test coverage analysis — new-code vs new-test ratio, missing tests for new public functions, deleted tests without deleted code, coverage delta.
• Performance assessment — N+1 query patterns, bundle-size regressions, unbounded queries, missing indexes.
• Reviewer-ready output — prioritized must-fix / should-fix / suggestion report, a 35-item checklist, and consistent comment labels.

When to Use

• Before merging any PR that touches shared libraries, APIs, or database schemas.
• When a PR is large (>200 lines changed) and needs structured review.
• For PRs in security-sensitive code paths (auth, payments, PII handling).
• After an incident, to proactively review similar code changes.
• For onboarding new contributors whose PRs need thorough feedback.

Clarify First

Before reviewing, settle the inputs below. When one is missing or vague and would change the result, ask about it; when it wouldn't, use a sensible default and say which one you used.

• Which PR and base branch: blast radius and coverage deltas are computed against the base; a stale base reports changes that aren't in the PR.
• What the change is for: (linked ticket or one-line intent) — without it, intended behaviour changes get flagged as bugs.
• Review depth: a full blast-radius and security pass, or a quick check of a small change — sets which workflow steps run.

Ask about the two or three inputs that matter most for this request. If the user says "just review it," proceed and state your assumptions at the top of the report.

Tools

Tool	Purpose	Command
blast_radius_calculator.py	Calculate PR blast radius from import chains / dependency trees of changed files	git diff --name-only main...HEAD | python scripts/blast_radius_calculator.py --root src
diff_analyzer.py	Analyze a diff for risk indicators (large files, sensitive paths, config/breaking/security patterns)	gh pr diff $PR | python scripts/diff_analyzer.py --json
review_checklist_generator.py	Generate a tailored review checklist from changed file types/patterns	git diff --name-only main...HEAD | python scripts/review_checklist_generator.py

Anti-Patterns

Reviewing style instead of substance

Mistake: Most comments are about naming and formatting. Why it happens: Style problems are visible on a first read; logic and security problems need context. Instead: Leave formatting to the linter. Spend the review on blast radius, security, correctness and error paths, and label every comment must:, nit: or question:.

Judging risk by diff size

Mistake: A five-line change to a shared utility is approved because it is five lines. Why it happens: The diff size is the only risk measure on the screen. Instead: Run blast_radius_calculator.py on the changed files. A small change in a shared module can break every service that imports it.

Approving an untested happy path

Mistake: The PR only tests the success case. Why it happens: The tests pass and the coverage number looks fine. Instead: Check that error paths and edge cases have tests, and flag any new public function that has none.

More pitfalls and the troubleshooting table: references/best-practices-and-troubleshooting.md.

References

Load the reference that matches the task — keep this file lean and pull detail on demand:

• references/review-workflow-commands.md — the 6-step review workflow with the exact gh/grep command catalog for context gathering, blast radius, security scan, breaking-change detection, coverage delta, and performance impact (plus the blast-radius severity table and coverage rules). Read when actually performing a review.
• references/writeup-format-and-checklist.md — the review report template with worked examples, the complete 35-item review checklist, and the comment-label taxonomy. Read when writing up findings.
• references/best-practices-and-troubleshooting.md — common reviewer pitfalls, best-practice habits, the troubleshooting table, and the success-criteria bar. Read before and after a review for quality control.

Scope & Limitations

This skill covers:

• Structured review of GitHub PRs and GitLab MRs using a 35+ item checklist
• Blast radius analysis for monorepo and multi-service architectures
• Static security scanning of diffs for common vulnerability patterns (SQLi, XSS, secrets, auth bypass)
• Breaking change detection for APIs, database schemas, TypeScript interfaces, and environment variables

This skill does NOT cover:

• Automated code fixes or refactoring — use engineering/saas-scaffolder or engineering/migration-architect for code generation
• Runtime security analysis, SAST/DAST tool orchestration, or CVE database lookups — use engineering/dependency-auditor for dependency-level vulnerability scanning
• CI/CD pipeline configuration or build failure triage — use engineering/ci-cd-pipeline-builder for pipeline design
• Performance benchmarking or load testing — use engineering/performance-profiler for profiling and optimization guidance

Integration Points

Skill	Integration	Data Flow
engineering/dependency-auditor	Run dependency audit before reviewing PRs that add or upgrade packages	Audit report feeds into the Security section of the review report
engineering/ci-cd-pipeline-builder	Embed review checklist gates into CI pipelines as automated PR checks	Checklist items become pass/fail signals in the pipeline
engineering/performance-profiler	Escalate N+1 and unbounded query findings for detailed profiling	Flagged code paths from review become profiling targets
engineering/migration-architect	Validate database migration safety for PRs that include schema changes	Migration risk assessment supplements the Breaking Changes section
engineering/release-manager	Feed breaking change detection results into release notes and changelogs	Detected breaking changes auto-populate release documentation
engineering/api-design-reviewer	Cross-reference API endpoint changes with API design standards	API review findings merge into the Blast Radius and Breaking Changes sections