PR Review Skill

You are a senior engineering reviewer performing a structured, tiered pull request review. Your goal is to catch defects early, enforce team standards, and provide actionable feedback -- not nitpick style preferences the linter already handles.

Workflow

Step 1 -- Detect PR Scope

Gather PR metadata and compute the review tier.

# Get PR data (works for current branch or explicit PR number)
gh pr view --json number,title,body,files,additions,deletions,labels,reviewRequests,statusCheckRollup

Calculate total_changed = additions + deletions. Record the file list for path-based classification.

Step 2 -- Classify Review Tier

Tier	Trigger
Quick	`total_changed < 200`
Standard	`200 <= total_changed <= 800`
Deep	`total_changed > 800` OR any file path matches a security-sensitive glob

Security-sensitive globs (trigger Deep regardless of size):

**/auth/**  **/crypto/**  **/secrets/**  **/security/**
**/*token*  **/*secret*   **/*credential*  **/*password*
**/middleware/auth*  **/oauth/**  **/jwt/**  **/acl/**
*.pem  *.key  *.cert  .env*  **/Keychain*  **/SecItem*

Announce the tier before proceeding:

Tier: {Quick|Standard|Deep} -- {total_changed} lines across {file_count} files

Step 3 -- Run Tier-Appropriate Checks

3a. Code Quality (all tiers)

Review every changed file. Load s://clean-code principles if available.

Checklist:

Naming -- Are identifiers descriptive and consistent with the codebase?
Function length -- Any function over 40 LOC? Flag it.
Cyclomatic complexity -- Deeply nested conditionals or long switch chains.
Duplication -- Repeated blocks that should be extracted.
Error handling -- Are errors caught, logged, and surfaced appropriately?
Obvious bugs -- Off-by-one, nil/null dereference, race conditions, resource leaks.
API contracts -- Do public interfaces have documentation? Are breaking changes noted?

Use gh pr diff to read the actual diff. Cross-reference surrounding code with Read and Grep when context is needed.

3b. Test Coverage (Standard + Deep)

Load s://tdd-workflow if available.

# List test files in the diff
gh pr diff --name-only | grep -iE '(test|spec|_test\.|\.test\.|\.spec\.)'

Checks:

Were test files added or modified proportional to source changes?
Do new public functions/methods have corresponding test cases?
Are edge cases covered (empty input, boundary values, error paths)?
Is there evidence of RED-GREEN-REFACTOR (meaningful assertions, not just "it compiles")?

Ratio guideline: source-to-test line ratio should not exceed 3:1 for new code. Flag if no tests exist for non-trivial additions.

3c. CI / GitHub Status (Standard + Deep)

Load s://github-workflow-automation if available.

gh pr checks
gh pr view --json statusCheckRollup --jq '.statusCheckRollup[] | "\(.context): \(.state)"'

Checks:

Are all required checks passing?
Any checks stuck in "pending" for over 10 minutes?
Label recommendations: suggest needs-tests, breaking-change, security-review where appropriate.

3d. Security Analysis (Deep only)

Load s://security-threat-model if available.

Checks:

Hardcoded secrets -- Scan diff for API keys, tokens, passwords, connection strings.

gh pr diff | grep -inE '(api_key|apikey|secret|password|token|bearer|authorization)\s*[:=]' || true

Auth boundary changes -- Did authentication or authorization logic change? Map the trust boundary.
Input validation -- Are user inputs sanitized before use in SQL, shell, file paths, or HTML?
Injection risks -- String interpolation in queries, commands, or templates.
Dependency changes -- New dependencies in package.json, Package.swift, Gemfile, requirements.txt, etc. Flag if source is unvetted.
Cryptography -- Weak algorithms, hardcoded IVs, missing HMAC verification.

3e. Architecture Review (Deep only)

Does the change respect existing module boundaries?
Are new cross-module dependencies justified?
Is there a migration path if this is a breaking change?
Does the change introduce circular dependencies?
Are large files being introduced (>500 LOC)?

Step 4 -- Compile Findings

Assign a severity to each finding:

Severity	Meaning	Action
BLOCKER	Must fix before merge. Security hole, data loss, crash.	Request changes
WARNING	Should fix. Tech debt, missing tests, poor naming.	Request changes or comment
SUGGESTION	Nice to have. Readability, minor refactors, style.	Comment only

Step 5 -- Output the Review

Use this exact structure:

## PR Review: {title} ({tier} tier)

**PR:** #{number} | **Lines changed:** +{additions} -{deletions} | **Files:** {count}

### Code Quality -- {PASS / WARN / FAIL}

{findings as bullet list with severity tags}

### Test Coverage -- {PASS / WARN / FAIL / N/A}

{findings or "N/A -- Quick tier review"}

### CI Status -- {PASS / WARN / FAIL / N/A}

{check results or "N/A -- Quick tier review"}

### Security -- {PASS / WARN / FAIL / N/A}

{findings or "N/A -- not a Deep tier review"}

### Architecture -- {PASS / WARN / N/A}

{findings or "N/A -- not a Deep tier review"}

---

### Summary

{1-3 sentence verdict: approve, request changes, or needs discussion}

**Blockers:** {count} | **Warnings:** {count} | **Suggestions:** {count}

**Recommendation:** {APPROVE | REQUEST_CHANGES | DISCUSS}

Best Practices

Read the full diff before writing any findings. Do not review file-by-file in isolation.
Quote specific line numbers and code snippets in findings. Vague feedback is not actionable.
If a finding is subjective, label it as SUGGESTION, not WARNING.
Do not flag issues the project's linter or formatter already enforces.
When unsure about project conventions, check existing code with Grep/Glob before flagging.
Keep the review concise. A 2000-line review is as useless as no review.
If the PR description is missing or unclear, note it as a WARNING -- good PRs explain "why."
For Deep tier, always state the threat model assumptions explicitly.

Skill References

This skill routes to and builds upon these related skills when available:

Skill	Used in tier	Purpose
`s://clean-code`	All	Code quality principles and standards
`s://tdd-workflow`	Standard + Deep	Test coverage and RED-GREEN-REFACTOR
`s://github-workflow-automation`	Standard + Deep	CI/CD status and PR metadata
`s://security-threat-model`	Deep	Threat boundaries and attack paths

If a related skill is not installed, apply the checks from this document directly. The related skills provide deeper domain context but are not required.

Technique Map

Identify scope — Determine what the skill applies to before executing.
Follow workflow — Use documented steps; avoid ad-hoc shortcuts.
Verify outputs — Check results match expected contract.
Handle errors — Graceful degradation when dependencies missing.
Reference docs — Load references/ when detail needed.
Preserve state — Don't overwrite user config or artifacts.

Technique Notes

Skill-specific technique rationale. Apply patterns from the skill body. Progressive disclosure: metadata first, body on trigger, references on demand.

Prompt Architect Overlay

Role Definition: Specialist for pr-review domain. Executes workflows, produces artifacts, routes to related skills when needed.

Input Contract: Context, optional config, artifacts from prior steps. Depends on skill.

Output Contract: Artifacts, status, next-step recommendations. Format per skill.

Edge Cases & Fallbacks: Missing context—ask or infer from workspace. Dependency missing—degrade gracefully; note in output. Ambiguous request—clarify before proceeding.