AI code reviews grounded in twelve classic engineering books.
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The Six Decay Risks • What It Looks Like • Benchmark • Installation

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"The bearing of a child takes nine months, no matter how many women are assigned." — Frederick Brooks, The Mythical Man-Month (1975)

50 years later, Brooks was still right — and so were McConnell, Fowler, Martin, Hunt & Thomas, Evans, Ousterhout, Winters, Meszaros, Osherove, Feathers, and the Google Testing team.

Most code quality tools count lines and cyclomatic complexity. brooks-lint goes deeper — it diagnoses your code against six decay risk dimensions synthesized from twelve classic engineering books, producing structured findings with book citations, severity labels, and concrete remedies every time.

For the full source-to-skill mapping, including exceptions and false-positive guards, see skills/_shared/source-coverage.md.

The Twelve Books

The Six Decay Risks

brooks-lint evaluates your code across six production-code decay risks and six test-suite decay risks synthesized from twelve classic engineering books:

Philosophy of SD = A Philosophy of Software Design (Ousterhout) · SE@Google = Software Engineering at Google (Winters et al.)

What It Looks Like

Given this code:

class UserService:
    def update_profile(self, user_id, name, email, avatar_url):
        user = self.db.query(f"SELECT * FROM users WHERE id = {user_id}")
        user['email'] = email
        ...
        if user['email'] != email:   # always False — silent bug
            self.smtp.send(...)
        points = user['login_count'] * 10 + 500
        self.db.execute(f"UPDATE loyalty SET points={points} WHERE user_id={user_id}")

brooks-lint produces:

Health Score: 28/100

This method concentrates four unrelated business responsibilities into a single function, contains a logic bug that silently suppresses email change notifications, and is wide open to SQL injection.

🔴 Change Propagation — Single Method Changes for Four Unrelated Business Reasons

Symptom: update_profile performs profile field updates, email change notifications, loyalty points recalculation, and cache invalidation all in one method body. Source: Fowler — Refactoring — Divergent Change; Hunt & Thomas — The Pragmatic Programmer — Orthogonality Consequence: Any change to the loyalty formula risks breaking email notifications and vice versa. Every edit carries regression risk across four unrelated domains simultaneously. Remedy: Extract NotificationService, LoyaltyService, and UserCacheInvalidator. UserService.update_profile should orchestrate by calling each — it should hold no implementation logic itself.

🔴 Domain Model Distortion — Silent Logic Bug: Email Notification Never Fires

Symptom: user['email'] = email overwrites the old value before if user['email'] != email — the condition is always False. The notification is dead code. Source: McConnell — Code Complete — Ch. 17: Unusual Control Structures Consequence: Users are never notified when their email address changes. Silent data integrity failure — the system appears functional while violating a business rule. Remedy: Capture old_email = user['email'] before any mutation. Compare against old_email, not user['email'].

(+ 6 more findings including SQL injection, dependency disorder, magic numbers)

Architecture Audit with Dependency Graph

In Mode 2 (Architecture Audit), brooks-lint generates a Mermaid dependency graph at the top of the report. Modules are color-coded by severity: red = Critical findings, yellow = Warning, green = clean.

graph TD
    subgraph src/api
        AuthController
        UserController
    end
    subgraph src/domain
        UserService
        OrderService
    end
    subgraph src/infra
        Database
        EmailClient
    end

    AuthController --> UserService
    UserController --> UserService
    UserController --> OrderService
    OrderService --> UserService
    OrderService --> EmailClient
    UserService --> Database
    EmailClient -.->|circular| OrderService

    classDef critical fill:#ff6b6b,stroke:#c92a2a,color:#fff
    classDef warning fill:#ffd43b,stroke:#e67700
    classDef clean fill:#51cf66,stroke:#2b8a3e,color:#fff

    class OrderService,EmailClient critical
    class AuthController warning
    class UserService,UserController,Database clean

The graph renders natively in GitHub, Notion, and other Markdown environments — no extra tools needed.

See More Examples

The Full Gallery has real brooks-lint output across Python, TypeScript, Go, and Java — including PR reviews, architecture audits with Mermaid dependency graphs, tech debt assessments, and test quality reviews.

New to the decay risks? The Decay Risk Field Guide explains all six — diagnostic question, signature symptoms, source books, and remedy for each.

Benchmark

Tested across 3 real-world scenarios (PR review, architecture audit, tech debt assessment):

The gap isn't what Claude can find — it's what it consistently finds, with traceable evidence and actionable remedies every time.

How It Compares

~ = occasionally / inconsistently

brooks-lint doesn't replace your linter. It catches what linters can't: architectural drift, knowledge silos, and domain model distortion — the problems that slow teams down for months before anyone notices.

Installation

Claude Code (Recommended)

Via Plugin Marketplace

/plugin marketplace add hyhmrright/brooks-lint
/plugin install brooks-lint@brooks-lint-marketplace

Short-form commands (/brooks-review) are auto-installed on first session start. To install manually:

cp commands/*.md ~/.claude/commands/

Manual Install

mkdir -p ~/.claude/skills/brooks-lint
cp -r skills/* ~/.claude/skills/brooks-lint/

Gemini CLI

Via Extension

/extensions install https://github.com/hyhmrright/brooks-lint

Manual Install

mkdir -p ~/.gemini/skills
cp -r skills/* ~/.gemini/skills/      # flat — Gemini discovers skills only one level deep

Or simply: ./scripts/install.sh gemini

Codex CLI

Via Skill Installer (in Codex session)

Install the brooks-lint skill from hyhmrright/brooks-lint

Command Line

python3 ~/.codex/skills/.system/skill-installer/scripts/install-skill-from-github.py \
  --repo hyhmrright/brooks-lint --path skills --name brooks-lint

Manual Install

git clone https://github.com/hyhmrright/brooks-lint.git /tmp/brooks-lint
mkdir -p ~/.codex/skills
cp -r /tmp/brooks-lint/skills/* ~/.codex/skills/   # flat — matches the skill-installer layout

Or simply: ./scripts/install.sh codex

More platforms — OpenCode · Cursor · Windsurf · Antigravity · pi · Copilot · Kiro · Factory Droid

brooks-lint ships as standard Agent Skills. Any agent that loads Agent Skills runs all six modes with no conversion — one command installs them:

# pick your platform; --project installs into the current repo instead of your global config
curl -fsSL https://raw.githubusercontent.com/hyhmrright/brooks-lint/main/scripts/install.sh | bash -s -- <platform>
#   <platform> = opencode · cursor · windsurf · antigravity · pi · kiro · copilot · droid · gemini · codex · agents

The installer copies the skills flat into the right folder for your platform, so the shared framework (../_shared/) always resolves — you can't get the layout wrong. Then just ask ("review this PR", "audit the architecture") and the matching skill auto-triggers from its description. New to skills, or using another agent? See docs/getting-started.md.

🧪 Verification status. Claude Code, Gemini CLI, and Codex CLI are maintainer-verified. The eight platforms above are documented from each tool's official skill spec and verified at the file-layout level (the installer is tested), but not yet end-to-end run by the maintainer on every platform. Tried one — working or broken? Open an issue with the platform, version, and what you saw. Another Agent-Skills agent? It almost certainly works the same way — tell us and we'll add it.

Slash Commands

Claude Code

Short-form commands are auto-installed on first session start by the session-start hook.

Gemini CLI

Codex CLI

The skills also trigger automatically when you discuss code quality, architecture, maintainability, or test health.

OpenCode · Cursor · Antigravity · pi

These platforms invoke Agent Skills automatically from each skill's description — just ask ("review this PR", "audit the architecture", "where's our worst tech debt?") and the matching mode runs. For explicit invocation, use the platform's skill-command syntax (e.g. pi registers each skill as /skill:brooks-review; Cursor and OpenCode expose /brooks-review once the skill is discovered).

Usage

PR Review

/brooks-review                      # Claude Code (short form) / Gemini CLI
/brooks-lint:brooks-review          # Claude Code (full form)
$brooks-review                      # Codex CLI

Paste a diff or point the AI at changed files. Diagnoses each of the six decay risks with specific findings in Symptom → Source → Consequence → Remedy format.

Architecture Audit

/brooks-audit                       # Claude Code (short form) / Gemini CLI
/brooks-lint:brooks-audit           # Claude Code (full form)
$brooks-audit                       # Codex CLI

Describe your project structure or share key files. It maps module dependencies, identifies circular dependencies, and checks Conway's Law alignment.

Tech Debt Assessment

/brooks-debt                        # Claude Code (short form) / Gemini CLI
/brooks-lint:brooks-debt            # Claude Code (full form)
$brooks-debt                        # Codex CLI

Classifies your debt across the six decay risks, scores each finding by Pain × Spread priority, and produces a prioritized repayment roadmap with Critical / Scheduled / Monitored classification.

Test Quality Review

/brooks-test                        # Claude Code (short form) / Gemini CLI
/brooks-lint:brooks-test            # Claude Code (full form)
$brooks-test                        # Codex CLI

Audits your test suite against six test-space decay risks — Test Obscurity, Test Brittleness, Test Duplication, Mock Abuse, Coverage Illusion, and Architecture Mismatch — sourced from xUnit Test Patterns, The Art of Unit Testing, How Google Tests Software, and Working Effectively with Legacy Code. PR reviews also include a lightweight Step 7 Quick Test Check automatically (skipped for docs-only or non-production diffs).

Health Dashboard

/brooks-health                      # Claude Code (short form) / Gemini CLI
/brooks-lint:brooks-health          # Claude Code (full form)
$brooks-health                      # Codex CLI

Runs abbreviated scans across all four quality dimensions and produces a weighted composite Health Score (0–100). Use it before a release, when onboarding a new team, or whenever you want a big-picture "how are we doing?" report. For deeper diagnosis on any dimension, use the focused skill instead.

Full Sweep

/brooks-sweep                       # Claude Code (short form) / Gemini CLI
/brooks-lint:brooks-sweep           # Claude Code (full form)
$brooks-sweep                       # Codex CLI

Runs a unified scan across all production (R1–R6) and test (T1–T6) decay risks plus architecture in a single pass, then applies fixes: safe changes are auto-applied immediately, multi-file or interface-touching changes require confirmation, and complex architectural decisions are flagged as manual items. Outputs a Fix Log, Health Score delta, and a residual item list.

Configuration

Place a .brooks-lint.yaml in your project root to customize review behavior:

version: 1

disable:
  - T5   # skip coverage metrics check — we don't enforce coverage

severity:
  R1: suggestion   # downgrade Cognitive Overload findings for this domain

ignore:
  - "**/*.generated.*"
  - "**/vendor/**"

Copy .brooks-lint.example.yaml as a starting point. All settings are optional — omit the file entirely for default behavior.

Why These Books, Why Now?

In the age of AI-assisted coding, we're writing more code faster than ever. But the insights from six decades of software engineering haven't changed:

"The complexity of software is an essential property, not an accidental one." — Frederick Brooks

AI can help you write code faster, but it can't tell you whether you're building a cathedral or a tar pit. brooks-lint bridges that gap — it brings the hard-won wisdom of twelve classic engineering books into your modern development workflow.

The decay risks these authors identified are more relevant than ever:

• Adding AI assistants doesn't fix cognitive overload or domain model distortion
• Generating more code increases change propagation and knowledge duplication
• Moving faster makes accidental complexity and dependency disorder even more dangerous

Project Structure

brooks-lint/
├── .claude-plugin/              # Claude Code plugin metadata
├── .codex-plugin/               # Codex CLI plugin metadata
├── skills/
│   ├── _shared/                 # Shared framework files
│   │   ├── common.md            # Iron Law, Project Config, Report Template, Health Score
│   │   ├── source-coverage.md   # 12-book coverage matrix, tradeoffs, false-positive guards
│   │   ├── decay-risks.md       # Six decay risks with symptoms and book citations
│   │   ├── test-decay-risks.md  # Six test-space decay risks with book citations
│   │   ├── remedy-guide.md      # --fix mode: actionable Remedy enhancement rules
│   │   └── custom-risks-guide.md  # Template for project-specific risk codes
│   ├── brooks-review/           # Mode 1: PR Review
│   │   ├── SKILL.md
│   │   └── pr-review-guide.md
│   ├── brooks-audit/            # Mode 2: Architecture Audit
│   │   ├── SKILL.md
│   │   └── architecture-guide.md
│   ├── brooks-debt/             # Mode 3: Tech Debt Assessment
│   │   ├── SKILL.md
│   │   └── debt-guide.md
│   ├── brooks-test/             # Mode 4: Test Quality Review
│   │   ├── SKILL.md
│   │   └── test-guide.md
│   ├── brooks-health/           # Mode 5: Health Dashboard
│   │   ├── SKILL.md
│   │   └── health-guide.md
│   └── brooks-sweep/            # Mode 6: Full Sweep & Auto-Fix
│       ├── SKILL.md
│       └── sweep-guide.md
├── hooks/                       # SessionStart hook
├── commands/                    # Short-form command wrappers (auto-installed by hook)
├── evals/                       # Benchmark test cases
│   └── evals.json
└── assets/
    └── logo.svg

CI/CD Integration

Automate brooks-lint on every PR using the GitHub Action:

# .github/workflows/brooks-lint.yml
name: Brooks-Lint PR Review
on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  brooks-lint:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: hyhmrright/brooks-lint/.github/actions/brooks-lint@main
        with:
          mode: review
          anthropic-api-key: ${{ secrets.ANTHROPIC_API_KEY }}
          fail-below: 70

See docs/github-action-example.yml for the full template.

The action posts the review as a PR comment and optionally fails the check if the Health Score drops below a threshold. If .brooks-lint-history.json is committed to your repo, the comment also includes a trend delta (e.g., "85 → 82 (−3) over last 3 runs").

Cost: ~$0.05–0.15 per PR run depending on diff size and model. Recommend running on pull_request events only.

Roadmap

Current state (v1.0): 12-book foundation, 6 production decay risks (R1–R6) + 6 test decay risks (T1–T6), 5 skills — PR Review, Architecture Audit, Tech Debt, Test Quality, Health Dashboard. Earlier entries below describe historical milestones, not the current feature set.

• v0.2: Plugin infrastructure (.claude-plugin/, hooks, slash commands)
• v0.3: Eight Brooks dimensions, documentation completeness scoring
• v0.4: Six-book framework, decay risk dimensions, diagnosis chain, benchmark suite
• v0.5: Test Quality Review (Mode 4) — four testing books, six test decay risks
• v0.6: Mermaid dependency graph in Architecture Audit
• v0.7: .brooks-lint.yaml project config, Mode 2 proactive context, 10-book expansion
• v0.8: Independent skill architecture with namespaced commands
• v0.9: Step validation, auto-diff scope, /brooks-health dashboard, trend tracking, triage mode, --fix remedies, onboarding report, GitHub Action
• v1.0: Eval automation (run-evals-live.mjs), custom risk extension (Cx codes)

Want to help? The best contributions right now are new eval test cases and improved decay risk symptom patterns. See CONTRIBUTING.md.

Contributing

See CONTRIBUTING.md for how to add findings, improve guides, or expand the benchmark suite.

Run /brooks-review on your own PR — we review contributions with the tool we're building.

License

MIT License — see LICENSE for details.

Acknowledgments

This project stands on the shoulders of twelve giants:

Production Code Framework

• Frederick P. Brooks Jr. — The Mythical Man-Month (1975, Anniversary Edition 1995)
• Steve McConnell — Code Complete (1993, 2nd ed. 2004)
• Martin Fowler — Refactoring (1999, 2nd ed. 2018)
• Robert C. Martin — Clean Architecture (2017)
• Andrew Hunt & David Thomas — The Pragmatic Programmer (1999, 20th Anniversary Ed. 2019)
• Eric Evans — Domain-Driven Design (2003)
• John Ousterhout — A Philosophy of Software Design (2018)
• Titus Winters, Tom Manshreck, and Hyrum Wright — Software Engineering at Google (2020)

Test Quality Framework

• Gerard Meszaros — xUnit Test Patterns (2007)
• Roy Osherove — The Art of Unit Testing (2009, 3rd ed. 2023)
• Google Engineering — How Google Tests Software (2012)
• Michael Feathers — Working Effectively with Legacy Code (2004)

The decay risks encoded in this tool are our synthesis of their ideas, applied to modern code quality assessment.

Star History

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