Code Hygiene Review

Review source code against 10 language-agnostic structural quality principles and produce a findings report with concrete refactoring suggestions.

Important: This skill produces a report. Do not modify any reviewed files.

Review Workflow

1. Select files — Use the user's specified files. If none specified, run scripts/scan-source-files.sh <project-directory> to discover source files. The <project-directory> argument is required — it must be the root of the user's project, NOT the skill's own directory.
2. Load rules — Read references/principles-quick-ref.md for the full checklist with detection signals and thresholds.
3. Review each file — Read each file and check against all 10 principles. Load detailed reference files on demand as violations are detected (see "When to Load Reference Files").
4. Generate findings — For each issue found, produce a finding using the Output Format below.
5. Classify severity — Use references/severity-rubric.md to assign high/medium/low.
6. Verify suggestions — For each suggested rewrite, confirm it resolves the flagged violation, does not introduce a new violation of any other principle, and preserves the original behavior. If a suggestion introduces a new violation, revise it before including it.
7. Assemble report — Write findings to code-hygiene-findings-YYYYMMDD.md in the project root (use today's date). Group findings by file, then by severity (high first). End with the summary block.

Output Format

Use this exact structure for each finding:

## [file path]

### Finding [N] — [Smell name] [ID] (severity: [high|medium|low])
- **Line [N]:** `[original code snippet]`
- **Principle:** [One-sentence explanation of the violated principle]
- **Refactoring:** [Named refactoring technique]
- **Suggested:**
  [concrete rewrite as a fenced code block]

Example:

## src/services/order_service.py

### Finding 1 — Hidden Dependency CH-02 (severity: high)
- **Line 8:** `self.db = PostgresConnection("prod:5432")`
- **Principle:** Dependencies created internally are invisible, untestable, and tightly coupled to a specific implementation.
- **Refactoring:** Inject via constructor parameter
- **Suggested:**
  ```python
  class OrderService:
      def __init__(self, db, mailer):
          self.db = db
          self.mailer = mailer
  ```

### Finding 2 — Nested Pyramid CH-03 (severity: medium)
- **Line 34:** 3 levels of nesting in `process_order()`
- **Principle:** Each nesting level forces the reader to maintain a mental stack. Guard clauses flatten the logic.
- **Refactoring:** Replace Nested Conditional with Guard Clauses
- **Suggested:**
  ```python
  def process_order(order):
      if not order:
          return None
      if not order.items:
          return None
      if not order.payment:
          raise ValueError("Missing payment")
      # happy path — no nesting
  ```

If a file has no findings, omit it from the report entirely.

End the report with:

## Summary
- **Files reviewed:** [N]
- **Total findings:** [N] ([N] high, [N] medium, [N] low)
- **Top issues:** [List the 2-3 most frequent violations]
- **Highest-leverage fix:** [The single change that would most improve the codebase]

When to Load Reference Files

Load references on demand to conserve context:

Scope Rules

• Review: application source code — functions, classes, modules, components
• Skip: test fixtures/factories, generated code, migration files, configuration files (JSON/YAML/TOML), vendor/third-party code, single-use scripts under 20 lines, type declaration files (.d.ts)
• Light touch: test files — apply naming (CH-09) and guard clauses (CH-03) but do not enforce DI (CH-02) or functional core (CH-10), since test setup is inherently side-effectful
• Do not modify reviewed files — produce recommendations only