name: codebase-rule-discovery
description: Analyzes TypeScript applications to discover patterns and propose coding conventions for shirokuma-docs lint rules. Use when "ルール発見", "rule discovery", "規約提案", "convention proposal", "パターン分析", or when investigating codebases to extract patterns or propose new conventions.
allowed-tools: Read, Grep, Glob, Bash, Write

Codebase Rule Discovery

Analyzes TypeScript applications in the monorepo for two purposes:
1. Pattern Discovery: Extract existing patterns across apps
2. Convention Proposal: Propose new conventions that enable mechanical checks

When to Use

• User requests "ルール発見", "rule discovery"
• User says "パターン分析", "pattern analysis"
• User mentions "規約提案", "convention proposal"
• User asks "もっとチェックできるようにしたい"
• User wants to "統一感を上げたい", "機械的チェックを増やしたい"

Two Modes

Mode 1: Pattern Discovery (既存パターン発見)

Goal: Find what patterns already exist across apps

現状のコードを分析 → 共通パターン発見 → ルール化提案

Mode 2: Convention Proposal (規約提案)

Goal: Propose conventions that ENABLE more mechanical checks

チェック可能性分析 → 規約提案 → 採用後にルール実装

Key Question: 「どう書けば機械的にチェックできるか？」

Target Applications

Workflow: Pattern Discovery

Step 1-7: (既存のワークフロー)

See workflows/analyze-codebase.md

Workflow: Convention Proposal

Step 1: Identify Check Opportunities

Analyze what COULD be checked if conventions existed:

Step 2: Analyze Current Structure

# File structure analysis
find apps/ -name "*.ts" -o -name "*.tsx" | head -100

# Directory patterns
ls -la apps/admin/lib/
ls -la apps/web/lib/

# Naming conventions
find apps/ -name "*.tsx" | xargs basename -a | sort | uniq -c | sort -rn

Step 3: Propose Conventions

For each opportunity, document:

1. Current State: How it's done now (with variations)
2. Proposed Convention: Specific rule
3. Migration Cost: How much code needs changing
4. Check Enabled: What lint rule becomes possible
5. Benefits: Why it's worth standardizing

Step 4: Generate Convention Proposal

Use templates/convention-proposal.md

Step 5: Save Report

Save to: logs/rule-discovery/YYYY-MM-DD-convention-{category}.md

Convention Categories

1. File Placement Conventions

2. Naming Conventions

3. Code Structure Conventions

4. Annotation Conventions

Existing Rules (Reference)

Check shirokuma-docs/src/lint/rules/ for current implementations.

Quick Reference

# Pattern discovery (Mode 1)
"discover patterns in blog-cms"

# Convention proposal (Mode 2)
"propose conventions for better checking"
"どうすればもっとチェックできる？"

# Specific areas
"propose file placement conventions"
"propose naming conventions"
"propose i18n key conventions"

Related Resources

• patterns/discovery-categories.md - What to look for
• templates/rule-proposal.md - Rule proposal format
• templates/convention-proposal.md - Convention proposal format
• workflows/analyze-codebase.md - Detailed workflow

Output

Convention proposals should answer:

1. What: 具体的な規約内容
2. Why: なぜこの規約が必要か
3. Check: どんなチェックが可能になるか
4. Migration: 既存コードの移行コスト
5. Priority: P0/P1/P2