feat(ecc): prune plugin 43→12 items, promote 7 rules to .claude/rules/ (#245)

ECC community plugin pruning: removed 530+ non-essential files
(.cursor/, .opencode/, docs/ja-JP, docs/zh-CN, docs/zh-TW,
language-specific skills/agents/rules). Retained 4 agents,
3 commands, 5 skills. Promoted 13 rule files (8 common + 5
typescript) to .claude/rules/ for CC native loading. Extracted
reusable patterns to EXTRACTED-PATTERNS.md.

.claude/rules/common/agents.md

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+# Agent Orchestration
+
+## Available Agents
+
+Located in `~/.claude/agents/`:
+
+| Agent | Purpose | When to Use |
+|-------|---------|-------------|
+| planner | Implementation planning | Complex features, refactoring |
+| architect | System design | Architectural decisions |
+| tdd-guide | Test-driven development | New features, bug fixes |
+| code-reviewer | Code review | After writing code |
+| security-reviewer | Security analysis | Before commits |
+| build-error-resolver | Fix build errors | When build fails |
+| e2e-runner | E2E testing | Critical user flows |
+| refactor-cleaner | Dead code cleanup | Code maintenance |
+| doc-updater | Documentation | Updating docs |
+
+## Immediate Agent Usage
+
+No user prompt needed:
+1. Complex feature requests - Use **planner** agent
+2. Code just written/modified - Use **code-reviewer** agent
+3. Bug fix or new feature - Use **tdd-guide** agent
+4. Architectural decision - Use **architect** agent
+
+## Parallel Task Execution
+
+ALWAYS use parallel Task execution for independent operations:
+
+```markdown
+# GOOD: Parallel execution
+Launch 3 agents in parallel:
+1. Agent 1: Security analysis of auth module
+2. Agent 2: Performance review of cache system
+3. Agent 3: Type checking of utilities
+
+# BAD: Sequential when unnecessary
+First agent 1, then agent 2, then agent 3
+```
+
+## Multi-Perspective Analysis
+
+For complex problems, use split role sub-agents:
+- Factual reviewer
+- Senior engineer
+- Security expert
+- Consistency reviewer
+- Redundancy checker

.claude/rules/common/coding-style.md

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+# Coding Style
+
+## Immutability (CRITICAL)
+
+ALWAYS create new objects, NEVER mutate existing ones:
+
+```
+// Pseudocode
+WRONG:  modify(original, field, value) → changes original in-place
+CORRECT: update(original, field, value) → returns new copy with change
+```
+
+Rationale: Immutable data prevents hidden side effects, makes debugging easier, and enables safe concurrency.
+
+## File Organization
+
+MANY SMALL FILES > FEW LARGE FILES:
+- High cohesion, low coupling
+- 200-400 lines typical, 800 max
+- Extract utilities from large modules
+- Organize by feature/domain, not by type
+
+## Error Handling
+
+ALWAYS handle errors comprehensively:
+- Handle errors explicitly at every level
+- Provide user-friendly error messages in UI-facing code
+- Log detailed error context on the server side
+- Never silently swallow errors
+
+## Input Validation
+
+ALWAYS validate at system boundaries:
+- Validate all user input before processing
+- Use schema-based validation where available
+- Fail fast with clear error messages
+- Never trust external data (API responses, user input, file content)
+
+## Code Quality Checklist
+
+Before marking work complete:
+- [ ] Code is readable and well-named
+- [ ] Functions are small (<50 lines)
+- [ ] Files are focused (<800 lines)
+- [ ] No deep nesting (>4 levels)
+- [ ] Proper error handling
+- [ ] No hardcoded values (use constants or config)
+- [ ] No mutation (immutable patterns used)

.claude/rules/common/git-workflow.md

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+# Git Workflow
+
+## Commit Message Format
+
+```
+<type>: <description>
+
+<optional body>
+```
+
+Types: feat, fix, refactor, docs, test, chore, perf, ci
+
+Note: Attribution disabled globally via ~/.claude/settings.json.
+
+## Pull Request Workflow
+
+When creating PRs:
+1. Analyze full commit history (not just latest commit)
+2. Use `git diff [base-branch]...HEAD` to see all changes
+3. Draft comprehensive PR summary
+4. Include test plan with TODOs
+5. Push with `-u` flag if new branch
+
+## Feature Implementation Workflow
+
+1. **Plan First**
+   - Use **planner** agent to create implementation plan
+   - Identify dependencies and risks
+   - Break down into phases
+
+2. **TDD Approach**
+   - Use **tdd-guide** agent
+   - Write tests first (RED)
+   - Implement to pass tests (GREEN)
+   - Refactor (IMPROVE)
+   - Verify 80%+ coverage
+
+3. **Code Review**
+   - Use **code-reviewer** agent immediately after writing code
+   - Address CRITICAL and HIGH issues
+   - Fix MEDIUM issues when possible
+
+4. **Commit & Push**
+   - Detailed commit messages
+   - Follow conventional commits format

.claude/rules/common/hooks.md

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+# Hooks System
+
+## Hook Types
+
+- **PreToolUse**: Before tool execution (validation, parameter modification)
+- **PostToolUse**: After tool execution (auto-format, checks)
+- **Stop**: When session ends (final verification)
+
+## Auto-Accept Permissions
+
+Use with caution:
+- Enable for trusted, well-defined plans
+- Disable for exploratory work
+- Never use dangerously-skip-permissions flag
+- Configure `allowedTools` in `~/.claude.json` instead
+
+## TodoWrite Best Practices
+
+Use TodoWrite tool to:
+- Track progress on multi-step tasks
+- Verify understanding of instructions
+- Enable real-time steering
+- Show granular implementation steps
+
+Todo list reveals:
+- Out of order steps
+- Missing items
+- Extra unnecessary items
+- Wrong granularity
+- Misinterpreted requirements

.claude/rules/common/patterns.md

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+# Common Patterns
+
+## Skeleton Projects
+
+When implementing new functionality:
+1. Search for battle-tested skeleton projects
+2. Use parallel agents to evaluate options:
+   - Security assessment
+   - Extensibility analysis
+   - Relevance scoring
+   - Implementation planning
+3. Clone best match as foundation
+4. Iterate within proven structure
+
+## Design Patterns
+
+### Repository Pattern
+
+Encapsulate data access behind a consistent interface:
+- Define standard operations: findAll, findById, create, update, delete
+- Concrete implementations handle storage details (database, API, file, etc.)
+- Business logic depends on the abstract interface, not the storage mechanism
+- Enables easy swapping of data sources and simplifies testing with mocks
+
+### API Response Format
+
+Use a consistent envelope for all API responses:
+- Include a success/status indicator
+- Include the data payload (nullable on error)
+- Include an error message field (nullable on success)
+- Include metadata for paginated responses (total, page, limit)

.claude/rules/common/performance.md

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+# Performance Optimization
+
+## Model Selection Strategy
+
+**Haiku 4.5** (90% of Sonnet capability, 3x cost savings):
+- Lightweight agents with frequent invocation
+- Pair programming and code generation
+- Worker agents in multi-agent systems
+
+**Sonnet 4.5** (Best coding model):
+- Main development work
+- Orchestrating multi-agent workflows
+- Complex coding tasks
+
+**Opus 4.5** (Deepest reasoning):
+- Complex architectural decisions
+- Maximum reasoning requirements
+- Research and analysis tasks
+
+## Context Window Management
+
+Avoid last 20% of context window for:
+- Large-scale refactoring
+- Feature implementation spanning multiple files
+- Debugging complex interactions
+
+Lower context sensitivity tasks:
+- Single-file edits
+- Independent utility creation
+- Documentation updates
+- Simple bug fixes
+
+## Extended Thinking + Plan Mode
+
+Extended thinking is enabled by default, reserving up to 31,999 tokens for internal reasoning.
+
+Control extended thinking via:
+- **Toggle**: Option+T (macOS) / Alt+T (Windows/Linux)
+- **Config**: Set `alwaysThinkingEnabled` in `~/.claude/settings.json`
+- **Budget cap**: `export MAX_THINKING_TOKENS=10000`
+- **Verbose mode**: Ctrl+O to see thinking output
+
+For complex tasks requiring deep reasoning:
+1. Ensure extended thinking is enabled (on by default)
+2. Enable **Plan Mode** for structured approach
+3. Use multiple critique rounds for thorough analysis
+4. Use split role sub-agents for diverse perspectives
+
+## Build Troubleshooting
+
+If build fails:
+1. Use **build-error-resolver** agent
+2. Analyze error messages
+3. Fix incrementally
+4. Verify after each fix

.claude/rules/common/security.md

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+# Security Guidelines
+
+## Mandatory Security Checks
+
+Before ANY commit:
+- [ ] No hardcoded secrets (API keys, passwords, tokens)
+- [ ] All user inputs validated
+- [ ] SQL injection prevention (parameterized queries)
+- [ ] XSS prevention (sanitized HTML)
+- [ ] CSRF protection enabled
+- [ ] Authentication/authorization verified
+- [ ] Rate limiting on all endpoints
+- [ ] Error messages don't leak sensitive data
+
+## Secret Management
+
+- NEVER hardcode secrets in source code
+- ALWAYS use environment variables or a secret manager
+- Validate that required secrets are present at startup
+- Rotate any secrets that may have been exposed
+
+## Security Response Protocol
+
+If security issue found:
+1. STOP immediately
+2. Use **security-reviewer** agent
+3. Fix CRITICAL issues before continuing
+4. Rotate any exposed secrets
+5. Review entire codebase for similar issues

.claude/rules/common/testing.md

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+# Testing Requirements
+
+## Minimum Test Coverage: 80%
+
+Test Types (ALL required):
+1. **Unit Tests** - Individual functions, utilities, components
+2. **Integration Tests** - API endpoints, database operations
+3. **E2E Tests** - Critical user flows (framework chosen per language)
+
+## Test-Driven Development
+
+MANDATORY workflow:
+1. Write test first (RED)
+2. Run test - it should FAIL
+3. Write minimal implementation (GREEN)
+4. Run test - it should PASS
+5. Refactor (IMPROVE)
+6. Verify coverage (80%+)
+
+## Troubleshooting Test Failures
+
+1. Use **tdd-guide** agent
+2. Check test isolation
+3. Verify mocks are correct
+4. Fix implementation, not tests (unless tests are wrong)
+
+## Agent Support
+
+- **tdd-guide** - Use PROACTIVELY for new features, enforces write-tests-first

.claude/rules/typescript/coding-style.md

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+---
+paths:
+  - "**/*.ts"
+  - "**/*.tsx"
+  - "**/*.js"
+  - "**/*.jsx"
+---
+# TypeScript/JavaScript Coding Style
+
+> This file extends [common/coding-style.md](../common/coding-style.md) with TypeScript/JavaScript specific content.
+
+## Immutability
+
+Use spread operator for immutable updates:
+
+```typescript
+// WRONG: Mutation
+function updateUser(user, name) {
+  user.name = name  // MUTATION!
+  return user
+}
+
+// CORRECT: Immutability
+function updateUser(user, name) {
+  return {
+    ...user,
+    name
+  }
+}
+```
+
+## Error Handling
+
+Use async/await with try-catch:
+
+```typescript
+try {
+  const result = await riskyOperation()
+  return result
+} catch (error) {
+  console.error('Operation failed:', error)
+  throw new Error('Detailed user-friendly message')
+}
+```
+
+## Input Validation
+
+Use Zod for schema-based validation:
+
+```typescript
+import { z } from 'zod'
+
+const schema = z.object({
+  email: z.string().email(),
+  age: z.number().int().min(0).max(150)
+})
+
+const validated = schema.parse(input)
+```
+
+## Console.log
+
+- No `console.log` statements in production code
+- Use proper logging libraries instead
+- See hooks for automatic detection

.claude/rules/typescript/hooks.md

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+---
+paths:
+  - "**/*.ts"
+  - "**/*.tsx"
+  - "**/*.js"
+  - "**/*.jsx"
+---
+# TypeScript/JavaScript Hooks
+
+> This file extends [common/hooks.md](../common/hooks.md) with TypeScript/JavaScript specific content.
+
+## PostToolUse Hooks
+
+Configure in `~/.claude/settings.json`:
+
+- **Prettier**: Auto-format JS/TS files after edit
+- **TypeScript check**: Run `tsc` after editing `.ts`/`.tsx` files
+- **console.log warning**: Warn about `console.log` in edited files
+
+## Stop Hooks
+
+- **console.log audit**: Check all modified files for `console.log` before session ends

.claude/rules/typescript/patterns.md

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+---
+paths:
+  - "**/*.ts"
+  - "**/*.tsx"
+  - "**/*.js"
+  - "**/*.jsx"
+---
+# TypeScript/JavaScript Patterns
+
+> This file extends [common/patterns.md](../common/patterns.md) with TypeScript/JavaScript specific content.
+
+## API Response Format
+
+```typescript
+interface ApiResponse<T> {
+  success: boolean
+  data?: T
+  error?: string
+  meta?: {
+    total: number
+    page: number
+    limit: number
+  }
+}
+```
+
+## Custom Hooks Pattern
+
+```typescript
+export function useDebounce<T>(value: T, delay: number): T {
+  const [debouncedValue, setDebouncedValue] = useState<T>(value)
+
+  useEffect(() => {
+    const handler = setTimeout(() => setDebouncedValue(value), delay)
+    return () => clearTimeout(handler)
+  }, [value, delay])
+
+  return debouncedValue
+}
+```
+
+## Repository Pattern
+
+```typescript
+interface Repository<T> {
+  findAll(filters?: Filters): Promise<T[]>
+  findById(id: string): Promise<T | null>
+  create(data: CreateDto): Promise<T>
+  update(id: string, data: UpdateDto): Promise<T>
+  delete(id: string): Promise<void>
+}
+```

.claude/rules/typescript/security.md

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+---
+paths:
+  - "**/*.ts"
+  - "**/*.tsx"
+  - "**/*.js"
+  - "**/*.jsx"
+---
+# TypeScript/JavaScript Security
+
+> This file extends [common/security.md](../common/security.md) with TypeScript/JavaScript specific content.
+
+## Secret Management
+
+```typescript
+// NEVER: Hardcoded secrets
+const apiKey = "sk-proj-xxxxx"
+
+// ALWAYS: Environment variables
+const apiKey = process.env.OPENAI_API_KEY
+
+if (!apiKey) {
+  throw new Error('OPENAI_API_KEY not configured')
+}
+```
+
+## Agent Support
+
+- Use **security-reviewer** skill for comprehensive security audits

.claude/rules/typescript/testing.md

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+---
+paths:
+  - "**/*.ts"
+  - "**/*.tsx"
+  - "**/*.js"
+  - "**/*.jsx"
+---
+# TypeScript/JavaScript Testing
+
+> This file extends [common/testing.md](../common/testing.md) with TypeScript/JavaScript specific content.
+
+## E2E Testing
+
+Use **Playwright** as the E2E testing framework for critical user flows.
+
+## Agent Support
+
+- **e2e-runner** - Playwright E2E testing specialist