Claude Code Usage

---
name: claude-code-usage
description: "[AUTO-INVOKE] MUST be invoked at the START of each new coding session. Covers context management, task strategies, and Foundry-specific workflows. Trigger: beginning of any new conversation or coding session in a Solidity/Foundry project."
---

# Claude Code Best Practices

## Language Rule

- **Always respond in the same language the user is using.** If the user asks in Chinese, respond in Chinese. If in English, respond in English.

## Context Management Rules

| Rule | Why |
|------|-----|
| One window = one task | Mixing tasks pollutes context and degrades output quality |
| Use `/clear` over `/compact` | Clean start is more reliable than compressed context |
| `/clear` after complex tasks | Prevents old context from interfering with new work |
| Copy key info to new windows | Don't rely on context persistence — paste critical details |

## Task Execution Strategy

| Task Type | Recommended Approach |
|-----------|---------------------|
| Small bug fix (few lines) | Describe directly, let Claude modify in-place |
| Large feature / refactor | `/plan` → review approach → `/clear` → paste plan → execute step by step |
| Multi-file changes | Must use `/plan` workflow — never modify multiple files without a plan |
| Code analysis / learning | Ask Claude to analyze directly — no plan needed |
| Debugging | Provide error message + file path + relevant code — ask for root cause |

## Prompt Techniques

### Do This

- Give specific paths: *"Modify the `_transfer` function in `src/MyToken.sol`"*
- Give examples: *"Input: 100 tokens, Expected: 95 tokens after 5% fee"*
- Set boundaries: *"Only modify this function, don't touch other code"*
- Reference tests: *"The fix should make `test_transfer_feeDeduction` pass"*

### Avoid This

- Vague references: *"Modify that transfer function"* — which one? Where?
- Open-ended requests without constraints: *"Make it better"*
- Multiple unrelated tasks in one message

## Meta-Prompting — When Things Go Wrong

When Claude's response misses the mark, don't just rephrase and retry. Use **Meta-Prompting** (reverse prompting) to let Claude diagnose the gap, then re-ask with complete context.

### Four Prompt Types

| Type | When to Use | Template |
|------|-------------|----------|
| **Diagnose** | Answer was wrong or incomplete | *"我刚才的提问中缺少了哪些关键信息，导致你没能一次性给出正确答案？请逐条列出。"* |
| **Rewrite** | You don't know how to improve the question | *"请帮我重写刚才的问题，补全你认为缺失的上下文，使你能一次性给出正确答案。"* |
| **Template** | Prevent same mistake next time | *"对于这类问题，我应该提供哪些信息你才能一次性解决？请给我一个提问模板。"* |
| **Pre-check** | Before Claude starts working | *"在你开始写代码之前，列出你还需要我提供的所有信息。"* |

### Recommended Flow

```
Step 1: Ask your question
        ↓ (answer is wrong or incomplete)
Step 2: Use [Diagnose] — "我的问题中缺少了什么？"
        ↓ (Claude lists missing info)
Step 3: Use [Rewrite] — "帮我重写这个问题"
        ↓ (Claude outputs a complete, self-contained prompt)
Step 4: Copy the rewritten prompt, `/clear`, paste and send
        ↓ (clean context + complete prompt = correct answer)
```

### Practical Example

```
# Round 1 — incomplete question
User: "帮我写一个 staking 合约"
Claude: (generates a basic staking contract, but missing reward logic)

# Round 2 — diagnose
User: "我刚才的提问中缺少了哪些信息？"
Claude: "你没有说明：
  1. 质押代币和奖励代币是否相同
  2. 奖励分发机制（按时间/按区块/固定APR）
  3. 是否需要锁仓期
  4. 是否需要紧急提取功能
  5. 管理员权限范围"

# Round 3 — rewrite
User: "帮我重写这个问题"
Claude: "请帮我写一个 Staking 合约，要求如下：
  - 质押代币：ERC20 TOKEN_A，奖励代币：ERC20 TOKEN_B
  - 奖励机制：按质押时长线性释放，年化 12%
  - 锁仓期：7 天最短锁仓
  - 紧急提取：支持，但扣除 10% 罚金
  - 管理员：可更新奖励率，不可触碰用户质押资金
  - 安全：使用 ReentrancyGuard + SafeERC20
  请基于 OpenZeppelin 5.x，Solidity ^0.8.20，Foundry 项目结构。"

# Round 4 — /clear, paste rewritten prompt, get correct result
```

### Key Principle

> **Don't guess what you missed — let Claude tell you.** One round of meta-prompting saves multiple rounds of trial and error.

## Git Operation Rules

- Always run `git diff` before committing to review changes
- Only commit — do not push unless explicitly requested
- Never push directly to main/master branch
- Stage specific files — never use `git add .` in Solidity projects (risk of committing `.env`)

## Foundry-Specific Workflow

| Action | Command |
|--------|---------|
| Before committing | `forge fmt && forge test` |
| After modifying contracts | `forge build` to check compilation |
| Before PR | `forge test --gas-report` to check gas impact |
| Debugging failed test | `forge test --match-test <name> -vvvv` for full trace |

## Quick Command Reference

| Command | Purpose |
|---------|---------|
| `/clear` | Clear context, start fresh |
| `/plan` | Enter planning mode — analyze before modifying |
| `/help` | View all available commands |
| `/compact` | Compress context (prefer `/clear` instead) |

## Project-level Configuration

Create `.claude/instructions.md` in the project root with project-specific rules. Claude automatically reads it at the start of every conversation — no manual loading needed.