<!-- FIX-LINT:START -->

Lint Fix Expert Skill

When to Use This Skill

This skill automatically activates when:

• User asks to fix lint warnings
• User mentions "lint", "linter", or "static analysis"
• Working on code quality improvements
• User asks to fix ESLint, Clippy, or similar warnings

Lint Fix Process

Step 1: Detect Project Type and Linter

Foundry/Solidity

• Indicator: foundry.toml
• Format check: forge fmt --check
• Build warnings: forge build
• Solhint (if available): npx solhint 'contracts/**/*.sol'

Rust

• Indicator: Cargo.toml
• Linter: cargo clippy --all-targets --all-features -- -W clippy::all
• Format: cargo fmt --check

TypeScript/JavaScript

• Indicator: package.json
• ESLint: npm run lint or eslint .
• TypeScript: tsc --noEmit

Next.js

• Indicator: next.config.js or next.config.ts
• Lint: npm run lint (Next.js built-in ESLint)

Step 2: Get Warnings List

Run the linter to get all warnings:

# ESLint
npm run lint 2>&1

# Clippy
cargo clippy --all-targets 2>&1

# Foundry
forge build 2>&1
forge fmt --check 2>&1

Step 3: Prioritize Warnings

Fix warnings in this priority order:

1. Security Issues (Highest)

   • Unsafe operations
   • SQL injection risks
   • Command injection
   • Memory safety issues

2. Correctness Issues

   • Type errors
   • Logic bugs
   • Null/undefined risks

3. Performance Issues

   • Unnecessary allocations
   • Inefficient loops
   • Redundant operations

4. Code Quality

   • Unused variables
   • Deprecated APIs
   • Dead code

5. Style Issues (Lowest)

   • Formatting
   • Naming conventions
   • Import ordering

Step 4: Fix ONE Warning

Important: Fix only ONE warning per invocation for controlled changes.

Common Fixes by Linter

ESLint

Unused Variables

// Warning: 'x' is defined but never used
const x = getValue();  // Remove if truly unused

// Or prefix with underscore if intentionally unused
const _x = getValue();

Missing Await

// Warning: Promises must be awaited
async function process() {
    fetchData();  // Missing await
}

// Fix
async function process() {
    await fetchData();
}

Prefer Const

// Warning: 'x' is never reassigned
let x = 5;

// Fix
const x = 5;

Clippy (Rust)

Unnecessary Clone

// Warning: redundant clone
let s = str.clone();

// Fix: Remove clone if not needed
let s = str;

Unused Variables

// Warning: unused variable
let x = 5;

// Fix: Prefix with underscore
let _x = 5;

Needless Return

// Warning: unneeded `return` statement
fn foo() -> i32 {
    return 5;
}

// Fix
fn foo() -> i32 {
    5
}

Solidity/Foundry

Unused Imports

// Warning: Imported name "Foo" is not used
import {Foo, Bar} from "./contracts.sol";

// Fix: Remove unused
import {Bar} from "./contracts.sol";

State Mutability

// Warning: Function state mutability can be restricted to view
function getValue() public returns (uint256) {
    return value;
}

// Fix
function getValue() public view returns (uint256) {
    return value;
}

Visibility

// Warning: Function visibility not set
function foo() {
    // ...
}

// Fix
function foo() internal {
    // ...
}

Verification

After fixing:

# Re-run the linter
npm run lint  # ESLint
cargo clippy  # Rust
forge build   # Solidity

# Verify the specific warning is gone
# Run tests to ensure no regression
npm test
cargo test
forge test

Output Format

After fixing a warning:

## Lint Fix Summary

### Warning Fixed
**Type**: [Security/Correctness/Performance/Quality/Style]
**Linter**: [ESLint/Clippy/Solhint/Forge]
**Rule**: [rule-name]

### Location
**File**: `path/to/file.ts`
**Line**: 42

### Original Warning

[Exact warning message from linter]

### Fix Applied
```diff
- const x = getValue();
+ const _x = getValue();

Explanation

[Why this fix is appropriate]

Verification

• Linter no longer reports this warning
• Tests still pass
• No new warnings introduced

Commit

git add path/to/file.ts
git commit -m "fix(lint): [description of fix]"

## Integration with CI/CD

```yaml
name: Fix Lint

on:
  workflow_dispatch:

jobs:
  fix:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
      - run: npm ci
      - uses: anthropics/claude-code-action@v1
        with:
          claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
          prompt: /fix-lint

Best Practices

1. One at a time: Fix one warning per commit for clear history
2. Prioritize wisely: Security > Correctness > Performance > Style
3. Verify after fix: Always re-run linter and tests
4. Don't suppress blindly: Understand warnings before disabling
5. Update configs: If a rule is wrong for your project, update linter config

When to Suppress Instead of Fix

Sometimes suppression is appropriate:

// eslint-disable-next-line @typescript-eslint/no-explicit-any
const data: any = externalLib.getData();  // Third-party returns any

Only suppress when:

• External library limitations
• Intentional behavior that linter doesn't understand
• Legacy code that can't be changed safely
• Always add comment explaining why

<!-- FIX-LINT:END -->