# Code Quality Checklist

This document provides a quick reference for code quality checks that MUST be performed before completing any story.

## Pre-Completion Checklist

Before asking for user acceptance in Step 4 (Verification), ALL of the following must pass:

### Rust Backend

```bash
# 1. Run Clippy (linter)
cd src-tauri
cargo clippy --all-targets --all-features
# Expected: 0 errors, 0 warnings

# 2. Run cargo check (compilation)
cargo check
# Expected: successful compilation

# 3. Run tests
cargo test
# Expected: all tests pass
```

**Result Required:** ✅ 0 errors, 0 warnings, all tests pass

### TypeScript Frontend

```bash
# 1. Run TypeScript compiler check (type errors)
npx tsc --noEmit
# Expected: 0 errors

# 2. Run Biome check (linter + formatter)
npx @biomejs/biome check src/
# Expected: 0 errors, 0 warnings

# 3. Apply fixes if needed
npx @biomejs/biome check --write src/
npx @biomejs/biome check --write --unsafe src/  # for unsafe fixes

# 4. Build
npm run build
# Expected: successful build
```

**Result Required:** ✅ 0 errors, 0 warnings, successful build

## Common Biome Issues and Fixes

### 1. `noExplicitAny` - No `any` types

**Bad:**
```typescript
const handler = (data: any) => { ... }
```

**Good:**
```typescript
const handler = (data: { className?: string; children?: React.ReactNode; [key: string]: unknown }) => { ... }
```

### 2. `noArrayIndexKey` - Don't use array index as key

**Bad:**
```typescript
{items.map((item, idx) => <div key={idx}>...</div>)}
```

**Good:**
```typescript
{items.map((item, idx) => <div key={`item-${idx}-${item.id}`}>...</div>)}
```

### 3. `useButtonType` - Always specify button type

**Bad:**
```typescript
<button onClick={handler}>Click</button>
```

**Good:**
```typescript
<button type="button" onClick={handler}>Click</button>
```

### 4. `noAssignInExpressions` - No assignments in expressions

**Bad:**
```typescript
onMouseOver={(e) => (e.currentTarget.style.background = "#333")}
```

**Good:**
```typescript
onMouseOver={(e) => {
  e.currentTarget.style.background = "#333";
}}
```

### 5. `useKeyWithMouseEvents` - Add keyboard alternatives

**Bad:**
```typescript
<button onMouseOver={handler} onMouseOut={handler2}>...</button>
```

**Good:**
```typescript
<button 
  onMouseOver={handler} 
  onMouseOut={handler2}
  onFocus={handler}
  onBlur={handler2}
>...</button>
```

### 6. `useImportType` - Import types with `import type`

**Bad:**
```typescript
import { Message, Config } from "./types";
```

**Good:**
```typescript
import type { Message, Config } from "./types";
```

## Common Clippy Issues and Fixes

### 1. Unused variables

**Bad:**
```rust
} catch (e) {
```

**Good:**
```rust
} catch (_e) {  // prefix with underscore
```

### 2. Dead code warnings

**Option 1:** Remove the code if truly unused

**Option 2:** Mark as allowed if used conditionally
```rust
#[allow(dead_code)]
struct UnusedStruct {
    field: String,
}
```

### 3. Explicit return

**Bad:**
```rust
fn get_value() -> i32 {
    return 42;
}
```

**Good:**
```rust
fn get_value() -> i32 {
    42
}
```

## Quick Verification Script

Save this as `check.sh` and run before every story completion:

```bash
#!/bin/bash
set -e

echo "=== Checking Rust Backend ==="
cd src-tauri
cargo clippy --all-targets --all-features
cargo check
cargo test
cd ..

echo ""
echo "=== Checking TypeScript Frontend ==="
npx tsc --noEmit
npx @biomejs/biome check src/
npm run build

echo ""
echo "✅ ALL CHECKS PASSED!"
```

## Zero Tolerance Policy

- **No exceptions:** All errors and warnings MUST be fixed
- **No workarounds:** Don't disable rules unless absolutely necessary
- **No "will fix later":** Fix immediately before story completion
- **User must see clean output:** When running checks, show clean results to user

## When Rules Conflict with Requirements

If a linting rule conflicts with a legitimate requirement:

1. Document why the rule must be bypassed
2. Use the minimal scope for the exception (line/function, not file)
3. Add a comment explaining the exception
4. Get user approval

Example:
```typescript
// Biome requires proper types, but react-markdown types are incompatible
// Using unknown for compatibility
const code = ({ className, children }: { className?: string; children?: React.ReactNode; [key: string]: unknown }) => {
  ...
}
```

## Integration with SDSW

This checklist is part of **Step 4: Verification** in the Story-Driven Spec Workflow.

**You cannot proceed to story acceptance without passing all checks.**