# issue-08-gitignore-enhancement: Update .gitignore with Artifact Patterns

## Description
Append comprehensive artifact patterns to `.gitignore` to prevent future file pollution. This includes backup files (`*.log`, `*.bak`, `*.tmp`, `*.backup`), build artifacts (`dhat-heap.json`, `*.rlib`), Claude outputs (`.claude_output_*.json`), documentation builds (`/docs/book/`), and benchmark outputs (`/benches/*.json`, `/benches/*.svg`). Addresses PRD AC11 by ensuring all identified artifact patterns are covered.

## Architecture Reference
Read `/Users/santoshkumarradha/Documents/agentfield/code/int-agentfield-examples/af-swe/example-pyrust/.artifacts/plan/architecture.md` Section "Component 10: .gitignore Enhancement" (lines 646-711) for:
- Complete list of patterns to append
- Section headers for organization
- Pattern verification strategy using `git check-ignore -v`
- Expected grep match counts for validation

## Interface Contracts
- **Input**: Current `.gitignore` with 3 lines (`.worktrees/`, `/target`, `Cargo.lock`)
- **Output**: Enhanced `.gitignore` with 14+ patterns organized by category
- **Operations**: Append-only (no modifications to existing patterns)

## Isolation Context
- Available: Clean filesystem (issue-07 file cleanup completed)
- NOT available: Code from same-level parallel issues
- Source of truth: Architecture document Component 10 for exact patterns

## Files
- **Modify**: `.gitignore` (append patterns with section headers)

## Dependencies
None (can run in parallel with other Phase 1 components)

## Provides
- Comprehensive `.gitignore` preventing future artifact pollution
- Pattern coverage for backup files, build artifacts, Claude outputs, benchmark results

## Acceptance Criteria
- [ ] `grep -E '(\.log|\.bak|\.tmp|\.backup)' .gitignore | wc -l` outputs at least 4
- [ ] `grep 'dhat-heap\.json' .gitignore | wc -l` outputs 1
- [ ] `grep '\.claude_output_\*\.json' .gitignore | wc -l` outputs 1
- [ ] `grep '\.rlib' .gitignore | wc -l` outputs 1
- [ ] Total: `grep -E '(\.log|\.bak|\.tmp|\.backup|dhat-heap\.json|\.rlib|\.claude_output.*\.json)' .gitignore | wc -l` outputs at least 7

## Testing Strategy

### Test Files
None (verification through grep pattern matching)

### Test Categories
- **Pattern matching**: Use `git check-ignore -v bench_output.log` to verify pattern matches
- **Duplicate detection**: Ensure Cargo.lock already present, no duplicate additions
- **Completeness**: Count all backup/temp patterns present

### Run Command
```bash
git check-ignore -v bench_output.log dhat-heap.json .claude_output_test.json
```

## Verification Commands
- Build: N/A (no compilation needed)
- Test: `grep -E '(\.log|\.bak|\.tmp|\.backup|dhat-heap\.json|\.rlib|\.claude_output.*\.json)' .gitignore | wc -l` (expected: ≥7)
- Check: `git check-ignore -v bench_output.log` (should show match from .gitignore)
