Implement according to the plan.
Refer only to files within the Report Directory shown in the Piece Context. Do not search or reference other report directories.

**Important**: Add unit tests alongside the implementation.
- Add unit tests for newly created classes and functions
- Update relevant tests when modifying existing code
- Test file placement: follow the project's conventions
- Running tests is mandatory. After completing implementation, always run tests and verify results

**Scope output contract (create at the start of implementation):**
```markdown
# Change Scope Declaration

## Task
{One-line task summary}

## Planned changes
| Type | File |
|------|------|
| Create | `src/example.ts` |
| Modify | `src/routes.ts` |

## Estimated size
Small / Medium / Large

## Impact area
- {Affected modules or features}
```

**Decisions output contract (at implementation completion, only if decisions were made):**
```markdown
# Decision Log

## 1. {Decision}
- **Context**: {Why the decision was needed}
- **Options considered**: {List of options}
- **Rationale**: {Reason for the choice}
```

**Required output (include headings)**
## Work results
- {Summary of actions taken}
## Changes made
- {Summary of changes}
## Test results
- {Command executed and results}