improve-coverage

Improve test coverage for $ARGUMENTS.

Phase 1: Coverage Analysis

1. Generate coverage report
2. Identify untested functions, branches, error paths, edge cases

Phase 2: Test Priority

3. Prioritise by: critical business logic, complex functions, error handling, public APIs

Phase 3: Test Generation

4. Write tests covering edge cases, error conditions, and property-based tests where appropriate
5. Follow existing test patterns and conventions

Phase 4: Test Quality

5. Ensure tests are independent, clearly named, test one thing, and run quickly

Phase 5: Integration

6. Run full test suite, check coverage improvement, refactor for maintainability