- Extract TokenUsage as named type (eliminates inline struct repetition)
- Refactor main() into testable functions:
- readInputFromStdin: Read JSON from stdin
- parseStatusInput: Validate and parse JSON
- buildStatusLine: Construct left and right statusline parts
- calculatePadding: Compute padding for alignment
- formatOutput: Combine components into final output
- Add comprehensive tests for extracted functions
- Improve coverage from 45% to 71% (+26 percentage points)
- All new functions have 100% test coverage
- Clean linting with zero issues