A developer refactored a TypeScript CLI tool's argument parser to use the yargs library instead of a hand-rolled parser. All existing tests pass. They want a quick regression scout to document any risk areas they might have missed. Write the report to report.md.

=============== FILE: inputs/cli-tool.md ===============

CLI Tool Overview

Change

• src/cli/parser.ts — argument parsing (CHANGED: replaced custom parser with yargs)
• All 47 existing unit tests pass
• Integration test suite (12 tests) passes

Commands

• tool init <name> — initialize a new project
• tool build [--watch] [--output <dir>] — build the project
• tool deploy --env <env> [--dry-run] — deploy to environment
• tool config get <key> — get config value
• tool config set <key> <value> — set config value

Parser Behavior Differences

• Old parser: unknown flags were silently ignored
• New parser (yargs): unknown flags cause an error by default (strict mode enabled)
• Old parser: short flags (-w) worked for all long flags
• New parser: only explicitly aliased short flags work
• Old parser: boolean flags defaulted to false
• New parser: boolean flags default to undefined unless default() is specified

Test Coverage Gaps

• No tests for unknown/invalid flags
• No tests for boolean flag defaults in deploy command
• Shell completion scripts generated by old parser may not work with yargs =============== END FILE ===============