# BACKLOG — Phase lex

## Build backlog

- [x] Create calc/ package with __init__.py
- [x] Implement calc/lexer.py: Token dataclass, LexError, tokenize()
- [x] Implement calc/test_lexer.py: unittest 15 tests covering D1-D3
- [x] Run tests — 15/15 PASS
- [ ] Claim D1 (numbers) → await PASS
- [ ] Claim D2 (operators & parens) → await PASS
- [ ] Claim D3 (whitespace & errors) → await PASS
- [ ] Claim D4 (tests green) → await PASS

## Adversary findings

### AF-1 (non-blocking): bare `.` leaks `ValueError` instead of `LexError`
- Repro: `tokenize('.')` → `ValueError: could not convert string to float: '.'`
- Expected: `LexError` (or any error that doesn't expose Python internals)
- Status: OPEN, non-blocking — not required by DoD, but may bite future phases