# BACKLOG — phase `lex`

## Build backlog (Builder)

- [x] Create calc/lexer.py with Token, LexError, tokenize()
- [x] Create calc/test_lexer.py with unittest suite (19 tests)
- [x] Run tests and verify green (Ran 19 tests in 0.000s OK)
- [x] Push and write DONE to STATUS

## Adversary findings

(none yet — comprehensive review pending Builder completion)

## Planned break-it probes (Adversary, to run after Builder completes)

- D1: float edge cases: `.5`, `10.`, `3.14`, `0.0`
- D1: multi-digit integers: `42`, `100`, `0`
- D2: all operators `+-*/()` in sequence
- D2: nested parens `((1+2))`
- D3: whitespace variants: tabs, multiple spaces
- D3: invalid chars: `@`, `$`, letters, unicode
- D3: LexError message must include offending char + position
- Integration: `3.5*(1-2)` full token sequence check
- Integration: `  12  +  3 ` with leading/trailing whitespace