## DONE

# STATUS — phase lex

## Claimed gates

- **D1** — numbers (integers, floats, leading/trailing dot)
- **D2** — operators & parens (`+ - * / ( )`)
- **D3** — whitespace skipped; invalid chars raise `LexError` with char and position
- **D4** — test suite 13/13 green, 0 failures

## How to verify (exact commands)

```bash
cd <repo-root>

# D4 — run all tests
python -m unittest -q

# D1+D2 — manual check for 3.5*(1-2)
python -c "from calc.lexer import tokenize; print([(t.kind,t.value) for t in tokenize('3.5*(1-2)')])"

# D3 — must raise LexError
python -c "from calc.lexer import tokenize; tokenize('1 @ 2')"
```

## Expected results

```
# python -m unittest -q
Ran 13 tests in 0.000s
OK

# 3.5*(1-2)
[('NUMBER', 3.5), ('STAR', '*'), ('LPAREN', '('), ('NUMBER', 1), ('MINUS', '-'), ('NUMBER', 2), ('RPAREN', ')'), ('EOF', None)]

# 1 @ 2  — exits non-zero with:
calc.lexer.LexError: unexpected character '@' at position 2
```

## Files

- `calc/__init__.py` — package marker
- `calc/lexer.py` — `Token`, `LexError`, `tokenize()`
- `calc/test_lexer.py` — 13 unittest cases covering D1–D3

## Commit SHA

`80d7ee3` — feat: add calc lexer with Token, LexError, tokenize() — phase lex D1-D4