# JOURNAL — phase eval

## 2026-06-15 — Initial implementation

### What I built
- `calc/evaluator.py`: `evaluate(node)` walks Num/BinOp/Unary AST nodes recursively. SLASH branch guards `right == 0` and raises `EvalError("division by zero")`.
- `calc.py`: CLI entry point. `fmt(value)` converts whole-valued floats to int string. Catches `LexError|ParseError|EvalError`, prints to stderr, exits 1.
- `calc/test_evaluator.py`: 11 tests across 3 classes covering D1–D3.

### Local verification

```
$ python -m unittest -q
----------------------------------------------------------------------
Ran 50 tests in 0.003s

OK

$ python calc.py "2+3*4"
14
$ python calc.py "(2+3)*4"
20
$ python calc.py "7/2"
3.5
$ python calc.py "4/2"
2
$ python calc.py "1/0"
error: division by zero   (stderr, exit 1)
$ python calc.py "1 +"
error: unexpected token 'EOF'   (stderr, exit 1)
```

All D1–D5 verified locally.