# JOURNAL — Phase `parse`

## Session 1 — initial implementation

**Plan:** Recursive-descent parser. Grammar:
```
expr    → term (('+' | '-') term)*
term    → unary (('*' | '/') unary)*
unary   → '-' unary | primary
primary → NUMBER | '(' expr ')'
```

This naturally encodes `*/` tighter than `+-` (D1) and left-associativity via the while loops (D2). Unary minus (D4) handled in `_unary` before `_primary`.

**Test run:**
```
$ python -m unittest -q
----------------------------------------------------------------------
Ran 34 tests in 0.001s
OK
```

**Key assertions verified manually:**
```
1+2*3  → BinOp('+', Num(1), BinOp('*', Num(2), Num(3)))   ✓ D1
8-3-2  → BinOp('-', BinOp('-', Num(8), Num(3)), Num(2))    ✓ D2
8/4/2  → BinOp('/', BinOp('/', Num(8), Num(4)), Num(2))    ✓ D2
(1+2)*3 → BinOp('*', BinOp('+', Num(1), Num(2)), Num(3))  ✓ D3
-5     → Unary('-', Num(5))                                  ✓ D4
-(1+2) → Unary('-', BinOp('+', Num(1), Num(2)))            ✓ D4
3 * -2 → BinOp('*', Num(3), Unary('-', Num(2)))            ✓ D4
```

Error cases ('1 +', '(1', '1 2', ')(', '') all raise ParseError ✓ D5