# DECISIONS (append-only, shared)

## lex phase

### Token type
Used a simple class with `__slots__` for efficiency and `__eq__` for easy test assertions. No namedtuple to allow future extension (e.g. position tracking for later phases).

### Number regex
`r'\d+\.?\d*|\.\d+'` — handles `42`, `3.14`, `10.`, `.5`. The alternation order matters: longest match first via `re.match` at position `i`.

### EOF token
`Token('EOF', None)` — value is None since EOF carries no semantic content; downstream parser phases can type-check on `kind == 'EOF'`.