# JOURNAL-lex

## 2026-06-15 — Implementation

Plan read. Building calc/lexer.py with Token dataclass, LexError, and tokenize().
Token kinds: NUMBER, PLUS, MINUS, STAR, SLASH, LPAREN, RPAREN, EOF.
Numbers: int or float value stored in token.value.
Whitespace skipped. Invalid chars raise LexError with char + position.