Module arithmetic 

Arithmetic expression evaluation for shell-style $(( )) expressions.

Supports:

• Integer arithmetic: +, -, *, /, %
• Comparison operators: >, <, >=, <=, ==, != (return 1 or 0)
• Parentheses for grouping: (expr)
• Variable references: $VAR or bare VAR
• Integer literals

Does NOT support:

• Floating point (pipe to jq for float math)
• Bitwise operations (shell-ism we’re skipping)
• Assignment within expressions (confusing)

Functions

eval_arithmetic

Evaluate an arithmetic expression string.