mutation

:EXPERIMENT: tool.mutation

Mutation testing on a tiny pure fn (my-max). Each mutation swaps one operator; each test drives the fn. A mutant is killed when the test suite notices the change; a mutant that survives every test is a gap.

Adapted from Markus Schirp's RubyConf 2026 talk Pattern Parrots and the Semantic Knot: Mutation Testing in the Agentic World (Thu 14:45 B2). Schirp's Ruby tool is mutant; this is a conceptual sibling scaled down to a single fn and a fixed suite. The point is to see the shape.

See experiments — this tool ships behind tool.mutation.