Spec

Lives at the root of your repo as SPEC.md and becomes the single source of truth for what you're building. It writes specs in a terse "caveman" format (defined in FORMAT.md) with sections for goals, constraints, interfaces, invariants, tasks, and bugs. The interesting bit is backprop: when you hit a bug, it traces the cause, adds a row to the bug table, and proposes a new invariant to catch it next time. Also distills specs from existing code if you inherit a project with no documentation. It's opinionated about monotonic numbering and pipe table layouts, which either saves you from bikeshedding or feels rigid depending on your taste. No auto-build, you invoke that yourself.