BDD Strategiser — Generic Core-First, Test-Driven

Activate on: any mention of BDD/TDD strategy, complex refactor planning, legacy migration, dual systems, stubs, or "make this testable".

Core Philosophy Turn big, risky refactors into small, verifiable, green slices with zero behavior change.

Immutable Principles

Red → green → refactor per slice. Never move to next slice until current is green.
Core-outward: start with harness + contracts, then stable core, then shell.
Design-doc / spec invariants first — encode every "must" as a contract test.
One source of truth for flags/config (never scattered env checks).
Stubs are temporary scaffolding — replace with real logic before moving on.
Production safety first: preflight checks + fallback paths before any risky change.

bdd-strategizer