Promotion policies — when dev reaches stable

Module: agentdescent.defaults · Contract: PromotionPolicy.promote(ctx) -> Sequence[Promotion]

The dual-branch rule: dev absorbs candidates, stable is what production reads, and promotion is the EMA-style confirmation between them.

Implemented

Policy	Rule	Reach for it when
DefaultPromotion(promote_after_k=None) — None takes the run's AggregatorConfig.promote_after_k	promote after K regression-free rounds on dev; the counter resets on any regression	the default; read its docstring before replacing it — the reset semantics are the part everyone gets wrong

A clean run also promotes on finalize(): target_reward can fire on the very commit that reaches it, and the artifact the run was for must reach the branch production reads.

What the default knows that a replacement must be told

Promotion counts rounds survived, not commits. Counting commits inverts the incentive: an artifact that converges stops committing and so can never be promoted, while one that thrashes promotes every K commits.