compositionlisted

# Composition Wire two child modules together to satisfy a parent contract. You are not implementing new behaviour. You are routing data from the parent's inputs through the children's contracts to the parent's outputs, exactly as the parent contract specifies. ## Why this skill exists In a compartmentalised system, every node in the build tree either implements a leaf module (one contract, no children) or composes two child contracts under a parent contract. This skill handles the second case. It is structurally simpler than leaf implementation — the children already exist and are trusted; the parent contract already exists and is the target. The composition's job is only to wire one to the other faithfully. Because the work is constrained, this skill is the right place to use cheaper, smaller models. The rules below are deliberately tight to make that practical: most decisions are forced by the contracts involved, so there is little room for creative drift. When a genuine mismatch exists — child contracts that cannot be reconciled, a parent contract that cannot be satisfied by the children chosen for it — this skill does not try to solve the mismatch. It surfaces a precise re-raise back up the tree, where an agent with the authority and context can resolve it. ## What you have You have been given exactly six things: 1. **The parent contract** — the manifest the composition must satisfy. 2. **Child A's contract** — the manifest of the first child module. 3. **Child B