Function-hooks plugin under mods/model-router: routes effort (and, behind a
flag, the model) of every main-loop request, sets built-in sub-agents' model
at spawn with full ids, answers Skill(effort-*) itself (single writer, no
pairing rule), exposes the route tool and /route, validates the optional
~/.claude/model-router.json. 11 plugin tests, validate + tsc clean.
Contract .claude/tasks/contracts/2026-10-08-model-router-w1a-1533.md.
bchanot
b721c94dcb