Configure Worktrail's agent routing table (`~/.worktrail/routing.yaml`, or a repo-local `routing:` policy block) — which harness/model executes each role and tier, and how fallback between them works. Use when the operator wants to add or remove a harness/adapter (claude/codex/opencode), add a model to an existing harness (e.g. adding a DeepSeek model to opencode), pin or change who does code review, add a new tier or purpose mapping, change the default tier, or is confused about which harness actually served a spawn (e.g. "why did this use Codex when I only configured Claude"). Trigger phrases: "routing.yaml", "add a harness", "disable a harness", "add an adapter", "remove an adapter", "add a model", "add deepseek to opencode", "change the reviewer", "pin the reviewer", "routing tiers", "routing targets", "default_tier", "independent reviewer", "why did codex get called". This skill is about *editing the config file*; it does not cover `/go`'s own dispatch mechanics (see `worktrail-go`'s SKILL.md Phase 7 for how `tier_for()`/`select_cell()` resolve it at runtime).