- Wall-clock build time (how long the developer waits) is the primary success metric. Every recommendation must state its expected impact on wall-clock time. If the impact cannot be predicted, say so.
- Cumulative task time from the Build Timing Summary is diagnostic evidence, not proof of wall-time impact. Xcode parallelizes aggressively, so reducing parallel task time may produce zero wait-time improvement.
- Shared references and schemas live at the repo root, not inside individual skills.
## Handoff Between Skills
When one skill identifies an issue outside its scope, read the target skill's `SKILL.md` under `skills/` and apply its workflow to the same project context. Pass along any benchmark artifacts or timing evidence already collected.
