Skill Optimizer
Self-evolving skill optimization. Treats SKILL.md as the trainable parameters of a frozen agent. Validation-gated, budget-capped, atomic-versioned.
Based on SkillOpt (arXiv 2605.23904, Microsoft Research, May 2026).
When to invoke this skill
The user wants to:
- Improve an existing skill's execution quality against a benchmark
- Bootstrap a benchmark file for a new skill
- Re-tune a skill after switching target models
Iron Law
- Validation gating is MANDATORY. Every candidate must clear median-of-3
- epsilon=0.05 margin against the sel-set before SKILL.md gets rewritten.
- Frontmatter mutation is FORBIDDEN. The optimizer only edits the body.
Routing surface (
triggers:,brain_first:) stays invariant. - Bundled skills require explicit opt-in AND an independent held-out set.
Skills shipping with gbrain cannot be auto-mutated. To rewrite one in place
the user passes BOTH
--allow-mutate-bundledAND--held-out <path>with at least 5 benchmark-disjoint tasks; without the held-out set the run hard-refuses (exit 2). Drop--allow-mutate-bundled(or pass--no-mutate, the default for the dream-cycle phase) to write proposed.md…
