Never optimize on a hunch. Take a measurement — a profile, a bundle analysis, a Core Web Vitals reading — locate the actual bottleneck, then fix that and re-measure to confirm the win. Findings without measurement are labeled potential impact, never presented as fact (the metric-honesty rule). Prevents speculative complexity that trades readability for imaginary performance.

Addy Osmani — Agent Skills:

Compound Engineering:

gstack:

  • gstack-benchmark — baseline Core Web Vitals / load, then compare before/after on every PR.

Tessl:

  • tessl-observability — measures where skills activate across real agent sessions, not where they are installed. The first capability here that measures agent behavior in production rather than in a test, and the distinction matters: a skill deployed everywhere and firing nowhere looks identical to a working one from any install-side view.

See Also