Quick answer: Bug report velocity (reports/day) per feature surfaces stability. Tracking per-feature velocity over time identifies which features are stabilizing and which are degrading.
Per-feature velocity is the stability signal. Aggregate hides; per-feature reveals.
Per-feature tag
Bugs tagged with feature; velocity is bugs/day per tag.
Per-week trend
Plot per-feature; declining = stabilizing; growing = degrading.
Alert on growth
Velocity grows = investigate.
Per-release reset
Velocity resets per release; absolute count comparable.
“Stability is a per-feature property. Aggregate metrics miss.”
If your studio ships features, the per-feature velocity is the leading indicator of quality.