The 8-ilities

Make the system understandable, operable, and changeable.

• What component do people avoid touching?
• How long does onboarding take?
• What breaks most often during releases?

Resist unauthorized access and misuse.

• What is our biggest unmitigated threat today?
• Can we prove authorization correctness?
• How fast can we revoke access everywhere?

Help intended users achieve outcomes with minimal friction.

• Who are the primary personas and what are their top outcomes?
• Where do support tickets cluster?
• What requires explanation that shouldn’t?

Handle growth and demand variability efficiently.

• What saturates first under load?
• Do retries amplify incidents?
• Can components scale independently?

Evolve without disruptive redesign.

• Where does change feel expensive?
• What requires broad coordination?
• Are contracts versioned and explicit?

Deliver functionality when users need it.

• What dependency outage hurts most?
• Do we degrade gracefully?
• What is user-perceived uptime vs internal uptime?

Preserve data/state across failures.

• When did we last perform a full restore?
• What is our acceptable data loss window?
• Can corruption propagate silently?

Move across environments and platforms.

• Could we recreate prod elsewhere in 30 days?
• What is environment-specific today?
• How mobile is our data?