ConsistencyConcurrency
Correctness under concurrent access and multi-step writes — see SYSTEM_DESIGN_ALIGNMENT.md sections 9.1, 9.2, 9.11.
Why we need this / what value this brings
Getting this wrong causes some of the hardest bugs to reproduce — race conditions and data corruption that only show up under real concurrent load.
When to use this
Whenever a write touches shared state that multiple requests could touch concurrently.
How to use or implement this
Default to your database's transaction guarantees; only reach for more complex patterns (sagas, custom locking) once ACID genuinely doesn't cover the case.
Subtopics
Empty folder — drop notes, links, and findings here as you research.