Decisions and attention items use monthly partitions with thirteen months kept

Context

Large history stores need predictable retention and inexpensive removal.

Decision

Partition decisions and occurrences by UTC month, retain thirteen completed months and maintain the current writable month plus two future months.

Alternatives Considered

Delete old records individually: Large row deletions create avoidable storage and maintenance costs.

Retain all history indefinitely: Unlimited retention grows the busiest stores without a recorded product need.

Consequences

Attention keys hold cross-partition open uniqueness. Sweep cleanup removes orphan supporting rows. Dropping an open occurrence removes it until a provider republishes the condition.