Wait-event triage map

A decision tree from one pg_stat_activity snapshot to the next safe action.

The map is deliberately conservative: preserve evidence first, separate expected idleness from stalled work, and only then choose a class-specific drill-down.

Minimum evidence bundle

Two or more snapshots with timestamps.
pid, backend_type, state, query age, transaction age, event type and name.
pg_blocking_pids(pid) for every waiting backend.
The exact PostgreSQL major/minor version.
A workload marker: deploy, batch, checkpoint, vacuum, backup, DDL, or failover.

Warning

Do not terminate a backend merely because its wait is frequent. Activity, many Client, and timer waits can dominate a healthy cluster by design.