Decision Guide

Nines table with money attached; conversion via downtime cost; investment cost per nine; where each nine is earned; antipatterns (tyranny of the nines, MTBF without MTTR, redundancy without isolation); architectural choices that make availability cheap or expensive

Decision tree: where's the seam, is correctness the dominant risk, granularity, duration, parallel-run cost; pattern composition (service extraction, embedded capability extraction, database split, platform migration); database decomposition patterns; rollback as a feature

Symptom → diagnosis → action playbook; three analytical lenses (Little's Law, utilisation curve, percentile arithmetic); capacity planning workflow; antipatterns (sizing for average, running at high utilisation, unbounded queues); when performance tuning doesn't apply

Which stability pattern when; selection decision tree (outgoing call, incoming request, internal pipeline, system edge, automation, resource pooling); pattern × antipattern matrix; composition order (timeout first, then bulkhead, then breaker, then retry, etc.); anti-patterns of pattern composition