Decision GuideWhich testing level to use based on what changed.Which testing level to use based on what changed.In this sectionQuick Decision TableWhich testing level to use based on what changed.The Common AI Failure PatternHow AI agents fail by testing logic when the bug is visual.Required Testing BehaviorMandatory behaviors for AI agents when testing frontend code.Execution TiersWhere and when a test runs -- the second axis, orthogonal to testing levels.Heavy Test Decision RuleWhat to do when an E2E test is too heavy for PR CI — fix, demote, or delete, then classify why it is heavy and assign the right tier.NextQuick Decision TableRevision HistoryTakeshi TakatsudoCreated: 2026-04-04T07:11:52+09:00Updated: 2026-06-17T02:21:43+09:00