Mastra's classifier gate fails closed in 1.69

Mastra's core package reached version 1.69 with a change to how classifier guardrails behave when they break.

A broken classifier used to fail open, letting the request through anyway. In 1.69 it fails closed instead, so a classifier outage becomes an outage for everything it gates.

Classifiers are a first-class primitive in 1.69, and they also work as typed workflow steps. A new ClassifierProcessor sits in front of agent input, output, and streaming responses. If the classifier itself throws an error, the request aborts instead of passing through, per Mastra's release notes.

That reverses the default from before 1.69, when a broken classifier meant the check got skipped and the request went through regardless. Setting errorStrategy: 'warn' restores that old fail-open path. Teams that added classifier gates before 1.69 inherit fail-closed on upgrade unless they set that flag.

Fail-closed is the safer default for anything guarding against bad output. But it ties an agent's uptime to its classifier's uptime. If the classifier depends on an external model call, that dependency becomes a single point of failure. Every request the classifier gates depends on that call staying up.