Fail closed

A failed check blocks the update instead of degrading it. The last known good version stays live and marked, a person is told, and no partial figure slips out under the old heading. Failing closed is an artifact, not an exit code: the build still writes a page carrying every verdict earned before the stop.

Principle 5 · Fail closed and stale

Where does Fail closed come from?

Principle 5 of the Kymira doctrine, Fail closed and stale. Fail closed is the name the doctrine gives to what that principle requires in practice.

What failure is Fail closed named after?

The stack trace deliverable. One unparseable date, a raw exception, zero artifacts, and 537 rows of provable verdicts discarded with it.

What does it look like on a real file?

Meridian's Monday cut misses its anchor, so Friday's pack stays live and marked while a person is told.

Not for

Not an exit code. A build that aborts with a stack trace and no artifacts has failed this rule, not satisfied it.

Nearest terms

Stale and correctThe state a certified system prefers when a check fails: last week's numbers, visibly labelled...BLOCKED reportThe page a build writes when it stops Staging swapAssembling every artifact of a build in a staging directory and moving it into the delivered...

Last updated 2026-09-02 · Dylan, founder · one of 40 terms in the Kymira glossary, each one named after something we watched go wrong in a real build or in our own audits.

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