Borrowed evidence

Two or more checks citing the same fire test log as proof, so one captured red run stands in for several guards and proves none of them. Every check needs its own evidence file naming that exact check. Shared proof is how a gate that looks fully evidenced ends up covering a single rule.

Principle 6 · Test that a check fires, not that it exists

Where does Borrowed evidence come from?

Principle 6 of the Kymira doctrine, Test that a check fires, not that it exists. Borrowed evidence is the name the doctrine gives to what that principle requires in practice.

What failure is Borrowed evidence named after?

Borrowed evidence. Two checks pointing at the same fire-test log, proving neither.

What does it look like on a real file?

Two checks cite the same fire test log, so one captured red run stands in for both and proves neither.

Not for

Not solved by more logging. One evidence file per check, naming that check, showing its own captured red run, is the requirement.

Nearest terms

Fire testA test that feeds a guard known bad input through the deployed production path and watches it...Fire-test theaterA test that re-implements the guard's comparison inline instead of calling the deployed guard Doctrine gateThe mechanical gate shipped with the packs and run over a finished deliverable folder before...

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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