Field Notes from a Merge Rule That Was Missing One Exception

Merge rules fail expensively when one exceptional path is missing because the workflow looks correct until the rare branch finally appears.

Most merge rules look correct until the one branch arrives that everyone assumed would never matter. That is usually the branch that teaches the expensive lesson.

What the team learned

• Exceptions need first-class treatment.
• Rare does not mean ignorable.
• Operators need evidence that explains why one branch was merged differently.

Use the security docs, audit schema, and architecture guide to make exceptions explicit.