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breaking change
Existing callers fail without edits. Renames, removed fields, stricter validation.
What is breaking change?
A breaking change makes previously valid use invalid: deleted endpoints, renamed props, a field that used to be optional and is now required, a new error for an old input.
Why does breaking change matter when vibe coding?
Models “clean up” an API and call it a refactor. Callers in other repos, mobile apps, and webhooks do not recompile with you. Name the break or you will ship it as a drive-by.
How do you do breaking change?
Grep callers, including mobile and external docs. If you must break, version the route or keep the old field one release. Write the migration for the caller, not only the server.
How do you ask a model for breaking change?
Do not break callers. Keep (old field / route) working. If a break is required, add it beside the old one and list every caller that must change.
What goes wrong with breaking change?
“Nobody uses that.” Somebody’s Friday script does. Search before you delete.