updating-artifact-schema

name	updating-artifact-schema
description	Use whenever changing the schema of a persistent artifact, including config files, transcripts, caches, checkpoints, credential metadata, or other data read across software versions.

Updating Artifact Schemas

1. Inspect every reader, writer, strict parser, test, and historical shape before editing.
2. For hand-written artifacts, prefer ordered, shape-driven, idempotent migrations without a required version key. Use explicit versions only when shapes cannot be distinguished safely.
3. Parse into a generic representation, run all migrations in order, then strictly deserialize the latest shape.
4. Add one migration per schema change; never rewrite an older migration. Preserve the new value when old and new fields coexist.
5. Make every writer emit only the latest shape. Do not rewrite user-owned files on read unless explicitly required.
6. Test legacy and current shapes, mixed-key conflicts, malformed values, and writer output.
7. Follow repository release rules, then run the smallest relevant format, test, and lint checks.