# ADR-030: Schema change detection via Value.Diff, not manual tracking

## Status

Accepted

## Context

Schema changes need to be detected when a stored graph type's Module diverges from the current Module definition. This could be tracked via a separate changelog or detected from the schemas themselves.

## Decision

The repository layer uses `Value.Diff(storedSchema, moduleEntry)` to detect when a stored schema has diverged from the current Module entry. This is schema-agnostic and works for any change — no separate changelog or version log needed. The `Edit[]` output from `Value.Diff` can optionally be classified as breaking or non-breaking.

## Consequences

- No manual changelog to maintain
- Works for any TypeBox schema change
- Classification of edits (breaking vs non-breaking) can be added later
- `moduleToDbSchema()` is used to update stored schemas after migration

## References

- [schema-evolution.md](../schema-evolution.md)