# ADR-031: moduleToDbSchema() for schema updates, not Value.Patch

## Status

Accepted

## Context

When a graph type Module changes, the stored schema in `node_types.schema` must be updated. This could be done by patching the stored schema with `Value.Patch` or by re-running `moduleToDbSchema()` on the full Module.

## Decision

Re-run `moduleToDbSchema()` on the updated Module. Patch-based schema update (`Value.Patch`) is unreliable for `Type.Ref`/`$defs` changes — the diff is structural, not semantic, and may not capture `$defs` reorganization correctly. `moduleToDbSchema()` is more reliable because it always produces a fresh, complete projection.

Patch-based schema update is an optimization for later.

## Consequences

- Schema updates always go through `moduleToDbSchema()`
- The full Module must be available at migration time
- No risk of partial/partially-correct patches from `Value.Diff`
- Patch-based update can be added as an optimization if needed

## References

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