Schema Snapshot Restore: Does it Re‑install Resolvers?

Goal

After a plugin that adds custom types via createSchemaCustomization is removed, a developer wishes to roll back the GraphQL schema to its prior state using Gatsby’s schema‑snapshot feature.

Uncertainty

The Gatsby documentation states that a snapshot captures the schema after all plugins run, but it does not specify whether a restore also re‑installs the associated resolvers or only the type definitions. Additionally, the ordering of createSchemaCustomization callbacks is not explicitly guaranteed, potentially leaving stale or duplicated resolver definitions after a rollback.

Specific Questions

1. When a snapshot is restored, are the original resolver functions for custom types re‑registered, or are only the type definitions restored?
2. Does the restore process clean up resolver definitions that were added by a plugin that has since been removed?
3. Is the order of createSchemaCustomization callbacks deterministic across all plugin types, and how does this affect rollback consistency?