Schema migration compatibility during major version upgrades

Biome utilizes a strict schema for its biome.json file to manage linting rules and formatting configurations. When upgrading between major versions, the configuration structure often undergoes breaking changes to accommodate new toolchain capabilities.

Currently, there is no native, automated rollback mechanism to programmatically revert the configuration to a previous schema state if a manual migration results in unexpected behavior. The CLI may fail to execute or ignore specific settings if the JSON structure does not align with the binary's expectations.

The uncertainty lies in how the engine handles deprecated keys versus entirely removed properties during the transition period between two major releases.

• How does Biome treat configuration keys that have been renamed in the latest version?
• Is there a recommended strategy for verifying schema compatibility before applying a major upgrade to a shared configuration?