Configure and validate Confluent Schema Registry subject compatibility modes before deploying a schema change

Steps

1. Set the desired mode with a PUT to the subject's config endpoint (e.g. {"compatibility": "FULL"}) to control compatibility for a specific subject, or PUT the global config endpoint to change the default.
2. Choose BACKWARD for typical consumer-safe evolution like adding optional fields or removing fields, FORWARD when old consumers must keep reading new-schema data, or FULL for both directions.
3. Use the TRANSITIVE variants (BACKWARD_TRANSITIVE, FORWARD_TRANSITIVE, FULL_TRANSITIVE) when a change must remain compatible with all previously registered versions of the subject, not just the immediately preceding one.
4. Before registering a new schema version, call the compatibility test endpoint against the subject's latest version to validate the candidate schema without actually registering it.
5. Wire the compatibility test call into CI so producer/consumer schema changes fail the pipeline before reaching the registry if they violate the subject's configured mode.