# revision: 21234e38cdb9a926cbc92bb97a2aee2e4a7d2916

## A. who calls the format-independent compatibility engine?
   (every hit below is either its own declaration or its own test)
src/messaging/messaging-schema-api/src/main/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidator.java:20:public final class SchemaCompatibilityValidator {
src/messaging/messaging-schema-api/src/main/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidator.java:29:  public SchemaCompatibilityValidator(SchemaRegistry registry) {
src/messaging/messaging-schema-api/src/main/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidator.java:42:  public List<SchemaVersion> versionsToCheck(String subject) {
src/messaging/messaging-schema-api/src/main/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidator.java:62:  public void requireProductionMode(String subject, String destination) {
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:13:class SchemaCompatibilityValidatorTest {
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:39:  private static SchemaCompatibilityValidator validator(SchemaCompatibility mode) {
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:40:    return new SchemaCompatibilityValidator(new FixedRegistry(List.of(V1, V2, V3), mode));
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:45:    assertThat(validator(SchemaCompatibility.BACKWARD).versionsToCheck("order.created"))
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:51:    assertThat(validator(SchemaCompatibility.BACKWARD_TRANSITIVE).versionsToCheck("order.created"))
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:59:    assertThat(validator(SchemaCompatibility.NONE_EXPERIMENTAL).versionsToCheck("order.created"))
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:65:    SchemaCompatibilityValidator validator =
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:66:        new SchemaCompatibilityValidator(
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:69:    assertThat(validator.versionsToCheck("order.created")).isEmpty();
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:77:                    .requireProductionMode("order.created", "orders.v1"))
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:87:                    .requireProductionMode("order.created", "orders.v1"))
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:93:    assertThat(SchemaCompatibilityValidator.checksBackward(SchemaCompatibility.FULL)).isTrue();
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:94:    assertThat(SchemaCompatibilityValidator.checksForward(SchemaCompatibility.FULL)).isTrue();
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:99:    assertThat(SchemaCompatibilityValidator.checksForward(SchemaCompatibility.BACKWARD)).isFalse();
src/messaging/messaging-schema-api/src/test/java/dev/caskeleton/messaging/schema/SchemaCompatibilityValidatorTest.java:100:    assertThat(SchemaCompatibilityValidator.checksBackward(SchemaCompatibility.FORWARD)).isFalse();

## B. the duplication that engine's javadoc exists to prevent
--- schema-api: allowlist form
  public static boolean checksBackward(SchemaCompatibility mode) {
    Objects.requireNonNull(mode, "mode must not be null");
    return mode == SchemaCompatibility.BACKWARD
        || mode == SchemaCompatibility.BACKWARD_TRANSITIVE
        || mode == SchemaCompatibility.FULL
        || mode == SchemaCompatibility.FULL_TRANSITIVE;
  }

  /**
   * Reports whether older readers must be able to read data written by the candidate.
   *
   * @param mode the compatibility mode
   * @return true when the forward direction is enforced
   */
  public static boolean checksForward(SchemaCompatibility mode) {
    Objects.requireNonNull(mode, "mode must not be null");
    return mode == SchemaCompatibility.FORWARD
        || mode == SchemaCompatibility.FORWARD_TRANSITIVE
        || mode == SchemaCompatibility.FULL
        || mode == SchemaCompatibility.FULL_TRANSITIVE;
  }

  /**
   * Reports whether a mode compares against the whole history.
   *
   * @param mode the compatibility mode
   * @return true for the transitive modes
   */
  public static boolean isTransitive(SchemaCompatibility mode) {
    Objects.requireNonNull(mode, "mode must not be null");
    return mode == SchemaCompatibility.BACKWARD_TRANSITIVE
        || mode == SchemaCompatibility.FORWARD_TRANSITIVE
        || mode == SchemaCompatibility.FULL_TRANSITIVE;
  }
--- schema-avro: private denylist form
  private static boolean isTransitive(SchemaCompatibility mode) {
    return mode == SchemaCompatibility.BACKWARD_TRANSITIVE
        || mode == SchemaCompatibility.FORWARD_TRANSITIVE
        || mode == SchemaCompatibility.FULL_TRANSITIVE;
  }

  private static boolean readsBackward(SchemaCompatibility mode) {
    return mode != SchemaCompatibility.FORWARD && mode != SchemaCompatibility.FORWARD_TRANSITIVE;
  }

  private static boolean readsForward(SchemaCompatibility mode) {
    return mode != SchemaCompatibility.BACKWARD && mode != SchemaCompatibility.BACKWARD_TRANSITIVE;
  }

## C. the platform's own SchemaRegistry port: any importer?
exit=1  (1 = no importer anywhere)
--- the SchemaRegistry name that IS imported elsewhere is a different type:
src/adapter/outbound/messaging/src/main/java/dev/caskeleton/adapter/outbound/messaging/envelope/LocalJsonSchemaRegistry.java:6:import com.networknt.schema.SchemaRegistry;
src/adapter/outbound/notification/src/main/java/dev/caskeleton/adapter/outbound/notification/platform/template/JsonSchemaVariableValidator.java:5:import com.networknt.schema.SchemaRegistry;

## D. codec consumers outside their owning leaf
JacksonMessageCodec        src/messaging/messaging-spring-boot-starter/src/main/java/dev/caskeleton/messaging/autoconfigure/MessagingCoreAutoConfiguration.java
AvroMessageCodec           NONE
AvroCompatibilityGate      NONE
ProtobufMessageCodec       NONE
ProtobufMessageContract    NONE
RawBytesMessageCodec       NONE
CloudEventMapper           NONE
DefaultCloudEventMapper    NONE
CloudEventExtensions       NONE

## E. registry membership of the codec leaves (does shipping match usage?)
messaging-schema-api         runtime_memberships=['app-bootstrap']
messaging-schema-json        runtime_memberships=['app-bootstrap']
messaging-schema-avro        runtime_memberships=[]
messaging-schema-protobuf    runtime_memberships=[]
messaging-cloudevents        runtime_memberships=['app-bootstrap']

## F. the raw-bytes default rule is enforced by content type, not by class
52:    if (ContentType.OCTET_STREAM.equals(defaultCodec.contentType())) {