fix: unified exceptions and reactive pattern hardening

pom.xml

@@ -76,6 +76,13 @@
             <artifactId>jackson-datatype-jsr310</artifactId>
         </dependency>
 
+        <!-- Firefly Kernel (foundational: exceptions, shared abstractions) -->
+        <dependency>
+            <groupId>org.fireflyframework</groupId>
+            <artifactId>fireflyframework-kernel</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+
         <!-- Observability (metrics, tracing, health, structured logging) -->
         <dependency>
             <groupId>org.fireflyframework</groupId>

src/main/java/org/fireflyframework/transactional/saga/composition/CompositionValidationException.java

@@ -16,6 +16,8 @@
 
 package org.fireflyframework.transactional.saga.composition;
 
+import org.fireflyframework.kernel.exception.FireflyException;
+
 import java.util.List;
 import java.util.stream.Collectors;
 
@@ -26,7 +28,7 @@
  * during composition building, including helpful suggestions for
  * resolving the problems.
  */
-public class CompositionValidationException extends RuntimeException {
+public class CompositionValidationException extends FireflyException {
 
     private final String compositionName;
     private final List<ValidationIssue> validationIssues;

src/main/java/org/fireflyframework/transactional/saga/engine/ReactiveStreamOptimizations.java

@@ -17,6 +17,7 @@
 
 package org.fireflyframework.transactional.saga.engine;
 
+import org.fireflyframework.kernel.exception.FireflyException;
 import org.fireflyframework.transactional.saga.core.SagaContext;
 import org.fireflyframework.transactional.saga.registry.SagaDefinition;
 import org.fireflyframework.transactional.saga.registry.StepDefinition;
@@ -319,7 +320,7 @@ public interface LayerExecutor {
         Mono<String> executeStep(String stepId);
     }
 
-    public static class CircuitBreakerException extends RuntimeException {
+    public static class CircuitBreakerException extends FireflyException {
         public CircuitBreakerException(String message) {
             super(message);
         }

src/main/java/org/fireflyframework/transactional/saga/engine/SagaCompensator.java

@@ -17,6 +17,7 @@
 
 package org.fireflyframework.transactional.saga.engine;
 
+import org.fireflyframework.kernel.exception.FireflyException;
 import org.fireflyframework.transactional.saga.core.SagaContext;
 import org.fireflyframework.transactional.saga.registry.SagaDefinition;
 import org.fireflyframework.transactional.saga.registry.StepDefinition;
@@ -304,7 +305,7 @@ private Object resolveCompensationArg(Method comp, Object input, Object result)
     /**
      * Exception thrown when compensation fails and the error handler decides to fail the saga.
      */
-    public static class CompensationFailedException extends RuntimeException {
+    public static class CompensationFailedException extends FireflyException {
         public CompensationFailedException(String message, Throwable cause) {
             super(message, cause);
         }

src/main/java/org/fireflyframework/transactional/saga/persistence/serialization/SagaStateSerializer.java

@@ -16,6 +16,7 @@
 
 package org.fireflyframework.transactional.saga.persistence.serialization;
 
+import org.fireflyframework.kernel.exception.FireflyException;
 import org.fireflyframework.transactional.saga.persistence.SagaExecutionState;
 
 /**
@@ -80,7 +81,7 @@ public interface SagaStateSerializer {
     /**
      * Exception thrown when serialization or deserialization fails.
      */
-    class SerializationException extends Exception {
+    class SerializationException extends FireflyException {
         public SerializationException(String message) {
             super(message);
         }

src/main/java/org/fireflyframework/transactional/saga/validation/SagaValidationService.java

@@ -16,6 +16,7 @@
 
 package org.fireflyframework.transactional.saga.validation;
 
+import org.fireflyframework.kernel.exception.FireflyException;
 import org.fireflyframework.transactional.saga.registry.SagaDefinition;
 import org.fireflyframework.transactional.saga.registry.SagaRegistry;
 import org.fireflyframework.transactional.saga.registry.StepDefinition;
@@ -284,11 +285,11 @@ public void validateSagaInputsOrThrow(SagaDefinition saga, Object inputs) throws
     /**
      * Exception thrown when saga validation fails.
      */
-    public static class SagaValidationException extends Exception {
+    public static class SagaValidationException extends FireflyException {
         public SagaValidationException(String message) {
             super(message);
         }
-        
+
         public SagaValidationException(String message, Throwable cause) {
             super(message, cause);
         }

src/main/java/org/fireflyframework/transactional/saga/validation/SagaValidator.java

@@ -16,6 +16,7 @@
 
 package org.fireflyframework.transactional.saga.validation;
 
+import org.fireflyframework.kernel.exception.FireflyException;
 import org.fireflyframework.transactional.saga.registry.SagaDefinition;
 import org.fireflyframework.transactional.saga.registry.StepDefinition;
 
@@ -266,7 +267,7 @@ private static void validateInputRequirements(SagaDefinition saga, Object inputs
     /**
      * Exception thrown when circular dependencies are detected.
      */
-    public static class CircularDependencyException extends Exception {
+    public static class CircularDependencyException extends FireflyException {
         public CircularDependencyException(String message) {
             super(message);
         }

src/main/java/org/fireflyframework/transactional/shared/annotations/EnableTransactionalEngine.java

@@ -17,8 +17,6 @@
 
 package org.fireflyframework.transactional.shared.annotations;
 
-import org.fireflyframework.transactional.saga.config.SagaPersistenceAutoConfiguration;
-import org.fireflyframework.transactional.saga.config.SagaRedisAutoConfiguration;
 import org.fireflyframework.transactional.shared.config.TransactionalEngineConfiguration;
 import org.springframework.context.annotation.Import;
 
@@ -27,17 +25,26 @@
 /**
  * Enables the Transactional Engine (Saga orchestrator) components in a Spring application.
  * <p>
- * Imports {@link org.fireflyframework.transactional.config.TransactionalEngineConfiguration} that wires:
+ * This annotation imports {@link TransactionalEngineConfiguration} directly so it works
+ * in both Spring Boot (auto-configuration) and plain Spring contexts
+ * (e.g. {@code AnnotationConfigApplicationContext}).
+ * <p>
+ * Additional conditional configurations (persistence, Redis, composition) are registered via
+ * {@code META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports}
+ * and activated automatically in Spring Boot applications.
+ * <p>
+ * Components wired by this annotation:
  * - {@code SagaRegistry}: scans for @Saga beans and indexes steps
  * - {@code SagaEngine}: the in-memory orchestrator
- * - {@code SagaEvents}: default implementation {@code SagaLoggerEvents} (override by declaring your own bean)
+ * - {@code TccEngine}: the TCC coordinator
+ * - {@code SagaEvents}: default implementation (override by declaring your own bean)
  * - {@code StepLoggingAspect}: AOP aspect for additional logging
  * - {@code WebClient.Builder}: convenience bean for HTTP clients
  */
 @Target(ElementType.TYPE)
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
 @Inherited
-@Import({TransactionalEngineConfiguration.class, SagaPersistenceAutoConfiguration.class, SagaRedisAutoConfiguration.class})
+@Import(TransactionalEngineConfiguration.class)
 public @interface EnableTransactionalEngine {
 }

src/main/java/org/fireflyframework/transactional/shared/config/TransactionalEngineConfiguration.java

@@ -156,6 +156,12 @@ public TccEventPublisher tccEventPublisher() {
         return new NoOpTccEventPublisher();
     }
 
+    @Bean
+    @ConditionalOnMissingBean
+    public SagaPersistenceProvider sagaPersistenceProvider() {
+        return new org.fireflyframework.transactional.saga.persistence.impl.InMemorySagaPersistenceProvider();
+    }
+
     @Bean
     @ConditionalOnMissingBean
     public TccPersistenceProvider tccPersistenceProvider() {

src/main/java/org/fireflyframework/transactional/shared/engine/backpressure/CircuitBreakerBackpressureStrategy.java

@@ -16,6 +16,7 @@
 
 package org.fireflyframework.transactional.shared.engine.backpressure;
 
+import org.fireflyframework.kernel.exception.FireflyException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import reactor.core.publisher.Flux;
@@ -254,7 +255,7 @@ public record CircuitBreakerMetrics(
     /**
      * Exception thrown when circuit breaker is open.
      */
-    public static class CircuitBreakerException extends RuntimeException {
+    public static class CircuitBreakerException extends FireflyException {
         public CircuitBreakerException(String message) {
             super(message);
         }

src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -1,3 +1,4 @@
+org.fireflyframework.transactional.shared.config.TransactionalEngineConfiguration
 org.fireflyframework.transactional.saga.config.SagaPersistenceAutoConfiguration
 org.fireflyframework.transactional.saga.config.SagaRedisAutoConfiguration
 org.fireflyframework.transactional.saga.config.SagaCompositionAutoConfiguration

src/test/java/org/fireflyframework/transactional/persistence/integration/RedisPersistenceIntegrationTest.java

@@ -22,6 +22,8 @@
 import org.fireflyframework.transactional.saga.core.SagaContext;
 import org.fireflyframework.transactional.saga.engine.SagaEngine;
 import org.fireflyframework.transactional.saga.engine.StepInputs;
+import org.fireflyframework.transactional.saga.config.SagaPersistenceAutoConfiguration;
+import org.fireflyframework.transactional.saga.config.SagaRedisAutoConfiguration;
 import org.fireflyframework.transactional.shared.annotations.EnableTransactionalEngine;
 import org.fireflyframework.transactional.shared.core.StepStatus;
 import org.fireflyframework.transactional.saga.persistence.SagaExecutionState;
@@ -34,6 +36,7 @@
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.Primary;
 import org.springframework.data.redis.connection.RedisConnectionFactory;
 import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
@@ -101,6 +104,7 @@ static void configureProperties(DynamicPropertyRegistry registry) {
 
     @Configuration
     @EnableTransactionalEngine
+    @Import({SagaPersistenceAutoConfiguration.class, SagaRedisAutoConfiguration.class})
     static class TestConfig {
 
         @Bean