feat: replace process definition graphs when no instance is running

Co-authored-by: Cursor <cursoragent@cursor.com>

ordo-api/src/main/java/com/jetlumen/ordo/api/OrdoEngine.java

@@ -6,6 +6,12 @@ import java.util.Optional;
 /** Public entry point for definition registration and approval operations. */
 public interface OrdoEngine {
     void register(ProcessDefinition definition);
+
+    /**
+     * Inserts the definition, or replaces its entire graph when the id already exists.
+     * Refuses replacement while any instance of this definition is {@code RUNNING}.
+     */
+    void replace(ProcessDefinition definition);
     default ProcessInstance start(String definitionId, String initiator) {
         return start(definitionId, initiator, ProcessContext.empty());
     }

ordo-api/src/main/java/com/jetlumen/ordo/api/exception/DefinitionInUseException.java

@@ -0,0 +1,7 @@
+package com.jetlumen.ordo.api.exception;
+
+public final class DefinitionInUseException extends OrdoException {
+    public DefinitionInUseException(String definitionId) {
+        super("definition in use: " + definitionId);
+    }
+}

ordo-api/src/main/java/com/jetlumen/ordo/api/repository/ProcessDefinitionRepository.java

@@ -4,7 +4,7 @@ import com.jetlumen.ordo.api.ProcessDefinition;
 
 import java.util.Optional;
 
-/** Storage port for immutable process definitions. */
+/** Storage port for process definitions. */
 public interface ProcessDefinitionRepository {
     /**
      * Inserts the definition if no definition with the same id exists.
@@ -13,5 +13,11 @@ public interface ProcessDefinitionRepository {
      */
     boolean insertIfAbsent(ProcessDefinition definition);
 
+    /**
+     * Inserts the definition, or replaces its name, steps, candidates and transitions
+     * when the id already exists.
+     */
+    void upsert(ProcessDefinition definition);
+
     Optional<ProcessDefinition> findById(String definitionId);
 }

ordo-api/src/main/java/com/jetlumen/ordo/api/repository/ProcessInstanceRepository.java

@@ -13,4 +13,6 @@ public interface ProcessInstanceRepository {
     void update(ProcessInstance instance);
 
     Optional<ProcessInstance> findById(String instanceId);
+
+    boolean existsRunning(String definitionId);
 }