feat: let the current assignee reassign a pending task

Keep the same task id, move the pending inbox, and record TASK_REASSIGNED without advancing the step.

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

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/JdbcApprovalTaskRepository.java

@@ -27,7 +27,9 @@ public final class JdbcApprovalTaskRepository implements ApprovalTaskRepository
                     + " VALUES (?, ?, ?, ?, ?, ?, ?)";
     private static final String COMPLETE_IF_PENDING =
             "UPDATE ordo_approval_task SET status = ?, completed_at = ?, action_actor = ?, action_comment = ?, action_at = ?"
-                    + " WHERE id = ? AND status = 'PENDING'";
+                    + " WHERE id = ? AND status = 'PENDING' AND assignee = ?";
+    private static final String REASSIGN_IF_PENDING =
+            "UPDATE ordo_approval_task SET assignee = ? WHERE id = ? AND status = 'PENDING' AND assignee = ?";
     private static final String SELECT_TASK =
             "SELECT " + TASK_COLUMNS + " FROM ordo_approval_task WHERE id = ?";
     private static final String SELECT_BY_INSTANCE =
@@ -119,6 +121,24 @@ public final class JdbcApprovalTaskRepository implements ApprovalTaskRepository
         }
     }
 
+    @Override
+    public boolean reassignIfPending(String taskId, String expectedAssignee, String newAssignee) {
+        Objects.requireNonNull(taskId, "taskId must not be null");
+        Objects.requireNonNull(expectedAssignee, "expectedAssignee must not be null");
+        Objects.requireNonNull(newAssignee, "newAssignee must not be null");
+        Connection connection = connectionProvider.getConnection();
+        try (PreparedStatement update = connection.prepareStatement(REASSIGN_IF_PENDING)) {
+            update.setString(1, newAssignee);
+            update.setString(2, taskId);
+            update.setString(3, expectedAssignee);
+            return update.executeUpdate() == 1;
+        } catch (SQLException e) {
+            throw new JdbcStorageException("failed to reassign task: " + taskId, e);
+        } finally {
+            connectionProvider.close(connection);
+        }
+    }
+
     @Override
     public Page<ApprovalTask> query(TaskQuery query, PageRequest pageRequest) {
         Objects.requireNonNull(query, "query must not be null");

ordo-storage-jdbc/src/main/java/com/jetlumen/ordo/storage/jdbc/mapper/ApprovalTaskMapper.java

@@ -40,6 +40,7 @@ public final class ApprovalTaskMapper {
             statement.setTimestamp(5, Timestamp.from(action.operatedAt()));
         }
         statement.setString(6, completedTask.id());
+        statement.setString(7, completedTask.assignee());
     }
 
     public static ApprovalTask read(ResultSet resultSet) throws SQLException {

ordo-storage-jdbc/src/test/java/com/jetlumen/ordo/storage/jdbc/JdbcApprovalTaskRepositoryTest.java

@@ -154,6 +154,70 @@ class JdbcApprovalTaskRepositoryTest {
         assertTrue(Set.of("first", "second").contains(stored.action().comment()));
     }
 
+    @Test
+    void reassignIfPendingUpdatesAssigneeAndFailsWhenNotPending() {
+        ApprovalTask pending = pendingTask("task-1", "inst-1", "manager", "maria", CREATED_AT);
+        repository.save(pending);
+
+        assertTrue(repository.reassignIfPending("task-1", "maria", "diana"));
+        assertEquals("diana", repository.findById("task-1").orElseThrow().assignee());
+        assertEquals(List.of(repository.findById("task-1").orElseThrow()), repository.findPendingByAssignee("diana"));
+        assertTrue(repository.findPendingByAssignee("maria").isEmpty());
+        assertFalse(repository.reassignIfPending("task-1", "maria", "henry"));
+
+        assertTrue(repository.completeIfPending(completedTask(repository.findById("task-1").orElseThrow(), "ok")));
+        assertFalse(repository.reassignIfPending("task-1", "diana", "henry"));
+    }
+
+    @Test
+    void onlyOneOfConcurrentReassignAndCompletionWins() throws Exception {
+        ApprovalTask pending = pendingTask("task-1", "inst-1", "manager", "maria", CREATED_AT);
+        repository.save(pending);
+
+        CountDownLatch start = new CountDownLatch(1);
+        CountDownLatch done = new CountDownLatch(2);
+        AtomicInteger completeWins = new AtomicInteger();
+        AtomicInteger reassignWins = new AtomicInteger();
+        Thread completer = new Thread(() -> {
+            try {
+                start.await();
+                if (repository.completeIfPending(completedTask(pending, "ok"))) {
+                    completeWins.incrementAndGet();
+                }
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            } finally {
+                done.countDown();
+            }
+        });
+        Thread reassigner = new Thread(() -> {
+            try {
+                start.await();
+                if (repository.reassignIfPending("task-1", "maria", "diana")) {
+                    reassignWins.incrementAndGet();
+                }
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            } finally {
+                done.countDown();
+            }
+        });
+        completer.start();
+        reassigner.start();
+        start.countDown();
+
+        assertTrue(done.await(10, TimeUnit.SECONDS));
+        assertEquals(1, completeWins.get() + reassignWins.get());
+        ApprovalTask stored = repository.findById("task-1").orElseThrow();
+        if (completeWins.get() == 1) {
+            assertEquals(TaskStatus.APPROVED, stored.status());
+            assertEquals("maria", stored.assignee());
+        } else {
+            assertEquals(TaskStatus.PENDING, stored.status());
+            assertEquals("diana", stored.assignee());
+        }
+    }
+
     private void attempt(CountDownLatch start, CountDownLatch done, AtomicInteger wins, ApprovalTask completed) {
         try {
             start.await();

ordo-storage-jdbc/src/test/java/com/jetlumen/ordo/storage/jdbc/JdbcOrdoEngineIntegrationTest.java

@@ -97,6 +97,27 @@ class JdbcOrdoEngineIntegrationTest {
         assertEquals("hr", engine.findPendingTasksByInstanceId(instance.id()).get(0).stepId());
     }
 
+    @Test
+    void reassignsAPendingTaskAndRecordsHistory() {
+        ProcessInstance instance = engine.start("leave", "alice");
+        ApprovalTask task = engine.findPendingTasksByInstanceId(instance.id()).get(0);
+
+        ApprovalTask reassigned = engine.reassign(task.id(), "maria", "diana");
+
+        assertEquals("diana", reassigned.assignee());
+        assertEquals(TaskStatus.PENDING, reassigned.status());
+        assertTrue(engine.findPendingTasksByAssignee("maria").isEmpty());
+        assertEquals("diana", engine.findPendingTasksByAssignee("diana").get(0).assignee());
+        List<ProcessEvent> history = engine.queryHistory(instance.id(), new PageRequest(0, 20)).content();
+        ProcessEvent reassignedEvent = history.stream()
+                .filter(event -> event.type() == ProcessEventType.TASK_REASSIGNED)
+                .findFirst()
+                .orElseThrow();
+        assertEquals("maria", reassignedEvent.actor());
+        assertEquals("diana", reassignedEvent.detail());
+        assertEquals(task.id(), reassignedEvent.taskId());
+    }
+
     @Test
     void rollsBackTheWholeApprovalWhenTheNextStepCannotBeCreated() {
         OrdoEngine failingEngine = newEngine((candidate, step, context) -> {