fix(project): preserve completed task history

src/main/java/com/lab/labtimesheet/feature/project/service/ProjectQueryService.java

@@ -71,7 +71,9 @@ public class ProjectQueryService {
     @Transactional(readOnly = true)
     public List<ProjectMemberView> members(long actorUserId, long projectId) {
         var project = visibleProject(actorUserId, projectId);
-        var leaderUserId = project.currentLeader().internUserId();
+        Long leaderUserId = project.status() == ProjectStatus.COMPLETED
+                ? null
+                : project.currentLeader().internUserId();
         return project.memberships().stream()
                 .map(membership -> new ProjectMemberView(
                         membership.id(),
@@ -79,7 +81,9 @@ public class ProjectQueryService {
                         displayName(membership.internUserId()),
                         membership.joinedAt(),
                         membership.leftAt(),
-                        membership.isCurrent() && membership.internUserId() == leaderUserId))
+                        membership.isCurrent()
+                                && leaderUserId != null
+                                && membership.internUserId() == leaderUserId))
                 .toList();
     }
 
@@ -103,6 +107,16 @@ public class ProjectQueryService {
 
     ProjectTaskContext taskContext(long actorUserId, ProjectEntity project) {
         requireVisibleProject(actorUserId, project);
+        if (project.status() == ProjectStatus.COMPLETED) {
+            return new ProjectTaskContext(
+                    project.id(),
+                    project.mentorUserId(),
+                    project.status().name(),
+                    project.startDate(),
+                    project.endDate(),
+                    null,
+                    List.of());
+        }
         var activeMembers = project.memberships().stream()
                 .filter(membership -> membership.isCurrent() && isEligibleIntern(membership.internUserId()))
                 .map(membership -> new ProjectTaskMemberView(

src/test/java/com/lab/labtimesheet/feature/project/service/ProjectServiceIntegrationTest.java

@@ -1,6 +1,7 @@
 package com.lab.labtimesheet.feature.project.service;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -178,6 +179,42 @@ class ProjectServiceIntegrationTest {
         assertEquals(1, projectPages.dashboardSummary(mentorId).distinctActiveMemberCount());
     }
 
+    @Test
+    void completedProjectQueriesReturnHistoricalMembersWithoutRequiringACurrentLeader() {
+        long mentorId = user("mentor-history@example.test", "MENTOR");
+        long leaderId = intern("leader-history@example.test", "I012");
+        long memberId = intern("member-history@example.test", "I013");
+        long projectId = createProject(mentorId, leaderId, "Completed history");
+        projectService.addMember(mentorId, projectId, memberId);
+        var activatedAt = dbTime(NOW.plusSeconds(30));
+        var completedAt = dbTime(NOW.plusSeconds(60));
+        jdbc.update("""
+                update project_leadership_terms
+                set ended_at = ?, ended_by_mentor_user_id = ?
+                where project_id = ? and ended_at is null
+                """, completedAt, mentorId, projectId);
+        jdbc.update("""
+                update project_memberships
+                set left_at = ?, removed_by_mentor_user_id = ?, updated_at = ?
+                where project_id = ? and left_at is null
+                """, completedAt, mentorId, completedAt, projectId);
+        jdbc.update("""
+                update projects
+                set status = 'COMPLETED', activated_at = ?, completed_at = ?, updated_at = ?
+                where id = ?
+                """, activatedAt, completedAt, completedAt, projectId);
+        entityManager.clear();
+
+        var taskContext = projectPages.taskContext(memberId, projectId);
+        assertEquals("COMPLETED", taskContext.status());
+        assertNull(taskContext.currentLeaderMembershipId());
+        assertEquals(List.of(), taskContext.activeMembers());
+        var members = projectPages.members(memberId, projectId);
+        assertEquals(2, members.size());
+        assertTrue(members.stream().allMatch(member -> member.leftAt() != null));
+        assertTrue(members.stream().noneMatch(member -> member.currentLeader()));
+    }
+
     private long createProject(long mentorId, long leaderId, String name) {
         return projectService.create(
                 mentorId,