From 25a855ea90dc99aa119d7f0599ab4c68e4f6560b Mon Sep 17 00:00:00 2001
From: sechmachine <97589681+sechmachine727@users.noreply.github.com>
Date: Sat, 15 Aug 2026 00:25:55 +0700
Subject: [PATCH] refactor(project): adopt feature JPA boundaries

---
 .../project/controller/ProjectController.java |  97 ++++++
 .../ProjectAccessDeniedException.java         |   8 +
 .../exception/ProjectControllerAdvice.java    |  21 ++
 .../ProjectRuleViolationException.java        |   8 +
 .../model/ProjectInternEligibility.java       |  14 +
 .../project/model/ProjectLeaderChange.java    |   7 +
 .../project/model}/ProjectStatus.java         |   2 +-
 .../project/model/dto/ProjectActorView.java   |   4 +
 .../model/dto/ProjectCreateCommand.java       |  11 +
 .../project/model/dto/ProjectCreateForm.java  |  30 ++
 .../model/dto/ProjectDashboardSummary.java    |   4 +
 .../project/model/dto/ProjectDetail.java      |  14 +
 .../model/dto/ProjectLeadershipTermView.java  |  10 +
 .../project/model/dto/ProjectMemberForm.java  |   6 +
 .../project/model/dto/ProjectMemberView.java  |  12 +
 .../project/model/dto/ProjectSummary.java     |   6 +
 .../project/model/dto/ProjectTaskContext.java |  18 ++
 .../model/dto/ProjectTaskMemberView.java      |   4 +
 .../project/model/entity/ProjectEntity.java   | 287 ++++++++++++++++++
 .../entity/ProjectLeadershipTermEntity.java   |  93 ++++++
 .../model/entity/ProjectMembershipEntity.java |  79 +++++
 .../project/repository/ProjectRepository.java |  29 ++
 .../project/service/ProjectQueryService.java  | 196 ++++++++++++
 .../project/service/ProjectService.java       |  82 +++++
 .../projects/domain/EligibleIntern.java       |  14 -
 .../projects/domain/LeadershipTerm.java       |  50 ---
 .../labtimesheet/projects/domain/Project.java | 205 -------------
 .../projects/domain/ProjectAccessDenied.java  |   8 -
 .../projects/domain/ProjectMembership.java    |  37 ---
 .../projects/domain/ProjectRuleViolation.java |   8 -
 .../resources/templates/projects/detail.html  |  12 +
 .../resources/templates/projects/form.html    |  19 ++
 .../templates/projects/leadership.html        |  13 +
 .../resources/templates/projects/list.html    |  20 ++
 .../resources/templates/projects/members.html |  13 +
 .../controller/ProjectControllerTest.java     | 142 +++++++++
 .../model/entity/ProjectEntityTest.java}      |  49 +--
 .../ProjectPersistenceStructureTest.java      |  31 ++
 .../ProjectServiceIntegrationTest.java        | 231 ++++++++++++++
 39 files changed, 1549 insertions(+), 345 deletions(-)
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/controller/ProjectController.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectAccessDeniedException.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectControllerAdvice.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectRuleViolationException.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/ProjectInternEligibility.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/ProjectLeaderChange.java
 rename src/main/java/com/lab/labtimesheet/{projects/domain => feature/project/model}/ProjectStatus.java (57%)
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectActorView.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateCommand.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateForm.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDashboardSummary.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDetail.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectLeadershipTermView.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberForm.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberView.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectSummary.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskContext.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskMemberView.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectEntity.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectLeadershipTermEntity.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectMembershipEntity.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/repository/ProjectRepository.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/service/ProjectQueryService.java
 create mode 100644 src/main/java/com/lab/labtimesheet/feature/project/service/ProjectService.java
 delete mode 100644 src/main/java/com/lab/labtimesheet/projects/domain/EligibleIntern.java
 delete mode 100644 src/main/java/com/lab/labtimesheet/projects/domain/LeadershipTerm.java
 delete mode 100644 src/main/java/com/lab/labtimesheet/projects/domain/Project.java
 delete mode 100644 src/main/java/com/lab/labtimesheet/projects/domain/ProjectAccessDenied.java
 delete mode 100644 src/main/java/com/lab/labtimesheet/projects/domain/ProjectMembership.java
 delete mode 100644 src/main/java/com/lab/labtimesheet/projects/domain/ProjectRuleViolation.java
 create mode 100644 src/main/resources/templates/projects/detail.html
 create mode 100644 src/main/resources/templates/projects/form.html
 create mode 100644 src/main/resources/templates/projects/leadership.html
 create mode 100644 src/main/resources/templates/projects/list.html
 create mode 100644 src/main/resources/templates/projects/members.html
 create mode 100644 src/test/java/com/lab/labtimesheet/feature/project/controller/ProjectControllerTest.java
 rename src/test/java/com/lab/labtimesheet/{projects/domain/ProjectTest.java => feature/project/model/entity/ProjectEntityTest.java} (70%)
 create mode 100644 src/test/java/com/lab/labtimesheet/feature/project/repository/ProjectPersistenceStructureTest.java
 create mode 100644 src/test/java/com/lab/labtimesheet/feature/project/service/ProjectServiceIntegrationTest.java

diff --git a/src/main/java/com/lab/labtimesheet/feature/project/controller/ProjectController.java b/src/main/java/com/lab/labtimesheet/feature/project/controller/ProjectController.java
new file mode 100644
index 0000000..16c4758
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/controller/ProjectController.java
@@ -0,0 +1,97 @@
+package com.lab.labtimesheet.feature.project.controller;
+
+import com.lab.labtimesheet.feature.project.model.dto.ProjectCreateForm;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectMemberForm;
+import com.lab.labtimesheet.feature.project.service.ProjectQueryService;
+import com.lab.labtimesheet.feature.project.service.ProjectService;
+import jakarta.validation.Valid;
+import java.security.Principal;
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.validation.BindingResult;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+
+@Controller
+@RequestMapping("/projects")
+public class ProjectController {
+
+    private final ProjectQueryService pages;
+    private final ProjectService projects;
+
+    public ProjectController(ProjectQueryService pages, ProjectService projects) {
+        this.pages = pages;
+        this.projects = projects;
+    }
+
+    @GetMapping
+    public String list(Principal principal, Model model) {
+        model.addAttribute("projects", pages.listVisible(actorId(principal)));
+        return "projects/list";
+    }
+
+    @GetMapping("/new")
+    public String createForm(Model model) {
+        model.addAttribute("projectForm", new ProjectCreateForm());
+        return "projects/form";
+    }
+
+    @PostMapping
+    public String create(
+            Principal principal,
+            @Valid @ModelAttribute("projectForm") ProjectCreateForm projectForm,
+            BindingResult bindingResult) {
+        if (bindingResult.hasErrors()) {
+            return "projects/form";
+        }
+        long projectId = projects.create(actorId(principal), projectForm.toCommand());
+        return "redirect:/projects/" + projectId;
+    }
+
+    @GetMapping("/{projectId}")
+    public String detail(Principal principal, @PathVariable long projectId, Model model) {
+        model.addAttribute("project", pages.detail(actorId(principal), projectId));
+        return "projects/detail";
+    }
+
+    @GetMapping("/{projectId}/members")
+    public String members(Principal principal, @PathVariable long projectId, Model model) {
+        long actorId = actorId(principal);
+        model.addAttribute("project", pages.detail(actorId, projectId));
+        model.addAttribute("members", pages.members(actorId, projectId));
+        return "projects/members";
+    }
+
+    @PostMapping("/{projectId}/members")
+    public String addMember(
+            Principal principal,
+            @PathVariable long projectId,
+            @Valid @ModelAttribute ProjectMemberForm memberForm) {
+        projects.addMember(actorId(principal), projectId, memberForm.internUserId());
+        return "redirect:/projects/" + projectId + "/members";
+    }
+
+    @GetMapping("/{projectId}/leadership")
+    public String leadership(Principal principal, @PathVariable long projectId, Model model) {
+        long actorId = actorId(principal);
+        model.addAttribute("project", pages.detail(actorId, projectId));
+        model.addAttribute("leadership", pages.leadership(actorId, projectId));
+        return "projects/leadership";
+    }
+
+    @PostMapping("/{projectId}/leadership")
+    public String changeLeader(
+            Principal principal,
+            @PathVariable long projectId,
+            @Valid @ModelAttribute ProjectMemberForm memberForm) {
+        projects.changeLeader(actorId(principal), projectId, memberForm.internUserId());
+        return "redirect:/projects/" + projectId + "/leadership";
+    }
+
+    private long actorId(Principal principal) {
+        return pages.authenticatedUserId(principal.getName());
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectAccessDeniedException.java b/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectAccessDeniedException.java
new file mode 100644
index 0000000..65ef0dd
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectAccessDeniedException.java
@@ -0,0 +1,8 @@
+package com.lab.labtimesheet.feature.project.exception;
+
+public final class ProjectAccessDeniedException extends RuntimeException {
+
+    public ProjectAccessDeniedException() {
+        super("Project access denied");
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectControllerAdvice.java b/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectControllerAdvice.java
new file mode 100644
index 0000000..f6c381c
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectControllerAdvice.java
@@ -0,0 +1,21 @@
+package com.lab.labtimesheet.feature.project.exception;
+
+import com.lab.labtimesheet.feature.project.controller.ProjectController;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+@RestControllerAdvice(assignableTypes = ProjectController.class)
+public class ProjectControllerAdvice {
+
+    @ExceptionHandler(ProjectAccessDeniedException.class)
+    @ResponseStatus(HttpStatus.NOT_FOUND)
+    public void accessDenied() {
+    }
+
+    @ExceptionHandler(ProjectRuleViolationException.class)
+    @ResponseStatus(HttpStatus.CONFLICT)
+    public void conflict() {
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectRuleViolationException.java b/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectRuleViolationException.java
new file mode 100644
index 0000000..86d24d6
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/exception/ProjectRuleViolationException.java
@@ -0,0 +1,8 @@
+package com.lab.labtimesheet.feature.project.exception;
+
+public final class ProjectRuleViolationException extends RuntimeException {
+
+    public ProjectRuleViolationException(String message) {
+        super(message);
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectInternEligibility.java b/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectInternEligibility.java
new file mode 100644
index 0000000..63668ed
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectInternEligibility.java
@@ -0,0 +1,14 @@
+package com.lab.labtimesheet.feature.project.model;
+
+public record ProjectInternEligibility(long userId, boolean eligible) {
+
+    public ProjectInternEligibility {
+        if (userId <= 0) {
+            throw new IllegalArgumentException("Intern user ID must be positive");
+        }
+    }
+
+    public boolean isEligible() {
+        return eligible;
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectLeaderChange.java b/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectLeaderChange.java
new file mode 100644
index 0000000..7c1d67d
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectLeaderChange.java
@@ -0,0 +1,7 @@
+package com.lab.labtimesheet.feature.project.model;
+
+import com.lab.labtimesheet.feature.project.model.entity.ProjectMembershipEntity;
+import java.time.Instant;
+
+public record ProjectLeaderChange(ProjectMembershipEntity replacement, Instant effectiveAt) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectStatus.java b/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectStatus.java
similarity index 57%
rename from src/main/java/com/lab/labtimesheet/projects/domain/ProjectStatus.java
rename to src/main/java/com/lab/labtimesheet/feature/project/model/ProjectStatus.java
index 0e24065..75d9e0d 100644
--- a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectStatus.java
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/ProjectStatus.java
@@ -1,4 +1,4 @@
-package com.lab.labtimesheet.projects.domain;
+package com.lab.labtimesheet.feature.project.model;
 
 public enum ProjectStatus {
     PLANNED,
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectActorView.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectActorView.java
new file mode 100644
index 0000000..6139322
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectActorView.java
@@ -0,0 +1,4 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+public record ProjectActorView(long userId, String role) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateCommand.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateCommand.java
new file mode 100644
index 0000000..2c2913f
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateCommand.java
@@ -0,0 +1,11 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import java.time.LocalDate;
+
+public record ProjectCreateCommand(
+        String name,
+        String description,
+        LocalDate startDate,
+        LocalDate endDate,
+        long initialLeaderUserId) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateForm.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateForm.java
new file mode 100644
index 0000000..b95332a
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectCreateForm.java
@@ -0,0 +1,30 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import jakarta.validation.constraints.AssertTrue;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import jakarta.validation.constraints.Size;
+import java.time.LocalDate;
+import org.springframework.format.annotation.DateTimeFormat;
+
+public record ProjectCreateForm(
+        @NotBlank @Size(max = 160) String name,
+        String description,
+        @NotNull @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) LocalDate startDate,
+        @NotNull @DateTimeFormat(iso = DateTimeFormat.ISO.DATE) LocalDate endDate,
+        @NotNull @Positive Long initialLeaderUserId) {
+
+    public ProjectCreateForm() {
+        this(null, null, null, null, null);
+    }
+
+    @AssertTrue(message = "End date must not precede start date")
+    public boolean isDateRangeValid() {
+        return startDate == null || endDate == null || !endDate.isBefore(startDate);
+    }
+
+    public ProjectCreateCommand toCommand() {
+        return new ProjectCreateCommand(name, description, startDate, endDate, initialLeaderUserId);
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDashboardSummary.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDashboardSummary.java
new file mode 100644
index 0000000..8a970f0
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDashboardSummary.java
@@ -0,0 +1,4 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+public record ProjectDashboardSummary(long activeProjectCount, long distinctActiveMemberCount) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDetail.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDetail.java
new file mode 100644
index 0000000..4af0e54
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectDetail.java
@@ -0,0 +1,14 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import java.time.LocalDate;
+
+public record ProjectDetail(
+        long id,
+        String name,
+        String description,
+        String status,
+        LocalDate startDate,
+        LocalDate endDate,
+        String mentorName,
+        String leaderName) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectLeadershipTermView.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectLeadershipTermView.java
new file mode 100644
index 0000000..a63fd92
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectLeadershipTermView.java
@@ -0,0 +1,10 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import java.time.Instant;
+
+public record ProjectLeadershipTermView(
+        long id,
+        String leaderName,
+        Instant startedAt,
+        Instant endedAt) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberForm.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberForm.java
new file mode 100644
index 0000000..13d483c
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberForm.java
@@ -0,0 +1,6 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import jakarta.validation.constraints.Positive;
+
+public record ProjectMemberForm(@Positive long internUserId) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberView.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberView.java
new file mode 100644
index 0000000..b799097
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectMemberView.java
@@ -0,0 +1,12 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import java.time.Instant;
+
+public record ProjectMemberView(
+        long membershipId,
+        long internUserId,
+        String displayName,
+        Instant joinedAt,
+        Instant leftAt,
+        boolean currentLeader) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectSummary.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectSummary.java
new file mode 100644
index 0000000..93de086
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectSummary.java
@@ -0,0 +1,6 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import java.time.LocalDate;
+
+public record ProjectSummary(long id, String name, String status, LocalDate startDate, LocalDate endDate) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskContext.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskContext.java
new file mode 100644
index 0000000..ffb3570
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskContext.java
@@ -0,0 +1,18 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+import java.time.LocalDate;
+import java.util.List;
+
+public record ProjectTaskContext(
+        long projectId,
+        long mentorUserId,
+        String status,
+        LocalDate startDate,
+        LocalDate endDate,
+        Long currentLeaderMembershipId,
+        List<ProjectTaskMemberView> activeMembers) {
+
+    public ProjectTaskContext {
+        activeMembers = List.copyOf(activeMembers);
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskMemberView.java b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskMemberView.java
new file mode 100644
index 0000000..3123f1d
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/dto/ProjectTaskMemberView.java
@@ -0,0 +1,4 @@
+package com.lab.labtimesheet.feature.project.model.dto;
+
+public record ProjectTaskMemberView(long membershipId, long userId, String displayName) {
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectEntity.java b/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectEntity.java
new file mode 100644
index 0000000..eabaefc
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectEntity.java
@@ -0,0 +1,287 @@
+package com.lab.labtimesheet.feature.project.model.entity;
+
+import com.lab.labtimesheet.feature.project.exception.ProjectAccessDeniedException;
+import com.lab.labtimesheet.feature.project.exception.ProjectRuleViolationException;
+import com.lab.labtimesheet.feature.project.model.ProjectInternEligibility;
+import com.lab.labtimesheet.feature.project.model.ProjectLeaderChange;
+import com.lab.labtimesheet.feature.project.model.ProjectStatus;
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.Table;
+import jakarta.persistence.Version;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+@Entity
+@Table(name = "projects")
+public class ProjectEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(name = "mentor_user_id", nullable = false)
+    private long mentorUserId;
+
+    @Column(nullable = false, length = 160)
+    private String name;
+
+    @Column
+    private String description;
+
+    @Column(name = "start_date", nullable = false)
+    private LocalDate startDate;
+
+    @Column(name = "end_date", nullable = false)
+    private LocalDate endDate;
+
+    @OneToMany(mappedBy = "project", cascade = CascadeType.ALL)
+    private List<ProjectMembershipEntity> memberships = new ArrayList<>();
+
+    @OneToMany(mappedBy = "project", cascade = CascadeType.ALL)
+    private List<ProjectLeadershipTermEntity> leadershipTerms = new ArrayList<>();
+
+    @Enumerated(EnumType.STRING)
+    @Column(nullable = false, length = 16)
+    private ProjectStatus status = ProjectStatus.PLANNED;
+
+    @Column(name = "activated_at")
+    private Instant activatedAt;
+
+    @Column(name = "created_at", nullable = false)
+    private Instant createdAt;
+
+    @Column(name = "updated_at", nullable = false)
+    private Instant updatedAt;
+
+    @Version
+    private long version;
+
+    protected ProjectEntity() {
+    }
+
+    private ProjectEntity(
+            long mentorUserId,
+            String name,
+            String description,
+            LocalDate startDate,
+            LocalDate endDate,
+            Instant createdAt) {
+        this.mentorUserId = mentorUserId;
+        this.name = name;
+        this.description = description;
+        this.startDate = startDate;
+        this.endDate = endDate;
+        this.createdAt = createdAt;
+        this.updatedAt = createdAt;
+    }
+
+    public static ProjectEntity plan(
+            long mentorUserId,
+            String name,
+            String description,
+            LocalDate startDate,
+            LocalDate endDate,
+            ProjectInternEligibility initialLeader,
+            Instant at) {
+        if (mentorUserId <= 0) {
+            throw new IllegalArgumentException("Mentor user ID must be positive");
+        }
+        var normalizedName = requireText(name, "Project name is required");
+        Objects.requireNonNull(startDate, "startDate");
+        Objects.requireNonNull(endDate, "endDate");
+        Objects.requireNonNull(at, "at");
+        if (endDate.isBefore(startDate)) {
+            throw new ProjectRuleViolationException("Project end date must not precede its start date");
+        }
+        requireEligible(initialLeader);
+
+        var project = new ProjectEntity(
+                mentorUserId,
+                normalizedName,
+                normalizeOptionalText(description),
+                startDate,
+                endDate,
+                at);
+        var membership = project.addEligibleMember(initialLeader, mentorUserId, at);
+        project.leadershipTerms.add(new ProjectLeadershipTermEntity(project, membership, at, mentorUserId));
+        return project;
+    }
+
+    public ProjectMembershipEntity addMember(
+            long actorMentorUserId, ProjectInternEligibility intern, Instant at) {
+        requireOwner(actorMentorUserId);
+        requireMutable();
+        requireEligible(intern);
+        Objects.requireNonNull(at, "at");
+        if (hasCurrentMember(intern.userId())) {
+            throw new ProjectRuleViolationException("Intern is already a current Project member");
+        }
+        return addEligibleMember(intern, actorMentorUserId, at);
+    }
+
+    public ProjectLeaderChange prepareLeaderChange(
+            long actorMentorUserId, ProjectInternEligibility intern, Instant at) {
+        requireOwner(actorMentorUserId);
+        requireMutable();
+        requireEligible(intern);
+        Objects.requireNonNull(at, "at");
+        var replacement = currentMembership(intern.userId());
+        var current = currentLeadershipTerm();
+        if (current.internUserId() == intern.userId()) {
+            throw new ProjectRuleViolationException("Selected Intern is already the current Leader");
+        }
+
+        var effectiveAt = current.end(at, actorMentorUserId);
+        updatedAt = effectiveAt;
+        return new ProjectLeaderChange(replacement, effectiveAt);
+    }
+
+    public void completeLeaderChange(long actorMentorUserId, ProjectLeaderChange change) {
+        requireOwner(actorMentorUserId);
+        Objects.requireNonNull(change, "change");
+        if (leadershipTerms.stream().anyMatch(ProjectLeadershipTermEntity::isCurrent)) {
+            throw new ProjectRuleViolationException("Current Leader must be closed before replacement");
+        }
+        leadershipTerms.add(new ProjectLeadershipTermEntity(
+                this, change.replacement(), change.effectiveAt(), actorMentorUserId));
+    }
+
+    public void activate(long actorMentorUserId, boolean allTaskAssigneesAreCurrent, Instant at) {
+        requireOwner(actorMentorUserId);
+        Objects.requireNonNull(at, "at");
+        if (status != ProjectStatus.PLANNED) {
+            throw new ProjectRuleViolationException("Only a planned Project can be activated");
+        }
+        if (memberships.stream().noneMatch(ProjectMembershipEntity::isCurrent)
+                || leadershipTerms.stream().noneMatch(ProjectLeadershipTermEntity::isCurrent)) {
+            throw new ProjectRuleViolationException("Project requires a current member and Leader");
+        }
+        if (!allTaskAssigneesAreCurrent) {
+            throw new ProjectRuleViolationException("Every current Task assignee must be an active Project member");
+        }
+        status = ProjectStatus.ACTIVE;
+        activatedAt = at;
+        updatedAt = at;
+    }
+
+    public Long id() {
+        return id;
+    }
+
+    public long mentorUserId() {
+        return mentorUserId;
+    }
+
+    public String name() {
+        return name;
+    }
+
+    public String description() {
+        return description;
+    }
+
+    public LocalDate startDate() {
+        return startDate;
+    }
+
+    public LocalDate endDate() {
+        return endDate;
+    }
+
+    public ProjectStatus status() {
+        return status;
+    }
+
+    public Instant activatedAt() {
+        return activatedAt;
+    }
+
+    public List<ProjectMembershipEntity> memberships() {
+        return List.copyOf(memberships);
+    }
+
+    public List<ProjectLeadershipTermEntity> leadershipTerms() {
+        return List.copyOf(leadershipTerms);
+    }
+
+    public void authorizeOwner(long actorMentorUserId) {
+        requireOwner(actorMentorUserId);
+    }
+
+    public boolean hasCurrentMember(long internUserId) {
+        return memberships.stream()
+                .anyMatch(membership -> membership.internUserId() == internUserId && membership.isCurrent());
+    }
+
+    public boolean hasEverHadMember(long internUserId) {
+        return memberships.stream().anyMatch(membership -> membership.internUserId() == internUserId);
+    }
+
+    public ProjectMembershipEntity currentLeader() {
+        return currentMembership(currentLeadershipTerm().internUserId());
+    }
+
+    private ProjectMembershipEntity addEligibleMember(
+            ProjectInternEligibility intern, long addedByUserId, Instant at) {
+        var membership = new ProjectMembershipEntity(this, intern.userId(), at, addedByUserId);
+        memberships.add(membership);
+        updatedAt = at;
+        return membership;
+    }
+
+    private ProjectMembershipEntity currentMembership(long internUserId) {
+        return memberships.stream()
+                .filter(membership -> membership.internUserId() == internUserId && membership.isCurrent())
+                .findFirst()
+                .orElseThrow(() -> new ProjectRuleViolationException(
+                        "Leader must be a current same-Project member"));
+    }
+
+    private ProjectLeadershipTermEntity currentLeadershipTerm() {
+        return leadershipTerms.stream()
+                .filter(ProjectLeadershipTermEntity::isCurrent)
+                .findFirst()
+                .orElseThrow(() -> new ProjectRuleViolationException("Project has no current Leader"));
+    }
+
+    private void requireOwner(long actorMentorUserId) {
+        if (mentorUserId != actorMentorUserId) {
+            throw new ProjectAccessDeniedException();
+        }
+    }
+
+    private void requireMutable() {
+        if (status == ProjectStatus.COMPLETED) {
+            throw new ProjectRuleViolationException("Completed Projects are read-only");
+        }
+    }
+
+    private static void requireEligible(ProjectInternEligibility intern) {
+        Objects.requireNonNull(intern, "intern");
+        if (!intern.isEligible()) {
+            throw new ProjectRuleViolationException("Intern must have an active account and internship");
+        }
+    }
+
+    private static String requireText(String value, String message) {
+        if (value == null || value.trim().isEmpty()) {
+            throw new ProjectRuleViolationException(message);
+        }
+        return value.trim();
+    }
+
+    private static String normalizeOptionalText(String value) {
+        return value == null || value.trim().isEmpty() ? null : value.trim();
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectLeadershipTermEntity.java b/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectLeadershipTermEntity.java
new file mode 100644
index 0000000..62974e5
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectLeadershipTermEntity.java
@@ -0,0 +1,93 @@
+package com.lab.labtimesheet.feature.project.model.entity;
+
+import com.lab.labtimesheet.feature.project.exception.ProjectRuleViolationException;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+import java.time.Instant;
+
+@Entity
+@Table(name = "project_leadership_terms")
+public class ProjectLeadershipTermEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @JoinColumn(name = "project_id", nullable = false)
+    private ProjectEntity project;
+
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @JoinColumn(name = "membership_id", nullable = false)
+    private ProjectMembershipEntity membership;
+
+    @Column(name = "started_at", nullable = false)
+    private Instant startedAt;
+
+    @Column(name = "appointed_by_mentor_user_id", nullable = false)
+    private long appointedByMentorUserId;
+
+    @Column(name = "ended_at")
+    private Instant endedAt;
+
+    @Column(name = "ended_by_mentor_user_id")
+    private Long endedByMentorUserId;
+
+    protected ProjectLeadershipTermEntity() {
+    }
+
+    ProjectLeadershipTermEntity(
+            ProjectEntity project,
+            ProjectMembershipEntity membership,
+            Instant startedAt,
+            long appointedByMentorUserId) {
+        this.project = project;
+        this.membership = membership;
+        this.startedAt = startedAt;
+        this.appointedByMentorUserId = appointedByMentorUserId;
+    }
+
+    public Long id() {
+        return id;
+    }
+
+    public long internUserId() {
+        return membership.internUserId();
+    }
+
+    public Instant startedAt() {
+        return startedAt;
+    }
+
+    public long appointedByMentorUserId() {
+        return appointedByMentorUserId;
+    }
+
+    public Instant endedAt() {
+        return endedAt;
+    }
+
+    public Long endedByMentorUserId() {
+        return endedByMentorUserId;
+    }
+
+    public boolean isCurrent() {
+        return endedAt == null;
+    }
+
+    Instant end(Instant at, long mentorUserId) {
+        if (!isCurrent() || at.isBefore(startedAt)) {
+            throw new ProjectRuleViolationException("Leadership term end must follow its start");
+        }
+        endedAt = at.equals(startedAt) ? startedAt.plusNanos(1_000) : at;
+        endedByMentorUserId = mentorUserId;
+        return endedAt;
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectMembershipEntity.java b/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectMembershipEntity.java
new file mode 100644
index 0000000..59f158c
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/model/entity/ProjectMembershipEntity.java
@@ -0,0 +1,79 @@
+package com.lab.labtimesheet.feature.project.model.entity;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.Table;
+import jakarta.persistence.Version;
+import java.time.Instant;
+
+@Entity
+@Table(name = "project_memberships")
+public class ProjectMembershipEntity {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @JoinColumn(name = "project_id", nullable = false)
+    private ProjectEntity project;
+
+    @Column(name = "intern_user_id", nullable = false)
+    private long internUserId;
+
+    @Column(name = "joined_at", nullable = false)
+    private Instant joinedAt;
+
+    @Column(name = "added_by_user_id", nullable = false)
+    private long addedByUserId;
+
+    @Column(name = "left_at")
+    private Instant leftAt;
+
+    @Column(name = "updated_at", nullable = false)
+    private Instant updatedAt;
+
+    @Version
+    private long version;
+
+    protected ProjectMembershipEntity() {
+    }
+
+    ProjectMembershipEntity(ProjectEntity project, long internUserId, Instant joinedAt, long addedByUserId) {
+        this.project = project;
+        this.internUserId = internUserId;
+        this.joinedAt = joinedAt;
+        this.addedByUserId = addedByUserId;
+        this.updatedAt = joinedAt;
+    }
+
+    public Long id() {
+        return id;
+    }
+
+    public long internUserId() {
+        return internUserId;
+    }
+
+    public Instant joinedAt() {
+        return joinedAt;
+    }
+
+    public long addedByUserId() {
+        return addedByUserId;
+    }
+
+    public Instant leftAt() {
+        return leftAt;
+    }
+
+    public boolean isCurrent() {
+        return leftAt == null;
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/repository/ProjectRepository.java b/src/main/java/com/lab/labtimesheet/feature/project/repository/ProjectRepository.java
new file mode 100644
index 0000000..c0be117
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/repository/ProjectRepository.java
@@ -0,0 +1,29 @@
+package com.lab.labtimesheet.feature.project.repository;
+
+import com.lab.labtimesheet.feature.project.model.entity.ProjectEntity;
+import jakarta.persistence.LockModeType;
+import java.util.List;
+import java.util.Optional;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+
+public interface ProjectRepository extends JpaRepository<ProjectEntity, Long> {
+
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    @Query("select project from ProjectEntity project where project.id = :id")
+    Optional<ProjectEntity> findLockedById(@Param("id") long id);
+
+    List<ProjectEntity> findAllByOrderByUpdatedAtDescIdDesc();
+
+    List<ProjectEntity> findByMentorUserIdOrderByUpdatedAtDescIdDesc(long mentorUserId);
+
+    @Query("""
+            select distinct project from ProjectEntity project
+            join project.memberships membership
+            where membership.internUserId = :internUserId
+            order by project.updatedAt desc, project.id desc
+            """)
+    List<ProjectEntity> findVisibleToIntern(@Param("internUserId") long internUserId);
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/service/ProjectQueryService.java b/src/main/java/com/lab/labtimesheet/feature/project/service/ProjectQueryService.java
new file mode 100644
index 0000000..eadff93
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/service/ProjectQueryService.java
@@ -0,0 +1,196 @@
+package com.lab.labtimesheet.feature.project.service;
+
+import com.lab.labtimesheet.feature.account.model.dto.AccountIdentity;
+import com.lab.labtimesheet.feature.account.service.AccountService;
+import com.lab.labtimesheet.feature.project.exception.ProjectAccessDeniedException;
+import com.lab.labtimesheet.feature.project.model.ProjectStatus;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectDetail;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectActorView;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectDashboardSummary;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectLeadershipTermView;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectMemberView;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectSummary;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectTaskContext;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectTaskMemberView;
+import com.lab.labtimesheet.feature.project.model.entity.ProjectEntity;
+import com.lab.labtimesheet.feature.project.repository.ProjectRepository;
+import java.util.List;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class ProjectQueryService {
+
+    private final ProjectRepository projects;
+    private final AccountService accounts;
+
+    public ProjectQueryService(ProjectRepository projects, AccountService accounts) {
+        this.projects = projects;
+        this.accounts = accounts;
+    }
+
+    @Transactional(readOnly = true)
+    public long authenticatedUserId(String email) {
+        return authenticatedActor(email).userId();
+    }
+
+    @Transactional(readOnly = true)
+    public ProjectActorView authenticatedActor(String email) {
+        try {
+            var actor = accounts.requireIdentityByEmail(email);
+            if (!"ACTIVE".equals(actor.status().name())) {
+                throw new ProjectAccessDeniedException();
+            }
+            return new ProjectActorView(actor.id(), actor.role().name());
+        } catch (IllegalArgumentException exception) {
+            throw new ProjectAccessDeniedException();
+        }
+    }
+
+    @Transactional(readOnly = true)
+    public List<ProjectSummary> listVisible(long actorUserId) {
+        var actor = activeActor(actorUserId);
+        return visibleProjects(actor, actorUserId).stream().map(ProjectQueryService::summary).toList();
+    }
+
+    @Transactional(readOnly = true)
+    public ProjectDetail detail(long actorUserId, long projectId) {
+        var project = visibleProject(actorUserId, projectId);
+        return new ProjectDetail(
+                project.id(),
+                project.name(),
+                project.description(),
+                project.status().name(),
+                project.startDate(),
+                project.endDate(),
+                displayName(project.mentorUserId()),
+                displayName(project.currentLeader().internUserId()));
+    }
+
+    @Transactional(readOnly = true)
+    public List<ProjectMemberView> members(long actorUserId, long projectId) {
+        var project = visibleProject(actorUserId, projectId);
+        var leaderUserId = project.currentLeader().internUserId();
+        return project.memberships().stream()
+                .map(membership -> new ProjectMemberView(
+                        membership.id(),
+                        membership.internUserId(),
+                        displayName(membership.internUserId()),
+                        membership.joinedAt(),
+                        membership.leftAt(),
+                        membership.isCurrent() && membership.internUserId() == leaderUserId))
+                .toList();
+    }
+
+    @Transactional(readOnly = true)
+    public List<ProjectLeadershipTermView> leadership(long actorUserId, long projectId) {
+        return visibleProject(actorUserId, projectId).leadershipTerms().stream()
+                .sorted((left, right) -> right.startedAt().compareTo(left.startedAt()))
+                .map(term -> new ProjectLeadershipTermView(
+                        term.id(),
+                        displayName(term.internUserId()),
+                        term.startedAt(),
+                        term.endedAt()))
+                .toList();
+    }
+
+    @Transactional(readOnly = true)
+    public ProjectTaskContext taskContext(long actorUserId, long projectId) {
+        var project = visibleProject(actorUserId, projectId);
+        var activeMembers = project.memberships().stream()
+                .filter(membership -> membership.isCurrent() && isEligibleIntern(membership.internUserId()))
+                .map(membership -> new ProjectTaskMemberView(
+                        membership.id(),
+                        membership.internUserId(),
+                        displayName(membership.internUserId())))
+                .toList();
+        var currentLeader = project.currentLeader();
+        var currentLeaderMembershipId = activeMembers.stream()
+                .filter(member -> member.membershipId() == currentLeader.id())
+                .map(ProjectTaskMemberView::membershipId)
+                .findFirst()
+                .orElse(null);
+        return new ProjectTaskContext(
+                project.id(),
+                project.mentorUserId(),
+                project.status().name(),
+                project.startDate(),
+                project.endDate(),
+                currentLeaderMembershipId,
+                activeMembers);
+    }
+
+    @Transactional(readOnly = true)
+    public ProjectDashboardSummary dashboardSummary(long actorUserId) {
+        var actor = activeActor(actorUserId);
+        var activeProjects = visibleProjects(actor, actorUserId).stream()
+                .filter(project -> project.status() == ProjectStatus.ACTIVE)
+                .filter(project -> !"INTERN".equals(actor.role().name())
+                        || (accounts.isEligibleIntern(actorUserId) && project.hasCurrentMember(actorUserId)))
+                .toList();
+        var distinctActiveMembers = "MENTOR".equals(actor.role().name())
+                ? activeProjects.stream()
+                        .flatMap(project -> project.memberships().stream())
+                        .filter(membership -> membership.isCurrent()
+                                && accounts.isEligibleIntern(membership.internUserId()))
+                        .map(membership -> membership.internUserId())
+                        .distinct()
+                        .count()
+                : 0L;
+        return new ProjectDashboardSummary(activeProjects.size(), distinctActiveMembers);
+    }
+
+    private ProjectEntity visibleProject(long actorUserId, long projectId) {
+        var actor = activeActor(actorUserId);
+        var project = projects.findById(projectId).orElseThrow(ProjectAccessDeniedException::new);
+        var visible = "ADMIN".equals(actor.role().name())
+                || ("MENTOR".equals(actor.role().name()) && project.mentorUserId() == actorUserId)
+                || ("INTERN".equals(actor.role().name()) && project.hasEverHadMember(actorUserId));
+        if (!visible) {
+            throw new ProjectAccessDeniedException();
+        }
+        return project;
+    }
+
+    private List<ProjectEntity> visibleProjects(AccountIdentity actor, long actorUserId) {
+        return switch (actor.role().name()) {
+            case "ADMIN" -> projects.findAllByOrderByUpdatedAtDescIdDesc();
+            case "MENTOR" -> projects.findByMentorUserIdOrderByUpdatedAtDescIdDesc(actorUserId);
+            case "INTERN" -> projects.findVisibleToIntern(actorUserId);
+            default -> throw new ProjectAccessDeniedException();
+        };
+    }
+
+    private AccountIdentity activeActor(long actorUserId) {
+        try {
+            var actor = accounts.requireIdentityById(actorUserId);
+            if (!"ACTIVE".equals(actor.status().name())) {
+                throw new ProjectAccessDeniedException();
+            }
+            return actor;
+        } catch (IllegalArgumentException exception) {
+            throw new ProjectAccessDeniedException();
+        }
+    }
+
+    private String displayName(long userId) {
+        try {
+            return accounts.requireIdentityById(userId).displayName();
+        } catch (IllegalArgumentException exception) {
+            throw new ProjectAccessDeniedException();
+        }
+    }
+
+    private boolean isEligibleIntern(long userId) {
+        return accounts.isEligibleIntern(userId);
+    }
+
+    private static ProjectSummary summary(ProjectEntity project) {
+        return new ProjectSummary(
+                project.id(),
+                project.name(),
+                project.status().name(),
+                project.startDate(),
+                project.endDate());
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/feature/project/service/ProjectService.java b/src/main/java/com/lab/labtimesheet/feature/project/service/ProjectService.java
new file mode 100644
index 0000000..31c994f
--- /dev/null
+++ b/src/main/java/com/lab/labtimesheet/feature/project/service/ProjectService.java
@@ -0,0 +1,82 @@
+package com.lab.labtimesheet.feature.project.service;
+
+import com.lab.labtimesheet.feature.project.exception.ProjectAccessDeniedException;
+import com.lab.labtimesheet.feature.account.service.AccountService;
+import com.lab.labtimesheet.feature.project.model.ProjectInternEligibility;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectCreateCommand;
+import com.lab.labtimesheet.feature.project.model.entity.ProjectEntity;
+import com.lab.labtimesheet.feature.project.repository.ProjectRepository;
+import java.time.Clock;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class ProjectService {
+
+    private final ProjectRepository projects;
+    private final AccountService accounts;
+    private final Clock clock;
+
+    public ProjectService(
+            ProjectRepository projects,
+            AccountService accounts,
+            Clock clock) {
+        this.projects = projects;
+        this.accounts = accounts;
+        this.clock = clock;
+    }
+
+    @Transactional
+    public long create(long actorUserId, ProjectCreateCommand command) {
+        requireActiveMentor(actorUserId);
+        var project = ProjectEntity.plan(
+                actorUserId,
+                command.name(),
+                command.description(),
+                command.startDate(),
+                command.endDate(),
+                eligibleIntern(command.initialLeaderUserId()),
+                clock.instant());
+        return projects.saveAndFlush(project).id();
+    }
+
+    @Transactional
+    public void addMember(long actorUserId, long projectId, long internUserId) {
+        var project = lockedProject(projectId);
+        project.authorizeOwner(actorUserId);
+        project.addMember(actorUserId, eligibleIntern(internUserId), clock.instant());
+        projects.flush();
+    }
+
+    @Transactional
+    public void changeLeader(long actorUserId, long projectId, long internUserId) {
+        var project = lockedProject(projectId);
+        project.authorizeOwner(actorUserId);
+        var change = project.prepareLeaderChange(actorUserId, eligibleIntern(internUserId), clock.instant());
+
+        // PostgreSQL rejects overlapping terms immediately. Flush the old term's
+        // end before inserting its replacement; the transaction remains atomic.
+        projects.flush();
+        project.completeLeaderChange(actorUserId, change);
+        projects.flush();
+    }
+
+    private ProjectEntity lockedProject(long projectId) {
+        return projects.findLockedById(projectId).orElseThrow(ProjectAccessDeniedException::new);
+    }
+
+    private ProjectInternEligibility eligibleIntern(long userId) {
+        return new ProjectInternEligibility(userId, accounts.isEligibleIntern(userId));
+    }
+
+    private void requireActiveMentor(long userId) {
+        try {
+            var identity = accounts.requireIdentityById(userId);
+            if (!"MENTOR".equals(identity.role().name()) || !"ACTIVE".equals(identity.status().name())) {
+                throw new ProjectAccessDeniedException();
+            }
+        } catch (IllegalArgumentException exception) {
+            throw new ProjectAccessDeniedException();
+        }
+    }
+}
diff --git a/src/main/java/com/lab/labtimesheet/projects/domain/EligibleIntern.java b/src/main/java/com/lab/labtimesheet/projects/domain/EligibleIntern.java
deleted file mode 100644
index 47777c2..0000000
--- a/src/main/java/com/lab/labtimesheet/projects/domain/EligibleIntern.java
+++ /dev/null
@@ -1,14 +0,0 @@
-package com.lab.labtimesheet.projects.domain;
-
-public record EligibleIntern(long userId, boolean accountActive, boolean internshipActive) {
-
-    public EligibleIntern {
-        if (userId <= 0) {
-            throw new IllegalArgumentException("Intern user ID must be positive");
-        }
-    }
-
-    public boolean isEligible() {
-        return accountActive && internshipActive;
-    }
-}
diff --git a/src/main/java/com/lab/labtimesheet/projects/domain/LeadershipTerm.java b/src/main/java/com/lab/labtimesheet/projects/domain/LeadershipTerm.java
deleted file mode 100644
index b91850a..0000000
--- a/src/main/java/com/lab/labtimesheet/projects/domain/LeadershipTerm.java
+++ /dev/null
@@ -1,50 +0,0 @@
-package com.lab.labtimesheet.projects.domain;
-
-import java.time.Instant;
-
-public final class LeadershipTerm {
-
-    private final ProjectMembership membership;
-    private final Instant startedAt;
-    private final long appointedByMentorUserId;
-    private Instant endedAt;
-    private Long endedByMentorUserId;
-
-    LeadershipTerm(ProjectMembership membership, Instant startedAt, long appointedByMentorUserId) {
-        this.membership = membership;
-        this.startedAt = startedAt;
-        this.appointedByMentorUserId = appointedByMentorUserId;
-    }
-
-    public long internUserId() {
-        return membership.internUserId();
-    }
-
-    public Instant startedAt() {
-        return startedAt;
-    }
-
-    public long appointedByMentorUserId() {
-        return appointedByMentorUserId;
-    }
-
-    public Instant endedAt() {
-        return endedAt;
-    }
-
-    public Long endedByMentorUserId() {
-        return endedByMentorUserId;
-    }
-
-    public boolean isCurrent() {
-        return endedAt == null;
-    }
-
-    void end(Instant at, long mentorUserId) {
-        if (!isCurrent() || !at.isAfter(startedAt)) {
-            throw new ProjectRuleViolation("Leadership term end must follow its start");
-        }
-        endedAt = at;
-        endedByMentorUserId = mentorUserId;
-    }
-}
diff --git a/src/main/java/com/lab/labtimesheet/projects/domain/Project.java b/src/main/java/com/lab/labtimesheet/projects/domain/Project.java
deleted file mode 100644
index e81fa40..0000000
--- a/src/main/java/com/lab/labtimesheet/projects/domain/Project.java
+++ /dev/null
@@ -1,205 +0,0 @@
-package com.lab.labtimesheet.projects.domain;
-
-import java.time.Instant;
-import java.time.LocalDate;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Objects;
-
-public final class Project {
-
-    private final long mentorUserId;
-    private final String name;
-    private final String description;
-    private final LocalDate startDate;
-    private final LocalDate endDate;
-    private final List<ProjectMembership> memberships = new ArrayList<>();
-    private final List<LeadershipTerm> leadershipTerms = new ArrayList<>();
-    private ProjectStatus status = ProjectStatus.PLANNED;
-    private Instant activatedAt;
-
-    private Project(
-            long mentorUserId,
-            String name,
-            String description,
-            LocalDate startDate,
-            LocalDate endDate) {
-        this.mentorUserId = mentorUserId;
-        this.name = name;
-        this.description = description;
-        this.startDate = startDate;
-        this.endDate = endDate;
-    }
-
-    public static Project plan(
-            long mentorUserId,
-            String name,
-            String description,
-            LocalDate startDate,
-            LocalDate endDate,
-            EligibleIntern initialLeader,
-            Instant at) {
-        if (mentorUserId <= 0) {
-            throw new IllegalArgumentException("Mentor user ID must be positive");
-        }
-        var normalizedName = requireText(name, "Project name is required");
-        Objects.requireNonNull(startDate, "startDate");
-        Objects.requireNonNull(endDate, "endDate");
-        Objects.requireNonNull(at, "at");
-        if (endDate.isBefore(startDate)) {
-            throw new ProjectRuleViolation("Project end date must not precede its start date");
-        }
-        requireEligible(initialLeader);
-
-        var project = new Project(
-                mentorUserId,
-                normalizedName,
-                normalizeOptionalText(description),
-                startDate,
-                endDate);
-        var membership = project.addEligibleMember(initialLeader, mentorUserId, at);
-        project.leadershipTerms.add(new LeadershipTerm(membership, at, mentorUserId));
-        return project;
-    }
-
-    public ProjectMembership addMember(long actorMentorUserId, EligibleIntern intern, Instant at) {
-        requireOwner(actorMentorUserId);
-        requireMutable();
-        requireEligible(intern);
-        Objects.requireNonNull(at, "at");
-        if (hasCurrentMember(intern.userId())) {
-            throw new ProjectRuleViolation("Intern is already a current Project member");
-        }
-        return addEligibleMember(intern, actorMentorUserId, at);
-    }
-
-    public void changeLeader(long actorMentorUserId, EligibleIntern intern, Instant at) {
-        requireOwner(actorMentorUserId);
-        requireMutable();
-        requireEligible(intern);
-        Objects.requireNonNull(at, "at");
-        var replacement = currentMembership(intern.userId());
-        var current = currentLeadershipTerm();
-        if (current.internUserId() == intern.userId()) {
-            throw new ProjectRuleViolation("Selected Intern is already the current Leader");
-        }
-
-        current.end(at, actorMentorUserId);
-        leadershipTerms.add(new LeadershipTerm(replacement, at, actorMentorUserId));
-    }
-
-    public void activate(long actorMentorUserId, boolean allTaskAssigneesAreCurrent, Instant at) {
-        requireOwner(actorMentorUserId);
-        Objects.requireNonNull(at, "at");
-        if (status != ProjectStatus.PLANNED) {
-            throw new ProjectRuleViolation("Only a planned Project can be activated");
-        }
-        if (memberships.stream().noneMatch(ProjectMembership::isCurrent)
-                || leadershipTerms.stream().noneMatch(LeadershipTerm::isCurrent)) {
-            throw new ProjectRuleViolation("Project requires a current member and Leader");
-        }
-        if (!allTaskAssigneesAreCurrent) {
-            throw new ProjectRuleViolation("Every current Task assignee must be an active Project member");
-        }
-        status = ProjectStatus.ACTIVE;
-        activatedAt = at;
-    }
-
-    public long mentorUserId() {
-        return mentorUserId;
-    }
-
-    public String name() {
-        return name;
-    }
-
-    public String description() {
-        return description;
-    }
-
-    public LocalDate startDate() {
-        return startDate;
-    }
-
-    public LocalDate endDate() {
-        return endDate;
-    }
-
-    public ProjectStatus status() {
-        return status;
-    }
-
-    public Instant activatedAt() {
-        return activatedAt;
-    }
-
-    public List<ProjectMembership> memberships() {
-        return List.copyOf(memberships);
-    }
-
-    public List<LeadershipTerm> leadershipTerms() {
-        return List.copyOf(leadershipTerms);
-    }
-
-    public boolean hasCurrentMember(long internUserId) {
-        return memberships.stream()
-                .anyMatch(membership -> membership.internUserId() == internUserId && membership.isCurrent());
-    }
-
-    public ProjectMembership currentLeader() {
-        return currentMembership(currentLeadershipTerm().internUserId());
-    }
-
-    private ProjectMembership addEligibleMember(EligibleIntern intern, long addedByUserId, Instant at) {
-        var membership = new ProjectMembership(intern.userId(), at, addedByUserId);
-        memberships.add(membership);
-        return membership;
-    }
-
-    private ProjectMembership currentMembership(long internUserId) {
-        return memberships.stream()
-                .filter(membership -> membership.internUserId() == internUserId && membership.isCurrent())
-                .findFirst()
-                .orElseThrow(() -> new ProjectRuleViolation("Leader must be a current same-Project member"));
-    }
-
-    private LeadershipTerm currentLeadershipTerm() {
-        return leadershipTerms.stream()
-                .filter(LeadershipTerm::isCurrent)
-                .findFirst()
-                .orElseThrow(() -> new ProjectRuleViolation("Project has no current Leader"));
-    }
-
-    private void requireOwner(long actorMentorUserId) {
-        if (mentorUserId != actorMentorUserId) {
-            throw new ProjectAccessDenied();
-        }
-    }
-
-    private void requireMutable() {
-        if (status == ProjectStatus.COMPLETED) {
-            throw new ProjectRuleViolation("Completed Projects are read-only");
-        }
-    }
-
-    private static void requireEligible(EligibleIntern intern) {
-        Objects.requireNonNull(intern, "intern");
-        if (!intern.isEligible()) {
-            throw new ProjectRuleViolation("Intern must have an active account and internship");
-        }
-    }
-
-    private static String requireText(String value, String message) {
-        if (value == null || value.trim().isEmpty()) {
-            throw new ProjectRuleViolation(message);
-        }
-        return value.trim();
-    }
-
-    private static String normalizeOptionalText(String value) {
-        if (value == null || value.trim().isEmpty()) {
-            return null;
-        }
-        return value.trim();
-    }
-}
diff --git a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectAccessDenied.java b/src/main/java/com/lab/labtimesheet/projects/domain/ProjectAccessDenied.java
deleted file mode 100644
index c60789a..0000000
--- a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectAccessDenied.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package com.lab.labtimesheet.projects.domain;
-
-public final class ProjectAccessDenied extends RuntimeException {
-
-    public ProjectAccessDenied() {
-        super("Project access denied");
-    }
-}
diff --git a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectMembership.java b/src/main/java/com/lab/labtimesheet/projects/domain/ProjectMembership.java
deleted file mode 100644
index a48b86a..0000000
--- a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectMembership.java
+++ /dev/null
@@ -1,37 +0,0 @@
-package com.lab.labtimesheet.projects.domain;
-
-import java.time.Instant;
-
-public final class ProjectMembership {
-
-    private final long internUserId;
-    private final Instant joinedAt;
-    private final long addedByUserId;
-    private Instant leftAt;
-
-    ProjectMembership(long internUserId, Instant joinedAt, long addedByUserId) {
-        this.internUserId = internUserId;
-        this.joinedAt = joinedAt;
-        this.addedByUserId = addedByUserId;
-    }
-
-    public long internUserId() {
-        return internUserId;
-    }
-
-    public Instant joinedAt() {
-        return joinedAt;
-    }
-
-    public long addedByUserId() {
-        return addedByUserId;
-    }
-
-    public Instant leftAt() {
-        return leftAt;
-    }
-
-    public boolean isCurrent() {
-        return leftAt == null;
-    }
-}
diff --git a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectRuleViolation.java b/src/main/java/com/lab/labtimesheet/projects/domain/ProjectRuleViolation.java
deleted file mode 100644
index 4357c9c..0000000
--- a/src/main/java/com/lab/labtimesheet/projects/domain/ProjectRuleViolation.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package com.lab.labtimesheet.projects.domain;
-
-public final class ProjectRuleViolation extends RuntimeException {
-
-    public ProjectRuleViolation(String message) {
-        super(message);
-    }
-}
diff --git a/src/main/resources/templates/projects/detail.html b/src/main/resources/templates/projects/detail.html
new file mode 100644
index 0000000..5dd745e
--- /dev/null
+++ b/src/main/resources/templates/projects/detail.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
+<head><meta charset="utf-8"><title th:text="${project.name}">Project</title></head>
+<body>
+<main>
+  <h1 th:text="${project.name}">Project</h1>
+  <p th:text="${project.description}"></p>
+  <dl><dt>Status</dt><dd th:text="${project.status}"></dd><dt>Mentor</dt><dd th:text="${project.mentorName}"></dd><dt>Leader</dt><dd th:text="${project.leaderName}"></dd></dl>
+  <nav aria-label="Project sections"><a th:href="@{/projects/{id}/members(id=${project.id})}">Members</a> <a th:href="@{/projects/{id}/leadership(id=${project.id})}">Leadership</a></nav>
+</main>
+</body>
+</html>
diff --git a/src/main/resources/templates/projects/form.html b/src/main/resources/templates/projects/form.html
new file mode 100644
index 0000000..2834cfa
--- /dev/null
+++ b/src/main/resources/templates/projects/form.html
@@ -0,0 +1,19 @@
+<!doctype html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
+<head><meta charset="utf-8"><title>Create Project</title></head>
+<body>
+<main>
+  <h1>Create Project</h1>
+  <form method="post" th:action="@{/projects}" th:object="${projectForm}">
+    <label for="name">Name</label><input id="name" th:field="*{name}" required maxlength="160">
+    <p th:errors="*{name}"></p>
+    <label for="description">Description</label><textarea id="description" th:field="*{description}"></textarea>
+    <label for="startDate">Start date</label><input id="startDate" type="date" th:field="*{startDate}" required>
+    <label for="endDate">End date</label><input id="endDate" type="date" th:field="*{endDate}" required>
+    <label for="leader">Initial Leader user ID</label><input id="leader" type="number" min="1" th:field="*{initialLeaderUserId}" required>
+    <p th:errors="*{initialLeaderUserId}"></p>
+    <button type="submit">Create Project</button>
+  </form>
+</main>
+</body>
+</html>
diff --git a/src/main/resources/templates/projects/leadership.html b/src/main/resources/templates/projects/leadership.html
new file mode 100644
index 0000000..378a69c
--- /dev/null
+++ b/src/main/resources/templates/projects/leadership.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
+<head><meta charset="utf-8"><title>Project leadership</title></head>
+<body>
+<main>
+  <h1><span th:text="${project.name}">Project</span> leadership</h1>
+  <table><caption>Leadership history</caption><thead><tr><th scope="col">Leader</th><th scope="col">Started</th><th scope="col">Ended</th></tr></thead>
+    <tbody><tr th:each="term : ${leadership}"><td th:text="${term.leaderName}"></td><td th:text="${term.startedAt}"></td><td th:text="${term.endedAt}"></td></tr></tbody>
+  </table>
+  <form method="post" th:action="@{/projects/{id}/leadership(id=${project.id})}"><label for="leader">New Leader user ID</label><input id="leader" name="internUserId" type="number" min="1" required><button type="submit">Change Leader</button></form>
+</main>
+</body>
+</html>
diff --git a/src/main/resources/templates/projects/list.html b/src/main/resources/templates/projects/list.html
new file mode 100644
index 0000000..9379ac8
--- /dev/null
+++ b/src/main/resources/templates/projects/list.html
@@ -0,0 +1,20 @@
+<!doctype html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
+<head><meta charset="utf-8"><title>Projects</title></head>
+<body>
+<main>
+  <h1>Projects</h1>
+  <a href="/projects/new">Create Project</a>
+  <p th:if="${#lists.isEmpty(projects)}">No authorized Projects.</p>
+  <table th:unless="${#lists.isEmpty(projects)}">
+    <caption>Authorized Projects</caption>
+    <thead><tr><th scope="col">Name</th><th scope="col">Status</th><th scope="col">Dates</th></tr></thead>
+    <tbody><tr th:each="project : ${projects}">
+      <td><a th:href="@{/projects/{id}(id=${project.id})}" th:text="${project.name}">Project</a></td>
+      <td th:text="${project.status}">PLANNED</td>
+      <td><span th:text="${project.startDate}">Start</span> – <span th:text="${project.endDate}">End</span></td>
+    </tr></tbody>
+  </table>
+</main>
+</body>
+</html>
diff --git a/src/main/resources/templates/projects/members.html b/src/main/resources/templates/projects/members.html
new file mode 100644
index 0000000..e0238eb
--- /dev/null
+++ b/src/main/resources/templates/projects/members.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org">
+<head><meta charset="utf-8"><title>Project members</title></head>
+<body>
+<main>
+  <h1><span th:text="${project.name}">Project</span> members</h1>
+  <table><caption>Membership history</caption><thead><tr><th scope="col">Intern</th><th scope="col">Joined</th><th scope="col">Left</th><th scope="col">Role</th></tr></thead>
+    <tbody><tr th:each="member : ${members}"><td th:text="${member.displayName}"></td><td th:text="${member.joinedAt}"></td><td th:text="${member.leftAt}"></td><td th:text="${member.currentLeader} ? 'Leader' : 'Member'"></td></tr></tbody>
+  </table>
+  <form method="post" th:action="@{/projects/{id}/members(id=${project.id})}"><label for="intern">Intern user ID</label><input id="intern" name="internUserId" type="number" min="1" required><button type="submit">Add member</button></form>
+</main>
+</body>
+</html>
diff --git a/src/test/java/com/lab/labtimesheet/feature/project/controller/ProjectControllerTest.java b/src/test/java/com/lab/labtimesheet/feature/project/controller/ProjectControllerTest.java
new file mode 100644
index 0000000..ed3ef9f
--- /dev/null
+++ b/src/test/java/com/lab/labtimesheet/feature/project/controller/ProjectControllerTest.java
@@ -0,0 +1,142 @@
+package com.lab.labtimesheet.feature.project.controller;
+
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors.csrf;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.model;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.redirectedUrl;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.view;
+
+import com.lab.labtimesheet.feature.project.exception.ProjectAccessDeniedException;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectCreateCommand;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectDetail;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectSummary;
+import com.lab.labtimesheet.feature.project.service.ProjectQueryService;
+import com.lab.labtimesheet.feature.project.service.ProjectService;
+import java.time.LocalDate;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.webmvc.test.autoconfigure.WebMvcTest;
+import org.springframework.security.test.context.support.WithMockUser;
+import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.test.web.servlet.MockMvc;
+
+@WebMvcTest(ProjectController.class)
+class ProjectControllerTest {
+
+    @Autowired
+    private MockMvc mvc;
+
+    @MockitoBean
+    private ProjectQueryService pages;
+
+    @MockitoBean
+    private ProjectService projects;
+
+    @Test
+    @WithMockUser(username = "mentor@example.test")
+    void listsOnlyTheAuthenticatedUsersAuthorizedProjects() throws Exception {
+        when(pages.authenticatedUserId("mentor@example.test")).thenReturn(10L);
+        when(pages.listVisible(10L)).thenReturn(List.of(new ProjectSummary(
+                30L,
+                "Intern Portal Refresh",
+                "PLANNED",
+                LocalDate.of(2026, 8, 15),
+                LocalDate.of(2026, 9, 30))));
+
+        mvc.perform(get("/projects"))
+                .andExpect(status().isOk())
+                .andExpect(view().name("projects/list"))
+                .andExpect(model().attributeExists("projects"));
+
+        verify(pages).listVisible(10L);
+    }
+
+    @Test
+    @WithMockUser(username = "member@example.test")
+    void guessedProjectIdReturnsTheSameNotFoundResponseAsAMissingProject() throws Exception {
+        when(pages.authenticatedUserId("member@example.test")).thenReturn(20L);
+        when(pages.detail(20L, 999L)).thenThrow(new ProjectAccessDeniedException());
+
+        mvc.perform(get("/projects/999"))
+                .andExpect(status().isNotFound());
+    }
+
+    @Test
+    @WithMockUser(username = "member@example.test")
+    void memberAndLeadershipPagesUseTheSameProjectScopedAuthorization() throws Exception {
+        when(pages.authenticatedUserId("member@example.test")).thenReturn(20L);
+        when(pages.detail(20L, 30L)).thenReturn(new ProjectDetail(
+                30L,
+                "Intern Portal Refresh",
+                null,
+                "PLANNED",
+                LocalDate.of(2026, 8, 15),
+                LocalDate.of(2026, 9, 30),
+                "Mentor",
+                "Leader"));
+        when(pages.members(20L, 30L)).thenReturn(List.of());
+        when(pages.leadership(20L, 30L)).thenReturn(List.of());
+
+        mvc.perform(get("/projects/30/members"))
+                .andExpect(status().isOk())
+                .andExpect(view().name("projects/members"));
+        mvc.perform(get("/projects/30/leadership"))
+                .andExpect(status().isOk())
+                .andExpect(view().name("projects/leadership"));
+    }
+
+    @Test
+    @WithMockUser(username = "mentor@example.test")
+    void validCreateSubmissionUsesAuthenticatedMentorAndRedirectsToDetail() throws Exception {
+        when(pages.authenticatedUserId("mentor@example.test")).thenReturn(10L);
+        when(projects.create(
+                        10L,
+                        new ProjectCreateCommand(
+                                "Intern Portal Refresh",
+                                "Refresh portal",
+                                LocalDate.of(2026, 8, 15),
+                                LocalDate.of(2026, 9, 30),
+                                20L)))
+                .thenReturn(30L);
+
+        mvc.perform(post("/projects")
+                        .with(csrf())
+                        .param("name", "Intern Portal Refresh")
+                        .param("description", "Refresh portal")
+                        .param("startDate", "2026-08-15")
+                        .param("endDate", "2026-09-30")
+                        .param("initialLeaderUserId", "20"))
+                .andExpect(status().is3xxRedirection())
+                .andExpect(redirectedUrl("/projects/30"));
+    }
+
+    @Test
+    @WithMockUser(username = "mentor@example.test")
+    void invalidCreateSubmissionStaysOnSafeFormWithoutMutation() throws Exception {
+        mvc.perform(post("/projects")
+                        .with(csrf())
+                        .param("name", " ")
+                        .param("startDate", "2026-09-30")
+                        .param("endDate", "2026-08-15")
+                        .param("initialLeaderUserId", "0"))
+                .andExpect(status().isOk())
+                .andExpect(view().name("projects/form"))
+                .andExpect(model().attributeHasFieldErrors(
+                        "projectForm", "name", "initialLeaderUserId"));
+
+        verify(projects, never()).create(org.mockito.ArgumentMatchers.anyLong(), org.mockito.ArgumentMatchers.any());
+    }
+
+    @Test
+    @WithMockUser(username = "mentor@example.test")
+    void stateChangingRoutesRequireCsrf() throws Exception {
+        mvc.perform(post("/projects"))
+                .andExpect(status().isForbidden());
+    }
+}
diff --git a/src/test/java/com/lab/labtimesheet/projects/domain/ProjectTest.java b/src/test/java/com/lab/labtimesheet/feature/project/model/entity/ProjectEntityTest.java
similarity index 70%
rename from src/test/java/com/lab/labtimesheet/projects/domain/ProjectTest.java
rename to src/test/java/com/lab/labtimesheet/feature/project/model/entity/ProjectEntityTest.java
index 8583541..16f1a2d 100644
--- a/src/test/java/com/lab/labtimesheet/projects/domain/ProjectTest.java
+++ b/src/test/java/com/lab/labtimesheet/feature/project/model/entity/ProjectEntityTest.java
@@ -1,21 +1,25 @@
-package com.lab.labtimesheet.projects.domain;
+package com.lab.labtimesheet.feature.project.model.entity;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import com.lab.labtimesheet.feature.project.exception.ProjectAccessDeniedException;
+import com.lab.labtimesheet.feature.project.exception.ProjectRuleViolationException;
+import com.lab.labtimesheet.feature.project.model.ProjectInternEligibility;
+import com.lab.labtimesheet.feature.project.model.ProjectStatus;
 import java.time.Instant;
 import java.time.LocalDate;
 import org.junit.jupiter.api.Test;
 
-class ProjectTest {
+class ProjectEntityTest {
 
     private static final Instant CREATED_AT = Instant.parse("2026-08-14T02:00:00Z");
 
     @Test
     void planningCreatesTheInitialLeaderMembershipAndTermTogether() {
-        var project = Project.plan(
+        var project = ProjectEntity.plan(
                 10L,
                 " Intern Portal Refresh ",
                 " Refresh the portal ",
@@ -36,7 +40,7 @@ class ProjectTest {
 
     @Test
     void planningRejectsAnIneligibleInitialLeaderAndInvalidDates() {
-        assertThrows(ProjectRuleViolation.class, () -> Project.plan(
+        assertThrows(ProjectRuleViolationException.class, () -> ProjectEntity.plan(
                 10L,
                 "Project",
                 null,
@@ -44,13 +48,13 @@ class ProjectTest {
                 LocalDate.of(2026, 8, 31),
                 activeIntern(20L),
                 CREATED_AT));
-        assertThrows(ProjectRuleViolation.class, () -> Project.plan(
+        assertThrows(ProjectRuleViolationException.class, () -> ProjectEntity.plan(
                 10L,
                 "Project",
                 null,
                 LocalDate.of(2026, 8, 1),
                 LocalDate.of(2026, 8, 31),
-                new EligibleIntern(20L, false, true),
+                new ProjectInternEligibility(20L, false),
                 CREATED_AT));
     }
 
@@ -62,16 +66,16 @@ class ProjectTest {
 
         assertEquals(2, project.memberships().size());
         assertTrue(project.hasCurrentMember(21L));
-        assertThrows(ProjectRuleViolation.class,
+        assertThrows(ProjectRuleViolationException.class,
                 () -> project.addMember(10L, activeIntern(21L), CREATED_AT.plusSeconds(120)));
-        assertThrows(ProjectAccessDenied.class,
+        assertThrows(ProjectAccessDeniedException.class,
                 () -> project.addMember(11L, activeIntern(22L), CREATED_AT.plusSeconds(120)));
     }
 
     @Test
     void theSameInternCanBelongToSeparateProjects() {
         var first = plannedProject();
-        var second = Project.plan(
+        var second = ProjectEntity.plan(
                 11L,
                 "Second",
                 null,
@@ -91,38 +95,39 @@ class ProjectTest {
         var project = plannedProject();
         project.addMember(10L, activeIntern(21L), CREATED_AT.plusSeconds(60));
 
-        project.changeLeader(10L, activeIntern(21L), CREATED_AT.plusSeconds(120));
+        var change = project.prepareLeaderChange(10L, activeIntern(21L), CREATED_AT.plusSeconds(120));
+        project.completeLeaderChange(10L, change);
 
         assertEquals(2, project.memberships().size());
         assertEquals(2, project.leadershipTerms().size());
-        assertEquals(1, project.leadershipTerms().stream().filter(LeadershipTerm::isCurrent).count());
+        assertEquals(1, project.leadershipTerms().stream().filter(ProjectLeadershipTermEntity::isCurrent).count());
         assertEquals(21L, project.currentLeader().internUserId());
         assertFalse(project.leadershipTerms().getFirst().isCurrent());
-        assertThrows(ProjectRuleViolation.class,
-                () -> project.changeLeader(10L, activeIntern(21L), CREATED_AT.plusSeconds(180)));
-        assertThrows(ProjectRuleViolation.class,
-                () -> project.changeLeader(10L, activeIntern(22L), CREATED_AT.plusSeconds(180)));
+        assertThrows(ProjectRuleViolationException.class,
+                () -> project.prepareLeaderChange(10L, activeIntern(21L), CREATED_AT.plusSeconds(180)));
+        assertThrows(ProjectRuleViolationException.class,
+                () -> project.prepareLeaderChange(10L, activeIntern(22L), CREATED_AT.plusSeconds(180)));
     }
 
     @Test
     void activationRequiresOwnerAndValidCurrentTaskAssignees() {
         var project = plannedProject();
 
-        assertThrows(ProjectAccessDenied.class,
+        assertThrows(ProjectAccessDeniedException.class,
                 () -> project.activate(11L, true, CREATED_AT.plusSeconds(60)));
-        assertThrows(ProjectRuleViolation.class,
+        assertThrows(ProjectRuleViolationException.class,
                 () -> project.activate(10L, false, CREATED_AT.plusSeconds(60)));
 
         project.activate(10L, true, CREATED_AT.plusSeconds(60));
 
         assertEquals(ProjectStatus.ACTIVE, project.status());
         assertEquals(CREATED_AT.plusSeconds(60), project.activatedAt());
-        assertThrows(ProjectRuleViolation.class,
+        assertThrows(ProjectRuleViolationException.class,
                 () -> project.activate(10L, true, CREATED_AT.plusSeconds(120)));
     }
 
-    private static Project plannedProject() {
-        return Project.plan(
+    private static ProjectEntity plannedProject() {
+        return ProjectEntity.plan(
                 10L,
                 "Project",
                 null,
@@ -132,7 +137,7 @@ class ProjectTest {
                 CREATED_AT);
     }
 
-    private static EligibleIntern activeIntern(long userId) {
-        return new EligibleIntern(userId, true, true);
+    private static ProjectInternEligibility activeIntern(long userId) {
+        return new ProjectInternEligibility(userId, true);
     }
 }
diff --git a/src/test/java/com/lab/labtimesheet/feature/project/repository/ProjectPersistenceStructureTest.java b/src/test/java/com/lab/labtimesheet/feature/project/repository/ProjectPersistenceStructureTest.java
new file mode 100644
index 0000000..a3bab65
--- /dev/null
+++ b/src/test/java/com/lab/labtimesheet/feature/project/repository/ProjectPersistenceStructureTest.java
@@ -0,0 +1,31 @@
+package com.lab.labtimesheet.feature.project.repository;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.lab.labtimesheet.feature.project.model.entity.ProjectEntity;
+import com.lab.labtimesheet.feature.project.service.ProjectService;
+import java.util.Arrays;
+import org.junit.jupiter.api.Test;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.jdbc.core.JdbcOperations;
+
+class ProjectPersistenceStructureTest {
+
+    @Test
+    void projectPersistenceUsesTheRequiredLayerPackagesAndSpringDataJpa() {
+        assertTrue(ProjectEntity.class.getPackageName().startsWith("com.lab.labtimesheet.feature.project.model.entity"));
+        assertTrue(ProjectService.class.getPackageName().startsWith("com.lab.labtimesheet.feature.project.service"));
+        assertTrue(JpaRepository.class.isAssignableFrom(ProjectRepository.class));
+        assertTrue(ProjectRepository.class.getInterfaces().length > 0);
+        assertTrue(ProjectEntity.class.isAnnotationPresent(jakarta.persistence.Entity.class));
+        assertFalse(Arrays.stream(ProjectService.class.getDeclaredFields())
+                .map(field -> field.getType())
+                .anyMatch(JdbcOperations.class::isAssignableFrom));
+        assertThrows(ClassNotFoundException.class,
+                () -> Class.forName("com.lab.labtimesheet.feature.project.model.entity.ProjectUserEntity"));
+        assertThrows(ClassNotFoundException.class,
+                () -> Class.forName("com.lab.labtimesheet.feature.project.model.entity.ProjectTaskEntity"));
+    }
+}
diff --git a/src/test/java/com/lab/labtimesheet/feature/project/service/ProjectServiceIntegrationTest.java b/src/test/java/com/lab/labtimesheet/feature/project/service/ProjectServiceIntegrationTest.java
new file mode 100644
index 0000000..8db027a
--- /dev/null
+++ b/src/test/java/com/lab/labtimesheet/feature/project/service/ProjectServiceIntegrationTest.java
@@ -0,0 +1,231 @@
+package com.lab.labtimesheet.feature.project.service;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.lab.labtimesheet.config.TestcontainersConfiguration;
+import com.lab.labtimesheet.feature.project.exception.ProjectAccessDeniedException;
+import com.lab.labtimesheet.feature.project.exception.ProjectRuleViolationException;
+import com.lab.labtimesheet.feature.project.model.dto.ProjectCreateCommand;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
+import java.util.List;
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.PersistenceContext;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.annotation.Import;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.transaction.annotation.Transactional;
+
+@Import(TestcontainersConfiguration.class)
+@SpringBootTest
+@ActiveProfiles("test")
+@Transactional
+class ProjectServiceIntegrationTest {
+
+    private static final Instant NOW = Instant.parse("2026-08-14T00:00:00Z");
+
+    @Autowired
+    private ProjectService projectService;
+
+    @Autowired
+    private JdbcTemplate jdbc;
+
+    @Autowired
+    private ProjectQueryService projectPages;
+
+    @PersistenceContext
+    private EntityManager entityManager;
+
+    @Test
+    void createsProjectMembershipAndLeadershipInOneTransaction() {
+        long mentorId = user("mentor-create@example.test", "MENTOR");
+        long leaderId = intern("leader-create@example.test", "I001");
+
+        long projectId = projectService.create(
+                mentorId,
+                new ProjectCreateCommand(
+                        "Intern Portal Refresh",
+                        "Refresh the portal",
+                        LocalDate.of(2026, 8, 15),
+                        LocalDate.of(2026, 9, 30),
+                        leaderId));
+
+        assertEquals("PLANNED", text("select status from projects where id = ?", projectId));
+        assertEquals(1, count("select count(*) from project_memberships where project_id = ? and left_at is null", projectId));
+        assertEquals(1, count("select count(*) from project_leadership_terms where project_id = ? and ended_at is null", projectId));
+        assertEquals(leaderId, number("""
+                select membership.intern_user_id
+                from project_leadership_terms leadership
+                join project_memberships membership on membership.id = leadership.membership_id
+                where leadership.project_id = ? and leadership.ended_at is null
+                """, projectId));
+
+        long nonMentorId = intern("not-mentor@example.test", "I002");
+        assertThrows(ProjectAccessDeniedException.class, () -> projectService.create(
+                nonMentorId,
+                new ProjectCreateCommand(
+                        "Denied",
+                        null,
+                        LocalDate.of(2026, 8, 15),
+                        LocalDate.of(2026, 8, 31),
+                        leaderId)));
+        assertEquals(0, count("select count(*) from projects where name = 'Denied'"));
+    }
+
+    @Test
+    void ownerAddsEligibleMemberAndDuplicateCurrentMembershipIsRejected() {
+        long mentorId = user("mentor-add@example.test", "MENTOR");
+        long leaderId = intern("leader-add@example.test", "I003");
+        long memberId = intern("member-add@example.test", "I004");
+        long projectId = createProject(mentorId, leaderId, "Membership");
+        long otherProjectId = createProject(mentorId, memberId, "Concurrent membership");
+
+        projectService.addMember(mentorId, projectId, memberId);
+
+        assertEquals(1, count("""
+                select count(*) from project_memberships
+                where project_id = ? and intern_user_id = ? and left_at is null
+                """, projectId, memberId));
+        assertEquals(1, count("""
+                select count(*) from project_memberships
+                where project_id = ? and intern_user_id = ? and left_at is null
+                """, otherProjectId, memberId));
+        assertThrows(ProjectRuleViolationException.class,
+                () -> projectService.addMember(mentorId, projectId, memberId));
+        assertThrows(ProjectAccessDeniedException.class,
+                () -> projectService.addMember(
+                        user("other-mentor@example.test", "MENTOR"), projectId, Long.MAX_VALUE));
+    }
+
+    @Test
+    void leaderChangeClosesOneTermAndDoesNotMoveTaskAssignments() {
+        long mentorId = user("mentor-leader@example.test", "MENTOR");
+        long firstLeaderId = intern("leader-one@example.test", "I005");
+        long nextLeaderId = intern("leader-two@example.test", "I006");
+        long projectId = createProject(mentorId, firstLeaderId, "Leadership");
+        projectService.addMember(mentorId, projectId, nextLeaderId);
+        long firstMembershipId = membershipId(projectId, firstLeaderId);
+        jdbc.update("""
+                insert into tasks (
+                    project_id, assignee_membership_id, title,
+                    created_by_membership_id, assigned_by_membership_id)
+                values (?, ?, 'Keep assignee', ?, ?)
+                """, projectId, firstMembershipId, firstMembershipId, firstMembershipId);
+
+        projectService.changeLeader(mentorId, projectId, nextLeaderId);
+
+        assertEquals(1, count("select count(*) from project_leadership_terms where project_id = ? and ended_at is null", projectId));
+        assertEquals(1, count("select count(*) from project_leadership_terms where project_id = ? and ended_at is not null", projectId));
+        assertEquals(firstMembershipId, number("select assignee_membership_id from tasks where project_id = ?", projectId));
+    }
+
+    @Test
+    void listAndDetailQueriesEnforceRoleOwnershipAndMembershipWithoutIdDisclosure() {
+        long adminId = user("admin-view@example.test", "ADMIN");
+        long mentorId = user("mentor-view@example.test", "MENTOR");
+        long otherMentorId = user("other-mentor-view@example.test", "MENTOR");
+        long leaderId = intern("leader-view@example.test", "I009");
+        long memberId = intern("member-view@example.test", "I010");
+        long unrelatedId = intern("unrelated-view@example.test", "I011");
+        long projectId = createProject(mentorId, leaderId, "Visible project");
+        projectService.addMember(mentorId, projectId, memberId);
+
+        assertEquals(List.of(projectId), projectPages.listVisible(adminId).stream().map(summary -> summary.id()).toList());
+        assertEquals(List.of(projectId), projectPages.listVisible(mentorId).stream().map(summary -> summary.id()).toList());
+        assertEquals(List.of(), projectPages.listVisible(otherMentorId));
+        assertEquals(List.of(projectId), projectPages.listVisible(memberId).stream().map(summary -> summary.id()).toList());
+        assertEquals(List.of(), projectPages.listVisible(unrelatedId));
+        assertEquals(projectId, projectPages.detail(memberId, projectId).id());
+        assertEquals("INTERN", projectPages.authenticatedActor("member-view@example.test").role());
+        var taskContext = projectPages.taskContext(memberId, projectId);
+        assertEquals(mentorId, taskContext.mentorUserId());
+        assertEquals("PLANNED", taskContext.status());
+        assertEquals(2, taskContext.activeMembers().size());
+        assertEquals(membershipId(projectId, leaderId), taskContext.currentLeaderMembershipId());
+        jdbc.update("""
+                update projects set status = 'ACTIVE', activated_at = ?, updated_at = ? where id = ?
+                """, dbTime(NOW.plusSeconds(30)), dbTime(NOW.plusSeconds(30)), projectId);
+        entityManager.clear();
+        assertEquals(1, projectPages.dashboardSummary(adminId).activeProjectCount());
+        assertEquals(1, projectPages.dashboardSummary(mentorId).activeProjectCount());
+        assertEquals(2, projectPages.dashboardSummary(mentorId).distinctActiveMemberCount());
+        assertEquals(1, projectPages.dashboardSummary(memberId).activeProjectCount());
+        assertThrows(ProjectAccessDeniedException.class, () -> projectPages.detail(otherMentorId, projectId));
+        assertThrows(ProjectAccessDeniedException.class, () -> projectPages.detail(unrelatedId, projectId));
+        assertThrows(ProjectAccessDeniedException.class, () -> projectPages.detail(unrelatedId, Long.MAX_VALUE));
+
+        jdbc.update("""
+                update project_memberships
+                set left_at = ?, removed_by_mentor_user_id = ?
+                where project_id = ? and intern_user_id = ?
+                """, dbTime(NOW.plusSeconds(60)), mentorId, projectId, memberId);
+        entityManager.clear();
+
+        assertEquals(projectId, projectPages.detail(memberId, projectId).id());
+        assertTrue(projectPages.taskContext(memberId, projectId).activeMembers().stream()
+                .noneMatch(member -> member.userId() == memberId));
+        assertEquals(0, projectPages.dashboardSummary(memberId).activeProjectCount());
+        assertEquals(1, projectPages.dashboardSummary(mentorId).distinctActiveMemberCount());
+    }
+
+    private long createProject(long mentorId, long leaderId, String name) {
+        return projectService.create(
+                mentorId,
+                new ProjectCreateCommand(
+                        name,
+                        null,
+                        LocalDate.of(2026, 8, 15),
+                        LocalDate.of(2026, 9, 30),
+                        leaderId));
+    }
+
+    private long user(String email, String role) {
+        return jdbc.queryForObject("""
+                insert into app_users (
+                    email, display_name, password_hash, global_role, account_status, activated_at)
+                values (?, ?, '{noop}password-password', ?, 'ACTIVE', ?)
+                returning id
+                """, Long.class, email, email, role, dbTime(NOW));
+    }
+
+    private long intern(String email, String studentCode) {
+        long userId = user(email, "INTERN");
+        jdbc.update("""
+                insert into intern_profiles (
+                    user_id, student_code, internship_start_date, internship_end_date,
+                    internship_status, activated_at)
+                values (?, ?, date '2026-08-01', date '2026-12-31', 'ACTIVE', ?)
+                """, userId, studentCode, dbTime(NOW));
+        return userId;
+    }
+
+    private long membershipId(long projectId, long internUserId) {
+        return number("""
+                select id from project_memberships
+                where project_id = ? and intern_user_id = ? and left_at is null
+                """, projectId, internUserId);
+    }
+
+    private int count(String sql, Object... arguments) {
+        return jdbc.queryForObject(sql, Integer.class, arguments);
+    }
+
+    private long number(String sql, Object... arguments) {
+        return jdbc.queryForObject(sql, Long.class, arguments);
+    }
+
+    private String text(String sql, Object... arguments) {
+        return jdbc.queryForObject(sql, String.class, arguments);
+    }
+
+    private OffsetDateTime dbTime(Instant instant) {
+        return instant.atOffset(ZoneOffset.UTC);
+    }
+}