feat(achievement): add rank-up notifications (#165)

RE'd putDisplayed_achievement from ZZ client DLL via Ghidra: the packet
sends opcode + 1 zero byte with no achievement ID, acting as a blanket
"I saw everything" signal.

Server changes:
- Track per-character last-displayed levels in new displayed_levels
  column (migration 0008)
- GetAchievement compares current vs displayed levels per entry
- DisplayedAchievement snapshots current levels to clear notifications
- Repo, service, mock, and 3 new service tests

Protbot changes:
- New --action achievement: fetches achievements, shows rank-up markers,
  sends DISPLAYED_ACHIEVEMENT, re-fetches to verify notifications clear
- Packet builders for GET/ADD/DISPLAYED_ACHIEVEMENT

server/channelserver/handlers_achievement.go

@@ -114,7 +114,7 @@ func handleMsgMhfGetAchievement(s *Session, p mhfpacket.MHFPacket) {
 		resp.WriteUint8(ach.Level)
 		resp.WriteUint16(ach.NextValue)
 		resp.WriteUint32(ach.Required)
-		resp.WriteBool(false) // TODO: Notify on rank increase since last checked, see MhfDisplayedAchievement
+		resp.WriteBool(summary.Notify[id])
 		resp.WriteUint8(ach.Trophy)
 		/* Trophy bitfield
 		0000 0000
@@ -152,7 +152,9 @@ func handleMsgMhfAddAchievement(s *Session, p mhfpacket.MHFPacket) {
 func handleMsgMhfPaymentAchievement(s *Session, p mhfpacket.MHFPacket) {}
 
 func handleMsgMhfDisplayedAchievement(s *Session, p mhfpacket.MHFPacket) {
-	// This is how you would figure out if the rank-up notification needs to occur
+	if err := s.server.achievementService.MarkDisplayed(s.charID); err != nil {
+		s.logger.Warn("Failed to mark achievements as displayed", zap.Error(err))
+	}
 }
 
 func handleMsgMhfGetCaAchievementHist(s *Session, p mhfpacket.MHFPacket) {}

server/channelserver/repo_achievement.go

@@ -42,3 +42,18 @@ func (r *AchievementRepository) IncrementScore(charID uint32, achievementID uint
 	_, err := r.db.Exec(fmt.Sprintf("UPDATE achievements SET ach%d=ach%d+1 WHERE id=$1", achievementID, achievementID), charID)
 	return err
 }
+
+// GetDisplayedLevels returns the last-displayed achievement levels for a character.
+// Returns nil if never displayed (all rank-ups should trigger notifications).
+func (r *AchievementRepository) GetDisplayedLevels(charID uint32) ([]byte, error) {
+	var levels []byte
+	err := r.db.QueryRow("SELECT displayed_levels FROM achievements WHERE id=$1", charID).Scan(&levels)
+	return levels, err
+}
+
+// SaveDisplayedLevels stores the current achievement levels as "displayed",
+// so future GET_ACHIEVEMENT responses only notify on new rank-ups.
+func (r *AchievementRepository) SaveDisplayedLevels(charID uint32, levels []byte) error {
+	_, err := r.db.Exec("UPDATE achievements SET displayed_levels=$1 WHERE id=$2", levels, charID)
+	return err
+}

server/channelserver/repo_interfaces.go

@@ -290,6 +290,8 @@ type AchievementRepo interface {
 	EnsureExists(charID uint32) error
 	GetAllScores(charID uint32) ([33]int32, error)
 	IncrementScore(charID uint32, achievementID uint8) error
+	GetDisplayedLevels(charID uint32) ([]byte, error)
+	SaveDisplayedLevels(charID uint32, levels []byte) error
 }
 
 // ShopRepo defines the contract for shop data access.

server/channelserver/repo_mocks_test.go

@@ -11,12 +11,16 @@ var errNotFound = errors.New("not found")
 // --- mockAchievementRepo ---
 
 type mockAchievementRepo struct {
-	scores        [33]int32
-	ensureCalled  bool
-	ensureErr     error
-	getScoresErr  error
-	incrementErr  error
-	incrementedID uint8
+	scores          [33]int32
+	ensureCalled    bool
+	ensureErr       error
+	getScoresErr    error
+	incrementErr    error
+	incrementedID   uint8
+	displayedLevels []byte
+	displayedErr    error
+	savedLevels     []byte
+	saveLevelsErr   error
 }
 
 func (m *mockAchievementRepo) EnsureExists(_ uint32) error {
@@ -33,6 +37,15 @@ func (m *mockAchievementRepo) IncrementScore(_ uint32, id uint8) error {
 	return m.incrementErr
 }
 
+func (m *mockAchievementRepo) GetDisplayedLevels(_ uint32) ([]byte, error) {
+	return m.displayedLevels, m.displayedErr
+}
+
+func (m *mockAchievementRepo) SaveDisplayedLevels(_ uint32, levels []byte) error {
+	m.savedLevels = levels
+	return m.saveLevelsErr
+}
+
 // --- mockMailRepo ---
 
 type mockMailRepo struct {

server/channelserver/svc_achievement.go

@@ -23,6 +23,7 @@ const achievementEntryCount = uint8(33)
 type AchievementSummary struct {
 	Points       uint32
 	Achievements [33]Achievement
+	Notify       [33]bool
 }
 
 // GetAll ensures the achievement record exists, fetches all scores, and computes
@@ -38,15 +39,49 @@ func (svc *AchievementService) GetAll(charID uint32) (*AchievementSummary, error
 		return nil, err
 	}
 
+	displayed, err := svc.achievementRepo.GetDisplayedLevels(charID)
+	if err != nil {
+		svc.logger.Debug("No displayed levels found, all rank-ups will notify", zap.Error(err))
+	}
+
 	var summary AchievementSummary
 	for id := uint8(0); id < achievementEntryCount; id++ {
 		ach := GetAchData(id, scores[id])
 		summary.Points += ach.Value
 		summary.Achievements[id] = ach
+
+		// Notify if current level exceeds the last-displayed level.
+		if ach.Level > 0 {
+			if displayed == nil || int(id) >= len(displayed) {
+				summary.Notify[id] = true
+			} else if ach.Level > displayed[id] {
+				summary.Notify[id] = true
+			}
+		}
 	}
 	return &summary, nil
 }
 
+// MarkDisplayed snapshots the current achievement levels so that future
+// GET_ACHIEVEMENT responses only notify on new rank-ups since this point.
+func (svc *AchievementService) MarkDisplayed(charID uint32) error {
+	if err := svc.achievementRepo.EnsureExists(charID); err != nil {
+		svc.logger.Error("Failed to ensure achievements record", zap.Error(err))
+	}
+
+	scores, err := svc.achievementRepo.GetAllScores(charID)
+	if err != nil {
+		return err
+	}
+
+	levels := make([]byte, achievementEntryCount)
+	for id := uint8(0); id < achievementEntryCount; id++ {
+		ach := GetAchData(id, scores[id])
+		levels[id] = ach.Level
+	}
+	return svc.achievementRepo.SaveDisplayedLevels(charID, levels)
+}
+
 // Increment validates the achievement ID, ensures the record exists, and bumps
 // the score for the given achievement category.
 func (svc *AchievementService) Increment(charID uint32, achievementID uint8) error {

server/channelserver/svc_achievement_test.go

@@ -65,6 +65,86 @@ func TestAchievementService_GetAll(t *testing.T) {
 	}
 }
 
+func TestAchievementService_GetAll_NotifyOnNewRankUp(t *testing.T) {
+	// Scores: ach0=5 (level 1), ach1=0 (level 0), ach2=20 (level 2)
+	// Displayed: ach0 was level 0, ach1 was level 0, ach2 was level 2
+	// Expected: ach0 notifies (1 > 0), ach1 does not (level 0), ach2 does not (2 == 2)
+	mock := &mockAchievementRepo{
+		scores:          [33]int32{5, 0, 20},
+		displayedLevels: make([]byte, 33), // all zeros
+	}
+	mock.displayedLevels[2] = 2 // ach2 was already displayed at level 2
+
+	svc := newTestAchievementService(mock)
+	summary, err := svc.GetAll(1)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if !summary.Notify[0] {
+		t.Error("ach0: expected notify=true (level 1, displayed 0)")
+	}
+	if summary.Notify[1] {
+		t.Error("ach1: expected notify=false (level 0)")
+	}
+	if summary.Notify[2] {
+		t.Error("ach2: expected notify=false (level 2, displayed 2)")
+	}
+}
+
+func TestAchievementService_GetAll_NotifyAllWhenNeverDisplayed(t *testing.T) {
+	// No displayed levels (nil) — all achievements with level > 0 should notify.
+	mock := &mockAchievementRepo{
+		scores:       [33]int32{5, 15},
+		displayedErr: errNotFound,
+	}
+	svc := newTestAchievementService(mock)
+	summary, err := svc.GetAll(1)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if !summary.Notify[0] {
+		t.Error("ach0: expected notify=true (never displayed)")
+	}
+	if !summary.Notify[1] {
+		t.Error("ach1: expected notify=true (never displayed)")
+	}
+	if summary.Notify[2] {
+		t.Error("ach2: expected notify=false (level 0)")
+	}
+}
+
+func TestAchievementService_MarkDisplayed(t *testing.T) {
+	mock := &mockAchievementRepo{
+		scores: [33]int32{5, 0, 20}, // ach0=level1, ach1=level0, ach2=level2
+	}
+	svc := newTestAchievementService(mock)
+
+	err := svc.MarkDisplayed(1)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if !mock.ensureCalled {
+		t.Error("EnsureExists should have been called")
+	}
+	if mock.savedLevels == nil {
+		t.Fatal("SaveDisplayedLevels should have been called")
+	}
+	if len(mock.savedLevels) != 33 {
+		t.Fatalf("Expected 33 bytes, got %d", len(mock.savedLevels))
+	}
+	if mock.savedLevels[0] != 1 {
+		t.Errorf("ach0 level: got %d, want 1", mock.savedLevels[0])
+	}
+	if mock.savedLevels[1] != 0 {
+		t.Errorf("ach1 level: got %d, want 0", mock.savedLevels[1])
+	}
+	if mock.savedLevels[2] != 2 {
+		t.Errorf("ach2 level: got %d, want 2", mock.savedLevels[2])
+	}
+}
+
 func TestAchievementService_GetAll_EnsureErrorNonFatal(t *testing.T) {
 	mock := &mockAchievementRepo{
 		ensureErr: errNotFound,