refactor(channelserver): eliminate *sql.Tx from repository interfaces

Hide transaction management inside repository implementations so
interfaces only expose domain types, enabling clean mocking and
decoupling handlers from PostgreSQL internals.

- Replace BeginTx + UpdateEventQuestStartTime with batch
  UpdateEventQuestStartTimes that manages its own transaction
- Remove tx parameter from CreateApplication, add composite
  CreateApplicationWithMail for atomic scout+mail operations
- Remove SendMailTx from MailRepo (sole caller migrated)
- Remove database/sql import from repo_interfaces.go

server/channelserver/handlers_guild_ops.go

@@ -60,7 +60,7 @@ func handleMsgMhfOperateGuild(s *Session, p mhfpacket.MHFPacket) {
 			_ = s.server.guildRepo.Save(guild)
 		}
 	case mhfpacket.OperateGuildApply:
-		err = s.server.guildRepo.CreateApplication(guild.ID, s.charID, s.charID, GuildApplicationTypeApplied, nil)
+		err = s.server.guildRepo.CreateApplication(guild.ID, s.charID, s.charID, GuildApplicationTypeApplied)
 		if err == nil {
 			bf.WriteUint32(guild.LeaderCharID)
 		} else {

server/channelserver/handlers_guild_scout.go

@@ -45,38 +45,14 @@ func handleMsgMhfPostGuildScout(s *Session, p mhfpacket.MHFPacket) {
 		return
 	}
 
-	transaction, err := s.server.db.Begin()
-
-	if err != nil {
-		s.logger.Error("Failed to begin transaction for guild scout", zap.Error(err))
-		doAckBufFail(s, pkt.AckHandle, nil)
-		return
-	}
-
-	err = s.server.guildRepo.CreateApplication(guildInfo.ID, pkt.CharID, s.charID, GuildApplicationTypeInvited, transaction)
-
-	if err != nil {
-		_ = transaction.Rollback()
-		s.logger.Error("Failed to create guild scout application", zap.Error(err))
-		doAckBufFail(s, pkt.AckHandle, nil)
-		return
-	}
-
-	err = s.server.mailRepo.SendMailTx(transaction, s.charID, pkt.CharID,
+	err = s.server.guildRepo.CreateApplicationWithMail(
+		guildInfo.ID, pkt.CharID, s.charID, GuildApplicationTypeInvited,
+		s.charID, pkt.CharID,
 		s.server.i18n.guild.invite.title,
-		fmt.Sprintf(s.server.i18n.guild.invite.body, guildInfo.Name),
-		0, 0, true, false)
+		fmt.Sprintf(s.server.i18n.guild.invite.body, guildInfo.Name))
 
 	if err != nil {
-		_ = transaction.Rollback()
-		doAckBufFail(s, pkt.AckHandle, nil)
-		return
-	}
-
-	err = transaction.Commit()
-
-	if err != nil {
-		s.logger.Error("Failed to commit guild scout transaction", zap.Error(err))
+		s.logger.Error("Failed to create guild scout application with mail", zap.Error(err))
 		doAckBufFail(s, pkt.AckHandle, nil)
 		return
 	}

server/channelserver/handlers_quest.go

@@ -342,12 +342,7 @@ func handleMsgMhfEnumerateQuest(s *Session, p mhfpacket.MHFPacket) {
 	quests, err := s.server.eventRepo.GetEventQuests()
 	if err == nil {
 		currentTime := time.Now()
-		tx, err := s.server.eventRepo.BeginTx()
-		if err != nil {
-			s.logger.Error("Failed to begin transaction for event quests", zap.Error(err))
-			doAckBufSucceed(s, pkt.AckHandle, bf.Data())
-			return
-		}
+		var updates []EventQuestUpdate
 
 		for i, eq := range quests {
 			// Use the Event Cycling system
@@ -364,11 +359,7 @@ func handleMsgMhfEnumerateQuest(s *Session, p mhfpacket.MHFPacket) {
 						// Normalize rotationTime to 12PM JST to align with the in-game events update notification.
 						newRotationTime := time.Date(rotationTime.Year(), rotationTime.Month(), rotationTime.Day(), 12, 0, 0, 0, TimeAdjusted().Location())
 
-						err = s.server.eventRepo.UpdateEventQuestStartTime(tx, eq.ID, newRotationTime)
-						if err != nil {
-							_ = tx.Rollback()
-							break
-						}
+						updates = append(updates, EventQuestUpdate{ID: eq.ID, StartTime: newRotationTime})
 						quests[i].StartTime = newRotationTime // Set the new start time so the quest can be used/removed immediately.
 						eq = quests[i]
 					}
@@ -399,7 +390,9 @@ func handleMsgMhfEnumerateQuest(s *Session, p mhfpacket.MHFPacket) {
 			}
 		}
 
-		_ = tx.Commit()
+		if err := s.server.eventRepo.UpdateEventQuestStartTimes(updates); err != nil {
+			s.logger.Error("Failed to update event quest start times", zap.Error(err))
+		}
 	}
 
 	tuneValues := []tuneValue{

server/channelserver/repo_event.go

@@ -1,7 +1,6 @@
 package channelserver
 
 import (
-	"database/sql"
 	"time"
 
 	"github.com/jmoiron/sqlx"
@@ -69,13 +68,26 @@ func (r *EventRepository) GetEventQuests() ([]EventQuest, error) {
 	return result, err
 }
 
-// UpdateEventQuestStartTime updates the start_time for an event quest within a transaction.
-func (r *EventRepository) UpdateEventQuestStartTime(tx *sql.Tx, id uint32, startTime time.Time) error {
-	_, err := tx.Exec("UPDATE event_quests SET start_time = $1 WHERE id = $2", startTime, id)
-	return err
+// EventQuestUpdate pairs a quest ID with its new start time.
+type EventQuestUpdate struct {
+	ID        uint32
+	StartTime time.Time
 }
 
-// BeginTx starts a new database transaction.
-func (r *EventRepository) BeginTx() (*sql.Tx, error) {
-	return r.db.Begin()
+// UpdateEventQuestStartTimes batch-updates start times within a single transaction.
+func (r *EventRepository) UpdateEventQuestStartTimes(updates []EventQuestUpdate) error {
+	if len(updates) == 0 {
+		return nil
+	}
+	tx, err := r.db.Begin()
+	if err != nil {
+		return err
+	}
+	for _, u := range updates {
+		if _, err := tx.Exec("UPDATE event_quests SET start_time = $1 WHERE id = $2", u.StartTime, u.ID); err != nil {
+			_ = tx.Rollback()
+			return err
+		}
+	}
+	return tx.Commit()
 }

server/channelserver/repo_event_test.go

@@ -96,65 +96,51 @@ func TestGetEventQuestsOrderByQuestID(t *testing.T) {
 	}
 }
 
-func TestBeginTxAndUpdateEventQuestStartTime(t *testing.T) {
+func TestUpdateEventQuestStartTimes(t *testing.T) {
 	repo, db := setupEventRepo(t)
 
 	originalTime := time.Date(2025, 1, 1, 12, 0, 0, 0, time.UTC)
-	questID := insertEventQuest(t, db, 1, 100, originalTime, 7, 3)
+	id1 := insertEventQuest(t, db, 1, 100, originalTime, 7, 3)
+	id2 := insertEventQuest(t, db, 2, 200, originalTime, 5, 2)
 
-	newTime := time.Date(2025, 6, 15, 12, 0, 0, 0, time.UTC)
+	newTime1 := time.Date(2025, 6, 15, 12, 0, 0, 0, time.UTC)
+	newTime2 := time.Date(2025, 7, 20, 12, 0, 0, 0, time.UTC)
 
-	tx, err := repo.BeginTx()
+	err := repo.UpdateEventQuestStartTimes([]EventQuestUpdate{
+		{ID: id1, StartTime: newTime1},
+		{ID: id2, StartTime: newTime2},
+	})
 	if err != nil {
-		t.Fatalf("BeginTx failed: %v", err)
+		t.Fatalf("UpdateEventQuestStartTimes failed: %v", err)
 	}
 
-	if err := repo.UpdateEventQuestStartTime(tx, questID, newTime); err != nil {
-		_ = tx.Rollback()
-		t.Fatalf("UpdateEventQuestStartTime failed: %v", err)
+	// Verify both updates
+	var got1, got2 time.Time
+	if err := db.QueryRow("SELECT start_time FROM event_quests WHERE id=$1", id1).Scan(&got1); err != nil {
+		t.Fatalf("Verification query failed for id1: %v", err)
 	}
-
-	if err := tx.Commit(); err != nil {
-		t.Fatalf("Commit failed: %v", err)
+	if !got1.Equal(newTime1) {
+		t.Errorf("Expected start_time %v for id1, got: %v", newTime1, got1)
 	}
-
-	// Verify the update
-	var got time.Time
-	if err := db.QueryRow("SELECT start_time FROM event_quests WHERE id=$1", questID).Scan(&got); err != nil {
-		t.Fatalf("Verification query failed: %v", err)
+	if err := db.QueryRow("SELECT start_time FROM event_quests WHERE id=$1", id2).Scan(&got2); err != nil {
+		t.Fatalf("Verification query failed for id2: %v", err)
 	}
-	if !got.Equal(newTime) {
-		t.Errorf("Expected start_time %v, got: %v", newTime, got)
+	if !got2.Equal(newTime2) {
+		t.Errorf("Expected start_time %v for id2, got: %v", newTime2, got2)
 	}
 }
 
-func TestUpdateEventQuestStartTimeRollback(t *testing.T) {
-	repo, db := setupEventRepo(t)
+func TestUpdateEventQuestStartTimesEmpty(t *testing.T) {
+	repo, _ := setupEventRepo(t)
 
-	originalTime := time.Date(2025, 1, 1, 12, 0, 0, 0, time.UTC)
-	questID := insertEventQuest(t, db, 1, 100, originalTime, 0, 0)
-
-	tx, err := repo.BeginTx()
+	// Empty slice should be a no-op
+	err := repo.UpdateEventQuestStartTimes(nil)
 	if err != nil {
-		t.Fatalf("BeginTx failed: %v", err)
+		t.Fatalf("UpdateEventQuestStartTimes with nil should not error, got: %v", err)
 	}
 
-	newTime := time.Date(2025, 6, 15, 12, 0, 0, 0, time.UTC)
-	if err := repo.UpdateEventQuestStartTime(tx, questID, newTime); err != nil {
-		t.Fatalf("UpdateEventQuestStartTime failed: %v", err)
-	}
-
-	// Rollback instead of commit
-	if err := tx.Rollback(); err != nil {
-		t.Fatalf("Rollback failed: %v", err)
-	}
-
-	// Verify original time is preserved
-	var got time.Time
-	if err := db.QueryRow("SELECT start_time FROM event_quests WHERE id=$1", questID).Scan(&got); err != nil {
-		t.Fatalf("Verification query failed: %v", err)
-	}
-	if !got.Equal(originalTime) {
-		t.Errorf("Expected original start_time %v after rollback, got: %v", originalTime, got)
+	err = repo.UpdateEventQuestStartTimes([]EventQuestUpdate{})
+	if err != nil {
+		t.Fatalf("UpdateEventQuestStartTimes with empty slice should not error, got: %v", err)
 	}
 }

server/channelserver/repo_guild.go

@@ -270,15 +270,30 @@ func (r *GuildRepository) AcceptApplication(guildID, charID uint32) error {
 }
 
 // CreateApplication inserts a guild application or invitation.
-// If tx is non-nil, the operation participates in the given transaction.
-func (r *GuildRepository) CreateApplication(guildID, charID, actorID uint32, appType GuildApplicationType, tx *sql.Tx) error {
-	query := `INSERT INTO guild_applications (guild_id, character_id, actor_id, application_type) VALUES ($1, $2, $3, $4)`
-	if tx != nil {
-		_, err := tx.Exec(query, guildID, charID, actorID, appType)
+func (r *GuildRepository) CreateApplication(guildID, charID, actorID uint32, appType GuildApplicationType) error {
+	_, err := r.db.Exec(
+		`INSERT INTO guild_applications (guild_id, character_id, actor_id, application_type) VALUES ($1, $2, $3, $4)`,
+		guildID, charID, actorID, appType)
+	return err
+}
+
+// CreateApplicationWithMail atomically creates an application and sends a notification mail.
+func (r *GuildRepository) CreateApplicationWithMail(guildID, charID, actorID uint32, appType GuildApplicationType, mailSenderID, mailRecipientID uint32, mailSubject, mailBody string) error {
+	tx, err := r.db.Begin()
+	if err != nil {
 		return err
 	}
-	_, err := r.db.Exec(query, guildID, charID, actorID, appType)
-	return err
+	if _, err := tx.Exec(
+		`INSERT INTO guild_applications (guild_id, character_id, actor_id, application_type) VALUES ($1, $2, $3, $4)`,
+		guildID, charID, actorID, appType); err != nil {
+		_ = tx.Rollback()
+		return err
+	}
+	if _, err := tx.Exec(mailInsertQuery, mailSenderID, mailRecipientID, mailSubject, mailBody, 0, 0, true, false); err != nil {
+		_ = tx.Rollback()
+		return err
+	}
+	return tx.Commit()
 }
 
 // CancelInvitation removes an invitation for a character.

server/channelserver/repo_guild_test.go

@@ -270,7 +270,7 @@ func TestApplicationWorkflow(t *testing.T) {
 	applicantID := CreateTestCharacter(t, db, user2, "Applicant")
 
 	// Create application
-	err := repo.CreateApplication(guildID, applicantID, applicantID, GuildApplicationTypeApplied, nil)
+	err := repo.CreateApplication(guildID, applicantID, applicantID, GuildApplicationTypeApplied)
 	if err != nil {
 		t.Fatalf("CreateApplication failed: %v", err)
 	}
@@ -324,7 +324,7 @@ func TestRejectApplication(t *testing.T) {
 	user2 := CreateTestUser(t, db, "reject_user")
 	applicantID := CreateTestCharacter(t, db, user2, "Rejected")
 
-	err := repo.CreateApplication(guildID, applicantID, applicantID, GuildApplicationTypeApplied, nil)
+	err := repo.CreateApplication(guildID, applicantID, applicantID, GuildApplicationTypeApplied)
 	if err != nil {
 		t.Fatalf("CreateApplication failed: %v", err)
 	}
@@ -539,7 +539,7 @@ func TestCancelInvitation(t *testing.T) {
 	user2 := CreateTestUser(t, db, "invite_user")
 	char2 := CreateTestCharacter(t, db, user2, "Invited")
 
-	if err := repo.CreateApplication(guildID, char2, leaderID, GuildApplicationTypeInvited, nil); err != nil {
+	if err := repo.CreateApplication(guildID, char2, leaderID, GuildApplicationTypeInvited); err != nil {
 		t.Fatalf("CreateApplication (invited) failed: %v", err)
 	}
 
@@ -562,7 +562,7 @@ func TestListInvitedCharacters(t *testing.T) {
 	user2 := CreateTestUser(t, db, "scout_user")
 	char2 := CreateTestCharacter(t, db, user2, "Scouted")
 
-	if err := repo.CreateApplication(guildID, char2, leaderID, GuildApplicationTypeInvited, nil); err != nil {
+	if err := repo.CreateApplication(guildID, char2, leaderID, GuildApplicationTypeInvited); err != nil {
 		t.Fatalf("CreateApplication failed: %v", err)
 	}
 
@@ -602,7 +602,7 @@ func TestGetByCharIDWithApplication(t *testing.T) {
 	user2 := CreateTestUser(t, db, "app_char_user")
 	char2 := CreateTestCharacter(t, db, user2, "Applicant2")
 
-	if err := repo.CreateApplication(guildID, char2, char2, GuildApplicationTypeApplied, nil); err != nil {
+	if err := repo.CreateApplication(guildID, char2, char2, GuildApplicationTypeApplied); err != nil {
 		t.Fatalf("CreateApplication failed: %v", err)
 	}
 
@@ -624,7 +624,7 @@ func TestGetMembersApplicants(t *testing.T) {
 	user2 := CreateTestUser(t, db, "applicant_member_user")
 	char2 := CreateTestCharacter(t, db, user2, "AppMember")
 
-	if err := repo.CreateApplication(guildID, char2, char2, GuildApplicationTypeApplied, nil); err != nil {
+	if err := repo.CreateApplication(guildID, char2, char2, GuildApplicationTypeApplied); err != nil {
 		t.Fatalf("CreateApplication failed: %v", err)
 	}
 
@@ -1485,3 +1485,39 @@ func TestDisbandCleansUpAlliance(t *testing.T) {
 		t.Errorf("Expected alliance to be deleted after parent guild disband, got: %+v", alliance)
 	}
 }
+
+// --- CreateApplicationWithMail ---
+
+func TestCreateApplicationWithMail(t *testing.T) {
+	repo, db, guildID, leaderID := setupGuildRepo(t)
+
+	user2 := CreateTestUser(t, db, "scout_mail_user")
+	char2 := CreateTestCharacter(t, db, user2, "ScoutTarget")
+
+	err := repo.CreateApplicationWithMail(
+		guildID, char2, leaderID, GuildApplicationTypeInvited,
+		leaderID, char2, "Guild Invite", "You have been invited!")
+	if err != nil {
+		t.Fatalf("CreateApplicationWithMail failed: %v", err)
+	}
+
+	// Verify application was created
+	has, err := repo.HasApplication(guildID, char2)
+	if err != nil {
+		t.Fatalf("HasApplication failed: %v", err)
+	}
+	if !has {
+		t.Error("Expected application to exist after CreateApplicationWithMail")
+	}
+
+	// Verify mail was sent
+	var mailCount int
+	if err := db.QueryRow(
+		"SELECT COUNT(*) FROM mail WHERE sender_id=$1 AND recipient_id=$2 AND subject=$3",
+		leaderID, char2, "Guild Invite").Scan(&mailCount); err != nil {
+		t.Fatalf("Mail verification query failed: %v", err)
+	}
+	if mailCount != 1 {
+		t.Errorf("Expected 1 mail row, got %d", mailCount)
+	}
+}

server/channelserver/repo_interfaces.go

@@ -1,7 +1,6 @@
 package channelserver
 
 import (
-	"database/sql"
 	"time"
 )
 
@@ -52,7 +51,8 @@ type GuildRepo interface {
 	Disband(guildID uint32) error
 	RemoveCharacter(charID uint32) error
 	AcceptApplication(guildID, charID uint32) error
-	CreateApplication(guildID, charID, actorID uint32, appType GuildApplicationType, tx *sql.Tx) error
+	CreateApplication(guildID, charID, actorID uint32, appType GuildApplicationType) error
+	CreateApplicationWithMail(guildID, charID, actorID uint32, appType GuildApplicationType, mailSenderID, mailRecipientID uint32, mailSubject, mailBody string) error
 	CancelInvitation(guildID, charID uint32) error
 	RejectApplication(guildID, charID uint32) error
 	ArrangeCharacters(charIDs []uint32) error
@@ -228,7 +228,6 @@ type RengokuRepo interface {
 // MailRepo defines the contract for in-game mail data access.
 type MailRepo interface {
 	SendMail(senderID, recipientID uint32, subject, body string, itemID, itemAmount uint16, isGuildInvite, isSystemMessage bool) error
-	SendMailTx(tx *sql.Tx, senderID, recipientID uint32, subject, body string, itemID, itemAmount uint16, isGuildInvite, isSystemMessage bool) error
 	GetListForCharacter(charID uint32) ([]Mail, error)
 	GetByID(id int) (*Mail, error)
 	MarkRead(id int) error
@@ -272,8 +271,7 @@ type EventRepo interface {
 	InsertLoginBoost(charID uint32, weekReq uint8, expiration, reset time.Time) error
 	UpdateLoginBoost(charID uint32, weekReq uint8, expiration, reset time.Time) error
 	GetEventQuests() ([]EventQuest, error)
-	UpdateEventQuestStartTime(tx *sql.Tx, id uint32, startTime time.Time) error
-	BeginTx() (*sql.Tx, error)
+	UpdateEventQuestStartTimes(updates []EventQuestUpdate) error
 }
 
 // AchievementRepo defines the contract for achievement data access.

server/channelserver/repo_mail.go

@@ -1,8 +1,6 @@
 package channelserver
 
 import (
-	"database/sql"
-
 	"github.com/jmoiron/sqlx"
 )
 
@@ -27,12 +25,6 @@ func (r *MailRepository) SendMail(senderID, recipientID uint32, subject, body st
 	return err
 }
 
-// SendMailTx inserts a new mail row within an existing transaction.
-func (r *MailRepository) SendMailTx(tx *sql.Tx, senderID, recipientID uint32, subject, body string, itemID, itemAmount uint16, isGuildInvite, isSystemMessage bool) error {
-	_, err := tx.Exec(mailInsertQuery, senderID, recipientID, subject, body, itemID, itemAmount, isGuildInvite, isSystemMessage)
-	return err
-}
-
 // GetListForCharacter loads all non-deleted mail for a character (max 32).
 func (r *MailRepository) GetListForCharacter(charID uint32) ([]Mail, error) {
 	rows, err := r.db.Queryx(`

server/channelserver/repo_mocks_test.go

@@ -1,7 +1,6 @@
 package channelserver
 
 import (
-	"database/sql"
 	"errors"
 	"time"
 )
@@ -102,10 +101,6 @@ func (m *mockMailRepo) SendMail(senderID, recipientID uint32, subject, body stri
 	return m.sendErr
 }
 
-func (m *mockMailRepo) SendMailTx(_ *sql.Tx, senderID, recipientID uint32, subject, body string, itemID, itemAmount uint16, isGuildInvite, isSystemMessage bool) error {
-	return m.SendMail(senderID, recipientID, subject, body, itemID, itemAmount, isGuildInvite, isSystemMessage)
-}
-
 // --- mockCharacterRepo ---
 
 type mockCharacterRepo struct {
@@ -271,7 +266,10 @@ func (m *mockGuildRepoForMail) Save(_ *Guild) error                    { return
 func (m *mockGuildRepoForMail) Disband(_ uint32) error                 { return nil }
 func (m *mockGuildRepoForMail) RemoveCharacter(_ uint32) error         { return nil }
 func (m *mockGuildRepoForMail) AcceptApplication(_, _ uint32) error    { return nil }
-func (m *mockGuildRepoForMail) CreateApplication(_, _, _ uint32, _ GuildApplicationType, _ *sql.Tx) error {
+func (m *mockGuildRepoForMail) CreateApplication(_, _, _ uint32, _ GuildApplicationType) error {
+	return nil
+}
+func (m *mockGuildRepoForMail) CreateApplicationWithMail(_, _, _ uint32, _ GuildApplicationType, _, _ uint32, _, _ string) error {
 	return nil
 }
 func (m *mockGuildRepoForMail) CancelInvitation(_, _ uint32) error              { return nil }