refactor(channelserver): standardize on BeginTxx for all repository transactions

Replace db.Begin() with db.BeginTxx(context.Background(), nil) across all
8 remaining call sites in repo_guild.go, repo_guild_rp.go, repo_festa.go,
and repo_event.go. Use deferred Rollback() instead of explicit rollback
at each error return, eliminating 15 manual rollback calls.

docs/technical-debt.md

@@ -114,19 +114,9 @@ The pattern `m.Field, _ = stringsupport.SJISToUTF8(...)` appears across:
 
 A malformed SJIS string from a client yields an empty string with no log output, making garbled text impossible to debug. The error return should at least be logged at debug level.
 
-### 6. Inconsistent transaction API
+### ~~6. Inconsistent transaction API~~ (Fixed)
 
-`repo_guild.go` mixes two transaction styles in the same file:
-
-```go
-// Line 175 — no context, old style
-tx, err := r.db.Begin()
-
-// Line 518 — sqlx-idiomatic, with context
-tx, err := r.db.BeginTxx(context.Background(), nil)
-```
-
-Should standardize on `BeginTxx` throughout. The `Begin()` calls cannot carry a context for cancellation or timeout.
+**Status:** Fixed. All transaction call sites now use `BeginTxx(context.Background(), nil)` with deferred rollback, replacing the old `Begin()` + manual rollback pattern across `repo_guild.go`, `repo_guild_rp.go`, `repo_festa.go`, and `repo_event.go`.
 
 ### ~~7. `LoopDelay` config has no Viper default~~ (Fixed)
 
@@ -162,4 +152,4 @@ Based on impact and the momentum from recent repo-interface refactoring:
 5. ~~**Fix `fmt.Sprintf` in logger calls**~~ — **Done**
 6. ~~**Add `LoopDelay` Viper default**~~ — **Done**
 7. **Log SJIS decoding errors** — improves debuggability for text issues
-8. **Standardize on `BeginTxx`** — consistency fix in `repo_guild.go`
+8. ~~**Standardize on `BeginTxx`**~~ — **Done**

server/channelserver/repo_event.go

@@ -1,6 +1,7 @@
 package channelserver
 
 import (
+	"context"
 	"time"
 
 	"github.com/jmoiron/sqlx"
@@ -79,13 +80,14 @@ func (r *EventRepository) UpdateEventQuestStartTimes(updates []EventQuestUpdate)
 	if len(updates) == 0 {
 		return nil
 	}
-	tx, err := r.db.Begin()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return err
 	}
+	defer func() { _ = tx.Rollback() }()
+
 	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
 		}
 	}

server/channelserver/repo_festa.go

@@ -1,6 +1,7 @@
 package channelserver
 
 import (
+	"context"
 	"database/sql"
 
 	"github.com/jmoiron/sqlx"
@@ -181,16 +182,17 @@ func (r *FestaRepository) RegisterGuild(guildID uint32, team string) error {
 
 // SubmitSouls records soul submissions for a character within a transaction.
 func (r *FestaRepository) SubmitSouls(charID, guildID uint32, souls []uint16) error {
-	tx, err := r.db.Begin()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return err
 	}
+	defer func() { _ = tx.Rollback() }()
+
 	for i, s := range souls {
 		if s == 0 {
 			continue
 		}
 		if _, err := tx.Exec(`INSERT INTO festa_submissions VALUES ($1, $2, $3, $4, now())`, charID, guildID, i, s); err != nil {
-			_ = tx.Rollback()
 			return err
 		}
 	}

server/channelserver/repo_guild.go

@@ -1,6 +1,7 @@
 package channelserver
 
 import (
+	"context"
 	"database/sql"
 	"errors"
 	"fmt"
@@ -168,10 +169,11 @@ func (r *GuildRepository) ListAll() ([]*Guild, error) {
 
 // Create creates a new guild and adds the leader as its first member.
 func (r *GuildRepository) Create(leaderCharID uint32, guildName string) (int32, error) {
-	tx, err := r.db.Begin()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return 0, err
 	}
+	defer func() { _ = tx.Rollback() }()
 
 	var guildID int32
 	err = tx.QueryRow(
@@ -179,13 +181,11 @@ func (r *GuildRepository) Create(leaderCharID uint32, guildName string) (int32,
 		guildName, leaderCharID,
 	).Scan(&guildID)
 	if err != nil {
-		_ = tx.Rollback()
 		return 0, err
 	}
 
 	_, err = tx.Exec(`INSERT INTO guild_characters (guild_id, character_id) VALUES ($1, $2)`, guildID, leaderCharID)
 	if err != nil {
-		_ = tx.Rollback()
 		return 0, err
 	}
 
@@ -207,10 +207,11 @@ func (r *GuildRepository) Save(guild *Guild) error {
 
 // Disband removes a guild, its members, and cleans up alliance references.
 func (r *GuildRepository) Disband(guildID uint32) error {
-	tx, err := r.db.Begin()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return err
 	}
+	defer func() { _ = tx.Rollback() }()
 
 	stmts := []string{
 		"DELETE FROM guild_characters WHERE guild_id = $1",
@@ -219,17 +220,14 @@ func (r *GuildRepository) Disband(guildID uint32) error {
 	}
 	for _, stmt := range stmts {
 		if _, err := tx.Exec(stmt, guildID); err != nil {
-			_ = tx.Rollback()
 			return err
 		}
 	}
 
 	if _, err := tx.Exec("UPDATE guild_alliances SET sub1_id=sub2_id, sub2_id=NULL WHERE sub1_id=$1", guildID); err != nil {
-		_ = tx.Rollback()
 		return err
 	}
 	if _, err := tx.Exec("UPDATE guild_alliances SET sub2_id=NULL WHERE sub2_id=$1", guildID); err != nil {
-		_ = tx.Rollback()
 		return err
 	}
 
@@ -244,13 +242,13 @@ func (r *GuildRepository) RemoveCharacter(charID uint32) error {
 
 // AcceptApplication deletes the application and adds the character to the guild.
 func (r *GuildRepository) AcceptApplication(guildID, charID uint32) error {
-	tx, err := r.db.Begin()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return err
 	}
+	defer func() { _ = tx.Rollback() }()
 
 	if _, err := tx.Exec(`DELETE FROM guild_applications WHERE character_id = $1`, charID); err != nil {
-		_ = tx.Rollback()
 		return err
 	}
 
@@ -258,7 +256,6 @@ func (r *GuildRepository) AcceptApplication(guildID, charID uint32) error {
 		INSERT INTO guild_characters (guild_id, character_id, order_index)
 		VALUES ($1, $2, (SELECT MAX(order_index) + 1 FROM guild_characters WHERE guild_id = $1))
 	`, guildID, charID); err != nil {
-		_ = tx.Rollback()
 		return err
 	}
 
@@ -275,18 +272,18 @@ func (r *GuildRepository) CreateApplication(guildID, charID, actorID uint32, app
 
 // 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()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return err
 	}
+	defer func() { _ = tx.Rollback() }()
+
 	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()
@@ -312,14 +309,14 @@ func (r *GuildRepository) RejectApplication(guildID, charID uint32) error {
 
 // ArrangeCharacters reorders guild members by updating their order_index values.
 func (r *GuildRepository) ArrangeCharacters(charIDs []uint32) error {
-	tx, err := r.db.Begin()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return err
 	}
+	defer func() { _ = tx.Rollback() }()
 
 	for i, id := range charIDs {
 		if _, err := tx.Exec("UPDATE guild_characters SET order_index = $1 WHERE character_id = $2", 2+i, id); err != nil {
-			_ = tx.Rollback()
 			return err
 		}
 	}

server/channelserver/repo_guild_rp.go

@@ -1,6 +1,9 @@
 package channelserver
 
-import "time"
+import (
+	"context"
+	"time"
+)
 
 // AddMemberDailyRP adds RP to a member's daily total.
 func (r *GuildRepository) AddMemberDailyRP(charID uint32, amount uint16) error {
@@ -56,36 +59,34 @@ func (r *GuildRepository) SetRoomExpiry(guildID uint32, expiry time.Time) error
 // then updates the guild's rp_reset_at timestamp.
 // Uses SELECT FOR UPDATE to prevent concurrent rollovers from racing.
 func (r *GuildRepository) RolloverDailyRP(guildID uint32, noon time.Time) error {
-	tx, err := r.db.Begin()
+	tx, err := r.db.BeginTxx(context.Background(), nil)
 	if err != nil {
 		return err
 	}
+	defer func() { _ = tx.Rollback() }()
+
 	// Lock the guild row and re-check whether rollover is still needed.
 	var rpResetAt time.Time
 	if err := tx.QueryRow(
 		`SELECT COALESCE(rp_reset_at, '2000-01-01'::timestamptz) FROM guilds WHERE id = $1 FOR UPDATE`,
 		guildID,
 	).Scan(&rpResetAt); err != nil {
-		_ = tx.Rollback()
 		return err
 	}
 	if !rpResetAt.Before(noon) {
 		// Another goroutine already rolled over; nothing to do.
-		_ = tx.Rollback()
 		return nil
 	}
 	if _, err := tx.Exec(
 		`UPDATE guild_characters SET rp_yesterday = rp_today, rp_today = 0 WHERE guild_id = $1`,
 		guildID,
 	); err != nil {
-		_ = tx.Rollback()
 		return err
 	}
 	if _, err := tx.Exec(
 		`UPDATE guilds SET rp_reset_at = $1 WHERE id = $2`,
 		noon, guildID,
 	); err != nil {
-		_ = tx.Rollback()
 		return err
 	}
 	return tx.Commit()