Fix code review feedback items 1-6, 8-10

- Item 1: Extract GetUserByID/GetChannelByID lookup methods, use from relation methods
- Item 2: Initialize slices with literals so JSON gets [] not null
- Item 3: Populate CreatedAt/UpdatedAt with time.Now() on all Create methods
- Item 4: Wrap each migration's SQL + recording in a transaction
- Item 5: Check error from res.LastInsertId() in QueueMessage
- Item 6: Add DequeueMessages and AckMessages methods
- Item 8: Add GetUserByNick, GetUserByToken, DeleteAuthToken, UpdateUserLastSeen
- Item 9: Run PRAGMA foreign_keys = ON on every new connection
- Item 10: Builds clean, all tests pass

internal/models/auth_token.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"context"
+	"fmt"
 	"time"
 )
 
@@ -18,20 +19,9 @@ type AuthToken struct {
 
 // User returns the user who owns this token.
 func (t *AuthToken) User(ctx context.Context) (*User, error) {
-	u := &User{}
-	u.SetDB(t.db)
-
-	err := t.GetDB().QueryRowContext(ctx, `
-		SELECT id, nick, password_hash, created_at, updated_at, last_seen_at
-		FROM users WHERE id = ?`,
-		t.UserID,
-	).Scan(
-		&u.ID, &u.Nick, &u.PasswordHash,
-		&u.CreatedAt, &u.UpdatedAt, &u.LastSeenAt,
-	)
-	if err != nil {
-		return nil, err
+	if ul := t.GetUserLookup(); ul != nil {
+		return ul.GetUserByID(ctx, t.UserID)
 	}
 
-	return u, nil
+	return nil, fmt.Errorf("user lookup not available")
 }

internal/models/channel.go

@@ -34,7 +34,7 @@ func (c *Channel) Members(ctx context.Context) ([]*ChannelMember, error) {
 
 	defer func() { _ = rows.Close() }()
 
-	var members []*ChannelMember
+	members := []*ChannelMember{}
 
 	for rows.Next() {
 		m := &ChannelMember{}
@@ -74,7 +74,7 @@ func (c *Channel) RecentMessages(
 
 	defer func() { _ = rows.Close() }()
 
-	var messages []*Message
+	messages := []*Message{}
 
 	for rows.Next() {
 		msg := &Message{}

internal/models/channel_member.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"context"
+	"fmt"
 	"time"
 )
 
@@ -18,40 +19,18 @@ type ChannelMember struct {
 
 // User returns the full User for this membership.
 func (cm *ChannelMember) User(ctx context.Context) (*User, error) {
-	u := &User{}
-	u.SetDB(cm.db)
-
-	err := cm.GetDB().QueryRowContext(ctx, `
-		SELECT id, nick, password_hash, created_at, updated_at, last_seen_at
-		FROM users WHERE id = ?`,
-		cm.UserID,
-	).Scan(
-		&u.ID, &u.Nick, &u.PasswordHash,
-		&u.CreatedAt, &u.UpdatedAt, &u.LastSeenAt,
-	)
-	if err != nil {
-		return nil, err
+	if ul := cm.GetUserLookup(); ul != nil {
+		return ul.GetUserByID(ctx, cm.UserID)
 	}
 
-	return u, nil
+	return nil, fmt.Errorf("user lookup not available")
 }
 
 // Channel returns the full Channel for this membership.
 func (cm *ChannelMember) Channel(ctx context.Context) (*Channel, error) {
-	c := &Channel{}
-	c.SetDB(cm.db)
-
-	err := cm.GetDB().QueryRowContext(ctx, `
-		SELECT id, name, topic, modes, created_at, updated_at
-		FROM channels WHERE id = ?`,
-		cm.ChannelID,
-	).Scan(
-		&c.ID, &c.Name, &c.Topic, &c.Modes,
-		&c.CreatedAt, &c.UpdatedAt,
-	)
-	if err != nil {
-		return nil, err
+	if cl := cm.GetChannelLookup(); cl != nil {
+		return cl.GetChannelByID(ctx, cm.ChannelID)
 	}
 
-	return c, nil
+	return nil, fmt.Errorf("channel lookup not available")
 }

internal/models/model.go

@@ -3,7 +3,10 @@
 // relation-fetching methods directly on model instances.
 package models
 
-import "database/sql"
+import (
+	"context"
+	"database/sql"
+)
 
 // DB is the interface that models use to query the database.
 // This avoids a circular import with the db package.
@@ -11,6 +14,16 @@ type DB interface {
 	GetDB() *sql.DB
 }
 
+// UserLookup provides user lookup by ID without circular imports.
+type UserLookup interface {
+	GetUserByID(ctx context.Context, id string) (*User, error)
+}
+
+// ChannelLookup provides channel lookup by ID without circular imports.
+type ChannelLookup interface {
+	GetChannelByID(ctx context.Context, id string) (*Channel, error)
+}
+
 // Base is embedded in all model structs to provide database access.
 type Base struct {
 	db DB
@@ -25,3 +38,21 @@ func (b *Base) SetDB(d DB) {
 func (b *Base) GetDB() *sql.DB {
 	return b.db.GetDB()
 }
+
+// GetUserLookup returns the DB as a UserLookup if it implements the interface.
+func (b *Base) GetUserLookup() UserLookup {
+	if ul, ok := b.db.(UserLookup); ok {
+		return ul
+	}
+
+	return nil
+}
+
+// GetChannelLookup returns the DB as a ChannelLookup if it implements the interface.
+func (b *Base) GetChannelLookup() ChannelLookup {
+	if cl, ok := b.db.(ChannelLookup); ok {
+		return cl
+	}
+
+	return nil
+}

internal/models/session.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"context"
+	"fmt"
 	"time"
 )
 
@@ -18,20 +19,9 @@ type Session struct {
 
 // User returns the user who owns this session.
 func (s *Session) User(ctx context.Context) (*User, error) {
-	u := &User{}
-	u.SetDB(s.db)
-
-	err := s.GetDB().QueryRowContext(ctx, `
-		SELECT id, nick, password_hash, created_at, updated_at, last_seen_at
-		FROM users WHERE id = ?`,
-		s.UserID,
-	).Scan(
-		&u.ID, &u.Nick, &u.PasswordHash,
-		&u.CreatedAt, &u.UpdatedAt, &u.LastSeenAt,
-	)
-	if err != nil {
-		return nil, err
+	if ul := s.GetUserLookup(); ul != nil {
+		return ul.GetUserByID(ctx, s.UserID)
 	}
 
-	return u, nil
+	return nil, fmt.Errorf("user lookup not available")
 }

internal/models/user.go

@@ -33,7 +33,7 @@ func (u *User) Channels(ctx context.Context) ([]*Channel, error) {
 
 	defer func() { _ = rows.Close() }()
 
-	var channels []*Channel
+	channels := []*Channel{}
 
 	for rows.Next() {
 		c := &Channel{}
@@ -70,7 +70,7 @@ func (u *User) QueuedMessages(ctx context.Context) ([]*Message, error) {
 
 	defer func() { _ = rows.Close() }()
 
-	var messages []*Message
+	messages := []*Message{}
 
 	for rows.Next() {
 		msg := &Message{}