Add complete database schema and ORM models

Schema (002_tables.sql):
- users: accounts with nick, password hash, timestamps
- auth_tokens: per-device tokens with expiry, linked to users
- channels: chat rooms with topic and mode flags
- channel_members: membership with per-user modes (+o, +v)
- messages: channel/DM history with structured JSON meta
- message_queue: per-user pending delivery queue
- sessions: server-held session state with idle timeout
- server_links: federation peer configuration

Models (internal/models/):
- All models embed Base for database access
- Relation methods on models: User.Channels(), User.QueuedMessages(),
  Channel.Members(), Channel.RecentMessages(), ChannelMember.User(),
  ChannelMember.Channel(), AuthToken.User(), Session.User()
- IDs are UUIDs (TEXT), not auto-increment integers
- JSON tags use camelCase per lint rules

All tables verified: migrations apply cleanly, 0 lint issues.

internal/models/auth_token.go

@@ -0,0 +1,37 @@
+package models
+
+import (
+	"context"
+	"time"
+)
+
+// AuthToken represents an authentication token for a user session.
+type AuthToken struct {
+	Base
+
+	Token      string     `json:"-"`
+	UserID     string     `json:"userId"`
+	CreatedAt  time.Time  `json:"createdAt"`
+	ExpiresAt  *time.Time `json:"expiresAt,omitempty"`
+	LastUsedAt *time.Time `json:"lastUsedAt,omitempty"`
+}
+
+// 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
+	}
+
+	return u, nil
+}

internal/models/channel.go

@@ -1,6 +1,7 @@
 package models
 
 import (
+	"context"
 	"time"
 )
 
@@ -8,10 +9,88 @@ import (
 type Channel struct {
 	Base
 
-	ID        int64     `json:"id"`
+	ID        string    `json:"id"`
 	Name      string    `json:"name"`
 	Topic     string    `json:"topic"`
 	Modes     string    `json:"modes"`
 	CreatedAt time.Time `json:"createdAt"`
 	UpdatedAt time.Time `json:"updatedAt"`
 }
+
+// Members returns all users who are members of this channel.
+func (c *Channel) Members(ctx context.Context) ([]*ChannelMember, error) {
+	rows, err := c.GetDB().QueryContext(ctx, `
+		SELECT cm.channel_id, cm.user_id, cm.modes, cm.joined_at,
+		       u.nick
+		FROM channel_members cm
+		JOIN users u ON u.id = cm.user_id
+		WHERE cm.channel_id = ?
+		ORDER BY cm.joined_at`,
+		c.ID,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var members []*ChannelMember
+
+	for rows.Next() {
+		m := &ChannelMember{}
+		m.SetDB(c.db)
+
+		err = rows.Scan(
+			&m.ChannelID, &m.UserID, &m.Modes,
+			&m.JoinedAt, &m.Nick,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		members = append(members, m)
+	}
+
+	return members, rows.Err()
+}
+
+// RecentMessages returns the most recent messages in this channel.
+func (c *Channel) RecentMessages(
+	ctx context.Context,
+	limit int,
+) ([]*Message, error) {
+	rows, err := c.GetDB().QueryContext(ctx, `
+		SELECT id, ts, from_user_id, from_nick,
+		       target, type, body, meta, created_at
+		FROM messages
+		WHERE target = ?
+		ORDER BY ts DESC
+		LIMIT ?`,
+		c.Name, limit,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var messages []*Message
+
+	for rows.Next() {
+		msg := &Message{}
+		msg.SetDB(c.db)
+
+		err = rows.Scan(
+			&msg.ID, &msg.Timestamp, &msg.FromUserID,
+			&msg.FromNick, &msg.Target, &msg.Type,
+			&msg.Body, &msg.Meta, &msg.CreatedAt,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		messages = append(messages, msg)
+	}
+
+	return messages, rows.Err()
+}

internal/models/channel_member.go

@@ -0,0 +1,57 @@
+package models
+
+import (
+	"context"
+	"time"
+)
+
+// ChannelMember represents a user's membership in a channel.
+type ChannelMember struct {
+	Base
+
+	ChannelID string    `json:"channelId"`
+	UserID    string    `json:"userId"`
+	Modes     string    `json:"modes"`
+	JoinedAt  time.Time `json:"joinedAt"`
+	Nick      string    `json:"nick"` // denormalized from users table
+}
+
+// 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
+	}
+
+	return u, nil
+}
+
+// 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
+	}
+
+	return c, nil
+}

internal/models/message.go

@@ -0,0 +1,20 @@
+package models
+
+import (
+	"time"
+)
+
+// Message represents a chat message (channel or DM).
+type Message struct {
+	Base
+
+	ID         string    `json:"id"`
+	Timestamp  time.Time `json:"ts"`
+	FromUserID string    `json:"fromUserId"`
+	FromNick   string    `json:"from"`
+	Target     string    `json:"to"`
+	Type       string    `json:"type"`
+	Body       string    `json:"body"`
+	Meta       string    `json:"meta"`
+	CreatedAt  time.Time `json:"createdAt"`
+}

internal/models/message_queue.go

@@ -0,0 +1,15 @@
+package models
+
+import (
+	"time"
+)
+
+// MessageQueueEntry represents a pending message delivery for a user.
+type MessageQueueEntry struct {
+	Base
+
+	ID        int64     `json:"id"`
+	UserID    string    `json:"userId"`
+	MessageID string    `json:"messageId"`
+	QueuedAt  time.Time `json:"queuedAt"`
+}

internal/models/model.go

@@ -1,9 +1,11 @@
 // Package models defines the data models used by the chat application.
+// All model structs embed Base, which provides database access for
+// relation-fetching methods directly on model instances.
 package models
 
 import "database/sql"
 
-// DB is the interface that models use to query relations.
+// DB is the interface that models use to query the database.
 // This avoids a circular import with the db package.
 type DB interface {
 	GetDB() *sql.DB
@@ -18,3 +20,8 @@ type Base struct {
 func (b *Base) SetDB(d DB) {
 	b.db = d
 }
+
+// GetDB returns the database interface for use in model methods.
+func (b *Base) GetDB() *sql.DB {
+	return b.db.GetDB()
+}

internal/models/server_link.go

@@ -0,0 +1,18 @@
+package models
+
+import (
+	"time"
+)
+
+// ServerLink represents a federation peer server configuration.
+type ServerLink struct {
+	Base
+
+	ID            string     `json:"id"`
+	Name          string     `json:"name"`
+	URL           string     `json:"url"`
+	SharedKeyHash string     `json:"-"`
+	IsActive      bool       `json:"isActive"`
+	CreatedAt     time.Time  `json:"createdAt"`
+	LastSeenAt    *time.Time `json:"lastSeenAt,omitempty"`
+}

internal/models/session.go

@@ -0,0 +1,37 @@
+package models
+
+import (
+	"context"
+	"time"
+)
+
+// Session represents a server-held user session.
+type Session struct {
+	Base
+
+	ID           string     `json:"id"`
+	UserID       string     `json:"userId"`
+	CreatedAt    time.Time  `json:"createdAt"`
+	LastActiveAt time.Time  `json:"lastActiveAt"`
+	ExpiresAt    *time.Time `json:"expiresAt,omitempty"`
+}
+
+// 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
+	}
+
+	return u, nil
+}

internal/models/user.go

@@ -0,0 +1,92 @@
+package models
+
+import (
+	"context"
+	"time"
+)
+
+// User represents a registered user account.
+type User struct {
+	Base
+
+	ID           string     `json:"id"`
+	Nick         string     `json:"nick"`
+	PasswordHash string     `json:"-"`
+	CreatedAt    time.Time  `json:"createdAt"`
+	UpdatedAt    time.Time  `json:"updatedAt"`
+	LastSeenAt   *time.Time `json:"lastSeenAt,omitempty"`
+}
+
+// Channels returns all channels the user is a member of.
+func (u *User) Channels(ctx context.Context) ([]*Channel, error) {
+	rows, err := u.GetDB().QueryContext(ctx, `
+		SELECT c.id, c.name, c.topic, c.modes, c.created_at, c.updated_at
+		FROM channels c
+		JOIN channel_members cm ON cm.channel_id = c.id
+		WHERE cm.user_id = ?
+		ORDER BY c.name`,
+		u.ID,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var channels []*Channel
+
+	for rows.Next() {
+		c := &Channel{}
+		c.SetDB(u.db)
+
+		err = rows.Scan(
+			&c.ID, &c.Name, &c.Topic, &c.Modes,
+			&c.CreatedAt, &c.UpdatedAt,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		channels = append(channels, c)
+	}
+
+	return channels, rows.Err()
+}
+
+// QueuedMessages returns undelivered messages for this user.
+func (u *User) QueuedMessages(ctx context.Context) ([]*Message, error) {
+	rows, err := u.GetDB().QueryContext(ctx, `
+		SELECT m.id, m.ts, m.from_user_id, m.from_nick,
+		       m.target, m.type, m.body, m.meta, m.created_at
+		FROM messages m
+		JOIN message_queue mq ON mq.message_id = m.id
+		WHERE mq.user_id = ?
+		ORDER BY mq.queued_at ASC`,
+		u.ID,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var messages []*Message
+
+	for rows.Next() {
+		msg := &Message{}
+		msg.SetDB(u.db)
+
+		err = rows.Scan(
+			&msg.ID, &msg.Timestamp, &msg.FromUserID,
+			&msg.FromNick, &msg.Target, &msg.Type,
+			&msg.Body, &msg.Meta, &msg.CreatedAt,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		messages = append(messages, msg)
+	}
+
+	return messages, rows.Err()
+}