feat: MVP two-user chat via embedded SPA (#9)

Backend:
- Session/client UUID model: sessions table (uuid, nick, signing_key),
  clients table (uuid, session_id, token) with per-client message queues
- MOTD delivery as IRC numeric messages (375/372/376) on connect
- EnqueueToSession fans out to all clients of a session
- EnqueueToClient for targeted delivery (MOTD)
- All queries updated for session/client model

SPA client:
- Long-poll loop (15s timeout) instead of setInterval
- IRC message envelope parsing (command/from/to/body)
- Display JOIN/PART/NICK/TOPIC/QUIT system messages
- Nick change via /nick command
- Topic display in header bar
- Unread count badges on inactive tabs
- Auto-rejoin channels on reconnect (localStorage)
- Connection status indicator
- Message deduplication by UUID
- Channel history loaded on join
- /topic command support

Closes #9

internal/db/queries.go

@@ -55,76 +55,132 @@ type MemberInfo struct {
 	LastSeen time.Time `json:"lastSeen"`
 }
 
-// CreateUser registers a new user with the given nick.
-func (database *Database) CreateUser(
+// CreateSession registers a new session and its first client.
+func (database *Database) CreateSession(
 	ctx context.Context,
 	nick string,
-) (int64, string, error) {
+) (int64, int64, string, error) {
+	sessionUUID := uuid.New().String()
+	clientUUID := uuid.New().String()
+
 	token, err := generateToken()
 	if err != nil {
-		return 0, "", err
+		return 0, 0, "", err
 	}
 
 	now := time.Now()
 
-	res, err := database.conn.ExecContext(ctx,
-		`INSERT INTO users
-		 (nick, token, created_at, last_seen)
-		 VALUES (?, ?, ?, ?)`,
-		nick, token, now, now)
+	transaction, err := database.conn.BeginTx(ctx, nil)
 	if err != nil {
-		return 0, "", fmt.Errorf("create user: %w", err)
+		return 0, 0, "", fmt.Errorf(
+			"begin tx: %w", err,
+		)
 	}
 
-	userID, _ := res.LastInsertId()
+	res, err := transaction.ExecContext(ctx,
+		`INSERT INTO sessions
+		 (uuid, nick, created_at, last_seen)
+		 VALUES (?, ?, ?, ?)`,
+		sessionUUID, nick, now, now)
+	if err != nil {
+		_ = transaction.Rollback()
 
-	return userID, token, nil
+		return 0, 0, "", fmt.Errorf(
+			"create session: %w", err,
+		)
+	}
+
+	sessionID, _ := res.LastInsertId()
+
+	clientRes, err := transaction.ExecContext(ctx,
+		`INSERT INTO clients
+		 (uuid, session_id, token,
+		  created_at, last_seen)
+		 VALUES (?, ?, ?, ?, ?)`,
+		clientUUID, sessionID, token, now, now)
+	if err != nil {
+		_ = transaction.Rollback()
+
+		return 0, 0, "", fmt.Errorf(
+			"create client: %w", err,
+		)
+	}
+
+	clientID, _ := clientRes.LastInsertId()
+
+	err = transaction.Commit()
+	if err != nil {
+		return 0, 0, "", fmt.Errorf(
+			"commit session: %w", err,
+		)
+	}
+
+	return sessionID, clientID, token, nil
 }
 
-// GetUserByToken returns user id and nick for a token.
-func (database *Database) GetUserByToken(
+// GetSessionByToken returns session id, client id, and
+// nick for a client token.
+func (database *Database) GetSessionByToken(
 	ctx context.Context,
 	token string,
-) (int64, string, error) {
-	var userID int64
-
-	var nick string
+) (int64, int64, string, error) {
+	var (
+		sessionID int64
+		clientID  int64
+		nick      string
+	)
 
 	err := database.conn.QueryRowContext(
 		ctx,
-		"SELECT id, nick FROM users WHERE token = ?",
+		`SELECT s.id, c.id, s.nick
+		 FROM clients c
+		 INNER JOIN sessions s
+		   ON s.id = c.session_id
+		 WHERE c.token = ?`,
 		token,
-	).Scan(&userID, &nick)
+	).Scan(&sessionID, &clientID, &nick)
 	if err != nil {
-		return 0, "", fmt.Errorf("get user by token: %w", err)
+		return 0, 0, "", fmt.Errorf(
+			"get session by token: %w", err,
+		)
 	}
 
+	now := time.Now()
+
 	_, _ = database.conn.ExecContext(
 		ctx,
-		"UPDATE users SET last_seen = ? WHERE id = ?",
-		time.Now(), userID,
+		"UPDATE sessions SET last_seen = ? WHERE id = ?",
+		now, sessionID,
 	)
 
-	return userID, nick, nil
+	_, _ = database.conn.ExecContext(
+		ctx,
+		"UPDATE clients SET last_seen = ? WHERE id = ?",
+		now, clientID,
+	)
+
+	return sessionID, clientID, nick, nil
 }
 
-// GetUserByNick returns user id for a given nick.
-func (database *Database) GetUserByNick(
+// GetSessionByNick returns session id for a given nick.
+func (database *Database) GetSessionByNick(
 	ctx context.Context,
 	nick string,
 ) (int64, error) {
-	var userID int64
+	var sessionID int64
 
 	err := database.conn.QueryRowContext(
 		ctx,
-		"SELECT id FROM users WHERE nick = ?",
+		"SELECT id FROM sessions WHERE nick = ?",
 		nick,
-	).Scan(&userID)
+	).Scan(&sessionID)
 	if err != nil {
-		return 0, fmt.Errorf("get user by nick: %w", err)
+		return 0, fmt.Errorf(
+			"get session by nick: %w", err,
+		)
 	}
 
-	return userID, nil
+	return sessionID, nil
 }
 
 // GetChannelByName returns the channel ID for a name.
@@ -179,16 +235,16 @@ func (database *Database) GetOrCreateChannel(
 	return channelID, nil
 }
 
-// JoinChannel adds a user to a channel.
+// JoinChannel adds a session to a channel.
 func (database *Database) JoinChannel(
 	ctx context.Context,
-	channelID, userID int64,
+	channelID, sessionID int64,
 ) error {
 	_, err := database.conn.ExecContext(ctx,
 		`INSERT OR IGNORE INTO channel_members
-		 (channel_id, user_id, joined_at)
+		 (channel_id, session_id, joined_at)
 		 VALUES (?, ?, ?)`,
-		channelID, userID, time.Now())
+		channelID, sessionID, time.Now())
 	if err != nil {
 		return fmt.Errorf("join channel: %w", err)
 	}
@@ -196,15 +252,15 @@ func (database *Database) JoinChannel(
 	return nil
 }
 
-// PartChannel removes a user from a channel.
+// PartChannel removes a session from a channel.
 func (database *Database) PartChannel(
 	ctx context.Context,
-	channelID, userID int64,
+	channelID, sessionID int64,
 ) error {
 	_, err := database.conn.ExecContext(ctx,
 		`DELETE FROM channel_members
-		 WHERE channel_id = ? AND user_id = ?`,
-		channelID, userID)
+		 WHERE channel_id = ? AND session_id = ?`,
+		channelID, sessionID)
 	if err != nil {
 		return fmt.Errorf("part channel: %w", err)
 	}
@@ -265,18 +321,18 @@ func scanChannels(
 	return out, nil
 }
 
-// ListChannels returns channels the user has joined.
+// ListChannels returns channels the session has joined.
 func (database *Database) ListChannels(
 	ctx context.Context,
-	userID int64,
+	sessionID int64,
 ) ([]ChannelInfo, error) {
 	rows, err := database.conn.QueryContext(ctx,
 		`SELECT c.id, c.name, c.topic
 		 FROM channels c
 		 INNER JOIN channel_members cm
 		   ON cm.channel_id = c.id
-		 WHERE cm.user_id = ?
-		 ORDER BY c.name`, userID)
+		 WHERE cm.session_id = ?
+		 ORDER BY c.name`, sessionID)
 	if err != nil {
 		return nil, fmt.Errorf("list channels: %w", err)
 	}
@@ -306,12 +362,12 @@ func (database *Database) ChannelMembers(
 	channelID int64,
 ) ([]MemberInfo, error) {
 	rows, err := database.conn.QueryContext(ctx,
-		`SELECT u.id, u.nick, u.last_seen
-		 FROM users u
+		`SELECT s.id, s.nick, s.last_seen
+		 FROM sessions s
 		 INNER JOIN channel_members cm
-		   ON cm.user_id = u.id
+		   ON cm.session_id = s.id
 		 WHERE cm.channel_id = ?
-		 ORDER BY u.nick`, channelID)
+		 ORDER BY s.nick`, channelID)
 	if err != nil {
 		return nil, fmt.Errorf(
 			"query channel members: %w", err,
@@ -349,17 +405,17 @@ func (database *Database) ChannelMembers(
 	return members, nil
 }
 
-// IsChannelMember checks if a user belongs to a channel.
+// IsChannelMember checks if a session belongs to a channel.
 func (database *Database) IsChannelMember(
 	ctx context.Context,
-	channelID, userID int64,
+	channelID, sessionID int64,
 ) (bool, error) {
 	var count int
 
 	err := database.conn.QueryRowContext(ctx,
 		`SELECT COUNT(*) FROM channel_members
-		 WHERE channel_id = ? AND user_id = ?`,
-		channelID, userID,
+		 WHERE channel_id = ? AND session_id = ?`,
+		channelID, sessionID,
 	).Scan(&count)
 	if err != nil {
 		return false, fmt.Errorf(
@@ -397,13 +453,13 @@ func scanInt64s(rows *sql.Rows) ([]int64, error) {
 	return ids, nil
 }
 
-// GetChannelMemberIDs returns user IDs in a channel.
+// GetChannelMemberIDs returns session IDs in a channel.
 func (database *Database) GetChannelMemberIDs(
 	ctx context.Context,
 	channelID int64,
 ) ([]int64, error) {
 	rows, err := database.conn.QueryContext(ctx,
-		`SELECT user_id FROM channel_members
+		`SELECT session_id FROM channel_members
 		 WHERE channel_id = ?`, channelID)
 	if err != nil {
 		return nil, fmt.Errorf(
@@ -414,17 +470,17 @@ func (database *Database) GetChannelMemberIDs(
 	return scanInt64s(rows)
 }
 
-// GetUserChannelIDs returns channel IDs the user is in.
-func (database *Database) GetUserChannelIDs(
+// GetSessionChannelIDs returns channel IDs for a session.
+func (database *Database) GetSessionChannelIDs(
 	ctx context.Context,
-	userID int64,
+	sessionID int64,
 ) ([]int64, error) {
 	rows, err := database.conn.QueryContext(ctx,
 		`SELECT channel_id FROM channel_members
-		 WHERE user_id = ?`, userID)
+		 WHERE session_id = ?`, sessionID)
 	if err != nil {
 		return nil, fmt.Errorf(
-			"get user channel ids: %w", err,
+			"get session channel ids: %w", err,
 		)
 	}
 
@@ -467,27 +523,52 @@ func (database *Database) InsertMessage(
 	return dbID, msgUUID, nil
 }
 
-// EnqueueMessage adds a message to a user's queue.
-func (database *Database) EnqueueMessage(
+// EnqueueToSession adds a message to all clients of a
+// session's queues.
+func (database *Database) EnqueueToSession(
 	ctx context.Context,
-	userID, messageID int64,
+	sessionID, messageID int64,
 ) error {
 	_, err := database.conn.ExecContext(ctx,
 		`INSERT OR IGNORE INTO client_queues
-		 (user_id, message_id, created_at)
-		 VALUES (?, ?, ?)`,
-		userID, messageID, time.Now())
+		 (client_id, message_id, created_at)
+		 SELECT c.id, ?, ?
+		 FROM clients c
+		 WHERE c.session_id = ?`,
+		messageID, time.Now(), sessionID)
 	if err != nil {
-		return fmt.Errorf("enqueue message: %w", err)
+		return fmt.Errorf(
+			"enqueue to session: %w", err,
+		)
 	}
 
 	return nil
 }
 
-// PollMessages returns queued messages for a user.
+// EnqueueToClient adds a message to a specific client's
+// queue.
+func (database *Database) EnqueueToClient(
+	ctx context.Context,
+	clientID, messageID int64,
+) error {
+	_, err := database.conn.ExecContext(ctx,
+		`INSERT OR IGNORE INTO client_queues
+		 (client_id, message_id, created_at)
+		 VALUES (?, ?, ?)`,
+		clientID, messageID, time.Now())
+	if err != nil {
+		return fmt.Errorf(
+			"enqueue to client: %w", err,
+		)
+	}
+
+	return nil
+}
+
+// PollMessages returns queued messages for a client.
 func (database *Database) PollMessages(
 	ctx context.Context,
-	userID, afterQueueID int64,
+	clientID, afterQueueID int64,
 	limit int,
 ) ([]IRCMessage, int64, error) {
 	if limit <= 0 {
@@ -501,9 +582,9 @@ func (database *Database) PollMessages(
 		 FROM client_queues cq
 		 INNER JOIN messages m
 		   ON m.id = cq.message_id
-		 WHERE cq.user_id = ? AND cq.id > ?
+		 WHERE cq.client_id = ? AND cq.id > ?
 		 ORDER BY cq.id ASC LIMIT ?`,
-		userID, afterQueueID, limit)
+		clientID, afterQueueID, limit)
 	if err != nil {
 		return nil, afterQueueID, fmt.Errorf(
 			"poll messages: %w", err,
@@ -649,15 +730,15 @@ func reverseMessages(msgs []IRCMessage) {
 	}
 }
 
-// ChangeNick updates a user's nickname.
+// ChangeNick updates a session's nickname.
 func (database *Database) ChangeNick(
 	ctx context.Context,
-	userID int64,
+	sessionID int64,
 	newNick string,
 ) error {
 	_, err := database.conn.ExecContext(ctx,
-		"UPDATE users SET nick = ? WHERE id = ?",
-		newNick, userID)
+		"UPDATE sessions SET nick = ? WHERE id = ?",
+		newNick, sessionID)
 	if err != nil {
 		return fmt.Errorf("change nick: %w", err)
 	}
@@ -681,38 +762,38 @@ func (database *Database) SetTopic(
 	return nil
 }
 
-// DeleteUser removes a user and all their data.
-func (database *Database) DeleteUser(
+// DeleteSession removes a session and all its data.
+func (database *Database) DeleteSession(
 	ctx context.Context,
-	userID int64,
+	sessionID int64,
 ) error {
 	_, err := database.conn.ExecContext(
 		ctx,
-		"DELETE FROM users WHERE id = ?",
-		userID,
+		"DELETE FROM sessions WHERE id = ?",
+		sessionID,
 	)
 	if err != nil {
-		return fmt.Errorf("delete user: %w", err)
+		return fmt.Errorf("delete session: %w", err)
 	}
 
 	return nil
 }
 
-// GetAllChannelMembershipsForUser returns channels
-// a user belongs to.
-func (database *Database) GetAllChannelMembershipsForUser(
+// GetSessionChannels returns channels a session
+// belongs to.
+func (database *Database) GetSessionChannels(
 	ctx context.Context,
-	userID int64,
+	sessionID int64,
 ) ([]ChannelInfo, error) {
 	rows, err := database.conn.QueryContext(ctx,
 		`SELECT c.id, c.name, c.topic
 		 FROM channels c
 		 INNER JOIN channel_members cm
 		   ON cm.channel_id = c.id
-		 WHERE cm.user_id = ?`, userID)
+		 WHERE cm.session_id = ?`, sessionID)
 	if err != nil {
 		return nil, fmt.Errorf(
-			"get memberships: %w", err,
+			"get session channels: %w", err,
 		)
 	}
 

internal/db/queries_test.go

@@ -27,70 +27,91 @@ func setupTestDB(t *testing.T) *db.Database {
 	return database
 }
 
-func TestCreateUser(t *testing.T) {
+func TestCreateSession(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	id, token, err := database.CreateUser(ctx, "alice")
+	sessionID, _, token, err := database.CreateSession(
+		ctx, "alice",
+	)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	if id == 0 || token == "" {
+	if sessionID == 0 || token == "" {
 		t.Fatal("expected valid id and token")
 	}
 
-	_, _, err = database.CreateUser(ctx, "alice")
-	if err == nil {
+	_, _, dupToken, dupErr := database.CreateSession(
+		ctx, "alice",
+	)
+	if dupErr == nil {
 		t.Fatal("expected error for duplicate nick")
 	}
+
+	_ = dupToken
 }
 
-func TestGetUserByToken(t *testing.T) {
+func TestGetSessionByToken(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	_, token, err := database.CreateUser(ctx, "bob")
+	_, _, token, err := database.CreateSession(ctx, "bob")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	id, nick, err := database.GetUserByToken(ctx, token)
+	sessionID, clientID, nick, err :=
+		database.GetSessionByToken(ctx, token)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	if nick != "bob" || id == 0 {
+	if nick != "bob" || sessionID == 0 || clientID == 0 {
 		t.Fatalf("expected bob, got %s", nick)
 	}
 
-	_, _, err = database.GetUserByToken(ctx, "badtoken")
-	if err == nil {
+	badSID, badCID, badNick, badErr :=
+		database.GetSessionByToken(ctx, "badtoken")
+	if badErr == nil {
 		t.Fatal("expected error for bad token")
 	}
+
+	if badSID != 0 || badCID != 0 || badNick != "" {
+		t.Fatal("expected zero values on error")
+	}
 }
 
-func TestGetUserByNick(t *testing.T) {
+func TestGetSessionByNick(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	_, _, err := database.CreateUser(ctx, "charlie")
+	charlieID, charlieClientID, charlieToken, err :=
+		database.CreateSession(ctx, "charlie")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	id, err := database.GetUserByNick(ctx, "charlie")
+	if charlieID == 0 || charlieClientID == 0 {
+		t.Fatal("expected valid session/client IDs")
+	}
+
+	if charlieToken == "" {
+		t.Fatal("expected non-empty token")
+	}
+
+	id, err := database.GetSessionByNick(ctx, "charlie")
 	if err != nil || id == 0 {
 		t.Fatal("expected to find charlie")
 	}
 
-	_, err = database.GetUserByNick(ctx, "nobody")
+	_, err = database.GetSessionByNick(ctx, "nobody")
 	if err == nil {
 		t.Fatal("expected error for unknown nick")
 	}
@@ -129,7 +150,7 @@ func TestJoinAndPart(t *testing.T) {
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	uid, _, err := database.CreateUser(ctx, "user1")
+	sid, _, _, err := database.CreateSession(ctx, "user1")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -139,22 +160,22 @@ func TestJoinAndPart(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = database.JoinChannel(ctx, chID, uid)
+	err = database.JoinChannel(ctx, chID, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	ids, err := database.GetChannelMemberIDs(ctx, chID)
-	if err != nil || len(ids) != 1 || ids[0] != uid {
-		t.Fatal("expected user in channel")
+	if err != nil || len(ids) != 1 || ids[0] != sid {
+		t.Fatal("expected session in channel")
 	}
 
-	err = database.JoinChannel(ctx, chID, uid)
+	err = database.JoinChannel(ctx, chID, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	err = database.PartChannel(ctx, chID, uid)
+	err = database.PartChannel(ctx, chID, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -178,17 +199,17 @@ func TestDeleteChannelIfEmpty(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	uid, _, err := database.CreateUser(ctx, "temp")
+	sid, _, _, err := database.CreateSession(ctx, "temp")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	err = database.JoinChannel(ctx, chID, uid)
+	err = database.JoinChannel(ctx, chID, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	err = database.PartChannel(ctx, chID, uid)
+	err = database.PartChannel(ctx, chID, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -204,7 +225,7 @@ func TestDeleteChannelIfEmpty(t *testing.T) {
 	}
 }
 
-func createUserWithChannels(
+func createSessionWithChannels(
 	t *testing.T,
 	database *db.Database,
 	nick, ch1Name, ch2Name string,
@@ -213,7 +234,7 @@ func createUserWithChannels(
 
 	ctx := t.Context()
 
-	uid, _, err := database.CreateUser(ctx, nick)
+	sid, _, _, err := database.CreateSession(ctx, nick)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -232,29 +253,29 @@ func createUserWithChannels(
 		t.Fatal(err)
 	}
 
-	err = database.JoinChannel(ctx, ch1, uid)
+	err = database.JoinChannel(ctx, ch1, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	err = database.JoinChannel(ctx, ch2, uid)
+	err = database.JoinChannel(ctx, ch2, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	return uid, ch1, ch2
+	return sid, ch1, ch2
 }
 
 func TestListChannels(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
-	uid, _, _ := createUserWithChannels(
+	sid, _, _ := createSessionWithChannels(
 		t, database, "lister", "#a", "#b",
 	)
 
 	channels, err := database.ListChannels(
-		t.Context(), uid,
+		t.Context(), sid,
 	)
 	if err != nil || len(channels) != 2 {
 		t.Fatalf(
@@ -295,17 +316,21 @@ func TestChangeNick(t *testing.T) {
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	uid, token, err := database.CreateUser(ctx, "old")
+	sid, _, token, err := database.CreateSession(
+		ctx, "old",
+	)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	err = database.ChangeNick(ctx, uid, "new")
+	err = database.ChangeNick(ctx, sid, "new")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	_, nick, err := database.GetUserByToken(ctx, token)
+	_, _, nick, err := database.GetSessionByToken(
+		ctx, token,
+	)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -375,7 +400,16 @@ func TestPollMessages(t *testing.T) {
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	uid, _, err := database.CreateUser(ctx, "poller")
+	sid, _, token, err := database.CreateSession(
+		ctx, "poller",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, clientID, _, err := database.GetSessionByToken(
+		ctx, token,
+	)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -389,7 +423,7 @@ func TestPollMessages(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = database.EnqueueMessage(ctx, uid, dbID)
+	err = database.EnqueueToSession(ctx, sid, dbID)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -397,7 +431,7 @@ func TestPollMessages(t *testing.T) {
 	const batchSize = 10
 
 	msgs, lastQID, err := database.PollMessages(
-		ctx, uid, 0, batchSize,
+		ctx, clientID, 0, batchSize,
 	)
 	if err != nil {
 		t.Fatal(err)
@@ -420,7 +454,7 @@ func TestPollMessages(t *testing.T) {
 	}
 
 	msgs, _, _ = database.PollMessages(
-		ctx, uid, lastQID, batchSize,
+		ctx, clientID, lastQID, batchSize,
 	)
 
 	if len(msgs) != 0 {
@@ -467,13 +501,15 @@ func TestGetHistory(t *testing.T) {
 	}
 }
 
-func TestDeleteUser(t *testing.T) {
+func TestDeleteSession(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	uid, _, err := database.CreateUser(ctx, "deleteme")
+	sid, _, _, err := database.CreateSession(
+		ctx, "deleteme",
+	)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -485,19 +521,19 @@ func TestDeleteUser(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = database.JoinChannel(ctx, chID, uid)
+	err = database.JoinChannel(ctx, chID, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	err = database.DeleteUser(ctx, uid)
+	err = database.DeleteSession(ctx, sid)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	_, err = database.GetUserByNick(ctx, "deleteme")
+	_, err = database.GetSessionByNick(ctx, "deleteme")
 	if err == nil {
-		t.Fatal("user should be deleted")
+		t.Fatal("session should be deleted")
 	}
 
 	ids, _ := database.GetChannelMemberIDs(ctx, chID)
@@ -512,12 +548,12 @@ func TestChannelMembers(t *testing.T) {
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	uid1, _, err := database.CreateUser(ctx, "m1")
+	sid1, _, _, err := database.CreateSession(ctx, "m1")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	uid2, _, err := database.CreateUser(ctx, "m2")
+	sid2, _, _, err := database.CreateSession(ctx, "m2")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -529,12 +565,12 @@ func TestChannelMembers(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	err = database.JoinChannel(ctx, chID, uid1)
+	err = database.JoinChannel(ctx, chID, sid1)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	err = database.JoinChannel(ctx, chID, uid2)
+	err = database.JoinChannel(ctx, chID, sid2)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -548,17 +584,17 @@ func TestChannelMembers(t *testing.T) {
 	}
 }
 
-func TestGetAllChannelMembershipsForUser(t *testing.T) {
+func TestGetSessionChannels(t *testing.T) {
 	t.Parallel()
 
 	database := setupTestDB(t)
-	uid, _, _ := createUserWithChannels(
+	sid, _, _ := createSessionWithChannels(
 		t, database, "multi", "#m1", "#m2",
 	)
 
 	channels, err :=
-		database.GetAllChannelMembershipsForUser(
-			t.Context(), uid,
+		database.GetSessionChannels(
+			t.Context(), sid,
 		)
 	if err != nil || len(channels) != 2 {
 		t.Fatalf(
@@ -567,3 +603,51 @@ func TestGetAllChannelMembershipsForUser(t *testing.T) {
 		)
 	}
 }
+
+func TestEnqueueToClient(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	_, _, token, err := database.CreateSession(
+		ctx, "enqclient",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, clientID, _, err := database.GetSessionByToken(
+		ctx, token,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	body := json.RawMessage(`["test"]`)
+
+	dbID, _, err := database.InsertMessage(
+		ctx, "PRIVMSG", "sender", "#ch", body, nil,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = database.EnqueueToClient(ctx, clientID, dbID)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	const batchSize = 10
+
+	msgs, _, err := database.PollMessages(
+		ctx, clientID, 0, batchSize,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(msgs) != 1 {
+		t.Fatalf("expected 1, got %d", len(msgs))
+	}
+}

internal/db/schema/001_initial.sql

@@ -1,15 +1,28 @@
 -- Chat server schema (pre-1.0 consolidated)
 PRAGMA foreign_keys = ON;
 
--- Users: IRC-style sessions (no passwords, just nick + token)
-CREATE TABLE IF NOT EXISTS users (
+-- Sessions: IRC-style sessions (no passwords, nick + optional signing key)
+CREATE TABLE IF NOT EXISTS sessions (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
+    uuid TEXT NOT NULL UNIQUE,
     nick TEXT NOT NULL UNIQUE,
+    signing_key TEXT NOT NULL DEFAULT '',
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    last_seen DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+CREATE INDEX IF NOT EXISTS idx_sessions_uuid ON sessions(uuid);
+
+-- Clients: each session can have multiple connected clients
+CREATE TABLE IF NOT EXISTS clients (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    uuid TEXT NOT NULL UNIQUE,
+    session_id INTEGER NOT NULL REFERENCES sessions(id) ON DELETE CASCADE,
     token TEXT NOT NULL UNIQUE,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     last_seen DATETIME DEFAULT CURRENT_TIMESTAMP
 );
-CREATE INDEX IF NOT EXISTS idx_users_token ON users(token);
+CREATE INDEX IF NOT EXISTS idx_clients_token ON clients(token);
+CREATE INDEX IF NOT EXISTS idx_clients_session ON clients(session_id);
 
 -- Channels
 CREATE TABLE IF NOT EXISTS channels (
@@ -24,9 +37,9 @@ CREATE TABLE IF NOT EXISTS channels (
 CREATE TABLE IF NOT EXISTS channel_members (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
     channel_id INTEGER NOT NULL REFERENCES channels(id) ON DELETE CASCADE,
-    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    session_id INTEGER NOT NULL REFERENCES sessions(id) ON DELETE CASCADE,
     joined_at DATETIME DEFAULT CURRENT_TIMESTAMP,
-    UNIQUE(channel_id, user_id)
+    UNIQUE(channel_id, session_id)
 );
 
 -- Messages: IRC envelope format
@@ -46,9 +59,9 @@ CREATE INDEX IF NOT EXISTS idx_messages_created ON messages(created_at);
 -- Per-client message queues for fan-out delivery
 CREATE TABLE IF NOT EXISTS client_queues (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
-    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    client_id INTEGER NOT NULL REFERENCES clients(id) ON DELETE CASCADE,
     message_id INTEGER NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
-    UNIQUE(user_id, message_id)
+    UNIQUE(client_id, message_id)
 );
-CREATE INDEX IF NOT EXISTS idx_client_queues_user ON client_queues(user_id, id);
+CREATE INDEX IF NOT EXISTS idx_client_queues_client ON client_queues(client_id, id);