diff --git a/internal/db/auth.go b/internal/db/auth.go
index 4927853..03e8999 100644
--- a/internal/db/auth.go
+++ b/internal/db/auth.go
@@ -10,13 +10,6 @@ import (
 	"golang.org/x/crypto/bcrypt"
 )
 
-//nolint:gochecknoglobals // var so tests can override via SetBcryptCost
-var bcryptCost = bcrypt.DefaultCost
-
-// SetBcryptCost overrides the bcrypt cost.
-// Use bcrypt.MinCost in tests to avoid slow hashing.
-func SetBcryptCost(cost int) { bcryptCost = cost }
-
 var errNoPassword = errors.New(
 	"account has no password set",
 )
@@ -29,7 +22,7 @@ func (database *Database) SetPassword(
 	password string,
 ) error {
 	hash, err := bcrypt.GenerateFromPassword(
-		[]byte(password), bcryptCost,
+		[]byte(password), bcrypt.DefaultCost,
 	)
 	if err != nil {
 		return fmt.Errorf("hash password: %w", err)
diff --git a/internal/db/db.go b/internal/db/db.go
index b669061..922ee2e 100644
--- a/internal/db/db.go
+++ b/internal/db/db.go
@@ -85,11 +85,6 @@ func New(
 	return database, nil
 }
 
-// GetDB returns the underlying sql.DB connection.
-func (database *Database) GetDB() *sql.DB {
-	return database.conn
-}
-
 func (database *Database) connect(ctx context.Context) error {
 	dbURL := database.params.Config.DBURL
 	if dbURL == "" {
diff --git a/internal/db/export_test.go b/internal/db/export_test.go
index 5dd9384..f24537c 100644
--- a/internal/db/export_test.go
+++ b/internal/db/export_test.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"log/slog"
 	"testing"
+	"time"
 
 	"sneak.berlin/go/neoirc/internal/dbtest"
 )
@@ -67,3 +68,78 @@ func (database *Database) ExecForTest(
 
 	return nil
 }
+
+// GetDB returns the underlying sql.DB connection.
+func (database *Database) GetDB() *sql.DB {
+	return database.conn
+}
+
+// GetOrCreateChannel returns channel id, creating if needed.
+// Uses INSERT OR IGNORE to avoid TOCTOU races.
+func (database *Database) GetOrCreateChannel(
+	ctx context.Context,
+	name string,
+) (int64, error) {
+	now := time.Now()
+
+	_, err := database.conn.ExecContext(ctx,
+		`INSERT OR IGNORE INTO channels
+		 (name, created_at, updated_at)
+		 VALUES (?, ?, ?)`,
+		name, now, now)
+	if err != nil {
+		return 0, fmt.Errorf("create channel: %w", err)
+	}
+
+	var channelID int64
+
+	err = database.conn.QueryRowContext(
+		ctx,
+		"SELECT id FROM channels WHERE name = ?",
+		name,
+	).Scan(&channelID)
+	if err != nil {
+		return 0, fmt.Errorf("get channel: %w", err)
+	}
+
+	return channelID, nil
+}
+
+// JoinChannel adds a session to a channel.
+func (database *Database) JoinChannel(
+	ctx context.Context,
+	channelID, sessionID int64,
+) error {
+	_, err := database.conn.ExecContext(ctx,
+		`INSERT OR IGNORE INTO channel_members
+		 (channel_id, session_id, joined_at)
+		 VALUES (?, ?, ?)`,
+		channelID, sessionID, time.Now())
+	if err != nil {
+		return fmt.Errorf("join channel: %w", err)
+	}
+
+	return nil
+}
+
+// HasChannelInvite checks if a session has been invited
+// to a channel.
+func (database *Database) HasChannelInvite(
+	ctx context.Context,
+	channelID, sessionID int64,
+) (bool, error) {
+	var count int
+
+	err := database.conn.QueryRowContext(ctx,
+		`SELECT COUNT(*) FROM channel_invites
+		 WHERE channel_id = ? AND session_id = ?`,
+		channelID, sessionID,
+	).Scan(&count)
+	if err != nil {
+		return false, fmt.Errorf(
+			"check invite: %w", err,
+		)
+	}
+
+	return count > 0, nil
+}
diff --git a/internal/db/main_test.go b/internal/db/main_test.go
deleted file mode 100644
index e9cd045..0000000
--- a/internal/db/main_test.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package db_test
-
-import (
-	"os"
-	"testing"
-
-	"golang.org/x/crypto/bcrypt"
-	"sneak.berlin/go/neoirc/internal/db"
-)
-
-func TestMain(m *testing.M) {
-	db.SetBcryptCost(bcrypt.MinCost)
-	os.Exit(m.Run())
-}
diff --git a/internal/db/queries.go b/internal/db/queries.go
index e83e2a0..f50839d 100644
--- a/internal/db/queries.go
+++ b/internal/db/queries.go
@@ -320,29 +320,6 @@ type ClientHostInfo struct {
 	Hostname string
 }
 
-// GetClientHostInfo returns the IP and hostname for a
-// client.
-func (database *Database) GetClientHostInfo(
-	ctx context.Context,
-	clientID int64,
-) (*ClientHostInfo, error) {
-	var info ClientHostInfo
-
-	err := database.conn.QueryRowContext(
-		ctx,
-		`SELECT ip, hostname
-		 FROM clients WHERE id = ?`,
-		clientID,
-	).Scan(&info.IP, &info.Hostname)
-	if err != nil {
-		return nil, fmt.Errorf(
-			"get client host info: %w", err,
-		)
-	}
-
-	return &info, nil
-}
-
 // SetSessionOper sets the is_oper flag on a session.
 func (database *Database) SetSessionOper(
 	ctx context.Context,
@@ -433,54 +410,6 @@ func (database *Database) GetChannelByName(
 	return channelID, nil
 }
 
-// GetOrCreateChannel returns channel id, creating if needed.
-// Uses INSERT OR IGNORE to avoid TOCTOU races.
-func (database *Database) GetOrCreateChannel(
-	ctx context.Context,
-	name string,
-) (int64, error) {
-	now := time.Now()
-
-	_, err := database.conn.ExecContext(ctx,
-		`INSERT OR IGNORE INTO channels
-		 (name, created_at, updated_at)
-		 VALUES (?, ?, ?)`,
-		name, now, now)
-	if err != nil {
-		return 0, fmt.Errorf("create channel: %w", err)
-	}
-
-	var channelID int64
-
-	err = database.conn.QueryRowContext(
-		ctx,
-		"SELECT id FROM channels WHERE name = ?",
-		name,
-	).Scan(&channelID)
-	if err != nil {
-		return 0, fmt.Errorf("get channel: %w", err)
-	}
-
-	return channelID, nil
-}
-
-// JoinChannel adds a session to a channel.
-func (database *Database) JoinChannel(
-	ctx context.Context,
-	channelID, sessionID int64,
-) error {
-	_, err := database.conn.ExecContext(ctx,
-		`INSERT OR IGNORE INTO channel_members
-		 (channel_id, session_id, joined_at)
-		 VALUES (?, ?, ?)`,
-		channelID, sessionID, time.Now())
-	if err != nil {
-		return fmt.Errorf("join channel: %w", err)
-	}
-
-	return nil
-}
-
 // Errors that CreateOrJoinChannel refuses a join with.
 var (
 	ErrBannedFromChannel = errors.New("banned from channel")
@@ -2460,28 +2389,6 @@ func (database *Database) AddChannelInvite(
 	return nil
 }
 
-// HasChannelInvite checks if a session has been invited
-// to a channel.
-func (database *Database) HasChannelInvite(
-	ctx context.Context,
-	channelID, sessionID int64,
-) (bool, error) {
-	var count int
-
-	err := database.conn.QueryRowContext(ctx,
-		`SELECT COUNT(*) FROM channel_invites
-		 WHERE channel_id = ? AND session_id = ?`,
-		channelID, sessionID,
-	).Scan(&count)
-	if err != nil {
-		return false, fmt.Errorf(
-			"check invite: %w", err,
-		)
-	}
-
-	return count > 0, nil
-}
-
 // --- Tier 2: Secret (+s) ---
 
 // IsChannelSecret checks if a channel has +s mode.
diff --git a/internal/db/queries_test.go b/internal/db/queries_test.go
index a39f88a..c44ea2a 100644
--- a/internal/db/queries_test.go
+++ b/internal/db/queries_test.go
@@ -125,7 +125,7 @@ func TestCreateSessionStoresIP(t *testing.T) {
 	database := setupTestDB(t)
 	ctx := t.Context()
 
-	sessionID, clientID, _, err := database.CreateSession(
+	sessionID, _, _, err := database.CreateSession(
 		ctx, "ipuser", "ident", "host.example.com",
 		"192.168.1.42",
 	)
@@ -147,8 +147,8 @@ func TestCreateSessionStoresIP(t *testing.T) {
 		)
 	}
 
-	clientInfo, err := database.GetClientHostInfo(
-		ctx, clientID,
+	clientInfo, err := database.GetLatestClientForSession(
+		ctx, sessionID,
 	)
 	if err != nil {
 		t.Fatal(err)
@@ -169,19 +169,6 @@ func TestCreateSessionStoresIP(t *testing.T) {
 	}
 }
 
-func TestGetClientHostInfoNotFound(t *testing.T) {
-	t.Parallel()
-
-	database := setupTestDB(t)
-
-	_, err := database.GetClientHostInfo(
-		t.Context(), 99999,
-	)
-	if err == nil {
-		t.Fatal("expected error for nonexistent client")
-	}
-}
-
 func TestGetSessionHostInfoNotFound(t *testing.T) {
 	t.Parallel()
 
diff --git a/internal/db/testing.go b/internal/db/testing.go
deleted file mode 100644
index d036611..0000000
--- a/internal/db/testing.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package db
-
-import (
-	"context"
-	"database/sql"
-	"log/slog"
-)
-
-// NewTestDatabaseFromConn creates a Database wrapping an
-// existing *sql.DB connection.  Intended for integration
-// tests in other packages.
-func NewTestDatabaseFromConn(conn *sql.DB) *Database {
-	return &Database{ //nolint:exhaustruct
-		conn: conn,
-		log:  slog.Default(),
-	}
-}
-
-// RunMigrations applies all schema migrations.  Exposed
-// for integration tests in other packages.
-func (database *Database) RunMigrations(
-	ctx context.Context,
-) error {
-	return database.runMigrations(ctx)
-}
diff --git a/internal/dbtest/dbtest.go b/internal/dbtest/dbtest.go
index add7f03..8346bf1 100644
--- a/internal/dbtest/dbtest.go
+++ b/internal/dbtest/dbtest.go
@@ -1,5 +1,5 @@
-// Package dbtest gives each test a database of its own. Only tests
-// may import it.
+// Package dbtest gives each test a database of its own and runs raw
+// SQL on it. Only tests may import it.
 package dbtest
 
 import (
@@ -37,3 +37,23 @@ func NewURL(tb testing.TB) string {
 
 	return dbURL
 }
+
+// Exec runs one raw SQL statement on the database at dbURL, over a
+// connection of its own. A test uses it for what the methods of
+// db.Database cannot do, such as creating a trigger that makes a
+// write fail.
+func Exec(tb testing.TB, dbURL, statement string) {
+	tb.Helper()
+
+	pool, err := sql.Open("sqlite", dbURL)
+	if err != nil {
+		tb.Fatalf("open test database: %v", err)
+	}
+
+	defer func() { _ = pool.Close() }()
+
+	_, err = pool.ExecContext(tb.Context(), statement)
+	if err != nil {
+		tb.Fatalf("run %q: %v", statement, err)
+	}
+}
diff --git a/internal/handlers/api_test.go b/internal/handlers/api_test.go
index 305be3f..0c065e7 100644
--- a/internal/handlers/api_test.go
+++ b/internal/handlers/api_test.go
@@ -23,7 +23,6 @@ import (
 
 	"go.uber.org/fx"
 	"go.uber.org/fx/fxtest"
-	"golang.org/x/crypto/bcrypt"
 	"modernc.org/sqlite"
 	"sneak.berlin/go/neoirc/internal/broker"
 	api "sneak.berlin/go/neoirc/internal/cli/api"
@@ -47,22 +46,25 @@ import (
 const templateDBURL = "file:template?mode=memory&cache=shared"
 
 func TestMain(m *testing.M) {
-	db.SetBcryptCost(bcrypt.MinCost)
+	template := fx.New(
+		fx.NopLogger,
+		fx.Supply(
+			&globals.Globals{},
+			&config.Config{DBURL: templateDBURL},
+		),
+		fx.Provide(logger.New, newTestDB),
+		// fx makes the database only if something asks for it.
+		fx.Invoke(func(*db.Database) {}),
+	)
 
-	template, err := sql.Open("sqlite", templateDBURL)
-	if err != nil {
-		panic(err)
-	}
-
-	err = db.NewTestDatabaseFromConn(template).
-		RunMigrations(context.Background())
+	err := template.Start(context.Background())
 	if err != nil {
 		panic(err)
 	}
 
 	code := m.Run()
 
-	_ = template.Close()
+	_ = template.Stop(context.Background())
 
 	os.Exit(code)
 }
@@ -137,6 +139,7 @@ type testServer struct {
 	t          *testing.T
 	fxApp      *fxtest.App
 	broker     *broker.Broker
+	dbURL      string
 	database   *db.Database
 	handlers   *handlers.Handlers
 }
@@ -231,6 +234,7 @@ func newTestServerWith(
 		t:          t,
 		fxApp:      app,
 		broker:     brk,
+		dbURL:      dbURL,
 		database:   database,
 		handlers:   hdlr,
 	}
@@ -1887,15 +1891,12 @@ func TestFailedLogoutChangesNothing(t *testing.T) {
 
 	_, lastID := tserver.pollMessages(observerToken, 0)
 
-	_, err := tserver.database.GetDB().ExecContext(t.Context(),
+	dbtest.Exec(t, tserver.dbURL,
 		`CREATE TRIGGER keep_sessions
 		 BEFORE DELETE ON sessions
 		 BEGIN
 		   SELECT RAISE(ABORT, 'sessions are kept');
 		 END`)
-	if err != nil {
-		t.Fatal(err)
-	}
 
 	resp, err := doRequestAuth(
 		t, http.MethodPost, tserver.url(apiLogout), token, nil,
diff --git a/internal/ircserver/server_test.go b/internal/ircserver/server_test.go
index bff359c..2ca7d02 100644
--- a/internal/ircserver/server_test.go
+++ b/internal/ircserver/server_test.go
@@ -32,14 +32,9 @@ import (
 
 const testTimeout = 5 * time.Second
 
-func TestMain(m *testing.M) {
-	db.SetBcryptCost(4)
-
-	os.Exit(m.Run())
-}
-
 // testEnv holds the shared test infrastructure.
 type testEnv struct {
+	dbURL    string
 	database *db.Database
 	brk      *broker.Broker
 	cfg      *config.Config
@@ -110,34 +105,27 @@ func newTestEnvWithResolver(
 ) *testEnv {
 	t.Helper()
 
-	conn, err := sql.Open("sqlite", dbtest.NewURL(t))
-	if err != nil {
-		t.Fatalf("open db: %v", err)
-	}
+	dbURL := dbtest.NewURL(t)
+	lifecycle := fxtest.NewLifecycle(t)
 
-	t.Cleanup(func() {
-		err := conn.Close()
-		if err != nil {
-			t.Logf("close db: %v", err)
-		}
+	dbLog, err := logger.New(lifecycle, logger.Params{
+		Globals: &globals.Globals{},
 	})
-
-	conn.SetMaxOpenConns(1)
-
-	_, err = conn.ExecContext(
-		t.Context(), "PRAGMA foreign_keys = ON",
-	)
 	if err != nil {
-		t.Fatalf("pragma: %v", err)
+		t.Fatalf("new logger: %v", err)
 	}
 
-	database := db.NewTestDatabaseFromConn(conn)
-
-	err = database.RunMigrations(t.Context())
+	database, err := db.New(lifecycle, db.Params{
+		Logger: dbLog,
+		Config: &config.Config{DBURL: dbURL},
+	})
 	if err != nil {
-		t.Fatalf("migrate: %v", err)
+		t.Fatalf("new database: %v", err)
 	}
 
+	lifecycle.RequireStart()
+	t.Cleanup(lifecycle.RequireStop)
+
 	brk := broker.New()
 
 	log := slog.New(slog.NewTextHandler(
@@ -161,6 +149,7 @@ func newTestEnvWithResolver(
 	t.Cleanup(srv.Stop)
 
 	return &testEnv{
+		dbURL:    dbURL,
 		database: database,
 		brk:      brk,
 		cfg:      cfg,
@@ -929,12 +918,7 @@ func quitSeenByPeers(t *testing.T, quit string) (string, []string) {
 		t.Fatalf("create peer session: %v", err)
 	}
 
-	channelID, err := env.database.GetChannelByName(ctx, "#bye")
-	if err != nil {
-		t.Fatalf("get channel: %v", err)
-	}
-
-	err = env.database.JoinChannel(ctx, channelID, apiPeerID)
+	_, _, err = env.database.CreateOrJoinChannel(ctx, "#bye", apiPeerID, "")
 	if err != nil {
 		t.Fatalf("join peer: %v", err)
 	}
@@ -1005,12 +989,9 @@ func TestStopEndsSessions(t *testing.T) {
 		t.Fatalf("create peer session: %v", err)
 	}
 
-	channelID, err := env.database.GetChannelByName(ctx, "#shut")
-	if err != nil {
-		t.Fatalf("get channel: %v", err)
-	}
-
-	err = env.database.JoinChannel(ctx, channelID, peerID)
+	channelID, _, err := env.database.CreateOrJoinChannel(
+		ctx, "#shut", peerID, "",
+	)
 	if err != nil {
 		t.Fatalf("join peer: %v", err)
 	}
@@ -1068,11 +1049,16 @@ func TestStopReturnsWhileCleanupIsStuck(t *testing.T) {
 
 	client.register("stuck")
 
-	// The test database has one connection. While the test
-	// holds it, the cleanup's first query waits for it.
-	held, err := env.database.GetDB().Conn(t.Context())
+	// While a connection of the test's own holds a write
+	// transaction, the cleanup's first write waits for it to end.
+	holder, err := sql.Open("sqlite", env.dbURL)
 	if err != nil {
-		t.Fatalf("take the database connection: %v", err)
+		t.Fatalf("open a second database connection: %v", err)
+	}
+
+	_, err = holder.ExecContext(t.Context(), "BEGIN IMMEDIATE")
+	if err != nil {
+		t.Fatalf("begin a write transaction: %v", err)
 	}
 
 	stopped := make(chan struct{})
@@ -1088,10 +1074,11 @@ func TestStopReturnsWhileCleanupIsStuck(t *testing.T) {
 		t.Error("Stop did not return while a cleanup was stuck")
 	}
 
-	// Lets the cleanup finish before the database is closed.
-	err = held.Close()
+	// Closing ends the transaction, which lets the cleanup finish
+	// before the database is closed.
+	err = holder.Close()
 	if err != nil {
-		t.Errorf("release the database connection: %v", err)
+		t.Errorf("close the second database connection: %v", err)
 	}
 }
 
@@ -1370,14 +1357,11 @@ func TestPassPostRegistrationNotStored(t *testing.T) {
 
 	client.register("failpass")
 
-	_, err := env.database.GetDB().ExecContext(t.Context(),
+	dbtest.Exec(t, env.dbURL,
 		`CREATE TRIGGER refuse_password
 		 BEFORE UPDATE OF password_hash ON sessions
 		 BEGIN SELECT RAISE(ABORT, 'refused'); END`,
 	)
-	if err != nil {
-		t.Fatalf("create trigger: %v", err)
-	}
 
 	client.send("PASS :mypassword123")
 
diff --git a/internal/service/service_test.go b/internal/service/service_test.go
index a51710a..f27eff8 100644
--- a/internal/service/service_test.go
+++ b/internal/service/service_test.go
@@ -9,7 +9,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"os"
 	"slices"
 	"strings"
 	"sync"
@@ -18,7 +17,6 @@ import (
 
 	"go.uber.org/fx"
 	"go.uber.org/fx/fxtest"
-	"golang.org/x/crypto/bcrypt"
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
@@ -30,14 +28,10 @@ import (
 	"sneak.berlin/go/neoirc/pkg/irc"
 )
 
-func TestMain(m *testing.M) {
-	db.SetBcryptCost(bcrypt.MinCost)
-	os.Exit(m.Run())
-}
-
 // testEnv holds all dependencies for a service test.
 type testEnv struct {
 	svc    *service.Service
+	dbURL  string
 	db     *db.Database
 	broker *broker.Broker
 	app    *fxtest.App
@@ -111,6 +105,7 @@ func newTestEnv(t *testing.T) *testEnv {
 
 	return &testEnv{
 		svc:    svc,
+		dbURL:  dbURL,
 		db:     database,
 		broker: brk,
 		app:    app,
@@ -940,19 +935,16 @@ func TestSendDirectMessageTargetQuits(t *testing.T) {
 	sid := createSession(ctx, t, env.db, "alice")
 	createSession(ctx, t, env.db, "bob")
 
-	_, err := env.db.GetDB().ExecContext(ctx,
+	dbtest.Exec(t, env.dbURL,
 		`CREATE TRIGGER delete_recipient
 		 BEFORE INSERT ON messages
 		 BEGIN
 		   DELETE FROM sessions WHERE id = NEW.to_session_id;
 		 END`)
-	if err != nil {
-		t.Fatalf("create trigger: %v", err)
-	}
 
 	body, _ := json.Marshal([]string{"hi"}) //nolint:errchkjson
 
-	_, err = env.svc.SendDirectMessage(
+	_, err := env.svc.SendDirectMessage(
 		ctx, sid, 0, "alice", irc.CmdPrivmsg, "bob", body, nil,
 	)
 
@@ -978,15 +970,12 @@ func TestSendChannelMessageChannelDeleted(t *testing.T) {
 		t.Fatalf("join alice: %v", err)
 	}
 
-	_, err = env.db.GetDB().ExecContext(ctx,
+	dbtest.Exec(t, env.dbURL,
 		`CREATE TRIGGER delete_recipient
 		 BEFORE INSERT ON messages
 		 BEGIN
 		   DELETE FROM channels WHERE id = NEW.to_channel_id;
 		 END`)
-	if err != nil {
-		t.Fatalf("create trigger: %v", err)
-	}
 
 	body, _ := json.Marshal([]string{"hi"}) //nolint:errchkjson