diff --git a/db/pg/pg.go b/db/pg/pg.go
index 3b034736..015910d6 100644
--- a/db/pg/pg.go
+++ b/db/pg/pg.go
@@ -13,6 +13,12 @@ import (
 	"heckel.io/ntfy/v2/db"
 )
 
+// Advisory lock keys. PostgreSQL advisory locks share one database-wide key space, so every
+// ntfy key is defined here, following the "ntfy"+2586+letter scheme
+const (
+	SchemaLockKey = int64(0x6e7466792586a) // Schema setup serialization (transaction-scoped, see db/schema)
+)
+
 // Open opens a PostgreSQL connection pool for a primary database. It pings the database
 // to verify connectivity before returning.
 func Open(dsn string) (*db.Host, error) {
diff --git a/db/schema/schema.go b/db/schema/schema.go
new file mode 100644
index 00000000..f4f97b7c
--- /dev/null
+++ b/db/schema/schema.go
@@ -0,0 +1,127 @@
+// Package schema tracks and migrates database schemas, and Migrate creates or upgrades a
+// store's schema inside a single transaction. On PostgreSQL, all stores share one database, so
+// versions live in a shared schema_version table keyed by store name. On SQLite, every store is
+// its own database file, so the version lives in the schemaVersion table keyed by id = 1 -- the
+// exact layout pre-existing ntfy SQLite databases already use, which lets them migrate onto
+// this framework without an adoption step.
+package schema
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"heckel.io/ntfy/v2/db/pg"
+)
+
+// Queries by dialect; the version table is shared by all stores on Postgres, and per database
+// file on SQLite
+const (
+	postgresCreateVersionTableQuery = `CREATE TABLE IF NOT EXISTS schema_version (store TEXT PRIMARY KEY, version INT NOT NULL)`
+	postgresSelectVersionQuery      = `SELECT version FROM schema_version WHERE store = $1`
+	postgresUpsertVersionQuery      = `INSERT INTO schema_version (store, version) VALUES ($1, $2) ON CONFLICT (store) DO UPDATE SET version = EXCLUDED.version`
+	postgresAdvisoryLockQuery       = `SELECT pg_advisory_xact_lock($1)`
+
+	sqliteCreateVersionTableQuery = `CREATE TABLE IF NOT EXISTS schemaVersion (id INT PRIMARY KEY, version INT NOT NULL)`
+	sqliteSelectVersionQuery      = `SELECT version FROM schemaVersion WHERE id = 1`
+	sqliteUpsertVersionQuery      = `INSERT INTO schemaVersion (id, version) VALUES (1, ?) ON CONFLICT (id) DO UPDATE SET version = excluded.version`
+)
+
+// Dialect selects the SQL flavor Migrate speaks to the version table.
+type Dialect int
+
+// Supported dialects; SQLite is the zero value
+const (
+	SQLite Dialect = iota
+	Postgres
+)
+
+// MigrateFunc applies one schema change inside the setup transaction: the initial creation of
+// a store's tables, or one step upgrading a store from version N to N+1. Migrations needing
+// config capture it via closure, e.g. func migrations(cacheDuration time.Duration) map[int]MigrateFunc.
+type MigrateFunc func(tx *sql.Tx) error
+
+// Migrate creates or upgrades the named store's schema to targetVersion in one transaction: a
+// fresh database gets the create func; an existing one is upgraded step by step through the
+// migrations map (keyed by the FROM version; always append, never insert in the middle); a
+// schema migrated by newer code is refused. A failed migration rolls back atomically. Caveats:
+// statements that refuse transaction blocks (Postgres CREATE INDEX CONCURRENTLY, VACUUM) cannot
+// go through Migrate, and DDL holds exclusive locks until commit, so keep migrations fast.
+func Migrate(db *sql.DB, dialect Dialect, store string, targetVersion int, create MigrateFunc, migrations map[int]MigrateFunc) error {
+	if dialect != Postgres && dialect != SQLite {
+		return fmt.Errorf("unsupported schema dialect %d", dialect)
+	}
+	tx, err := db.Begin()
+	if err != nil {
+		return fmt.Errorf("cannot begin %s schema transaction: %w", store, err)
+	}
+	defer tx.Rollback()
+	if dialect == Postgres {
+		// Serialize setup across nodes: CREATE TABLE IF NOT EXISTS is not atomic, and
+		// concurrently cold-booting nodes would otherwise race on DDL and crash
+		if _, err := tx.Exec(postgresAdvisoryLockQuery, pg.SchemaLockKey); err != nil {
+			return fmt.Errorf("cannot acquire %s schema advisory lock: %w", store, err)
+		}
+	}
+	if _, err := tx.Exec(createVersionTableQuery(dialect)); err != nil {
+		return fmt.Errorf("cannot create schema version table: %w", err)
+	}
+	version, err := readVersion(tx, dialect, store)
+	if errors.Is(err, sql.ErrNoRows) {
+		// Fresh database: create the store's tables at the target version
+		if err := create(tx); err != nil {
+			return fmt.Errorf("cannot create %s schema: %w", store, err)
+		}
+		if err := writeVersion(tx, dialect, store, targetVersion); err != nil {
+			return fmt.Errorf("cannot write %s schema version: %w", store, err)
+		}
+		return tx.Commit()
+	} else if err != nil {
+		return fmt.Errorf("cannot read %s schema version: %w", store, err)
+	}
+	if version == targetVersion {
+		return tx.Commit()
+	}
+	if version > targetVersion {
+		return fmt.Errorf("unexpected %s schema version %d, this version of ntfy supports up to %d", store, version, targetVersion)
+	}
+	for v := version; v < targetVersion; v++ {
+		migrate, ok := migrations[v]
+		if !ok {
+			return fmt.Errorf("cannot find %s migration step from version %d to %d", store, v, v+1)
+		}
+		if err := migrate(tx); err != nil {
+			return fmt.Errorf("%s migration step from version %d to %d failed: %w", store, v, v+1, err)
+		}
+	}
+	if err := writeVersion(tx, dialect, store, targetVersion); err != nil {
+		return fmt.Errorf("cannot write %s schema version: %w", store, err)
+	}
+	return tx.Commit()
+}
+
+func createVersionTableQuery(dialect Dialect) string {
+	if dialect == Postgres {
+		return postgresCreateVersionTableQuery
+	}
+	return sqliteCreateVersionTableQuery
+}
+
+func readVersion(tx *sql.Tx, dialect Dialect, store string) (version int, err error) {
+	if dialect == Postgres {
+		err = tx.QueryRow(postgresSelectVersionQuery, store).Scan(&version)
+	} else {
+		err = tx.QueryRow(sqliteSelectVersionQuery).Scan(&version)
+	}
+	return
+}
+
+func writeVersion(tx *sql.Tx, dialect Dialect, store string, version int) error {
+	var err error
+	if dialect == Postgres {
+		_, err = tx.Exec(postgresUpsertVersionQuery, store, version)
+	} else {
+		_, err = tx.Exec(sqliteUpsertVersionQuery, version)
+	}
+	return err
+}
diff --git a/db/schema/schema_test.go b/db/schema/schema_test.go
new file mode 100644
index 00000000..9d848e94
--- /dev/null
+++ b/db/schema/schema_test.go
@@ -0,0 +1,193 @@
+package schema_test
+
+import (
+	"database/sql"
+	"fmt"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"heckel.io/ntfy/v2/db/pg"
+	"heckel.io/ntfy/v2/db/schema"
+	dbtest "heckel.io/ntfy/v2/db/test"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+const testCreateQuery = `CREATE TABLE IF NOT EXISTS things (id TEXT PRIMARY KEY, name TEXT NOT NULL)`
+
+func testCreate(tx *sql.Tx) error {
+	_, err := tx.Exec(testCreateQuery)
+	return err
+}
+
+func openTestPostgres(t *testing.T) *sql.DB {
+	t.Helper()
+	host, err := pg.Open(dbtest.CreateTestPostgresSchema(t))
+	require.Nil(t, err)
+	t.Cleanup(func() { host.DB.Close() })
+	return host.DB
+}
+
+func openTestSQLite(t *testing.T) *sql.DB {
+	t.Helper()
+	d, err := sql.Open("sqlite3", filepath.Join(t.TempDir(), "test.db"))
+	require.Nil(t, err)
+	t.Cleanup(func() { d.Close() })
+	return d
+}
+
+func forEachDialect(t *testing.T, f func(t *testing.T, d *sql.DB, dialect schema.Dialect)) {
+	t.Run("postgres", func(t *testing.T) {
+		f(t, openTestPostgres(t), schema.Postgres)
+	})
+	t.Run("sqlite", func(t *testing.T) {
+		f(t, openTestSQLite(t), schema.SQLite)
+	})
+}
+
+func TestMigrate_FreshCreate(t *testing.T) {
+	forEachDialect(t, func(t *testing.T, d *sql.DB, dialect schema.Dialect) {
+		// A fresh database jumps straight to the target version; migration steps are not consulted
+		require.Nil(t, schema.Migrate(d, dialect, "things", 3, testCreate, nil))
+		_, err := d.Exec(`INSERT INTO things (id, name) VALUES ('a', 'thing a')`)
+		require.Nil(t, err)
+		require.Equal(t, 3, storeVersion(t, d, dialect, "things"))
+		// Idempotent: a second node boots against the migrated schema
+		require.Nil(t, schema.Migrate(d, dialect, "things", 3, testCreate, nil))
+	})
+}
+
+func TestMigrate_AppliesMigrationSteps(t *testing.T) {
+	forEachDialect(t, func(t *testing.T, d *sql.DB, dialect schema.Dialect) {
+		require.Nil(t, schema.Migrate(d, dialect, "things", 1, testCreate, nil))
+		// A newer version of the code migrates 1 -> 3 step by step, in order
+		migrations := map[int]schema.MigrateFunc{
+			1: func(tx *sql.Tx) error {
+				_, err := tx.Exec(`ALTER TABLE things ADD COLUMN color TEXT NOT NULL DEFAULT ''`)
+				return err
+			},
+			2: func(tx *sql.Tx) error {
+				_, err := tx.Exec(`ALTER TABLE things ADD COLUMN size INT NOT NULL DEFAULT 0`)
+				return err
+			},
+		}
+		require.Nil(t, schema.Migrate(d, dialect, "things", 3, testCreate, migrations))
+		_, err := d.Exec(`INSERT INTO things (id, name, color, size) VALUES ('b', 'thing b', 'red', 2)`)
+		require.Nil(t, err)
+		require.Equal(t, 3, storeVersion(t, d, dialect, "things"))
+	})
+}
+
+func TestMigrate_ClosureCarriesConfig(t *testing.T) {
+	// Migrations needing config take it via closure at map-construction time; there is no
+	// params plumbing in the framework itself
+	migrationsFor := func(defaultName string) map[int]schema.MigrateFunc {
+		return map[int]schema.MigrateFunc{
+			1: func(tx *sql.Tx) error {
+				_, err := tx.Exec(fmt.Sprintf(`ALTER TABLE things ADD COLUMN nick TEXT NOT NULL DEFAULT '%s'`, defaultName))
+				return err
+			},
+		}
+	}
+	forEachDialect(t, func(t *testing.T, d *sql.DB, dialect schema.Dialect) {
+		require.Nil(t, schema.Migrate(d, dialect, "things", 1, testCreate, nil))
+		_, err := d.Exec(`INSERT INTO things (id, name) VALUES ('a', 'thing a')`)
+		require.Nil(t, err)
+		require.Nil(t, schema.Migrate(d, dialect, "things", 2, testCreate, migrationsFor("configured-default")))
+		var nick string
+		require.Nil(t, d.QueryRow(`SELECT nick FROM things WHERE id = 'a'`).Scan(&nick))
+		require.Equal(t, "configured-default", nick)
+	})
+}
+
+func TestMigrate_InvalidDialect(t *testing.T) {
+	d := openTestSQLite(t)
+	err := schema.Migrate(d, schema.Dialect(99), "things", 1, testCreate, nil)
+	require.Error(t, err)
+}
+
+func TestMigrate_RefusesFutureVersion(t *testing.T) {
+	forEachDialect(t, func(t *testing.T, d *sql.DB, dialect schema.Dialect) {
+		require.Nil(t, schema.Migrate(d, dialect, "things", 2, testCreate, map[int]schema.MigrateFunc{}))
+		err := schema.Migrate(d, dialect, "things", 1, testCreate, nil)
+		require.Error(t, err)
+	})
+}
+
+func TestMigrate_MissingStepFails(t *testing.T) {
+	forEachDialect(t, func(t *testing.T, d *sql.DB, dialect schema.Dialect) {
+		require.Nil(t, schema.Migrate(d, dialect, "things", 1, testCreate, nil))
+		err := schema.Migrate(d, dialect, "things", 3, testCreate, nil) // No step 1 -> 2 registered
+		require.Error(t, err)
+	})
+}
+
+func TestMigrate_StoresAreIndependent(t *testing.T) {
+	// Postgres only: stores share one database, tracked as rows in schema_version. On SQLite
+	// every store has its own database file, so independence is by file.
+	d := openTestPostgres(t)
+	require.Nil(t, schema.Migrate(d, schema.Postgres, "things", 1, testCreate, nil))
+	require.Nil(t, schema.Migrate(d, schema.Postgres, "gadgets", 4, func(tx *sql.Tx) error {
+		_, err := tx.Exec(`CREATE TABLE IF NOT EXISTS gadgets (id TEXT PRIMARY KEY)`)
+		return err
+	}, nil))
+	require.Equal(t, 1, storeVersion(t, d, schema.Postgres, "things"))
+	require.Equal(t, 4, storeVersion(t, d, schema.Postgres, "gadgets"))
+}
+
+func TestMigrate_SQLiteReadsExistingSchemaVersionTable(t *testing.T) {
+	// Existing ntfy SQLite databases (message, user, webpush) track their version in a
+	// schemaVersion (id, version) table keyed by id = 1; the framework uses that table as-is
+	// on SQLite, so existing databases migrate without any adoption step
+	d := openTestSQLite(t)
+	_, err := d.Exec(testCreateQuery)
+	require.Nil(t, err)
+	_, err = d.Exec(`CREATE TABLE schemaVersion (id INT PRIMARY KEY, version INT NOT NULL)`)
+	require.Nil(t, err)
+	_, err = d.Exec(`INSERT INTO schemaVersion VALUES (1, 1)`)
+	require.Nil(t, err)
+	migrations := map[int]schema.MigrateFunc{
+		1: func(tx *sql.Tx) error {
+			_, err := tx.Exec(`ALTER TABLE things ADD COLUMN color TEXT NOT NULL DEFAULT ''`)
+			return err
+		},
+	}
+	require.Nil(t, schema.Migrate(d, schema.SQLite, "things", 2, testCreate, migrations))
+	_, err = d.Exec(`INSERT INTO things (id, name, color) VALUES ('a', 'thing a', 'red')`)
+	require.Nil(t, err)
+	require.Equal(t, 2, storeVersion(t, d, schema.SQLite, "things"))
+}
+
+func TestMigrate_ConcurrentFreshCreate(t *testing.T) {
+	// Postgres only: concurrent cold-boots must not race on DDL (CREATE TABLE IF NOT EXISTS is
+	// not atomic); Migrate serializes via an advisory lock. SQLite has a single writer.
+	schemaDSN := dbtest.CreateTestPostgresSchema(t)
+	const n = 8
+	errs := make(chan error, n)
+	for i := 0; i < n; i++ {
+		go func() {
+			host, err := pg.Open(schemaDSN)
+			if err != nil {
+				errs <- err
+				return
+			}
+			defer host.DB.Close()
+			errs <- schema.Migrate(host.DB, schema.Postgres, "things", 1, testCreate, nil)
+		}()
+	}
+	for i := 0; i < n; i++ {
+		require.Nil(t, <-errs)
+	}
+}
+
+func storeVersion(t *testing.T, d *sql.DB, dialect schema.Dialect, store string) int {
+	t.Helper()
+	var version int
+	if dialect == schema.Postgres {
+		require.Nil(t, d.QueryRow(`SELECT version FROM schema_version WHERE store = $1`, store).Scan(&version), fmt.Sprintf("store %s", store))
+	} else {
+		require.Nil(t, d.QueryRow(`SELECT version FROM schemaVersion WHERE id = 1`).Scan(&version), fmt.Sprintf("store %s", store))
+	}
+	return version
+}
diff --git a/webpush/store_sqlite.go b/webpush/store_sqlite.go
index 7677f1ce..e03a43b1 100644
--- a/webpush/store_sqlite.go
+++ b/webpush/store_sqlite.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 
 	_ "github.com/mattn/go-sqlite3" // SQLite driver
-
 	"heckel.io/ntfy/v2/db"
 )