CREATE TABLE IF NOT EXISTS push_devices (
    id BIGSERIAL PRIMARY KEY,
    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    session_id INTEGER NOT NULL REFERENCES sessions(id) ON DELETE CASCADE,
    device_id UUID NOT NULL UNIQUE,
    token TEXT NOT NULL UNIQUE CHECK (length(token) BETWEEN 20 AND 4096),
    platform VARCHAR(16) NOT NULL CHECK (platform = 'android'),
    app_version VARCHAR(32) NOT NULL DEFAULT '',
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    last_seen_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);
CREATE INDEX IF NOT EXISTS idx_push_devices_user ON push_devices(user_id);
CREATE INDEX IF NOT EXISTS idx_push_devices_session ON push_devices(session_id);