-- Exam-prep practices: one row per practice, attached to an exam-prep lesson only; reuses public.question_sets / questions.
CREATE TABLE exam_prep.lesson_practices (
    id BIGSERIAL PRIMARY KEY,
    unit_module_lesson_id BIGINT NOT NULL REFERENCES exam_prep.unit_module_lessons (id) ON DELETE CASCADE,
    title VARCHAR(255) NOT NULL,
    story_description TEXT,
    story_image TEXT,
    persona_id BIGINT REFERENCES users (id) ON DELETE SET NULL,
    question_set_id BIGINT NOT NULL REFERENCES question_sets (id) ON DELETE RESTRICT,
    quick_tips TEXT,
    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMPTZ
);

CREATE INDEX idx_exam_prep_lesson_practices_lesson_id ON exam_prep.lesson_practices (unit_module_lesson_id);
CREATE INDEX idx_exam_prep_lesson_practices_question_set_id ON exam_prep.lesson_practices (question_set_id);
CREATE INDEX idx_exam_prep_lesson_practices_lesson_created ON exam_prep.lesson_practices (unit_module_lesson_id, created_at DESC);