{
    "action": "tool_call",
    "reasoning": "The evidence section holds no results for this turn, so I'll re-ground the column classification in a single profile query. It gets exact distinct counts and ranges for the key, the classifiers and the numeric columns.",
    "tool": "query_sql",
    "args": {
        "sql": "SELECT COUNT(*) AS n, COUNT(DISTINCT user_id) AS d_user, MIN(user_id) AS min_user, MAX(user_id) AS max_user, COUNT(DISTINCT gender) AS d_gender, COUNT(DISTINCT occupation_type) AS d_occ, COUNT(DISTINCT chronotype) AS d_chrono, COUNT(DISTINCT primary_bedtime_app) AS d_app, COUNT(DISTINCT sleep_debt_category) AS d_debt, COUNT(DISTINCT blue_light_filter_active) AS d_blue, MIN(age) AS age_min, MAX(age) AS age_max, MIN(bedtime_phone_minutes) AS phone_min, MAX(bedtime_phone_minutes) AS phone_max, MIN(screen_brightness_pct) AS bright_min, MAX(screen_brightness_pct) AS bright_max, MIN(caffeine_post_5pm_mg) AS caf_min, MAX(caffeine_post_5pm_mg) AS caf_max, MIN(physical_activity_min) AS act_min, MAX(physical_activity_min) AS act_max, MIN(sleep_latency_min) AS lat_min, MAX(sleep_latency_min) AS lat_max, MIN(total_sleep_hours) AS sleep_min, MAX(total_sleep_hours) AS sleep_max, MIN(deep_sleep_pct) AS deep_min, MAX(deep_sleep_pct) AS deep_max, MIN(rem_sleep_pct) AS rem_min, MAX(rem_sleep_pct) AS rem_max, MIN(morning_alarm_snoozes) AS snz_min, MAX(morning_alarm_snoozes) AS snz_max, MIN(next_day_fatigue_score) AS fat_min, MAX(next_day_fatigue_score) AS fat_max, MIN(_ingestion_timestamp) AS ing_min, MAX(_ingestion_timestamp) AS ing_max FROM raw.bedtime_screentime_sleep_debt",
        "purpose": "Verify key uniqueness, classifier cardinalities and numeric ranges to classify all columns by role",
        "source": "raw"
    }
}