# Task: Classify Ventilation Status (Raw Tables)

All derived shortcut tables have been removed from the task database.
You must derive ventilation status from source clinical tables.

Classify ventilation status from charting data and group consecutive
observations into ventilation episodes for each ICU stay, following
the MIT-LCP mimic-code ventilation concept definition.

Categories (in priority order): Tracheostomy, InvasiveVent,
NonInvasiveVent, HFNC, SupplementalOxygen, None.

Exclude single-observation episodes (starttime = endtime) and
observations with no classification.

`ventilation_seq` = ROW_NUMBER() within each stay, ordered by starttime.

Output a CSV file to `{output_path}` with these exact columns:
stay_id, ventilation_seq, starttime, endtime, ventilation_status

One row per ventilation episode. Multiple rows per ICU stay.
