ALTER TABLE pieces ADD COLUMN interaction_text TEXT NOT NULL DEFAULT '';
ALTER TABLE piece_usages ADD COLUMN interaction_snapshot TEXT NOT NULL DEFAULT '';

CREATE TABLE live_show_timer_runs (
  id TEXT PRIMARY KEY,
  show_id TEXT NOT NULL REFERENCES shows(id) ON DELETE CASCADE,
  started_at_utc TEXT NOT NULL,
  ended_at_utc TEXT,
  CHECK (ended_at_utc IS NULL OR ended_at_utc >= started_at_utc)
);

CREATE UNIQUE INDEX idx_one_open_show_timer_run
ON live_show_timer_runs(show_id)
WHERE ended_at_utc IS NULL;

CREATE INDEX idx_live_show_timer_runs_show
ON live_show_timer_runs(show_id, started_at_utc);

INSERT INTO live_show_timer_runs (id, show_id, started_at_utc, ended_at_utc)
SELECT 'migrated-' || id, show_id, started_at_utc, ended_at_utc
FROM live_usage_runs;