-- ==============================================================================
-- Stage 1 Correction & Upgrade: Watch-Time Accuracy Metrics
-- Non-destructive migration: Adds new tracking metrics while preserving all data.
-- ==============================================================================

ALTER TABLE watch_sessions 
ADD COLUMN IF NOT EXISTS foreground_watch_seconds NUMERIC NOT NULL DEFAULT 0,
ADD COLUMN IF NOT EXISTS pause_seconds NUMERIC NOT NULL DEFAULT 0,
ADD COLUMN IF NOT EXISTS tab_inactive_seconds NUMERIC NOT NULL DEFAULT 0,
ADD COLUMN IF NOT EXISTS muted_seconds NUMERIC NOT NULL DEFAULT 0,
ADD COLUMN IF NOT EXISTS content_watched_seconds NUMERIC NOT NULL DEFAULT 0,
ADD COLUMN IF NOT EXISTS content_intervals JSONB NOT NULL DEFAULT '[]'::jsonb;

-- Add index on sessions for fast query performance
CREATE INDEX IF NOT EXISTS idx_sessions_status ON watch_sessions(status);