-- Migration 090: Add modification tracking columns
--
-- Tracks when records were last modified and by which task.
-- Enables debugging, auditing, and understanding data freshness.
--
-- Columns added:
--   last_modified_at      - When the record was last modified by a task
--   last_modified_by_task - Which task role modified it (e.g., 'product_refresh')
--   last_modified_task_id - The specific task ID that modified it

-- ============================================================
-- dispensaries table
-- ============================================================
ALTER TABLE dispensaries
ADD COLUMN IF NOT EXISTS last_modified_at TIMESTAMPTZ;

ALTER TABLE dispensaries
ADD COLUMN IF NOT EXISTS last_modified_by_task VARCHAR(50);

ALTER TABLE dispensaries
ADD COLUMN IF NOT EXISTS last_modified_task_id INTEGER;

-- Index for querying recently modified records
CREATE INDEX IF NOT EXISTS idx_dispensaries_last_modified
  ON dispensaries(last_modified_at DESC)
  WHERE last_modified_at IS NOT NULL;

-- Index for querying by task type
CREATE INDEX IF NOT EXISTS idx_dispensaries_modified_by_task
  ON dispensaries(last_modified_by_task)
  WHERE last_modified_by_task IS NOT NULL;

COMMENT ON COLUMN dispensaries.last_modified_at IS 'Timestamp when this record was last modified by a task';
COMMENT ON COLUMN dispensaries.last_modified_by_task IS 'Task role that last modified this record (e.g., store_discovery_state, entry_point_discovery)';
COMMENT ON COLUMN dispensaries.last_modified_task_id IS 'ID of the worker_tasks record that last modified this';

-- ============================================================
-- store_products table
-- ============================================================
ALTER TABLE store_products
ADD COLUMN IF NOT EXISTS last_modified_at TIMESTAMPTZ;

ALTER TABLE store_products
ADD COLUMN IF NOT EXISTS last_modified_by_task VARCHAR(50);

ALTER TABLE store_products
ADD COLUMN IF NOT EXISTS last_modified_task_id INTEGER;

-- Index for querying recently modified products
CREATE INDEX IF NOT EXISTS idx_store_products_last_modified
  ON store_products(last_modified_at DESC)
  WHERE last_modified_at IS NOT NULL;

-- Index for querying by task type
CREATE INDEX IF NOT EXISTS idx_store_products_modified_by_task
  ON store_products(last_modified_by_task)
  WHERE last_modified_by_task IS NOT NULL;

-- Composite index for finding products modified by a specific task
CREATE INDEX IF NOT EXISTS idx_store_products_task_modified
  ON store_products(dispensary_id, last_modified_at DESC)
  WHERE last_modified_at IS NOT NULL;

COMMENT ON COLUMN store_products.last_modified_at IS 'Timestamp when this record was last modified by a task';
COMMENT ON COLUMN store_products.last_modified_by_task IS 'Task role that last modified this record (e.g., product_refresh, product_discovery)';
COMMENT ON COLUMN store_products.last_modified_task_id IS 'ID of the worker_tasks record that last modified this';