defmodule CMDCMemoryPg.Repo.Migrations.CreateCmdcCheckpoints do
  use Ecto.Migration

  def change do
    create table(:cmdc_checkpoints, primary_key: false) do
      add :session_id, :string, null: false, size: 255
      add :checkpoint_id, :string, null: false, size: 64
      # snapshot 走 :erlang.term_to_binary(snap, [:compressed]) → bytea
      # 避开 jsonb 对 atom / Message struct 的序列化痛点
      add :snapshot, :binary, null: false
      add :label, :string, size: 128
      add :metadata, :map, null: false, default: %{}
      add :saved_at, :utc_datetime_usec, null: false
    end

    create index(:cmdc_checkpoints, [:session_id])
    create index(:cmdc_checkpoints, [:saved_at])
    create unique_index(:cmdc_checkpoints, [:session_id, :checkpoint_id])
  end
end