-- Odin Phase 2a: assistant turns carry structured metadata (tool-call trace,
-- later full content blocks). `content` stays the plain-text display
-- projection; `content_json` holds the structured form. Anticipated by the
-- Phase-2 design notes (2026-06-08).

-- AlterTable
ALTER TABLE `ai_chat_messages` ADD COLUMN `content_json` LONGTEXT NULL AFTER `content`;