Reads and writes are fully cut over to the normalized copilot_messages table
(verified in production: no writes to the column in 24h, recently-active chats
have empty JSONB while copilot_messages holds the transcript). Drop the dead
column via drizzle migration 0225 and re-type CopilotChatDetailRow.messages as
an assembled (non-column) field.
Deploy notes: reconcile any chats where the JSONB still leads copilot_messages
before applying, and pg_repack copilot_chats afterward to reclaim the ~5.7GB
TOAST storage (DROP COLUMN is metadata-only).
Waleed
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