diff --git a/ai/internal/rag/store.go b/ai/internal/rag/store.go
index 6328afd..bafaeec 100644
--- a/ai/internal/rag/store.go
+++ b/ai/internal/rag/store.go
@@ -67,7 +67,9 @@ CREATE TABLE IF NOT EXISTS ai.hitl_messages (
   decided_by  text,
   result      jsonb,
   created_at  timestamptz NOT NULL DEFAULT now()
-);`
+);
+-- additive migrations (CREATE TABLE IF NOT EXISTS leaves existing tables untouched; seen 2026-10-08 on the AI VM)
+ALTER TABLE ai.hitl_messages ADD COLUMN IF NOT EXISTS diagnosis jsonb NOT NULL DEFAULT '{}'::jsonb;`
 
 func New(ctx context.Context, dsn string) (*Store, error) {
 	pool, err := pgxpool.New(ctx, dsn)