After deeper headless probe (manual _popRr inject to force vast mode),
VAST SDK loaded but never showed ad. Direct curl to
/api/users/<vast_spot> returns empty <VAST version="3.0"></VAST> — ASG
no-fill response. Popunder spot at same time returns full creative
config (creative_id 83660 etc). Diagnosis: ASG admin spot config issue
(type wrong / pending / no creative / budget / etc), not our code.
Includes diagnostic curl recipe so future "VAST never shows" can be
distinguished from code bugs in seconds.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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