David debugged: Lecture notes prefetch state contradiction on failed run

An agent reported that prefetch metrics showed attempted=6, completed=6, failed=0 while the workspace generation had failed, and attributed the failure to missing PDF page insertions. David caught the contradiction:

I don't believe you. go and see what the primary

When the agent then said the files were actually page-type topics (not PDFs), David called out the incoherence:

yes and how is there meant to be a insert pdf pages requirement if the file type is a page??? you said it failed due to not inserting the pdf pages and you even showed me what pages it was expecting. but then now you say oh no they were actually pages, not pdfs. youre not being coherent

The investigation ultimately found that prefetch_state='failed' had been overwritten with the downstream lecture-generation failure reason, masking that prefetch had actually completed — a misleading state field. David's refusal to accept the surface-level answer was what uncovered the real contradiction between prefetch_metrics and prefetch_state.