The tier-0 classifier escalated any page with raster-image coverage >=0.80 to
the OCR tier regardless of its text layer. On OHR-Bench this drove ~45% of all
OCR escalations: clean born-digital pages dominated by a figure, and scanned
pages that already carry a usable OCR text layer -- re-OCR adds nothing for
either, but each one was routed to the paid tier-3 OCR.
Route on the text signals only (near-empty or junk-quality layer). Image
coverage is still computed and still raises the `image_heavy` diagnostic flag,
but no longer routes. True scans with no/garbage text continue to escalate via
the empty-text and quality signals, so genuine OCR needs are unaffected.
Trade-off: image-only content on an otherwise-clean page (handwriting, stamps,
text inside figures) is no longer force-routed to OCR. This was previously
intentional; the escalation cost outweighed the benefit for RAG indexing.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
