Tell a caller when a readable page still hides unread visual content

[silverstein]

The gap

convert_pdf_to_markdown already reports VECTOR_CONTENT_NOT_INTERPRETED in its coverage gaps — in prose. Nothing structured carried it, so a vision-capable host reading the response saw pages_needing_vision: [] and was never told there was anything to look at.

Those two outputs are not in conflict, and I first misread them as such. pages_needing_vision answers "can this page be read at all without vision?" (path_segment_count >= 1000 && textLength < 30). Shannon page 40 is mostly text, so it correctly stays out.

What had no signal at all is the middle case: a page that reads fine and still contains something the converter did not interpret. Shannon's Table I is exactly that — five small plots nobody is ever told about.

What this adds

pages_with_unread_visual_content republishes the gap codes that page already reported, in a field a caller can act on. It forms no new opinion about the content, carries no geometry it cannot derive, and never claims the thing is a chart.

A separate field rather than a new reason inside pages_needing_vision, because that field means "unreadable without vision" and these pages are readable — saying otherwise would be a false statement made to fix a missing one, and it feeds the documentKind classifier.

Population — measured, and thin

Across the first three pages of 35 fixture documents plus the Shannon paper: exactly one document, one page.

Worth stating plainly rather than burying. But the fixture corpus is almost entirely synthetic — forms and small generated PDFs built to exercise code paths — so it contains nearly nothing resembling the documents where this matters (papers with figures, reports with charts). The corpus cannot really answer the question. The failure is demonstrated; the breadth is not.

I'd rather hand you that than a number dressed up to justify the change. If you'd sooner not carry a field on this evidence, closing it is a reasonable call and I won't re-litigate it.

Verification

160 tests green across the five affected suites, including a new live test derived from the real document. Tool contract digest re-pinned — the structured output changed; no tool name, description, input schema, or annotation did. Layout oracle regenerated: source-identity digests only, no scored case changed. Share mirror byte-identical across all three server files.

🤖 Generated with Claude Code