Reconstruct captioned tables from segmented header rules

[silverstein]

Outcome

Recover bounded multi-column Markdown tables when PDF ruling geometry explicitly defines the header and column intervals. Continuation pages must independently provide their own header; no cross-page stitching or inferred group values.

Safety and scope

• Require a TABLE caption, aligned outer rules, contiguous header segments, unique source assignment and complete numeric rows.
• Reject spanning or missing cells, competing rules, overprint, boundary crossings, missing headers and incomplete source evidence.
• Preserve source/share parity, existing fallback warnings and exact source bindings; renderer contract advances to 1.21.0.

Verification

• Stonebook macOS arm64, Node 26.5.0, one worker: 220 distinct targeted tests passed, 6 artifact-backed skips, zero failures.
• Independent review passed exact head a6798fa.
• Real MCP replay of the original public CDC PDF reconstructs two six-column tables with 30 and 25 numeric data rows. All four previously frozen sampled rows and visible footnote markers are retained.
• Original source and first-run failures remain preserved. The PDF is now a development regression, not an untouched holdout. Overall conversion remains partial for unrelated vector, link and footnote topology limitations.

This is source integration, not a release or a comparative benchmark claim. Full CI remains the integration gate.