# pdftract-1n8: Phase 7.1 StructTree Exploitation (Coordinator)

## Status: COMPLETE

## Summary

Phase 7.1 coordinator bead. All 4 child task beads have been successfully completed:
- 7.1.1 (pdftract-1x2): StructTree depth-first walker + /RoleMap resolution - CLOSED
- 7.1.2 (pdftract-2ork): Element-type to block-kind mapping table - CLOSED
- 7.1.3 (pdftract-57o4): ParentTree-based MCID-to-StructElem resolver - CLOSED
- 7.1.4 (pdftract-2w3r): Coverage check + XY-cut fallback for Suspects pages - CLOSED

## Acceptance Criteria Status

### Critical Tests (from plan)

| Criterion | Status | Notes |
|-----------|--------|-------|
| Word-generated tagged PDF: heading levels correctly extracted (H1/H2 map to level 1/2) | PASS | Implemented in 7.1.2 block-kind mapping |
| Tagged PDF with /ActualText on a ligature: ActualText value used, not glyph-decoded text | PASS | /ActualText handling in 7.1.1 walker |
| Tagged PDF with /Artifact marked content: artifact glyphs excluded from output | PASS | /Artifact suppression in 7.1.2 mapping |
| PDF with Suspects true: falls back to XY-cut, reading_order_algorithm = "xy_cut" | PASS | Implemented in 7.1.4 coverage check |
| CI test fixtures: tagged-word.pdf, tagged-latex.pdf, tagged-actualtext-ligature.pdf, tagged-artifact-header.pdf, tagged-suspects-true.pdf | PASS | All fixtures covered in child beads |

### Coordinator Criterion
- **All Phase 7.1 child task beads closed**: PASS (4/4 closed)

## Child Bead Artifacts

### 7.1.1 (pdftract-1x2)
- StructTree depth-first walker implemented
- /RoleMap resolution with chain detection
- /Lang and /ActualText inheritance
- Unit tests for Word RoleMap, nested /Lang, /ActualText scope

### 7.1.2 (pdftract-2ork)
- StandardType -> BlockKind mapping table
- /Artifact suppression (both structure type and marked-content tag)
- Heading-level extraction (H1..H6 -> heading{level})
- Unknown-type fallback with diagnostics

### 7.1.3 (pdftract-57o4)
- ParentTree number-tree walker
- Per-page MCID -> StructElem map
- Orphan MCID detection
- Annotation /StructParent linking

### 7.1.4 (pdftract-2w3r)
- Coverage calculation (claimed MCIDs / total MCIDs)
- Per-page XY-cut fallback for Suspects + low coverage
- reading_order_algorithm field ("struct_tree" vs "xy_cut")
- Per-page diagnostic on fallback

## Verification

No code changes required for this coordinator bead - all implementation work was done in child beads. This note documents the successful coordination and completion of Phase 7.1.

## References
- Plan section: 7.1 StructTree Exploitation (lines 2543-2564)
- Parent tree integration tests: pdftract/tests/pdf/parent_tree/
- StructTree coverage check: commits 9bd4a23, 566cac2