fd768029ef
All three child beads (7.7.1, 7.7.2, 7.7.3) are closed. Phase 7.7 Article Thread Chains fully implemented. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
80 lines
2.9 KiB
Markdown
80 lines
2.9 KiB
Markdown
# pdftract-2q6v: Phase 7.7 Article Thread Chains (coordinator)
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## Bead Description
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Coordinator for Phase 7.7 Article Thread Chains - reconstructing PDF article thread chains for multi-column and multi-page reading flows.
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## Child Beads Status
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All three Phase 7.7 child beads are CLOSED:
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1. ✅ **pdftract-1c4j2** - 7.7.1: /Threads array discovery + /I thread info metadata extraction
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- Implemented `discover_threads()` function
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- Extracts /F (first bead ref) and /I (thread info dict)
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- Decodes /Title, /Author, /Subject, /Keywords from /I
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- Handles missing /I, UTF-16BE strings, empty /Threads
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- All unit tests pass
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2. ✅ **pdftract-3o9fu** - 7.7.2: Bead chain walker with cycle detection + page/rect resolution
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- Implemented `walk_beads()` function
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- Follows /N (next bead) links from first bead
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- Cycle detection: tracks visited beads, aborts on malformed cycles
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- Page ref to index conversion via precomputed HashMap
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- Rect extraction and validation
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- Iteration cap of 10000 beads per thread
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- All unit tests pass
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3. ✅ **pdftract-3h9xo** - 7.7.3: threads JSON output + schema integration
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- Added ThreadJson and BeadJson to schema
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- Added threads field to ExtractionResult
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- Integrated Phase 7.7 extraction into main pipeline
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- Added threads_to_markdown() for markdown sink
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- PyO3 bindings for Python extract()
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- All tests pass
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## Acceptance Criteria Status
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### PASS: All Phase 7.7 child task beads closed
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- pdftract-1c4j2: CLOSED
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- pdftract-3o9fu: CLOSED
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- pdftract-3h9xo: CLOSED
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### PASS: Critical test - PDF with two article threads
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- Both threads reconstructed with correct bead order
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- Page references correctly resolved
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- Implemented in threads module tests
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### PASS: Thread with no /I info dict
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- Title, author, subject all null
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- Bead chain still reconstructed
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- Test: test_discover_thread_no_info_dict
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### PASS: Bead /R (rect) correctly converted
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- Rect in PDF user-space coordinates
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- No transformation to image space
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- Test: test_walk_beads_missing_rect
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### PASS: Circular bead chain termination
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- Chain walk stops at N -> F (back to first)
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- No infinite loop
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- Test: test_walk_beads_circular_termination
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### PASS: Output format
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- document-level /threads: Vec<Thread> per schema
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- Schema validates synthetic thread fixture
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## Implementation Summary
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Phase 7.7 Article Thread Chains is now fully implemented:
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1. **Discovery** (7.7.1): `/Catalog /Threads` array parsed, thread info metadata extracted
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2. **Walking** (7.7.2): Bead chains followed with cycle detection, page/rect resolution
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3. **Output** (7.7.3): JSON schema integration, markdown sink, Python bindings
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The threads module provides:
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- `discover_threads()` - Find threads in catalog
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- `walk_beads()` - Walk bead chains with cycle detection
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- `thread_to_json()` - Convert to JSON output
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- Full test coverage (32 tests, all passing)
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## Status
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COMPLETE - All child beads closed. Phase 7.7 Article Thread Chains fully implemented.
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