`okf build` recovers a PDF's boundaries from the shape of its page text and
never opens the file's own `/Outlines` bookmark tree. On a 701-page process
code whose publisher also ships a NISO-STS structure for it, measured outside
this repository and reproduced here exactly: the shipped default finds 1967 of
2761 titled sections, 0 of its 28 chapters, and 794 of 794 misses have their
heading text PRESENT in the extracted text. The line was read; the boundary
was never opened. The same file's bookmark tree matches 2761 of 2761 of those
titles exactly after normalisation.
`--pdf-outline`, OFF, cuts a PDF at the boundaries its tree declares.
boundaries 1967 of 2761 -> 2759 of 2761 (gate was 2700)
depth 1 0 of 28 -> 28 of 28
titles identical to source -- -> 2761 of 2761
false positives 163 of 2182 -> 3 of 2762
directories with two files 132 of 2050 -> 2 of 2738
front-matter concepts 72 of 2182 -> 2 of 2762
consumption fasit present 4 of 7 -> 7 of 7
hit@1 / hit@8 / hit@50 1/6 2/6 4/6 -> 3/6 5/6 6/6
It is a SEGMENTATION arm, not a reader option: the extracted text is byte for
byte the same either way. A PDF with no tree builds byte-identically with the
flag on -- `diff -r` empty across the pre-change tree, the arm off and the arm
on. An unresolvable `/Dest` is dropped and COUNTED, never fabricated into a
boundary and never a refusal of the file.
The bridge from (page, y) to a line index is the whole risk, so both routes
are measured. `extract_text_lines` splits lines identically to `extract_text`
on 701 of 701 pages, and is CHECKED per page rather than assumed. The y route
and the title route disagree on 0 of 2762 nodes, flat from a 0pt tolerance to
8pt and collapsing at 12pt, so the rule ships with no tolerance constant. The
naive "nearest line" rule was wrong on 1840 of 2762, one line early every time.
The orphan check is not applied to a bookmark mark: it asks whether anything
stands under a candidate's first line, which is the right question for a
heuristic's guess and the wrong one for a publisher's declaration. 683 of 2762
marks are container sections; applying it scores 2079 instead of 2759.
No new dependency and no second parse of the pages: `pdfminer.six` already
ships under `pdfplumber` in `[extract]`. 119.22s -> 183.31s wall, peak RSS
3252 -> 3251 MiB. The default does not move; 1 of the 8 reference PDFs carries
a usable tree at all.
`.pdf` also gains its `_EVIDENCE` row, as `measured` -- it was the row with the
most measurement behind it and no entry in the table.
Report: docs/2026-09-10-k3-runde12-pdf-outlines.md
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
