A tagged/structured PDF carries a logical structure tree
(/Root/StructTreeRoot, /MarkInfo) that maps marked page content to
semantic elements via MCIDs. When --force-ocr rasterizes pages or
--redo-ocr rewrites the text layer, those MCIDs are destroyed or
renumbered and the tree is left dangling. We cannot rebuild it to match
the new text, so discard it for force/redo modes, following the same
pattern as the thumbnail and search-index discards. --skip-text leaves
text pages untouched, so their structure is preserved.
Also broaden the default-mode "looks born-digital" stop signal to fire
on /StructTreeRoot, not just /MarkInfo/Marked, so structure-tree-only
PDFs are no longer silently OCR'd. The existing --tagged-pdf-mode ignore
escape hatch is unchanged.
Expose Ghostscript's -dJPEGQ and image downsampling switches as
advanced, plugin-scoped options for tuning PDF/A output, without
polluting the central OcrOptions registry. The optimizer's existing
--jpeg-quality remains the recommended JPEG quality control.
- GhostscriptOptions gains jpeg_quality and jpeg_maxdpi fields and CLI
args (advanced help text). jpeg_quality=0 is honored as Ghostscript's
maximum compression rather than being silently coerced to the default.
- _exec.ghostscript.generate_pdfa() forwards both values; when
jpeg_maxdpi is set, downsample threshold is pinned at 1.0.
- _get_plugin_options falls back to extra_attrs for namespaced fields
so plugins can own their options without registering them centrally.
- Documentation explains the rationale: Ghostscript is the legacy path
(pypdfium + verapdf is preferred in v17+), the optimizer is the
supported file-size lever, and lowering quality is almost always a
better trade than downsampling.
James R. Barlow