choplin/explainer-studio/epub-explainer-epub-extract

Extract one EPUB spine range

The parent [[epub-explainer-summarize]] supplies absolute paths to contiguous epub/spine/item-*.json files, epub/locators.json, and one output path under extract/. Read only those inputs.

Write structured material, not a finished report:

1. ## Coverage — spine indices/resources and first/last canonical locators.
2. ## Headings — one row per source heading:

[loc:<canonical>] L<level> | <source title>.

1. ## Material — faithful paragraphs, lists, tables, notes, ruby readings, and

figure/SVG references grouped under their source headings.

1. ## Boundary — whether the range starts or ends mid-division and the exact

locator needed by the adjacent worker.

Treat each block's source_xhtml as the fidelity authority when its Markdown view lost structure. Preserve facts and semantics; compress repetition but do not write interpretive conclusions. Return only the output path and one-line boundary state.