Support non-canonical/peripheral books

Start with usjBookExtractor.ts, bookTokenizer.ts, and useInterlinearizerBookData.ts, then review ScriptureRef and the named fixture builders. Run usjBookExtractor.test.ts and bookTokenizer.test.ts to understand the current verse assumptions; completion depends on defining the open questions and on platform support for opening and navigating extra-material books.

Summary

The interlinearizer assumes every book has real chapters and verses.

Paratext's 15 non-canonical/peripheral book codes don't: XXA–XXG, FRT, BAK, OTH, INT, CNC, GLO, TDX, NDX. They're paragraph-structured, not verse-structured.

Today, opening one of these books doesn't error. It silently tokenizes to zero segments and renders a blank view — no message explains why.

paranext-core support

• Canon.nonCanonicalIds / Canon.isExtraMaterial model these 15 codes explicitly.
• Storage, project settings, and VerseRef validity treat them uniformly with canonical books. VerseRef.internalValid skips chapter/verse bounds checking for them entirely.
• Some platform UI (Find, the book/chapter quick-nav control, Manage Books) deliberately excludes or special-cases them, since they have no real chapter/verse structure to browse or search by.

So paranext-core has the vocabulary and partial precedent. This extension has none of it.

What core would need to add

• A way to open/view/edit extra-material content at all. The platform's own Find feature excludes these books today for exactly this reason (tracked as PT-4414: "drop this exclusion once extra material can be opened and addressed"). Until that lands, there's no host capability for this extension to build on.
• A paragraph-structured content API. platformScripture.USJ_Book is the only USJ access point this extension uses, and it's requested through a chapter/verse-shaped reference. Peripheral books need a way to fetch and navigate their content that doesn't route through chapter/verse at all.
• Chapter/verse quick-nav support, or an equivalent. The platform's book-chapter control currently drops all 15 peripheral ids because "it cannot browse to them." Some paragraph-level navigation primitive would need to take that spot.
• Optionality for verse/chapter in the shared scripture-reference types, so a peripheral book can be the active reference without a meaningless chapter/verse pair attached.

Current gaps

No awareness of the distinction

• Zero references anywhere in the codebase to Canon.isCanonical, Canon.isExtraMaterial, Canon.nonCanonicalIds, or any of the 15 codes.
• Canon is imported in exactly two places, both display-only (bookIdToEnglishName) — never for filtering.

Tokenizer/segmentation pipeline assumes verse structure

• usjBookExtractor.ts only accumulates text into state.currentVerse, which is set only by a \c/\v node handler. A peripheral book has neither, so every character of body text is silently discarded.
• bookTokenizer.ts then maps zero verses to zero segments. No error is raised.
• useInterlinearizerBookData.ts only checks for a missing USJ book, not one that loaded but tokenized to nothing. Result: a blank view, indistinguishable from "this book has no analyzable text."
• ScriptureRef declares chapter/verse as non-optional. There's no way to represent "this paragraph belongs to no chapter/verse."
• The alignment model's documented default — one segment per verse — inherits the same assumption.

No book-selection UI to gate or allow this

• The extension has no book picker of its own. Project creation only collects name, description, and analysis languages.
• Book/chapter/verse is entirely driven by the platform's shared scroll-group reference. Whatever restriction (or lack of one) the platform's navigation control applies is the only gate that exists today.

Test-fixture coverage: zero

• No test, fixture, or comment anywhere in the suite references any of the 15 codes.
• Every shared book-fixture builder (GEN_1_1_BOOK, defaultScrRef, makeRawBook, makeVerseBook) is hardcoded to, or defaults to, canonical verse-structured books.
• makeSegment actively throws unless its sid parses as "<BOOK> <chapter>:<verse>". Building a segment fixture for a peripheral book is structurally impossible with this helper today.
• Two tests exercise "no verse markers" generically (usjBookExtractor.test.ts, bookTokenizer.test.ts), both using book code GEN. Neither is framed around, or asserts anything about, the peripheral-book case.

Non-goals

• Deuterocanon/apocrypha books (TOB, WIS, 1MA, etc.) are full canon members in paranext-core's model already. Out of scope here.

Open questions

• What should the UI show when a peripheral book is the active scripture reference: a blank interlinearizer, or an explicit "not supported" message (mirroring the platform's own Find-feature pattern)?
• Does paragraph-structured content need its own segment-identity scheme, or can it reuse a synthetic verse-like key?
• Should this wait on the platform's own extra-material viewing/editing support? The interlinearizer can't display these books meaningfully until the platform can.

Related: #129, #230 (alignment format's one-segment-per-verse default shares this gap).

Size: L — touches parsing, tokenization, segmentation, and every verse-keyed data structure.