[chortya]

Contribution pause

The maintainer lifted the pause and invited split PRs in #286.

• The change is scoped to one feature (a per-book language for read-aloud voices and hyphenation). Stacked on feat: EPUB text alignment and hyphenation settings (refs #286) #302 (alignment/hyphenation, which adds the device-language fallback this builds on). Only the three commits after feat: EPUB text alignment and hyphenation settings (refs #286) #302 belong to this PR.
• Compatible with the provider-module refactor: reader-only; the per-book store is cleared on logout with the other account-owned reader state.
• Tests and manual-validation status are documented.
• No credentials, cookies, API keys, private server URLs, or generated local data are included.

Summary

Read-aloud only offers voices for the EPUB's declared language. Books with a wrong or missing dc:language (common in converted files) therefore got the wrong voice list, e.g. only Dutch voices for an English book, and the wrong hyphenation patterns.

• In-book options → This book → Book language: Auto (shows the source: book or device) or any installed language, chosen from a dialog with a lazy list.
• An override goes to the EPUB navigator (language, for hyphenation) and the read-aloud navigator (AndroidTtsPreferences.language, which selects the voice list). Both apply live, even while speaking. A change made while read-aloud is still preparing is applied once its navigator exists.
• Readium only injects language into documents whose <html> declares none, so the reader's existing current-document bridge also sets an override on <html>/<body> (lang and xml:lang) and restores the publisher's values on Auto.
• In Auto, a declared book language is left to Readium (so per-element xml:lang still works), and read-aloud keeps Readium's own choice.
• Remembered per book (readium_epub_book_languages, keyed by reader key, not written in Preview, cleared on logout).

Verification

• ./gradlew :app:testDebugUnitTest — 961/961 pass (new EpubBookLanguageTest: resolution order, navigator/TTS language rules, store, document-language script). :app:lintDebug — 0 errors. :app:assembleDebug succeeds. No added trailing whitespace; line endings preserved.
• Connected, Pixel Fold API 36 emulator:
  • New EpubBookLanguageInstrumentedTest 5/5 — read-aloud offers the book language's voices by default and the override's voices live; read-aloud starts in the override language; a change during read-aloud preparation is applied; the page language follows the override live and is remembered per book; a chapter that declares its own lang/xml:lang takes the override and gets its own value back on Auto (this test fails without the fix below).
  • EpubReaderOptionsOverlayInstrumentedTest 5/10 (the new book-language option test passes; the same 5 fail on main on this emulator). ReadiumEpubOpenInstrumentedTest 16/18 and EpubMediaOverlayControlsInstrumentedTest 3/4 — same failures as on main on this emulator.
• Device: the fork build is used on a Galaxy Z Fold8. This branch itself was run only on the emulator.
• Peer review (Codex GPT-6-Astra) found that Readium 3.0.2's injectLang keeps a chapter's own lang/xml:lang, so the override did not reach hyphenation in such books. Fixed as above; the re-review found no remaining issues.

🤖 Generated with Claude Code

[van-geaux]

Thanks @chortya, the per-book language implementation and tests look good. As this PR is stacked on #302, please rebase it after #302 is merged and resolve the remaining conflicts. Once the branch is updated and CI is green again, it should be ready to merge.

[chortya]

Rebased onto the updated #302 for now, so CI is green. I'll rebase it onto main once #302 is merged.

[van-geaux]

Thanks @chortya, the language picker and live voice switching look really good.

When you rebase, could you also make sure a book’s language choice stays separate between different servers or accounts? I could see the same book ID on another server picking up the old choice.

[chortya]

Thanks, good catch. Rebased onto current main (with #302 and #309) and fixed in 4fc8250:

• The book language choice is now keyed by the active server profile as well as the book, using the same ServerProfileStore.activeId() boundary fix: isolate multiple profiles on the same server #309 uses for downloads and snapshots. The same book ID on another server or account no longer sees it.
• Switching profiles keeps each profile's choices. Before, they were wiped for every profile on each switch.
• Signing out clears only the signed-out profile's choices. This now also covers Kavita and Komga, whose sign-out didn't clear them before.

Tests: EpubBookLanguageTest checks the per-profile keys, and EpubBookLanguageInstrumentedTest.choicesStaySeparateBetweenProfilesAndSignOutClearsOnlyItsOwn checks that two profiles keep separate choices and clearing one leaves the other. All 6 tests in that class pass on a Pixel Fold emulator; CI is green.