Fixed
- Restored vertical Japanese glyph forms with fast shaping enabled. Brackets, long-vowel marks and punctuation now use the correct vertical variants.
Added
- Public-domain EPUB fixtures and a device test guide for comparing the typography fixes.
- Long chapters load without Nickel's fixed 100 ms pauses between local EPUB chunks. Set
ntf_fast_epub_delivery:0to keep those pauses.
Improved
- Lowered the supported firmware floor to 4.21.15015 after compatibility and rendering checks. The smallest optional line spacing still has a page-edge clipping limitation on this firmware.
- Removed the development-only page and page-boundary probes. The fixes and normal diagnostic logging are unchanged.
- The unexpected-thread warning names the caller and clarifies that the fix is skipped for that call.
- Reduced chapter layout work by skipping Qt's repeated preparation of text lines whose glyphs are already ready.
- Reduced page-boundary correction work in long chapters by searching only the line rectangles that can affect each page.