v0.4.1

[0.4.1] - 2026-06-11

Added

• String-level full-expansion upper/lower case drivers in unicode.casing
  (@stable-since: v0.4.1): upperFull{Len,Buffer,Alloc} /
  lowerFull{Len,Buffer,Alloc} over []const CodePoint and
  upperFullUtf8{Alloc,Writer} / lowerFullUtf8{Alloc,Writer} over UTF-8,
  mirroring the existing foldFull* surface. These apply expanding case
  mappings the simple drivers cannot — "straße" upper-cases to "STRASSE",
  "ff" to "FF". Default root locale (no Turkic tailoring); the lower
  drivers use the context-free mapping (no Greek Final_Sigma — use
  titlecaseUtf8Alloc or the per-scalar API for that).
• Grapheme-cluster-aware display width in unicode.width
  (@stable-since: v0.4.1): stringWidthGraphemes / stringWidthGraphemesLossy
  / stringWidthGraphemesCodePoints and the per-cluster graphemeClusterWidth.
  Unlike the per-scalar stringWidth* estimators (unchanged), these count each
  UAX #29 grapheme cluster once, so a ZWJ emoji family (👨‍👩‍👧) measures 2
  columns instead of 6. Emoji-presentation sequences (VS16) and flags (regional
  indicator pairs) are counted as 2.
• Infallible lossy decode primitives encoding.utf16.decodeU16CodePointLossy
  and encoding.utf32.decodeU32CodePointLossy (@stable-since: v0.4.1),
  mirroring utf8.decodeCodePointLossy: malformed units yield U+FFFD with no
  error union, preconditions asserted. The UTF-16/UTF-32 lossy iterators now
  decode through them, so the "lossy never errors, structurally" guarantee
  (previously UTF-8 only) holds for all three codecs — no catch @panic
  remains on any lossy path.

Changed

• Breaking: the UTF-8 stream's OutputBufferTooSmall error is renamed to
  BufferTooSmall, the name the encoding, transcoding, casing, and collation
  layers already use, so the whole library reports one error for "output
  buffer too small" (UTF8Stream.nextCodePoint / nextCodePointLossy). The
  sibling NeedMoreBytes / EOFReached keep input-side starvation distinct.
• unicode.properties.isAscii now delegates to encoding.isAscii instead of
  hardcoding <= 0x7F; every scalar ASCII check in the library now routes
  through the single encoding.isAscii predicate. The hex-digit predicate docs
  (isHexDigit, isHexDigitWide, isAsciiHexDigit) were clarified so the
  ASCII-vs-Unicode distinction is explicit (no renames).
• Internal: collation-element generation is unified behind one
  Collator.recordAt, shared by buildKey and the incremental comparator, so
  DUCET record lookup, discontiguous-contraction extension, and implicit
  weighting cannot diverge between the sort-key and early-exit paths (closes a
  divergence risk from 0.4.0; no API change).
• Internal: build.zig no longer imports library source (src/utils/root.zig)
  for its some build-option predicate — it carries a local copy, decoupling
  the build graph from module layout.

Removed

• Breaking: the dead BufferIsEmpty error variant is gone from
  UTF8Stream.nextCodePoint / nextCodePointLossy — it was declared but
  returned by no code path (the same cleanup as 0.4.0's error.Undefined).

Fixed

• The unchecked-decode contract ("never panics … undefined in ReleaseFast") is
  now honored uniformly: three internal sites used @panic (which traps in all
  modes) instead of unreachable — most visibly decodeCodePointReverseUnchecked,
  whose doc promised no panic. Replaced with unreachable so behavior matches
  the documented contract.