fix: prevent rich inline CJK fragments from overflowing maxWidth#132
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voidborne-d wants to merge 1 commit intochenglou:mainfrom
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fix: prevent rich inline CJK fragments from overflowing maxWidth#132voidborne-d wants to merge 1 commit intochenglou:mainfrom
voidborne-d wants to merge 1 commit intochenglou:mainfrom
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When CJK text is split across multiple rich inline items (e.g. for styled highlighting), stepPreparedLineGeometry's 'always place at least one content unit' guarantee can push a line past maxWidth. This happens because the line-break engine forces the first segment onto a fresh internal line even when the available width is too small, but the rich inline stepper treats the returned width as fitting without rechecking against the overall line budget. Add an overflow guard in both stepRichInlineLine and its stats-only counterpart: when the line already has content and the new item's fragment (including gap and extra width) would exceed the remaining space, break the line before the item so it starts fresh on the next line with the full width available. Fixes chenglou#120
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Apr 16, 2026
…rapper Remove stepRichInlineLineStats, a ~130-line near-duplicate of stepRichInlineLine. The only difference was whether the optional collectFragment callback fired — passing undefined achieves the same result. PR chenglou#132 demonstrated the drift risk by having to apply the same overflow guard to both functions in parallel. Also inline the single-call-site containsCJKText() wrapper, which was a passthrough to the already-public isCJK(). Similar to the isCJK dedup in PR chenglou#118. Neither change affects behavior. All 84 tests pass.
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Problem
When CJK text is split across multiple rich inline items (e.g. for styled highlighting with different colors), lines can overflow
maxWidth. This is visible in the reproduction at https://codehz.github.io/pretext-bug-diag/ — switching to Chinese + inline rich mode shows text extending past the container boundary.Root Cause
stepPreparedLineGeometryguarantees at least one content unit per line to prevent infinite loops in standalone layout. When the rich inline stepper (stepRichInlineLine) calls it with a smallavailableWidth(the remaining space on a partially-filled line), the line-break engine may return a fragment wider thanavailableWidth— typically one CJK character that doesn't fit. The rich inline stepper then adds this fragment to the current line without rechecking against the overall line budget, causing overflow.The existing "wrap before item" heuristic at this code path only triggers when
gapBefore > 0(collapsed inter-item whitespace), so it misses the case where CJK items abut directly without whitespace.Fix
Add an overflow guard in both
stepRichInlineLineand its stats-only counterpartstepRichInlineLineStats: when the line already has content and the new item's fragment (including gap and extra width) would exceed the remaining space, break the line before the item so it starts fresh on the next line with the full width available.This is placed before the existing "wrap before item" heuristic so it catches all overflow cases regardless of whether there's a gap between items.
Testing
Added two regression tests to the
rich-inline invariantssuite:maxWidthBoth tests verify the fragment collection path (
walkRichInlineLineRanges+materializeRichInlineLineRange) and the stats path (measureRichInlineStats) stay consistent.All 86 existing tests continue to pass.
Fixes #120