[diffs/edit] Sanitize malformed position components in normalizePosition#986
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Math.min/max pass NaN straight through and fractional indexes break the integer-keyed line-offset lookup, so a NaN (or fractional) line/character resolved to a NaN offset and the degenerate edit range swallowed the entire document — an insert with one malformed component silently erased everything else. normalizePosition now sanitizes before clamping: NaN and -Infinity act as 0, fractions floor, +Infinity clamps to the max. Every position-taking API funnels through it (offsetAt, resolveEdit), so all edit paths are covered. Flips the two malformed-position pins to permanent regression tests with exact expectations; pinned known-bug count drops to 30. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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necolas
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Jul 14, 2026
amadeus
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Jul 14, 2026
amadeus
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lgtm. could there be a valid reason to throw in this situation? or is there something about the API where a user could provide bad data? But probably not a big deal overall
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mm don't think so |
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What
Fixes the worst bug found by the editor-behavior test audit: an edit whose range carries a
NaN(or fractional)line/charactercomponent silently replaced the entire document with the inserted text.Repro before this fix:
Why
normalizePositionclamped with bareMath.max(0, Math.min(...)), which passesNaNstraight through, and fractional indexes survived the clamps only to break the integer-keyed line-offset lookup. Either way the resolved offset becameNaN, and aNaN-ranged edit degenerates into a whole-document replace.Fix
normalizePositionsanitizes components before clamping, consistent with its existing silent-clamp policy for out-of-range values:NaNand-Infinityact as 0, fractions floor,+Infinityclamps to the max. Every position-taking API funnels through it (offsetAt,#resolveEdit), so all edit paths are covered in one place.+Infinitybehavior is byte-identical to before (already clamped correctly by accident).Tests
test.failingpins for this bug flip to permanent regression tests with exact expected outputs (insertion lands at the sanitized position, no content lost).Infinitydivergence pin is unchanged and still passes.test/README.mdknown-bug inventory: 32 → 30.First PR of the failing-test burn-down; next up is the history-equivalence cluster (7 pins).
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