fix(core): match LF regions of mixed-ending files in edit - #45888
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skyzhao1223 wants to merge 1 commit into
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skyzhao1223 wants to merge 1 commit into
skyzhao1223 wants to merge 1 commit into
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detectLineEnding treated any file containing a single CRLF as a CRLF file and rewrote the model's oldString to CRLF wholesale. The read tool strips trailing \r, so on mixed-ending files the model reproduced pure LF content that the edit path could then never match, failing with a misleading "Could not find oldString". Treat a file as CRLF only when every newline is a CRLF. Consistent CRLF files behave exactly as before; mixed files match as LF, so LF regions become editable and untouched CRLF lines keep their original endings. Editing the CRLF region of a mixed file still requires follow-up work tracked in anomalyco#45880. Fixes anomalyco#45880
This was referenced Aug 28, 2026
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Issue for this PR
Closes #45880
Type of change
What does this PR do?
The read tool strips a trailing
\rfrom each line, so the model always sees pure LF content. ButdetectLineEndingin the edit tool classified any file containing a single CRLF as a CRLF file, and then rewrote the model's entireoldStringto CRLF. On a file with mixed endings (one commit from a Windows colleague is enough), oldStrings targeting LF regions could never match and the edit failed with a misleading "Could not find oldString".This is the conservative first step discussed in the issue: treat a file as CRLF only when every newline is a CRLF. Consistently CRLF files behave exactly as before (covered by the existing "preserves BOM and CRLF line endings" test). Mixed-ending files now match as LF, so their LF regions become editable, and untouched CRLF lines keep their original endings byte-for-byte.
Known limitation left open in #45880: editing the CRLF region of a mixed file still won't match. Fixing that properly needs a policy decision (preserve mixed endings vs. normalize to the dominant ending) plus normalized-search span mapping, so I kept it out of this PR.
How did you verify your code works?
New test: editing the LF region of
alpha\nbeta\r\ngamma\nsucceeds and leaves the CRLF line untouched (ALPHA\r\ngamma\n).bun test ./test/tool-edit.test.ts ./test/tool-write.test.ts: 18 pass.bun run typecheckclean, prettier clean.Screenshots / recordings
Not a UI change.
Checklist