fix: UTF-8 panic on multi-byte string truncation (3 locations) - #482
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Fix three unsafe byte-slice operations that panic when the slice boundary falls inside a multi-byte UTF-8 codepoint: 1. build_commit_prompt() — &diff[..max_chars] in commit_cmd.rs 2. mask_secret() — &s[..4] and &s[s.len()-4..] in secrets_scanner.rs 3. parse_commit_message() — &subject[..69] in commit_cmd.rs All three now use is_char_boundary() to floor the index, matching the existing safe pattern in static_analysis.rs. Added 4 regression tests covering emoji and multi-byte chars at slice boundaries. All 786 tests pass.
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What
Three unsafe byte-slice operations panic when the slice boundary falls inside a multi-byte UTF-8 codepoint (emoji, CJK, Arabic, etc.):
commit_cmd.rs:247—build_commit_prompt()&diff[..max_chars]secrets_scanner.rs:183—mask_secret()&s[..4],&s[s.len()-4..]commit_cmd.rs:349—parse_commit_message()&subject[..69]Why
These are unrecoverable panics on valid UTF-8 input.
cora commitcrashes, and the user cannot proceed. Especially likely in codebases with non-ASCII comments, strings, or variable names.The existing codebase already has the correct pattern in
static_analysis.rs:165-169—is_char_boundary()floor loop. This PR applies the same pattern to all three locations.Testing
commit_prompt_truncates_multibyte_utf8_without_panic— emoji at byte 7998–8002parse_truncates_long_subject_with_multibyte— emoji at byte 67–70 in commit subjectmask_secret_multibyte_no_panic— long secret with emoji prefixmask_secret_multibyte_short_no_panic— short secret with emojicargo clippy --features tree-sitter --bin cora --tests -- -D warningsclean