fix(import): truncate at UTF-8 char boundary to avoid panic on multibyte chars#201
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…yte chars Closes #199. `icm import` panicked when a session contained a multibyte UTF-8 character (e.g. `→`) straddling byte offset 500 (raw_excerpt cap) or 4096 (format-peek cap). Both call sites used a raw byte slice `&s[..N]` which panics if `N` falls inside a char. Reuse the existing `truncate_at_char_boundary` helper at both sites, and add two regression tests that build strings where the multibyte char straddles the cap. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The two existing tests cover `truncate_at_char_boundary` directly. This adds an end-to-end test that runs the actual `cmd_import` flow on a JSONL session whose joined-text byte 500 falls inside `→`, confirming the bug path (raw_excerpt slice) is exercised. Verified against pre-fix code: panics with the exact error message reported in #199. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This was referenced May 10, 2026
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Summary
icm importpanics when a session file contains a multibyte UTF-8 character (→). #199icm importpanicked when a session contained a multibyte UTF-8 character (e.g.→) straddling byte offset 500 (raw_excerptcap) or 4096 (format-peek cap)&s[..N], which panics ifNfalls inside a chartruncate_at_char_boundaryhelper (crates/icm-cli/src/main.rs:2541) — same helper already used for transcript truncation in the hook path→(3 bytes) straddles the cap exactlyReproducer (from #199)
Test plan
cargo test -p icm-cli --bin icm import::— 13 passedcargo test --workspace— 400 passed, 4 ignoredcargo fmt --checkcleancargo clippy --workspace --all-targets -- -D warningsclean🤖 Generated with Claude Code