chore: sync core lib and CLAUDE.md from agent-core

[avifenesh]

Automated sync of lib/ and CLAUDE.md from agent-core.

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Note

Low Risk
Low risk utility change limited to truncate, but it may slightly alter truncated output for strings containing emoji/surrogate pairs and for maxLength <= 0 inputs.

Overview
Improves truncate in lib/cross-platform/index.js to truncate by Unicode code points instead of UTF-16 code units, preventing broken surrogate pairs (e.g., emoji) in ellipsized text.

Adds a guard to leave strings unchanged when maxLength <= 0, and updates the function’s documentation to reflect the new behavior and length semantics.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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Negative slice index causes output longer than input

High Severity

The truncate function can return strings longer than the original when maxLength is 1 or 2. This happens because maxLength - 3 becomes negative, causing Array.prototype.slice to interpret the end index as an offset from the array's end. The previous String.prototype.substring clamped negative values, avoiding this issue, and the maxLength <= 0 guard doesn't cover these small positive values.

 

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