Fixes two issues with the status_set tool:

1. Emoji Validation Failures

Problem: Emojis with variation selectors (like ✏️) were incorrectly rejected by validation.

Root Cause: The validator used [...str].length to count characters, which counts code points. Emojis with variation selectors (U+FE0F) have 2 code points but represent a single grapheme cluster.

Solution: Use Intl.Segmenter (built-in API) to count grapheme clusters - what users perceive as single characters. This properly handles:

• Variation selectors (✏️, ☀️, ➡️)
• Skin tone modifiers (👋🏻, 👋🏽, 👋🏿)
• Complex emojis (flags, multi-person emojis)

Example:

const segmenter = new Intl.Segmenter("en", { granularity: "grapheme" });
[...segmenter.segment("✏️")].length; // 1 (correct!)
[..."✏️"].length; // 2 (wrong - counts code points)

2. Error Message Styling

Problem: Error messages in StatusSetToolCall used text-sm class, making them smaller than surrounding text in the tool header.

Solution: Removed text-sm class so errors use the same font size as other header content.

Generated with cmux