emoji width bugs mostly come down to how terminals interpret Unicode's "grapheme clusters" vs "codepoints" vs "display cells". emoji isn't one codepoint - it's often multiple joined by zero-width joiners, variation selectors, skin tone modifiers. so the terminal asks wcwidth(), gets 1 or 2, but the actual glyph might render wider or combine into a single shape.
some emoji even change width depending on font. family emoji is like 7 codepoints, shows up as one glyph. most terminals don't track that. they just count codepoints and pray.
unless terminal is using a grapheme-aware renderer and syncs with the font's shaping engine (like freetype or coretext), it'll always guess wrong. wezterm and kitty kinda parse it right often
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