Pin BIZ UDGothic Bold as ghostty CJK fallback#282
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Without an explicit fallback, ghostty's font discovery on macOS 26.5 picks unstable faces for CJK codepoints, and characters like の occasionally render with a different face after display switches (ghostty-org/ghostty#12916). Pinning locks the CJK cascade to a single deterministic face. BIZ UDGothic Bold was chosen because it matches the pre-change appearance ghostty was already producing in most sessions (confirmed via ghostty +show-face and cross-checked by identifying the rendered face through Morisawa Fonts image search, which matched TBUD Gothic — the commercial sibling of BIZ UDGothic). Follow-up in #281: route Bold ASCII to Menlo instead of relying on BIZ UDGothic Bold's Latin glyphs. Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>
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Summary
Pin
BIZ UDGothic Boldas an explicit CJK fallback for ghostty by adding a secondfont-familyline toxdg-config/ghostty/config.Why
Without an explicit CJK fallback, ghostty's runtime font discovery on macOS 26.5 is unstable: CJK codepoints (notably
の) render with different faces after display switches. Root cause is documented upstream in ghostty-org/ghostty#12916 (with related #8712, #707).Pinning locks the CJK cascade to a deterministic face across sessions and display changes.
Why BIZ UDGothic Bold specifically
ghostty +show-face --string="のあ情報"on the unpinned state reportedBIZ UDGothicas the family ghostty was already selecting most of the timeTBUD Gothic Std B(79% for the round sibling, 70% for the base). TBUD Gothic is what BIZ UDGothic is the OFL public release of (Google Fonts specimen)BIZ UDGothic Boldreproduces the pre-change appearance more faithfully than pinning the Regular face (Regular face changes weight/shape enough to be noticeable)Verification
ghostty +show-face --string="のあ情報実際ABCabc0123!@#-_=+()"after the change:の,あ,情,報,実,際) resolve toBIZ UDGothicA-C,a-c,0-3, punctuation) resolve toMonacoConfig took effect on the running ghostty instance without a restart. No visible regression in existing terminal workloads (shell prompts, Claude Code, tmux).
Side effect (follow-up: #281)
Bold ASCII (SGR 1, markdown emphasis) is drawn using
BIZ UDGothic Bold's Latin glyphs, not Monaco. This is because Monaco has no Bold face (system_profiler SPFontsDataTypeconfirmsStyle: Regularonly), so ghostty's per-codepoint fallback picks the first face in the cascade that has both the codepoint and Bold weight, andBIZ UDGothic Boldfits that requirement for ASCII too. This matches the pre-change behavior — ghostty was already routing Bold ASCII through the same font before the pin, so no regression here.