[plugin-grid] ObjectGrid's record-detail date fallback renders the MACHINE locale #4541

Found while implementing #4272's residue. Filed rather than fixed: #4272's ruling limited the plugin-grid surface to "ONLY the two date-cell call sites" (the two 'short' consumers in the mobile card view), and this is a third, separate site that was never among them.

The site

packages/plugin-grid/src/ObjectGrid.tsx, inside renderRecordDetail's type-inference fallback:

return (span className="text-sm tabular-nums")[formatDate(value)](/span);

(written without raw angle brackets — the real line is a span wrapping formatDate(value))

formatDate is called with no options, so its default branch hands Intl an undefined tag. undefined is not "the user's locale", it is the machine's — the exact mechanism #4468/#4272 were about. On a zh console this cell renders Aug 15, 2024 while every neighbouring date cell now renders 2024年8月15日.

Why it is a separate site, measured

The #4272 residue comment named the two consumers as ObjectGrid.tsx:2778,2795 at its time of writing. Relocating by content across the intervening churn, both of those are the two calls that pass 'short', and they moved by a constant -121 line offset (2899/2916 at #4531's parent). This site's offset does not fit that mapping, so it was never one of the two.

Scope of the fix

Small and self-contained: the component already reads const displayLocale = useDisplayLocale(); at component level after #4272's PR, so this is one call site gaining { locale: displayLocale }. It needs its own red-first case — a zh session asserting the Chinese form in the record-detail panel, which is a different render path from the mobile card view.

Sibling context: #4272 (the formatter residue, where this was found), #4468 / PR #4512 (the six renderer sites), #4513 (plugin-timeline).

Generated by Claude Code