A client `data-for` passed its loop locals to hydration in memory but never
wrote the `data-wrn-loop-locals` attribute the SSR path writes. Anything that
resolves locals by READING the DOM -- notably a component's `data-wrn-out-*`
output binding, which calls `decodeLoopLocals(componentRoot)` -- therefore
found nothing and silently dropped the call, with no console error.
A plain DOM handler kept working, because it receives locals through the
hydration closure instead, which is what made the failure look arbitrary: the
same loop variable resolved for `@click` and vanished for a component output.
Both loop paths write the marker now, keyed and non-keyed, so the DOM is the
single source of truth. Encoding goes through UTF-8 before base64 as the
server's does; `btoa` on a raw string throws above U+00FF, which would take the
whole loop down for an ordinary non-ASCII label.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
ClintchizandClaude Opus 5
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