v0.10.2

Fixes three ui tokens that were theme-blind in dark mode. tokens.bgSubtle, tokens.fgFaint, and tokens.borderStrong reference CSS vars (--color-background-tertiary, --color-text-tertiary, --color-border-secondary) that no host injected, so they always resolved to their hardcoded light fallbacks — rendering white-on-white surfaces, invisible borders, and illegible faint text whenever a host signaled dark. This hit the SDK's own components (Card, ListRow, Prose, Table, Badge, Button, Avatar, SearchField, SegmentedControl, EmptyState, StatusDot) and any app pairing one of these with a theme-aware token. A var() fallback is a static literal that can't branch on theme, so the fix is a theme-aware default layer, not a smarter fallback.

Fixed

• The SDK now ships a neutral default theme (theme-defaults.ts) that backs every color var the token contract references, in both light and dark. It's applied to :root beneath the host's variables — so the host's brand values still win for the keys it provides, and any var the host omits resolves to a theme-correct neutral default. The three previously-unbacked tokens now render correctly in dark mode against any host, a standalone connect() widget, or a third-party host. Values stay neutral (brand arrives only by host injection), preserving the library's host-agnostic design.
• The preview harnesses (vite plugin host + preview server) now inject the three vars in both themes, so synapse dev/preview matches a complete host, and a duplicate --color-text-primary key in those theme maps was removed.

Changed

• Theme variables now reach the DOM through a single shared path, applyThemeVariables(mode, hostVars), replacing three near-duplicate inline injectors in core.ts, connect.ts, and the React <SynapseProvider>. No public API change.