An IconButton between the notifications bell and the user menu cycles
the theme mode in radio order (sun/moon/monitor mirror the CURRENT
choice). New useThemeMode() hook is the single write path (persist +
apply + same-document event), so the settings radios and the toggle
stay in sync; AppearanceSection now uses it too. Also rendered for
signed-out visitors — the mode is a device-local preference. i18n de+en;
unit tests for cycle/setter, theme.spec covers cycling, radio sync,
persistence, and the signed-out top bar.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QRtCnB3uLdQtFmvp9HXcRX
theme-contrast.test.ts parses tokens.css and asserts every real UI colour
pairing (4.5:1 text, 3:1 UI) for BOTH palettes, so palette drift fails
unit tests instead of review. theme.test.ts covers resolve/apply logic
(Node >= 22 ships a shadowing undefined localStorage global — the test
brings its own in-memory storage). The a11y pack now runs its four scans
in light AND dark via emulateMedia; the new theme pack exercises the
three-way switch end to end (instant apply, reload persistence, live OS
follow in system mode, override beats OS). ADR 0018 records the theming
model broadly: modes now, accent themes by derivation later.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QRtCnB3uLdQtFmvp9HXcRX
