Symptom
Once the theme toggle is used, "follow the system theme" becomes unreachable for the rest of that browser's life. There is no way back.
Mechanism
js/theme-init.js treats three states: dark, light, and key-absent, where absent means follow prefers-color-scheme.
const t = localStorage.getItem('sundial.theme');
if (t === 'dark' || (t === null && matchMedia('(prefers-color-scheme: dark)').matches)) { ... }js/components/dock.js:108 only ever writes two of them, and never removes the key:
localStorage.setItem('sundial.theme', dark ? 'light' : 'dark');So the third state exists, is handled correctly on boot, and is destroyed by the first toggle.
Fix shape
Either cycle the toggle dark → light → system, or clear the key when the chosen value already matches the current system value. theme-init.js needs no change; it already handles the absent key.
Worth deciding which, since the two differ for a user whose system theme changes later in the day: cycling gives an explicit "system" position, clearing is invisible and could be mistaken for the setting not sticking.
Symptom
Once the theme toggle is used, "follow the system theme" becomes unreachable for the rest of that browser's life. There is no way back.
Mechanism
js/theme-init.jstreats three states:dark,light, and key-absent, where absent means followprefers-color-scheme.js/components/dock.js:108only ever writes two of them, and never removes the key:So the third state exists, is handled correctly on boot, and is destroyed by the first toggle.
Fix shape
Either cycle the toggle dark → light → system, or clear the key when the chosen value already matches the current system value.
theme-init.jsneeds no change; it already handles the absent key.Worth deciding which, since the two differ for a user whose system theme changes later in the day: cycling gives an explicit "system" position, clearing is invisible and could be mistaken for the setting not sticking.