Computer Science and Programming: post #2301 — TG.ME

(Light, Dark, System). The core argument is that users only seek out theme toggles when something is wrong — not to preemptively express intent — making the 'System' state irrelevant at the moment of interaction. Tri-state toggles expose the underlying data model rather than aligning with actual user goals, adding cognitive load and UI friction for an extremely rare use case. A well-implemented two-state toggle can still represent all three underlying states: the first click overrides to the opposite of the current resolved value, and the second click removes the override and returns to system default. Common mistakes include storing a value that matches the system preference (silently pinning the theme) or removing overrides when the OS preference changes. Exceptions where tri-state controls are appropriate include dedicated settings panels and sites that implement meaningfully different color schemes depending on the OS setting.