The board
Six buttons that mean nothing to anyone else.
The whole design follows from one decision: the board shows what was logged, and never what it meant.
The design
The legend is the product.
A patient’s screen is a grid of colored buttons. No words, no labels, no counts. The list of what each one means is written once, encrypted, and shown only after a PIN.
That’s why the board opens instantly, with nothing to unlock. A tracker you have to log into is a tracker that doesn’t get used at the moment worth recording — and the board on its own doesn’t say anything. If someone glances over a shoulder mid-tap, what they see is a colored dot and a 7.
Telling them apart
Whatever distinguishes the buttons has to distinguish all six.
Six colors and one shape, or six shapes and one color, or six of each. Any of those works. What doesn’t work is six buttons drawn from four colors, where two of them are near enough the same green that the patient falls back on grid position to remember which was which — at the exact moment they are least able to.
Colored circles are the default, because they’re the version someone actually wants to open. The rest is there for people who need it: roughly one in twelve men has some degree of color vision deficiency, and to them a board encoded in hue alone is six identical circles.
The default palette is chosen on looks alone. It is not color-blind safe and doesn’t try to be — a switch is a better answer than one compromise everybody lives with. The safe set isn’t picked by eye either: it’s fitted against simulated protanopia, deuteranopia and tritanopia and checked for contrast by a script that ships in the repository, because a palette that merely looks considerate to the person who chose it is the failure mode here. Six colors is what makes it work — every pair can be held apart under all three at once, which nine cannot.